Sensor assembly, apparatus, and method for in-situ film growth

Abstract

To provide a sensor assembly for an epitaxial chamber for monitoring growth of an epitaxial film thickness, and a method for using the sensor assembly.SOLUTION: In a processing chamber, a sensor assembly 160 for the processing chamber includes: a sensor tube 161 containing silicon carbide and having a light path therein; and a sensor window 162 containing crystalline silicon carbide and having a proximal side 162a coupled to a distal end 161b of the sensor tube. The sensor window covers a light path 164, and a distal side 162b of the sensor window opposite to the proximal side is perpendicular to the central axis of the light path.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001]

[0001] Embodiments of the present disclosure generally relate to in situ monitoring of film growth in a processing chamber. More particularly, embodiments disclosed herein relate to a sensor assembly for an epitaxial chamber for monitoring epitaxial film thickness growth and methods of use thereof. [Background technology]

[0002]

[0002] Semiconductor substrates are processed for a wide variety of applications, including the fabrication of integrated devices and microdevices. One method of substrate processing involves depositing a material, such as a dielectric material or a conductive metal, on the top surface of the substrate in a processing chamber. For example, epitaxy is a deposition process in which a thin, ultra-pure layer, usually silicon or germanium, is grown on the surface of the substrate. Materials can be deposited in a lateral flow chamber by flowing process gases parallel to the surface of a substrate positioned on a support and thermally decomposing the process gases to deposit the material from the process gases on the substrate surface.

[0003]

[0003] Film thickness measurements of processed substrates may be used in connection with a processing step. Film thickness measurements may be performed after the processing step has been performed (e.g., offline), outside of the process chamber in which the processed substrate is processed. Offline measurements can be inefficient and reduce throughput because substrates that do not meet specifications may not be used and the process may need to be repeated several times to obtain measurements that meet specifications.

[0004]

[0004] Furthermore, film thickness measurements are difficult to perform within a process chamber and during processing because the processing equipment in the process chamber can interfere with the measurement equipment, thereby hindering measurement accuracy. For example, infrared lamp radiation and the heat emitted by the lamps can interfere with the measurement equipment.

[0005] Therefore, there is a need for an improved apparatus and method for in situ measurement of film thickness in a processing chamber. Summary of the Invention

[0006]

[0006] Implementations of the present disclosure generally relate to in situ monitoring of film growth in a processing chamber. More particularly, embodiments disclosed herein relate to a sensor assembly for an epitaxial chamber and methods of use thereof, and related apparatus.

[0007] In one implementation, a sensor assembly for a processing chamber includes a sensor tube comprising silicon carbide and having an optical path therein, and a sensor window comprising crystalline silicon carbide and having a proximal side coupled to a distal end of the sensor tube, the sensor window covering the optical path, the distal side of the sensor window facing away from the proximal side being perpendicular to a central axis of the optical path.

[0008] In one implementation, a processing chamber includes a chamber body having an upper window, a lower window, and a sidewall that define a processing region. The processing chamber includes a process gas inlet formed through the sidewall, a susceptor disposed in the processing region and having a substrate-receiving upper surface, and a preheat ring surrounding the susceptor. The processing chamber includes a rotatable shaft that supports the susceptor and a sensor assembly. The sensor assembly includes a sensor tube including silicon carbide and having an optical path therein, and a sensor window including crystalline silicon carbide and having a proximal side coupled to the distal end of the sensor tube. The sensor window covers the optical path, and the distal side of the sensor window is exposed to the processing region.

[0009]

[0009] In one implementation, a computer-readable medium is provided that stores instructions that, when executed by a processor of the system, cause the system to simultaneously deposit a film on a substrate disposed in a processing chamber and on a crystal sensor window; absorb infrared light with a sensor tube coupled to the crystal sensor window to heat the crystal sensor window at least partially through the sensor tube; measure the intensity of light reflected by or transmitted through the sensor window using an optical spectrometer; and determine at least one of the thickness and growth rate of the film deposited on the crystal sensor window based on the measured light intensity. [Brief explanation of the drawings]

[0010]

[0010] In order that the above-described features of the present disclosure may be understood in detail, the above-summarized disclosure will now be more particularly described with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings merely illustrate typical embodiments and therefore should not be considered as limiting the scope of the embodiments, as other equally effective embodiments may be permitted.

[0011] [Figure 1A] 1 is a schematic cross-sectional side view of a processing chamber according to one implementation. [Figure 1B] 1B is an enlarged schematic cross-sectional view of a portion of FIG. 1A showing an exemplary sensor assembly according to one implementation. [Figure 1C] FIG. 1B is a schematic cross-sectional side view of the processing chamber of FIG. 1A showing the placement of a sensor assembly according to one implementation. [Figure 2A] FIG. 1 is a schematic cross-sectional side view of a processing chamber illustrating an exemplary sensor assembly according to one implementation. [Figure 2B] 2B is an enlarged schematic cross-sectional view of a portion of FIG. 2A showing an exemplary sensor assembly according to one implementation. [Figure 3] FIG. 1 is a schematic cross-sectional side view of a processing chamber illustrating an exemplary sensor assembly according to one implementation. [Figure 4]1 is a schematic diagram illustrating a method for processing a substrate according to one implementation.

[0012]

[0018] To facilitate understanding, wherever possible, the same reference numerals have been used to designate identical elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0019] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to in situ monitoring of film growth in a processing chamber. By way of example, embodiments disclosed herein provide an apparatus and method for in situ monitoring of film growth and film thickness measurement in a processing chamber (e.g., an epitaxial chamber).

[0014]

[0020] The embodiments disclosed herein provide a sensor window positioned in a processing chamber to receive epitaxial film growth thereon that simulates epitaxial film growth occurring simultaneously on a substrate positioned in the processing chamber.

[0015]

[0021] The embodiments disclosed herein provide a sensor window constructed and positioned to have a temperature similar to that of a substrate being processed in a processing chamber to simulate the film deposition characteristics of the substrate.

[0016]

[0022] The embodiments disclosed herein provide a sensor window having a composition that allows for backside spectral wavelength measurements in either reflection mode, transmission mode, or both reflection and transmission modes.

[0017]

[0023] The embodiments disclosed herein provide a sensor assembly that enables spectral reflectance measurements regardless of the strong optical background radiation of the epitaxial chamber and the resulting low signal-to-noise ratio characteristics. The noise may include, for example, noise due to infrared lamp radiation in the epitaxial chamber. The sensor assembly embodiments described herein provide a sensor tube having a reflectometer optical path therein that is sealed from stray infrared radiation. The sensor assembly embodiments described herein provide a sensor tube that absorbs infrared lamp radiation and then conducts thermal energy from the sensor tube to a sensor window coupled thereto to increase the temperature of the sensor window, thereby advantageously increasing the temperature of the sensor window toward the temperature of the substrate being processed. The sensor assembly embodiments described herein provide an optical path that is isolated from the process gas flow.

[0018]

[0024] Embodiments disclosed herein provide a modulated light source capable of distinguishing transmission mode wavelength measurements resulting from infrared lamp radiation. Embodiments disclosed herein provide a sensor window with built-in band-edge transmission characteristics usable for sensor window temperature detection. Embodiments disclosed herein provide a sensor window that allows for in situ conditioning (preloading) to improve the sensitivity of the sensor window.

[0019]

[0025] 1A is a schematic cross-sectional side view of a processing chamber 100 according to one implementation. The processing chamber 100 may be used to process one or more substrates 101, including depositing material on the top surface of the substrate 101. For example, the processing chamber 100 may be used to perform an epitaxial deposition process on the substrate 101 to epitaxially grow material on the top surface of the substrate 101. In one example, the processing chamber 100 may be configured to process 300 mm substrates.

[0020]

[0026] The processing chamber 100 generally includes a chamber body 102, a support system 104, and a controller 106. The support system 104 may include components for monitoring and / or executing one or more processes performed using the processing chamber 100, such as film deposition. A controller 106, such as a programmable computer, is coupled to the support system 104 and adapted to control the processing chamber 100 and the support system 104. The controller 106 includes a programmable central processing unit (CPU) 107 operable with memory 111 (e.g., non-volatile memory) and support circuits 113. The support circuits 113 are coupled to the CPU 107 and include cache, clock circuits, input / output circuits and subsystems, power supplies, etc., coupled to various components of the processing chamber 100, and combinations thereof.

[0021]

[0027] In one or more embodiments, CPU 107 is one of any form of general-purpose computer processor used in industrial environments, such as a programmable logic controller (PLC), for controlling various monitoring system components and sub-processors. Memory 111 coupled to CPU 107 is non-transitory and typically one or more of readily available memory such as random access memory (RAM), dynamic random access memory (DRAM), static RAM (SRAM), and synchronous dynamic RAM (SDRAM (e.g., DDR1, DDR2, DDR3, DDR3L, LPDDR3, DDR4, LPDDR4, etc.)), read-only memory (ROM), a floppy disk drive, a hard disk, a flash drive, or any other form of digital storage, local or remote.

[0022]

[0028] As used herein, memory 111 is a form of computer-readable storage medium containing instructions (e.g., non-volatile memory) that, when executed by CPU 107, facilitate operation of process chamber 100. The instructions in memory 111 are in the form of a program product, such as a program (e.g., a middleware application, an instrument software application, etc.), that implements the methods of the present disclosure. The program code may conform to any one of a number of different programming languages. In one example, the present disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program(s) in the program product define the functions and steps of an embodiment (including methods, such as method 400 described herein).

[0023]

[0029] Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media in which information is permanently stored (e.g., a read-only memory device within a computer, such as a CD-ROM disk readable by a CD-ROM drive, a flash memory, a ROM chip, or any type of solid-state non-volatile semiconductor memory), and (ii) writable storage media in which changeable information is stored (e.g., a floppy disk in a diskette drive or hard disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions and steps of the methods described herein, are embodiments of the present disclosure.

[0024]

[0030] The chamber body 102 has an upper window 108, e.g., an upper dome, sidewalls 109, and a lower window 110, e.g., a lower dome, which define a processing region. A susceptor 112 used to support the substrate 101 is disposed in the processing region. The susceptor 112 may be formed from silicon carbide or silicon carbide-coated graphite. The susceptor 112 has a substrate-receiving upper surface 114. The susceptor 112 is rotatably supported by support posts 116 coupled to respective support arms 118 extending from a shaft 120. During operation, the substrate 101 disposed on the susceptor 112 may be lifted relative to the susceptor 112 by the substrate lift arms 122 via lift pins 124.

[0025]

[0031] The interior volume of the processing chamber 100 is divided into an upper chamber volume 134 (eg, a process gas region) above the plane of the susceptor 112 and a lower chamber volume 136 (eg, a purge gas region) below the plane of the susceptor 112 .

[0026]

[0032] The processing chamber 100 includes, among other components, an array of radiant heat lamps 126 for heating the susceptor 112 (e.g., its backside 115) and a preheat ring 132. Heating the susceptor 112 and preheat ring 132 contributes to the thermal decomposition of process gases onto the substrate 101, forming one or more layers on the substrate 101. The radiant heat lamps 126 may be positioned above the upper window 108, below the lower window 110, or both, as shown in FIG. 1A. The upper window 108 and lower window 110 may be formed of an optically transparent material, such as quartz, to facilitate the transmission of thermal radiation therethrough.

[0027]

[0033] The radiant heat lamps 126 can be arranged in any desired manner around the susceptor 112 to independently control the temperature in various regions of the substrate 101 to facilitate deposition of material on the upper surface of the substrate 101. While not described in detail herein, the deposition material deposited on the substrate 101 can include one or more of silicon, silicon germanium, gallium arsenide, gallium nitride, and / or aluminum gallium nitride, among other materials. The thermal energy output of each radiant heat lamp 126 can be precisely controlled using the controller 106. The radiant heat lamps 126 can be configured to heat the interior of the process chamber 100 to a temperature within a range from about 200° C. to about 1200° C.

[0028]

[0034] A reflector can optionally be placed above the upper window 108 to reflect the infrared light emitted from the substrate 101 back onto the substrate 101. The reflector can be made from a metal such as aluminum or stainless steel. The efficiency of the reflection can be improved by applying a highly reflective coating such as gold to an area of the reflector. The reflector can be coupled to a cooling source for supplying a cooling fluid such as water to the reflector to cool it.

[0029]

[0035] The upper liner 128 is disposed below the upper window 108 and is configured to reduce or prevent unwanted deposition on chamber components, such as the sidewall 109 or the peripheral portion of the upper window 108. The upper liner 128 is positioned adjacent to the lower liner 130. The lower liner 130 is configured to fit around the inner periphery of the sidewall 109. The lower liner 130 is disposed between the upper window 108 and the lower window 110. The lower liner 130 radially outwardly surrounds the lower chamber volume 136. The upper liner 128 and the lower liner 130 may be formed of quartz.

[0030]

[0036] The preheat ring 132 is coupled to the lower liner 130 and extends radially inward therefrom. The preheat ring 132 is supported on the radially inward-extending portion of the lower liner 130. The preheat ring 132 is configured to be disposed around the periphery of the susceptor 112 when the susceptor 112 is in the processing position shown in FIG. 1A . In one or more embodiments, the preheat ring 132 is formed from silicon carbide, silicon carbide-coated graphite, and / or black quartz. The temperature of the preheat ring 132 during operation may be in the range of about 100° C. to about 1100° C. The heated preheat ring 132 aids in activating the process gases flowing through the upper chamber volume 134. The preheat ring 132 can activate the process gases before they flow over the top surface of the substrate 101.

[0031]

[0037] Process gas supplied from a process gas source 138 is introduced into the upper chamber volume 134 through a process gas inlet 140 formed through the sidewall 109. The process gas inlet 140 extends at least partially between the upper liner 128 and the lower liner 130. The process gas inlet 140 is configured to direct the process gas generally radially inward, as indicated by process gas flow 170. During film formation, the susceptor 112 may be positioned in a processing position (shown in FIG. 1A ) adjacent to and generally flush (e.g., coplanar) with the end of the process gas inlet 140, thereby causing the process gas to flow in a generally planar, laminar flow along a channel defined at least partially across the top surface of the substrate 101. Although only one process gas inlet 140 is shown, the process gas inlet 140 may include two or more inlets for providing two or more separate process gas streams having different compositions, concentrations, partial pressures, densities, and / or velocities.

[0032]

[0038] The process gas exits the upper chamber volume 134 through an exhaust port, such as a process gas outlet 142, formed through the sidewall 109 of the processing chamber 102 opposite the process gas inlet 140. Exhaust of the process gas through the process gas outlet 142 is facilitated by a vacuum source, such as a vacuum pump 144, fluidly coupled downstream from the process gas outlet 142.

[0033]

[0039] Purge gas is supplied to the lower chamber volume 136 from one or more purge gas sources 148a and / or 148b. The purge gas sources 148a and 148b may be the same source, as shown, or may be different sources. The purge gas may be an inert gas, such as argon or nitrogen. The flow of purge gas in the lower chamber volume 136 helps prevent or reduce the flow (e.g., convection and diffusion) of process gas from the upper chamber volume 134 to the lower chamber volume 136. The flow of purge gas enters the lower chamber volume 136 through one or both of a side inlet 150 formed in or around the sidewall 109 and / or a bottom inlet 151 formed in the lower window 110. The side inlet 150 is located at a height below the process gas inlet 140. Distribution channels 152 are formed radially between the lower liner 130 and the sidewall 109 and vertically between the sidewall 109 and the lower window 110. The distribution channel 152 is fluidly coupled to the side inlet 150 to receive the purge gas from the side inlet 150. The distribution channel 152 can extend 360° around the lower liner 130 to facilitate even distribution of the purge gas around the lower chamber volume 136. The distribution channel 152 is fluidly coupled to the lower chamber volume 136 via a second channel 154. The illustrated second channel 154 is formed between the lower liner 130 and the lower window 110. Alternatively, the second channel 154 can be formed through the body of the lower liner 130. The second channel 154 can be formed as a single annular channel or can include multiple arc-shaped segments. The second channel 154 is positioned at an elevation below the process gas inlet 140. The illustrated second channel 154 is also positioned at an elevation below the distribution channel 152. Alternatively, the second channel 154 may be disposed at or above the level of the distribution channel 152. The second channel 154 is configured to direct purge gas generally radially inward into the lower chamber volume 136, as shown by purge gas flow 172.

[0034]

[0040] An upper chamber volume 134 is defined vertically above the plane of the susceptor 112 (e.g., above its substrate receiving surface 114 or above the substrate 101 disposed thereon) and above the preheat ring 132, vertically below the upper window 108, and radially inward of the sidewall 109. A lower chamber volume 136 is defined vertically below the plane of the susceptor 112 (e.g., below its backside 115), vertically above the lower window 110, and radially inward of the lower liner 130.

[0035]

[0041] In the substrate loading position, the susceptor 112 is lowered relative to the preheat ring 132, providing a vertical gap between their radial overlap. The substrate 101 is configured to be loaded into and unloaded from the chamber body 102 through the gap and through corresponding openings in the lower liner 130. In the processing position (shown in FIG. 1A ), the susceptor 112 is raised such that the susceptor 112 and preheat ring 132 are positioned at a height between the end of the process gas inlet 140 and the end of the second channel 154.

[0036]

[0042] The bottom inlet 151 is disposed between the shaft 120 and the lower window 110. The bottom inlet 151 is directly fluidly coupled to the lower chamber volume 136. The bottom inlet 151 is disposed at an elevation below the second channel 154. The bottom inlet 151 is configured to direct a purge gas generally upward and radially outward into the lower chamber volume 136, as indicated by purge gas flow 174. The purge gas flow 174 from the bottom inlet 151 can be configured to increase the flow of purge gas into a bottom portion of the lower chamber volume 136 compared to purge gas flow 172 alone.

[0037]

[0043] The purge gas in the lower chamber volume 136 flows into the upper chamber volume 134 between the radial overlap of the susceptor 112 and the preheat ring 132. The purge gas exits the upper chamber volume 134 through the same exhaust port as the process gas (e.g., process gas outlet 142). In one or more embodiments, the purge gas outlet may be formed through the sidewall 109. The purge gas outlet may be located opposite the process gas inlet 140 or at any radial location along the sidewall 109 relative to the process gas inlet 140. In such embodiments, a vent may be formed radially through the lower liner 130 to exhaust the purge gas from the lower chamber volume 136 directly to the purge gas outlet. In such embodiments, a vacuum pump 144 may be fluidly coupled downstream of the purge gas outlet to facilitate exhausting the purge gas through the vent and the purge gas outlet. In such embodiments, mixing of the purge gas and the process gas in the upper chamber volume 134 is reduced or prevented.

[0038]

[0044] An exemplary sensor assembly 160 for in situ monitoring of film growth in a processing chamber is shown in FIG. 1A . In FIG. 1A , a preheat ring 132 includes a mounting aperture 133 extending longitudinally through the body of the preheat ring 132, perpendicular to the plane of the preheat ring 132. In the implementation shown in FIG. 1A , the mounting aperture 133 is located on the gas inlet side of the preheat ring 132 (e.g., has a circumferential position aligned with the process gas inlet 140), such that process gas flows through the sensor assembly 160 before flowing over the substrate 101. Other locations for the mounting aperture 133 and the sensor assembly 160 are also contemplated. The mounting aperture 133 receives a portion of the sensor assembly 160 therethrough. In one or more embodiments, the mounting aperture 133 is used to couple the assembly 160 to the preheat ring 132. Although only one mounting aperture 133 is shown, the preheat ring may include multiple mounting apertures (e.g., two, three, four, five, or more mounting apertures). The mounting aperture(s) may be located at any circumferential position on the preheat ring 132, such as on the gas outlet side of the preheat ring 132 (e.g., aligned with the process gas outlet 142) or toward the middle of the preheat ring 132 (e.g., halfway between the process gas inlet 140 and the process gas outlet 142).

[0039]

[0045] The sensor assembly 160 generally includes a sensor tube 161, a sensor window 162 coupled to the sensor tube 161, and a sleeve 163 disposed around a portion of the sensor tube 161 and movable (e.g., longitudinally) relative to the sensor tube 161. The sensor window 162 may be a coupon. The sensor tube 161 has an optical path 164 therein, and the sensor window 162 covers the optical path 164. The sensor tube 161, the sensor window 162, and the sleeve 163 are disposed within the interior volume of the process chamber 100 and may therefore be referred to herein as an internal subassembly. The sensor tube 161 is disposed through the mounting aperture 133. Although only one internal subassembly including the sensor tube 161, the sensor window 162, and the sleeve 163 is shown, the sensor assembly 160 may further include one or more additional internal subassemblies, each including a sensor tube, a sensor window, and a sleeve, located at circumferential positions corresponding to one or more mounting apertures.

[0040]

[0046] 1A , the sensor window 162 is in direct contact with the pre-heat ring 132. The temperature of the pre-heat ring 132 may be about 25° C. to about 100° C. lower than the temperature of the sensor window 162. Therefore, direct contact between the pre-heat ring 132 and the sensor window 162 may contribute to thermal energy loss from the sensor window 162 to the pre-heat ring 132, which may cause the temperature of the sensor window 162 to undesirably drop toward the temperature of the pre-heat ring 132. In one or more embodiments, to reduce thermal energy loss from the sensor window 162 to the pre-heat ring 132 (e.g., by conduction), thermal insulation may be disposed between the sensor window 162 and the pre-heat ring 132, thereby advantageously maintaining the sensor window 162 at a higher temperature than the pre-heat ring 132. The sensor window 162 (e.g., its distal side facing toward the upper window 108) is exposed to the process gas region (e.g., the upper chamber volume 134) of the process chamber 100. 1A, the distal side of the sensor window 162 is parallel to the plane 139 of the preheat ring 132. In one or more embodiments, the distal side of the sensor window 162 can be positioned at an acute or obtuse angle relative to the plane 139 of the preheat ring 132.

[0041]

[0047] In one embodiment, which can be combined with other embodiments, the sensor tube 161 can be formed from silicon carbide (e.g., SiC). In one embodiment, which can be combined with other embodiments, the sensor tube 161 can be formed from sintered silicon carbide. In one or more embodiments, the silicon carbide of the sensor tube 161 has a fine-grained SiC crystal structure. The sensor tube 161 can be formed from any suitable material capable of blocking light (e.g., infrared lamp radiation) passing through its walls to seal the light path 164 from optical interference from within the interior volume of the process chamber 100. The sensor tube 161 can be formed from any suitable thermally conductive material capable of absorbing infrared radiation from the radiant heat lamp 126 (e.g., from below the lower window 110) and subsequently conducting thermal energy from the sensor tube 161 to the sensor window 162 coupled thereto, thereby increasing the temperature of the sensor window 162, thereby advantageously increasing the temperature of the sensor window 162 toward the temperature of the susceptor 112 and / or the substrate 101 disposed thereon. In one or more embodiments, the sensor window 162 and the susceptor 112, and / or the substrate 101 disposed thereon, may be at approximately the same temperature, within about ±50° C. In one embodiment, which may be combined with other embodiments, the temperature of the sensor window 162 may be approximately the same as the temperature of the susceptor 112, and / or the substrate 101 disposed thereon, during a process step for epitaxially growing material on the substrate 101.

[0042]

[0048] In one or more embodiments, the sensor window 162 may have a thickness of about 400 μm or less to advantageously reduce attenuation of light passing therethrough. In one or more embodiments, the sensor window 162 may have a crystalline structure. Advantageously, a crystalline sensor window 162 enhances light transmission and thermal conductivity compared to a corresponding amorphous material. In one embodiment, which can be combined with other embodiments, the sensor window 162 is formed from silicon carbide (e.g., SiC). Other materials are also contemplated for the sensor window 162. Advantageously, a silicon carbide sensor window 162 provides a spectral transmission signal for any silicon-based doped or undoped film deposited thereon, in contrast to a sensor window formed from silicon, which does not provide a spectral transmission signal for silicon-based films. In one embodiment, which can be combined with other embodiments, the sensor window 162 is crystalline silicon carbide. The crystal structure of the sensor window 162 is 6H, 4H, 3C, or a combination thereof. In one embodiment, which can be combined with other embodiments, sleeve 163 is formed from silicon carbide (eg, SiC), quartz (eg, black quartz or opaque quartz), or a combination thereof.

[0043]

[0049] The sensor assembly 160 includes or is coupled to a plurality of fiber optic cables 165 (165a-b) disposed within tubing 166. The tubing 166 may be formed from or coated with a material to shield the fiber optic cables 165 from high temperatures. In one embodiment, which can be combined with other embodiments, the tubing 166 includes gold plating. The fiber optic cables 165 are operable to transmit light in either direction between the optical path 164 and the optical module 167. The fiber optic cables 165 are disposed outside the interior volume of the processing chamber 100 (including the upper chamber volume 134 and the lower chamber volume 136) and therefore may be referred to herein as an external subassembly. In one or more embodiments, the fiber optic cables 165 are disposed outside the lower window 110 and are optically coupled to the optical path 164 of the sensor tube 161 through the lower window 110.

[0044]

[0050] In one or more embodiments, the outer subassembly, including at least the fiber optic cable 165, may be rotatable about an axis aligned with the radial center of the susceptor 112. If the processing chamber 100 includes multiple internal subassemblies at different locations, the outer subassembly may be selectively rotated to align with each different internal subassembly. For example, the outer subassembly may be rotated so that the fiber optic cable 165 is aligned with the optical path 164 of each corresponding sensor tube 161. In such an embodiment, by rotating the outer subassembly into rotational alignment with each of the different internal subassemblies, the film thickness and / or growth rate of a film deposited on each corresponding sensor window may be monitored, which indicates the film thickness and / or growth rate of a film deposited at different locations on the substrate 101.

[0045]

[0051] Sensor assembly 160 further includes or is coupled to optical module 167. In FIG. 1A , optical module 167 is located outside of (e.g., coupled to) process chamber 100. In one or more embodiments, optical module 167 is located within and / or integrated within process chamber 100. Optical module 167 includes light source 168 and light sensor 169. Optical module 167 is coupled to controller 106. In one or more embodiments, optical module 167 receives input instructions from controller 106 for operating sensor assembly 160. In one or more embodiments, optical module 167 communicates output data to controller 106 for downstream processing, analysis, storage, feedback control, and / or combinations thereof.

[0046]

[0052] Light source cable 165a is optically coupled to light source 168 to generate light that is directed toward sensor window 162 through optical path 164. Return cable 165b is optically coupled to light sensor 169 to sense returned light (e.g., light that reflects from or is transmitted through sensor window 162 and is directed away from sensor window 162 through optical path 164). In one or more embodiments, light source cable 165a and return cable 165b each include one or more fiber optic cables.

[0047]

[0053] In one or more embodiments, light source 168 generates light at a wavelength in a range from about 300 nm to about 700 nm. In one or more embodiments, light source 168 is configured to generate visible light, ultraviolet light, infrared light, broadband light, and / or combinations thereof. In one embodiment, which can be combined with other embodiments, light source 168 generates visible light at a wavelength in a range from about 500 nm to about 700 nm.

[0048]

[0054] Optical sensor 169 is configured to measure the optical intensity of the returned light received from optical path 164. In one or more embodiments, optical sensor 169 includes an optical spectrometer (such as a spectroscope) configured to measure wavelength-resolved intensity. Optical sensor 169 may include a diffraction grating, an optical lens, a linear array photodiode detector, and / or combinations thereof.

[0049]

[0055] 1B is an enlarged schematic cross-sectional view of a portion of FIG. 1A illustrating sensor assembly 160 according to one implementation. As shown in FIG. 1B, filler material 171 is added to the joint between sensor tube 161 and sensor window 162. In one or more embodiments, filler material 171 comprises silicon carbide (e.g., SiC) or any other suitable material for fusing opposing surfaces of sensor tube 161 and sensor window 162. Filler material 171 is formed between sensor tube 161 and sensor window 162 in mounting aperture 133 using a formation process (such as a chemical vapor deposition (CVD) process) for fusing sensor window 162 to sensor tube 161. In one or more embodiments, filler material 171 is formed using a CVD process at a process temperature greater than 1000 degrees Celsius.

[0050]

[0056] The sensor tube 161 has a proximal end 161a and a distal end 161b. A central axis 164c of the optical path 164 extends between the proximal end 161a and the distal end 161b of the sensor tube 161. In the illustrated implementation, the sensor tube 161 is straight. The sensor tube 161 may be angled or curved. The proximal side 162a of the sensor window 162 is coupled to the distal end 161b of the sensor tube 161. The sensor window 162 surrounds the distal end 161b of the sensor tube 161, including completely covering the optical path 164, thereby isolating the optical path 164 from the process gas flow 170. One advantage of isolating the optical path 164 is that the proximal side 162a of the sensor window 162 remains clean without the need for purge gas in the optical path 164.

[0051]

[0057] The distal side 162b of the sensor window 162 faces opposite the proximal side 162a. The distal side 162b is perpendicular to the central axis 164c of the optical path 164. The distal side 162b is exposed to a process gas region (i.e., the upper chamber volume 134) defined vertically above the plane of the susceptor 112 and preheat ring 132 (e.g., above their substrate receiving surfaces 114 or above the substrate 101 disposed thereon), as described above. In one or more embodiments, the film 176 deposited on the distal side 162b of the sensor window 162 and the film deposited on the substrate 101 may each include silicon (Si), silicon-germanium (SiGe), silicon phosphide (SiP), silicon arsenide (SiAs), boron-doped silicon-germanium (SiGeB), one or more other group III, IV, or V elements, or a combination thereof.

[0052]

[0058] The film 176 deposited on the sensor window 162 simulates a film deposited on the substrate 101 .

[0053]

[0059] As shown in FIG. 1B , a sleeve 163 is disposed around a proximal portion of the sensor tube 161 (e.g., around its proximal end 161 a). The sensor tube 161 and the sleeve 163 are relatively movable in a direction parallel to the central axis 164 c of the optical path 164. In one or more embodiments, the sensor tube 161 is longitudinally movable inward and outward (e.g., upward and downward) relative to the sleeve 163 to accommodate thermal expansion and contraction of the sensor tube 161 relative to the sleeve 163 during heating and cooling, respectively. The proximal end 163 a of the sleeve 163 faces toward the lower window 110 to seal the sleeve 163 with the lower window 110. In one or more embodiments, the seal between the sleeve 163 and the lower window 110 substantially prevents the passage of light. In one or more embodiments, the sleeve 163 is coupled to the interior of the lower window 110 at the proximal end 163 a. The sleeve 163 acts as a thermal barrier that facilitates reducing the temperature of the lower window 110 relative to the temperature of the sensor tube 161 .

[0054]

[0060] The sleeve 163 has a vent 173 formed through its wall to equalize pressure inside and outside the sleeve 163. In the illustrated implementation, the vent 173 is located on an outer portion of the sleeve 163 relative to the radial direction of the processing chamber 100 (e.g., facing away from the radiant heat lamps 126). This location advantageously reduces and / or minimizes infrared radiation passing through the vent 173. A radial gap 175 is formed between the overlapping portions of the sleeve 163 and the sensor tube 161 (i.e., between the inner surface 163i of the sleeve 163 and the outer surface 161o of the sensor tube 161). In one or more embodiments, the gap 175 is sized to substantially prevent light from passing through. In one or more embodiments, the radial gap 175 may be approximately 0.005 inches or less.

[0055]

[0061] During substrate processing, source light 178 from light source 168 is directed through optical path 164 toward proximal side 162a of sensor window 162. At least a portion of source light 178 is reflected as reflected light from film 176 deposited on distal side 162b of sensor window 162. Also during substrate processing, incident light 177 within upper chamber volume 134 is sequentially transmitted as transmitted light through film 176, through sensor window 162, and into optical path 164. Both the reflected and transmitted light are directed as returned light 179 through optical path 164 toward return cable 165b. The returned light 179 is measured by optical sensor 169.

[0056]

[0062] The measured light intensity of the returned light 179 is used to determine the thickness and / or growth rate of the film 176 deposited on the sensor window 162. For example, a lower light intensity may indicate a larger film thickness on the sensor window 162, and a higher light intensity may indicate a smaller film thickness on the sensor window 162, or vice versa.

[0057]

[0063] The thickness of the film 176 deposited on the sensor window 162 affects the light intensity of the returned light 179, and changes in the light intensity may indicate changes in the thickness of the film 176 deposited on the sensor window 162. In one or more embodiments, the measured spectrum of the returned light 179 may be filtered to obtain a value indicative of the measured light intensity only within a selected wavelength range. In one or more embodiments, an optical filter may be used to block portions of the returned light 179 that fall outside the selected wavelength range. In one or more embodiments, the selected wavelength range may exclude infrared light to reduce the effects of background infrared lamp radiation. In one or more embodiments, the selected wavelength range may correspond to the wavelength range generated by the light source 168 (e.g., visible light with wavelengths in the range of about 500 nm to about 700 nm). In some embodiments, the selected wavelength range may correspond to a wavelength range characteristic of the incident light 177 in the upper chamber volume 134 (e.g., its non-infrared portion).

[0058]

[0064] The sensor assembly 160 can be used to monitor film growth rates in situ in the processing chamber 100 and in real time during substrate processing. In one embodiment, which can be combined with other embodiments, the light intensity of the return light 179 is continuously monitored during substrate processing. The sensor assembly embodiments disclosed herein reduce interference from infrared lamp radiation and increase the signal-to-noise ratio of the optical sensor 169, enabling more accurate film growth measurements.

[0059]

[0065] FIG. 1C is a schematic cross-sectional side view of the processing chamber 100 of FIG. 1A illustrating the placement of a sensor assembly 160 according to one implementation. In FIG. 1C, a sensor tube 180 similar to the sensor tube 161 is disposed within the upper chamber volume 134 of the processing chamber 100. The sensor tube 180 may be formed from a material capable of blocking light (e.g., infrared lamp radiation) passing through the walls of the sensor tube 180 to seal the optical path therein from optical interference from within the interior volume of the processing chamber 100. In one or more embodiments, the sensor tube 180 has a reflective coating on its exterior. In one embodiment, which can be combined with other embodiments, the sensor tube 180 is formed from silicon carbide (e.g., SiC). In one embodiment, which can be combined with other embodiments, the sensor tube 180 is sintered silicon carbide. In one or more embodiments, the sensor tube 180 may have an amorphous or polysilicon structure. The sensor tube 180 is coupled to the upper window 108. In one or more embodiments, the sensor tube 180 may be fused directly to the upper window 108. The sensor tube 180 is positioned above the sensor window 162 and aligned on the central axis 164c of the optical path 164 (shown in FIG. 1B).

[0060]

[0066] 1C, return cable 165b and light sensor 169 are located away from light source 168 and light source cable 165a. Return cable 165b is disposed in piping 181 similar to piping 166 described above. In one embodiment, which can be combined with other embodiments, light sensor 169 is positioned to measure light intensity only in transmission mode. Return cable 165b is aligned with light path 164 to receive light transmitted through sensor tube 161, through sensor window 162, through a film disposed on sensor window 162, and through sensor tube 180. In one or more embodiments, light source 168 is a laser or lamp light source capable of generating a single wavelength or range of wavelengths. The light intensity measured by light sensor 169 is used to determine the film thickness and / or growth rate of a film deposited on sensor window 162, as described above.

[0061]

[0067] FIG. 2A is a schematic cross-sectional view of a processing chamber 200 showing an exemplary sensor assembly 260 according to one implementation. FIG. 2B is an enlarged schematic cross-sectional view of a portion of FIG. 2A illustrating the sensor assembly 260 according to one implementation. FIGS. 2A-2B are described together herein for clarity. Features of the sensor assembly 260 may be the same as corresponding features of the sensor assembly 160 in FIGS. 1A-1B unless otherwise noted. Therefore, the structure and corresponding labels for identical features are retained from FIGS. 1A-1B.

[0062]

[0068] 2A-2B, preheat ring 232 includes a mounting aperture 233a extending longitudinally parallel to plane 239 of preheat ring 232. Sensor assembly 260 generally includes a sensor tube 261 and a sensor window 262 coupled to sensor tube 261. Sensor tube 261 has an optical path 264 therein, and sensor window 262 covers optical path 264. Sensor tube 261 and sensor window 262 are positioned through mounting aperture 233a formed through the body of preheat ring 232 and a corresponding aperture 233b formed through the body of liner 230. In some embodiments, sensor tube 261 may have an outer diameter of approximately 4 mm or less so that sensor tube 261 fits within preheat ring 232 in the orientation shown in FIGS. 2A-2B.

[0063]

[0069] 2A-2B, the sensor window 262 is recessed inward of the preheat ring 232 relative to its inner radial edge 232i. In one or more embodiments, the sensor window 262 is flush with the inner radial edge 232i or disposed externally of the inner radial edge 232i. In one or more embodiments, a thermal insulator may be disposed between the sensor window 262 and the preheat ring 232. In one or more embodiments, the sensor tube 261 and the sensor window 262 may be coupled to another component of the processing chamber 200 (e.g., the sidewall 109, the upper liner 128, or any other suitable component) separate from the preheat ring 232 and the liner 230.

[0064]

[0070] The sensor window 262 (e.g., its distal side 262b facing toward the center of the processing chamber 200) is exposed to the process gas region (e.g., upper chamber volume 134) of the processing chamber 200 to receive film deposition thereon that simulates film deposition on the substrate 101. In one or more implementations during processing (e.g., as shown in FIG. 1A), the susceptor and preheat ring may be positioned at approximately the same height (e.g., have coplanar top surfaces). However, in FIGS. 2A-2B, the susceptor 112 is recessed relative to the preheat ring 232 to prevent radial overlap between the sensor window 262 and the preheat ring 232 from reducing or preventing film deposition on the sensor window 262. In one or more embodiments, the top surface of the susceptor 112 may be recessed relative to the top surface of the preheat ring 232 by a distance of about 1 mm or more, e.g., from about 1 mm to about 5 mm, e.g., about 2 mm. 2A-2B , the distal side 262b of the sensor window 262 is perpendicular to the plane 239 of the preheat ring 232. Much more infrared lamp radiation is directed perpendicularly compared to being directed parallel to the plane of the preheat ring 232. Thus, orienting the sensor window 262 perpendicular to the plane 239 of the preheat ring 232 reduces the amount of infrared radiation transmitted from the interior volume of the processing chamber 200 into the optical path 264. Therefore, blocking of infrared lamp radiation due to the materials and architecture of the sensor tube 261 and the sensor window 262 is further improved by the orientation of the sensor assembly 260 shown in FIGS. 2A-2B . In one or more embodiments, the distal side 262b of the sensor window 262 can be positioned at an acute or obtuse angle from perpendicular to the plane 239 of the preheat ring 232.

[0065]

[0071] The sensor assembly 260 includes or is coupled to a plurality of fiber optic cables 265 (265a-b) disposed within a piping 266. The fiber optic cables 265 are operable to transmit light in either direction between an optical path 264 and an optical module 267, which includes a light source 268 and an optical sensor 269. The fiber optic cables 265 are disposed at least partially through the process gas inlet 140 and optically coupled to the optical path 264 of a sensor tube 261 aligned with the process gas inlet 140. A T-connector 280 is coupled to the sidewall 109 and is fluidly coupled between the process gas source 138 and the process gas inlet 140. The fiber optic cables 265 are disposed through a linear path in the T-connector 280. Exposing the piping 266 around the fiber optic cables 265 to the process gas flow 170 in the T-connector 280 advantageously cools the fiber optic cables 265.

[0066]

[0072] A fiber optic feedthrough 281 is coupled to the T-connector 280 to route the fiber optic cable 265 from the optical module 267 to the T-connector 280. The fiber optic feedthrough 281 provides a vacuum seal around the fiber optic cable 265 to prevent gases from leaking into the processing chamber (e.g., during substrate processing at reduced pressure).

[0067]

[0073] 3 is a schematic cross-sectional side view of a processing chamber 300 illustrating an exemplary sensor assembly 360 according to one implementation. Features of the sensor assembly 360 may be the same as corresponding features of the sensor assembly 160 of FIGS. 1A-1B unless otherwise noted. Accordingly, the structure of identical features and corresponding labels are retained from FIG. 1A. In FIG. 3, the sensor assembly 360 is coupled to the susceptor 312 instead of the preheat ring 132, as described below.

[0068]

[0074] 3, the susceptor 312 includes a mounting aperture 333 extending longitudinally perpendicular to a plane 339 of the susceptor 312. The sensor assembly 360 generally includes a sensor tube 361, a sensor window 362 coupled to the sensor tube 361, and a sleeve 363 disposed around a portion of the sensor tube 361 and movable (e.g., longitudinally) relative to the sensor tube 361. The sensor tube 361 has an optical path 364 therein, and the sensor window 362 covers the optical path 364. The sensor tube 361, the sensor window 362, and the sleeve 363 are disposed within the interior volume of the processing chamber 300. The sensor tube 361 is disposed through the body of the susceptor 312. The sensor window 362 is in direct contact with the susceptor 312. Direct contact between the sensor window 362 and the susceptor 312 is advantageous in equalizing the temperature of the sensor window 362 and the temperature of the susceptor 312 through conductive heat transfer therebetween. Another advantage of coupling the sensor assembly 360 to the susceptor is that slow rotation of the susceptor 312 allows film deposition to be mapped over the full 360° circumference of the substrate 101.

[0069]

[0075] The sensor window 362 (e.g., its distal side 362b facing toward the upper window 108) is exposed to the process gas region (e.g., upper chamber volume 134) of the processing chamber 300 to receive film deposition thereon that simulates film deposition on the substrate 101. By positioning the sensor window 362 on the susceptor 312 (which is closer to the substrate 101 and has a temperature closer to that of the substrate 101), film deposition on the sensor window 362 more accurately simulates film deposition on the substrate 101 compared to sensor assembly embodiments in which the sensor window is positioned on a preheat ring as described above. In FIG. 3 , the distal side 362b of the sensor window 362 is parallel to the plane 339 of the susceptor 312. In one or more embodiments, the distal side 362b of the sensor window 362 is positioned at an acute or obtuse angle relative to the plane 339 of the susceptor 312.

[0070]

[0076] Sensor assembly 360 includes or is coupled to a plurality of fiber optic cables 365 (365a-b) disposed within conduit 366. Fiber optic cables 365 are operable to transmit light in either direction between an optical path 364 and an optical module 367, which includes a light source 368 and an optical sensor 369. In FIG. 3, an intermediate optical path 382 is formed in the body of support arm 118 and the body of shaft 120. Thus, fiber optic cable 365 is optically coupled to optical path 364 of sensor tube 361, at least partially through intermediate optical path 382. Because shaft 120 is rotatable relative to fiber optic cables 365, a rotatable coupling 384 is disposed at the proximal end of shaft 120 to couple fiber optic cable 365 to intermediate optical path 382. In the embodiment shown in FIG. 3, rotatable coupling 384 is an optical coupling. In one or more embodiments, instead of intermediate optical path 382, fiber optic cable 365 extends through support arm 118 and shaft 120 and optically couples directly to optical path 364 of sensor tube 361. In one or more embodiments, the rotatable coupling may be a rotatable fiber optic feedthrough assembly.

[0071]

[0077] 4 is a schematic diagram illustrating a method 400 for processing a substrate according to one implementation. In one or more embodiments, method 400 may be performed using one of the exemplary processing chambers and / or sensor assemblies disclosed herein. In one or more embodiments, method 400 may be in the form of instructions stored on a computer-readable medium (e.g., memory 111) that, when executed by a processor (e.g., CPU 107) of the system, causes the system to perform method 400.

[0072]

[0078] In step 402, a film is simultaneously deposited on a substrate and a crystal sensor window disposed in a processing chamber. Infrared radiation is absorbed in a sensor tube coupled to the crystal sensor window to heat the crystal sensor window at least in part through the sensor tube in step 404. In one embodiment, which can be combined with other embodiments, heating the crystal sensor window at least in part through the sensor tube includes conducting heat from the sensor tube to the crystal sensor window.

[0073]

[0079] In step 406, an optical spectrometer is used to measure the intensity of light reflected by or transmitted through the sensor window.

[0074]

[0080] In step 408, at least one of a thickness and a growth rate of the film deposited on the crystal sensor window is determined based on the measured light intensity. In one embodiment, which can be combined with other embodiments, determining the thickness and / or growth rate includes measuring multiple light intensity values of light (which may include transmitted light and / or reflected light) over one or more time intervals. The multiple light intensity values are correlated with reference data or a physical model based on Fresnel's equation of electromagnetic wave reflection to determine the growth rate over the one or more time intervals. The growth rate and / or thickness (e.g., a change in thickness) may correspond to a change in light intensity over the one or more time intervals. In one or more examples, the film thickness can be determined using the growth rate over a particular time interval.

[0075]

[0081] In one embodiment, which can be combined with other embodiments, the crystal sensor window is positioned on a susceptor disposed in a processing chamber and configured to support a substrate thereon (e.g., processing chamber 300 shown in FIG. 3). In such an embodiment, the method may further include rotating the susceptor during film deposition and creating a 360° map of at least one of the thickness and / or growth rate of the film deposited on the substrate based on corresponding determinations of the thickness and / or growth rate of the film deposited on the crystal sensor window. In such an embodiment, the determinations may be based on light intensity measurements at different degrees of rotation of the susceptor.

[0076]

[0082] In one embodiment, which can be combined with other embodiments, a map of at least one of thickness and / or growth rate of a film deposited on the substrate is created based on corresponding determinations of thickness and / or growth rate of films deposited on a plurality of crystal sensor windows. The crystal sensor windows are supported on a plurality of sensor assemblies spaced circumferentially around the substrate. The sensor assemblies can be mounted to a preheat ring using a plurality of mounting apertures spaced circumferentially around the substrate.

[0077]

[0083] The present disclosure contemplates that steps 402-408 of method 400 can be repeated. In one embodiment, which can be combined with other embodiments, steps 402-408 are repeated for a second substrate after the substrate is removed from the interior volume of the processing chamber and the second substrate is transferred into the interior volume. The present disclosure contemplates that the same sensor assembly with the same sensor window can be used for processing the second substrate, or the sensor window can be replaced with a second sensor window for processing the second substrate.

[0078]

[0084] Advantages of the present disclosure include an in-situ and real-time film thickness measurement process, accurate film growth monitoring, increased signal contrast, reduced light interference with the measurement, improved measurement resolution, increased efficiency and throughput, reduced machine downtime, and reduced costs.

[0079]

[0085] It is contemplated that one or more aspects disclosed herein may be combined. By way of example, one or more aspects, features, components, and / or characteristics of processing chamber 100, sensor assembly 160, processing chamber 200, sensor assembly 260, processing chamber 300, and / or method 400 may be combined. Furthermore, it is contemplated that one or more aspects disclosed herein may include some or all of the advantages described above.

[0080]

[0086] The present disclosure achieves unexpected results because measuring film growth in the interior volume of a processing chamber has been thought to be fraught with inaccuracies due to the use of upper and lower domes and / or illumination from lamps to heat the substrate. The present disclosure achieves the aforementioned advantages over processes that perform film measurements on substrates after the substrate has been processed and removed from the process chamber.

[0081]

[0087] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The present disclosure also contemplates that one or more aspects of the embodiments described herein can be substituted for one or more of the other aspects described. The scope of the present disclosure is determined by the following claims.

Claims

1. 1. A sensor assembly for a processing chamber, comprising: a sensor tube comprising silicon carbide and having an optical path therein; a sensor window comprising crystalline silicon carbide and having a proximal side coupled to the distal end of the sensor tube, the sensor window covering the optical path, the distal side of the sensor window facing away from the proximal side being perpendicular to a central axis of the optical path; A sensor assembly comprising:

2. The sensor assembly of claim 1 , wherein the sensor tube comprises sintered silicon carbide.

3. The sensor assembly of claim 1 , wherein the crystalline silicon carbide of the sensor window comprises at least one of a 6H, 4H, and 3C crystal structure.

4. The sensor assembly of claim 1 , further comprising a sleeve disposed around the proximal end of the sensor tube.

5. The sensor assembly of claim 4 , wherein the sleeve comprises at least one of silicon carbide, black quartz, and opaque quartz.

6. The sensor assembly of claim 4 , wherein the sleeve includes a vent formed in a wall of the sleeve.

7. The sensor assembly of claim 4 , wherein the sensor tube and the sleeve are relatively movable in a direction parallel to a central axis of the optical path.

8. The sensor assembly of claim 7 , further comprising a radial gap disposed between overlapping portions of the sensor tube and the sleeve.

9. The sensor assembly of claim 1 , wherein the sensor window is coupled to the sensor tube by a fitting, the fitting having a filler material.

10. The sensor assembly of claim 9 , wherein the filler material comprises silicon carbide.

11. 1. A processing chamber comprising: A chamber body, An upper window, a lower window, and sidewalls that define a processing region a chamber body including: a process gas inlet formed through the sidewall; a susceptor disposed in the processing region and having a substrate receiving upper surface; a rotatable shaft supporting the susceptor; 1. A sensor assembly comprising: a sensor tube comprising silicon carbide and having an optical path therein; a sensor window comprising crystalline silicon carbide and having a proximal side coupled to the distal end of the sensor tube, covering the optical path, the distal side of the sensor window being exposed to the process region; and a sensor assembly including: A processing chamber comprising:

12. The processing chamber of claim 11 , further comprising a sleeve disposed around a proximal end of the sensor tube, the proximal end of the sleeve being coupled to an interior of the lower window.

13. 12. The processing chamber of claim 11, wherein the sensor tube is disposed through a body of a preheat ring surrounding the susceptor, and a distal side of the sensor window is parallel to a plane of the preheat ring.

14. 12. The processing chamber of claim 11, wherein the sensor tube is disposed through a body of a preheat ring surrounding the susceptor, and a distal side of the sensor window is perpendicular to a plane of the preheat ring.

15. 12. The processing chamber of claim 11, further comprising a fiber optic cable disposed outside the lower window and optically coupled to an optical path of the sensor tube.

16. a T-connector coupled to the sidewall and fluidly connected between a process gas source and the process gas inlet; a fiber optic cable disposed through the linear path of the T-connector and optically coupled to the optical path of the sensor tube; The processing chamber of claim 11 further comprising:

17. the sensor tube is disposed through the body of the susceptor; a distal side of the sensor window is parallel to the plane of the susceptor; The optical path extends at least partially through the rotatable shaft. The processing chamber of claim 11.

18. 1. A computer-readable medium that, when executed by a processor of a system, causes the system to: simultaneously depositing a film on a substrate and a crystal sensor window disposed in a processing chamber; absorbing infrared radiation in the sensor tube coupled to the crystal sensor window to heat the crystal sensor window at least partially through the sensor tube; measuring the intensity of light reflected by or transmitted through the sensor window using an optical spectrometer; determining at least one of a thickness and a growth rate of the film deposited on the crystal sensor window based on the measured light intensity; A computer-readable medium having stored thereon instructions for causing a computer to execute the method.

19. 20. The computer-readable medium of claim 18, wherein heating the crystal sensor window at least partially through the sensor tube comprises conducting heat from the sensor tube to the crystal sensor window, and measuring the intensity of the light comprises filtering out a portion of light having wavelengths outside a selected wavelength range of about 500 nm to about 700 nm.

20. When the crystal sensor window is positioned on a susceptor disposed within the processing chamber and configured to support a substrate thereon, the instructions further include instructing the system to: rotating the susceptor during deposition of the film; generating a 360° map of at least one of the thickness and growth rate of the film deposited on the substrate based on the corresponding determination of the thickness or growth rate of the film deposited on the crystal sensor window; wherein the determination is based on measurements of light intensity at different degrees of rotation of the susceptor.

20. The computer-readable medium of claim 18.

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