Disclosure of Invention
The invention aims to provide a manufacturing method of an MEMS device, which aims to solve the problems of more polymers and polymer residues in a process cavity generated in an etching process.
In order to solve the above technical problems, the present invention provides a method for manufacturing a MEMS device, including:
providing a semiconductor substrate;
sequentially forming a first adhesive layer, a metal layer and a second adhesive layer on the semiconductor substrate;
forming an opening in the second adhesive layer, the opening extending through the metal layer to expose a portion of the first adhesive layer;
removing the exposed first adhesive layer and the remaining second adhesive layer;
and forming a dielectric layer, wherein the dielectric layer fills the opening and extends to cover the surface of the metal layer.
Optionally, in the method for manufacturing a MEMS device, the method for forming an opening in the adhesive layer includes:
forming a patterned photoresist layer on the second adhesive layer, the patterned photoresist layer exposing a portion of the second adhesive layer;
etching the exposed second bonding layer and the metal layer by taking the patterned photoresist layer as a mask to form the opening; and etching the exposed second bonding layer and the metal layer through a dry etching process.
Optionally, in the method for manufacturing a MEMS device, the exposed first adhesive layer is removed by dry etching and/or wet etching.
Optionally, in the method for manufacturing a MEMS device, the first adhesion layer includes a first titanium layer and a first titanium nitride layer covering the first titanium layer.
Optionally, in the method for manufacturing a MEMS device, the second adhesion layer includes a second titanium layer and a second titanium nitride layer covering the second titanium layer.
Optionally, in the method for manufacturing a MEMS device, the dielectric layer includes an oxide layer and a nitride layer covering the oxide layer.
Optionally, in the method for manufacturing a MEMS device, the thickness of the oxide layer is 500nm to 1000nm.
Optionally, in the method for manufacturing a MEMS device, the thickness of the nitride layer is 100nm to 400nm.
Optionally, in the method for manufacturing a MEMS device, the number of the openings is at least two, and the two openings isolate the metal layer into a first portion, a second portion and a third portion.
Optionally, in the method for manufacturing a MEMS device, after forming the dielectric layer, the method for manufacturing a MEMS device further includes:
removing the dielectric layer on the surface of the metal layer to expose the metal layer;
a bonding layer, a connection structure and a liner structure are formed, the bonding layer having a first portion of the metal layer, the connection structure overlying a second portion of the metal layer, and the liner structure overlying a third portion of the metal layer.
In the manufacturing method of the MEMS device provided by the invention, an opening is formed in the second bonding layer, and extends through the metal layer so as to expose part of the first bonding layer; then, removing the exposed first adhesive layer and the remaining second adhesive layer; and then, forming a dielectric layer, wherein the dielectric layer fills the opening and extends to cover the surface of the second metal layer. After forming the opening in the second bonding layer, the dielectric layer is formed, and the second bonding layer, part of the metal layer and part of the first bonding layer are removed when the opening is formed, so that the second bonding layer can be prevented from being etched when the dielectric layer is etched later, the generation of polymers can be reduced, the polymers are prevented from remaining in the process cavity, and the problems that more polymers are generated during the etching process and the polymers remain in the process cavity are solved.
Detailed Description
The method for manufacturing the MEMS device according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
Fig. 1 is a schematic flow chart of a method for manufacturing a MEMS device according to an embodiment of the invention. As shown in fig. 1, the present invention provides a method for manufacturing a MEMS device, comprising:
step S1: providing a semiconductor substrate;
step S2: sequentially forming a first adhesive layer, a metal layer and a second adhesive layer on the semiconductor substrate;
step S3: forming an opening in the second adhesive layer, the opening extending through the metal layer to expose a portion of the first adhesive layer;
step S4: removing the exposed first adhesive layer and the remaining second adhesive layer
Step S5: and forming a dielectric layer, wherein the dielectric layer fills the opening and extends to cover the surface of the second metal layer.
Next, referring to fig. 2 to 5, fig. 2 to 5 are schematic structural views formed in the method for manufacturing the MEMS device according to the embodiment of the invention. As shown in fig. 2, in step S1, a semiconductor substrate 100 is provided, on which the semiconductor substrate 100 may be a semiconductor substrate 100 formed with various active devices and interconnection structures, doped regions and/or isolation structures (not shown), and the semiconductor substrate 100 may be at least one of the following mentioned materials: silicon, silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-germanium-on-insulator (SSiGeOI), silicon-germanium-on-insulator (SiGeOI), and the like. An isolation structure may be formed in the semiconductor substrate 100, which is a Shallow Trench Isolation (STI) structure or a local oxidation of silicon (LOCOS) isolation structure.
In step S2, a first adhesive layer 110, a metal layer 120, and a second adhesive layer 140 are sequentially formed on the semiconductor substrate 100; specifically, the first adhesion layer 110 includes a first titanium layer 111 and a first titanium nitride layer 112 covering the first titanium layer 111. The first adhesive layer 110 may be formed on the surface of the semiconductor substrate 100 using a chemical vapor deposition process or a sputter deposition process. Then, a metal layer 120 is formed, the metal layer 120 covering the first adhesion layer 110, specifically, the metal layer 120 covering the first titanium nitride layer 112. The metal layer 120 may be Cu (copper), al (aluminum), W (tungsten), or Ag (silver), and the metal layer 120 may be a top metal layer on the semiconductor substrate 100.
Specifically, the method for forming the metal layer 120 includes: an interlayer dielectric layer is deposited on the first adhesive layer 110. Preferably, the interlayer dielectric layer may be formed of a low-k dielectric material, such as fluorosilicone glass, silicon oxide, a carbon-containing material, a porous material, and the like. A bottom antireflective layer (BARC) and a patterned photoresist layer defining a trench pattern are then sequentially formed over the interlayer dielectric layer. And etching the interlayer dielectric layer by using the bottom anti-reflection layer and the patterned photoresist layer as masks to form a groove, wherein the groove can be a common groove with common shape, such as a common groove with the same critical dimension of an upper opening and a lower opening. Alternatively, a trench with a wide upper part and a narrow lower part may be selected, and the trench is not limited to a certain shape and may be set as required. The trenches are then filled with a conductive material, which may be aluminum but is not limited thereto, and other materials known to those skilled in the art, such as copper, tungsten, etc., may be used and planarized to form the metal layer 120. Next, the second adhesion layer 140 is formed on the metal layer 120, and the second adhesion layer 140 includes a second titanium layer 141 and a second titanium nitride layer 142 covering the second titanium layer 141.
In step S3, as shown in fig. 3, an opening is formed in the second adhesive layer 140, and the opening extends through the metal layer 120 to expose a portion of the first adhesive layer 110. Specifically, the number of the openings is at least two, for example, a first opening 130 and a second opening 131, and the first opening 130 and the second opening 130 may isolate the metal layer 120 into a plurality of portions. Specifically, the first opening and the second opening isolate the metal layer 120 into a first portion 121, a second portion 122, and a third portion 123. I.e. the metal layer 120 comprises a first portion 121, a second portion 122 and a third portion 123.
Specifically, the method for forming an opening in the second adhesive layer 140, where the opening extends through the metal layer includes: the method of forming an opening in the adhesive layer includes: forming a patterned photoresist layer on the second adhesive layer 140, the patterned photoresist layer exposing a portion of the second adhesive layer 140; etching the exposed second adhesive layer 140 and the metal layer 120 with the patterned photoresist layer as a mask, and stopping etching on the first adhesive layer 110 to form the opening; that is, only the second adhesive layer 140 and the metal layer 120 are etched when the opening is formed, thereby reducing the etching amount to reduce the generation of polymer. Here, the second adhesive layer 140 may serve as an anti-reflection layer during etching, thereby improving the etching effect on the metal layer 120. The patterned photoresist layer and the anti-reflective layer are then removed to expose the remaining second adhesion layer 140.
Further, the exposed second adhesion layer 140 and the metal layer 120 are etched by a dry etching process. The dry etching gas may include a fluorine-containing gas and an auxiliary gas, the fluorine-containing gas may be one or more of SiF4, NF3, SF6, CF4, CF3I, CHF3, CH3F, CH2F2, C2F6, C3F8, and C4F8, and the auxiliary gas may be one or more of O2, N2, CO2, H2, and Ar.
The fluorine-containing gas is used as the gas for dry etching, so that the free radical polymerization speed of the dissociated etching gas is smaller than the pumping speed of the byproducts, polymer deposition in the etching cavity is less in the etching process, the environment in the etching cavity is cleaner, and the polymer adsorbed in the process cavity can be reduced.
In step S4, as shown in fig. 4, the exposed first adhesive layer 110 and the remaining second adhesive layer 140 are removed, thereby exposing the metal layer 120; specifically, the exposed first adhesive layer 110 and the remaining second adhesive layer 140 may be removed by dry etching and/or wet etching. Next, a cleaning process may be performed on the semiconductor substrate 100 to remove the polymer generated during the dry etching and/or wet etching, and to completely remove the remaining photoresist layer and the anti-reflection layer.
As shown in fig. 5, in step S5, a dielectric layer 150 is formed, and the dielectric layer 150 fills the opening and extends to cover the surface of the metal layer 120. Specifically, the dielectric layer 150 includes an oxide layer 151 and a nitride layer 150 covering the oxide layer. Wherein the thickness of the oxide layer 151 is 500nm-1000nm, and the thickness of the nitride layer 150 is 100nm-400nm. Since the second adhesive layer 140 is removed in step S4, it is not necessary to etch the second adhesive layer 140 when the dielectric layer 150 is etched later, and thus, during etching, the generation of polymer can be avoided or reduced, and polymer residue in the process chamber can be further avoided.
After forming the dielectric layer 150, the method for manufacturing the MEMS device further includes: etching the dielectric layer 150 to expose the metal layer 120; then, a bonding layer covering the first portion 121 of the metal layer 120, a connection structure covering the second portion 122 of the metal layer 120, and a pad structure covering the third portion 123 of the metal layer 120 are formed. The bonding layer may be used for bonding the MEMS device with other substrates in a subsequent process, the connection structure may be used for electrical connection with an external circuit, and the pad structure may be used for a terminal of the MEMS device. Specifically, the bonding layer, the connection structure and the pad structure may be made of metal. Since the second adhesive layer 140 is removed, etching of the second adhesive layer 140 can be avoided when the metal layer 120 is exposed, whereby generation of polymer can be reduced.
In addition, in the prior art, since the pad structure needs to be connected to the metal layer 120 and an adhesive layer is generally formed on the metal layer 120, two etching methods are required to expose the metal layer 120, thereby forming a pad structure on the exposed metal layer 120, and in this embodiment, since the second adhesive layer 140 is removed, the metal layer 120 may be exposed by one etching method of the dielectric layer 150, thereby forming a pad structure on the exposed metal layer 120, thereby simplifying the process and reducing the generation of polymers.
In summary, in the method for manufacturing a MEMS device provided by the present invention, an opening is formed in the second adhesive layer, the opening extending through the metal layer to expose a portion of the first adhesive layer; then, removing the exposed first adhesive layer and the remaining second adhesive layer; and then, forming a dielectric layer, wherein the dielectric layer fills the opening and extends to cover the surface of the second metal layer. After forming the opening in the second bonding layer, the dielectric layer is formed, and the second bonding layer, part of the metal layer and part of the first bonding layer are removed when the opening is formed, so that the second bonding layer can be prevented from being etched when the dielectric layer is etched later, the generation of polymers can be reduced, the polymers are prevented from remaining in the process cavity, and the problems that more polymers are generated during the etching process and the polymers remain in the process cavity are solved.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.