USRE37546E1 - Reactor and method of processing a semiconductor substrate - Google Patents

Abstract

A reactor for processing a substrate includes a first housing defining a processing chamber and supporting a light source and a second housing rotatably supported in the first housing and adapted to rotatably support the substrate in the processing chamber. A heater for heating the substrate is supported by the first housing and is enclosed in the second housing. The reactor further includes at least one gas injector for injecting at least one gas into the processing chamber onto a discrete area of the substrate and a photon density sensor extending into the first housing for measuring the temperature of the substrate. The photon density sensor is adapted to move between a first position wherein the photon density sensor is directed to the light source and a second position wherein the photon density sensor is positioned for directing toward the substrate. Preferably, the communication cables comprise optical communication cables, for example sapphire or quartz communication cables. A method of processing a semiconductor substrate includes supporting the substrate in a sealed processing chamber. The substrate is rotated and heated in the processing chamber in which at least one reactant gas is injected. A photon density sensor for measuring the temperature of the substrate is positioned in the processing chamber and is first directed to a light, which is provided in the chamber for measuring the incident photon density from the light and then repositioned to direct the photon density sensor to the substrate to measure the reflection of the light off the substrate. The incident photon density is compared to the reflected light to calculate the substrate temperature.

Description

BACKGROUND AND TECHNICAL FIELD OF THE INVENTION

The present invention relates to a processing reactor and, more particularly to a processing reactor for the thermal processing and chemical deposition of thin film applications on a substrate, such as semiconductor wafer, in which the temperature of the substrate can be accurately monitored and the injection of gas into the chamber can be controlled to provide better control of the substrate processing.

In semiconductor fabrication, semiconductor substrates are heated during various temperature activated processes for example, during film deposition, oxide growth, etching, and thermal annealing. The control of deposition and annealing processes depends on the control of the gas flow and pressure and the wafer temperature. When heating a substrate, it is desirable to heat the substrate in a uniform manner so that all the regions of the substrate are heated to the same temperature. Uniform temperatures in the substrate provide uniform process variables on the substrate; for instance in film deposition, if the temperature in one region of the substrate varies from another region, the thickness of the deposition in these regions may not be equal. Moreover, the adhesion of the deposition to the substrate may vary as well. Furthermore, if the temperature in one region of the substrate is higher or lower than the temperature in another region of the substrate, a temperature gradient within the substrate material is formed. This temperature gradient produces thermal moments in the substrates which in turn induce radial local thermal stresses in the substrate. These local thermal stresses can reduce the substrate's strength and, furthermore, damage the substrate. Therefore, knowing the temperature of the wafer is important in determining the thermal diffusion depths of surface implanted dopants, the deposited film thickness, and the material constitution quality and annealed or reflowed characteristics.

Various methods have been developed for measuring the temperature of a substrate during processing in order to improve the control of the various processes. Direct methods, which include the use of contact probes, such as thermocouples or resistance wire thermometers, are generally not suitable for substrate processing because direct contact between the probes and the substrate contaminates the device structure. More typically, indirect measuring methods are used, such as the use of preheated platforms that are calibrated prior to processing. However, this method is not typically accurate. In some applications, the temperature of the back side of the substrate is calibrated or monitored, but such methods also lead to significant errors due to the large variances between the back side and device side surface characteristics that lead to different substrate temperatures. The patterns of the specific devices being processed, the type of material being deposited or annealed, the degree of the roughness of the surface, and the operating temperature all affect the characteristics of the substrate surface and define what is known as the surface emissivity of the substrate.

In U.S. Pat. No. 5,310,260 to Schietinger et al. a non-contact temperature measuring device is disclosed. The device includes two sapphire optical fibre probes, with one of the probes directed to the lamp source providing the heat to the wafer and the other probe directed to the wafer itself. Each fiber probe sends its respective signal to a measuring instrument which converts the photon density measured by the probe to an electrical current. The ratio of the two signals provides a measure of the surface reflectivity, which approximates the total hemispherical reflectivity. However, this method can only be used with an AC source lamp and when the lamp shines directly on the wafer. Since two optical fiber probes must be used in order to implement this technique, the characteristics of each probe must be accurately detailed in order to obtain accurate emissivity measurements. In the event that one of the probes must be replaced, a total system re-calibration is required. Furthermore, this method cannot be used in chambers in which thin films are deposited, etched, or sputtered since the thin films will also deposit on the optical fiber photon density sensors and drastically alter the results and render the measurement method inoperative. Moreover, the optical fiber sensors are always directed at one fixed area of the wafer. Since different parts of the wafer may have different device patterns and, therefore, may have different local emissivities, the temperature measurement and control would be limited in value as it would represent the emissivity information only for that specific area rather than the average surface topology of the substrate.

In addition to temperature uniformity, the uniformity of film deposition is affected by uniformity of the delivery of the process gas. Good process uniformity usually requires adjustments and optimizations for both the wafer temperature uniformity and the gas flow pattern of the process gas. In most conventional chambers or reactors, the reactant gas is delivered through a single port, which injects gas into the chamber above the wafer. Due to the geometry of the wafer, the resulting deposition of the gas onto the wafer is not uniform.

More recently, shower-like gas injection systems have been developed in which separate gases are injected in a shower-like pattern over the entire substrate area. However, such gas delivery systems fill the entire chamber volume and, thus, deposit films on the substrate as well as the chamber walls. Consequently, these gas delivery systems preclude the use of any optical instruments for non-contact temperature measurement and in-situ film methodology.

Consequently, there is a need for a processing reactor which can deliver heat to a substrate in a uniform manner and can accurately monitor the temperature of the substrate during processing and adjust the profile of the applied heat as needed to achieve optimal processing of the substrate. Furthermore, there is a need for a processing reactor which can deliver and direct the flow of gas to the substrate during processing so that the substrate receives a uniform deposition of thin film of the process gas or gases in a discrete area on the substrate.

SUMMARY OF THE INVENTION

One form of the invention provides a reactor having a processing chamber with an emissivity measuring device and improved gas injection system. The emissivity measuring device measures the photon density from a light source, which is housed in the processing chamber, and the reflected photon density off a substrate, which is processed in the processing chamber. These measurements are then used to determine the emissivity and, ultimately, the temperature of the substrate with a high degree of accuracy. The emissivity measuring device includes a communications cable which includes a photon or emissivity sensor that is positioned in the processing chamber. The photon density sensor is adapted to move between a first position wherein the photon density sensor is directed to the light source for measuring the incident photon density of the light and a second position wherein the photon density sensor is directed toward the substrate for measuring the reflected photon density off the substrate. The gas injection system is adapted to inject and direct at least one gas onto a discrete area of the substrate. The reactor is, therefore, particularly suitable for use in a semiconductor fabrication environment where the control of heating and injection of gas must be maintained in order to produce uniform process variables during the fabrication of semiconductor devices.

In one aspect, the emissivity measuring device comprises first and second communication cables. The first communication cable includes the photon density sensor and is in communication with the second cable for sending signals from the photon density sensor to a processor. Preferably, the first and second communication cables comprise optical communication cables. For example, the first communication cable may comprise a sapphire optical communication cable, and the second communication cable may comprise a quartz optical communication cable. In further aspects, the first and second communications cables are interconnected by a slip connection so that the first communication cable can be rotated between the first and second positions by a driver, for example a motor.

In another form of the invention, a reactor for processing a substrate includes a first housing, which defines a processing chamber and supports a light source. A second housing is rotatably supported in the first housing and is adapted to rotatably support the substrate in the processing chamber. A heater for heating the substrate is supported by the first housing and is enclosed in the second housing. A photon density sensor extends into the first housing for measuring the emissivity of the substrate, which is adapted to move between a first position wherein the photon density sensor is directed to the light source and a second position wherein the photon density sensor is positioned for directing toward the substrate. The reactor further includes a plurality of gas injectors, the gas injectors being grouped into at least two groups of gas injectors, with each group of gas injectors being adapted to inject at least one gas into the processing chamber of the reactor onto a discrete area of the substrate.

In one aspect, each group of injectors is adapted to selectively deliver at least one reactant gas and an inert gas. In another aspect, each group of gas injectors is adapted to be independently controlled whereby flow of gas through each group of gas injectors can be independently adjusted. In yet another aspect, the gas injectors in each group of gas injectors may be arranged in a uniform pattern for directing a uniform flow of a gas toward the substrate. The reactor also preferably includes an exhaust manifold for removing unreacted gas from the processing chamber.

In yet further aspects, the gas injectors are arranged in pattern having a greater concentration of gas injectors in a peripheral region and a smaller concentration of gas injectors in a central region of the substrate whereby the gas injected by the gas injectors produces a uniform deposition on the substrate.

In yet another form of the invention, a method of processing a semiconductor substrate includes supporting the substrate in a sealed processing chamber. The substrate is rotated and heated in the processing chamber in which at least one reactant gas is injected. A photon density sensor for measuring the emissivity of the substrate is positioned in the processing chamber and is first directed to a light, which is provided in the chamber, for measuring the incident photon density from the light and then repositioned to direct the photon density sensor to the substrate to measure the reflected photon density off the substrate. The incident photon density is compared to the reflected photon density to calculate the substrate temperature.

As will be understood, the reactor of the present invention provides numerous advantages over prior known reactors. The reactor provides a single substrate photon density sensor which can be used to accurately determine the temperature of the substrate during processing. The single photon density sensor eliminates the need for recalibration and complex calculations detailing the characteristics of each sensor associated with temperature measuring devices having two sensors. Moreover, the reactor provides a gas injection system which directs one or more reactant gases to the substrate during processing in a controlled manner and directs the gas or gases to discrete regions of the substrate so that emissivity measurements and temperature calculations can be performed in the processing chamber during the injection of the gas or gases without impairment from undesirable film depositions on the emissivity measurement devices.

These and other objects, advantages, purposes and features of the invention will be apparent to one skilled in the art from a study of the following description taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a chemical vapor deposition chamber of the present invention;

FIG. 2 is a schematic sectional view taken along line II—II of FIG. 1;

FIG. 3 is an enlarged view taken along section lines III—III of FIG. 2 illustrating the gas injection system;

FIG. 4 is a top plan view of the chamber cover;

FIG. 5 is a bottom plan view of the chamber cover; and

FIG. 6 is a schematic representation of an emissivity measurement system cooperating with the chemical vapor deposition chamber of FIG.1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and particular to FIGS. 1 and 2, a reactor for processing semiconductor substrates is generally indicated by the numeral10. In the illustrated embodiment,reactor10 comprises a single wafer processing reactor that is suitable for performing various fabrication processes on asemiconductor substrate12, such as a semi-conductor wafer.Reactor10 is particularly suitable for thermal processing of a semiconductor wafer. Such thermal processes include thermal annealing of a semiconductor wafer and thermal reflow of boro-phosphorous gasses, and chemical vapor deposition of thin film applications, such as high temperature oxide, low temperature oxide, high temperature nitride, doped and undoped polysilicon, silicon epitaxial and tungsten metal and tungsten silicide films, in the fabrication of a semiconductor device. The control of these processes depends on the control of gas flow, gas pressure, and wafer temperature. As will be described in more detail,reactor10 includes aheater assembly14, which delivers heat to thesubstrate12 in a uniform manner, agas injection assembly34, which selectively delivers and directs gas to a discrete region of the substrate in a uniform and controlled manner, and anemissivity measurement assembly60, which permits continuous emissivity measurement of the average surface area of the device side of the substrate during processing so that the amount and/or the profile of the heat being delivered to the substrate during processing may be adjusted.

As best seen in FIG. 2,reactor10 includes aheater assembly14, which is enclosed in aheater housing16.Heater assembly14 is designed to deliver radiant heat tosubstrate12 in a manner such that the temperature in the substrate is substantially uniform. In a preferred form,heater assembly14 includes an array of heating elements such as linear tungsten-halogen lamps (not shown), which emit peak radiation at 0.95 microns and are layered to form a plurality of heating zones, which provide a concentrated heating profile with a greater amount of heat being applied to the outer perimeter of the substrate than the center of the substrate. For further details ofheater assembly14, reference is made to pending U.S. patent application entitled RAPID THERMAL PROCESSING HEATER TECHNOLOGY AND METHOD OF USE, filed on Dec. 4, 1996. Ser. No. 08/759,559, which is incorporated herein by reference in its entirety. It should be understood that other heaters may be used inreactor10, preferably heaters which deliver heat to substrate in a substantially uniform manner.

Heater assembly14 is enclosed inheater housing16, which is mounted on arotatable base18.Heater housing16 is made from a suitable material, such as a ceramic, graphite or, more preferably, silicon graphite coated graphite, or the like.Heater assembly14,heater housing16, androtatable base18 are enclosed and vacuum sealed in an outer,reactor housing20 and are supported on abase wall22 ofreactor housing20.Reactor housing20 may be formed from a variety of metal materials. For example, aluminum is suitable in some applications, whereas stainless steel is more suitable in others. The choice of material is driven by the type of chemicals used during the deposition process and their reactivity with respect to the metal of choice, as is understood by those persons skilled in the art. The chamber walls are typically water cooled to approximately 45-75 degrees Fahrenheit by a conventional recirculating chilled water flow system, which is commonly known in the art.

Referring to FIGS. 2 and 3,base18 andhousing16 are rotatably supported onbase wall22 of housing and are preferably rotated using a conventional magnetically coupleddrive mechanism23, or other suitable driving device which can impart rotation to base18 through a vacuum seal. The revolutions per minute (rpm) ofbase18 andhousing16 may be preset, for example preferably in a range of 5 to 60 rpm depending on the specific process, again as is understood by those persons skilled in the art.

As best seen in FIG. 1,reactor housing20 includes a cylindricalouter wall24 and acover26 which extends over cylindricalouter wall24.Substrate12 is supported inreactor housing20 on aplatform28, which is made from a suitable material, such as silicon carbide coated graphite, quartz, pure silicon carbide, alumina, zirconia, aluminum, steel, or the like, and is oriented with its device side12a directed towardcover26. For details of a preferred embodiment ofplatform28, reference is made to pending U.S. patent application entitled A SUBSTRATE PLATFORM FOR A SEMICONDUCTOR SUBSTRATE DURING RAPID HIGH TEMPERATURE PROCESSING AND METHOD OF SUPPORTING A SUBSTRATE filed on Aug. 15, 1997, Ser. No. 08/912,242, by Imad Mahawili, which is herein incorporated by reference in its entirety.Platform28 is seated and supported in a recess or central opening16a provided in a top wall27 ofhousing16 and spaced fromcover26 and substantially extends over and completely cover opening16a. Consequently,heater assembly14 is completely enclosed byheater housing16 andplatform28, which when placed on top of thehousing16, completes the enclosure ofheater assembly14.Platform28 can accommodate various substrate sizes and, in particular, can accommodate substrates with 150, 200 and 300 mm diameters. The space betweenplatform28 and the lower surface26a ofcover26 defines an evacuatedprocess chamber30, which is evacuated through the vacuum exhaust parts placed in agas injector assembly34. Preferably,substrate12 is introduced into evacuatedchamber30 through achamber valve32 and is placed onplatform28 by a conventional wafer transport device (not shown), such as an automated transport robot.

Referring to FIGS. 4 and 5,reactor10 further includesgas injection manifold34 which injects one or more gases onto a localized or discrete region of the substrate surface wherein thin film deposition takes place.Gas injection manifold34 is positioned incover26 and includes a plurality of reactivegas injection segments36,38, and40, an inertgas injection ring41, and an exhaust manifold44.Injection ring41 injects an inert gas, preferably nitrogen or the like, intoprocessing chamber30 and directs the inert gas to the perimeter of the substrate to form a gas barrier so that the reactive gases injected throughgas injection segments36,38, and40 are confined to the area of the substrate directly below therespective segments36,38, and40 due to the placement of vacuum exhaust manifold44 adjacentgas injection segments36,38, and40. As best seen in FIG. 5,gas injection segments36,38, and40 are aligned in a central region ofcover26 to inject one or more gases, reactive and inert gases, intochamber30. Exhaust manifold44 extends along and adjacentgas injection segments36,38, and40 so that gases directed ontosubstrate12 are confined to a discrete area across the substrate, which preferably extends from one side or edge of the substrate to an opposed side or edge ofsubstrate12. It should be understood that gases injected bygas injection segments36,38, and40 are directed in thegeneral direction substrate12 and any stray gas molecules which migrate near the region under exhaust manifold44 will be exhausted from processingchamber30. Therefore, the gases introduced bygas injection segments36,38, and40 are confined to a discrete volume of processingchamber30 and to a discrete area ofsubstrate12.

Eachgas injection segment36,38,40 includes a plurality of channels36a,36b,36c,36d,38a,38b,38c,38d,40a,40b,40c, and40d, respectively, which are arranged in a parallel adjacent relationship. Each channel36a,36b,36c,36d,38a,38b,38c,38d40a,40b,40c, and40d includes a plurality of injectors ororifices42.Orifices42 may be arranged in a uniform manner to provide the same flow rate of gas across width ofsubstrate12. Alternatively, one or more channels may includeorifices42 that are arranged in a non-uniform pattern to vary the profile of the gas flow across the substrate. Preferably, the profile of the flow of the gas is adjusted to direct less gas to the center of the substrate than to the regions toward the perimeter of the substrate. For example, channels38a-38d, which are generally aligned with the central portion of the substrate, may include one density or concentration of spaced orifices, and channels36a-36d and40a-40d, which are generally aligned along the peripheral portions of the substrate, may include a higher density or concentration oforifices42 than channels38a-38d. In this manner, the flow of gas from the various groups oforifices42 has a flow profile that varies across the substrate so that the regions over the central region and the peripheral region of the substrate are treated with the same density of gas to achieve a more uniform film deposition on the substrate. It should be understood that the number of orifices and the spacing betweenorifices42 may be individually adjusted to prove a more uniform flow or to direct more gas to one area of the substrate than another where different devices are being fabricated.

Furthermore, eachorifice42/ channel36a,36b,36c,36d,38a,38b,38c,38d40a,40b,40c, and40d and/orsegments36,38, and40 may be coupled to a valve or regulator (not shown) which may be adjusted using conventional controls to vary the flow of gas from each orifice, channel, or gas injection segment orzone36,38, and40 to adapt the gas flow profile. Furthermore, the controls may adjust the sequence of gas flowing from the orifices, channels, or segments. Moreover, each regulator may be adapted for connection with one or more sources of reactant gases. Depending on the application, the flow through each orifice/ channel/ segment/ may be individually controlled so that they can all turn on together, sequence one segment after another, or sequence the segments randomly with various time intervals between each on/off cycle. Furthermore, as reactive gases are turned off from one segment, an inert gas may be injected into that segment to control the reaction conditions at the surface of the wafer and to prevent any back flow contamination of reactants. The design of a particular duty cycle for each of the segments would, therefore, depend on the thin film process that is being optimized and it would vary from one film to another. Furthermore, each of the respective orifices, channels, orgas injection segments36,38,40 may be associated with an injection of a specific gas. For example,gas injection zones36 and40 may be used to inject gas A whilegas injection zone38 may be used to inject gas B. In this manner, two reactive gases (A and B) may be injected that mix and react on the device side of the substrate. It should be understood by those skilled in the art that a wide variety of gasses can be employed and selectively introduced through theorifices42, for example, hydrogen, argon, tungsten hexaflouride, or the like, to processsubstrate12.

As best seen in FIG. 5,gas injection manifold34 includes exhaust manifold44. As described above, exhaust manifold44 extends aroundsegments36,38, and40 to provide an additional boundary beyond which the reactive gases can not extend. In addition to removing unreacted gases from processingchamber30, exhaust manifold also assists in the prevention of back flow contamination of the reactant gases. In combination withinjection ring41, exhaust manifold44 controls the film deposition onsubstrate12 in a manner which results in localized area of film deposition and, therefore, permits the use of an emissivity measurement system, described below.

Reactor10 further includes a non-contactemissivity measurement system60 for measuring the emissivity and calculating the temperature ofsubstrate12 during the various fabrication processes.Emissivity measurement system60 includes acentral processing unit61 and a pair of fiberoptic communication cables62 and64 which are coupled together and coupled tocentral processing unit61.Fiber optic cable62 preferably comprises a sapphire fiber optic communication cable and extends intocover26 ofreactor housing20 through arigid member66, which provides a vacuum feedthrough toreactor10.Cable62 extends throughmember66 into acavity67 provided incover26, which is positioned aboveplatform28 andsubstrate12.Member66 is preferably a cylindrical drive shaft and, more preferably, a stainless steel cylindrical drive shaft, and is rotatably mounted incover26. Oneend68 offiber optic cable62 is bent or oriented for directing atsubstrate12 andlight source72, as will be more fully explained below, with the photon sensing end ofcable62 forming a fiber optic photon density sensor orprobe70. The second end portion ofcable62 extends throughshaft66 and into afiber optic housing76, which is mounted to an exterior surface ofcylindrical wall24 ofhousing20. Distal end62a ofcable62 is slip attached to a distal end64a of cable64, which preferably comprises a quartz fiber optic communication cable, infiber optic housing76. The other end of fiber optic communication cable64 is then connected toprocessor61. In this manner, whencable62 is rotated,cable62 remains in communication with cable64 andprocessing unit61 through the slip connection between the two communication cables.Processor61 preferably comprises a measuring instrument, for example a Luxtron Model 100, which converts the photon density measured byfiber optic sensor70 into an electrical current, which is displayed byprocessor61.

The position offiber optic sensor70 is changed by adriver80, preferably a motor, which is housed infiber optic housing76 and which is drivingly coupled toshaft66.Motor80 includes adrive shaft81 and adrive wheel82, which engages and rotatesshaft66 about its longitudinal axis66a.Motor80 rotatesshaft66, which imparts rotation tofiber optic cable62, so that the orientation offiber optic sensor70 is moved between a first position wherein thefiber optic sensor70 is directed generally upward towardlight source72 and a second position in which it is directed generally downward tosubstrate12. Therefore, end68 ofcommunication cable62 is preferably oriented at a right angle with respect to the horizontal axis62a ofcommunication cable62. In thismanner sensor70 can detect the photon density emitted fromlight source72 and of the reflected light off substrate.Light source72 preferably comprises a white light source, which emits light at a wavelength so that the wafer optical transmission is minimized, preferably, for example at a 0.95 micron wavelength.Emissivity measurement system60 determines the temperature ofsubstrate12 by comparing of the radiation emitted bysource72 with that of the radiation emitted bysubstrate12.Source72 preferably includes at least one lamp which is a similar construction to the lamps used inheater assembly14, which are described in pending U.S. patent application entitled RAPID THERMAL PROCESSING HEATER TECHNOLOGY AND METHOD OF USE.

Preferably,photon density sensor70 is spaced and, preferably, located radially outward fromgas injection system34 and exhaust manifold44 so that the gas, which is injected intochamber30 and ontosubstrate12, does not interfere with the temperature reading ofemissivity sensor70. Sinceheater assembly14 is completely enclosed by theheater housing16, there is no leakage of light fromheater assembly14 intodeposition chamber30, which could impact the readings taken byemissivity sensor70. This eliminates probe characteristics matching or corrections associated with the conventional temperature measuring devices with two probes. Aftersubstrate12 is placed onplatform28,housing16 andplatform28 are rotated during processing bydrive mechanism23. When the emissivity ofsubstrate12 is to be measured,sensor70 is rotated to viewlight source72 directly abovesubstrate12 andlight source72 is turned on.Sensor70 measures the incident photon density fromlight source72. Whilelight source72 is still on,sensor70 is rotated from its first position to its second position to viewsubstrate12 directly belowlight source72 while it is rotating. In this position,sensor70 measures the reflected photon density off the device side12a ofsubstrate12.Light source72 is then turned off. While still viewingsubstrate12 directly,sensor70 measures the emission of photons fromheated substrate12. This last value is subtracted from the reflected radiation value. According to Plank's law, the energy emitted off a given surface is related to the temperature of the surface to the fourth power. The proportionality constant consists of the product of the Stephen-Boltzmann constant and the surface emissivity. Therefore, the surface emissivity is preferably used when determining the temperature of the surface in non-contact methods. The following equations are used to calculate the total hemispherical reflectivity of device side12a ofsubstrate12 and, subsequently, the emissivity, as given by Kirchoffs law:

Wafer Reflectivity=Reflected Light Intensity/Incident Light Intensity  (1)

Emissivity=(1−Wafer Reflectivity)  (2)

Once the substrate emissivity is calculated, the substrate temperature is then obtained from Plank's equations. This technique is also used when the substrate is hot and, under such application, the base thermal emission from the substrate is subtracted prior to executing the above calculation. Preferably,sensor70 is left in the second position or wafer viewing position and, thus, constantly yields emissivity data everytime source lamp72 is turned on.

Sincesubstrate12 is rotating,sensor70 collects photon density off the device side12a of thesubstrate12 during such rotation and, therefore, measures the reflection from the averaged surface topology of varied device structures that might be lithographed onto the substrate. Furthermore, since the emissivity measurement is performed during the process cycle including thin film deposition process, the instantaneous changes of emissivity are monitored and temperature corrections are performed dynamically and continuously. Once the emissivity is calculated, it is sent into the temperature control segment of the processor21 where the emissivity value is used in the application of the Plank equation.

Reactor10 further includes a plurality of optical fiber temperature measurement probes84, which are fixed to cover26 and constantly collect photon density emitted from device side12a ofsubstrate device12 during all processing conditions. The temperatures measured byprobes84 are sent to the main control computer to compare them to a set temperature and any deviation is computed and transformed into a control current to drive a standard off-the-shelf SCR current relay to deliver the proportional power to each of the lamp zones withinheater assembly14. Preferably,reactor10 includes three probes (84) which are positioned to measure the temperature of different parts of the wafer, which assures temperature uniformity during the processing cycle.

Temperature readings ofsubstrate12 calculated by central processing unit21 are preferably used as input into a control system (not shown) which monitors and controls the output ofheater assembly14. The control system is coupled toheater assembly14 through anelectrical feedthrough86 which extends to thebase wall22 of reactor housing21. In order to maintain the vacuum inreactor10,feedthrough86 is sealed by an O-ring or sealed using other conventional sealing devices or methods.

Aftersemiconductor substrate12 has been processed,substrate12 is raised offplatform28 by a plurality of lifter pins88 which protrude through and liftsubstrate12 offplatform28 for automatic loading and unloading ofsubstrate12 withinreactor10. Lifter pins88 are raised and lowered by magnetically coupledwafer letters90, which are conventionally known in the art.Pins88 are centrally located inhousing16 and project through a central portion of theheater assembly14 and through a central portion ofplatform28. Similarly, to maintain the vacuum inchamber30. Lifter pins88 extend through O-ring seals provided in thebase wall22 ofhousing20.

In preferred form, at least threelifter pins88 are provided. In the most preferred form, fourlifter pins88 are provided, andplatform28 includes a corresponding number of openings to enablelifter pins88 to protrude through and liftsubstrate12 offplatform28 for automatic loading and unloading ofsubstrate12. It can be appreciated that lifter pins88 can only be operated when housing is positioned so that the openings inplatform28 are aligned with lifter pins88, for example in a “HOME” position.

For the purposes of the following description, the terms “up” or “down” and derivatives or equivalents thereof shall relate to the invention as oriented in FIGS. 1 to6. It is understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also understood that the specific devices and methods illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered Limiting unless the claims expressly state otherwise.

Accordingly, the present invention provides a reactor chamber which heats a substrate in a uniform manner and accurately measures the emissivity and calculates the temperature of the substrate during processing using a non-contact photon density measuring device and adjusts the profile of the applied heat as needed to achieve optimal processing of the substrate. Furthermore, the reactor chamber delivers and controls the flow of gas to the substrate during processing so that the substrate receives a uniform deposition of thin film of the process gas or gases in a discrete area on the substrate, which enables the use of a non-contact emissivity measurement system.

While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow.

Claims (61)

We claim:

1. A reactor for processing a substrate, said reactor comprising:

a housing defining a processing chamber;

a light source supported in said housing;

a heater positioned in said housing, said heater being adapted to heat the substrate;

at least one gas injector adapted to inject at least one gas into said processing chamber onto a discrete area of the substrate; and

a photon density sensor extending into said housing, said photon density sensor being adapted to measure the emissivity of the substrate and to move between a first position wherein said photon density sensor is directed to said light source and a second position wherein said photon density sensor is positioned for directing toward the substrate.

2. The reactor according toclaim 1, further comprising first and second communication cables, said first communication cable including said photon density sensor and being in communication with said second cable and being adapted to send signals from said photon density sensor to a processor.

3. The reactor according toclaim 2, wherein said first and second communications cable comprise optical communication cables.

4. The reactor according toclaim 3, wherein said first communication cable comprises a sapphire optical communication cable.

5. The reactor according toclaim 3, wherein said second communication cable comprises a quartz optical communication cable.

6. The reactor according toclaim 3, wherein said first and second communications cables are interconnected by a slip connection.

7. The reactor according toclaim 6, wherein said first communication cable is rotated between said first and second positions by a driver.

8. The reactor according toclaim 7, wherein said driver comprises a motor.

9. The reactor according toclaim 7, wherein at least a portion of said first communication cable is housed in a rigid member, said driver drivingly engaging said rigid member to rotate said communication cable between said first position and said second position.

10. The reactor according toclaim 9, wherein said rigid member comprises a cylindrical shaft.

11. The reactor according toclaim 2, wherein said first communications cable includes an angled portion, said photon density sensor being defined on a distal end of said angle portion.

12. The reactor according toclaim 1, wherein said housing includes a cover, said photon density sensor being supported by said cover.

13. The reactor according toclaim 12, wherein said photon density sensor comprises an optic communication fiber.

14. The reactor according toclaim 13, wherein said optic communication fiber comprises a sapphire optic communication fiber.

15. The reactor according toclaim 1, further comprising a second housing, said second housing being rotatably supported in said housing defining a processing chamber and being adapted to rotatably support the substrate in said processing chamber.

16. A reactor for processing a substrate, said reactor comprising:

a housing defining a processing chamber;

a light source supported in said housing;

a heater adapted to heat the substrate, said heater being supported in said housing;

a photon density sensor extending into said housing, said photon density sensor being adapted to measure the emissivity of the substrate and to move between a first position wherein said photon density sensor is directed to said light source and a second position wherein said photon density sensor is positioned for directing toward the substrate; and

a plurality of gas injectors supported by said housing, said plurality of gas injectors being adapted to inject at least one reactant gas into said processing chamber.

17. The reactor according toclaim 16, wherein said gas injectors are arranged into at least two groups of gas injectors, each of said groups of gas injectors being adapted to selectively deliver at least one reactant gas and an inert gas into said processing chamber.

18. The reactor according toclaim 16, further including a manifold supported by said housing said manifold being adapted to inject inert gas into said processing chamber.

19. The reactor according toclaim 18, wherein said manifold comprises an injection ring, said injection ring being positioned and adapted to align with the periphery of the substrate for at least directing inert gas onto the periphery of the substrate.

20. The reactor according toclaim 16, wherein each of said injectors is adapted to be independently controlled whereby flow of gas through each of said injectors can be independently adjusted.

21. The reactor according toclaim 16, wherein said gas injectors are arranged in a uniform pattern adapted to direct a uniform flow of a gas toward the substrate.

22. The reactor according toclaim 16, wherein said gas injectors are adapted to deliver the gas on a discrete area of the substrate.

23. The reactor according toclaim 22, further comprising an exhaust manifold, said exhaust manifold adapted to remove unreacted gas from the processing chamber and to substantially confine the gas over the discrete area of the substrate.

24. The reactor according toclaim 23, wherein said manifold extends around said plurality of gas injectors to substantially confine the gas in the processing chamber over the discrete area of the substrate, said exhaust manifold interposed between said injectors and said photon density sensor whereby said photon density sensor is free from film depositions from the gas.

25. The reactor according toclaim 16, wherein said gas injectors are arranged in with a greater concentration of said gas injectors positioned and adapted to align with a peripheral region of the substrate and with a smaller concentration of gas injectors positioned and adapted to align with a central region of the substrate whereby the gas injected by the gas injectors produces a uniform deposition on the substrate.

26. The reactor according toclaim 16, wherein said housing comprises a first housing, said reactor further comprising a second housing rotatably supported in said first housing, said second housing enclosing said heater and rotatably supporting the substrate thereon.

27. The reactor according toclaim 26, said second housing having a removable platform, said removable platform being adapted to support the substrate in said processing chamber.

28. A method of processing a semiconductor substrate comprising the steps of:

providing a processing chamber;

supporting the substrate in the processing chamber;

directing light into the processing chamber toward the substrate;

providing a photon density sensor;

directing the photon density sensor to the light;

measuring the incident photon density from the light with the photon density sensor;

repositioning the photon density sensor to direct the photon density sensor to the substrate;

measuring the reflection of the light off the substrate;

comparing the measured incident photon density to the reflected light to calculate the substrate temperature;

heating the substrate; and

injecting at least one reactant gas into the chamber through at least one injector.

29. A method of processing a semiconductor substrate according toclaim 28, wherein repositioning the photon density sensor includes rotating the photon density sensor.

30. A method of processing a semiconductor substrate according toclaim 28, wherein rotating the photon density sensor includes rotating the photon density sensor about one hundred eighty degrees.

31. A method of processing a semiconductor substrate according toclaim 28, wherein comparing the measured incident photon density to the reflected light includes:

providing a processor;

sending signals from the photon density sensor to the processor to calculate the substrate emissivity and temperature; and

calculating the temperature with the processor from the signals from the photon density sensor.

32. A method of processing a semiconductor substrate according to claim2831, wherein sending signals includes:

forming the photon density sensor on a first communications cable: and

coupling the first communications cable to the processor.

33. A method of processing a semiconductor substrate according toclaim 32, wherein coupling includes coupling the first communications cable to a second communications cable and coupling the second communications cable to the processor.

34. A method of processing a semiconductor substrate according toclaim 33, wherein coupling the first communications cable to the second communications cable includes providing a slip coupling between the first communications cable and the second communications cable.

35. A method of processing a semiconductor substrate according toclaim 28, further comprising adjusting the heating based on the temperature of the substrate.

36. A method of processing a semiconductor substrate according toclaim 28, further comprising rotating the substrate in the processing chamber, said injecting includes directing the reactant gas to a discrete portion of the substrate while the substrate is rotating.

37. A method of processing a semiconductor substrate according toclaim 36, wherein directing the reactant gas includes exhausting unreacted gas from the processing chamber to isolate the reactant gas over the discrete portion of the substrate whereby the photon density sensor remains free of undesirable film depositions from the reactant gas.

38. A method of processing a semiconductor substrate according toclaim 28, wherein injecting includes a first reactant gas through a first group of the gas injectors and injecting a second reactant gas through a second group of the gas injectors.

39. A method of processing a semiconductor substrate according toclaim 28, further comprising selectively varying the flow of the reactant gas through the gas injectors.

40. A method of processing a semiconductor substrate according toclaim 28, further comprising arranging the gas injectors in a uniform pattern to direct a uniform flow of gas into the processing chamber.

41. A method of processing a semiconductor substrate according toclaim 28, wherein injecting includes injecting the gas into the processing chamber with a non-uniform profile for uniformly depositing film on the substrate.

42. A method of processing a semiconductor substrate according toclaim 41, wherein injecting the gas into the chamber with a non-uniform profile includes arranging the gas injectors in a non-uniform pattern to direct more gas to a peripheral region of the substrate and less gas to the central region of the substrate.

43. A reactor for processing a substrate, said reactor comprising:

a housing defining a processing chamber;

a light source positioned in said housing;

a heater positioned in said housing, said heater being adapted to heat the substrate;

at least one gas injector adapted to inject at least one gas into said processing chamber onto a surface of the substrate; and

a photon density sensor positioned in said housing, said photon density sensor being adapted to measure the emissivity of the substrate and to move between a first position wherein said photon density sensor is directed to said light source and a second position wherein said photon density sensor is positioned for directing toward the substrate.

44. The reactor according toclaim 43, further comprising first and second communication cables, said first communication cable including said photon density sensor and being in communication with said second cable and being adapted to send signals from said photon density sensor to a processor.

45. The reactor according toclaim 43, wherein said first and second communications cable comprise optical communication cables.

46. The reactor according toclaim 45, wherein said first and second communications cables are interconnected by a slip connection.

47. The reactor according toclaim 46, wherein said first communication cable is rotated between said first and second positions by a driver.

48. The reactor according toclaim 44, wherein said first communications cable includes an angled portion said photon density sensor being defined on a distal end of said angle portion.

49. The reactor according toclaim 43, further comprising a second housing, said second housing being rotatably supported in said housing defining a processing chamber and being adapted to rotatably support the substrate in said processing chamber.

50. A reactor for processing a substrate said reactor comprising:

a housing defining a processing chamber;

a light source positioned in said housing;

a heater adapted to heat the substrate said heater being supported in said housing;

a photon density sensor positioned in said housing, said photon density sensor being adapted to measure the emissivity of the substrate and to move between a first position wherein said photon density sensor is directed to said light source and a second position wherein said photon density sensor is positioned for directing toward the substrate; and

at least one gas injector supported by said housing, said gas injector being adapted to inject at least one reactant gas into said processing chamber.

51. The reactor according toclaim 50, wherein said gas injector comprises a plurality of gas injectors said gas injectors are arranged into at least two groups of gas injectors, each of said groups of gas injectors being adapted to selectively deliver at least one reactant gas and an inert gas into said processing chamber.

52. The reactor according toclaim 50, further including a manifold supported by said housing, said manifold including said at least one gas injector, said manifold being adapted to inject inert gas into said processing chamber.

53. The reactor according toclaim 52, wherein said manifold comprises injection ring, said injection ring including a plurality of said gas injector said injection ring being positioned and adapted to align with the periphery of the substrate for at least directing inert gas onto the periphery of the substrate.

54. The reactor according toclaim 50, wherein said at least one gas injector comprises a plurality of gas injectors, each of said injectors is adapted to be independently controlled whereby flow of gas through each of said injectors can be independently adjusted.

55. The reactor according toclaim 50, wherein said at least one gas injector comprises a plurality of gas injectors, said gas injectors are arranged in a uniform pattern adapted to direct a uniform flow of a gas toward the substrate.

56. The reactor according toclaim 50 wherein said gas injector is adapted to deliver the gas on a discrete area of the substrate.

57. The reactor according toclaim 56, further comprising an exhaust manifold, said exhaust manifold adapted to remove unreacted gas from the processing chamber and to substantially confine the gas over the discrete area of the substrate.

58. The reactor according toclaim 57, wherein said at least one gas injector comprising a plurality of gas injectors, said manifold extending around said plurality of gas injectors to substantially confine the gas in the processing chamber over the discrete area of the substrate, said exhaust manifold interposed between said injectors and said photon density sensor whereby said photon density sensor is free from film depositions from the gas.

59. The reactor according toclaim 50, wherein said at least one gas injector comprises a plurality of gas injectors, said gas injectors are arranged in with a greater concentration of said gas injectors positioned and adapted to align with a peripheral region of the substrate and with a smaller concentration of gas injectors positioned and adapted to align with a central region of the substrate whereby the gas injected by the gas injectors produces a uniform deposition on the substrate.

60. The reactor according toclaim 50, wherein said housing comprises a first housing, said reactor further comprising a second housing rotatably supported in said first housing, said second housing enclosing said heater and rotatably supporting the substrate thereon.

61. The reactor according toclaim 60, said second housing having a removable platform, said removable platform being adapted to support the substrate in said processing chamber.

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