US20100190285A1 - Microeletromechanical systems having stored charge and methods for fabricating and using same - Google Patents

Abstract

Many inventions are disclosed. Some aspects are directed to MEMS, and/or methods for use with and/or for fabricating MEMS, that supply, store, and/or trap charge on a mechanical structure disposed in a chamber. Various structures may be disposed in the chamber and employed in supplying, storing and/or trapping charge on the mechanical structure. In some aspects, a breakable link, a thermionic electron source and/or a movable mechanical structure are employed. The breakable link may comprise a fuse. In one embodiment, the movable mechanical structure is driven to resonate. In some aspects, the electrical charge enables a transducer to convert vibrational energy to electrical energy, which may be used to power circuit(s), device(s) and/or other purpose(s). In some aspects, the electrical charge is employed in changing the resonant frequency of a mechanical structure and/or generating an electrostatic force, which may be repulsive.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application is a divisional of, and incorporates herein by reference in its entirety, U.S. patent application Ser. No. 11/446,850, which was filed on Jun. 4, 2006.
BACKGROUND
• This invention relates to electromechanical systems and techniques for fabricating microelectromechanical and/or nanoelectromechanical systems; and more particularly, in one aspect, to fabricating or manufacturing microelectromechanical and/or nanoelectromechanical systems having a mechanical structure encapsulated using thin film or wafer bonding encapsulation techniques and electrical charge supplied to, stored on and/or trapped on one or more portions of the structure.
• Microelectromechanical systems (“MEMS”), for example, gyroscopes, resonators and accelerometers, utilize micromachining techniques (i.e., lithographic and other precision fabrication techniques) to reduce mechanical components to a scale that is generally comparable to microelectronics. MEMS typically include a mechanical structure fabricated from or on, for example, a silicon substrate using micromachining techniques.
• MEMS often operate through the movement of certain elements or electrodes, relative to fixed or stationary electrodes, of the mechanical structures. This movement tends to result in a change in gap distances between moving electrodes and stationary or fixed electrodes (for example, the gap between opposing electrodes). (See, for example, U.S. Pat. Nos. 6,240,782, 6,450,029, 6,500,348, 6,577,040, 6,624,726, and U.S. Patent Applications 2003/0089394, 2003/0160539, and 2003/0173864). For example, the MEMS may be based on the position of a deflectable or moveable electrode of a mechanical structure relative to a stationary electrode.
• The mechanical structures are typically sealed in a chamber. The delicate mechanical structure may be sealed in, for example, a hermetically sealed metal container (for example, a TO-8 “can”, see, for example, U.S. Pat. No. 6,307,815), bonded to a semiconductor or glass-like substrate having a chamber to house, accommodate or cover the mechanical structure (see, for example, U.S. Pat. Nos. 6,146,917; 6,352,935; 6,477,901; and 6,507,082), or encapsulated by a thin film using micromachining techniques during, for example, wafer level packaging of the mechanical structures. (See, for example, International Published Patent Applications Nos. WO 01/77008 A1 and WO 01/77009 A1).
• In the context of the hermetically sealed metal container, the substrate on, or in which the mechanical structure resides may be disposed in and affixed to the metal container. The hermetically sealed metal container also serves as a primary package as well.
• In the context of the semiconductor or glass-like substrate packaging technique, the substrate of the mechanical structure may be bonded to another substrate whereby the bonded substrates form a chamber within which the mechanical structure resides. In this way, the operating environment of the mechanical structure may be controlled and the structure itself protected from, for example, inadvertent contact. The two bonded substrates may or may not be the primary package for the MEMS as well.
• Thin film wafer level packaging employs micromachining techniques to encapsulate the mechanical structure in a chamber using, for example, a conventional oxide (SiO.sub.2) deposited or formed using conventional techniques (i.e., oxidation using low temperature techniques (LTO), tetraethoxysilane (TEOS) or the like). (See, for example, WO 01/77008 A1, FIGS. 2-4). When implementing this technique, the mechanical structure is encapsulated prior to packaging and/or integration with integrated circuitry.
• MEMS have been proposed for a variety of miniaturized systems. For example, miniaturized systems have been proposed to provide distributed sensing capability. In some such systems, miniaturized sensors monitor conditions and transmit signals back to a host receiver. Such systems may prove useful in many applications including for example, automotive tires, homeland security industrial monitoring and weather prediction. However, such systems require electrical power in order to operate.
• Current miniature battery technology provides enough energy to power many of such systems, at least for a period of time. It would be desirable, however, to have the ability to power such systems for a longer period of time without the need to replace the electrical power source.
• In that regard, it has been proposed to power such systems utilizing energy from the environment (sometimes referred to as “energy scavenging” or “energy harvesting”). Some of the most common sources of such energy are vibrational energy, stress (pressure) energy and thermal energy. Of these, vibrational energy may be the most readily available.
• To that effect, methods have been proposed to use MEMS to convert vibrational energy into electrical energy. One such method proposes to use a MEMS having a variable capacitor formed of movable semiconductor plates. Electrical charge is placed on the plates of the variable capacitor. Thereafter, when vibrational energy causes the plates to move apart, the variable capacitor produces electrical energy. The electrical energy can be stored and/or used to power one or more devices and/or systems.
• One roadblock to implementing such a method has been a difficulty encountered in trying to retain the electrical charge on the plates of the capacitor. For example, contaminants within the chamber can result in leakage currents that quickly drain the electrical charge from the plates of the capacitor.
• There is a need for, among other things, a MEMS and/or a technique for fabricating a MEMS that overcomes one, some or all of the shortcomings described above. There is a need for, among other things, a MEMS having a mechanical structure that is encapsulated using thin film encapsulation and/or wafer bonding techniques and that possesses an improved ability to store charge. There is a need for, among other things, a MEMS having a mechanical structure that is encapsulated using wafer level thin film and/or wafer bonding encapsulation techniques, and include one or more structures for use in storing charge within such MEMS.
SUMMARY OF THE INVENTION
• There are many inventions described and illustrated herein.
• The present invention is neither limited to any single aspect nor embodiment, nor to any combinations and/or permutations of such aspects and/or embodiments. Moreover, each of the aspects and/or embodiments of the present invention may be employed alone or in combination with one or more of the other aspects of the present invention and/or embodiments. For the sake of brevity, many of those permutations and combinations will not be discussed separately herein.
• In a first aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a mechanical structure disposed in the chamber, where the method comprises supplying electrical charge to the mechanical structure of the micromechanical structure; and storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day.
• In one embodiment, the micromechanical structure comprises a micromachined mechanical structure. In another embodiment, the mechanical structure comprises a semiconductor material. In another embodiment, the semiconductor material is comprised of polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide. In another embodiment, the encapsulation structure comprises a semiconductor material. In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes electrically isolating the mechanical structure such that at least a portion of the electrical charge will be stored on the mechanical structure for a period of at least one month.
• In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes electrically isolating the mechanical structure such that at least a portion of the electrical charge will be stored on the mechanical structure for a period of at least one year.
• In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes electrically isolating the mechanical structure such that at least a portion of the electrical charge will be stored on the mechanical structure for a period of at least ten years.
• In another embodiment, the mechanical structure includes a first electrode, supplying electrical charge to the mechanical structure includes supplying electrical charge to the first electrode, and storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes storing at least a portion of the electrical charge on the first electrode for a period of at least one day.
• In another embodiment, supplying electrical charge to the mechanical structure includes supplying the mechanical structure with electrical charge from a thermionic electron source.
• In another embodiment, the mechanical structure includes a first electrode disposed in the chamber, the micromechanical structure further includes a second electrode disposed in the chamber, and the method further includes supplying energy to cause relative movement between at least one portion of the first electrode and at least one portion of the second electrode.
• In another embodiment, the first electrode includes a movable mechanical structure and wherein supplying energy to cause relative movement between at least one portion of the first electrode and at least one portion of the second electrode includes supplying energy to cause movement of the movable mechanical structure.
• In another embodiment, the movable mechanical structure includes a spring portion and a mass portion and wherein supplying energy to cause movement of the movable mechanical structure includes supplying energy to cause one or more portions of the movable mechanical structure to resonate at one or more resonant frequencies.
• In another embodiment, supplying energy includes supplying vibrational energy to cause relative movement between the at least one portion of the first electrode and the at least one portion of the second electrode.
• In another embodiment, the first electrode and the second electrode define a first capacitance having a magnitude that depends, at least in part, on a relative positioning of the at least one portion of the first electrode and the at least one portion of the second electrode.
• In another embodiment, the method further includes converting at least a portion of the supplied energy to electrical energy. In another embodiment, the method further includes supplying at least a portion of the electrical energy to at least one circuit or device.
• In another embodiment, the at least one circuit or device includes a circuit having at least one device. In another embodiment, the method further includes supplying at least a portion of the electrical energy to interface circuitry. In another embodiment, the method further includes supplying at least a portion of the electrical energy to interface circuitry configured for wireless communication. In another embodiment, the method further includes supplying at least a portion of the electrical energy to data processing electronics.
• In another embodiment, the method further includes supplying at least a portion of the electrical energy to a sensor that senses a physical quantity and generates an electrical signal indicative thereof.
• In another embodiment, converting at least a portion of the supplied energy to electrical energy includes generating an electrical signal, the method further including supplying the electrical signal to data processing electronics.
• In another embodiment, converting at least a portion of the supplied energy to electrical energy comprises converting at least a portion of the supplied energy to an AC voltage or AC current. In another embodiment, the method further includes using at least a portion of the electrical energy in powering at least one portion of at least one circuit or device. In another embodiment, the at least one circuit or device is disposed in or on the electromechanical device. In another embodiment, the at least one circuit or device is integrated in or on the electromechanical device. In another embodiment, the at least one circuit or device is disposed in or on the substrate. In another embodiment, the method further includes rectifying the AC voltage or AC current to provide a rectified voltage; generating a regulated voltage from the rectified voltage; and powering at least one circuit or device from the regulated voltage.
• In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day comprises storing electrical charge on the mechanical structure for a period of at least one year. In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day comprises storing at least a portion of the electrical charge on the mechanical structure for a period of at least ten years. In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes storing at least 10 percent of the electrical charge on the mechanical structure for a period of at least one day. In another embodiment, storing at least a portion of the electrical charge on the mechanical structure for a period of at least one day includes storing at least 50 percent of the electrical charge on the mechanical structure for a period of at least one day.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a mechanical structure, where the method comprises depositing a sacrificial layer over the mechanical structure; depositing a first encapsulation layer over the sacrificial layer; forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer; removing at least a portion of the sacrificial layer to form the chamber; depositing a second encapsulation layer over or in the vent to seal the chamber; supplying electrical charge to at least one portion of the mechanical structure; and storing at least a portion of the electrical charge on the at least one portion of the mechanical structure for a period of at least one day.
• In one embodiment, storing at least a portion of the electrical charge on the at least one portion of the mechanical structure includes storing at least a portion of the electrical charge on the at least one portion of the mechanical structure after depositing the second encapsulation layer.
• In another embodiment, the first encapsulation layer is comprised of a polycrystalline silicon, amorphous silicon, germanium, silicon/germanium or gallium arsenide.
• In another embodiment, the second encapsulation layer is comprised of polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a first electrode disposed in the chamber, where the method comprises supplying electrical charge to the first electrode of the micromechanical structure; and storing at least a portion of the electrical charge on the first electrode for a period of at least one day.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a first electrode disposed in the chamber, where the method comprises supplying electrical charge to the first electrode of the micromechanical structure; and electrically isolating the first electrode such that at least a portion of the electrical charge is stored on the first electrode for a period of at least one day.
• In another aspect, the present invention includes an electromechanical device where the electromechanical device includes a substrate; an encapsulation structure disposed over at least a portion of the substrate and defining at least a portion of a chamber; and a micromechanical structure that includes a mechanical structure disposed in the chamber, wherein the mechanical structure is supplied with electrical charge and is electrically isolated such that at least a portion of the electrical charge is stored on the mechanical structure for a period of at least one day.
• In one embodiment, the mechanical structure comprises a semiconductor material. In another embodiment, the mechanical structure includes an electrode electrically isolated such that the at least a portion of the electrical charge is stored on the electrode for a period of at least one day. In another embodiment, the mechanical structure comprises a first electrode and the micromechanical structure further includes a second electrode disposed in the chamber and electrically isolated from the first electrode. In another embodiment, the encapsulation structure includes a first encapsulation and a second encapsulation layer. In another embodiment, the first encapsulation layer has at least one vent and the second encapsulation layer is deposited over or in the vent.
• In another embodiment, the electromechanical device further includes a contact, at least one portion of the contact being disposed outside the chamber, and a trench, disposed outside the chamber and around at least a portion of the at least one portion of the contact. In another embodiment, the trench includes a first material disposed therein to electrically isolate the contact.
• In another aspect, the present invention includes an electromechanical device where the electromechanical device includes a substrate; an encapsulation structure disposed over at least a portion of the substrate and defining at least a portion of a chamber; and a micromechanical including an electrode disposed in the chamber, wherein the electrode is supplied with electrical charge and is electrically isolated such that at least a portion of the electrical charge is stored on the electrode for a period of at least one day.
• In another aspect, the present invention includes an electromechanical device, where the electromechanical device includes a substrate, an encapsulation structure disposed over at least a portion of the substrate and defining at least a portion of a chamber, the encapsulation structure including a first encapsulation layer and a second encapsulation layer, the first encapsulation layer including at least one vent through the first encapsulation layer, the second encapsulation being deposited over or in the vent, a micromechanical structure including a mechanical structure disposed in the chamber, wherein the mechanical structure is supplied with electrical charge and is electrically isolated such that at least a portion of the electrical charge is stored on the at least one portion of the mechanical structure for a period of at least one day.
• In another aspect, the present invention includes an electromechanical device, where the electromechanical device includes a substrate, an encapsulation structure disposed over at least a portion of the substrate and defining at least a portion of a chamber, the encapsulation structure including a first encapsulation layer and a second encapsulation layer, the first encapsulation layer including at least one vent through the first encapsulation layer, the second encapsulation being deposited over or in the vent, an electrode disposed in the chamber, wherein the electrode is supplied with electrical charge and is electrically isolated such that at least a portion of the electrical charge is stored on the electrode for a period of at least one day.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a mechanical structure disposed in the chamber, where the method comprises storing electrical charge on the mechanical structure of the micromechanical structure to change a resonant frequency of the mechanical structure.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a first mechanical structure disposed in the chamber and a second mechanical structure disposed in the chamber, where the method comprises storing electrical charge on the first mechanical structure of the micromechanical structure and supplying electrical charge to the second mechanical structure of the micromechanical structure such that the charge on the first mechanical structure and the charge on the second mechanical structure produce an electrostatic repulsive force.
• In one embodiment, the electrostatic repulsive and/or electrostatic attractive force is used in changing the resonant frequency of a mechanical structure.
• In another aspect, the present invention includes a method for use in association with an electromechanical device having a substrate and an encapsulation structure, the encapsulation structure being disposed over at least a portion of the substrate and defining at least a portion of a chamber, the electromechanical device further having a micromechanical structure that includes a mechanical structure disposed in the chamber, where the method comprises providing an electrostatic repulsive force to change a resonant frequency of the mechanical structure.
• In another aspect, an electromechanical device and/or a method for use in association with an electromechanical device employs charge supplying, storing and/or trapping to provide electrostatic repulsive and/or electrostatic attractive force. In another aspect, a system, device circuit and/or method employs one or more of the electromechanical devices and/or one or more of the methods set forth above and/or hereinafter. In another aspect, an electromechanical device and/or a method for use in association with an electromechanical device employs charge supplying, storing and/or trapping to provide electrostatic repulsive and/or electrostatic attractive force.
• Again, there are many inventions described and illustrated herein. This Summary of the Invention is not exhaustive of the scope of the present inventions. Moreover, this Summary of the Invention is not intended to be limiting of the invention and should not be interpreted in that manner. Thus, while certain aspects and embodiments have been described and/or outlined in this Summary of the Invention, it should be understood that the present invention is not limited to such aspects, embodiments, description and/or outline. Indeed, many others aspects and embodiments, which may be different from and/or similar to, the aspects and embodiments presented in this Summary, will be apparent from the description, illustrations and/or claims, which follow.
• In addition, although various features, attributes and advantages have been described in this Summary of the Invention and/or are apparent in light thereof, it should be understood that such features, attributes and advantages are not required, and except where stated otherwise, need not be present in the aspects and/or the embodiments of the present invention.
• Moreover, various objects, features and/or advantages of one or more aspects and/or embodiments of the present invention will become more apparent from the following detailed description and the accompanying drawings. It should be understood however, that any such objects, features, and/or advantages are not required, and except where stated otherwise, need not be present in the aspects and/or embodiments of the present invention.
• It should be understood that the various aspects and embodiments of the present invention that are described in this Summary of the Invention and do not appear in the claims that follow are preserved for presentation in one or more divisional/continuation patent applications. It should also be understood that all aspects and/or embodiments of the present invention that are not described in this Summary of the Invention and do not appear in the claims that follow are also preserved for presentation in one or more divisional/continuation patent applications.
BRIEF DESCRIPTION OF THE DRAWINGS
• In the course of the detailed description to follow, reference will be made to the attached drawings. These drawings show different aspects of the present invention and, where appropriate, reference numerals illustrating like structures, components, materials and/or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, materials and/or elements, other than those specifically shown, are contemplated and are within the scope of the present invention.
• FIG. 1 illustrates a plan view of a portion of a microelectromechanical structure (MEMS);
• FIG. 2A illustrates a plan view of a portion of a micromachined mechanical structure that employs charge supplying, storing and/or trapping and may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIGS. 2B-2D illustrate enlarged plan views of portions of the micromachined mechanical structure ofFIG. 2A, in accordance with certain aspects of the present invention;
• FIG. 3A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 2A) of the portion of the micromachined mechanical structure ofFIG. 2A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 3B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 2A) of the portion of the micromachined mechanical structure ofFIG. 2A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 3C illustrates a cross-sectional view (taken in the direction C-C ofFIG. 2A) of the portion of the micromachined mechanical structure ofFIG. 2A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 3D illustrates a cross-sectional view (taken in the direction D-D ofFIG. 2A) of the portion of the micromachined mechanical structure ofFIG. 2A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 3E illustrates a cross-sectional view (taken in the direction E-E ofFIG. 2A) of the portion of the micromachined mechanical structure ofFIG. 2A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIGS. 4A-4J illustrate cross-sectional views (taken in the direction A-A ofFIG. 2A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIG. 2A, including one embodiment of encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIGS. 5A-5J illustrate further cross-sectional views (taken in the direction B-B ofFIG. 2A) of the fabrication of the portion of micromachined mechanical structure ofFIG. 2A, including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIGS. 6A-6D illustrate plan views of the portion of micromachined mechanical structure ofFIG. 2A, in conjunction with power sources that may be employed therewith, showing various stages that may be employed in storing charge on thefirst electrode19 of the transducer16 (and/or one or more portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), according to certain aspects of the present invention;
• FIGS. 7A-7C illustrate plan views of the portion of micromachined mechanical structure ofFIG. 2A, showing stages that may be employed in the operation of the transducer, according to certain aspects of the present invention;
• FIG. 8A illustrates a graphical representation of the magnitude of the first gap, the magnitude of the second gap, the current into the first electrode, the current into the second electrode, the voltage of the first electrode, the voltage of the second electrode, the voltage across the first capacitance and the voltage across the second capacitance, for one embodiment of the micromachined mechanical structure ofFIG. 2A, under steady state conditions, according to certain aspects of the present invention;
• FIG. 8B illustrates a graphical representation of Vout and Iout for the embodiment of the micromachined mechanical structure illustrated inFIG. 8A, under steady state conditions, according to certain aspects of the present invention;
• FIG. 9A illustrates a cross-sectional view (taken in the direction B-B ofFIG. 2A) of one embodiment of the portion of the micromachined mechanical structure ofFIG. 2A that includes a microstructure that includes a layer of an encapsulation layer deposited thereon, and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 9B illustrates a cross-sectional view (taken in the direction A-A ofFIG. 2A) of the micromachined mechanical structure illustrated inFIG. 2A in conjunction with another embodiment of encapsulation that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 10A illustrates a schematic diagram of the micromachined mechanical structure illustrated inFIG. 2A in conjunction with one or more circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 10B illustrates a schematic diagram of the micromachined mechanical structure illustrated inFIG. 2A in conjunction with one embodiment of the other circuits and/or devices ofFIG. 10A, which includes a charge storing circuit and one or more circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 10C illustrates a schematic diagram of one embodiment of the charge storage circuit illustrated inFIG. 10B, according to aspects of the present invention;
• FIG. 10D illustrates a graphical representation of Vout and Iout for the micromachined mechanical structure illustrated inFIG. 10B, under steady state conditions, according to certain aspects of the present invention;
• FIG. 10E illustrates a schematic diagram of the micromachined mechanical structure illustrated inFIG. 2A in conjunction with one embodiment of the other circuits and/or devices ofFIG. 10A, which includes a power conditioning circuit and one or more other circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 10F illustrates a schematic diagram of one embodiment of the one or more other circuits and/or devices ofFIG. 10E, which includes a transducer, data processing electronics and interface circuitry, which may be coupled to the micromachined mechanical structure illustrated inFIG. 2A, in conjunction with other circuits and/or devices which may be coupled to the interface circuitry, in accordance with certain aspects of the present invention;
• FIG. 10G illustrates a schematic diagram of one embodiment of the DC/DC converter circuit of the power conditioning circuit illustrated inFIG. 10E, according to certain aspects of the present invention;
• FIG. 10H is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction one or more other circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 10I illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 2A (cross sectional view thereof taken in the direction A-A ofFIG. 2A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 10J illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 2A (cross sectional view thereof taken in the direction B-B ofFIG. 2A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 10K is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction with one embodiment of the one or more other circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 10L is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction with one embodiment of the one or more other circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 11 is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction with one embodiment of the one or more other circuits and/or devices that may be coupled thereto, which includes data processing electronics and interface circuitry, in accordance with certain aspects of the present invention;
• FIG. 12A illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 2A (cross sectional view thereof taken in the direction A-A ofFIG. 2A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 12B illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 2A (cross sectional view thereof taken in the direction B-B ofFIG. 2A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 12C is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction with one embodiment of the one or more other circuits and/or devices that may be coupled thereto, which includes data processing electronics, interface circuitry, and one or more external circuits and/or devices that may be coupled to the interface circuitry, in accordance with certain aspects of the present invention;
• FIG. 12D is a block diagram of a microelectromechanical system (MEMS) disposed on a substrate, in conjunction with one embodiment of the one or more other circuits and/or devices that may be coupled thereto, which includes a charge storage circuit, a DC/DC converter, data processing electronics, interface circuitry, and one or more external circuits and/or devices that may be coupled to the interface circuitry, in accordance with certain aspects of the present invention;
• FIG. 12E is a schematic diagram of a distributed system having one or more devices that may employ one or more of the MEMS illustrated inFIG. 1 in conjunction with a communication system and a host receiver and/or processor, in accordance with certain aspects of the present invention;
• FIG. 12F illustrates a schematic diagram of one embodiment of the distributed system ofFIG. 12E to monitor tire conditions, e.g., temperature, pressure and/or vibration, in conjunction with a vehicle having a tire, in accordance with certain aspects of the present invention;
• FIG. 12G illustrates a schematic diagram of one embodiment of the distributed system ofFIG. 12E to monitor an industrial process, in conjunction with a portion of an industrial facility, in accordance with certain aspects of the present invention;
• FIG. 12H illustrates a schematic diagram of another embodiment of the distributed system ofFIG. 12E to monitor one or more environmental conditions (e.g., temperature, pressure, vibration), in conjunction with distributed structures that support the distributed monitoring devices and a structure at a remote location that supports the host receiver and/or processor, in accordance with certain aspects of the present invention;
• FIG. 12I illustrates a schematic diagram of another embodiment of the distributed system ofFIG. 12 to monitor one or more conditions and/or activities relating to security, in conjunction with a structure that support the monitoring devices and a structure at a remote location that supports the host receiver and/or processor, in accordance with certain aspects of the present invention;
• FIG. 12J illustrates a schematic diagram of one embodiment of a device that may be employed in the distributed system ofFIG. 12E, in accordance with certain aspects of the present invention;
• FIGS. 13A-13B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 14A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 14B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 14A, in accordance with certain aspects of the present invention;
• FIG. 15A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 14A) of the portion of the micromachined mechanical structure ofFIG. 14A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 15B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 14A) of the portion of the micromachined mechanical structure ofFIG. 14A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 16 illustrates a plan view of the portion of micromachined mechanical structure illustrated inFIGS. 14A-14B andFIGS. 15A-15B, in conjunction with power sources that may be employed therewith, showing one embodiment for employing the thermionic electron source ofFIGS. 14A-14B andFIGS. 15A-15B to facilitate supplying, storing and/or trapping of electrical charge, in accordance with certain aspects of the present invention;
• FIGS. 17A-17J illustrate cross-sectional views (taken in the direction A-A ofFIG. 14A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 14A-14B andFIGS. 15A-15B including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 18A illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 14A (cross sectional view thereof taken in the direction A-A ofFIG. 14A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 18B illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 14A (cross sectional view thereof taken in the direction B-B ofFIG. 14A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIGS. 19A-19B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 20A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 20B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 20A, in accordance with certain aspects of the present invention;
• FIG. 21A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 20A) of the portion of the micromachined mechanical structure ofFIG. 20A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 21B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 20A) of the portion of the micromachined mechanical structure ofFIG. 20A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 21C illustrates a cross-sectional view (taken in the direction C-C ofFIG. 20A) of the portion of the micromachined mechanical structure ofFIG. 20A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 22 illustrates a plan view of the portion of micromachined mechanical structure illustrated inFIGS. 20A-20B andFIGS. 21A-21C, in conjunction with a power source that may be employed therewith, showing one embodiment for employing the electron gun ofFIGS. 20A-20B andFIGS. 21A-21C to facilitate supplying, storing and/or trapping of electrical charge, in accordance with certain aspects of the present invention;
• FIGS. 23A-23J illustrate cross-sectional views (taken in the direction A-A ofFIG. 20A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 20A-20B andFIGS. 21A-21C including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 24A illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 20A (cross sectional view thereof taken in the direction A-A ofFIG. 20A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 24B illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 20A (cross sectional view thereof taken in the direction B-B ofFIG. 20A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIGS. 25A-25B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 26A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 26B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 26A, in accordance with certain aspects of the present invention;
• FIG. 27A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 26A) of the portion of the micromachined mechanical structure ofFIG. 26A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 27B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 26A) of the portion of the micromachined mechanical structure ofFIG. 26A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 27C illustrates a cross-sectional view (taken in the direction C-C ofFIG. 26A) of the portion of the micromachined mechanical structure ofFIG. 26A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIGS. 28A-28E illustrate a plan view of the portion of micromachined mechanical structure illustrated inFIGS. 26A-26B andFIGS. 27A-27C, in conjunction with a power source that may be employed therewith, showing one embodiment for employing the mechanical structures ofFIGS. 26A-26B andFIGS. 27A-27C to facilitate supplying, storing and/or trapping of electrical charge, in accordance with certain aspects of the present invention;
• FIGS. 28F-28I illustrate a plan view of the portion of micromachined mechanical structure illustrated inFIGS. 26A-26B andFIGS. 27A-27C, in conjunction with a power source that may be employed therewith, showing another embodiment for employing the mechanical structures ofFIGS. 26A-26B andFIGS. 27A-27C to facilitate supplying, storing and/or trapping of electrical charge, in accordance with certain aspects of the present invention;
• FIGS. 29A-29J illustrate cross-sectional views (taken in the direction A-A ofFIG. 26A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 26A-26B andFIGS. 27A-27C, including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 30A illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 26A (cross sectional view thereof taken in the direction A-A ofFIG. 26A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 30B illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 26A (cross sectional view thereof taken in the direction B-B ofFIG. 26A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIGS. 31A-31B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 32A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 32B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 32A, in accordance with certain aspects of the present invention;
• FIG. 33A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 32A) of the portion of the micromachined mechanical structure ofFIG. 32A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 33B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 32A) of the portion of the micromachined mechanical structure ofFIG. 32A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIGS. 34A-34D illustrate a plan view of the portion of micromachined mechanical structure illustrated inFIGS. 32A-32B andFIGS. 33A-33C, in conjunction with a power source that may be employed therewith, showing one embodiment for employing the mechanical structures ofFIGS. 32A-32B andFIGS. 33A-33B to facilitate supplying, storing and/or trapping of electrical charge, in accordance with certain aspects of the present invention;
• FIGS. 35A-35J illustrate cross-sectional views (taken in the direction A-A ofFIG. 32A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 32A-32B andFIGS. 33A-33B, including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 36A illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 32A (cross sectional view thereof taken in the direction A-A ofFIG. 32A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 36B illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 36A (cross sectional view thereof taken in the direction B-B ofFIG. 32A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIGS. 37A-37B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 38A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 38B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 38A, in accordance with certain aspects of the present invention;
• FIG. 38C illustrates a cross-sectional view (taken in the direction A-A ofFIG. 38A) of the portion of the micromachined mechanical structure ofFIG. 38A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIGS. 39A-39C illustrate plan views of the portion of micromachined mechanical structure ofFIG. 38A, showing stages that may be employed in the operation of the transducer of the micromachined mechanical structure ofFIGS. 38A-38C, according to certain aspects of the present invention;
• FIGS. 40A-40J illustrate cross-sectional views (taken in the direction A-A ofFIG. 38A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 38A-38C, including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 41 illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 38A (cross sectional view thereof taken in the direction A-A ofFIG. 38A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIG. 42 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 43 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 44 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 45 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 46A illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 46B illustrates an enlarged plan view of a portion of the micromachined mechanical structure ofFIG. 46A, in accordance with certain aspects of the present invention;
• FIG. 47A illustrates a cross-sectional view (taken in the direction A-A ofFIG. 46A) of the portion of the micromachined mechanical structure ofFIG. 46A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIG. 47B illustrates a cross-sectional view (taken in the direction B-B ofFIG. 46A) of the portion of the micromachined mechanical structure ofFIG. 46A and one embodiment of an encapsulation structure that may be employed therewith, in accordance with certain aspects of the present invention;
• FIGS. 48A-48B illustrate plan views of the portion of micromachined mechanical structure ofFIG. 46A, showing stages that may be employed in the operation of the micromachined mechanical structure ofFIGS. 46A-46B andFIGS. 47A-47B, according to certain aspects of the present invention;
• FIGS. 49A-49J illustrate cross-sectional views (taken in the direction A-A ofFIG. 46A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 46A-46B andFIGS. 47A-47B including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIGS. 50A-50J illustrate cross-sectional views (taken in the direction B-B ofFIG. 46A) of one embodiment of the fabrication of the portion of the micromachined mechanical structure ofFIGS. 46A-46B andFIGS. 47A-47B including one embodiment of an encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention;
• FIG. 51 illustrates a cross-sectional view of a MEMS according to certain aspects of the present inventions, including the portion of the micromachined mechanical illustrated inFIG. 46A (cross sectional view thereof taken in the direction A-A ofFIG. 46A) and an integrated circuit portion, both portions of which are disposed or integrated on or in a common substrate;
• FIGS. 52A-52B illustrate cross-sectional views of micromechanical structures, which may be monolithically integrated on or within the substrate of a MEMS, in accordance with certain aspects of the present invention;
• FIG. 53 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 54 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 55 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIG. 56 illustrates a plan view of a portion of another micromachined mechanical structure that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention;
• FIGS. 57A-57F illustrate schematic diagrams of various embodiments of a microphone that includes a transducer, e.g., the transducer of the micromachined mechanical structure illustrated inFIGS. 36A-36B andFIGS. 37A-37B, in conjunction with one or more external circuits and/or devices that may be coupled thereto, in accordance with certain aspects of the present invention;
• FIG. 58A illustrate plan view of a resonator that may have electrical charge stored on and/or trapped on one or more portions thereof, according to certain aspects of the present invention;
• FIG. 58B illustrates a flowchart showing stages that may be employed in supplying, storing and/or trapping electric charge on one or more portions of a resonator, to change the resonant frequency of the resonator, according to certain aspects of the present invention;
• FIG. 59 illustrates a block diagram of one embodiment of electrostatic repulsion, in accordance with certain aspects of the present invention;
• FIGS. 60A-60B illustrate plan views of a portion of micromachined mechanical structure ofFIGS. 2A-2D,3A-3E,6A-6D,7A-7C,8A-8B,9A-9B,13A-13B,FIGS. 14A-14B,15A-15B,16,18A-18B,19A-19B,20A-20B,21A-21C,22,24A-24B,25A-25B,FIGS. 26A-26B,27A-27C,28A-28I,30A-30B,31A-31B,32A-32B,33A-33B,34A-34D,36A-36B and37A-37B, showing stages that may be employed in providing electrostatic repulsion and/or electrostatic attraction, according to certain aspects of the present invention;
• FIG. 61 illustrates a plan view of a portion of micromachined mechanical structure ofFIGS. 38A-38C,39A-39C,40A-40J,41 and42-45, showing stages that may be employed in providing electrostatic repulsion and/or electrostatic attraction, according to certain aspects of the present invention;
• FIG. 62 illustrates a plan view of a portion of micromachined mechanical structure ofFIGS. 46A-46B,47A-47B,48A-48B,49A-49J,50A-50J,51,52A-52B and53-56, showing stages that may be employed in providing electrostatic repulsion and/or electrostatic attraction, according to certain aspects of the present invention; and
• FIG. 63 illustrates a flowchart of stages in a process for employing an electrostatic repulsive force and/or an electrostatic attractive force to increase and/or decrease the resonant frequency of a movable structure, according to certain aspects of the present invention.
DETAILED DESCRIPTION
• There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a thin film or wafer encapsulated MEMS, and a technique of fabricating or manufacturing a thin film or wafer encapsulated MEMS that supplies, stores and/or traps electrical charge on one or more (i.e., one, some or all) portions of the MEMS. In some embodiments, after encapsulation of MEMS, electrical charge is supplied to, stored on and/or trapped on, a portion of a micromachined mechanical structure disposed in a chamber. In some embodiments, the micromachined mechanical structure includes a capacitive transducer and the electrical charge is supplied to, stored on and/or trapped on a portion thereof, thereby enabling the capacitive transducer to convert vibrational energy to electrical energy. The electrical energy may be used to power one or more circuits and/or devices and/or for other purpose(s).
• Some embodiments have the ability to store at least a portion of the electrical charge for at least ten years. In one such embodiment, a capacitive transducer on which the electrical charge is supplied, stored and/or trapped, will have the ability to generate electrical energy for at least ten years. To that effect, the environment and the surfaces within the chamber are sufficiently free of contaminants to prevent leakage currents that would otherwise lead to excessive drain of the electrical charge stored on and/or trapped on the portion of the micromachined mechanical structure. Notably, structures outside the chamber may have more contamination and/or greater potential for leakage current and/or drain than structures inside the chamber. Thus, some embodiments have the ability to provide electrical isolation to conductive structures inside and/or outside the chamber.
• Some embodiments may not need to store a portion of the electrical charge for at least ten years. For example, in some applications, it is sufficient to store a portion of the electrical charge for at one year, one month, or one day. Thus, some embodiments have the ability store at least a portion of the electrical charge for at least one year, at least one month and/or at least one day. Notably, some of such embodiments may be able to operate with more contamination, less electrical isolation, more leakage and/or more drain of electrical charge than embodiments that that require the ability to store a portion of the electrical charge for at least ten years.
• In some embodiments, one or more methods and/or structures may be employed to supply, store and/or trap the electrical charge a portion of a micromachined mechanical structure. In one embodiment, a breakable link is employed to supply and trap the electrical charge. In one such embodiment, the breakable link comprises a fuse. In another embodiment, a thermionic electron source is employed to supply and trap the electrical charge. In another embodiment, a movable mechanical structure is employed to supply and trap the electrical charge. In one such embodiment, the movable structure comprises a resonator, e.g., a resonant mode cantilever.
• In some embodiments, electrical charge is supplied, stored and/or trapped on a mechanical structure to change the resonant frequency of the mechanical structure. In some embodiments, stored electrical charge is employed in generating an electrostatic force. In some embodiments, the electrostatic force comprises a repulsive force. In some embodiments, the electrostatic force is employed to change the resonant frequency of a mechanical structure.
• With reference toFIG. 1, in one exemplary embodiment, aMEMS10 includes a micromachinedmechanical structure12 disposed onsubstrate14, for example, an undoped semiconductor-like material, a glass-like material, or an insulator-like material.
• The micromachinedmechanical structure12 may be any type of micromachined mechanical structure including, for example, but not limited to an energy harvesting device (e.g., a vibrational energy to electrical energy converter), an accelerometer, a gyroscope or other type of transducer (for example, microphone, vibration sensor, pressure sensor, strain sensor, tactile sensor, magnetic sensor and/or temperature sensor), a resonator, a resonant filter, and/or any combination thereof.
• In some embodiments, micromachinedmechanical structure12 is a micromachined mechanical structure that includes a capacitive transducer, which may be any type of capacitive transducer, for example, an energy harvesting device (e.g., a vibrational energy to electrical energy converter), a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof.
• The micromachinedmechanical structure12 may also include mechanical structures of a plurality of energy harvesting devices (e.g., vibrational energy to electrical energy converters), transducers and/or sensors (including, for example, one or more accelerometers, gyroscopes, vibration sensors, pressure sensors, microphones, tactile sensors and/or temperature sensors), resonators, resonant filters and/or any combination thereof. Where the micromachinedmechanical structure12 is an accelerometer, the micromachined mechanical structure may include comb-like finger electrode arrays that comprise the sensing features of the accelerometer (see, for example, U.S. Pat. No. 6,122,964).
• FIGS. 2A-2D andFIGS. 3A-3E illustrate plan views and cross sectional views, respectively, of a portion of one embodiment of micromachinedmechanical structure12 employed in the MEMS ofFIG. 1. This embodiment of micromachinedmechanical structure12 includes atransducer16, one or more portions of which may have electrical charge supplied thereto, stored on and/or trapped thereon, in accordance with certain aspects of the present invention. Thetransducer16 may be any type of transducer, for example, an energy harvesting device (e.g., a vibrational energy to electrical energy converter), a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however, thetransducer16 is not limited to such.
• In this embodiment,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example, afirst electrode19, asecond electrode20 and athird electrode22.
• The first, second andthird electrodes19,20,22, and/or other mechanical structure(s) oftransducer16 may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table, for example silicon, germanium, carbon; also combinations of these, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• Theelectrodes19,20,22, and/or other mechanical structure(s) oftransducer16 may have any configuration (e.g., size, shape, orientation). In the illustrated embodiment, for example,first electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. The movablemechanical structure28 includes aspring portion30 and amass portion32. Thespring portion30 is disposed between the second andthird electrodes20,22. The second andthird electrodes20,22 define fixed mechanical structures having generally rectangular shapes disposed on opposite sides of thespring portion30 and areference plane33.
• With reference toFIG. 2B, the movablemechanical structure28 may include first andsecond surfaces40,42.First surface40 may face in a direction toward afirst surface44 of thesecond electrode20 and may be spaced therefrom by afirst gap46.Second surface42 may face in a direction toward afirst surface48 of thethird electrode22 and may be spaced therefrom by asecond gap50.
• Thespring portion30 may be elongated and may include first and second ends56,58. Thefirst end56 may connect to themass portion32. Thesecond end58 may connect to the fixedmechanical structure26. Themass portion32 may have a generally rectangular configuration and/or alength66 and awidth68. Thespring portion30 may have alength62 and awidth64. In some embodiments, thelength66 of themass portion32, thewidth68 of themass portion32 and thelength62 of thespring portion30 are each at least five times as large as thewidth64 of thespring portion30. In one embodiment, thespring portion30 has alength62 and awidth64 of about 300 microns and about 5 to 10 microns, respectively, and themass portion32 has alength66 and awidth68 of at least about 540 microns and at least about 300 microns, respectively. In one embodiment, the structures have a thickness in a range of at least about 20 microns to about 150 microns.
• With reference toFIG. 2C, themass portion32 may include a plurality ofopenings70 to facilitate etching and/or removal of sacrificial material from beneath themass portion32 during fabrication of the micromachinedmechanical structure12, as further described hereinafter. The plurality ofopenings70 may have any configuration (e.g., shape, arrangement). For example,openings70 may be rectangular (or generally rectangular) and similar to one another, as shown, but are not limited to such. In some embodiments, each opening70 has a generally square shape that measures approximately 1 micron on a side, and is spaced apart from one another by adistance72 of approximately 10 microns.
• One or more clearances, e.g.,clearances76a,76b(FIG. 3A), may be provided between the movablemechanical structure28 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g.,clearances76a,76b, may reduce the possibility of friction and/or interference between the movablemechanical structure28 and the one or more other portions of the micromachinedmechanical structure12. In some embodiments, the one or more clearances, e.g.,76a,76b, provide clearance around each surface of the movablemechanical structure28 except atend58 where the movablemechanical structure28 connects to the fixedmechanical structure26, such that the movable structure is suspended from the fixedmechanical structure26.
• The first andsecond electrodes19,20 collectively define a first capacitance. The first andthird electrodes19,22 collectively define a second capacitance. The magnitude of the first capacitance depends (at least in part) on the configurations of the first andsecond electrodes19,20 and on the relative positioning of the first andsecond electrodes19,20. The magnitude of the second capacitance depends (at least in part) on the configurations of the first andthird electrodes19,20 and relative positioning of the first andthird electrodes19,22.
• In some embodiments, the first capacitance and second capacitance each have a value in a range of from about one femptofarad to about one nanofarad (i.e., with the movable mechanical structure of the first electrode centered between the second electrode and the third electrode), more preferably a first capacitance and a second capacitance each having a value equal to about one picofarad (i.e., with the movable mechanical structure of the first electrode centered between the second electrode and the third electrode). In some embodiments, large values of capacitances may require more area and/or volume than small values of capacitance.
• As further described hereinafter, exposing the micromachinedmechanical structure12 to an excitation (e.g., vibration) having a lateral component causes the movablemechanical structure28 of thefirst electrode19 to move in a lateral direction and that causes a change in the magnitude of the first capacitance and the magnitude of the second capacitance. In the absence of an excitation thespring portion30 may be stationary and disposed at a position that is centered about the reference plane33 (i.e., equidistant or at least approximately equidistant between the first andsecond electrodes20,22). With such positioning of the movablemechanical structure28, the first capacitance and the second capacitance may be approximately equal to one another.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying and/or trapping electrical charge on thefirst electrode19 of the transducer16 (and/or any other portion(s) of micromachinedmechanical structure12 on which charge is to be stored).
• Unless specified otherwise, the phrase “trap electrical charge” means to provide electrical isolation such that at least a portion of the electrical charge is stored for at least some period of time. Similarly, the phrase “trapping electrical charge” means providing electrical isolation such that at least a portion of the electrical charge is retained for at least some period of time.
• In addition, unless specified otherwise, the term “store” includes but is not limited to store, retain, keep and/or leave. The phrase “store on” includes, but is not limited to, store on, store in, retain on, retain in, keep on, keep in, leave on, and/or leave in. Similarly, unless specified otherwise, the term “storing” and other forms (i.e., store, stored) includes but is limited to storing, retaining, keeping and/or leaving. The phrase “storing on” and other forms (i.e., store on, stored on) includes, but is not limited to, storing on, storing in, retaining on, retaining in, keeping on, keeping in, leaving on, and/or leaving in. Storing may be carried out using any method(s) and/or structure(s) including, for example, but not limited to by trapping.
• In this embodiment, the one or moremechanical structures82 include afirst electrode84, asecond electrode86 and abreakable link88. The one or moremechanical structures82 may be comprised of, any suitable material for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table, for example silicon, germanium, carbon; also combinations of these, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• The one or moremechanical structures82 may have any configurations (e.g., size, shape, orientation). In the illustrated embodiment, for example, the first andsecond electrodes84,86 include fixed mechanical structures having generally rectangular shapes spaced apart from one another by one or more one or more gaps, e.g., agap87. Thebreakable link88 includes afuse89.
• With reference toFIG. 2D, thefuse89 may include first andsecond portions90,91. Thefirst portion90 may have afirst end90aconnected to thefirst electrode84 and asecond end90bconnected to thesecond electrode86. Thesecond portion91 may have afirst end91aconnected to thefirst portion90 of thefuse89 and asecond end91bconnected to thefirst electrode19 of thetransducer16.
• As further described hereinafter, thefuse89 has two states. In a first state, thefuse89 defines an electrically conductive path that connects at least one of the one or moremechanical structures82, e.g.,electrodes84,86, to thefirst electrode19 of transducer16 (and/or any other portion(s) of micromachinedmechanical structure12 on which charge is to be stored). In the second state, one or more portions of thefuse89 is “blown” (e.g., melted and/or ruptured) to break the connection between the at least one of the one or more ofmechanical structures82, e.g.,electrodes84,86, and thefirst electrode19 of transducer16 (and/or any other portion(s) of micromachinedmechanical structure12 on which charge is to be stored).
• To this effect, one or more portions of thefuse89 may have a configuration adapted to increase the thermal resistance of such portions, which may reduce the amount of energy needed to heat one or more portions of the fuse to a temperature that causes one or more of such portions to “blow”. In this embodiment, for example, fuse89 includes aportion92 that defines a conductive path having a meandering shape. The meandering shape may be regular (e.g., serpentine, as shown) or irregular. In some embodiments, such portion(s) define a major portion (e.g., more than half) of the conductive path of thefuse89.
• One or more clearances, e.g.,clearances93a(FIG. 3A),93b(FIG. 3A),93c(FIG. 2B), may be provided between one or more portions of thefuse89 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g., clearances93a-93c, may help reduce the thermal conductivity between the fuse and the rest of the micromachinedmechanical structure12, which may in turn reduce the amount of energy needed to heat one or more portions of thefuse89 to a temperature that causes thefuse89 to “blow”. In some embodiments, the one or more clearances, e.g., clearances93a-93c, define a clearance around each surface of thefuse89 except at ends90a,90b,91bwhere thefuse89 connects to the first andsecond electrode86,88 of the one or moremechanical structures82 and thefirst electrode19 of thetransducer16, respectively, such that thefuse89 is suspended from the first andsecond electrodes84,86 of the one or moremechanical structures82 and thefirst electrode19 of thetransducer16.
• One or more ofelectrodes20,22,84,86, may include contact areas, e.g.,contact areas84a,86a,20a,22a, respectively, which may provide electrical paths betweenelectrodes20,22,84,86, and one or more other circuits and/or devices, e.g., one or more other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E,10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D), interface circuitry388 (FIG. 11 andFIGS. 12A-12D), and/or power sources, e.g.,voltage sources300,304 (FIGS. 6A-6C).
• The micromachinedmechanical structure12 may further define one or more field areas, e.g.,field areas94,95,96, disposed on, above, or insubstrate14. In some embodiments, one or more of the field areas (1) provide mechanical support for one or more portions of theMEMS10 and/or (2) define one or more substrate areas for fabrication of electronic or electrical components or integrated circuits (for example, transistors, resistors, capacitors, inductors and other passive or active elements). The one or more field areas may comprise any material or materials, for example, monocrystalline silicon, polycrystalline silicon and/or a combination thereof. One or more clearances, e.g.,clearance97, may be provided between one or more of the field areas and/or one or more other structures within the micromachinedmechanical structure12. Such clearances, e.g.,clearance97, may have any size, for example, about 1 micron.
• Referring toFIGS. 3A-3E, the micromachinedmechanical structure12 may further define one or more insulation areas, e.g.,insulation areas109,110,112,114,116, to anchor the one or more mechanical structures, e.g.,electrodes19,20,22,84,86, respectively, to thesubstrate14, while providing electrical isolation between the substrate and such mechanical structures, e.g.,electrodes19,20,22,84,86, respectively. In this embodiment,insulation area109 is disposed between thesubstrate14 and the fixedmechanical structure26 ofelectrode19 to anchor thefirst electrode19 to thesubstrate14 while providing electrical isolation between thesubstrate14 and theelectrode19.Insulation area110 is disposed between the substrate andelectrode20 to anchorelectrode20 to thesubstrate14 while providing electrical isolation between thesubstrate14 andelectrode20.Insulation area112 is disposed between thesubstrate14 andelectrode22 to anchorelectrode22 to the substrate while providing electrical isolation between thesubstrate14 andelectrode22.Insulation area114 is disposed between thesubstrate14 andelectrode84 to anchorelectrode84 to thesubstrate14 while providing electrical isolation between thesubstrate14 andelectrode84.Insulation area116 is disposed between the substrate andelectrode86 to anchorelectrode86 to thesubstrate14 while providing electrical isolation between thesubstrate14 andelectrode86. The one or more insulation areas, e.g.,insulation areas109,110,112,114,116, may comprise, for example, silicon dioxide or silicon nitride.
• The micromachinedmechanical structure12 may further define one or more insulation areas, e.g.,insulation areas130,132,134,136, disposed superjacent one or more of the mechanical structures, e.g.,electrodes20,22,84,86, to partially, substantially or entirely surroundcontact areas20a,22a84a,86a, ofelectrodes20,22,84,86, respectively, as may be desired. One or more of such insulation areas, e.g.,insulation areas130,132,134,136, may define one or more openings, e.g.,openings140,142,144,146, to facilitate electrical contact to the mechanical structures, e.g.,electrodes20,22,84,86, respectively. In this embodiment, for example,insulation area130 is disposedsuperjacent electrode20 and defines opening140 to facilitate contact toelectrode20.Insulation area132 is disposedsuperjacent electrode22 and defines opening142 to facilitate contact toelectrode22.Insulation area134 is disposedsuperjacent electrode84 and defines opening144 to facilitate contact toelectrode84, as may be desired.Insulation area136 is disposedsuperjacent electrode86 and defines opening146 to facilitate contact toelectrode86. The one or more insulation areas, e.g.,insulation areas130,132,134,136, may comprise, for example, silicon dioxide or silicon nitride.
• Surfaces of the one or more insulation areas, e.g.,insulation areas109,110,112,114,116 andinsulation areas130,132,134,136, are sufficiently free of contaminants that would otherwise result in excessive reduction in electrical isolation, excessive leakage current and/or excessive drain of the electrical charge to be supplied to, stored on and/or trapped on thefirst electrode19 of the transducer16 (and/or any other portion(s) of micromachinedmechanical structure12 on which charge is desired to be stored), relative to any requirements, in such embodiments, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge.
• Notably, some embodiments may be able to operate with more contamination, less electrical isolation, more leakage and/or more drain of electrical charge than other embodiments. For example, some embodiments that store a portion of the electrical charge for one day may be able to tolerate more contamination, less electrical isolation, more leakage and/or more drain of electrical charge than embodiments that require the ability to store at least a portion of the charge for a period of at least ten years.
• Thus, as used herein, the term “sufficiently free” means “sufficiently free” relative to any requirements, in any given embodiment, that relate, directly and/or indirectly, to contamination. For example, a surface and/or atmosphere that is not “sufficiently contaminant free” for one embodiment may nonetheless be “sufficiently contaminant free” for another embodiment. Similarly, the term “excessive” means “excessive” relative to any requirements, in any given embodiment, that relate, directly and/or indirectly, to electrical isolation, leakage current and/or drain. For example, an “excessive reduction in electrical isolation” in one embodiment may not be an “excessive reduction in electrical isolation” in another embodiment. An “excessive leakage current” in one embodiment may not be an “excessive leakage current” in another embodiment.
• Unless specified otherwise, the terms “electrically isolating” (and other forms, e.g., “electrically isolate”, electrically isolated”) mean separating (separate, separated, respectively) from electrically conductive structures by means of one or more electrical insulators. An electrically conductive structure may be an electrically conductive structure and/or an electrically conductive portion of a structure. An electrical insulator may be an electrical insulator and/or an electrical insulator portion of a structure. An electrical insulator may or may not be an ideal or near ideal electrical insulator. Rather, an electrical insulator may be any type of electrical insulator (e.g., quality, composition, form, e.g., solid, liquid, gas, vacuum) and may have any configuration (e.g., shape, size) so long as any requirements, relating to insulation resistance, which can vary from embodiment to embodiment, are met.
• Electrically isolating results in electrical isolation. The electrical isolation provided in any given embodiment depends, at least in part, on the characteristics of the one or more electrical insulators that provide the electrical isolation as well as the characteristics of any contaminants in, on and/or around such electrical insulators. Thus, some embodiments may require and/or provide different electrical isolation than other embodiments. For example, some embodiments may employ different electrical insulator(s) and/or may have different amounts of contamination than the electrical insulator(s) and contamination in other embodiments. In some embodiments, electrical isolation may be characterized in terms of an electrical resistance provided thereby.
• In some embodiments, the electrical isolation desired between the first electrode19 (and/or one or more other portions of the micromachined mechanical structure on which electrical charge is desired to be stored) and the substrate14 (and/or other portions of micromachined mechanical structure, e.g., e.g.,electrodes19,20,22,84,86) is at least ten teraohms. Electrical isolation of at least this magnitude helps make it possible to store at least a portion of the electrical charge on the one or more portions of the micromachined mechanical structure for at least one day. However some embodiments employ an electrical isolation much greater than ten teraohms, for example, to help make it possible to store at least a portion of the electrical charge for periods of time greater than one day and/or to help make it possible to store a greater portion of the electrical charge. Some embodiments employ an electrical isolation greater than 10.sup.17 ohms, preferably greater than 10.sup.18 ohms. In some embodiments, the electrical isolation is greater than 10.sup.19 ohms, more preferably greater than 10.sup.20 ohms. Some other embodiments, however, may employ electrical isolation less than ten teraohms.
• The micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. In some embodiments, the atmosphere contained in thechamber150 may provide mechanical damping for the mechanical structures of one or more micromachined mechanical structures (for example, an accelerometer, a pressure sensor, a tactile sensor and/or temperature sensor).
• In this embodiment,atmosphere152 is sufficiently free of contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface contamination and/or surface leakage and thereby lead to excessive drain of the electrical charge to be supplied to, stored on and/or trapped on thefirst electrode19 of the transducer16 (and/or any other portion(s) of micromachinedmechanical structure12 on which charge is desired to be stored), relative to any requirements, in such embodiments, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge.
• As stated above, some embodiments may be able to tolerate more contamination, less electrical isolation, more leakage and/or more drain of electrical charge than other embodiments. In that regard, as stated above, the term “sufficiently free” means “sufficiently free” relative to any requirements, in any given embodiment, that relate, directly and/or indirectly, to contamination. For example, a surface and/or atmosphere that is not “sufficiently contaminant free” for one embodiment may nonetheless be “sufficiently contaminant free” for another embodiment.
• Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in U.S. Pat. No. 6,936,491 issued to Partridge et al. and entitled “Microelectromechanical Systems Having Trench Isolated Contacts, and Methods of Fabricating Same”, filed on Jun. 4, 2003 and assigned Ser. No. 10/455,555 (hereinafter “Microelectromechanical Systems Having Trench Isolated Contacts Patent”). For the sake of brevity, the inventions described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent will not be repeated but will only be summarized. It is expressly noted, that the entire contents of the Microelectromechanical Systems Having Trench Isolated Contacts Patent, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• Other types of encapsulation, now known or later developed, including for example, but not limited to, other types of thin film encapsulation techniques and/or structures (see, for example, WO 01/77008 A1 and WO 01/77009 A1), may also be employed.
• The one ormore encapsulation layers154 may define one or more conductive regions, e.g.,conductive regions160,162,164,166, disposed superjacent one or more of the mechanical structures, e.g.,electrodes20,22,84,86, respectively, to facilitate electrical contact therewith. The one ormore encapsulation layers154 may further define one or more trenches, e.g.,trenches170,172,174,176, disposed about one or more of the conductive regions to electrically isolate the conductive regions, e.g.,conductive regions160,162,164,166, respectively, from one or more other portions of the micromachinedmechanical structure12. Insulating material may be deposited in one or more of the trenches, e.g.,trenches170,172,174,176, to form one or more isolation regions, e.g.,isolation regions180,182,184,186, respectively.
• The micromachined mechanical structure may further define aninsulation layer190 and aconductive layer192 disposed superjacent encapsulation layer(s)154. Theinsulation layer190 may provide electrical isolation betweenconductive layer192 and one or more other portions of the micromachinedmechanical structure12, as may be desired. Theconductive layer192 may define one or more conductive regions, e.g.,conductive regions200,202,204,206, that form part of the electrical connection to one or more of the mechanical structures, e.g.,electrodes20,22,84,86, respectively.
• FIGS. 4A-4J andFIGS. 5A-5J illustrate cross-sectional views of one embodiment of the fabrication of the micromachinedmechanical structure12 ofFIG. 2A, including one embodiment of encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• An exemplary method of fabricating or manufacturing a thin film encapsulatedMEMS10 is described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent. It has been determined that the methods and techniques described in the Microelectromechanical Systems Having Trench Isolated Contacts Patent provide a stable vacuum cavity that is well suited for use in association with the methods and structures disclosed herein. For the sake of brevity, those discussions and illustrations will not be repeated but will only be summarized. It is expressly noted, however, that the entire contents of the Microelectromechanical Systems Having Trench Isolated Contacts Patent, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• With reference toFIG. 4A andFIG. 5A, fabrication ofMEMS10 may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes19,20,22,84,86 andfuse89, and disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride.
• The mechanical structures, e.g.,electrodes19,20,22,84,86 andfuse89, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Field regions, e.g.,field regions94,95,96, and a firstsacrificial layer220 may be formed using well-known silicon-on-insulator fabrication techniques or well-known formation, lithographic, etching and/or deposition techniques using a standard or over-sized (“thick”) wafer (not illustrated).
• In some embodiments, one or more of the mechanical structures and/or one or more of the field regions are comprised of, for example, any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table, for example silicon, germanium, carbon; also combinations of these, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• With reference toFIG. 4B andFIG. 5B, following formation of the mechanical structures, e.g.,electrodes19,20,22,84,86 andfuse89, a secondsacrificial layer222, for example, silicon dioxide or silicon nitride, may be deposited and/or formed to secure, space and/or protect the mechanical structures, e.g.,electrodes19,20,22,84,86 andfuse89, during subsequent processing, including the encapsulation process.
• Referring toFIG. 4C andFIG. 5C, one or more openings, e.g.,openings140,142,144,146, may be etched and/or formed in secondsacrificial layer222 to facilitate subsequent electrical contact to one or more of the mechanical structures, e.g.,electrodes20,22,84,86, respectively. The openings, e.g.,openings140,142,144,146, may be provided using, for example, well known masking techniques (such as a nitride mask) prior to and during deposition and/or formation of secondsacrificial layer222, and/or well known lithographic and etching techniques after deposition and/or formation of secondsacrificial layer222.
• With reference toFIG. 4D andFIG. 5D, thereafter,first encapsulation layer154amay be deposited, formed and/or grown on secondsacrificial layer222. In one embodiment, the thickness offirst encapsulation154ain the region overlying secondsacrificial layer222 may be between 0.1.mu.m and 5.0.mu.m. The external environmental stress on, and internal stress offirst encapsulation layer154aafter etching secondsacrificial layer222 may impact the thickness offirst encapsulation layer154a. Slightly tensile films may self-support better than compressive films which may buckle.
• Referring toFIG. 4E andFIG. 5E, thefirst encapsulation layer154amay be etched to form passages or vents, e.g., vents224. In one exemplary embodiment, vents224 have a diameter or aperture size of between 0.1.mu.m to 2.mu.m. In some embodiments, the vents have a diameter or aperture size of about 1 um and are spaced apart by about 10 um.
• Referring toFIG. 4F andFIG. 5F, thevents224 permit etching and/or removal of at least selected portions of first and secondsacrificial layers220 and222, to release one or more portions of one or more of the mechanical structures, e.g.,electrodes19,20,22,84,86. As stated above, themass portion32 may define a plurality of openings, e.g., openings70 (FIG. 2C) to facilitate etching and/or removal of sacrificial material from beneath themass portion32.
• After the etching and/or removal of at least selected portions of first and secondsacrificial layers220,222, one or more areas of the mechanical structures, e.g.,electrodes19,20,22,84,86, may remain partially, substantially or entirely surrounded by portions of firstsacrificial layer220 and/or secondsacrificial layer222. For example, one or more portions of firstsacrificial layer220 may remain to define one or more insulation areas, e.g.,insulation areas109,110,112,114,116, to support one or more of the mechanical structures, e.g.,electrodes19,20,22,84,86, respectively, and/or to electrically isolate one or more of the mechanical structures, e.g.,electrodes19,20,22,84,86, respectively, from thesubstrate14. One or more portions of the firstsacrificial layer220 and/or the secondsacrificial layer222, e.g.,areas130,132,134,136, of secondsacrificial layer222, may remain to partially, substantially or entirely surroundcontact areas20a,22a84a,86aofelectrodes20,22,84,86, respectively.
• In this regard, one or more of the methods mentioned in the Microelectromechanical Systems Having Trench Isolated Contacts Patent may be employed. As mentioned in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the contact area may remain partially, substantially or entirely surrounded by portions of first and second sacrificial layers. For example, with reference toFIG. 4F of the Microelectromechanical Systems Having Trench Isolated Contacts Patent, while mechanical structures are released from their respective underlying oxide columns, a portion of second sacrificial layer (i.e., juxtaposed electrical contact area) may remain after etching or removing second sacrificial layer. Such portion of second sacrificial layer may function as an etch stop during later processing.
• With reference toFIG. 4G andFIG. 5G, after releasing one or more portions of the mechanical structures, e.g.,electrodes19,20,22,84,86,second encapsulation layer154bmay be deposited, formed and/or grown. Thesecond encapsulation layer154bmay be, for example, a silicon-based material (for example, a polycrystalline silicon or silicon-germanium), which is deposited using, for example, an epitaxial, a sputtering or a CVD-based reactor (for example, APCVD, LPCVD, or PECVD). The deposition, formation and/or growth may be by a conformal process or non-conformal process. The material may be the same as or different fromfirst encapsulation layer154a.
• With reference toFIGS. 4H-4I andFIGS. 5H-5I, one or more contact areas of one or more of the mechanical structures, e.g.,contact areas20a,22a,84a,86a, ofelectrodes20,22,84,86, respectively, may thereafter be dielectrically isolated from the surrounding conductor and/or semiconductor layers. For example, trenches, e.g.,trenches170,172,174,176, may be etched (seeFIG. 4H andFIG. 5H). As described below, an insulating material may be deposited in the trenches, e.g.,trenches170,172,174,176, to form dielectric isolation regions, e.g.,dielectric isolation regions180,182,184,186, respectively (SeeFIG. 41 andFIG. 51). The insulating material may be, for example, silicon dioxide, silicon nitride, BPSG, PSG, or SOG. The trenches, e.g.,trenches170,172,174,176, may include a slight taper in order to facilitate the formation of the dielectric isolation regions, e.g.,dielectric isolation regions180,182184,186, respectively.
• The insulatinglayer190 may be deposited, formed and/or grown on the exposed surface ofsecond encapsulating layer154bto provide insulation between the various surrounding conductive and/or semiconductor layers and the subsequent conductive layer. During deposition, formation and/or growth ofinsulation layer190, trenches may also be filled to form thedielectric isolation regions180,182,184,186. Thereafter,openings226 may be formed and/or etched ininsulation layer190, for example, using conventional etching techniques.Openings226 may facilitate electrical connection to contact areas of mechanical structures, e.g.,contact areas20a,22a,84a,86aofelectrodes20,22,84,86, respectively.
• Referring toFIG. 4J andFIG. 5J, theconductive layer192 may then be deposited and/or formed.Conductive layer192 may be patterned to provide one or more conductive regions, e.g.,conductive regions200,202,204,206, respectively, to provide electrical connections to one or more contact areas of one or more of the mechanical structures, e.g.,contact areas20a,22a,84a,86a, ofelectrodes20,22,84,86, respectively.
• Patterning ofconductive layer192 may begin, for example, by applying a layer of photoresist over theconductive layer192. The photoresist may thereafter be patterned (e.g., portions of the photoresist are exposed and developed away) to expose the portions of theconductive layer192 that are to be removed. An etch may subsequently be performed wherein the photoresist covered portions of the conductive layer192 (i.e., the portions of the conductive layer defining the conductive regions192) are left intact and the other portions of theconductive layer192 are removed.
• In this embodiment,conductive layer192 comprises any type of conductive material, for example, metal (e.g., aluminum, chromium, gold, silver, molybdenum, platinum, palladium, tungsten, titanium, copper, and/or an alloy of one or more thereof, non-metal and/or conductive adhesive material. In some embodiments,conductive layer192 comprises one or more portions that are sputtered and, if necessary patterned. In addition, a shadow mask technology may be employed to deposit and/or patternconductive layer192.
• Fluid may be disposed within the chamber. The state of the fluid within chamber150 (for example, the pressure), after deposition and/or formation of chamber may be determined using conventional techniques and/or using those techniques described and illustrated in U.S. Patent Application Publication 20040183214 of non-provisional patent application entitled “Electromechanical System having a Controlled Atmosphere, and Method of Fabricating Same”, which was filed on Mar. 20, 2003 and assigned Ser. No. 10/392,528 (hereinafter “the Electromechanical System having a Controlled Atmosphere Patent Application Publication”). For the sake of brevity, all of the inventions regarding controlling the atmosphere withinchamber150 which are described and illustrated in the Electromechanical System having a Controlled Atmosphere Patent Application Publication will not be repeated here. It is expressly noted, however, that the entire contents of the Electromechanical System having a Controlled Atmosphere Patent Application Publication, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• As stated above, in this embodiment,insulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere contained within thechamber150 are sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored (relative to any requirements, in such embodiments, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge).
• In that regard, as stated above, some embodiments may be able to tolerate more contamination, less electrical isolation, more leakage and/or more drain of electrical charge than other embodiments. To that effect, as stated above, the term “sufficiently free” means “sufficiently free” relative to any requirements, in any given embodiment, that relate, directly and/or indirectly, to contamination. For example, a surface and/or atmosphere that is not “sufficiently contaminant free” for one embodiment may nonetheless be “sufficiently contaminant free” for another embodiment.
• In some embodiments, the surfaces on theinsulation areas109,110,112,114,116,130,132,134,136, and the atmosphere within thechamber150 are provided sufficiently free of surface contaminants by removing the at least selected portions of first and secondsacrificial layers220,222 and sealing the chamber using techniques that leave the surfaces of the remaining portions, e.g.,insulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere within thechamber150 sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored.
• In this regard, it has been determined that the surfaces on theinsulation areas109,110,112,114,116,130,132,134,136, and the atmosphere within thechamber150 may be provided sufficiently free of surface contaminants by removing the at least selected portions of first and secondsacrificial layers220,222 and subsequently sealing the chamber using technique(s) set forth in (1) Electromechanical System having a Controlled Atmosphere Patent Application Publication, (2) Microelectromechanical Systems Having Trench Isolated Contacts Patent, (3) U.S. Patent Application Publication No. 20040248344 of non-provisional patent application entitled “Microelectromechanical Systems, and Method of Encapsulating and Fabricating Same”, which was filed on Jun. 4, 2003 and assigned Ser. No. 10/454,867 (hereinafter “Microelectromechanical Systems and Method of Encapsulating Patent Application Publication”) and/or (4) U.S. Pat. No. 6,952,041 issued to Lutz et al. and entitled “Anchors for Microelectromechanical Systems Having an SOI Substrate, and Method for Fabricating Same”, which was filed on Jul. 25, 2003 and assigned Ser. No. 10/627,237 (hereinafter the “Anchors for Microelectromechanical Systems Patent”), for example, as described above with respect toFIGS. 4A-4J andFIGS. 5A-5J. The entire contents of the Electromechanical System having a Controlled Atmosphere Patent Application Publication, the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and the Anchors for Microelectromechanical Systems Patent, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• Thus some embodiments, employ technique(s) set forth in (1) Electromechanical System having a Controlled Atmosphere Patent Application Publication, (2) Microelectromechanical Systems Having Trench Isolated Contacts Patent, (3) Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or (4) Anchors for Microelectromechanical Systems Patent, for example, as described above with respect toFIGS. 4A-4J andFIGS. 5A-5J.
• Some embodiments have the ability to supply electrical charge to the first electrode19 (and/or other portion(s) of micromachined mechanical structure12) and to store at least a portion of the electrical charge on the electrode19 (and/or other portion(s) of micromachined mechanical structure12) for a period of at least ten years.
• In such embodiments,insulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere contained within thechamber150 are sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge (relative to any requirements, in such embodiments, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge), so as to help provide the ability to store at least a portion of the electrical charge for a period of at least ten years.
• In that regard, some of such embodiments employ technique(s) set forth in (1) Electromechanical System having a Controlled Atmosphere Patent Application Publication, (2) Microelectromechanical Systems Having Trench Isolated Contacts Patent, (3) Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or (4) Anchors for Microelectromechanical Systems Patent, for example, to remove the at least selected portions of first and secondsacrificial layers220,222 and subsequently seal the chamber so as to leave the surfaces of the remaining portions, e.g.,insulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere within thechamber150 sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge for such embodiment (relative to any requirements, in such embodiments, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge), so as to help provide the ability to store at least a portion of the electrical charge for a period of at least ten years.
• Some other embodiments may not provide the ability to store at least a portion of the electrical charge for a period of at least ten years. For example, as further described below, in some applications, there is no need to store at least a portion of the electrical charge for ten years. In that regard, some applications require the ability to store at least a portion of the electrical charge for at least one day. To that effect, some embodiments provide the ability to store at least a portion of the electrical charge for a period of at least one day. Some other applications require the ability to store at least a portion of the electrical charge for a period of at least one month. To that effect, some embodiments provide the ability to store at least a portion of the electrical charge for a period of at least one month. Some other applications require the ability to store at least a portion of the electrical charge for a period of at least one year. To that effect, some embodiments provide the ability to store at least a portion of the electrical charge for a period of at least one year.
• In such embodiments, theinsulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere contained within thechamber150 are sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge, (relative to any requirements, in the respective embodiment, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge), so as to help provide the ability to store at least a portion of the electrical charge for at least the period of time required in the respective embodiment, i.e., at least one day, at least one month and/or at least one year.
• To that effect, some of such embodiments employ technique(s) set forth in (1) Electromechanical System having a Controlled Atmosphere Patent Application Publication, (2) Microelectromechanical Systems Having Trench Isolated Contacts Patent, (3) Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or (4) Anchors for Microelectromechanical Systems Patent, for example, to remove the at least selected portions of first and secondsacrificial layers220,222 and subsequently seal the chamber so as to leave the surfaces of the remaining portions, e.g.,insulation areas109,110,112,114,116,insulation areas130,132,134,136, and the atmosphere within thechamber150 sufficiently free of surface contaminants that would otherwise result in excessive reduction in electrical isolation, excessive surface leakage and/or excessive drainage of the electrical charge (relative to any requirements, in the respective, that relate, directly and/or indirectly, to contamination, electrical isolation, leakage and/or drainage of the electrical charge), so as to help provide the ability to store at least a portion of the electrical charge for at least the period of time required in the respective embodiment, i.e., at least one day, at least one month and/or at least one year.
• Other types of encapsulation, now known or later developed, may be employed in addition to and/or in lieu of the encapsulation described above.
• FIGS. 6A-6D illustrate stages that may be employed in supplying, storing and/or trapping charge on thefirst electrode19 of the transducer16 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention. Referring toFIG. 6A, in a first stage, one or more of the first andsecond electrodes84,86 are electrically connected to a first power source, e.g., afirst voltage source300. The first power source, e.g.,first voltage source300, supplies an electric current302 that flows through one or more of theelectrodes84,86 and thefuse89 to supply charge to thefirst electrode19 of the transducer (or other mechanical structure(s) on which charge is to be stored). The charge supplied to thefirst electrode19 of the transducer16 (or other mechanical structure(s) on which charge is to be stored) may cause an increase in the voltage thereof.
• The charge supplying process may continue until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, first power source, e.g.,first voltage source300, supplies a voltage that is equal to the voltage desired for electrode19 (or other mechanical structure(s) on which charge is to be stored), and the charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the first power source, e.g.,voltage source300, and then stops. As further described hereinafter, in some embodiments, the desired voltage is within a range of from about 100 volts to about one thousand volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded).
• The charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current302 may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• After a desired amount of charge has been supplied, it may be desirable to “blow” (e.g., melt and/or rupture), one or more portions of thebreakable link88, e.g., fuse89, so as to break the connection between theelectrodes84,86 and theelectrode19 of the transducer (or other mechanical structure(s) on which charge is to be stored) and thereby disconnect the first power source, e.g.,first voltage source300, from such electrode19 (or other mechanical structure(s) on which charge is to be stored).
• To that effect, and with reference toFIG. 6B, a second power source, e.g., asecond voltage source304, may be connected to one or more of the first andsecond electrodes84,86. The second power source, e.g.,second voltage source304, may be used to supply an electric current306 that flows throughelectrode84, one or more portions offuse89 andelectrode86. The current306 cause one or more portions of thefuse89 to dissipate power and produce heat.
• With reference toFIG. 6C, if the heat is of sufficient magnitude and/or duration, one or more portions of thefuse89, e.g.,first portion90, reaches or exceeds a temperature at which such portion(s) “blow” (e.g., melt and/or rupture), thereby breaking the connection between theelectrodes84,86 and the electrode19 (or other mechanical structure(s) on which charge is to be stored) and disconnecting the first power source, e.g.,first voltage source300, from the electrode19 (or other mechanical structure(s) on which charge is to be stored). With reference toFIG. 6D, thereafter, micromachinedmechanical structure12 may be disconnected from the first power source, e.g., thefirst voltage source300, and the second power source, e.g., thesecond voltage source304.
• Unless specified otherwise, the term “breaking” includes but is limited to suspending, interrupting, halting, stopping, melting, blowing (e.g., melting, rupturing and/or exploding), fracturing, shattering, bursting, and/or destroying. Likewise, the term “break” includes but is limited to suspend, interrupt, halt, stop, melt, blow (e.g., melt, rupture and/or explode), fracture, shatter, burst, and/or destroy. Breaking may be reversible or irreversible and/or a combination thereof. Irreversible breaking includes fracturing, shattering, bursting, melting, blowing (e.g., melting, rupturing and/or exploding) and/or destroying.
• Notably, at the end of the charge supplying process employed in the embodiment ofFIGS. 6A-6D, the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) is electrically isolated from all other electrically conductive structures within the chamber and outside of the chamber.
• In some embodiments, an electrical isolation of at least ten teraohms or another a high DC resistance is provided between thefirst electrode19 and other electrically conductive structures within the chamber including, for example, each of theother electrodes20,22 and theelectrodes84,86 temporarily connected to the power source during the charge supplying process. Such a configuration helps reduce the possibility of excessive surface leakage within the chamber and/or leakage throughelectrodes84,86 and out the chamber that could otherwise lead to excessive drain of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored.
• In addition, as stated above, at the end of the charge supplying process employed in this embodiment, the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) is also electrically isolated from electrically conductive structures outside the chamber. As stated above, structures outside the chamber may have more contamination and/or greater potential for leakage current and/or drain than structures inside the chamber. Thus, providing electrical isolation from conductive structures outside of the chamber may significantly reduce leakage current and/or drain.
• In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided, thereby reducing the possibility of excessive leakage through the one or moremechanical structures82 to points outside the chamber that could otherwise lead to excessive drain of the electrical charge on the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored).
• Notably, some embodiments may not need to electrically isolate the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored and/or trapped) from electrically conductive structures outside the chamber. For example, the leakage and/or drain without such isolation may not be excessive for some embodiments. In some such embodiments, a permanent electrical connection (and/or other configuration) may be employed instead of a breakable link. Alternatively, the one or moremechanical structures82 may be eliminated and first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) may be provided with a contact area electrically connected to one or more electrically conductive structures outside the chamber.
• In some embodiments, the first power source, e.g., thefirst voltage source300, may include a current limiter (not shown) to limit the magnitude of the electric current302 to a magnitude that is low enough to reduce the possibility of blowing (e.g., melting and/or rupturing) thefuse89 before a desired amount of charge has been supplied to the electrode19 (or other mechanical structure(s) on which charge is to be stored).
• Any number and type of considerations may be employed in determining the amount of charge to be supplied to the electrode19 (or other mechanical structure(s) on which charge is to be stored). For example, it may be desirable to supply an amount of charge that is sufficient to facilitate a desired level of performance (e.g., efficiency, signal to noise ratio, accuracy and/or speed) on the part of theMEMS10. In some embodiments, for example,MEMS10 may not provide a desired level of performance (e.g., efficiency and/or signal to noise ratio), in whole or in part, unless a sufficient amount of charge is supplied to the electrode19 (or other mechanical structure(s) on which charge is to be stored). Thus, for example, if the transducer is employed as an energy harvesting device, it may be advantageous to supply enough electrical charge to allow the transducer to generate enough electrical energy to allow the device to meet a desired level of performance. If a transducer is employed as sensor, it may be advantageous to supply enough electrical charge to allow the transducer to meet the desired level of performance of the sensor.
• Performance requirements may vary from application to application. For example, a device having a sensor and an interface circuit for wireless communication may require twice as much, or more, electrical power than a similar device without wireless communication. Moreover, the amount of power required by a device may depend greatly on the type of sensor and/or the sample rate in the application. Some sensors require more power than other sensors and increasing the sample rate of a given sensor generally increases the amount of power required by that sensor. Some applications require a higher sample rate than others. A pollution monitoring application, for example, may employ a sample rate of one sample per minute or one sample per ten minutes. A tire monitoring application may employ a sample rate of one sample per second or one sample per minute. On the other hand, an airbag application may employ a sample rate of one thousand samples per second or higher.
• Another possible consideration is breakdown voltage. Some gaps and structures (e.g., insulators and/or non-conductive structures) have a breakdown voltage associated therewith. Undesirable consequences (e.g., arcing and/or breakdown) can occur if the voltage across a gap or structure exceeds the breakdown voltage of such gap or structure. Thus, it may be advantageous to limit the stored charge to an amount that is small enough to ensure that the voltage across any gap or structure does not exceed the breakdown voltage thereof. In some embodiments, insulators and/or non conductive structures have a dielectric strength of 1.times.10.sup.9 volts/meter, a thickness of 1.times.10.sup.-6 meters and a breakdown voltage of approximately 1000 volts. In some embodiments, the relationship between the breakdown voltage of an insulator and/or non conductive structure, the dielectric strength of the insulator and/or non conductor and the thickness of the insulator and/or non conductor is as follows:
• 
  breakdown voltage=dielectric strength times thickness  (1)
• where breakdown voltage is expressed in volts,
• dielectric strength is expressed, for example, in volts/meter and
• thickness is expressed, for example, in meters.
• Even if the breakdown voltage is not exceeded, a voltage across an insulator and/or non-conductive structure may cause the properties thereof to degrade overtime. Thus, if a MEMS is to operate for a long period of time, it may be desirable to limit the stored charge to an amount that is small enough to ensure that the properties of the insulator and/or non conductive structure do not degrade excessively over the desired operational life of the MEMS. In some embodiments, it may be desirable to limit the stored charge to an amount that is small enough to ensure that the voltage across an insulator and/or non conductive structure does not exceed a small fraction, e.g., 10 percent, of the breakdown voltage of thereof. For example, if the breakdown voltage of an insulator and/or non conductive structure is 1000 volts, and the desired operational lifetime of the MEMS is 10 years, it may be desirable to limit the stored charge to an amount that is small enough to ensure that the voltage across such insulators and/or non conductive structures does not exceed 100 volts (i.e., 0.1.times.1000 volts). In some embodiments, it may be possible to take advantage of the fact that leakage may cause the amount of electrical charge to decrease over time.
• Other considerations may include the distance and/or the attraction force between structures, e.g., (1) the distance and/or the attraction force between thesecond electrode20 and thefirst electrode19 and (2) the distance and/or the attraction force between thethird electrode22 and thefirst electrode19. In some embodiments, for example, if an excitation (e.g., vibrational energy) causes one of the structures to move toward another structure by an amount greater than one third of the distance separating the structures in the absence of the excitation, the attraction force between such structures may increase to a magnitude that causes the structure to continue to move toward the other structure until the two structures contact one another. Thus, the attractive force may have the effect of placing limits on one or more of the parameters to be selected, for example, but not limited to, the maximum amount of charge, the minimum spring constant and/or the minimum distance between structures (e.g., the minimum distance between thesecond electrode20 and thefirst electrode19, the minimum distance between thethird electrode22 and the first electrode19). In some embodiments, for example, the design of the micromachined mechanical structure ensures that a maximum expected excitation (e.g., vibrational energy) does not cause the distance between structures to decrease by an amount greater than one third of the distance separating the structures in the absence of the excitation.
• Another possible consideration is the electrical isolation. In some embodiments, for example, the electrical isolation affects whether electrical charge drains from electrode19 (and/or any other portion on which electrical charge is stored) over time, and if so, the rate of at which the charge drains. Increasing the electrical isolation may reduce the rate at which charge drains, if any, from electrode19 (and/or any other portion on which electrical charge is stored). Decreasing the electrical isolation may increase the rate of decrease. In some embodiments, the rate of decrease is time dependent. For example, in some embodiments, the magnitude of the voltage on the first electrode19 (and/or any other portion on which electrical charge is stored) is time dependent and in accordance with the following equation:
• 
  V=V.sub.0e.sup.−t/RC  (2)
• where V.sub.0 is the magnitude of the voltage onelectrode19, expressed in volts, at the time that electrode19 is initially electrically isolated,
• it is the number of seconds since electrically isolating thefirst electrode19,
• R is the magnitude of the insulation resistance expressed in ohms,
• C is the magnitude of the capacitance, expressed in farads.
• Another consideration is the duration of the application. In that regard, some applications have a duration of ten years. For example, the useful life of some automobile tires and/or other automobile components is ten years, depending on the conditions and the number of miles driven each year. If a sensor is to be employed to monitor a condition of such tires, it is desirable to employ a sensor having a useful life that is as least as long as that of the tires. Thus, in some embodiments, it is desirable to have the ability to store at least a portion of the electrical charge for a period of at least ten years.
• However, many applications have a duration of less than ten years. Some applications may involve sensing conditions during an event or activity of less than ten years and/or a characteristic of a device having a useful life of less than ten years. In either of such applications, there may be no need to store charge for ten years. Rather, it may be sufficient to store at least a portion of the electrical charge for period at least as long as the duration of such applications.
• Some applications have a duration of up to five years. In the field of consumer electronics, for example, some devices (e.g., example, laptop computers, portable data assistants (PDA's) and calculators) may be replaced at least every five years, for example, because the devices are worn out and/or to take advantage of a new design that has become available. If a sensor is to be employed in such an application, there may be no need for a sensor having a useful life of ten years. However, it would be advantageous to have the ability to employ a sensor having a useful life that is at least five years, and/or at least as long as the expected life of the device. Thus, if the sensor employs stored electrical charge, it would be desirable to have the ability to store at least a portion of the electrical charge for a period of at least five years or at least as long as the expected life of the component.
• Some applications have a duration of one year or less. Some disposable devices, for example, are replaced annually, semi-annually, or more frequently because the devices are worn out and/or because better devices are available. In the field of auto racing, for example, the useful life of many components (e.g., tires) is often less than one year. Indeed, in professional auto racing circuits, the useful life of tires is often less than one day or race. Moreover, new tire designs may become available each year or season. If a sensor is to be employed in such an application, for example, to monitor a condition relating to a tire, there may be no need for a sensor having a useful life of ten years. However, it would be advantageous to have the ability to employ a sensor having a useful life that is at least one year, and/or at least as long as the application or the expected life of the component. Thus, if the sensor employs stored electrical charge, it would be desirable to have the ability to store at least a portion of the electrical charge for a period of at least one year or at least as long as the duration of the application or the expected life of the component.
• Some applications last a week or less. For example, in the field of trucking, i.e., transporting goods on trucks, shipping time is usually one week or less. In the field of overnight shipping, shipping time is typically less than one day. If a sensor is to be employed in such applications, for example, to monitor conditions (e.g., conditions relating to the shipping container and/or goods being shipped) during the shipment (via truck or overnight), it would be advantageous to employ a sensor having a useful life that is at least one week or at least as long as the duration of the application (e.g., shipment or other activity). If the sensor employs stored electrical charge, it would be advantageous to have the ability to store at least a portion of the electrical charge for a period of at least one week or at least as long as the duration of the application (e.g., shipment or other activity).
• The supplying of charge may be carried out at any time(s). In some embodiments, the supplying of charge is carried out by a manufacturer of the part (and/or a manufacturer of a device that employs the part) before shipping the part (or a device employing the part) to a customer. In some embodiments, the supplying of charge is carried out by a purchaser or an end user of the part (or a device that employs the part) before, or at the time that the part (or a device that employs the part) is put into service in an application. In some embodiments, the supplying of charge is carried out during or after the application and/or in any combination of any of the above times.
• If the supplying of charge is to be carried out by the manufacturer, e.g., at a factory, it may be desirable to have the ability to store charge for a period of at least one month (or some other desired period of time), even if the duration of the application is as short as a day or a week. Providing the ability to store charge for a period of at least one month (or another desired period of time) helps make it possible for a manufacturer to complete processing of the part (and/or a device employing the part), if needed, and to ship the part (or a device employing the part) to a distributor and/or end user, for use in such application, before the period expires.
• As stated above, some embodiments employ a capacitance in a range of from about one femptofarad to about one nanofarad and/or a voltage in a range of from about one volt to about one thousand volts. In some embodiments, the amount of electrical charge is a range of from one femptocoulomb (one volt on a capacitance of one femptofarad) to about one micro coulomb (one thousand volts on a capacitance of one nanofarad). An equation relating charge, voltage and capacitance is as follows:
• 
  Q=CV  (3)
• where
• Q is the amount of charge expressed in coulombs,
• C is the magnitude of the capacitance expressed in farads and
• V is the magnitude of the voltage expressed in volts.
• Some embodiments supply the greatest possible amount of charge, limited, if appropriate, by one or more of the considerations set forth above, e.g., breakdown voltage, deratings, if any, and/or the available area and/or volume to provide the capacitance.
• In some embodiments, it is advantageous (e.g., due to performance considerations) to have the ability to store a large percentage (i.e., at least 60%-100%) of the electrical charge supplied to electrode19 (and/or any other portion on which electrical charge is stored). However, in some embodiments, it is satisfactory and/or desirable (e.g., for derating in long applications and/or controlling manufacturing cost) to have the ability to store a smaller percentage (i.e., at least 20% to 50%) or at least a small percentage of the electrical charge initially supplied. In some embodiments, it is satisfactory and/or desirable (e.g., for derating in long applications and/or controlling manufacturing cost) to retain a smaller percentage (i.e., 0.01% to 10%) or at least a small percentage of the electrical charge initially supplied.
• In some embodiments, it may be desirable to test each part to determine the amount of electrical charge stored therein and/or the rate of any decrease in electrical charge, and to sort, sell and/or use the parts based on the results thereof. For example, each part may be sorted based on whether it has a high rate of decrease or a low rate of decrease. Parts having a high rate of decrease may be sold for and used in applications of short duration. Parts having a low rate of decrease may be sold for and used in applications of long duration.
• FIGS. 7A-7C illustrate plan views of a portion of the micromachinedmechanical structure12 showing stages that may be employed in the operation of the transducer, in accordance with certain aspects of the present invention. Referring toFIG. 7A, as stated above, in the absence of an excitation (e.g., vibration) the movablemechanical structure28 of thefirst electrode19 may be stationary and disposed at a position approximately centered between thesecond electrode20 and thethird electrode22. With the movablemechanical structure28 at such position, the width of thefirst gap46 may be approximately equal to the width of thesecond gap50. The charge stored on thefirst electrode19 results in a first voltage V1 across the first capacitance (e.g., defined by thesecond electrode20 and the first electrode19) and a second voltage V2 across the second capacitance (e.g., defined by thethird electrode22 and the first electrode19). A relationship between charge, voltage and capacitance is set forth by equation (2) set forth above.
• With themovable structure28 stationary and centered between thesecond electrode20 and thethird electrode22, the first voltage V1 and the second voltage V2 may be equal to and opposite one another (or approximately equal to and opposite one another).
• The first and second voltages V1 and V2 result in laterally directed, electrostatic forces on themovable structure28. With themovable structure28 stationary and centered, as shown, the laterally directed electrostatic force due to the voltage V1 across the first capacitance may be equal to and opposite (or approximately equal to and opposite) the laterally directed, electrostatic force due to the voltage V2 across the second capacitance, so that the net electrostatic force on themovable structure28 in the lateral direction may be equal to zero.
• With reference toFIG. 7B, providing an excitation (e.g., vibration) having a lateral component, e.g.,lateral component320, causes the movablemechanical structure28 ofelectrode19 to begin to move in a lateral direction, e.g.,lateral direction322. For example, if thelateral component320 is directed toward thethird electrode22, the movablemechanical structure28 begins to move in adirection322 toward thesecond electrode20, as shown, such that the size of thefirst gap46 decreases and the size of thesecond gap50 increases. The decrease in the size of thefirst gap46 causes an increase in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19). Because electrical charge is trapped on thefirst electrode19, the decrease in the size of thefirst gap46 also causes an electrical current out of thesecond electrode20, thereby decreasing the voltage of the first electrode and increasing the charge differential and the voltage differential across the first capacitance. The increase in the size of thesecond gap50 causes a decrease in the magnitude of the second capacitance (e.g., defined by thethird electrode22 and first electrode19). Because electrical charge is trapped on thefirst electrode19, the increase in the size of thesecond gap50 also causes an electrical current into thethird electrode22, thereby increasing the voltage of the second electrode and decreasing the charge differential and the voltage differential across the second capacitance.
• With reference toFIG. 7C, if thelateral component320 is directed toward thesecond electrode20, the movablemechanical structure28 begins to move in adirection324 toward thethird electrode22, such that the size of thefirst gap46 increases and the size of thesecond gap50 decreases. The increase in the size of thefirst gap46 causes a decrease in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19). Because electrical charge is trapped on thefirst electrode19, the increase in the size of thefirst gap46 also causes an electrical current into thesecond electrode20, which in turn decreases the charge across the first capacitance. The decrease in the size of thesecond gap50 causes an increase in the magnitude of the second capacitance (e.g., defined by thethird electrode22 and the first electrode19). Because electrical charge is trapped on thefirst electrode19, the decrease in the size of thesecond gap50 also causes and an electrical current out of thethird electrode22, which in turn increases the charge across the second capacitance.
• If thetransducer16 is employed as an energy harvesting device, one or more portions of the electrical energy generated by thetransducer16 may be supplied, directly and/or indirectly, to one or more circuits and/or devices, and/or used, directly and/or indirectly, in powering one or more portions of one or more circuits and/or devices. For example, one or more of the voltages and/or one or more of the currents generated by thetransducer16 may be supplied, directly or indirectly, to one or more circuits and/or devices, and/or used, directly and/or indirectly, in powering one or more portions of one or more circuits and/or devices. In some embodiments, the electrical energy supplied by thetransducer16 is in the form of AC power, e.g., one or more AC voltages and/or currents.
• Many types of MEMS and/or miniature devices (e.g., miniature sensors and/or miniature systems) require electrical power to operate and thus typically receive power from an external power source, for example, in the form of an AC drive signal used to generate a DC voltage to power the circuits and/or devices of the MEMS and/or miniature device. In some embodiments, the power fromtransducer16 is sufficient to operate a MEMS and/or a miniature device and thus there may be no need for additional power e.g., from an external power source and/or battery. For example, the power from transducer may be sufficient to power each device and/or circuit of the MEMS and/or miniature device that requires such power.
• In some other embodiments, the power from thetransducer16 may not be sufficient to eliminate the need for additional power from an external power source and/or battery. Nonetheless, the power from the transducer may reduce the amount power required from an external power source and/or a battery. That is, the amount of power required from an external power source and/or a battery may be less than the amount of power that would be required from the external power source and/or battery if the MEMS and/or miniature device did not receive power from thetransducer16. Reducing and/or eliminating the need for power from an external power source and/or a battery, may help make it possible to employ MEMS and/or miniature devices in additional applications and/or may help improve the performance of MEMS and/or miniature devices in existing applications.
• In some embodiments, the amount of power generated by the transducer depends at least in part on the amount of energy supplied thereto, e.g., the amount of vibrational energy supplied to the transducer. In some embodiments, the transducer receives vibrational energy and has an efficiency that may be expressed in terms of power/acceleration. In some such embodiments, the efficiency of the transducer may be in a range of from 10 nanowatts/(1 m/s.sup.2) (i.e., 10 nanowatts/g) to 1 microwatt/1 m/s.sup.2 (i.e., 1 microW/g).
• If thetransducer16 is employed as a sensor (e.g., a vibration sensor and/or accelerometer), one or more portions of the electrical energy generated by thetransducer16 may be supplied, directly and/or indirectly, to one or more circuits and/or devices, and/or used directly and/or indirectly, as an indication of one or more physical quantities (e.g., vibration and/or acceleration) sensed by thetransducer16. For example, one or more of the electrical signals (e.g., one or more of the voltages (e.g., the voltage across the first and/or second capacitance) generated by thetransducer16 and/or one or more of the currents (e.g., the current into and/or out of the first and/orsecond electrodes19,20)) generated by thetransducer16, may be supplied, directly or indirectly, to one or more circuits and/or devices and/or employed as an indication of the one or more physical quantities (e.g., vibration and/or acceleration) sensed by thetransducer16. In some embodiments thetransducer16 may operate without electrical power, for example, as described above. In some other embodiments,transducer16 may be a type of transducer that does not operate fully without electrical power.
• The amount of the movement observed in the movable structure of thefirst electrode19 may depend at least in part on the magnitude of the excitation (e.g., vibrational energy) applied to the micromachinedmechanical structure12, the spring constant of thespring portion30 and the mass of themass portion32. In some embodiments, the mass of themass portion32 is in a range of from 0.01 milligram or about 0.01 milligram to one milligram or about one milligram.
• In some embodiments, it may be advantageous to employ aspring portion30 and amass portion32 that cause the movablemechanical structure28 to have a resonant frequency equal to, or approximately equal to, a frequency of the excitation (e.g., vibrational energy to be converted to electrical energy) to be converted to electrical energy, in order to improve and/or maximize the efficiency of the transducer. The resonant frequency of a harmonic oscillator employing a spring and a mass may be expressed by the equation: resonant frequency=(k/m), where k is equal to the spring constant and m is equal to the mass. Thus, the resonant frequency of the movablemechanical structure28 may be adjusted by increasing/decreasing the spring constant of thespring portion30 and/or by increasing/decreasing the mass of themass portion32. The spring constant may be decreased by increasing thelength62 of thespring portion30 and/or by decreasing thewidth64 of the spring portion30 (or portions thereof. The spring constant may be increased by decreasing thelength62 of thespring portion30 and/or by increasing thewidth64 of the spring portion30 (or portions thereof). The mass of themass portion32 may be adjusted by changing the dimensions and/or density of one or more portions of themass portion32.
• However, there is no requirement to employ a movablemechanical structure28 having a resonant frequency equal to the frequency of the excitation (e.g., vibrational energy to be converted to electrical energy). For example, some embodiments may have one or more constraints that preclude a resonant frequency equal to the frequency of the excitation. For example, it may not be possible to increase the length of thespring portion30 and/or the dimensions or density of themass portion32 without an unacceptable increase in the size of theMEMS10 and/or the cost associated therewith.
• Thus, some embodiments employ a movablemechanical structure28 having a resonant frequency greater than the frequency of the excitation (e.g., vibrational energy to be converted to electrical energy). In some embodiments, the frequency of the excitation is less than or equal to 100 Hertz (Hz) and the resonant frequency of the movablemechanical structure28 is greater than 100 Hz, for example, in a range from greater than 100 HZ but less than or equal to 1000 Hz. Some other embodiments employ a movable structure having a resonant frequency that is less than the frequency of the excitation.
• Some embodiments may employ a movablemechanical structure28 having more than one resonant frequency. For example, some embodiments may employ more than one spring portion and/or more than one mass portion arranged in and/or a geometric shape now know or later developed that includes provides the movablemechanical structure28 with more than one spring constant and/or more than one mass.
• Some embodiments may be exposed to more than one excitation frequency. In such embodiments, the movablemechanical structure28 may have one or more resonant frequencies equal to one or more of the excitation frequencies, one or more resonant frequencies greater than one or more of excitation frequencies and/or one or more resonant frequencies less than one or more of excitation frequencies.
• FIG. 8A illustrates a graphical representation of the magnitude of the first gap, the magnitude of the second gap, the current into the first electrode, the current into the second electrode, the voltage of the first electrode, the voltage of the second electrode, the voltage across the first capacitance and the voltage across the second capacitance, under steady state conditions, for one embodiment in which micromachinedmechanical structure12 has a mechanical time constant that is greater than its electrical time constant and a resistive load, e.g., represented as RL, provided between the first andsecond electrodes20,22 of thetransducer16. In this embodiment, the output voltage, Vout, is defined as the voltage of thesecond electrode20 minus the voltage of thethird electrode22. The output current, Iout, is defined as the current out of thesecond electrode20.
• FIG. 8B illustrates a graphical representation of Vout and Iout for the embodiment of the micromachined mechanical structure illustrated inFIG. 8A, under steady state conditions, according to certain aspects of the present invention.
• With reference toFIG. 8A andFIG. 8B, at a time t1, the magnitude of thefirst gap46 is at a maximum value, the current into the first electrode is zero, the voltage of the first electrode is at a maximum value and the voltage across the first capacitance is at a minimum value. In addition, at time t1, the magnitude of thesecond gap50 is at a minimum value, current into the second electrode is zero, the voltage of the second electrode is at a minimum value and the voltage across the second capacitance is at a maximum value. As a result, at time t1, the voltage Vout is at a maximum value and the current Iout is zero.
• At a time t2, the magnitude of thefirst gap46 is at a midpoint between a minimum value and the maximum value, the current out of the first electrode is at a maximum value, the voltage of the first electrode is at a midpoint between a minimum value and the maximum value and the voltage across the first capacitance is at a midpoint between the minimum value and a maximum value. In addition, at time t2, the magnitude of thesecond gap50 is at a midpoint between the minimum value and a maximum value, the current into the second electrode is at a maximum value, the voltage of the second electrode is at a midpoint between the minimum value and a maximum value and the voltage across the second capacitance is at a midpoint between a minimum value and the maximum value. As a result, at time t2, the voltage Vout is zero and the current Iout is at a maximum value.
• At a time t3, the magnitude of thefirst gap46 is at the minimum value, the current into the first electrode is zero, the voltage of the first electrode is at the minimum value and the voltage across the first capacitance is at the maximum value. In addition, at time t3, the magnitude of thesecond gap50 is at the maximum value, current into the second electrode is zero, the voltage of the second electrode is at the maximum value and the voltage across the second capacitance is at the minimum value. As a result, at time t3, the voltage Vout is at a minimum value and the current Iout is zero.
• At a time t4, the magnitude of thefirst gap46 is at the midpoint between the minimum value and the maximum value, the current into the first electrode is at a maximum value, the voltage of the first electrode is at the midpoint between the minimum value and the maximum value and the voltage across the first capacitance is at the midpoint between the minimum value and the maximum value. In addition, at time t4, the magnitude of thesecond gap50 is at the midpoint between the minimum value and the maximum value, the current out of the second electrode is at a maximum value, the voltage of the second electrode is at the midpoint between the minimum value and the maximum value and the voltage across the second capacitance is at the midpoint between the minimum value and the maximum value. As a result, at time t4, the voltage Vout is zero and the current Iout is at a maximum negative value.
• With reference toFIG. 9A, in some instances, the material comprising thesecond encapsulation layer154bmay deposit, form or grow over surfaces in chamber150 (for example, surfaces ofelectrodes20,22, surfaces ofportions30,32 ofelectrode19 and surfaces of field area94) as the chamber is sealed or encapsulated. In those instances where the material comprising a second or subsequent encapsulation layer (for example,second encapsulation layer154b) deposits, forms or grows over selected surfaces of the structures in chamber150 (see for example, surfaces ofelectrodes20,22, surfaces ofportions30,32 ofelectrode19 and surfaces of field area94) aschamber150 is sealed or encapsulated, it may be advantageous to design and fabricate mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) to account for the deposition, formation or growth of theadditional material154b′. In some embodiments, the thickness of theadditional material154b′ on the surfaces of mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) may be approximately equal to the width or diameter ofvent224. In some other embodiments, the thickness of theadditional material154b′ on the surfaces of mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) may be less than the width or diameter ofvent224. In some embodiments, theadditional material154b′ may have a first thickness on one or more surfaces of the mechanical structures and a different thickness on one or more other surfaces of the mechanical structures. For example, the thickness of theadditional material154b′ on a particular surface may be inversely proportional to the distance between the surface and thenearest vent224. Accordingly, in one set of embodiments, the design (for example, thickness, height, width and/or lateral and/or vertical relation to other structures in chamber150) of mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) incorporates therein suchadditional material154b′ and the fabrication of mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) to provide a final structure includes at least two steps. A first step which fabricates mechanical structures (e.g.,electrodes19,20,22,84,86,fuse89 andfield areas94,95,96) according to initial dimensions (for example, as described with respect toFIG. 4A) and a second step that includes the deposition, formation or growth ofmaterial154b′ as a result of deposition, formation or growth of at least one encapsulation layer, for example,second encapsulation layer154band/or subsequent encapsulation layer.
• With reference toFIG. 9B, in some embodiments, one or more of the encapsulation layer(s)154 are formed using one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. For the sake of brevity, the inventions described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication, will not be repeated. It is expressly noted, however, that the entire contents of the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the embodiments and/or inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• It should be understood thattransducer16 is not limited to the embodiments described above. As stated above, thetransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof.
• FIG. 10A illustrates anenergy harvesting device325 that employs thetransducer16 of micromachinedmechanical structure12, in conjunction with one or more other circuits and/ordevices326 that may be coupled thereto, in accordance with certain aspects of the present invention.
• In operation,vibrational energy328 is supplied to thetransducer16 of theenergy harvesting device325, which converts at least a portion of such energy to electrical energy. One or more portions of such electrical energy may be supplied, directly and/or indirectly, to the one or more other circuits and/ordevices326 and/or may be used, directly and/or indirectly, in powering one or more portions of the one or more other circuits and/ordevices326. For example, one or more of the voltages and/or currents generated by thetransducer16 of theenergy harvesting device325 may be supplied, directly or indirectly, to one or more circuits and/ordevices326, and/or used, directly and/or indirectly, in powering one or more portions of one or more circuits and/ordevices326.
• Unless specified otherwise, the term “device” includes, for example, but is not limited to, any type of element and/or assembly. An element may have any form including, for example, but not limited to that of a mechanical element, an electrical element and/or a combination thereof. An element may stand alone or may be connected to and/or integrated with other elements. For example, an electrical element may be a portion of an integrated circuit and electrically connected to on or more other electrical elements within the integrated circuit. An electrical element may be any type of electrical element including, for example, but not limited to a passive electrical element, an active electrical element and/or an integrated combination thereof in the form of a die that includes one or more integrated circuits. Passive electrical elements include but are not limited to any type of resistor, capacitor, inductor or combination thereof. Active electrical elements include but are not limited to any type of diode, transistor or circuit that includes one or more diodes or transistors. An assembly may also have any form including, for example, but not limited to an assembly that includes one or more mechanical elements, one or more electrical elements and/or any combination thereof. Thus, an assembly may comprise a plurality of electrical elements electrically connected to form one or more circuits. As used herein, the term circuit includes but is not limited to an integrated circuit, a discrete circuit made up of discrete devices and/or any combination thereof. A circuit may include but is not limited passive electrical elements, active electrical elements, other circuits and/or a combination thereof.
• FIG. 10B illustrates theenergy harvesting device325 in conjunction with acharge storage circuit332 and one or more other circuits and/ordevices330 that may be coupled thereto, in accordance with certain aspects of the present invention. In this embodiment,charge storage circuit332 has aninput port334 and anoutput port335. Theinput port334 of thecharge storage circuit332 is coupled viasignal lines338,339 to thetransducer16. Theoutput port335 of thecharge storage circuit332 is coupled viasignal lines341,342 to the one or more other circuits and/ordevices330.
• In operation,vibrational energy328 is supplied to thetransducer16 of micromachinedmechanical structure12, which converts at least a portion of such energy to electrical energy, at least a portion of which may be supplied throughsignal lines338,339 to thecharge storage circuit332. Thecharge storage circuit332 stores one or more portions of the electrical energy supplied thereto and may supply electrical energy, directly and/or indirectly, to the one or more other circuits and/ordevices330, which may use one or more portions of the electrical energy supplied thereto for power and/or any other purpose(s).
• FIG. 10C shows one possible embodiment of thecharge storing circuit332. In this embodiment,charge storing circuit332 includes a rectifier circuit, e.g., afull wave bridge350, and one or more energy storage devices, e.g., capacitor C1. The input ofbridge350 is coupled to theinput port334 ofcharge storing circuit332. The output ofbridge350 is coupled to the one or more storage devices, e.g., capacitor C1, which is also coupled to theoutput port335 ofcharge storing circuit332.
• Thefull wave bridge350 includes four switching devices, e.g., diodes D1, D2, D3, D4. A first terminal of the first switching device, e.g., diode D1, is connected to a first terminal of the second switching device, e.g., diode D2. A second terminal of the second switching device, e.g., diode D2, is connected to a first terminal of the third switching device, e.g., diode D3. A second terminal of the first switching device, e.g., diode D1 is connected to a first terminal of the fourth switching device, diode D4. The second terminal of the fourth switching device, e.g., diode D4, is connected to the second terminal of the third switching device, e.g., diode D3.
• The operation of thecharge storing circuit332 is as follows. Electrical energy from theenergy harvesting device325 is supplied through theinput port334 to the input of the rectifier, e.g., thefull wave bridge350, which generates a rectified voltage, Vrec. For example, second and fourth switching devices, e.g., diodes D2, D4, offull wave bridge350 conduct during a time interval T1 (FIG. 10D) for which the output voltage Vout from theenergy harvesting device325 is greater than the magnitude of the voltage across the one or more energy storage devices, e.g., capacitor C1, plus the forward voltage drop across the second and fourth switching devices. During such interval, the fourth switching device, e.g., diode D4, receives current throughsignal line338 and supplies current to a first terminal of the one or more storage devices, e.g. capacitor C1, to thereby transfer charge to the one or more storage devices, e.g., capacitor C1. Current from the second terminal of the one or more storage devices, e.g., capacitor C1, is supplied to the second switching device, e.g., diode D2, which supplies current to signalline339, which returns such current to theenergy harvesting device325.
• The first and third switching devices, e.g., diodes D1, D3, conduct during a time interval T2 (FIG. 10D) for which the output voltage Vout from theenergy harvesting device325 is negative and has an absolute value greater than the magnitude of the voltage Vstore across the one or more storage devices plus the forward voltage drop across the first and third switching devices. During such interval, the third switching device, e.g., diode D3, receives current throughsignal line339 and supplies current to the first terminal of the one or more storage devices, e.g. capacitor C1, to thereby transfer charge to the one or more storage devices, e.g., capacitor C1. Current from the second terminal of the one or more storage devices, e.g., capacitor C1, is supplied to the first switching device, e.g., diode D1, which supplies current to signalline338, which returns the current to theenergy harvesting device325. The capacitor C1 may have any suitable magnitude. In some embodiments, capacitor C1 has a magnitude of 47 microfarads (uf).
• It should be understood that thecharge storing circuit332 is not limited to a circuit having a capacitor and a full wave bridge configured as described above. The charge storing circuit may include any number and type of storage device(s) in any type of configuration. If the charge storing circuit includes a rectifier, the rectifier may include any number and type of switching devices connected in any type of configuration. If the rectifier includes a bridge, the bridge may be any type of bridge for example but not limited to a full wave bridge and/or a half wave bridge.
• FIG. 10E illustrates theenergy harvesting device325 that includes thetransducer16 of micromachinedmechanical structure12 in conjunction with apower conditioning circuit360, such as for example, an AC/DC converter circuit, and one or more other circuits and/ordevices330 that may be coupled thereto, in accordance with certain aspects of the present invention. In this embodiment,power conditioning circuit360 includes acharge storage circuit332 and a regulator, e.g., a DC/DC converter circuit362. Thecharge storage circuit332 has aninput port334 and anoutput port335. The DC/DC converter circuit362 has aninput port364 and anoutput port366. Theinput port334 of thecharge storage circuit332 is coupled viasignal lines338,339 to theenergy harvesting device325. Theoutput port335 of thecharge storage circuit332 is coupled viasignal lines341,342 to theinput port364 of the DC/DC converter circuit362. Theoutput port366 of the DC/DC converter circuit362 is coupled viasignal lines368,370 to one or more other circuits and/ordevices330.
• In operation,vibrational energy328 is supplied to theenergy harvesting device325 of micromachinedmechanical structure12, which converts at least a portion of such energy to electrical energy, at least a portion of which may be supplied throughsignal lines338,339 to thecharge storing circuit332. Thecharge storing circuit332 stores at least a portion of the electrical energy supplied thereto and generates a voltage, Vstore, which is supplied onsignal lines341,342 to the DC/DC converter circuit362. The DC/DC converter circuit362 generates a regulated DC voltage, Vreg, which may be supplied, directly or indirectly, to the one or more other circuits and/ordevices330 and/or may be used, directly and/or indirectly, in powering one or more portions of one or more circuits and/or devices and/or for any other purpose(s).
• With reference toFIG. 10F, in some embodiments, the one or more other circuits and/ordevices330 includes atransducer384 and one or more circuits and/ordevices385 coupled thereto. In such embodiments, one or more portions of the electrical energy generated by theenergy harvesting device325 may be supplied, directly and/or indirectly, to thetransducer384 and/or the one or more circuits and/ordevices385 and/or used, directly and/or indirectly, to power one or more portions of thetransducer384 and/or one or more portions of the one or more circuits and/ordevices385. For example, the regulated DC voltage, Vreg, (and/or or one or more other portions of the electrical energy generated by energy harvesting device325) may be supplied, directly and/or indirectly, to thetransducer384 and/or the one or more circuits and/ordevices385 and may be used, directly and/or indirectly, in powering one or more portions of thetransducer384 and/or one or more portions of the one or more circuits and/ordevices385.
• Thetransducer384 may be any type of transducer including, for example, but not limited to a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor). In some embodiments, thetransducer384 comprises a transducer defined by micromachinedmechanical structure12 and/or disposed in or on, and/or integrated in or on,MEMS10. In some embodiments, thetransducer384 is disposed in or on, and/or integrated in or on, thesame MEMS10 as the micromachinedmechanical structure12 definingtransducer16 ofenergy harvesting device325. In some embodiments, transducer comprises atransducer16 having electrical charge stored thereon in accordance with certain aspects of the present invention. For example, electrical charge may be stored on an electrode (see for example, first electrode19 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)). In some such embodiments, thetransducer16 may be able to operate and/or supply one or more of the one or more signals without a battery and/or an external power supply.
• In some embodiments, the one or more circuits and/ordevices385 includedata processing electronics386 and/orinterface circuitry388. In such embodiments, the regulated DC voltage, Vreg, may be supplied, directly or indirectly, to thedata processing electronics386 and/or theinterface circuitry388 and may be used, directly and/or indirectly, in powering one or more portions of one or more ofsuch circuits386,388 and/or for any other purpose(s). One or more portions of the one or more circuits may be disposed in or onMEMS10, integrated in or onMEMS10, and/or disposed in any other location.
• Thetransducer384 may be coupled to thedata processing electronics386 and/or theinterface circuitry388, for example, via one or more signal lines, e.g.,signal line389. In operation,transducer384 may generate a signal indicative of a physical quantity (e.g., vibration) sensed by thetransducer384, which may be supplied to thedata processing electronics386 and/or theinterface circuitry388, for example, via the one or more signal lines, e.g.,signal line389. In some embodiments, for example, the signal from thetransducer384 may be supplied todata processing electronics368, which may generate a signal in response at least thereto. The signal from thedata processing electronics368 may be supplied to theinterface circuitry388, which may generate a signal, in response thereto, e.g., to be provided via alink392 to other circuits and/ordevices393, further described below.
• In some embodiments, thetransducer384 and/or the one or more circuits and/ordevices385 are powered entirely by one or more portions of the electrical power generated by theenergy harvesting device325, such thattransducer384, one or more circuits and/ordevices385 and/or adevice employing transducer384 and/or one or more circuits and/ordevices385 are able to operate and/or supply information indefinitely (or at least a desired period of time) without any need for a battery and/or an external power supply.
• Data processing electronics386 may be any type of data processing electronics including, for example, but not limited to data processing electronics to (1) process and/or analyze information generated bytransducer384, micromachinedmechanical structure12 and/or any other circuits and/or devices and/or (2) control and/or monitor the operation oftransducer384, micromachinedmechanical structure12 and/or any other circuits and/or devices. Notably, information may be in any form, including, for example, but not limited to, analog and/or digital (a sequence of binary values, i.e. a bit string). Data processing circuitry may comprise a processor. As further discussed below with respect toFIG. 12H, a processor may be any type of processor.
• Interface circuitry388 may be any type of interface circuitry, including for example, but not limited to interface circuitry to (1) provide information fromtransducer384, micromachinedmechanical structure12,data processing electronics386 and/or any other circuits and/or devices to one or more external devices (FIGS. 12C-12D), for example, a computer, indicator/display and/or a sensor and/or (2) provide information totransducer384, micromachinedmechanical structure12,data processing electronics386 and/or any other circuits and/or devices from one or more external devices (FIGS. 12C-12D), for example, a computer, indicator/display and/or a sensor. As further described hereinafter,interface circuitry388 may be a portion of a communication system and/or a communication link.
• Some embodiments employ thetransducer384 without the one or more circuits and/or devices385 (see, for example, microphone900 (FIG. 57B) including transducer16 (FIG. 57B). Some other embodiments employ the one or more circuits and/ordevices385 without thetransducer384.
• With reference toFIG. 10G, in one embodiment, DC/DC converter circuit362 comprises a circuit disclosed in Knut Graichen, Ph. D. Thesis, Universitat Stuttgart, Institut for Systemdynamik and Regelungstechnik (ISR), Parasitic Power Harvesting for Automotive Tire Sensors, 2002 (hereinafter, the “Parasitic Power Harvesting for Automotive Tire Sensors” paper). It is expressly noted, that the entire contents of the Parasitic Power Harvesting for Automotive Tire Sensors paper are incorporated by reference herein, however, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited in any way by the description and/or illustrations set forth in such paper.
• In such embodiment of DC/DC converter circuit362, theinput port364 receives an input voltage, Vstore, from thecharge storing circuit332. A transistor Q1 conducts if the magnitude of the input voltage exceeds a first voltage magnitude equal to a forward voltage drop across the base emitter junction of transistor Q1 plus a voltage drop across zener diode D2. The conduction by transistor Q1 latches transistor Q1 in the conduction state and causes transistor Q2 to conduct, thereby creating a return path (i.e., a return path through resistor R1, and transistors Q1, Q2) through which the one or more energy storage devices, e.g., capacitor C1, of thecharge storing circuit332 discharges. In some embodiments, transistors Q1 and Q2 are a 2N3906 type transistor and a VN2222L type transistor, respectively. Zener diode D2 may be, for example, a 12 volt zener diode.
• The magnitudes of resistors R1, R2 and R3 are selected to provide a desired biasing for transistors Q1, Q2 and to provide a high impedance across theinput port364 of the DC/DC converter circuit while the transistors Q1, Q2 are not conducting. In one embodiment, the magnitudes of R1, R2, R3, R4 and R5 are 560 k.OMEGA., 1 M.OMEGA., 10 k.OMEGA., 820 k.OMEGA. and 100 k.OMEGA., respectively.
• This embodiment of DC/DC converter circuit362 includes a linear regulator Ul, for example, a MAX666 low power linear regulator manufactured by MAXIM, which has an input terminal Vin and an output terminal Vout. The input terminal Vin is coupled to theinput port364 through zener diode D3. The zener diode D3 has the effect of reducing leakage current when the input voltage supplied to theinput port364 reaches the first magnitude. In one embodiment, zener diode D3 is a 2.7 volt zener diode. The output terminal supplies a regulated output voltage, Vreg. In one embodiment, Vreg has a magnitude of 3 volts. The magnitude of the output voltage Vreg is determined by the magnitude of resistors Rset1 and Rset2, for example, 560 k.OMEGA. and 820 k.OMEGA., respectively, for an output voltage of 3 volts. If the magnitude of the voltage at the input terminal Vin falls below a second voltage magnitude, e.g., 2.6 volts, then a voltage at a terminal LBin (“low-battery-in”) is pulled low by the linear regulator and the voltage at a terminal LBout (“low-battery-out”) is momentarily driven to ground, thereby sending a negative pulse through capacitor C3, which causes transistor Q1 to turnoff. The turning off of transistor Q1 causes transistor Q2 to turn off, and thereby initiates a charging cycle for the one or more energy storage devices, e.g., capacitor C1, of thecharge storing circuit332. In one embodiment, resistors RLB1 and RLB2 each have a magnitude of 680 k.OMEGA. Capacitors C2, C3 and C4 may have any suitable magnitude, for example, 0.1 microfarads (uf). In some embodiments, one or more portions of the circuits and/or devices326 (e.g., charge supplyingcircuit332, DC/DC converter circuit362 and/or circuits and/or devices330) are disposed in or on, and/or integrated in or on,MEMS10.
• It should be understood that thepower conditioning circuitry360 and the DC/DC converter circuit362 are not limited to the circuits described above. Some embodiments may employ a power conditioning circuit similar to that disclosed in J. Kymissis, C. Kendall, J. Paradiso, and N. Gershenfeld, “Parasitic Power Harvesting in Shoes”, In Proc. of the Second IEEE International Conference on Wearable Computing (ISWC), IEEE Computer Society Press, October 1998, pages pp. 132-139, also published as, J. Kymissis, C. Kendall, J. Paradiso and N. Gershenfeld, “Parasitic Power Harvesting in Shoes”, Proceedings of the Second International Symposium on Wearable Computers, October 1998, pp. 132-139 (hereinafter, the “Parasitic Power Harvesting in Shoes” paper). It is expressly noted, that the entire contents of the Parasitic Power Harvesting in Shoes paper are incorporated by reference herein, however, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited in any way by the description and/or illustrations set forth in such paper.
• With reference toFIG. 10H, in one exemplary embodiment,MEMS10 includes the micromachinedmechanical structure12 disposed onsubstrate14, for example, an undoped semiconductor-like material, a glass-like material, or an insulator-like material and further includes one or more portions of one or more other circuits and/or devices326 (e.g., charge supplyingcircuit332, DC/DC converter circuit362 and/or one or more other circuits and/or devices330) that are disposed in or on, and/or integrated in or on,MEMS10 and which may be coupled, directly and/or indirectly, to the micromachinedmechanical structure12.
• As stated above, one or more portions of the electrical energy generated by theenergy harvesting device325 may be supplied, directly and/or indirectly, to the one or more circuits and/ordevices326 and/or may be used, directly and/or indirectly, in powering one or more portions of the circuits and/ordevices326 and/or for any other purpose(s). TheMEMS10 may be a monolithic structure includingmechanical structure12 and one or more portions (i.e., one, some or all portions) of the one or more other circuits and/ordevices326. In some embodiments,MEMS10 is a monolithic structure that includesmechanical structure12 and all portions of the one or more other circuits and/ordevices326. In some other embodiments, the one or more other circuits and/ordevices326 include one or more discrete devices and/or one or more portions that reside on a separate, discrete substrate that, after fabrication, is mounted on and/or bonded to or on substrate14 (or any other portion of MEMS10).
• For example, with reference toFIGS. 10I and 10J, one or moreintegrated circuits382 of the one or moreother circuits326 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent. In this regard, after fabrication and encapsulation ofmechanical structure12,integrated circuits382 may be fabricated using conventional techniques and interconnected, for example, to one or more contact areas, e.g., one or more ofcontact areas84a,86a,20a,22a, of one or more mechanical structures, e.g.,electrodes84,86,20,22, respectively, of micromachinedmechanical structure12 by way ofconductive layer192. In particular, as is also illustrated and described in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication (for example,FIGS. 12A-12C thereof) and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent (for example,FIGS. 14A-14E thereof), a contact area (e.g., one or more ofcontact areas84a,86a,20a,22a) of a mechanical structure (one or more ofelectrodes84,86,20,22, respectively) may be accessed directly byintegrated circuitry382 via a low resistance electrical path (e.g., conductive layer192) that facilitates a good electrical connection. An insulation layer (e.g., insulation layer190) may be deposited, formed and/or grown and patterned and, thereafter, a conductive layer (e.g., a conductive layer192) (for example, a heavily doped polysilicon or metal such as aluminum, chromium, gold, silver, molybdenum, platinum, palladium, tungsten, titanium, and/or copper) may be formed.
• With reference toFIG. 10K, in some embodiments the other circuits and/ordevices326 includescharge storage circuit332 and one or more other circuits and/ordevices330 disposed in or on, and/or integrated in or on,MEMS10. As stated above, in operation,vibrational energy328 may be supplied to theenergy harvesting device325, which may convert at least a portion of such energy to electrical energy, one or more portions of which may be supplied to thecharge storage circuit332. Thecharge storage circuit332 may store one or more portions of the electrical energy supplied thereto and may supply electrical energy, directly and/or indirectly, to the one or more other circuits and/ordevices330, which may use one or more portions of the electrical energy supplied thereto for power and/or any other purpose(s).
• With reference toFIG. 10L, in some embodiments the other circuits and/ordevices326 includescharge storage circuit332, DC/DC converter circuit362 and one or more other circuits and/ordevices330 disposed in or on, and/or integrated in or on,MEMS10. As stated above, in operation,vibrational energy328 may be supplied to theenergy harvesting device325, which may convert at least a portion of such energy to electrical energy, one or more portions of which may be supplied to thecharge storing circuit332. Thecharge storing circuit332 stores at least a portion of the electrical energy supplied thereto and generates a voltage, Vstore, which may be supplied to the DC/DC converter circuit362. The DC/DC converter circuit362 may generate a regulated DC voltage, Vreg, which may be supplied, directly or indirectly, to the one or more other circuits and/ordevices330 and/or may be used, directly and/or indirectly, in powering one or more portions of one or more circuits and/or devices and/or for any other purpose(s).
• With reference toFIG. 11, in some embodiments, the one or more circuits and/ordevices326 includesdata processing electronics386 and/orinterface circuitry388 disposed in or on, and/or integrated in or on,MEMS10. In one exemplary embodiment,MEMS10 includes the micromachinedmechanical structure12 disposed onsubstrate14, for example, an undoped semiconductor-like material, a glass-like material, or an insulator-like material and further includesdata processing electronics386 andinterface circuitry388 disposed in or on, and/or integrated in or on,MEMS10. As stated above,data processing electronics386 may be any type of data processing electronics including, for example, but not limited to data processing electronics to (1) process and/or analyze information generated bytransducer384, micromachinedmechanical structure12 and/or any other circuits and/or devices, and/or (2) control and/or monitor the operation oftransducer384, micromachinedmechanical structure12 and/or any other circuits and/or devices. As stated above, data processing circuitry may comprise a processor.Interface circuitry388 may be any type of interface circuitry including, for example, but not limited to interface circuitry to (1) provide information from a transducer, micromachinedmechanical structure12,data processing electronics386, and/or any other circuits and/or devices to one or more external devices (FIGS. 12C-12D), for example, a computer, indicator/display and/or sensor and/or (2) provide information to a transducer, micromachinedmechanical structure12,data processing electronics386 and/or any other circuits and/or devices from one or more external devices (FIGS. 12C-12D), for example, a computer, indicator/display and/or a sensor.
• Thedata processing electronics386 and/orinterface circuitry388 may be integrated in or onsubstrate14. In this regard,MEMS10 may be a monolithic structure includingmechanical structure12,data processing electronics386 andinterface circuitry388. One or more portions ofdata processing electronics386 and/orinterface circuitry388 may also reside on a separate, discrete substrate that, after fabrication, is bonded to or onsubstrate14.
• For example, with reference toFIGS. 12A and 12B,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent (see, for example,FIG. 13B). In this regard, after fabrication and encapsulation ofmechanical structure12,integrated circuits390 may be fabricated using conventional techniques and interconnected, for example, to one or more contact areas, e.g., one or more ofcontact areas84a,86a,20a,22a, of one or more mechanical structures, e.g.,electrodes84,86,20,22, respectively, of micromachinedmechanical structure12 by way ofconductive layer192. In particular, as is also illustrated and described in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication (for example,FIGS. 12A-12C thereof and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent (for example,FIGS. 14A-14E thereof), a contact area (e.g., one or more ofcontact areas84a,86a,20a,22a) of a mechanical structure (one or more ofelectrodes84,86,20,22, respectively) may be accessed directly byintegrated circuitry390 via a low resistance electrical path (e.g., conductive layer192) that facilitates a good electrical connection. An insulation layer (e.g., insulation layer190) may be deposited, formed and/or grown and patterned and, thereafter, a conductive layer (e.g., a conductive layer192) (for example, a heavily doped polysilicon or metal such as aluminum, chromium, gold, silver, molybdenum, platinum, palladium, tungsten, titanium, and/or copper) may be formed.
• As stated above, one or more portions ofdata processing electronics386 and/or one or more portions ofinterface circuitry388 may receive, directly and/or indirectly, electrical energy generated by theenergy harvesting device325. The electrical energy may be used, directly and/or indirectly, in powering one or more portions of thedata processing electronics386 andinterface circuitry388 and/or for any other purpose(s).
• With reference toFIG. 12C, in some embodiments,interface circuitry388 may be coupled to, and/or a portion of, one or more communication links, e.g.,communication link392, to one or more circuits and/ordevices393, disposed external toMEMS10. A communication link may be any kind of communication link including, for example, but not limited to, for example, wired (e.g., conductors, fiber optic cables) or wireless (e.g., acoustic links, electromagnetic links or any combination thereof including, for example, but not limited to microwave links, satellite links, infrared links), and combinations thereof, each of which may be public or private, dedicated and/or shared (e.g., a network). A communication link may transmit any type of information in any form, including, for example, but not limited to, analog and/or digital (a sequence of binary values, i.e. a bit string). The information may or may not be divided into blocks. If divided into blocks, the amount of information in a block may be predetermined or determined dynamically, and/or may be fixed (e.g., uniform) or variable. A communication link may employ a protocol or combination of protocols including, for example, but not limited to the Internet Protocol.
• Accordingly,interface circuitry388 may include one or more circuits for use in association with one or more wired communication links, one or more circuits for use in association with one or more wireless communication links and/or any combination thereof. In some embodiments,interface circuitry388 includes circuitry to facilitate wired, wireless and/or optical communication to and/or fromMEMS10 and/or withinMEMS10. The circuitry to facilitate wired, wireless and/or optical communication may have any form. In some embodiments, one or more portions of the circuitry to facilitate wired, wireless and/or optical communication is disposed in the same integrated circuit as one or more other portions of theinterface circuitry388 and/ordata processing electronics386. In some embodiments, one or more portions of the circuitry to facilitate wired, wireless and/or optical communication may be disposed in or on, and/or integrated in or on,MEMS10. In some embodiments, one or more portions of the circuitry to facilitate wired, wireless and/or optical communication is in a discrete form, separate from the other portions of theinterface circuitry388 and/ordata processing electronics386.
• With reference toFIG. 12D, in some embodiments, the one or more circuits and/ordevices326 includescharge storage circuit332, DC/DC converter circuit362,data processing electronics386 andinterface circuitry388 disposed in or on, and/or integrated in or on,MEMS10. In one exemplary embodiment,MEMS10 includes the micromachinedmechanical structure12 disposed onsubstrate14, for example, an undoped semiconductor-like material, a glass-like material, or an insulator-like material and further includes one or more other circuits and ordevices326, includingcharge storage circuit332, DC/DC converter circuit362,data processing electronics386 andinterface circuitry388 disposed in or on, and/or integrated in or on,MEMS10. One or more portions of the electrical energy generated by theenergy harvesting device325 may be supplied, directly and/or indirectly, to one or more portions of thedata processing electronics386 and/or one or more portions of theinterface circuitry388. Such electrical energy may be used in powering one or more portions of thedata processing electronics386, powering one or more portions of theinterface circuitry388 and/or for any other purpose(s).
• It should be understood that a circuit and/or device may include, for example, hardware, software, firmware, hardwired circuits and/or any combination thereof. Moreover, a circuit and/or device may be, for example, programmable or non programmable, general purpose or special purpose, dedicated or non dedicated, distributed or non distributed, shared or not shared, and/or any combination thereof. If a circuit and/or device is a distributed circuit and/or device, two or more portions of such circuit and/or device may be coupled to one another in any way, for example, but not limited by via electrical conductors, and/or may communicate with one another via one or more communication links.
• In some embodiments, one ormore MEMS10 are employed in one or more devices employed in a distributed system.
• With reference toFIG. 12E, in one embodiment, a distributedsystem394 includes one or more devices, e.g.,devices395a,395b, connected via acommunication system396 to one or more circuits and/or devices, e.g., ahost receiver393 and/or processor. Thecommunication system396 may be any type of communication system and may include one or more communication links, e.g.,communication links392a,392b. The communication system may be used, for example, in providing information from one or more of the devices to the host receiver and/orprocessor393 and/or in providing information from the host receiver and/orprocessor393 to one or more of the devices. The information may have any form, including for example, but not limited to, data type information and/or control type information. Thehost receiver393 may include any type of receiver and/or processor. As further discussed below with respect toFIG. 12H, a processor may be any type of processor.
• Each of the one or more devices, e.g.,devices395a,395b, may be any type of device including, but not limited to, an energy harvesting device, a sensor (e.g., an accelerometer, gyroscope, microphone, pressure sensor, strain sensor, tactile sensor, magnetic sensor and/or temperature sensor), a resonator, a resonant filter, a processor, an input device, and output device and/or any combination thereof.
• In some embodiments, one or more of the one or more devices, e.g.,devices395a,395b, includes one or more of theMEMS10 described herein. As stated above,MEMS10 may be any type of device including, for example, but not limited to, an energy harvesting device, a sensor (e.g., an accelerometer, gyroscope, microphone, pressure sensor, strain sensor, tactile sensor, magnetic sensor and/or temperature sensor), a resonator, a resonant filter, a processor, an input device, and output device and/or any combination thereof.
• One or more of the one ormore MEMS10 may include anenergy harvesting device325. As described above, energy (e.g., vibrational energy) may be supplied to theenergy harvesting device325, which may convert at least a portion of such energy to electrical energy.
• With reference toFIG. 12J, in some embodiments, one or more of the devices, e.g.,devices395a,395b, further includes one or more other circuits and/or devices, e.g., other circuits and/ordevices326. One or more portions of the electrical energy generated by theenergy harvesting device325 may be supplied, directly and/or indirectly, to the one or more other circuits and/ordevices326 and/or may be used, directly and/or indirectly, in powering one or more portions of the one or more other circuits and/ordevices326 and/or for any other purpose(s). Such one or more other circuits and/ordevices326 may be disposed in or onMEMS10, integrated in or onMEMS10, and/or disposed in any other location. In some embodiments, one, some or all of the devices, e.g.,devices395a,395b, are powered entirely by one or more portions of the electrical energy generated by theenergy harvesting device325 such that one, some or all of such devices e.g.,devices395a,395b, are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• In some embodiments, the one or more other circuits ordevices326 includes apower conditioning circuit360, atransducer384 and one or more other circuits and/ordevices385 coupled thereto. Thepower conditioning circuit360 may receive one or more portions of the electrical energy generated by theenergy harvesting device325 and may generate a regulated voltage from such energy. The regulated voltage may be supplied, directly and/or indirectly, to thetransducer384 and/or the one or more circuits and/ordevices385 and may be used, directly and/or indirectly, in powering one or more portions of thetransducer384 and/or one or more portions of the one or more circuits and/ordevices385 or for any other purpose.
• As stated above, thetransducer384 may be any type of transducer including, for example, but not limited to a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor). In some embodiments,transducer384 comprises atransducer16 having electrical charge stored on one or more portions thereof in accordance with one or more aspects of the present invention. For example, electrical charge may be stored on an electrode (see for example, first electrode19 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)). In some such embodiments, thetransducer16 may be able to operate and/or supply one or more of the one or more signals without power fromenergy harvesting device325, a battery and/or an external power supply. In some embodiments, thetransducer384 is disposed in or on, and/or integrated in or on, thesame MEMS10 as the micromachinedmechanical structure12 definingtransducer16 ofenergy harvesting device325.
• In some embodiments, the one or more circuits and/ordevices385 includedata processing electronics386 and/orinterface circuitry388. The regulated voltage from thepower conditioning circuit360 may be supplied, directly and/or indirectly, to thedata processing electronics386 and/or theinterface circuitry388 and may be used, directly and/or indirectly, in powering one or more portions of one or more of such circuits and/or for any other purpose(s). One or more portions of the one or more circuits and/ordevices385 may be disposed in or onMEMS10, integrated in or onMEMS10, and/or disposed in any other location.
• Thetransducer384 may be coupled to thedata processing electronics386 and/or theinterface circuitry388, for example, via one or more signal lines, e.g.,signal line389. In operation,transducer384 may generate a signal indicative of a physical quantity (e.g., vibration) sensed by thetransducer384, which may be supplied to thedata processing electronics386 and/or theinterface circuitry388, for example, via the one or more signal lines, e.g.,signal line389. In some embodiments, the signal from thetransducer384 may be supplied todata processing electronics368, which may generate a signal in response at least thereto. The signal from thedata processing electronics368 may be supplied to theinterface circuitry388, which may generate a signal in response thereto.Interface circuitry388 may interface to, and/or may be a portion of,communication link392, which may supply the signal from theinterface circuitry388 to thehost receiver393. Some embodiments employ thetransducer384 without the one or more circuits and/ordevices385. Some other embodiments employ the one or more circuits and/ordevices385 without thetransducer384.
• In some embodiments,transducer384 and/or one or more circuits and/ordevices385 are powered entirely by one or more portions of the electrical power generated by theenergy harvesting device325, such thattransducer384, one or more circuits and/ordevices385 and/or adevice employing transducer384 and/or one or more circuits and/ordevices385 are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• In some embodiments, one or more of the devices, e.g.,devices395a,395b, include atransducer384 that comprises a transducer for monitoring one or more characteristics of a tire (e.g., an automotive tire sensor), a transducer for use in monitoring one or more industrial processes, a transducer for use in monitoring one or more environmental conditions (e.g., a weather condition), and/or a transducer for use in monitoring one or more activities relating to security (e.g., homeland security).
• With reference also toFIG. 12F, in one such embodiment, each of the plurality of devices, e.g.,devices395a,395b, comprises one ormore MEMS10 and one ormore transducers384 that include one or more transducers to monitor tire conditions, e.g., temperature, pressure and/or vibration.MEMS10 may include aenergy harvesting device325. The devices, e.g.,devices395a,395b, are spaced apart from one another (e.g., on the tire of the vehicle). The transducer(s) monitor one or more tire conditions (e.g., temperature, pressure and/or vibration) and generate one or more signals indicative of the temperature, pressure and/or vibration thereof. In some embodiments, one or more of the signals are supplied to data processing electronics and/orinterface circuitry388, which supplies information indicative thereof, to thehost receiver393.Host receiver393 may be disposed on the vehicle or at any other location. If an energy harvesting device325 (e.g., a vibrational energy to electrical energy converter) is employed,energy harvesting device325 is exposed to vibrational energy (or another type of energy) and generates electrical energy in response thereto. One or more portion of the electrical energy is used, directly and/or indirectly, to power one or more of the transducer(s) and/orinterface circuitry388. In some embodiments, one or more of the transducer(s) to monitor tire conditions (e.g., temperature, pressure and/or vibration) andinterface circuitry388 are disposed in or on and/or integrated in or onMEMS10. In some embodiments, one, some or all of the devices, e.g.,devices395a,395b, are powered entirely byenergy harvesting device325 such that one, some or all of such devices e.g.,devices395a,395b, are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• With reference also toFIG. 12G, in another embodiment, each of the plurality of devices, e.g.,devices395a,395b, comprises one ormore MEMS10 and one ormore transducers384 that include one or more transducers for monitoring an industrial process.MEMS10 may include aenergy harvesting device325. The devices, e.g.,devices395a,395b, are spaced apart from one another (e.g., within the industrial facility). The transducer(s) monitors the industrial process and generate one or more signals indicative of the process conditions being monitored. In some embodiments, one or more of the signals are supplied to data processing electronics and/orinterface circuitry388, which supplies information indicative thereof, to thehost receiver393.Host receiver393 may be disposed at a remote location within the industrial facility. If an energy harvesting device325 (e.g., a vibrational energy to electrical energy converter) is employed,energy harvesting device325 is exposed to vibrational energy (or other type of energy) and generates electrical energy in response thereto. One or more portion of the electrical energy is used, directly and/or indirectly, to power one or more of the transducer(s) and/orinterface circuitry388. In some embodiments, one or more of the transducer(s) andinterface circuitry388 are disposed in or on and/or integrated in or onMEMS10. In some embodiments, one, some or all of the devices, e.g.,devices395a,395b, are powered entirely byenergy harvesting device325 such that one, some or all of such devices e.g.,devices395a,395b, are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• With reference also toFIG. 12H, in another embodiment, each of the plurality of devices, e.g.,devices395a,395b, comprises one ormore MEMS10 and one ormore transducers384 that include one or more transducers for use in monitoring one or more environmental conditions (e.g., temperature, pressure, vibration).MEMS10 may include aenergy harvesting device325. The devices, e.g.,devices395a,395b, are spaced apart from one another (e.g., outdoors). The transducer(s) monitor one or more environmental conditions and generate one or more signals indicative of the environmental condition(s) being monitored (e.g., temperature, pressure, vibration). In some embodiments, one or more of the signals are supplied to data processing electronics and/orinterface circuitry388, which supplies information indicative thereof, to thehost receiver393. Host receiver may be disposed at a remote location (e.g., a weather center). If an energy harvesting device325 (e.g., a vibrational energy to electrical energy converter) is employed,energy harvesting device325 is exposed to vibrational energy (or other type of energy) and generates electrical energy in response thereto. One or more portion of the electrical energy is used, directly and/or indirectly, to power one or more of the transducer(s) and/orinterface circuitry388. In some embodiments, one or more of the transducer(s) andinterface circuitry388 are disposed in or on and/or integrated in or onMEMS10. In some embodiments, one, some or all of the devices, e.g.,devices395a,395b, are powered entirely byenergy harvesting device325 such that one, some or all of such devices e.g.,devices395a,395b, are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• With reference also toFIG. 12I, in another embodiment, each of the plurality of devices, e.g.,devices395a,395b, comprises one ormore MEMS10 and one ormore transducers384 that include one or more transducers for use in monitoring one or more conditions and/or activities relating to security (e.g., homeland security).MEMS10 may include aenergy harvesting device325. The devices, e.g.,devices395a,395b, are spaced apart from one another (e.g., at a location to be monitored). The transducer(s) monitor one or more conditions and/or activities relating to security and generate one or more signals indicative of the conditions and/or activities being monitored. In some embodiments, one or more of the signals are supplied to data processing electronics and/orinterface circuitry388, which supplies information indicative thereof, to thehost receiver393.Host receiver393 may be disposed at a remote location (e.g., a local monitoring station). If an energy harvesting device325 (e.g., a vibrational energy to electrical energy converter) is employed,energy harvesting device325 is exposed to vibrational energy (or other type of energy) and generates electrical energy in response thereto. One or more portion of the electrical energy is used, directly and/or indirectly, to power one or more of the transducer(s) and/orinterface circuitry388. In some embodiments, one or more of the transducer(s) andinterface circuitry388 are disposed in or on and/or integrated in or onMEMS10. In some embodiments, one, some or all of the devices, e.g.,devices395a,395b, are powered entirely byenergy harvesting device325 such that one, some or all of such devices e.g.,devices395a,395b, are able to operate and/or supply information indefinitely (or at least a desired period of time), without any need for a battery and/or an external power supply.
• Some embodiments may employ one or more of the methods and/or devices described and/or illustrated in (1) the “Parasitic Power Harvesting in Shoes” paper and/or (2) the “Parasitic Power Harvesting for Automotive Tire Sensors” paper. As stated above, the entire contents of the Parasitic Power Harvesting in Shoes paper and the Parasitic Power Harvesting for Automotive Tire Sensors paper are each incorporated by reference herein, however, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited in any way by the description and/or illustrations set forth in such papers.
• The one or more devices, e.g.,devices395a,395b, may be located in one geographic location or may be distributed among two or more geographic locations. Thehost receiver393 may be located in the same geographic location as one or more of the plurality of devices, e.g.,devices395a,395b, or in a geographic location different from that of any of the plurality of devices, e.g.,devices395a,395b. As stated above, thehost receiver393 may be any type of receiver and may include a processor.
• It should also be understood that a processor may be implemented in any manner. For example, a processor may be programmable or non programmable, general purpose or special purpose, dedicated or non dedicated, distributed or non distributed, shared or not shared, and/or any combination thereof. If the processor has two or more distributed portions, the two or more portions may communicate via one or more communication links
• A processor may include, for example, but is not limited to, hardware, software, firmware, hardwired circuits and/or any combination thereof. In some embodiments, one or more portions of a processor may be implemented in the form of one or more ASICs. A processor may include, for example, but is not limited to, a computer. A processor may or may not execute one or more computer programs that have one or more subroutines, or modules, each of which may include a plurality of instructions, and may or may not perform tasks in addition to those described herein. If a computer program includes more than one module, the modules may be parts of one computer program, or may be parts of separate computer programs. As used herein, the term module is not limited to a subroutine but rather may include, for example, hardware, software, firmware, hardwired circuits and/or any combination thereof.
• In some embodiments, a processor comprises at least one processing unit connected to a memory system via an interconnection mechanism (e.g., a data bus). A memory system may include a computer-readable and writeable recording medium. The medium may or may not be non-volatile. Examples of non-volatile medium include, but are not limited to, magnetic disk, magnetic tape, non-volatile optical media and non-volatile integrated circuits (e.g., read only memory and flash memory). A disk may be removable, e.g., known as a floppy disk, or permanent, e.g., known as a hard drive. Examples of volatile memory include but are not limited to random access memory, e.g., dynamic random access memory (DRAM) or static random access memory (SRAM), which may or may not be of a type that uses one or more integrated circuits to store information.
• If a processor executes one or more computer programs, the one or more computer programs may be implemented as a computer program product tangibly embodied in a machine-readable storage medium or device for execution by a computer. Further, if a processor is a computer, such computer is not limited to a particular computer platform, particular processor, or programming language. Computer programming languages may include but are not limited to procedural programming languages, object oriented programming languages, and combinations thereof.
• A computer may or may not execute a program called an operating system, which may or may not control the execution of other computer programs and provides scheduling, debugging, input/output control, accounting, compilation, storage assignment, data management, communication control, and/or related services. A computer may for example be programmable using a computer language such as C, C++, Java or other language, such as a scripting language or even assembly language. The computer system may also be specially programmed, special purpose hardware, or an application specific integrated circuit (ASIC).
• Example output devices include, but are not limited to, displays (e.g., cathode ray tube (CRT) devices, liquid crystal displays (LCD), plasma displays and other video output devices), printers, communication devices for example modems, storage devices such as a disk or tape and audio output, and devices that produce output on light transmitting films or similar substrates. An output device may include one or more interfaces to facilitate communication with the output device. The interface may be any type of interface, e.g., proprietary or not proprietary, standard (for example, universal serial bus (USB) or micro USB) or custom or any combination thereof.
• Example input devices include but are not limited to buttons, knobs, switches, keyboards, keypads, track ball, mouse, pen and tablet, light pen, touch screens, and data input devices such as audio and video capture devices. An output device may include one or more interfaces to facilitate communication with the output device. The interface may be any type of interface, for example, but not limited to, proprietary or not proprietary, standard (for example, universal serial bus (USB) or micro USB) or custom or any combination thereof. Input signals to a processor may have any form and may be supplied from any source, for example, but not limited to.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof.
• For example, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example, micromachinedmechanical structure12 ofFIGS. 11B,11C and11D of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or micromachinedmechanical structure12 ofFIGS. 13B,13C and13D of Microelectromechanical Systems Having Trench Isolated Contacts Patent). Under such circumstance, theMEMS10 may be fabricated using the techniques described in this application wherein the mechanical structures include one or more processing steps to provide the vertically and/or laterally stacked and/or interconnected multiple layers (see, for example,FIGS. 13A and 13B).
• Thus, any of the techniques, materials and/or embodiments of fabricating and/or encapsulating micromachinedmechanical structure12 that are described in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or in the Microelectromechanical Systems Having Trench Isolated Contacts Patent may be employed with the embodiments and/or the inventions described herein.
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent).
• In this regard, with reference toFIGS. 13A and 13B, in one embodiment, anchors397 and/or398 may be comprised of a material that is relatively unaffected by the release processes of the mechanical structures. In this regard, the etch release process are selective or preferential to the material(s) securingmechanical structures16 in relation to the material comprising anchors397. Moreover, anchors397 and/or398 may be secured tosubstrate14 in such a manner that removal ofinsulation layer190 has little to no affect on the anchoring ofmechanical structures16 tosubstrate14.
• It should be noted that the embodiments described herein may be incorporated intoMEMS10 described and illustrated in Anchors for Microelectromechanical Systems Patent. For the sake of brevity, the inventions and/or embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent will not be repeated. It is expressly noted, however, that the entire contents of the Anchors for Microelectromechanical Systems Patent, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the embodiments and/or inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• The fabrication and/or formation of the structures of micromachinedmechanical structure12 may be accomplished using the techniques described and illustrated herein or any conventional technique. Indeed, all techniques and materials used to fabricate and/or formmechanical structure12, whether now known or later developed, are intended to be within the scope of the present invention.
• FIGS. 14A-14B andFIGS. 15A-15B illustrate plan views and cross sectional views, respectively, of a portion of another micromachinedmechanical structure12 that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated inFIGS. 14A-14B andFIGS. 15A-15B includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however, thetransducer12 is not limited to such.
• In the micromachinedmechanical structure12 illustrated inFIGS. 14A-14B andFIGS. 15A-15B,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example first, second andthird electrodes19,20,22. The first, second andthird electrodes19,20,22 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, for example, thefirst electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. The movablemechanical structure28 is similar to the movablemechanical structure28 of thefirst electrode19 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E. The second andthird electrodes20,22 comprise fixed mechanical structures with generally rectangular shapes similar to that of the second andthird electrodes20,22 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). In this embodiment, the one or moremechanical structures82 include afirst electrode84, asecond electrode86 and athermionic electron source400. The one or moremechanical structures82 may have any configuration (e.g., size, shape, orientation). In the illustrated embodiment, for example, the first andsecond electrodes84,86 comprise fixed mechanical structures having generally rectangular shapes spaced apart from one another by agap402. Thethermionic electron source400 includes afilament403 connected between the first andsecond electrodes84,86 and spaced apart from thefirst electrode19 of the transducer (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored) by one or more gaps, e.g., agap404.
• The one or moremechanical structures82 may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table for example silicon, germanium, carbon; and combinations thereof, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• With reference toFIG. 14B, thefilament403 may include first, second andthird portions406,408,410 arranged, for example, in a “U” shape. Thefirst portion408 may have afirst end406athat connects to thefirst electrode84 and asecond end406bthat connects to afirst end408aof thesecond portion408. Thesecond portion408 may have asecond end408bthat connects to afirst end410aof athird portion410, asecond end410bof which connects to thesecond electrode86.
• Thethermionic electron source400 may include one or more surfaces, e.g.,surface412 offilament403, that face in a direction toward, and/or are disposed in register with, one or more surfaces, e.g.,surface413, of thefirst electrode19 of the transducer16 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). In some embodiments, one or more of such surfaces, e.g., one or more ofsurfaces412413, has alength414 of at least about 200 microns and awidth416 of about 1 micron.
• One or more clearances, e.g., clearances418a-418c(FIGS. 14B,15A), may be provided between one or more portions of thethermionic electron source400 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g., clearances418a-418c, may help reduce the thermal conductivity between thethermionic electron source400 and the rest of the micromachinedmechanical structure12, thereby reducing the amount of energy needed to heat the thermionic electron source to a temperature at which electrons are emitted therefrom, as further discussed below. In some embodiments, the one or more clearances, e.g., clearances418a-418c, provide clearance around each surface of thethermionic electron source400 except at one or more ends, e.g., ends406a,410b, where thethermionic electron source400 connects to one or more structures, e.g., the first andsecond electrodes84,86, respectively, such that the thermionic electron source is suspended from such structures.
• FIG. 16 illustrates one embodiment for employing thethermionic electron source400 to facilitate supplying, storing and/or trapping of electrical charge on thefirst electrode19 of thetransducer16 illustrated inFIGS. 14A-14B andFIGS. 15A-15B (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention.
• Referring toFIG. 16, in this embodiment, first andsecond electrodes84,86 are electrically connected to a first power source, e.g., avoltage source422, that provides a first voltage potential across the first andsecond electrodes84,86. One of theelectrodes84,86 (e.g., the electrode connected to the terminal of the first power source, e.g.,voltage source422, having the lower potential) is also connected to a second power source, e.g., avoltage source423, that provides a second voltage potential to bias the first andsecond electrodes84,86 from ground.
• The first power source, e.g.,voltage source422, thereafter supplies a current424 that flows through thefirst electrode84, thethermionic electron source400 and thesecond electrode86. The electric current424 causes power dissipation and heating in one or more portions of thethermionic electron source400, e.g., thesecond portion408, such that one or more of such portions, e.g., thesecond portion408, becomes superheated and reaches or exceeds a high temperature (e.g., a temperature of about 800 degrees Centigrade) at which electrons are emitted from the surface of such portion(s).
• Some of theelectrons426 emitted by thethermionic source400 travel across thegap404 and reach the electrode19 (or other mechanical structure(s) on which charge is to be stored) and become trapped thereon. The charge stored and/or trapped on the electrode19 (or other mechanical structure(s)) may cause an increase in the voltage thereof.
• The charge supplying process may continue until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, the second power source, e.g.,voltage source423, supplies a voltage equal to the desired voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the second power source, e.g.,voltage source423, and then stops. As stated above, in some embodiments, the desired voltage is within a range of from about 100 volts to about 1000 volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded).
• The charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current424 supplied to thethermionic electron source400 may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying, direct current or alternating current, and/or any combination of the above.
• After a desired amount of charge has been supplied, it may be desirable to stop the flow of current to thethermionic electron source400, so as to stop the heating of thethermionic electron source400 and the emission of electrons therefrom. This may be accomplished, for example, by disconnecting the first andsecond electrodes84,86 from the first power source, e.g.,voltage source422. The second power source, e.g.,voltage source423, may also be disconnected from the micromachinedmechanical structure12.
• Notably, at the end of the charge supplying process employed in the embodiment ofFIG. 16, the first electrode19 (and/or any other portions of the structure on which charge is to be stored) is electrically isolated from all other electrically conductive structures inside the chamber and outside the chamber.
• In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided between thefirst electrode19 and other electrically conductive structures within the chamber including, or example, each of theother electrodes20,22 and theelectrodes84,86 temporarily connected to the power source during the charge supplying process. Such a configuration helps reduce the possibility of excessive surface leakage that could otherwise lead to excessive drain of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored.
• In addition, as stated above, at the end of the charge supplying process employed in the embodiment ofFIG. 16, the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) is also electrically isolated from electrically conductive structures outside the chamber. As stated above, structures outside the chamber may have more contamination and/or greater potential for leakage current and/or drain than structures inside the chamber. Thus, providing electrical isolation from conductive structures outside of the chamber may significantly reduce leakage current and/or drain.
• In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided, thereby reducing the possibility of excessive leakage through the one or moremechanical structures82 to points outside the chamber that could otherwise lead to excessive drain of the electrical charge on the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored).
• The efficiency of the charge supplying process may depend, at least in part, on the surface area of the one or more portions of thethermionic electron source400 that face toward the charge supplying portion and emit electrons, and the magnitude of the gap between thethermionic electron source400 and thefirst electrode19 of the transducer16 (or other mechanical structure(s)) on which charge is to be stored and/or trapped).
• One or more portions ofthermionic electron source400 may have a configuration adapted to increase the thermal resistance thereof, thereby making it easier to heat the thermionic electron source to a temperature at which the electrons are emitted therefrom. In that regard, thermionic electron source may span a major portion of the width of thechamber150. In some embodiments, thethermionic electron source400 has a total length of at least 200 microns.
• In some embodiments, a vacuum or near vacuum is provided within thechamber150. The vacuum or near vacuum may help reduce or minimize heat transfer within thechamber150 and thereby help to reduce or minimize the amount of energy needed to heat thethermionic electron source400. In some embodiments, for example, the amount of power needed to heat thethermionic electron source400 is several orders of magnitude less than the amount of power that would be required to heat thethermionic electron source400 if a vacuum or near vacuum was not provided within thechamber150.
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 17A-17J illustrate cross-sectional views an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 14A-14B andFIGS. 15A-15B, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 17A, in the exemplary embodiment, fabrication ofMEMS10 having micromachinedmechanical structure12 including a thermionic electron source may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86,thermionic electron source400 andelectrodes19,20,22, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86,thermionic electron source400 andelectrodes19,20,22, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 having the thermionic electron source may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 including thermionic electron source is illustrated inFIGS. 17B-17J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E-10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11A andFIGS. 12A-12D). For example, with reference toFIGS. 18A and 18B,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example,FIGS. 19A and 19B).
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein (see, for example,FIGS. 19A and 19B).
• FIGS. 20A-20B andFIGS. 21A-21C illustrate plan views and cross sectional views, respectively, of a portion of another micromachinedmechanical structure12 that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated inFIGS. 20A-20B andFIGS. 21A-21C includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however thetransducer12 is not limited to such.
• In the micromachinedmechanical structure12 illustrated inFIGS. 20A-20B andFIGS. 21A-21C,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example first, second andthird electrodes19,20,22. The first, second andthird electrodes19,20,22 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, for example, the first, second and third electrodes have configurations that are similar to that of the first, second andthird electrodes19,20,22, respectively, of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). In this embodiment, the one or moremechanical structures82 include afirst electrode84, asecond electrode86 and anelectron gun430. The one or moremechanical structures82 may have any configuration (e.g., size, shape, orientation). In the illustrated embodiment, for example, the first andsecond electrodes84,86 comprise fixed mechanical structures having generally rectangular shapes spaced apart from one another by agap402. Theelectron gun430 includes athermionic electron source400 and abeam shaper440. Thethermionic electron source400 may include afilament403 connected between first andsecond electrodes84,86 and spaced apart from thefirst electrode19 of the transducer (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored) by one or more gaps, e.g., agap404.
• The one or moremechanical structures82 may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table for example silicon, germanium, carbon; and combinations thereof, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• With reference toFIG. 20B, thefilament403 may include first, second andthird portions406,408,410 arranged, for example, in a “U” shape. Thefirst portion408 may have afirst end406athat connects to thefirst electrode84 and asecond end406bthat connects to afirst end408aof thesecond portion408. Thesecond portion408 may have asecond end408bthat connects to afirst end410aof athird portion410, asecond end410bof which connects to thesecond electrode86.
• Thethermionic electron source400 may include one or more surfaces, e.g.,surface412 offilament403, that face in a direction toward, and/or are disposed in register with, one or more surfaces, e.g.,surface413, of thefirst electrode19 of the transducer16 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored).
• Thebeam shaper440 may include first andsecond electrodes442,444. In the illustrated embodiment, first andsecond electrodes442,444 are fixed mechanical structures with generally “L” shapes disposed on opposite sides of, and equally spaced from, areference plane443. Each of theelectrodes442,444 has afirst portion445 and asecond portion446. Thesecond portion446 of eachelectrode442,444 extends in a direction toward thereference plane443 and in register with thesecond portion446 of theopposite electrode444,442, respectively. Thesecond portions446 are spaced apart from thethermionic electron source400 by agap450 and define anaperture452 that defines a path for electrons emitted by thethermionic electron source400 to exit theelectron gun430.
• The first andsecond electrodes442,444, may comprise any suitable material, for example, a semiconductor material (doped or undoped), for example, silicon, germanium, silicon/germanium, silicon carbide, gallium arsenide, and combinations thereof.
• The first andsecond electrodes442,444, may define one or more contact areas, e.g., contactareas442a,444a, respectively, which may provide one or more electrical paths between the micromachinedmechanical structure12 and one or more other circuits and/or devices, e.g., voltage source532 (FIG. 22).
• Referring toFIGS. 21A-21C, the micromachinedmechanical structure12 may further define one or more insulation areas, e.g.,insulation areas462,464, disposed between the substrate and theelectrodes442,444, respectively, to provide electrical isolation between thesubstrate14 and such electrodes. The one or more insulation areas, e.g.,insulation areas462,464, may comprise, for example, silicon dioxide or silicon nitride.
• The micromachinedmechanical structure12 may further define one or more insulation areas, e.g.,insulation areas472,474, disposedsuperjacent electrodes442,444, respectively, to partially, substantially or entirely surroundcontact areas442a,444aofelectrodes442,444, respectively, as may be desired. The one or more insulation areas, e.g.,insulation areas472,474, may comprise, for example, silicon dioxide or silicon nitride. One or more of the insulation areas, e.g.,insulation areas472,474, may define one or more openings, e.g.,openings482,484, respectively, to facilitate electrical contact to theelectrodes442,444, respectively.
• As stated above, the micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the entire contents which, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• The one ormore encapsulation layers154 may define one or more conductive regions, e.g.,conductive regions492,494, disposedsuperjacent electrodes442,444, respectively, to facilitate electrical contact therewith. The one ormore encapsulation layers154 may further define one or more trenches, e.g.,trenches502,504, disposed about one or more of the conductive regions, e.g.,conductive regions492,494, respectively, to electrically isolate one or more of such regions from one or more other portions of the micromachinedmechanical structure12. Insulating material may be deposited in one or more of the trenches, e.g.,trenches502,504, to form one or more isolation regions, e.g.,isolation regions512,514, respectively.
• As stated above, the micromachined mechanical structure may further define aninsulation layer190 and aconductive layer192 disposed superjacent encapsulation layer(s)154. Theinsulation layer190 may provide electrical isolation betweenconductive layer192 and one or more other portions of the micromachinedmechanical structure12, as may be desired. Theconductive layer192 may define one or more conductive regions, e.g.,conductive regions522,524 that form part of the electrical connection to one or more of the beam shaper electrodes, e.g.,electrodes442,444, respectively.
• FIG. 22 illustrates one embodiment for employing the electron gun to facilitate storing of electrical charge on thefirst electrode19 of thetransducer16 illustrated inFIGS. 20A-20B andFIGS. 21A-21C (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention.
• Referring toFIG. 22, in this embodiment, first andsecond electrodes84,86 are electrically connected to a first power source, e.g., avoltage source422, that provides a first voltage potential across the first andsecond electrodes84,86. One of theelectrodes84,86 (e.g., the electrode connected to the terminal of the first power source, e.g.,voltage source422, having the lower potential) is also connected to a second power source, e.g., avoltage source423, that provides a second voltage potential to bias the first andsecond electrodes84,86 from ground The first andsecond electrodes442,444 of thebeam shaper440 are connected to a third power source, e.g., avoltage source532, that provides a voltage potential on the first andsecond electrodes442,444 of thebeam shaper440. In some embodiments, the voltage potential provided on the first andsecond electrodes442,444 of thebeam shaper430 is greater than the voltage potential biasing the first andsecond electrodes84,86.
• The first power source, e.g.,voltage source422, supplies a current424 that flows through thefirst electrode84, thethermionic electron source400 and thesecond electrode86. The electric current424 causes one or more portions of the thermionic electron source, e.g.,second portion408, to dissipate power and produce heat that causes one or more of such portions, e.g.,second portion408, to reach or exceed a temperature at whichelectrons426 are emitted from the surface thereof. The temperature may be a relatively high temperature and may or may not be below the melting temperature of such portion(s) of thethermionic electron source400. In some embodiments, one or more portions ofthermionic electron source400, e.g., thesecond portion408 offilament403, becomes superheated and/or reaches or exceeds a temperature of about 800 degrees C. at whichtemperature electrons426 are emitted from the surface thereof. The magnitude of the power dissipation and heating may depend at least in part on the magnitude of the current and/or the voltage across thethermionic electron source400. In some embodiments, the power dissipated by thethermionic electron source150 is greater than or equal to one milliwatt (mw).
• Thebeam shaper440 causes at least some of the electrons emitted from thethermionic electron source400 to form into abeam536 as they travel toward thefirst electrode19 of the transducer16 (or other mechanical structure(s) on which charge is to be stored). The configuration (e.g., shape, charge density distribution) of the electron beam may depend, at least in part, on thegap450 between thethermionic electron source400 and thebeam shaper440, and on the difference between the voltage potential of thethermionic electron source400 and the voltage potential of thebeam shaper440.
• At least some of theelectrons536 in the beam travel across thegap404 between thethermionic electron source400 and thefirst electrode19 of the transducer (or other mechanical structure(s) on which charge is to be stored) and become trapped thereon. The charge trapped on the electrode19 (or other mechanical structure(s)) may cause an increase in the voltage thereof.
• The charge supplying process may continue until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, the second power source, e.g.,voltage source423, supplies a voltage equal to the desired voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the second power source, e.g.,voltage source423, and then stops. In some embodiments, the desired voltage is within a range of from about 100 volts to about 1000 volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded).
• The charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current424 supplied to thethermionic electron source400 may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying, direct current or alternating current, and/or any combination of the above.
• After a desired amount of charge has been supplied, it may be desirable to stop the flow of current to the thermionic electron source, so as to stop the heating of thethermionic electron source400 and the emission of electrons therefrom. This may be accomplished, for example, by disconnecting the first andsecond electrodes84,86 from the first power source, e.g.,voltage source422. The second power source, e.g.,voltage source423, and the third power source, e.g.,voltage source532, may also be disconnected from the micromachinedmechanical structure12.
• Notably, at the end of the charge supplying process employed in the embodiment ofFIG. 22, the first electrode19 (and/or any other portions of the structure on which charge is to be stored) is electrically isolated from all other electrically conductive structures within the chamber and outside of the chamber.
• In some embodiments, an electrical isolation of at least ten teraohms or another high resistance is provided between thefirst electrode19 and other electrically conductive structures within the chamber including, for example, each of theother electrodes20,22 and theelectrodes84,86 temporarily connected to the power source during the charge supplying process. Such a configuration helps reduce the possibility of excessive surface leakage that could otherwise lead to excessive drain of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored.
• As stated above, at the end of the charge supplying process employed in the embodiment ofFIG. 22, the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) is also electrically isolated from electrically conductive structures outside the chamber. As stated above, structures outside the chamber may have more contamination and/or greater potential for leakage current and/or drain than structures inside the chamber. Thus, providing electrical isolation from conductive structures outside of the chamber may significantly reduce leakage current and/or drain
• In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided between thefirst electrode19 and structures outside the chamber, thereby reducing the possibility of excessive leakage through the one or moremechanical structures82 to points outside the chamber that could otherwise lead to excessive drain of the electrical charge on the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored).
• As stated above, it may be desirable to reduce heat transfer from thethermionic electron source400 in order to increase the heating thereof and reduce the amount of energy needed to heat thethermionic electron source400 to a temperature at which electrons are emitted therefrom.
• In some embodiments, a vacuum or near vacuum is provided within thechamber150. The vacuum or near vacuum may help reduce (or further reduce) heat transfer within thechamber150 and thereby help to reduce or minimize the amount of energy needed to heat the thermionic electron source.
• It may also be desirable to increase the thermal resistance of the thermionic electron source. Increasing the thermal resistance of thethermionic electron source400 may increase the magnitude of the power dissipation and/or heating, and thereby help the thermionic electron source reach or exceed a temperature at which electrons are emitted therefrom.
• As stated above, the efficiency of the charge supplying process may depend, at least in part, on the surface area of the one or more portions of the thermionic electron source that face toward the electrode19 (or other mechanical structure(s) on which charge is to be stored), the surface area of the one or more portions of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the distance between the thermionic electron source and the electrode19 (or other mechanical structure(s) on which charge is to be stored).
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 23A-23J illustrate cross-sectional views an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 20A-20B andFIGS. 21A-21C, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 23A, in the exemplary embodiment, fabrication ofMEMS10 having micromachinedmechanical structure12 including an electron gun may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86, electron gun (includingthermionic electrode220 and beam shaper440) andelectrodes19,20,22, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86, electron gun (includingthermionic electrode220 and beam shaper440) andelectrodes19,20,22, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 having the electron gun may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 including electron gun is illustrated inFIGS. 23B-23J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E,10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11 andFIGS. 12A-12D). For example, with reference toFIGS. 24A and 24B,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example,FIGS. 25A and 25B).
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein (see, for example,FIGS. 25A and 25B).
• FIGS. 26A-26B andFIGS. 27A-27C illustrate plan views and cross sectional views, respectively, of a portion of another micromachinedmechanical structure12 that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated inFIGS. 26A-26B andFIGS. 27A-27C includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, an energy harvesting device), a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however, thetransducer12 is not limited to such.
• In the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B andFIGS. 27A-27C,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example first, second andthird electrodes19,20,22. The first, second andthird electrodes19,20,22 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, for example, thefirst electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. The movablemechanical structure28 is similar to the movablemechanical structure28 of thefirst electrode19 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E. The second andthird electrodes20,22 comprise fixed mechanical structures with generally rectangular shapes similar to that of the second andthird electrodes20,22 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). In this embodiment, the one or moremechanical structures82 include afirst electrode84, asecond electrode86 and athird electrode600. The one or moremechanical structures82 may have any configuration (e.g., size, shape, orientation). In the illustrated embodiment, for example, the first andsecond electrodes84,86 include fixed mechanical structures having generally rectangular shapes spaced apart from one another by a gap. The first andsecond electrodes84,86 may be disposed on opposite sides of, and equally spaced from, areference plane604. Thethird electrode600 may include a fixedmechanical structure606 and a movablemechanical structure608 that extends therefrom and includes first and second ends612,614. Thefirst end612 may connect to the fixedstructure606. Thesecond end614 may be free. In one embodiment,movable structure608 has alength616 in a range of about 100 microns to about 300 microns and awidth618 in a range of about 5 microns to about 10 microns.
• A portion of themovable structure608 may be disposed between the first andsecond electrodes84,86. In that regard, themovable structure608 may define first andsecond surfaces620,622. Thefirst surface620 may face in a direction toward afirst surface624 of thefirst electrode84 and may be spaced therefrom by afirst gap626. Thesecond surface622 may face in a direction toward afirst surface628 of thesecond electrode86 and may be spaced therefrom by asecond gap630.
• Themovable structure608 may further include acontact632 defining acontact surface634 that faces in a direction toward acontact surface636 of acontact portion638 ofelectrode19 of the transducer16 (and/or other mechanical structure(s) on which charge is to be stored). Thecontact surface634 of the movable structure and thecontact surface636 of the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may be spaced apart from one another by athird gap639. Thecontact632,contact portion638, andcontact surfaces634,636 may have any configuration (shape, size) and/or location. Thus, contact632,contact portion638, andcontact surfaces634,636 are not limited to raised contacts and/or raised contact surfaces.
• The one or moremechanical structures82 may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table for example silicon, germanium, carbon; and combinations thereof, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• One or more clearances e.g.,clearances636a,636b(FIG. 27A), may be provided between one or more portions of themovable structure608 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g.,clearances636a,636b, may reduce the possibility of friction and/or interference between the movable structure and the one or more other portions of the micromachinedmechanical structure12. In some embodiments, the one or more clearances, e.g.,clearances636a,636b, provide clearance around each surface of themovable structure608 except atend612 where themovable structure608 connects to the fixedstructure606 such that themovable structure608 is suspended from the fixedstructure606.
• Thethird electrode600 may define a contact area, e.g.,contact area600a, which may provide an electrical path between theelectrode600 and one or more other circuits and/or devices, e.g., voltage source300 (FIG. 28)).
• Referring toFIGS. 27A-27C, the micromachinedmechanical structure12 may further define one or more insulation area, e.g.,isolation area640, disposed between thesubstrate14 andthird electrode600, to provide electrical isolation between the substrate and such electrode. The one or more insulation areas, e.g.,insulation areas640, may comprise, for example, silicon dioxide or silicon nitride.
• The micromachinedmechanical structure12 may further define one or more insulation areas, e.g.,insulation area650, disposedsuperjacent electrode600 to partially, substantially or entirely surroundcontact area600aofelectrode600, as may be desired. The one or more insulation areas, e.g.,insulation area650, may comprise, for example, silicon dioxide or silicon nitride. One or more of such insulation areas, e.g.,insulation area650, may define one or more openings, e.g.,openings660, to facilitate electrical contact to theelectrode600.
• As stated above, the micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the entire contents of which, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• The one ormore encapsulation layers154 may define one or more conductive regions, e.g.,conductive region670, disposedsuperjacent electrode600 to facilitate electrical contact therewith. The one ormore encapsulation layers154 may further define one or more trenches, e.g.,trench680, disposed about one or more of the conductive regions, e.g.,conductive region670, to electrically isolate one or more of such regions from one or more other portions of the micromachinedmechanical structure12. Insulating material may be deposited in one or more of the trenches, e.g.,trench680, to form one or more isolation regions, e.g.,isolation region690.
• As stated above, the micromachined mechanical structure may further define aninsulation layer190 and aconductive layer192 disposed superjacent encapsulation layer(s)154. Theinsulation layer190 may provide electrical isolation betweenconductive layer192 and one or more other portions of the micromachinedmechanical structure12, as may be desired. Theconductive layer192 may define one or more conductive regions, e.g.,conductive region700, that form part of the electrical connection to one or more electrodes, e.g.,electrode600.
• As further described hereinafter, providing an excitation, e.g., an excitation signal on one or more of first andsecond electrodes84,86, causes themovable structure608 of thethird electrode600 to move in a lateral direction.
• In the absence of an excitation and/or stored charge, themovable structure608 may be stationary and disposed at a position that is centered about the reference plane604 (i.e., equidistant or at least approximately equidistant between the first andsecond electrodes84,86). With such positioning, the width of the gap626 (i.e., the gap separating themovable structure608 and the first electrode84) may be approximately equal to the width of the gap630 (i.e., the gap separating themovable structure608 and the second electrode86). In some embodiments, one or more portions ofthird electrode600 are resilient so that themovable structure608 bends in the presence of an excitation and returns to its original position after the excitation is removed.
• FIGS. 28A-28E illustrate one embodiment for employing the one or moremechanical structures82 to facilitate storing of electrical charge on thefirst electrode19 of thetransducer16 illustrated inFIGS. 26A-26B andFIGS. 27A-27C (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention.
• Referring toFIG. 28A, in this embodiment, one or more of the first andsecond electrodes84,86 are connected to one or more power sources that provide an excitation, e.g., excitation signals720,722, to control themovable structure608 of thethird electrode600. Thethird electrode600 is electrically connected to a first power source, e.g., avoltage source300. The excitation, e.g., excitation signals720,722, result in an electrostatic force that cause themovable structure608 of thethird electrode600 to move toward thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• Referring toFIG. 28B, as thecontact portion632 of themovable body608 moves toward thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), thegap639 between thecontact portions632,638 decreases and thecontact surface634 of themovable structure608 eventually makes contact with thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• During such contact, the first power source, e.g.,voltage source300, supplies an electric current302 that flows through thethird electrode600 to supply charge to thefirst electrode19 of the transducer (and/or other mechanical structure(s) on which charge is to be stored). The charge supplied to thefirst electrode19 of the transducer16 (or other mechanical structure(s) on which charge is to be stored) may cause an increase in the voltage thereof.
• The charge supplying process may proceed until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, the first power source, e.g.,voltage source300, supplies a voltage equal to the desired voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the above described charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the first power source, e.g.,voltage source300, and then stops. As stated above, in some embodiments, the desired voltage is within a range of from about 100 volts to about 1000 volts, e.g., 1000 volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has already been supplied thereto.
• Referring toFIG. 28C, after a desired amount of charge has been supplied, it may be desirable to break the mechanical and electrical contact between thecontact portion632 of themovable structure608 and thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In some embodiments, this may be accomplished, by removing and/or reducing the excitation, e.g., excitation signals720,722. If one or more portions offirst electrode19 are resilient, the movable structure may move away from the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) and thecontact portion632 of themovable structure608 may eventually break contact with thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) after the excitation is removed. In some embodiments, it may be advantageous to connect one or more of the first andsecond electrodes84,86 to one or more power sources that provide an excitation, e.g., excitation signals720,722, that cause themovable structure608 of thethird electrode600 to move away from thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) such that thecontact portion632 of themovable structure608 eventually breaks contact with thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). Referring toFIG. 28D, thereafter, thethird electrode600 may be disconnected from the first power source, e.g., thefirst voltage source300.
• Referring toFIG. 28E, in some embodiments, however, thecontact portion632 of themovable structure608 and thecontact portion638 of thefirst electrode19 become welded and permanently short circuited to one another during the charge storing process. For example, in some embodiments, some or all surfaces of the micromachined mechanical structure12 (includingcontact surface634 ofcontact portion632 and/orcontact surface636 of contact portion638) are so clean and/or smooth that the surface forces applied to contactsurface634 ofcontact portion632 and/orcontact surface636 ofcontact portion638 during the charge storing process are of a sufficient magnitude to cause a weld and a permanent short circuit betweensuch surfaces634,636. As a result, the electrode, e.g.,electrode600, connected to the first power source becomes permanently short circuited to thefirst electrode19 of the transducer (and/or other structure(s) on which electrical charge is to be stored). Such a configuration increases the possibility of excessive surface leakage to points within the chamber and introduces the possibility of leakage through the one or moremechanical structures82 to points outside the chamber, which in some embodiments, could result in excessive leakage and/or drain of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored.
• Thus, in some embodiments (e.g., embodiments for which the leakage and/or drain in the configuration above could be excessive), it may be advantageous to employ the one ormore structures82 of micromachinedmechanical structure12 illustrated inFIGS. 2A-2D,3A-3F, the one ormore structures82 of micromachinedmechanical structure12 illustrated inFIGS. 14A-14B,15A-15B and/or the one ormore structures82 of micromachinedmechanical structure12 illustrated inFIGS. 20A-20B,21A-21C.Such structures82 help prevent the electrode, e.g.,electrode600, connected to the power source from becoming permanently short circuited to thefirst electrode19 of the transducer (and/or other structure(s) on which electrical charge is to be stored).
• As stated above, the charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• The excitation, e.g., excitation signals720,722, supplied to the one or more electrodes, e.g.,electrodes84,86, may be single ended or differential, continuous or discontinuous, periodic or non-periodic, sinusoidal or non-sinusoidal, fixed in rate or time varying in rate, fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• FIGS. 28F-28I illustrate another embodiment for employing the one or moremechanical structures82 to facilitate storing of electrical charge on thefirst electrode19 of thetransducer16 illustrated inFIGS. 26A-26B andFIGS. 27A-27C (and/or one or more portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention.
• Referring toFIG. 28F, in this embodiment, one or more of the first andsecond electrodes84,86 are connected to one or more power sources that an excitation, e.g., excitation signals720,722, to control themovable structure608 of thethird electrode600. Thethird electrode600 is electrically connected to a first power source, e.g., avoltage source300. The excitation, e.g., excitation signals720,722, result in an electrostatic force that causes themovable structure608 of thethird electrode600 to move back and forth, such that thecontact portion632 of themovable structure608 moves toward and away from thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• Referring toFIG. 28G, as thecontact portion632 of themovable body608 moves toward thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), thegap639 between thecontact portions632,638 decreases and thecontact surface634 of thecontact portion632 of themovable structure608 eventually makes contact with thecontact surface636 of thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• During such contact, the first power source, e.g.,voltage source300, supplies an electric current302 that flows through thethird electrode600 to supply charge to thefirst electrode19 of the transducer (and/or other mechanical structure(s) on which charge is to be stored). The charge supplied to thefirst electrode19 of the transducer16 (and/or other mechanical structure(s) on which charge is to be stored) may cause an increase in the voltage thereof.
• Referring toFIG. 28H, as the contact portion of themovable body608 moves away from thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), thecontact surface634 of thecontact portion632 of themovable structure608 eventually breaks contact with thecontact surface636 of thecontact portion638 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), and the electrical current to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) stops.
• The make-break cycle and the charge supplying process (wherein charge is supplied while thecontact surface634 of thecontact portion632 is in contact with thecontact surface636 of the contact portion638) may proceed until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, the first power source, e.g.,voltage source300, supplies a voltage equal to the desired voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the above described charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the first power source, e.g.,voltage source300, and then stops. As stated above, in some embodiments, the desired voltage is within a range of from about 100 volts to about 1000 volts, e.g., 1000 volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded)
• The make-break cycle may be stopped, for example, by removing and/or reducing the excitation, e.g., excitation signals720,722, such that themovable structure608 of thethird electrode600 eventually comes to rest and/or no longer moves enough to make contact with the electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• With the make-break cycle stopped, the movable body and the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may be separated by thegap639 thereby trapping the charge stored on the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). Referring toFIG. 281, thereafter, thethird electrode600 may be disconnected from the first power source, e.g., thefirst voltage source300.
• As stated above, the charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• The excitation, e.g., excitation signals720,722, supplied to the one or more electrodes, e.g.,electrodes84,86, may be single ended or differential, continuous or discontinuous, periodic or non-periodic, sinusoidal or non-sinusoidal, fixed in rate or time varying in rate, fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• The “make” portion of the make-break cycle may deliver any amount of force to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) during the break portion of the make-break process (or cycle). Further, the make portion of the make-break cycle may comprise any type of contact between the contact portions for example but not limited to, perpendicular (e.g., head-on), tangential (e.g., brushing), and/or any combination thereof.
• The movement of themovable structure608 may include any type or types of movement. In some embodiments, the electrostatic force resulting from the excitation, e.g., the one or more excitation signals, e.g.,720,722, drives themovable structure608 into a state of mechanical resonance such that themovable structure608 defines a tapping mode cantilever. With the movable structure in a state of mechanical resonance, themovable structure608 makes a brushing contact with the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). During such brushing contact with thefirst electrode19, electric current302 flows into the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) to supply electrical charge thereto. By driving the movablemechanical structure608 into a state of mechanical resonance, a large mechanical restoring force is assured, which helps to ensure that the contact portion of the movable structure breaks contact with the contact portion of the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) during the break portion of the make-break process (or cycle) and thereby helping to prevent the movablemechanical structure608 from becoming welded and permanently short circuited to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). Repeated contact between themovable structure608 and the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), causes an increase in the amount of charge stored thereon and/or an increase in the voltage thereof.
• The movable body may comprise any suitable material, for example, a semiconductor material (whether doped or undoped), for example, silicon, germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations and/or permutations thereof.
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 29A-29J illustrate cross-sectional views an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 26A-26B andFIGS. 27A-27C, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 29A, in the exemplary embodiment, fabrication ofMEMS10 having the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B andFIGS. 27A-27C may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86,600 andelectrodes19,20,22, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86,600 andelectrodes19,20,22, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 is illustrated inFIGS. 29B-29J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E,10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11 andFIGS. 12A-12D). For example, with reference toFIGS. 30A and 30B,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example,FIGS. 31A and 31B).
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein (see, for example,FIGS. 31A and 31B).
• FIGS. 32A-32B andFIGS. 33A-33B illustrate plan views and cross sectional views, respectively, of a portion of another micromachinedmechanical structure12 that may be employed in the MEMS ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated in32A-32B andFIGS. 33A-33B includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however, thetransducer12 is not limited to such.
• In the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B andFIGS. 33A-33B,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example first, second andthird electrodes19,20,22. The first, second andthird electrodes19,20,22 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, for example, thefirst electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. The movablemechanical structure28 is similar to the movablemechanical structure28 of thefirst electrode19 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E. The second andthird electrodes20,22 comprise fixed mechanical structures with generally rectangular shapes similar to that of the second andthird electrodes20,22 of thetransducer16 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). In this embodiment, the one or moremechanical structures82 include afirst electrode84 and asecond electrode86. The one or moremechanical structures82 may have any configuration (e.g., size, shape, orientation). In the illustrated embodiment, for example, the first electrode includes a fixedmechanical structure606 and a movablemechanical structure608 that extends therefrom and includes first and second ends612,614. Thefirst end612 connects to the fixedstructure606. Thesecond end614 is free.
• The second mechanical structure includes a fixed mechanical structure.
• A portion of themovable structure608 may be disposed between thesecond electrode86 and the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In that regard, themovable structure608 may define afirst surface620 that faces in a direction toward afirst surface624 of thesecond electrode86 and may be spaced therefrom by afirst gap626. Themovable structure608 may further define acontact surface634 that faces in a direction toward acontact surface636 of acontact portion638 of electrode19 (and/or other mechanical structure(s) on which charge is to be stored) and may be spaced therefrom by agap639.
• The one or moremechanical structures82 may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table for example silicon, germanium, carbon; and combinations thereof, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• One or more clearances e.g.,clearances636a,636b(FIG. 33A), may be provided between one or more portions of themovable structure608 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g.,clearances636a,636b, may reduce the possibility of friction and/or interference between the movable structure and the one or more other portions of the micromachinedmechanical structure12. In some embodiments, the one or more clearances, e.g.,clearances636a,636b, provide clearance around each surface of themovable structure608 except atend612 where themovable structure608 connects to the fixedstructure606 such that themovable structure608 is suspended from the fixedstructure606.
• As stated above, the micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the entire contents of which, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• As further described hereinafter, providing an excitation, e.g., an excitation signal, on thesecond electrode86 causes themovable structure608 of thefirst electrode84 to move in a lateral direction.
• In the absence of an excitation and/or stored charge, themovable structure608 may be stationary and disposed at a position that is centered about the reference plane604 (i.e., equidistant or at least approximately equidistant between thesecond electrode86 and the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). With such positioning, the width of the gap626 (i.e., the gap separating themovable structure608 and the second electrode84) may be approximately equal to the width of the gap639 (i.e., the gap separating themovable structure608 and the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored)). In some embodiments, one or more portions offirst electrode84 is resilient so that themovable structure608 bends in response to the excitation, e.g., in the presence of the excitation, and returns to its original position after the excitation, is removed.
• FIGS. 34A-34D illustrate one embodiment for employing the one or moremechanical structures82 to facilitate storing of electrical charge on thefirst electrode19 of thetransducer16 illustrated inFIGS. 32A-32B andFIGS. 33A-33B (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored), in accordance with certain aspects of the present invention.
• Referring toFIG. 34A, in this embodiment, thefirst electrode84 is electrically connected to a first power source, e.g., avoltage source300. Thesecond electrode86 is connected to one or more power sources that an excitation, e.g.,excitation signal720. The excitation, e.g.,excitation signal720, results in an electrostatic force that causes themovable structure608 of thefirst electrode84 to move back and forth, such that thecontact surface634 of themovable structure608 moves toward and away from thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• Referring toFIG. 34B, as thecontact surface634 of themovable body608 moves toward thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), thegap639 between the contact surfaces634,636 decreases and thecontact surface634 of themovable structure608 eventually makes contact with thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• During such contact, the first power source, e.g.,voltage source300, supplies an electric current302 that flows through thefirst electrode84 to supply charge to thefirst electrode19 of the transducer (and/or other mechanical structure(s) on which charge is to be stored). The charge supplied to thefirst electrode19 of the transducer16 (or other mechanical structure(s) on which charge is to be stored) may cause an increase in the voltage thereof.
• Referring toFIG. 34C, as thecontact surface634 of themovable body608 moves away from thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), thecontact surface634 of themovable structure608 eventually breaks contact with thecontact surface636 of the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), and the electrical current to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) stops.
• The make-break cycle and the charge supplying process (wherein charge is supplied while thecontact surface634 of themovable structure608 is in contact with thecontact surface636 of the first electrode19 (or other mechanical structure(s) on which charge is to be stored)) may proceed until a desired amount of charge has been supplied, e.g., until the electrode19 (or other mechanical structure(s) on which charge is to be stored) has a desired voltage. In some embodiments, the first power source, e.g.,voltage source300, supplies a voltage equal to the desired voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) and the above described charge supplying process proceeds until the voltage of the electrode19 (or other mechanical structure(s) on which charge is to be stored) is equal to the voltage supplied by the first power source, e.g.,voltage source300, and then stops. As stated above, in some embodiments, the desired voltage is within a range of from about 100 volts to about 1000 volts, e.g., 1000 volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 of first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may have a resonant frequency indicative of the amount of charge supplied to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) has the desired amount of charge stored thereon), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded). The make-break cycle may be stopped, for example, by removing and/or by reducing the excitation, e.g.,excitation signal720, such that themovable structure608 of thefirst electrode84 eventually comes to rest and/or no longer moves enough to make contact with the electrode19 (and/or other mechanical structure(s) on which charge is to be stored).
• With the make-break cycle stopped, the movable body and the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) may be separated by thegap639 thereby trapping the charge stored on the electrode19 (and/or other mechanical structure(s) on which charge is to be stored). Referring toFIG. 34D, thereafter, thefirst electrode84 may be disconnected from the first power source, e.g., thefirst voltage source300.
• As stated above, the charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• Notably, at the end of the charge supplying process employed in the embodiment ofFIGS. 34A-34D, the first electrode19 (and/or any other portion of the structure on which charge is to be stored) is electrically isolated from all other electrically conductive structures within the chamber. In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided between thefirst electrode19 and other electrically conductive structures within the chamber including, for example, each of theother electrodes20,22 and theelectrodes84,86 temporarily connected to the power source during the charge supplying process. Such a configuration helps reduce the possibility of excessive surface leakage that could otherwise lead to excessive drain of the electrical charge on the one or more portions of the micromachined mechanical structure on which electrical charge is desired to be stored. In addition, at the end of the charge supplying process employed in the embodiment ofFIGS. 34A-34D, the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored) is also electrically isolated from electrically conductive structures outside the chamber. In some embodiments, an electrical isolation of at least ten teraohms or another high DC resistance is provided, thereby reducing the possibility of excessive leakage through the one or moremechanical structures82 to points outside the chamber that could otherwise lead to excessive drain of the electrical charge on the first electrode19 (and/or any other portion(s) of the structure on which charge is to be stored).
• The excitation, e.g.,excitation signal720, may be continuous or discontinuous, periodic or non-periodic, sinusoidal or non-sinusoidal, fixed in rate or time varying in rate, fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• The “make” portion of the make-break cycle may deliver any amount of force to the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) during the break portion of the make-break process (or cycle). Further, the make portion of the make-break cycle may comprise any type of contact between the contact portions for example but not limited to, perpendicular (e.g., head-on), tangential (e.g., brushing), and/or any combination thereof.
• The movement of themovable structure608 may include any type or types of movement. In some embodiments, the electrostatic force resulting from the excitation, e.g., the one or more excitation signals, e.g.,720,722, drives themovable structure608 into a state of mechanical resonance such that themovable structure608 defines a tapping mode cantilever. With the movable structure in a state of mechanical resonance, themovable structure608 makes a brushing contact with the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). During such brushing contact with thefirst electrode19, electric current302 flows into the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored) to supply electrical charge thereto. By driving the movablemechanical structure608 into a state of mechanical resonance, a large mechanical restoring force is assured, which helps to ensure that the contact portion of the movable structure breaks contact with the contact portion of the electrode19 (and/or other mechanical structure(s) on which charge is to be stored) during the break portion of the make-break process (or cycle) and thereby helping to prevent the movablemechanical structure608 from becoming welded and permanently short circuited to the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored). Repeated contact between themovable structure608 and the first electrode19 (and/or other mechanical structure(s) on which charge is to be stored), causes an increase in the amount of charge stored thereon and/or an increase in the voltage thereof.
• The movable body may comprise any suitable material, for example, a semiconductor material (whether doped or undoped), for example, silicon, germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations and/or permutations thereof.
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 35A-35J illustrate cross-sectional views an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 32A-32B andFIGS. 33A-33B, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 35A, in the exemplary embodiment, fabrication ofMEMS10 having the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B andFIGS. 33A-33B may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86,600 andelectrodes19,20,22, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86,600 andelectrodes19,20,22, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 is illustrated inFIGS. 35B-35J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E,10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11 andFIGS. 12A-12D). For example, with reference toFIGS. 36A and 36B,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example,FIGS. 37A and 37B).
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein (see, for example,FIGS. 37A and 37B).
• Thetransducer16 is not limited to the configurations of thetransducer16 illustrated inFIGS. 2A-2D,FIGS. 3A-3E,FIGS. 14A-14B,FIGS. 15A-15B,FIGS. 20A-20B,FIGS. 21A-21C,FIGS. 26A-26B and/orFIGS. 27A-27C.
• For example,FIGS. 38A-38C illustrate plan views and a cross sectional view of a portion of another micromachinedmechanical structure12 that may be employed in theMEMS10 ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated inFIGS. 38A-38C includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer but is not limited to such.
• In the micromachinedmechanical structure12 illustrated inFIGS. 38A-38C,transducer16 includes a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example first, second andthird electrodes19,20,22.
• The first, second andthird electrodes19,20,22 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, thefirst electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. The movablemechanical structure28 may include a spring portion30 (FIG. 38B) and amass portion32 and may be centered about areference plane33. Thespring portion30 may include a plurality ofseparate spring elements30a(FIG. 38B). Themass portion32 may be disposed between the second andthird electrodes20,22. The second andthird electrodes20,22 may each define a fixed mechanical structure having a generally rectangular shape. The second andthird electrodes20,22 may be disposed on opposite sides of the movablemechanical structure28 and/orreference plane33.
• The first, second andthird electrodes19,20,22 and/or other mechanical structures may be comprised of any suitable material, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide and combinations thereof, materials in column IV of the periodic table for example silicon, germanium, carbon; and combinations thereof, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• The first andsecond electrodes19,20 collectively define a first capacitance. The first andthird electrodes19,22 collectively define a second capacitance. The magnitude of the first capacitance depends on the relative positioning of the first andsecond electrodes19,20. The magnitude of the second capacitance depends on the relative positioning of the first andthird electrodes19,22.
• As further described hereinafter, exposing the micromachinedmechanical structure12 to an excitation (e.g., a vibrational excitation having a lateral component) causes the movablemechanical structure28 of thefirst electrode19 to move in a direction (e.g., in a lateral direction) that causes a change in the magnitude of the first capacitance and the magnitude of the second capacitance. In the absence of an excitation the movablemechanical structure28 may be centered between thesecond electrode20 and thethird electrode22 at which position the first capacitance and the second capacitance may be approximately equal to one another.
• One or more clearances e.g.,clearances76a,76b(FIG. 38C), may be provided between one or more portions of the movablemechanical structure28 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g.,clearances76a,76b, may reduce the possibility of friction and/or interference between the movable structure and the one or more other portions of the micromachinedmechanical structure12. In some embodiments, the one or more clearances, e.g.,clearances76a,76b, provide clearance around each surface of the movablemechanical structure28 except atend58 where the movablemechanical structure28 connects to the fixedmechanical structure26, such that the movable structure is suspended from the fixedmechanical structure26.
• With reference toFIG. 38B, in this embodiment, eachspring element30aofspring portion30 includes first and second ends56,58. Thefirst end56 may connect to themass portion32. Thesecond end58 may connect to the fixedmechanical structure26. The length and width of thespring elements30amay be about 10 microns and about 2 microns, respectively. The length of themass portion32 may be about 300 microns.
• Themass portion32 of the movablemechanical structure28 may include a plurality of elongated sections, e.g.,elongated beam sections802,804, connected via a plurality of end sections, e.g., endsections806,808. The width of thesections802,804,806,808 may be about 30 microns. In some embodiments, each of the plurality of elongated sections, e.g.,elongated beam sections802,804, comprises a straight elongated beam section and each of the plurality of end sections, e.g., endsections806,808, comprises a curved end section so that themass portion32 forms a rounded rectangle shape, as shown, a rounded triangle shape, a rounded hexagon shape or a rounded octagon shape or any other geometric shape now know or later developed that includes two or more straight elongated beam sections interconnected by two or more curved or rounded sections.
• The movablemechanical structure28 may define first andsecond surfaces40,42. Thefirst surface40 may face in a direction toward afirst surface44 of thesecond electrode20 and may be spaced therefrom by afirst gap46. Thesecond surface42 may face in a direction toward afirst surface48 of thethird electrode22 and may be spaced therefrom by asecond gap50.
• In some embodiments first, second andthird electrodes19,20,22 further defineslots809,810,812 to facilitate etching and/or removal of sacrificial material from beneath portions first, second andthird electrodes19,20,22 during fabrication of the micromachinedmechanical structure12 so that portions ofelectrodes19,20,22 are free. The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). The one or moremechanical structures82 may have any configuration. In this embodiment, the one or more mechanical structures include afirst electrode84, asecond electrode86 and abreakable link88. The one or moremechanical structures82 may each have any configuration. In the illustrated embodiment, for example, the first andsecond electrodes84,86 andbreakable link88 have configurations that are similar to that of the first andsecond electrodes84,86 andbreakable link88, respectively, of the one or moremechanical structures82 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• With reference toFIG. 38C, as stated above, the micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the entire contents of which, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• FIGS. 39A-39C illustrate stages that may be employed in the operation of thetransducer16, in accordance with certain aspects of the present invention.
• Referring toFIG. 39A, as stated above, in the absence of an excitation (e.g., vibration) the movablemechanical structure28 of thefirst electrode19 may be stationary and disposed at a position approximately centered between thesecond electrode20 and thethird electrode22. With the movablemechanical structure28 at such position, the width of thefirst gap46 may be approximately equal to the width of thesecond gap50. The charge stored on thefirst electrode19 results in a first voltage V1 across the first capacitance (e.g., defined by thesecond electrode20 and the first electrode19) and a second voltage V2 across the second capacitance (e.g., defined by thethird electrode22 and the first electrode19).
• With the movablemechanical structure28 stationary and centered between thesecond electrode20 and thethird electrode22, the first voltage V1 and the second voltage V2 may be equal to and opposite one another (or approximately equal to and opposite one another).
• The first and second voltages V1 and V2 result in laterally directed, electrostatic forces on the movablemechanical structure28. With the movablemechanical structure28 stationary and centered, as shown, the laterally directed electrostatic force due to the voltage V1 across the first capacitance may be equal to and opposite (or approximately equal to and opposite) the laterally directed, electrostatic force due to the voltage V2 across the second capacitance, so that the net electrostatic force on the movablemechanical structure28 in the lateral direction may be equal to zero.
• With reference toFIG. 39B, providing an excitation (e.g., vibration) having a lateral component, e.g.,lateral component320, causes the movablemechanical structure28 ofelectrode19 to begin to move in a lateral direction, e.g.,lateral direction322. For example, if thelateral component320 is directed toward thethird electrode22, the movablemechanical structure28 begins to move in adirection322 toward thesecond electrode20, as shown, such that the size of thefirst gap46 decreases and the size of thesecond gap50 increases. The decrease in the size of thefirst gap46 causes an increase in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19) and an electrical current out of thesecond electrode20, thereby decreasing the voltage of the first electrode and increasing the charge differential and the voltage differential across the first capacitance. The voltage The increase in the size of thesecond gap50 causes a decrease in the magnitude of the second capacitance (e.g., defined by thethird electrode22 and first electrode19) and an electrical current into thethird electrode22, thereby increasing the voltage of the second electrode and decreasing the charge differential and the voltage differential across the second capacitance.
• With reference toFIG. 39C, if thelateral component320 is directed toward thesecond electrode20, the movablemechanical structure28 begins to move in adirection324 toward thethird electrode22, such that the size of thefirst gap46 increases and the size of thesecond gap50 decreases. The increase in the size of thefirst gap46 causes a decrease in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19) and an electrical current into thesecond electrode20, which in turn decreases the charge across the first capacitance. The decrease in the size of thesecond gap50 causes an increase in the magnitude of the second capacitance (e.g., defined by thethird electrode22 and the first electrode19) and an electrical current out of thethird electrode22, which in turn increases the charge across the second capacitance.
• As stated above, the amount of the movement observed in the movable structure of thefirst electrode19 may depend at least in part on the magnitude of the excitation (e.g., vibrational energy) applied to the micromachinedmechanical structure12, the spring constant of thespring portion30 and the mass of themass portion32. In some embodiments, the mass of themass portion32 is in a range of from about one microgram (ug) to about one milligram (mg). In some embodiments, it may be advantageous to employ aspring portion30 and amass portion32 that cause the movablemechanical structure28 to have a resonant frequency equal to, or approximately equal to, a frequency of the excitation (e.g., vibrational energy to be converted to electrical energy) to be converted to electrical energy, in order to improve and/or maximize the efficiency of the transducer. The resonant frequency of a harmonic oscillator employing a spring and a mass may be expressed by the equation: resonant frequency=(k/m), where k is equal to the spring constant and m is equal to the mass. Thus, the resonant frequency of the movablemechanical structure28 may be adjusted by increasing/decreasing the spring constant of thespring portion30 and/or by increasing/decreasing the mass of themass portion32. The spring constant may be decreased by increasing thelength62 of thespring portion30 and/or by decreasing thewidth64 of the spring portion30 (or portions thereof). The spring constant may be increased by decreasing thelength62 of thespring portion30 and/or by increasing thewidth64 of the spring portion30 (or portions thereof). The mass of themass portion32 may be adjusted by changing the dimensions and/or density of one or more portions of themass portion32.
• However, there is no requirement to employ a movablemechanical structure28 having a resonant frequency equal to the frequency of the excitation (e.g., vibrational energy to be converted to electrical energy). For example, some embodiments may have one or more constraints that preclude a resonant frequency equal to the frequency of the excitation. For example, it may not be possible to increase the length of thespring portion30 and/or the dimensions or density of themass portion32 without an unacceptable increase in the size of theMEMS10 and/or the cost associated therewith.
• Thus, some embodiments employ a movablemechanical structure28 having a resonant frequency greater than the frequency of the excitation (e.g., vibrational energy to be converted to electrical energy). In some embodiments, the frequency of the excitation is less than or equal to 100 Hertz (Hz) and the resonant frequency of the movablemechanical structure28 is greater than 100 Hz, for example, in a range from greater than 100 HZ but less than or equal to 1000 Hz. Some other embodiments employ a movable structure having a resonant frequency that is less than the frequency of the excitation.
• Some embodiments may employ a movablemechanical structure28 having more than one resonant frequency. For example, some embodiments may employ more than one spring portion and/or more than one mass portion arranged in and/or a geometric shape now know or later developed that includes provides the movablemechanical structure28 with more than one spring constant and/or more than one mass.
• Some embodiments may be exposed to more than one excitation frequency. In such embodiments, the movablemechanical structure28 may have one or more resonant frequencies equal to one or more of the excitation frequencies, one or more resonant frequencies greater than one or more of excitation frequencies and/or one or more resonant frequencies less than one or more of excitation frequencies.
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 40A-40J illustrate cross-sectional views of an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 38A-38C, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 40A, in the exemplary embodiment, fabrication ofMEMS10 having micromachinedmechanical structure12 may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86, andelectrodes19,20,22, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86, andelectrodes19,20,22, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 having the thermionic electron source may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 is illustrated inFIGS. 40B-40J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E,10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11 andFIGS. 12A-12D). For example, with reference toFIG. 41,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected.
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein.
• Each of the aspects and/or embodiments disclosed herein, may be employed alone or in combination with one or more of the other aspects and/or embodiments disclosed herein, or portions thereof.
• For example, with reference toFIGS. 42-45, the vibrational energy toelectrical energy16 illustrated inFIGS. 38A-38C may be employed in conjunction with the one ormore structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 14A-14B,15A-15B (e.g., seeFIG. 42), the one ormore structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 20A-20B,21A-21C (e.g., seeFIG. 43), the one ormore structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B,27A-27C (e.g., seeFIG. 44) and/or the one ormore structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B,33A-33B (e.g., seeFIG. 45).
• Each of the aspects and/or embodiments disclosed herein may also be used in combination with other methods and/or apparatus, now known or later developed.
• Notably, the methods and/or structures disclosed herein are not limited to use in association with a micromachined mechanical structure that converts vibrational energy to electrical energy.
• For example, the methods and/or structures disclosed herein may be employed in association with any method and/or structure and/or in any type of applications including, but not limited to, energy harvesting, transducers (e.g., accelerometers, gyroscopes, microphones, pressure sensors, strain sensors, tactile sensors, magnetic sensors and/or temperature sensors), resonators, resonant filters or any combination thereof.
• FIGS. 46A-46B andFIGS. 47A-47B illustrate plan views and a cross sectional view, respectively, of a portion of another micromachinedmechanical structure12 that may be employed in theMEMS10 ofFIG. 1, in accordance with certain aspects of the present invention. As with the micromachined mechanical structure ofFIGS. 2A-2D andFIGS. 3A-3E, micromachinedmechanical structure12 illustrated inFIGS. 38A-38C includes atransducer16, which may have electrical charge supplied thereto, stored thereon and/or trapped thereon. Thetransducer16 may be any type of transducer, for example, as an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof. In this embodiment,transducer16 comprises a capacitive transducer, however, thetransducer12 is not limited to such.
• In this embodiment, the micromachinedmechanical structure12 includes atransducer16 including a plurality of mechanical structures disposed on, above and/or insubstrate14, including, for example, first andsecond electrodes19,20. The first andsecond electrodes19,20 and/or other mechanical structures may be comprised of, for example, a semiconductor material, for example, silicon, (whether doped or undoped), germanium, silicon/germanium, silicon carbide, gallium arsenide, and combinations thereof, materials in column IV of the periodic table, for example silicon, germanium, carbon; also combinations of these, for example, silicon germanium, or silicon carbide; also of III-V compounds for example, gallium phosphide, aluminum gallium phosphide, or other III-V combinations; also combinations of III, IV, V, or VI materials, for example, silicon nitride, silicon oxide, aluminum carbide, or aluminum oxide; also metallic silicides, germanides, and carbides, for example, nickel silicide, cobalt silicide, tungsten carbide, or platinum germanium silicide; also doped variations including phosphorus, arsenic, antimony, boron, or aluminum doped silicon or germanium, carbon, or combinations like silicon germanium; also these materials with various crystal structures, including single crystalline, polycrystalline, nanocrystalline, or amorphous; also with combinations of crystal structures, for instance with regions of single crystalline and polycrystalline structure (whether doped or undoped).
• The first andsecond electrodes19,20 and/or other mechanical structures may each have any configuration. In the illustrated embodiment, thefirst electrode19 includes a fixedmechanical structure26 and a movablemechanical structure28 supported thereby. Thesecond electrode20 is a fixed mechanical structure.
• With reference toFIG. 46B, the movablemechanical structure28 of thefirst electrode19 may include afirst surface40 that faces in a direction toward afirst surface44 of thesecond electrode20 and may be spaced therefrom by afirst gap46. Movablemechanical structure28 of thefirst electrode19 may include first and second ends56,58. Thefirst end56 may be free. Thesecond end58 may connect to the fixedmechanical structure26.
• The first andsecond electrodes19,20 collectively define a capacitance. The magnitude of the capacitance depends (at least in part) on the configurations of the first andsecond electrodes19,20 and on the relative positioning of the first andsecond electrodes19,20.
• As further described hereinafter, exposing the micromachinedmechanical structure12 to an excitation (e.g., acceleration, pressure, vibration, strain and/or temperature) causes the movablemechanical structure28 of thefirst electrode19 to move in a direction (e.g., in a lateral direction) that causes a change in the magnitude of the first capacitance.
• One or more clearances e.g.,clearances76a,76b(FIG. 47A), may be provided between one or more portions of the movablemechanical structure28 and one or more other portions of the micromachinedmechanical structure12. Such clearances, e.g.,clearances76a,76b, may reduce the possibility of friction and/or interference between the movable structure and the one or more other portions of the micromachinedmechanical structure12. In some embodiments, the one or more clearances, e.g.,clearances76a,76b, provide clearance around each surface of the movablemechanical structure28 except atend58 where the movablemechanical structure28 connects to the fixedmechanical structure26, such that the movable structure is suspended from the fixedmechanical structure26.
• The micromachinedmechanical structure12 further includes one or moremechanical structures82 disposed on, above and/or insubstrate14, for use in supplying, storing and/or trapping electrical charge on the first electrode19 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored). The one or moremechanical structures82 may have any configuration. In this embodiment, the one or moremechanical structures82 include afirst electrode84, asecond electrode86 and abreakable link88. The first andsecond electrodes84,86 andbreakable link88 may each have any configuration. In the illustrated embodiment, for example, the first andsecond electrodes84,86 andbreakable link88 have configurations that are similar to that of the first andsecond electrodes84,86 andbreakable link88, respectively, of the one or moremechanical structures82 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• With reference toFIG. 47B, as stated above, the micromachinedmechanical structure12 further defines achamber150 having anatmosphere152 “contained” therein. Thechamber150 may be formed, at least in part, by one or more encapsulation layer(s)154. In some embodiments, one or more of the one or more encapsulation layer(s)154 are formed using one or more of the encapsulation techniques described and illustrated in the Microelectromechanical Systems Having Trench Isolated Contacts Patent, the entire contents of which, including, for example, the features, attributes, alternatives, materials, techniques and advantages of all of the inventions, are incorporated by reference herein, although, unless stated otherwise, the aspects and/or embodiments of the present invention are not limited to such features, attributes alternatives, materials, techniques and advantages.
• Electrical charge may supplied to, stored on and/or trapped on one or more portions offirst electrode19, for example, using the stages of the embodiment described above with respect toFIGS. 6A-6D to supply, store and/or trap electrical charge on theelectrode19 of the micromachinedmechanical structure12 illustrated inFIGS. 2A-2D andFIGS. 3A-3E.
• The charge stored on thefirst electrode19 results in a voltage across the capacitance (e.g., defined by thesecond electrode20 and the first electrode19).
• With reference toFIG. 48A, providing an excitation (e.g., acceleration, pressure, vibration, strain and/or temperature) having a lateral component, e.g.,lateral component320, causes the movablemechanical structure28 ofelectrode19 to begin to move in a lateral direction. For example, if thelateral component320 is directed away from thesecond electrode20, the movablemechanical structure28 begins to move in a direction toward thesecond electrode20, as shown, such that the size of thefirst gap46 decreases. The decrease in the size of thefirst gap46 causes an increase in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19) and an electrical current out of thesecond electrode20, thereby decreasing the voltage of the first electrode and increasing the charge differential and the voltage differential across the first capacitance.
• With reference toFIG. 48B, if thelateral component320 is directed toward thesecond electrode20, the movablemechanical structure28 begins to move in adirection324 away from thesecond electrode20, such that the size of thefirst gap46 increases. The increase in the size of thefirst gap46 causes a decrease in the magnitude of the first capacitance (e.g., defined by thesecond electrode20 and first electrode19) and an electrical current into thesecond electrode20, which in turn decreases the charge across the first capacitance.
• If thetransducer16 is employed as an energy harvesting device, one or more portions of the electrical energy generated by thetransducer16 may be supplied, directly and/or indirectly, to one or more circuits and/or devices, and/or used, directly and/or indirectly, in powering one or more portions of one or more circuits and/or devices. For example, one or more of the voltages and/or one or more of the currents generated by thetransducer16 may be supplied, directly or indirectly, to one or more circuits and/ordevices326, and/or used, directly and/or indirectly, in powering one or more portions of one or more circuits and/ordevices326.
• If thetransducer16 is employed as a sensor (e.g., a vibration sensor and/or accelerometer), one or more portions of the electrical energy generated by thetransducer16 may be supplied, directly and/or indirectly, to one or more circuits and/or devices, and/or used directly and/or indirectly, as an indication of one or more physical quantities (e.g., vibration and/or acceleration) sensed by thetransducer16. For example, one or more of the electrical signals (e.g., one or more of the voltages (e.g., the voltage across the first and/or second capacitance) generated by thetransducer16 and/or one or more of the currents (e.g., the current into and/or out of the first and/orsecond electrodes19,20)) generated by thetransducer16, may be supplied, directly or indirectly, to one or more circuits and/or devices and/or employed as an indication of the one or more physical quantities (e.g., vibration and/or acceleration) sensed by thetransducer16.
• The amount of the movement observed in the movable structure of thefirst electrode19 may depend at least in part on the magnitude of the excitation (e.g., vibrational energy) applied to the micromachinedmechanical structure12.
• The micromachinedmechanical structure12 may be fabricated using one or more of the methods disclosed herein and/or any other suitable technique.
• FIGS. 49A-49J andFIGS. 50A-50J illustrate cross-sectional views of an exemplary embodiment of the fabrication of the portion of MEMS ofFIGS. 46A-46B andFIGS. 47A-47B, including encapsulation that may be employed therewith, at various stages of the process, according to certain aspects of the present invention.
• With reference toFIG. 49A andFIG. 50A, in the exemplary embodiment, fabrication ofMEMS10 having micromachinedmechanical structure12 withtransducer16 may begin with an SOI substrate partially formed device including mechanical structures, e.g.,electrodes84,86, andelectrodes19,20, disposed on a firstsacrificial layer220, for example, silicon dioxide or silicon nitride. The mechanical structures, e.g.,electrodes84,86, andelectrodes19,20, may be formed using well-known deposition, lithographic, etching and/or doping techniques as well as from well-known materials (for example, semiconductors such as silicon, germanium, silicon-germanium or gallium-arsenide).
• Thereafter, the processing ofMEMS10 may proceed in the same manner as described above with respect toFIGS. 4B-4J. In this regard, an exemplary fabrication process ofMEM10 includingtransducer16 is illustrated inFIGS. 49A-49J andFIGS. 50B-50J. Because the processes are substantially similar to the discussion above with respect toFIGS. 4B-4J, for the sake of brevity, that discussion will not be repeated.
• As stated above, some embodiments of the present invention may be implemented in conjunction with one or more of the thin film encapsulation techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication incorporated by reference herein. In this regard, any and all of the embodiments described herein may employ one or more of the structures and/or techniques disclosed in the Microelectromechanical Systems and Method of Encapsulating Patent Application Publication. The present invention may also be employed in conjunction with wafer-bonding encapsulation techniques.
• As also stated above,MEMS10 may include one or more other circuits and/or devices, e.g., other circuits and/ordevices226,330 (FIGS. 10A-10L), charge storing circuit332 (FIGS. 10B-10E,10K-10L), DC/DC converter circuit362 (FIGS. 10E-10G,10L), data processing electronics386 (FIG. 11 andFIGS. 12A-12D) and/or interface circuitry388 (FIG. 11A andFIGS. 12A-12D). For example, with reference toFIG. 51,integrated circuits390 may be fabricated using conventional techniques after definition ofmechanical structure12 using, for example, the techniques described and illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent.
• Further, the various structures of the micromachinedmechanical structure12 may have any orientation including longitudinal, lateral, vertical any combination thereof. As stated above, any of the embodiments and/or techniques described herein may be implemented in conjunction with micromachinedmechanical structures12 having one or more transducers or sensors which may themselves include multiple layers that are vertically and/or laterally stacked or interconnected as illustrated in Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent, each of which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent that include multiple layers of mechanical structures, contacts areas and buried contacts that are vertically and/or laterally stacked or interconnected (see, for example,FIGS. 52A and 52B).
• Moreover, the present inventions may implement the anchors and techniques of anchoringmechanical structures16 to substrate14 (as well as other elements of MEMS10) described and illustrated in the Anchors for Microelectromechanical Systems Patent, which is incorporated by reference herein. Accordingly, any and all of the inventions and/or embodiments illustrated and described herein may be implemented in, and/or employed in conjunction with, any of the embodiments described and illustrated in the Anchors for Microelectromechanical Systems Patent, implemented in conjunction with the inventions described and illustrated herein (see, for example,FIGS. 52A and 52B).
• As stated above, each of the embodiments set forth herein may be employed alone and/or in combination with one or more other embodiments set forth herein.
• Thus, for example, with reference toFIGS. 53-56, thetransducer16 illustrated inFIGS. 46A-46B and47A-47B may be employed in conjunction with the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 14A-14B,15A-15B (e.g., seeFIG. 53), the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 20A-20B,21A-21C (e.g., seeFIG. 54), the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B,27A-27C (e.g., seeFIG. 55) and/or the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B,33A-33B (e.g., seeFIG. 56).
• As stated above, the methods and/or structures disclosed herein are not limited to use in association with a micromachined mechanical structure that converts vibrational energy to electrical energy. Rather, the methods and/or structures disclosed herein may be employed in association with any method and/or structure and/or in any type of applications including, but not limited to, energy harvesting, transducers (e.g., accelerometers, gyroscopes, microphones, pressure sensors, strain sensors, tactile sensors, magnetic sensors and/or temperature sensors), resonators, resonant filters or any combination thereof.
• For example, the methods and/or structures disclosed herein may be employed in association with micromachined mechanical structures that utilize a transducer, including, but not limited to, microphones, acceleration sensors, resonators and gyroscopes. The ability to store charge on one or more portions of such structures may improve the level of performance provided by the structure, in whole or in part. For example, the ability to store charge may facilitate the use of a higher operating voltage, and thereby increase the efficiency and/or the signal to noise ratio of the device.
• In addition, as stated above, the ability to store charge on one or more portions of a structure may provide the structure and/or a device employing the structure with the ability to operate and/or supply one or more signals without a battery, an internal power supply and/or external power supply. In some embodiments, for example, a device, e.g., a microphone, includes with atransducer16 that is employed as a sensor and operates and/or supplies one or more signals without a battery, an internal power supply and/or external power supply. Notably, a device may employ atransducer16 as a sensor with or without an associatedtransducer16 employed as anenergy harvesting device325.
• FIGS. 57A-57F illustrate various embodiments of amicrophone900 that employ atransducer16 as a sensor, in conjunction with one or more circuits ordevices910 that may be coupled thereto, in accordance with certain aspects of the present invention. In these embodiments,microphone900 includes ahousing902, aninput port904 andtransducer16 in accordance with one or more aspects of the present invention. Thetransducer16 may be coupled to theinput port904. For example, movable mechanical structure28 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)) of first electrode19 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)) may be in mechanical, electrical and/or flow communication with theinput port904. In operation,acoustic energy906 may be supplied to theinput port904. One or more portions of the acoustic energy may cause movement of the movable structure, e.g., movable structure28 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)), andtransducer16 may generate one or more signals (e.g., one or more voltages and/or currents) at one or more of electrodes, e.g., electrode20 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56), in response thereto.
• In some embodiments, one or more portions oftransducer16 has electrical charge stored thereon in accordance with one or more aspects of the present invention. For example, electrical charge may be stored on an electrode (see for example, first electrode19 (FIGS. 2A-2C,3A-3E14A-14B,15A-15B,20A-20B,21A-21C,26A-26B,27A-27C,32A-32B,33A-33B,38A-38C,42-45,46A-46B,47A-47B,53-56)). In some such embodiments,transducer16 may be able to operate and/or supply one or more of the one or more signals without a battery, an internal power supply and/or an external power supply.Microphone900 may be coupled to acommunication system908 that may couplemicrophone900 and/ortransducer16 to one or more circuits and/ordevices910, e.g., a receiver and/or processor.Communication system908 may include one or more communication links, e.g.,communication link912. With reference toFIG. 57B, in some embodiments, one or more of the one or more signals fromtransducer16 may be supplied throughcommunication system908 to the one or more circuits and/ordevices910.
• With reference toFIG. 57C, in one embodiment,microphone900 further includes one or more circuits and/ordevices914 coupled to thetransducer16. The one or more circuits and/or devices may further be coupled to thecommunication system908, which may in turn couple the one or more circuits and/ordevices914 to the one or more circuits and/ordevices910. In this embodiment, one or more of the one or more signals from thetransducer16 may be supplied to the one or more circuits and/ordevices914, which may generate one or more signals in response thereto. One or more of the one or more signals generated by the one or more circuits and/ordevices914 may be supplied to thecommunication system908, which may supply one or more of the one or more signals to the one or more circuits and/ordevices910. One or more of the signals generated by the one or more circuits and/ordevices914 may be indicative of the acoustical energy supplied to input port ofmicrophone900 and/or the one or more signals generated by thetransducer16 in response thereto.
• With reference toFIG. 57E, in some embodiments, the one or more circuits and/ordevices914 includedata processing electronics386 and/orinterface circuitry388. One or more of the one or more signals from thetransducer16 may be supplied to the data processing electronics and/or interface circuitry, which may generate one or more signals in response thereto. In some embodiments, for example, one or more signals from thetransducer16 may be supplied todata processing electronics386, which may generate one or more signals in response thereto. One or more of the signals generated by thedata processing electronics386 may be supplied tointerface circuitry388, which may generate one or more signals in response thereto.Interface circuitry388 may be a portion ofcommunication system908, which may supply the signal from theinterface circuitry388 to the one or more circuits and/ordevices910.
• With reference toFIG. 57D andFIG. 57F, in some embodiments,microphone900 includes anenergy harvesting device325, for example, anenergy harvesting device325 that receives vibrational energy (e.g., a portion ofacoustic energy906 and/or vibrational energy from another source of vibrational energy) and converts at least a portion of such energy to electrical energy. One or more portions of such electrical energy may be supplied, directly and/or indirectly, to thetransducer16 and/or one or more portions of the one or more circuits and/ordevices914 and/or used, directly and/or indirectly, to power one or more portions of thetransducer16 and/or one or more portions of the one or more circuits and/ordevices914, e.g.,data processing circuitry386 and/orinterface circuitry388 disposed in themicrophone900. In some embodiments, for example,microphone900 may include apower conditioning circuit360 that receives one or more portions of the electrical energy generated by theenergy harvesting device325 and generates a regulated voltage therefrom. The regulated voltage may be supplied, directly and/or indirectly, to thetransducer16 and/or the one or more circuits and/ordevices914 and may be used, directly and/or indirectly, in powering one or more portions of thetransducer16 and/or one or more portions of the one or more circuits and/ordevices914 or for any other purpose.
• In some embodiments,transducer16 and/or one or more circuits and/ordevices914 are powered entirely by one or more portions of the electrical power generated by theenergy harvesting device325, such thattransducer16, one or more circuits and/ordevices914 and/or adevice employing transducer16 and/or one or more circuits and/ordevices914 are able to operate and/or supply information indefinitely (or at least a period of time), without any need for a battery and/or an external power supply.
• In some embodiments, the one or more circuits and/ordevices914, e.g.,data processing circuitry386 andinterface circuitry388, are disposed in or on and/or integrated in or on thesame MEMS10 astransducer16. In some embodiments, the one or more circuits and/ordevices914, e.g.,data processing circuitry386 andinterface circuitry388 are disposed in or on and/or integrated in or on thesame MEMS10 asenergy harvesting device325. In some embodiments,transducer16 and the one or more circuits and/ordevices914, e.g.,data processing circuitry386 andinterface circuitry388 are disposed in or on and/or integrated in or on thesame MEMS10 asenergy harvesting device325. Notably, althoughFIGS. 57A-57F illustrate various embodiments of thetransducer16,energy harvesting device325 and other circuits and/ordevices914 in association with amicrophone900, it should be understood that any of the aspects and/or embodiments described herein may be employed in and/or in association with any type of circuit, device, system and/or method.
• Indeed, as stated above, it should be understood thattransducer16 may be any type of transducer, for example, an energy harvesting device, a sensor (e.g., an accelerometer, a gyroscope, a microphone, a vibration sensor, a pressure sensor, a strain sensor, a tactile sensor, a magnetic sensor and/or a temperature sensor), a resonator, a resonant filter, and/or a combination thereof.
• Moreover, the aspects and/or embodiments described herein may be employed in and/or in association with any type of circuit, device, system and/or method, for example, but not limited to any type of accelerometers, gyroscopes, vibration sensors, acoustic sensors, pressure sensors, strain sensors, tactile sensors, magnetic sensors, optical, temperature sensors, and/or optical or video sensors, resonators, resonant filters or any combination thereof, in any type of application, for example, but not limited to microphones, automobile tires (including, for example, but not limited to tire pressure, vibration, and/or temperature sensors), weather sensors (including, for example, but not limited to air pressure, temperature, and/or wind speed sensors), security (including, for example, but not limited to audio and/or video sensors) and industrial process (pressure, vibration, and/or temperature sensors), which may or may not include communication system via a communication link, for example, but not limited to a wireless communication link.
• In accordance with further aspects of the present invention, the ability to store charge on one or more portions of a structure may be used to trim and/or change a resonant frequency of one or more resonators, gyroscopes and/or other type of mechanical structure. As stated above, the resonant frequency of a mechanical structure may depend at least in part on the amount of charge stored thereon. Thus, the resonant frequency of a resonator, gyroscope and/or other type of mechanical structure may be changed by storing electrical charge, and/or by changing the amount of stored electrical charge, on a portion of the mechanical structure.
• For example, with reference toFIGS. 38A-38C, in some embodiments, movablemechanical structure28 oftransducer16 is a resonator, for example, a closed-ended or double clamped tuning fork resonator, to generate a reference frequency. In such embodiments,elongated sections802,804 may define beams or tines of a resonator and may be anchored to thesubstrate14 by the fixedmechanical structure26, which may define an anchor.Electrodes20,22, which may be fixed electrodes, may be employed to induce a force toelongated sections802,804, to cause theelongated sections802,804 to oscillate (in-plane).
• If the resonant frequency of the resonator is not equal to a desired reference frequency, one or more of the one or moremechanical structures82 may be employed to supply, store and/or trap electrical charge on the first electrode19 (and/or one or more other portions of micromachined mechanical structure12) and thereby cause a change in the resonant frequency so that the resonator has a new resonant frequency that is closer to a desired reference frequency.
• As stated above, the resonant frequency of a mechanical structure may depend at least in part on the amount of charge stored thereon. Thus, the resonant frequency of a resonator and/or gyroscope may be changed by storing electrical charge, and/or by changing the amount of stored electrical charge, on a portion of the mechanical structure.
• With reference toFIG. 58A, in another embodiment, aresonator1010, e.g., a closed-ended or double-clamped tuning fork resonator, includes beams ortines1012aand1012b. Thebeams1012aand1012bare anchored tosubstrate14 viaanchors1016aand1016b. The fixedelectrodes1018aand1018bare employed to induce a force tobeams1012aand1012bto cause the beams to oscillate (in-plane). Such resonator architectures are often susceptible to changes in mechanical frequency ofresonator1010 by inducing strain intoresonator beams1012aand1012bas a result of packaging stress. As a result, theresonator1010 may not have the desired resonant frequency. It may thus be desirable to supply, store and/or trap electrical charge on one or portions ofresonator1010, e.g., one or more portions ofanchors1016aand1016b, to cause a change in the resonant frequency ofresonator1010 so that theresonator1010 has a new reference frequency that is closer to a desired resonant frequency.
• In that regard,resonator1010 may be employed in conjunction with the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 2A-2C,3A-3E, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 14A-14B,15A-15B, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 20A-20B,21A-21C, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B,27A-27C and/or the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B,33A-33B, in order to store electrical charge on one or more portions ofresonator1010, e.g., on beams ortines1012a,1012b.
• FIG. 58B illustrates aflowchart1020 of stages in a process that may be employed in supplying, storing and/or trapping electrical charge on thefirst electrode19 of the transducer16 (and/or any other portion(s) of the micromachinedmechanical structure12 on which charge is to be stored) to trim the resonant frequency of themovable structure28, according to certain aspects of the present invention. With reference toFIG. 58B, in afirst stage1022, the resonant frequency of the resonator is determined. Thereafter, in astage1024, a difference between the measured resonant frequency and the desired resonant frequency is determined. At astage1026, the difference is compared to a reference. If the magnitude of the difference is less than the reference, then execution passes to stage1028 and no charge is supplied to and/or removed from thefirst electrode19. Otherwise, execution passes to stage1030. If the resonant frequency is less than the desired resonant frequency, then electrical charge is supplied to thefirst electrode19. At astage1032, if the resonant frequency is greater than the desired resonant frequency, then an amount of electrical charge is removed from thefirst electrode19. The stages in the process are repeated until the difference between the measured resonant frequency and the desired resonant frequency is less than the reference.
• It should be understood that movable structures and resonators are not limited to the movable structures and resonators described above.
• In accordance with further aspects of the present invention, the ability to supply, store and/or trap electrical charge may be employed in providing an electrostatic repulsive force and/or an electrostatic attractive force on one or more mechanical structures.
• FIG. 59 illustrates a block diagram of one embodiment of electrostatic repulsion, in accordance with certain aspects of the present invention. In the illustrated embodiment, electrical charge is supplied to, stored on and/or trapped on two or more portions of a micromachinedmechanical structure12, e.g., first andsecond portions1100,1102, thereby resulting in an electrostatic repulsive force. If one or more of theportions1100,1102 is movable, the electrostatic repulsive force may cause the one or more of theportions1100,1102 to move.
• In one embodiment, electrostatic repulsion and/or electrostatic attraction is employed in association with thetransducer16 illustrated inFIGS. 2A-2D,3A-3E,6A-6D,7A-7C,8A-8B,9A-9B,13A-13B,FIGS. 14A-14B,15A-15B,16,18A-18B,19A-19B,FIGS. 20A-20B,21A-21C,22,24A-24B,25A-25B,FIGS. 26A-26B,27A-27C,28A-28I,30A-30B,31A-31B, andFIGS. 32A-32B,33A-33B,34A-34D,36A-36B and37A-37B.
• FIGS. 60A-60B illustrate plan views of a portion of the micromachinedmechanical structure12 showing stages that may be employed in association with providing electrostatic repulsion and/or electrostatic attraction in association with thetransducer16 illustrated inFIGS. 2A-2D,3A-3E,6A-6D,7A-7C,8A-8B,9A-9B,13A-13B,FIGS. 14A-14B,15A-15B,16,18A-18B,19A-19B,FIGS. 20A-20B,21A-21C,22,24A-24B,25A-25B,FIGS. 26A-26B,27A-27C,28A-28I,30A-30B,31A-31B, andFIGS. 32A-32B,33A-33B,34A-34D,36A-36B and37A-37B, in accordance with certain aspects of the present invention.
• Referring toFIG. 60A, the charge stored on thefirst electrode19 results in a first voltage V1 across the first capacitance (e.g., defined by thesecond electrode20 and the first electrode19) and a second voltage V2 across the second capacitance (e.g., defined by thethird electrode22 and the first electrode19). With themovable structure28 stationary and centered between thesecond electrode20 and thethird electrode22, the first voltage V1 and the second voltage V2 may be equal to and opposite one another (or approximately equal to and opposite one another).
• In the absence of an excitation (e.g., the electrostatic repulsion force and/or electrostatic attraction force to be provided) the movablemechanical structure28 of thefirst electrode19 may be stationary and disposed at a position approximately centered between thesecond electrode20 and thethird electrode22. With the movablemechanical structure28 at such position, the width of thefirst gap46 may be approximately equal to the width of thesecond gap50.
• The first and second voltages V1 and V2 result in laterally directed, electrostatic forces on themovable structure28. With themovable structure28 stationary and centered, as shown, the laterally directed electrostatic force due to the voltage V1 across the first capacitance may be equal to and opposite (or approximately equal to and opposite) the laterally directed, electrostatic force due to the voltage V2 across the second capacitance, so that the net electrostatic force on themovable structure28 in the lateral direction may be equal to zero.
• With reference toFIG. 60B, supplying charge to and/or removing charge from one or more of second andthird electrodes20,22 (or other mechanical structure(s)) results in an electrostatic repulsive and/or attractive force, respectively, that causes themovable structure28 of thefirst electrode19 to move toward and/or away, respectively, from one or more of the second andthird electrodes20,22 (and/or other mechanical structure(s)).
• In illustrated embodiment, for example, electrical charge is supplied to thesecond electrode20. Because charge is stored and/or trapped on the first electrode19 (and/or other mechanical structures), the electrical charge supplied to thesecond electrode20 results in an electrostatic repulsive force that causes themovable structure28 of thefirst electrode19 to move in a direction, e.g., direction away from thesecond electrode20 and toward thethird electrode22, such that the size of thefirst gap46 increases and the size of thesecond gap50 decreases. Notably, if charge was not trapped on thefirst electrode19, the charge supplied to thesecond electrode20 would result in an attractive force, rather than a repulsive force.
• If electrical charge is caused to flow from thethird electrode22, an electrostatic attractive force also results and causes themovable structure28 of thefirst electrode19 to move in a direction away from thesecond electrode20 and toward thethird electrode22, such that the size of thefirst gap46 increases and the size of thesecond gap50 decreases.
• The amount of the movement observed in the movable structure of thefirst electrode19 may depend at least in part on the magnitude of the electrostatic repulsive and/or attractive force, the spring constant of thespring portion30 and the mass of themass portion32. As stated above, in some embodiments, the mass of themass portion32 is in a range of from 0.01 milligram or about 0.01 milligram to one milligram or about one milligram.
• Notably, electrostatic repulsion may be employed with or without electrostatic attraction. Similarly, the electrostatic attraction may be employed with or without electrostatic repulsion.
• In some embodiments, electrical charge may be supplied to multiple structures and/or removed from multiple structures such that multiple electrostatic repulsive forces and/or multiple electrostatic attractive forces are provided.
• Notably, the electrical charge may be supplied to and/or caused to flow from one or more of the second and/orthird electrodes20,22 (and/or other mechanical structure(s)) before, during and/or after supplying, storing and/or trapping electrical charge on the first electrode19 (and/or other mechanical structure(s)).
• One embodiment for supplying electrical charge to the second electrode20 (and/or other mechanical structure(s) on which charge is to be supplied to result in the electrostatic repulsive force) is as follows. Thesecond electrode20 is electrically connected to a first power source, e.g., afirst voltage source1104. The first power source, e.g.,first voltage source1104, supplies an electric current1106 that flows to the second andthird electrodes84,86 (and/or other mechanical structure(s)) to supply electrical charge thereto.
• The charge supplying process may continue until a desired amount of charge has been supplied, e.g., until the electrode20 (and/or other mechanical structure(s)) has a desired voltage. In some embodiments, first power source, e.g.,first voltage source1104, supplies a voltage that is equal to the voltage desired for second electrode20 (and/or other mechanical structure(s)), and the charge supplying process proceeds until the voltage of the electrode20 (or other mechanical structure(s)) is equal to the voltage supplied by the first power source, e.g.,voltage source1104, and then stops. In some embodiments, the desired voltage is within a range of from about 100 volts to about one thousand volts.
• In some embodiments,MEMS10 has one or more characteristics (e.g. a voltage, a resonant frequency) indicative of the amount of charge that has been supplied to the second electrode20 (and/or other mechanical structure(s)). In such embodiments, one or more of such characteristics may be measured and compared to one or more reference magnitudes to determine whether the desired amount of charge has been supplied. For example, movablemechanical structure28 offirst electrode19 may have a resonant frequency indicative of the amount of charge supplied to the second electrodes20 (and/or other mechanical structure(s)). The resonant frequency of the movablemechanical structure28 may thus be measured and compared to a reference magnitude indicative of a resonant frequency that would be exhibited by the movablemechanical structure28 if the second electrode20 (and/or other mechanical structure(s)), so as to determine whether the desired amount of charge has been supplied thereto. The charge supplying process may be stopped if it is determined that the desired amount of charge has been supplied (e.g., reached or exceeded).
• The charge supplying process may be continuous or discontinuous (periodic or non-periodic), fixed in rate or time varying in rate, and/or combinations thereof. In that regard, the electric current1106 may be continuous or discontinuous (e.g., periodic or non-periodic), fixed in magnitude or time varying in magnitude, direct current or alternating current, and/or any combination of the above.
• If it is desired to reduce and/or stop the electrostatic repulsive force, it may be desirable to turn off thefirst power source1104 and/or to disconnect the first power source, e.g.,first voltage source1104, from the micromachinedmechanical structure12 and/or the second electrode20 (or other mechanical structure(s) on which charge was supplied to result in the electrostatic repulsive force).
• In some embodiments, electrical charge is caused to flow from the third electrode22 (and/or other mechanical structure(s)) using one or more of the structures and/or methods described above for supplying electrical charge to the second electrode20 ((and/or other mechanical structure(s).
• As stated above, each of the aspects and/or embodiments set forth herein may be employed alone and/or in combination with one or more other aspects and/or embodiments set forth herein.
• In that regard, in some embodiments, it may be desirable to store and/or trap the electrical charge supplied to second20 (and/or any other mechanical structure(s)). To that effect, in some embodiments, one or more of the structures and/or techniques disclosed herein to store charge on the first electrode19 (and/or other mechanical structure(s)) may be employed to supply, store and/or trap electrical charge on the second electrodes20 (and/or any other mechanical structure(s)), such as, for example, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 2A-2D,3A-3E, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 14A-14B,15A-15B, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 20A-20B,21A-21C, the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 26A-26B,27A-27C and/or the one or moremechanical structures82 of the micromachinedmechanical structure12 illustrated inFIGS. 32A-32B,33A-33B.
• It should also be understood that the electrostatic repulsion and/or electrostatic attraction illustrated inFIG. 59 and/orFIG. 60 may also be employed in association with thetransducer16 illustrated inFIGS. 38A-38C,39A-39C,40A-40J,41,42-45 (see for example,FIG. 61) and/or thetransducer16 illustrated inFIGS. 46A-46B,47A-47B,48A-48B,49A-49J,50A-50J,51,52A-52B and53-56 (see for example,FIG. 62).
• In some embodiments, the resonant frequency of a resonator, gyroscope and/or other type of mechanical structure depends at least in part on forces applied thereto. In such embodiments, the resonant frequency of the resonator, gyroscope and/or other type of mechanical structure, may be changed by providing and/or changing an electrostatic force thereon.
• In accordance with further aspects of the present invention, an electrostatic repulsive force and/or an electrostatic attractive force may be employed to change the resonant frequency of a mechanical structure.
• For example, with reference toFIGS. 38A-38C, in some embodiments, movablemechanical structure28 oftransducer16 is employed as a resonator, for example, a closed-ended or double clamped tuning fork resonator, to generate a reference frequency. In such embodiments,elongated sections802,804 may define beams or tines of a resonator and may be anchored to thesubstrate14 by the fixedmechanical structure26, which may define an anchor.Electrodes20,22, which may be fixed electrodes, may be employed to induce a force toelongated sections802,804, to cause theelongated sections802,804 to oscillate (in-plane).
• If the resonant frequency of the resonator is not equal to a desired reference frequency, one or more electrostatic repulsive forces and/or one or more electrostatic attractive forces may be provided to cause a change in the resonant frequency such that the resonator has a new resonant frequency that may be closer to the desired reference frequency.
• In some embodiments, an electrostatic attractive force has the effect of reducing the resonant frequency of the resonator, which is similar to the effect that would be provided by providing the resonator with a softer spring. Thus, in the event that the resonant frequency of a resonator is greater than a desired resonant frequency, the availability of an electrostatic attractive force provides the capability to reduce the resonant frequency, sometimes referred to as tuning the resonant frequency down, so that the resonant frequency may be closer to the desired resonant frequency.
• In some embodiments, an electrostatic repulsive force has the effect of increasing the resonant frequency of the resonator, which is similar to the effect that would be provided by providing the resonator with a firmer spring. Thus, in the event that the resonant frequency of a resonator is less than a desired resonant frequency, the availability of an electrostatic attractive force provides the capability to increase the resonant frequency, sometimes referred to as tuning the resonant frequency up, so that the resonant frequency may be closer to the desired resonant frequency.
• In some embodiments, without the availability of an electrostatic repulsive force, there is no capability to tune the resonant frequency up. Thus, the availability of an electrostatic repulsive force may help provide a wider trimming range and may thereby help relax manufacturing constraints and/or allow resonator designers more design freedom.
• In some embodiments, electrostatic attractive and electrostatic repulsive forces are employed as follows. An electrostatic attractive force is employed to reduce the resonant frequency in the event that the resonant frequency is greater than the desired resonant frequency. An electrostatic repulsive force is employed to increase the resonant frequency in the event that the resonant frequency is less than the desired resonant frequency.
• FIG. 63 illustrates aflowchart1120 of stages in a process for employing an electrostatic repulsive force and/or an electrostatic attractive force to increase and/or decrease the resonant frequency of a movable structure, according to certain aspects of the present invention.
• With reference toFIG. 63, in afirst stage1122, the resonant frequency of the resonator is determined. Thereafter, in astage1124, a difference between the measured resonant frequency and the desired resonant frequency is determined. At astage1126, the difference is compared to a reference. If the magnitude of the difference is less than the reference, then execution passes to stage1128 and no charge is supplied to and/or removed from thefirst electrode19. Otherwise, execution passes to stage1130. If the resonant frequency is less than the desired resonant frequency, then an electrostatic repulsive force may be provided and/or increased, which has the effect of increasing the resonant frequency of the resonator.
• If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a positive voltage, the electrostatic repulsive force may be provided and/or increased by supplying charge to the second electrode20 (and/or other structure associated with providing the electrostatic repulsive force). If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a negative voltage, the electrostatic repulsive force may be provided and/or increased by removing charge from the second electrode20 (and/or other structure associated with providing the electrostatic repulsive force).
• In some embodiments, if an electrostatic attractive force is present, the electrostatic attractive force may be decreased, in addition to and/or in lieu of providing and/or increasing the electrostatic repulsive force, which may have the effect of increasing the resonant frequency of the resonator. If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a positive voltage, the electrostatic attractive force may be decreased by supplying charge to the third electrode22 (and/or other structure associated with providing the electrostatic attractive force). If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a negative voltage, the electrostatic attractive force may be decreased by removing and/or causing charge to flow from the third electrode22 (and/or other structure associated with providing the electrostatic attractive force).
• At astage1132, if the resonant frequency is greater than the desired resonant frequency, then an electrostatic attractive force may be provided and/or increased, which has the effect of decreasing the resonant frequency of the resonator. If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a positive voltage, the electrostatic attractive force may be provided and/or increased by removing and/or causing charge to flow from the third electrode22 (and/or other structure associated with providing the electrostatic attractive force). If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a negative voltage, the electrostatic attractive force may be provided and/or increased by supplying charge to the second electrode22 (and/or other structure associated with providing the electrostatic attractive force).
• In some embodiments, if an electrostatic repulsive force is present, the electrostatic repulsive force may be decreased, which has the effect of decreasing the resonant frequency of the resonator, in addition to and/or in lieu of providing and/or increasing the electrostatic attractive force. If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a positive voltage, the electrostatic repulsive force may be decreased by removing and/or causing charge to flow from the second electrode20 (and/or other structure associated with providing the electrostatic repulsive force). If the first electrode19 (and/or other mechanical structure to which the electrostatic force is to be applied thereto) has a negative voltage, the electrostatic repulsive force may be decreased by supplying charge to the second electrode20 (and/or other structure associated with providing the electrostatic repulsive force).
• In some embodiments, the stages in the process may be repeated until the difference between the measured resonant frequency and the desired resonant frequency is less than the reference.
• Notably, in some embodiments, electrostatic repulsion is employed with or without electrostatic attraction. Similarly, in some embodiments, electrostatic attraction is employed with or without electrostatic repulsion.
• As stated above, movable structures and resonators are not limited to the movable structures and resonators described above.
• Moreover, as stated above, the aspects and/or embodiments described herein may be employed in and/or in association with any type of circuit, device, system and/or method, for example, but not limited to any type of accelerometers, gyroscopes, vibration sensors, acoustic sensors, pressure sensors, strain sensors, tactile sensors, magnetic sensors, optical, temperature sensors, and/or optical or video sensors, resonators, resonant filters or any combination thereof, in any type of application, for example, but not limited to microphones, automobile tires (including, for example, but not limited to tire pressure, vibration, and/or temperature sensors), weather sensors (including, for example, but not limited to air pressure, temperature, and/or wind speed sensors), security (including, for example, but not limited to audio and/or video sensors) and industrial process (pressure, vibration, and/or temperature sensors), which may or may not include communication system via a communication link, for example, but not limited to a wireless communication link.
• Again, there are many inventions described and illustrated herein.
• Each of the aspects and/or embodiments set forth herein may be employed alone, in combination with one or more other aspects and/or embodiments set forth herein and/or in combination with one or more other structures and/or methods now known or later developed. Thus, for example, each of the aspects and/or embodiments disclosed herein, may be employed alone or in combination with one or more of the other aspects and/or embodiments disclosed herein, or portions thereof. In addition, each of the aspects and/or embodiments disclosed herein may also be used in combination with other methods and/or apparatus, now known or later developed. For example, the methods and/or structures disclosed herein may be employed separately and/or in association with any methods and/or structures, whether know known or later developed, and/or in any applications including, but not limited to, energy harvesting, transducers (e.g., accelerometers, gyroscopes, microphones, pressure sensors, strain sensors, tactile sensors, magnetic sensors and/or temperature sensors), resonators, resonant filters or any combination thereof.
• Moreover, while embodiments and/or processes have been described above according to a particular order, that order should not be interpreted as limiting.
• As stated above, the methods and/or structures disclosed herein are not limited to use in association with a micromachined mechanical structure that includes a capacitive transducer to convert vibrational energy to electrical energy. Moreover, some aspects and/or embodiments may employ one or more of the structures and/or methods disclosed herein to supply, store and/or trap electrical charge without one or more of the other structures and/or methods disclosed herein. An “energy harvesting device” may be any type of energy harvesting device. In this regard, energy harvesting devices are not limited to vibrational energy to electrical energy converters. Other sources of environmental energy include but are not limited to temperature and stress (e.g., pressure).
• As stated above, a mechanical structure may have any configuration. Moreover, a mechanical structure may be, for example, a whole mechanical structure, a portion of a mechanical structure and/or a mechanical structure that together with one or more other mechanical structures forms a whole mechanical structure, element and/or assembly.
• As used herein, the term “portion” includes, but is not limited to, a part of an integral structure and/or a separate part or parts that together with one or more other parts forms a whole element or assembly. For example, some mechanical structures may be of single piece construction or may be formed of two or more separate pieces. If the mechanical structure is of a single piece construction, the single piece may have one or more portions (i.e., any number of portions). Moreover, if a single piece has more than one portion, there may or may not be any type of demarcation between the portions. If the mechanical structure is of separate piece construction, each piece may be referred to as a portion. In addition, each of such separate pieces may itself have one or more portions. A group of separate pieces that collectively represent part of a mechanical structure may also be referred to collectively as a portion. If the mechanical structure is of separate piece construction, each piece may or may not physically contact one or more of the other pieces.
• An electrode may also have any configuration (e.g., size, shape and orientation). For example, electrodes may each be rectangular (or generally rectangular) and similar to one another, but are not limited to such. Further, an electrode may include one or more fixed (e.g., stationary) mechanical structures, one or more movable mechanical structures and/or any combination thereof.
• Further, unless otherwise stated, terms such as, for example, “in response to” and “based on” mean “in response at least to” and “based at least on”, respectively, so as not to preclude being responsive to and/or based on, more than one thing. Moreover, the term “coupled to” includes connected directly to and connected indirectly to (i.e., through one or more elements). In addition, as used herein, terms such as, for example, “supply to” and “power” mean “supply directly or indirectly to” and “power directly or indirectly”, respectively, so as not to preclude supplying and/or powering through something else.
• Further, unless specified otherwise, the term “depositing” and other forms (i.e., deposit, deposition and deposited) in the claims, means, among other things, depositing, creating, forming and/or growing a layer of material using, for example, a reactor (for example, an epitaxial, a sputtering or a CVD-based reactor (for example, APCVD, LPCVD, or PECVD). Further, in the claims, the term “contact” means a conductive region, partially or wholly disposed outside the chamber, for example, a contact area and/or contact via.
• Note that, unless stated otherwise, terms such as, for example, “comprises”, “has”, “includes”, and all forms thereof, are considered open-ended, so as not to preclude additional elements and/or features.
• In addition, unless stated otherwise, terms such as, for example, “a”, “one”, “first”, are considered open-ended, and do not mean “only a”, “only one” and “only a first”, respectively.
• It should be further noted that while the present inventions have been described in the context of microelectromechanical systems including micromechanical structures or elements, the present inventions are not limited in this regard. Rather, the inventions described herein are applicable to other electromechanical systems including, for example, nanoelectromechanical systems. Thus, the present inventions are pertinent to electromechanical systems, for example, gyroscopes, resonators, temperatures sensors and/or accelerometers, made in accordance with fabrication techniques, such as lithographic and other precision fabrication techniques, which reduce mechanical components to a scale that is generally comparable to, and/or smaller than, microelectronics.
• In that regard, unless specified otherwise, the term “micromechanical structure”, as used hereinafter and in the claims, includes, micromechanical structures, nanomechanical structures and combinations thereof. Indeed, any MEMS structure that is encapsulated is within the scope of the present invention.
• Finally, as mentioned above, all of the embodiments of the present invention described and illustrated herein may be implemented in the embodiments of Microelectromechanical Systems and Method of Encapsulating Patent Application Publication and/or Microelectromechanical Systems Having Trench Isolated Contacts Patent and/or Anchors for Microelectromechanical Systems Patent. For the sake of brevity, those permutations and combinations will not be repeated but are incorporated by reference herein.
• In addition, while various embodiments have been described, such description should not be interpreted in a limiting sense. Other embodiments, which may be different from and/or similar to, the embodiments described herein, will be apparent from the description, illustrations and/or claims set forth below. Further, although various features, attributes and advantages have been described and/or are apparent in light thereof, it should be understood that such features, attributes and advantages are not required except where stated otherwise.

Claims (5)

1-34. (canceled)

35. A method for use in association with an electromechanical device having a mechanical structure, the method comprising:

depositing a sacrificial layer over the mechanical structure;

depositing a first encapsulation layer over the sacrificial layer;

forming at least one vent through the first encapsulation layer to allow removal of at least a portion of the sacrificial layer;

removing at least a portion of the sacrificial layer to form the chamber;

depositing a second encapsulation layer over or in the vent to seal the chamber;

supplying electrical charge to at least one portion of the mechanical structure; and

storing at least a portion of the electrical charge on the at least one portion of the mechanical structure after depositing the second encapsulation layer and for a period of at least one day.

36. The method ofclaim 35, wherein the first encapsulation layer comprises a polycrystalline silicon, amorphous silicon, germanium, silicon/germanium or gallium arsenide.

37. The method ofclaim 35, wherein the second encapsulation layer comprises polycrystalline silicon, amorphous silicon, silicon carbide, silicon/germanium, germanium, or gallium arsenide.

38-39. (canceled)

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