EPI SELF-HEATING SENSOR TUBE AS IN-SITU GROWTH RATE SENSOR

A method and apparatus for determining a growth rate on a semiconductor substrate is described herein. The apparatus is an optical sensor, such as an optical growth rate sensor. The optical sensor is positioned in an exhaust of a deposition chamber. The optical sensor is self-heated using one or more internal heating elements, such as a resistive heating element. The internal heating elements are configured to heat a sensor coupon. A film is formed on the sensor coupon by exhaust gases flowed through the exhaust and is correlated to film growth on a substrate within a process volume of the deposition chamber.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to apparatus and methods for fabricating semiconductor devices. More specifically, apparatus disclosed herein relate to exhaust assemblies and growth rate sensors within an epitaxial deposition process chamber. Methods of using the same are also disclosed.

Description of the Related Art

Semiconductor substrates are processed for a wide variety of applications, including the fabrication of integrated devices and micro-devices. One method of substrate processing includes depositing a material, such as a dielectric material or a conductive metal, on an upper surface of the substrate in a processing chamber. For example, epitaxy is a deposition process that grows a thin, ultra-pure layer, usually of silicon or germanium on a surface of a substrate. The material may be deposited in a lateral flow chamber by flowing a process gas parallel to the surface of a substrate positioned on a support and thermally decomposing the process gas to deposit a material from the process gas onto the substrate surface.

Film thickness measurements of a processed substrate may be used in relation to processing operations. The film thickness measurements may be taken outside of a process chamber in which the processed substrate is processed, after the processing operations are conducted (e.g., offline). Offline measurements may involve inefficiencies and reduced throughput as substrates which do not meet specifications may not be used, and it can take several processing iterations to obtain measurements that meet specifications.

Additionally, it is difficult to conduct film thickness measurements within the process chamber and during the processing operations because processing equipment in the process chamber may interfere with measurement equipment, thereby hindering measurement accuracy. For example, infrared lamp radiation and heat emitted from the lamps can interfere with measurement equipment.

Therefore, there is a need for improved apparatus and methods for in situ measurement of film thickness in processing chambers.

SUMMARY

Embodiments of the present disclosure generally relate to in situ monitoring of film growth in processing chambers. More particularly, embodiments disclosed herein relate to sensor assemblies for epitaxial chambers and methods of use thereof, and related apparatus.

The present disclosure generally relates to process chambers for semiconductor processing. In one embodiment, a growth rate sensor suitable for use during semiconductor substrate manufacturing is described. The growth rate sensor includes a body, an optically transparent window disposed at an end of the body, a silicon containing coupon disposed inside of the body and adjacent to the optically transparent window, a resistive heating element disposed within the body and adjacent to the optically transparent window, a radiation sensor, and an optical fiber disposed between the radiation sensor and the optically transparent window.

In another embodiment, an exhaust assembly suitable for use during semiconductor substrate manufacturing is described. The exhaust assembly includes one or more exhaust passage bodies, an exhaust collector disposed at a distal end of the one or more exhaust passage bodies, and a growth rate sensor disposed within the exhaust collector. The growth rate sensor includes an optically transparent window, a silicon containing coupon disposed on a first side of the optically transparent window, and a resistive heating element disposed on a second side of the optically transparent window.

In another embodiment, a process chamber suitable for use during semiconductor substrate processing is described. The process chamber includes a chamber body, a substrate support disposed within a process volume of the chamber body, an upper window disposed above the substrate support and the process volume, a lower window disposed below the substrate support and the process volume, a gas injector disposed within the chamber body, an exhaust system disposed within the chamber body opposite the gas injector, and a growth rate sensor disposed within the exhaust system. The growth rate sensor includes an optically transparent window, a silicon containing coupon disposed on a first side of the optically transparent window, and a resistive heating element disposed on a second side of the optically transparent window.

In another embodiment, a non-transitory computer-readable medium is described. The non-transitory computer-readable medium stores instructions that, when executed by a processor, cause a computer system to perform several process operations. The process operations includes monitoring an intensity of radiation reflected by or transmitted through a growth rate sensor. The growth rate sensor further includes an optically transparent window, a silicon containing coupon disposed on a first side of the optically transparent window, and a resistive heating element disposed on a second side of the optically transparent window. The process operations further include heating the sensor coupon using an internal heating element during monitoring of the intensity of the radiation and determining a growth rate of a film deposited onto the sensor coupon from the change in the intensity of the radiation.

DETAILED DESCRIPTION

The present disclosure relates to exhaust assemblies and growth rate sensors within a semiconductor process chamber. The growth rate sensors perform in situ monitoring of film growth in a processing chamber. As an example, embodiments disclosed herein provide apparatus and methods for in situ monitoring of film growth and measurement of film thickness in processing chambers, such as epitaxial deposition chambers.

Embodiments disclosed herein provide a growth rate sensor positioned in an exhaust of the processing chamber in such a way as to receive epitaxial film growth thereon. The film growth on the growth rate sensor simulates the epitaxial film growth occurring simultaneously on a substrate positioned in the processing chamber. The growth rate sensor is heated to have a similar temperature to the substrate in the process volume of the processing chamber.

Embodiments disclosed herein enable a substrate and/or a coupon to have a temperature similar to a substrate being processed in the processing chamber to simulate the film deposition characteristics of the substrate.

Embodiments disclosed herein provide a sensor window and a substrate/coupon having a composition which enables backside spectral wavelength measurements in either reflection mode, transmission mode, or both of the reflection mode and the transmission mode.

Embodiments disclosed herein provide a sensor assembly which enables spectral reflectivity measurements with low signal-to-noise ratio characteristics inside of an epitaxial deposition chamber. The noise includes noise resulting from infrared lamp radiation in the epitaxial chambers. Sensor assembly embodiments described herein provide a sensor body with a radiation path therein. The sensor body is sealed from stray infrared radiation. Sensor assembly embodiments described herein provide a growth rate sensor which includes a resistive heating element for providing a controlled temperature of the growth rate sensor. The resistive heating element increases a temperature of the sensor window and advantageously raises a temperature of the sensor window and a substrate/coupon disposed on the sensor window towards a temperature of a substrate being processed. Sensor assembly embodiments described herein provide an optical path which is isolated from process gas flow.

Self-heating of the growth rate sensor using a resistive heating element or another heating element enables flexible installation of the growth rate sensor in various locations of the process chamber. The flexible installation location of the growth rate sensor is able to maintain improved sensitivity as the self-heating of the growth rate sensor prevents the detection sensitivity from degrading with changes in location of the sensor. Use of self-heating sensors as in-situ growth rate sensors also reduces the need for signal modulation. Heating of the window and the substrate/coupon of the growth rate sensor also assists in regeneration of the substrate/coupon during a cleaning operation within the process chamber.

In some embodiments, the growth rate sensor is positioned inside of an exhaust, such that gas flow is still provided across the growth rate sensor and radiation emitted by lamps or other radiation sources within the process volume is reduced. Reduced background radiation enables larger wavelength ranges which may be utilized by the growth rate sensor in determining the growth rate.

A quartz body is disposed around at least part of the growth rate sensor and isolates the growth rate sensor from the deposition environment.

FIG.1is a schematic illustration of a deposition chamber100, according to embodiments of the present disclosure. The deposition chamber100is an epitaxial deposition chamber. The deposition chamber100is utilized to grow an epitaxial film on a substrate, such as the substrate102. The deposition chamber100creates a cross-flow of precursors across the top surface150of the substrate102.

The deposition chamber100includes an upper body156, a lower body148disposed below the upper body156, a flow module112disposed between the upper body156and the lower body148. The upper body156, the flow module112, and the lower body148form a chamber body. Disposed within the chamber body is a substrate support106, an upper window108, a lower window110, a plurality of upper lamps141, and a plurality of lower lamps143. As shown, the controller120is in communication with the deposition chamber100and is used to control processes, such as those described herein. The substrate support106is disposed between the upper window108and the lower window110. The plurality of upper lamps141are disposed between the upper window108and a lid154. The plurality of upper lamps141form a portion of the upper lamp module155. The lid154may include a plurality of sensors (not shown) disposed therein for measuring the temperature within the deposition chamber100. The plurality of lower lamps143are disposed between the lower window110and a floor152. The plurality of lower lamps143form a portion of a lower lamp module145. The upper window108is an upper dome and is formed of an energy transmissive material, such as quartz. The lower window110is a lower dome and is formed of an energy transmissive material, such as quartz.

A process volume136is formed between the upper window108and the lower window110. The process volume136has the substrate support106disposed therein. The substrate support106includes a top surface on which the substrate102is disposed. The substrate support106is attached to a shaft118. The shaft is connected to a motion assembly121. The motion assembly121includes one or more actuators and/or adjustment devices that provide movement and/or adjustment of the shaft118and/or the substrate support106within the process volume136.

The substrate support106may include lift pin holes107disposed therein. The lift pin holes107are sized to accommodate a lift pin132for lifting of the substrate102from the substrate support106either before or after a deposition process is performed. The lift pins132may rest on lift pin stops134when the substrate support106is lowered from a process position to a transfer position.

The flow module112includes a plurality of process gas inlets114, a plurality of purge gas inlets164, and one or more exhaust gas outlets116. The plurality of process gas inlets114and the plurality of purge gas inlets164are disposed on the opposite side of the flow module112from the one or more exhaust gas outlets116. One or more flow guides are disposed below the plurality of process gas inlets114and the one or more exhaust gas outlets116. The flow guide is disposed above the purge gas inlets164. A liner163is disposed on the inner surface of the flow module112and protects the flow module112from reactive gases used during deposition processes. The process gas inlets114and the purge gas inlets164are positioned to flow a gas parallel to the top surface150of a substrate102disposed within the process volume136. The process gas inlets114are fluidly connected to a process gas source151. The purge gas inlets164are fluidly connected to a purge gas source162. The one or more exhaust gas outlets116are fluidly connected to an exhaust pump157.

The one or more exhaust gas outlets116are further connected to or include an exhaust system178. The exhaust system178fluidly connects the one or more exhaust gas outlets116and the exhaust pump157. The exhaust system178as described herein includes one or more growth monitors160a,160b. Each of the one or more growth monitors160a,160bare coupled to an optical module167a,167b. Therefore, a first growth monitor160ais coupled to a first optical module167awhile a second growth monitor160bis coupled to a second optical module167b. A first fiber optic cable165aoptically couples the first growth monitor160aand the first optical module167a. A second fiber optic cable165boptically couples the second growth monitor160band the second optical module167b.

FIG.2illustrates a cross-sectional plan view of the deposition chamber100ofFIG.1, according to embodiments of the present disclosure. The deposition chamber100includes an injector202disposed across from the exhaust system178. The injector202includes the process gas inlets114and is fluidly coupled to the process gas source151. The injector202may be disposed through as least a portion of the flow module112or may be a part of the flow module112. The exhaust system178is disposed on the opposite side of the process volume136from the injector202. The exhaust system178is formed through, attached to, or a part of the flow module.

The exhaust system178further includes at least one exhaust passage body204a,204b. The exhaust passage bodies204a,204bform an exhaust path for gas leaving the process volume136before entering an exhaust collector206. As shown inFIG.2, there is a first exhaust passage body204aand a second exhaust passage body204b. The first exhaust passage body204aand the second exhaust passage body204bare mirror images and may be similar in size and configuration. In other embodiments, there may be more or less exhaust passage bodies204a,204b. In some embodiments there is only one exhaust passage body, such that the two exhaust passage bodies204a,204bare merged into a single body. In yet other embodiments, there may be three or more exhaust passage bodies, such as three exhaust passage bodies204a,204b. The size and configuration of the exhaust passage bodies204a,204bmay change depending upon the size and operation of the deposition chamber100.

Both of the first exhaust passage body204aand the second exhaust passage body204bare coupled to the exhaust collector206on the opposite end of the exhaust passage bodies204a,204bfrom the process volume136. The exhaust collector206is configured to collect the exhaust from the first exhaust passage body204aand the second exhaust passage body204b. The exhaust collector206narrows as the exhaust collector206extends away from the exhaust passage bodies204a,204b. The growth monitors160a,160bare disposed within the exhaust collector206. The growth monitors160a,160bare disposed adjacent to an entrance to the exhaust collector206from the exhaust passage bodies204a,204b. The growth monitors160a,160bmay be placed in various positions within the exhaust collector206and/or the exhaust passage bodies204a,204b. There may be additional growth monitors208a,208b,208calso disposed within the exhaust collector206and/or the exhaust passage bodies204a,204b. The additional growth monitors208a,208b,208cmay be similar to the growth monitors160a,160bor may be different types of growth monitors, such as a quartz crystal growth monitor.

FIG.3illustrates a cross-sectional side view of the exhaust system178of the deposition chamber100ofFIG.1. Inside each of the exhaust passage bodies204a,204bis an exhaust plenum. An exhaust plenum312aof the first exhaust passage body204ais illustrated and a similar second exhaust plenum is disposed through the second exhaust passage body204b. As shown inFIG.3, the exhaust plenum312aof the exhaust system178extends through at least a portion of the flow module112, such that the exhaust plenum312aextends through the sidewall of the flow module112and interacts with the process volume136.

Gas is exhausted from the process volume136into the exhaust plenum312a. From the exhaust plenum312a, the gas is further flowed into a collector plenum316. The collector plenum316is a plenum disposed within the exhaust collector206.

One or more growth monitors160a,160bare located either within the exhaust plenum312aor within the collector plenum316. The first growth monitor160ais disposed within an inside upper surface324of the exhaust collector206and the collector plenum316. The second growth monitor160bis disposed within an inside lower surface327of the exhaust collector206and the collector plenum316. Alternatively or in addition to the placement of the growth monitors160a,160bwithin the exhaust collector, one or more similar growth monitors are positioned inside of an inner upper surface326or an inner lower surface329of the exhaust passage bodies204a,204band in communication with the exhaust plenum312a. The growth monitors160a,160bare disposed in either the inside upper surface324or the inside lower surface327of the collector plenum316so that the growth monitors160a,160bdo not block the flow path of the exhaust gases, but still enable deposition on a sensor coupon362a,362b. The first growth monitor160aincludes a sensor coupon362aoriented downward and facing the inner lower surface328. The second growth monitor160bincludes a second sensor coupon362boriented upward and facing the inside upper surface324.

Exhaust gas passes over the growth monitors160a,160band into the collector plenum316before being removed from the exhaust collector206through a conduit opening306of the exhaust conduit323. The conduit opening306is disposed at a portion of the collector plenum316opposite the end of the collector plenum316adjacent to the exhaust plenum312aand the exhaust passage bodies204a,204b. The conduit opening306is configured to enable venting of the exhaust gas within the exhaust collector206through an exhaust conduit323and to an exhaust pump157. A back sidewall321of the exhaust plenum312ais disposed adjacent to the conduit opening306and may be configured to direct gas into the conduit opening306. The conduit opening306is disposed through the inside lower surface327of the collector plenum316and opens into the exhaust conduit323. The exhaust conduit323extends downward from the conduit opening306and is fluidly connected to the exhaust pump157.

FIGS.4A-4Dillustrate different embodiments of growth monitors160a,160b,160c,160dfor use within the deposition chamber ofFIG.1. Each of the growth monitors160a,160b,160c,160dare configured to measure a change in transmission and/or reflection of radiation through a coupon, such as the sensor coupon362aofFIGS.4A and4Cor the sensor coupon362bofFIGS.4B and4D. The change in transmission and/or reflection of radiation through the coupon is caused by a growth of a film476on the sensor coupon362a,362b. As the film476grows, the radiation wavelength and intensity which passes through or is reflected off of the sensor coupon362a,362bchanges and is measured to determine a growth rate of the film476. The growth rate of the film476may be correlated to a growth rate on a substrate, such as the substrate102within the deposition chamber100. The growth monitors160a,160b,160c,160dare heated using one or more heating elements. The one or more internal heating elements may be a resistive heating element, a Peltier device, an infrared (IR) heating element, or a heated fluid conduit. Other heating devices are also contemplated and may be utilized as the one or more internal heating elements. The one or more heating elements are configured to be adjacent to the sensor coupon362,362b.

FIG.4Aillustrates a first embodiment of a growth monitor160a. The growth monitor160aofFIG.4Aincludes an outer body402and an optically transparent inner body463. The growth monitor160ais positioned such that the growth monitor160ais disposed through the inside upper surface324. The growth monitor160ais also configured such that it includes a radiation source434disposed in first optical module167a. The placement of the radiation source434within the first optical module167aalong with a radiation sensor436enables the growth monitor160aofFIG.4Ato be a reflective monitor and measure the radiation reflected by the sensor coupon362afrom the radiation beam emitted by the radiation source434. The first optical module167amay also utilize background radiation which passes through the sensor coupon362afrom the collector plenum316instead of the radiation source434.

The radiation sensor436may include an optical spectrometer. Other radiation sensors436are also contemplated and may be utilized. The radiation which is measured by the radiation sensor436is about 0.5 μm to about 6 μm, such as about 1 μm to about 5 μm, such as about 2 μm to about 4 μm. The radiation which is emitted by the radiation source434is about 0.5 μm to about 6 μm, such as about 1 μm to about 5 μm, such as about 2 μm to about 4 μm.

The outer body402and the optically transparent inner body463together form a body of the growth monitor160a. The outer body402is disposed through a wall of the exhaust system178, such that the outer body402is disposed through the inside upper surface324and a bottom of the growth monitor160ais exposed to the collector plenum316and exhaust gases passing through the exhaust system178. The transparent inner body463is transparent to radiation within a pre-determined range. In some embodiments, the transparent inner body463has a 90% or greater transmittance of radiation between a wavelength of and 0.2 μm to about 5.0 μm, such as about 0.5 μm to about 5.0 μm, such as about 1.0 μm to about 4.5 μm. The wavelength over which the transparent inner body463is transparent may be at least partially influenced by the type of heating source. The transparent inner body463may be transparent to radiation emitted by the radiation source434and radiation received by the radiation sensor436. A portion of the transparent inner body463is formed by an optically transparent window462a. The optically transparent window462ais disposed adjacent to the collector plenum316. The optically transparent window462amay be the same material or a different material from the rest of the transparent inner body463.

The sensor coupon362ais disposed adjacent to the optically transparent window462aand the transparent inner body463. The sensor coupon362aincludes a deposition surface428aand a backside surface430a. The deposition surface428ais oriented towards the inside lower surface327. The film476is grown on the deposition surface428aduring a processing operation and is correlated to a film growth on a substrate within a process volume of a semiconductor processing chamber, such as the deposition chamber100.

In the growth monitor160a, a cover404is utilized to secure the sensor coupon362ato the transparent inner body463. The cover404is configured to partially surround the sensor coupon362ato enable the cover404to secure the sensor coupon362a. As shown inFIG.4A, the outer edges of the deposition surface428aof the sensor coupon362aare covered by the cover404and held to secure the sensor coupon362a. A central portion of the deposition surface428aof the sensor coupon362ais left uncovered and exposed to the collector plenum316.

A backside sensor plenum408is formed above the sensor coupon362aand between the backside surface430aand the optically transparent window462a. The backside sensor plenum408reduces pressure on the sensor coupon362awhich may otherwise be applied by the cover404if the cover404held the backside surface430aflush with the optically transparent window462a. Utilizing the backside sensor plenum408may cause a pressure differential between the backside sensor plenum408and the collector plenum316during processing. Therefore, to prevent damage to the sensor coupon362adue to a pressure differential, one or more equalization ports (not shown) may be disposed between an outside surface of the transparent inner body463and the backside sensor plenum408to allow pressure equalization between the backside sensor plenum408and the surrounding volume, such as the collector plenum316.

The cover404may include a coupon transfer opening406. The coupon transfer opening406may be positioned either an upstream or a downstream position. The coupon transfer opening406is configured to enable transfer of the sensor coupon362ainto and out of the cover404. The bottom surface of the cover404therefore acts as a shelf and the coupon transfer opening406may have a surface co-planar with the support surface of the cover404which supports the sensor coupon362a. The coupon transfer opening406has a width at least the same size as the width of the sensor coupon362a. Therefore the coupon transfer opening406is a rectangular or arcuate opening through the transparent inner body463. The coupon transfer opening406may be patched or filled before positioning the transparent inner body463inside of the collector plenum316. The patch or fill may be a plug. The material of the patch or fill material is the same material as the transparent inner body463and may be coated or positioned using a high-temperature coating operation.

In one or more examples, a thickness of the sensor coupon362ais about 400 μm or less, such as about 200 μm to about 400 μm, such as about 250 μm to about 350 μm, such as about 300 μm. The thickness of the sensor coupon362ais configured to reduce radiation attenuation therethrough. In one or more examples, the sensor coupon362ahas a crystalline structure. Advantageously, the crystalline structured sensor coupon362aincreases radiation transmission and thermal conductivity relative to a corresponding amorphous material. Therefore, heat and radiation may be transmitted easily between the optically transparent window462aand the sensor coupon362a. Therefore, heating of the sensor coupon362ais more predictable and uniform while radiation from a radiation source easily passes through the sensor coupon362ato be measured. In one embodiment, which can be combined with other embodiments, the sensor coupon362ais a silicon containing coupon. In one embodiment, the sensor coupon362ais formed from silicon carbide (e.g., SiC). Other materials are contemplated for the sensor coupon362a. Advantageously, a silicon carbide sensor coupon362aprovides a spectral transmission signal for any silicon-based doped or undoped film deposited thereon, in contrast to a sensor coupon362aformed from only silicon which fails to provide a spectral transmission signal for silicon-based films. In one embodiment, which can be combined with other embodiments, the sensor coupon362ais crystalline silicon carbide. The crystalline structure of the sensor coupon362ais 6H, 4H, 3C, or combinations thereof.

The deposition surface428aof the sensor coupon362ahas a roughness of less than 3 nm, such as less than 2 nm, such as less than 1 nm. In one embodiment, which can be combined with other embodiments, the transparent inner body463and the optically transparent window462aare formed from silicon carbide (e.g., SiC), quartz (e.g., black quartz, black opaque quartz, or white opaque quartz), or combinations thereof. Other materials are also contemplated and may be utilized within the transparent inner body463. The material and geometry of the transparent inner body463is configured to reduce stray radiation which passes through the transparent window462aand is within the transparent inner body463. The stray radiation is reduced at a wavelength of about 300 nm to about 1000 nm, such as about 400 nm to about 800 nm.

The outer body402is a metal material and may be configured to absorb any radiation which escapes the transparent inner body463. The outer body402is a metal material, such as stainless steel. Other materials are also contemplated and may be utilized within the outer body402. In some embodiments, an inner surface of the outer body402is gold plated. Other materials are also contemplated and may be utilized as a plating or film within the outer body402. Both the outer body402and the transparent inner body463have a cylindrical outer wall and a cylindrical inner wall. In some embodiments, the inner and outer walls of the outer body402and the transparent inner body463are prisms, such as a rectangular prism, a pentagonal prism, or a hexagonal prism. Other prisms may also be utilized.

An internal heating element411is disposed within the outer body402and the transparent inner body463. The internal heating element411may be a resistive heating element, a Peltier device, or a heated fluid conduit. Other heating devices are also contemplated and may be utilized as the internal heating element411. In the embodiments described herein, the internal heating element411is a resistive heating element. The internal heating element411provides rapid and precise control of a temperature of the sensor coupon362a. In some embodiments, the internal heating element411is able to heat the sensor coupon362aand control heating of the sensor coupon362abetween about 300° C. to about 1200° C., such as about 400° C. to about 1000° C., such as about 500° C. to about 900° C. The temperature of the sensor coupon362ais controlled with a precision of less than about 10° C., such as less than about 7° C., such as less than about 5° C.

The internal heating element411includes a low resistance element412and a high resistance element410. The high resistance element410has a higher resistivity than the low resistance element412, such that the resistivity of the high resistance element410is greater than 10 times the resistivity of the low resistance element412, such as greater than 20 times the resistivity of the low resistance element412, such as greater than 50 times the resistivity of the low resistance element412. The high resistance element410is disposed adjacent to the optically transparent window462aand the sensor coupon362a. The high resistance element410has a resistivity of about 103Ω·cm to about 106Ω·cm, such as about 2000 Ω·cm to about 10,000 Ω·cm, such as about 104Ω·cm to about 105Ω·cm, such as about 105Ω·cm to about 106Ω·cm. The low resistance element412has a resistivity of about 0.1 Ω·cm to about 100 Ω·cm, such as about 1 Ω·cm to about 10 Ω·cm, such as about 10 Ω·cm to about 100 Ω·cm. The low resistance element412is configured to transfer power from one or more power sources426to the high resistance element410. The high resistance element410is configured to be heated when a power is applied thereto.

A temperature measurement device414is disposed adjacent to and/or contacting the high resistance element410. The temperature measurement device414is configured to measure the temperature of one or both of the optically transparent window462aand the sensor coupon362a. The temperature measurement device414of the growth monitor160is a thermocouple or a pyrometer. Other temperature measurement devices are also contemplated and may be utilized as the temperature measurement device414. The temperature measurement device414is coupled to a temperature measurement receiver418by wiring416. The temperature measurement receiver418is configured to apply a power to the thermocouple and measure the voltage and corresponding voltage changes of the thermocouple. In some embodiments, the temperature measurement receiver418is integrated into the controller120. In some embodiments, a band gap absorption of the sensor coupon362aand/or the optically transparent window462is measured to determine the temperature of the optically transparent window462and the sensor coupon362a. This may be in addition to or as an alternative to the temperature measurement device414.

The growth monitor160afurther includes one or more lenses424and one or more mirrors422. The lenses424and the mirrors422are configured to collimate and orient the radiation between the sensor coupon362aand the radiation sensor436. A partition432is positioned between the lower end of the growth monitor160aand the upper end of the growth monitor160a. The lower end includes the high resistance element410, the low resistance element412, the sensor coupon362a, the optically transparent window462a, the optically transparent inner body463, and the temperature measurement device414. The upper end includes the one or more lenses424and the one or more mirrors422. The partition may reduce stray radiation which interacts with the one or more lenses424and the one or more mirrors422.

One or more fiber optic cables420,165aare disposed along the radiation measurement path425. A first fiber optic cable165ais disposed between the first optical module167aand the body of the growth monitor160a. A second fiber optic cable420is disposed between the optically transparent window462/the sensor coupon362aand the mirrors422/lenses424. In some embodiments, the second fiber optic cable420is omitted.

FIG.4Billustrates a second embodiment of a growth monitor160b. The growth monitor160bofFIG.4Bis similar to the growth monitor160aofFIG.4A, but the growth monitor160bis disposed through an inside lower surface327of the exhaust collector206.

The growth monitor160ais also configured such that it includes the radiation source434and the radiation sensor436disposed in the second optical module167b. The placement of the radiation source434within the second optical module167balong with a radiation sensor436enables the growth monitor160bofFIG.4Bto be a reflective monitor and measure the radiation reflected by the sensor coupon362bfrom the radiation beam emitted by the radiation source434. The second optical module167bmay also utilize background radiation which passes through the sensor coupon362bfrom the collector plenum316instead of the radiation source434.

In the growth monitor160b, the sensor coupon362bis disposed such that a deposition surface428is oriented upward, such that the deposition surface428faces the inside upper surface324. The sensor coupon362bis disposed on top of an optically transparent window462b, such that a backside surface430bof the sensor coupon362bis disposed on the optically transparent window462b. The positioning of the sensor coupon362bon top of the optically transparent window462benables the removal of the cover404of the growth monitor160aofFIG.4Aas gravity holds the sensor coupon362bon the optically transparent window462b. The sensor coupon362bis disposed in a pocket435. The pocket435is a concave opening and is configured to receive the sensor coupon362b. The optically transparent window462bis a bottom surface of the pocket435. As the sensor coupon362bis disposed flush with the optically transparent window462bthere is also no backside sensor plenum408or equalization ports406a,406b. This opens the entire deposition surface428to exposure by exhaust gases

FIG.4Cillustrates a third embodiment of a growth monitor160c. The growth monitor160cofFIG.4Cis similar to the growth monitor160aofFIG.4A, but the radiation source434is separated from the radiation sensor436and is disposed to transmit radiation through the sensor coupon362a. The growth monitor160ctherefore measures the radiation transmitted through the sensor coupon362ainstead of reflected from the sensor coupon362a. A radiation outlet440is disposed through the inside lower surface327of the exhaust collector206.

FIG.4Dillustrates a fourth embodiment of a growth monitor160d. The growth monitor160dofFIG.4Dis similar to the growth monitor160bofFIG.4B, but the radiation source434is separated from the radiation sensor436and is disposed to transmit radiation through the sensor coupon362b. The growth monitor160dtherefore measures the radiation transmitted through the sensor coupon362binstead of reflected from the sensor coupon362b. A radiation outlet440is disposed through the inside upper surface324of the exhaust collector206.

FIG.5is a schematic diagram view illustrating a method500of processing a substrate. In one or more examples, the method500may be implemented using one of the example processing chambers and/or sensor assemblies disclosed herein. In one or more examples, the method500may be in the form of instructions stored on a computer readable medium (e.g., memory), that, when executed by a processor of a system (e.g., CPU), cause the system to implement the method500. The computer readable medium and corresponding system are part of a controller, such as the controller120.

At activity502, a film is simultaneously deposited on a substrate, such as the substrate102, and on a sensor coupon of a growth rate sensor, such as the sensor coupons362aor263b, disposed within a processing chamber, such as the deposition chamber100. Depositing the film includes flowing one or more precursors or process gases from a process gas source and heating the substrate. The process gases are flowed over the surface of the substrate as a side injection while the substrate is rotated on a substrate support or susceptor. At activity504, the sensor coupon, and an optically transparent window to which the sensor coupon is coupled, is heated using an internal heating element, such as the internal heating element411, within the growth rate sensor. In one embodiment, which can be combined with other embodiments, heating the sensor coupon and the optically transparent window at least in part through the internal heating element includes applying power to a resistive heating element disposed within the growth rate sensor. The internal heating element is heated to a predetermined temperature, which is similar to a temperature of the substrate being processed in the process volume. The difference between a substrate temperature and the coupon temperature is less than about 50° C. during the activity504, such as less than about 30° C., such as less than about 20° C. The temperature of the coupon and/or the internal heating element is measured separately using a temperature measurement device such as a thermocouple.

At activity506, an intensity of radiation reflected by or transmitted through the sensor window is measured using an optical spectrometer, which is part of a radiation sensor. During activity506radiation may also be emitted by a radiation source. The radiation source may be a laser or an optical fiber. The radiation which is measured by the optical spectrometer and emitted by the radiation source is about 0.5 μm to about 6 μm, such as about 1 μm to about 5 μm, such as about 2 μm to about 4 μm.

At activity508, at least one of a thickness or growth rate of the film deposited on the crystalline sensor window is determined based on the measured radiation intensity. In one embodiment, which can be combined with other embodiments, the determining of the thickness and/or the growth rate includes measuring a plurality of radiation intensity values of the radiation (which can include transmitted radiation and/or reflected radiation) across one or more time intervals. The plurality of radiation intensity values are correlated to reference data or physical models based on Fresnel's equations of electromagnetic wave reflection to determine the growth rate across one or more time intervals. The growth rate and/or the thickness (such as a thickness change) can correspond to a change in radiation intensity across the one or more time intervals. In one or more examples, a film thickness can be determined using the growth rate at a certain time interval.

Each of the growth monitors160a,160b,160c,160ddescribed herein may be utilized with the deposition chamber100described herein or additional versions of semiconductor processing chambers. In some embodiments, the growth monitors160a,160b,160c,160dare placed in a different semiconductor processing chamber from those described herein, such as an atomic layer deposition (ALD) chamber, a physical vapor deposition (PVD) chamber, and other versions of a chemical vapor deposition (CVD) chamber. Placement of the growth monitors160a,160b,160c,160dreduces the amount of stray radiation from lamps or other heating elements compared to if the growth monitors160a,160b,160c,160dwere located inside of the process volume136of the deposition chamber100. However, by locating the growth monitors160a,160b,160c,160dinside of an exhaust, the growth monitors160a,160b,160c,160dare not heated by the same heating elements or lamps as the substrate102. If the growth monitors160a,160b,160c,160dare not similar in temperature to the substrate102, the quality of film growth and removal from a sensor coupon, such as the sensor coupons362a,362b, is degraded. Therefore, the growth monitors160a,160b,160c,160das described herein have an internal heating element411disposed therein.

The internal heating element411enables the growth monitors160a,160b,160c,160dto be held at a temperature similar to the temperature of the substrate102while still having reduced background radiation. The use of a self-heated growth monitor160a,160b,160c,160dfurther enables flexible placement of the growth monitors160a,160b,160c,160dthroughout the deposition chamber100. Therefore, the growth monitors160a,160b,160c,160dmay be placed in different portions of the exhaust system178. Placement of the growth monitors160a,160b,160c,160dwithin the exhaust system178further reduces the complexity of the system inside of the process volume136compared to if the growth monitors160a,160b,160c,160dwere placed inside of the process volume136.

In embodiment of the present disclosure, a process chamber suitable for use during semiconductor substrate processing is described. The process chamber includes a chamber body, a substrate support disposed within a process volume of the chamber body, an upper window disposed above the substrate support and the process volume, a lower window disposed below the substrate support and the process volume, a gas injector disposed within the chamber body, an exhaust system disposed within the chamber body opposite the gas injection, and a growth rate sensor disposed within the exhaust system. The growth rate sensor includes an optically transparent window, a silicon containing coupon disposed on a first side of the optically transparent window, and a resistive heating element disposed on a second side of the optically transparent window.

In some embodiments, the growth rate sensor further includes a body, a radiation sensor, and an optical fiber disposed between the radiation sensor and the optically transparent window, wherein the optically transparent window is disposed at an end of the body and the resistive heating element is disposed inside of the body. The body further includes an outer body and an optically transparent inner body, wherein the optically transparent window is part of the optically transparent inner body.