Signal-to-noise correction method for accurate film measurement
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-04-08
- Publication Date
- 2026-08-14
Smart Images
Figure 2026527506000001_ABST
Abstract
Description
Technical Field
[0001]
[0001] Embodiments of the present disclosure generally relate to a system and method for signal-to-noise ratio correction in an epitaxial chamber that integrates in-situ reflectivity measurements for real-time process monitoring.
Background Art
[0002] Description of Related Art
[0002] In-situ reflectivity measurement is a technique employed to measure the optical properties of a thin film while the thin film is being deposited. This process involves directing a beam of light at the film and quantifying the amount of light that is reflected. By analyzing the reflected light, valuable information regarding the film thickness, refractive index, and extinction coefficient can be obtained.
[0003]
[0003] This method has particular significance in semiconductor manufacturing as it enables real-time monitoring of epitaxial film growth. Epitaxy refers to the process of growing a thin film of one material on top of another material with a specific crystal orientation. This is an important step in manufacturing various semiconductor devices including transistors and lasers.
[0004]
[0004] In-situ reflectivity measurement plays an important role in measuring the thickness of an epitaxial film during the deposition process. It is extremely important to accurately control the film thickness in order to achieve desired electrical and optical properties. Furthermore, this technique can determine the refractive index and extinction coefficient of the film and assist in identifying its composition and potential structural defects.
[0005]
[0005] There are various advantages to employing insitu reflectance measurement in epitaxy for semiconductor manufacturing. Firstly, real-time monitoring is possible, allowing for early detection of problems that may occur during film growth and preventing defects. Secondly, by continuously monitoring the growth process, optimal deposition conditions can be determined and implemented, resulting in higher quality films. Finally, implementing insitu reflectance measurement helps reduce manufacturing costs by minimizing the occurrence of defects in the film, which can lead to more efficient production of semiconductor devices.
[0006]
[0006] However, during insitu reflectance measurement, several noise sources may be present that may affect the measurement and epitaxial process controlled by the insitu reflectance measurement. These noise sources include instrument noise, ambient noise, and sample noise.
[0007]
[0007] Instrument noise originates from the measuring instrument itself and can be caused by various factors such as electronic equipment, light sources, and detectors. Environmental noise, on the other hand, is caused by external factors surrounding the measuring instrument, including vibration, temperature fluctuations, and electromagnetic interference. Finally, sample noise originates from the sample being measured and can be affected by factors such as surface roughness, defects, and impurities.
[0008]
[0008] The presence of noise can pose challenges in epitaxy measurements. This can introduce inaccuracies into the measurement of the optical properties of the film and affect the determination of the film thickness, refractive index, and extinction coefficient. Furthermore, noise can obscure defects within the film structure, making their identification and characterization more difficult.
[0009]
[0009] Therefore, there is a need for an improved insitu reflectance measurement system for use in epitaxy that reduces noise and improves the accuracy of epitaxial film growth. [Overview of the project]
[0010]
[0010] Embodiments of this specification generally relate to semiconductor manufacturing, and more specifically to systems and methods for improved signal-to-noise ratio correction in epitaxial chambers integrating insitu reflectance measurements for real-time process monitoring.
[0011]
[0011] In one embodiment, a substrate processing system is provided. The substrate processing system includes a processing chamber and a susceptor assembly disposed within the processing chamber and configured to rotate a substrate. An insitu reflectance measurement (ISR) system is connected to the processing chamber and the ISR system is configured to receive an ISR signal that describes the characteristics of the substrate placed on the susceptor assembly. A controller is connected to the processing chamber and is configured to determine the substrate rotation speed, use the substrate rotation speed to determine the time per substrate rotation, use the time per substrate rotation to determine the ISR sample acquisition per rotation, select an integer value, use the integer value and the ISR sample acquisition per rotation to calculate the total sample value, determine whether the total sample value is a pure integer, and if it is determined that the total sample value is a pure integer, to calibrate the ISR signal using the total sample value.
[0012]
[0012] In another embodiment, a system for insitu reflectance measurement (ISR) is provided. The system includes a light source, a collimator in optical communication with the light source, a dichroic mirror positioned above the upper housing module of a processing chamber, and a sensor configured to receive reflected light from the dichroic mirror. The system further includes a controller configured to receive an ISR signal from the sensor indicating the reflected light, determine a substrate rotation speed, use the substrate rotation speed to determine the time per substrate rotation, use the time per substrate rotation to determine the ISR sample acquisition per rotation, select an integer value, use the integer value and the ISR sample acquisition per rotation to calculate a total sample value, determine whether the total sample value is a pure integer, and calibrate the ISR signal using the total sample value.
[0013]
[0013] In yet another embodiment, a method for insitu reflectance measurement (ISR) is provided. This method includes determining a substrate rotation speed, determining the time per substrate rotation using the substrate rotation speed, determining the ISR sample acquisition per rotation using the time per substrate rotation, selecting an integer value, calculating a total sample value using the integer value and the ISR sample acquisition per rotation, determining whether the total sample value is a pure integer, and calibrating the ISR signal of an insitu reflectance measurement system using the total sample value.
[0014]
[0014] A more detailed description of the Disclosure, which has been briefly summarized above, can be obtained by referring to embodiments, so that the above-mentioned features of the Disclosure may be understood in more detail. Some embodiments are shown in the accompanying drawings. However, it should be noted that the accompanying drawings show only exemplary embodiments and should not be considered to limit the scope of the Disclosure, and other effective embodiments may be permitted. [Brief explanation of the drawing]
[0015] [Figure 1]
[0015] This is a schematic cross-sectional view of a system comprising an insitu reflectance measurement system for processing a substrate, according to a particular embodiment. [Figure 2A]
[0016] This is a partial schematic cross-sectional view of the insitu reflectance measurement (ISR) system shown in Figure 1, according to a specific embodiment. [Figure 2B]
[0017] This is a partial schematic cross-sectional view of the ISR system shown in Figure 1, according to a specific embodiment. [Figure 3]
[0018] This is a schematic block diagram of a method for improving the signal-to-noise ratio for insitu reflectance measurement according to a specific embodiment. [Modes for carrying out the invention]
[0016]
[0019] For ease of understanding, the same reference numerals have been used to indicate identical elements common to the figures, where possible. It is assumed that elements and features of one embodiment can be usefully incorporated into other embodiments without further description.
[0017]
[0020] Embodiments of this specification generally relate to semiconductor manufacturing, and more specifically to systems and methods for improved signal-to-noise ratio correction in epitaxial chambers integrating in-situ reflectance measurements for real-time process monitoring.
[0018]
[0021] Insitu reflectance measurement measures the optical properties of thin films during deposition. By illuminating the film with light and analyzing the reflected light, information on the film's thickness, refractive index, and extinction coefficient can be obtained. This real-time monitoring of epitaxial film growth enables optimization of deposition conditions and improvement of film quality.
[0019]
[0022] However, there are challenges associated with insitu reflectance measurements, particularly the presence of noise. Noise sources include instrument noise from the measuring instrument itself, environmental noise from the surrounding environment, and sample noise from sample irregularities and / or caused by the film itself, and especially in patterned samples, the reflected signal can change with sample rotation. This noise can introduce inaccuracies into the measurement of film properties and mask defects within the film structure.
[0020]
[0023] This disclosure provides a system and method for an improved signal-to-noise ratio in in-situ reflectivity measurement (ISR). In particular, this disclosure provides a processing system having an ISR system. The ISR system is configured to determine the substrate rotation speed via a controller, and then to determine the time per substrate rotation using the substrate rotation speed. The ISR sample acquisition per rotation is then calculated using the time per substrate rotation and the ISR sample acquisition rate. The total sample value is calculated using the ISR sample acquisition per substrate rotation using an integer value. The total sample value is then used to average or correct the incoming ISR signal to the controller. This correction improves the signal-to-noise ratio of the ISR signal, and in particular improves the accuracy and precision of epitaxial growth on patterned substrates.
[0021]
[0024] One feature of this disclosure is the consideration of periodicity based on the rotation of the lift. Periodicity is the total number of samples during the ISR period, after which the sensor looks at the same position and repeats. Therefore, periodicity depends on the rotation speed of the substrate. The received ISR signal is calibrated, but if the periodicity is inaccurate, the calibrated signal will be inaccurate. Based on periodicity, the total number of signals is averaged for all fibers, including the reference fiber, and placed at the last position of the ISR period T, and the method is repeated until the data retrieval or deposition process is completed. This averaging smooths the signal, reduces noise, and preserves signal change data during the deposition process without loss. Furthermore, the signal-to-noise ratio is significantly improved, and the accuracy and precision of the ISR measurement are enhanced.
[0022]
[0025] FIG. 1 is a schematic cross-sectional view of a system 101 for processing a substrate according to an embodiment. The system 101 includes a process chamber 100. The process chamber 100 is an epitaxial deposition chamber and can be used as part of a cluster tool. The process chamber 100 is utilized to grow an epitaxial film on a substrate such as substrate 150. The process chamber 100 creates a cross-flow of precursors (e.g., process gases) across the upper surface of the substrate 150 during processing. The system 101 uses a process chamber 100 configured to perform an epitaxial deposition process on the substrate 150. Alternatively, the process chamber 100 may be a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, a physical vapor deposition (PVD) chamber, an etching chamber, an ion implantation chamber, an oxidation chamber, or other processing chamber.
[0023]
[0026] The process chamber 100 includes an upper housing module 102, a lower housing module 104, a chamber body assembly 106, a susceptor assembly 124, a lower window 120, and an upper window 122. The upper housing module 102 can also be part of a lid or a process chamber lid. The susceptor assembly 124 is disposed between the upper housing module 102 and the lower housing module 104. The lower window 120 is disposed between the susceptor assembly 124 and the lower housing module 104. The upper window 122 is disposed between the susceptor assembly 124 and the upper housing module 102.
[0024]
[0027] The upper housing module 102 is disposed above the susceptor assembly 124 and is configured to heat a substrate such as the substrate 150 disposed on the susceptor assembly 124. The upper housing module 102 includes an upper module body 126 and a plurality of lamp apertures 128 disposed through the upper module body 126. Each of the plurality of lamp apertures 128 includes an upper lamp 130 disposed therein. Each of the upper lamps 130 is connected to a lamp base 129. Each of the lamp bases 129 supports one of the upper lamps 130 and electrically connects each of the upper lamps 130 to a power source (not shown). Each of the lamps 129 is fixed in a generally vertical orientation within the aperture 128.
[0025]
[0028] The upper housing module 102 includes a pyrometer passage 131. The pyrometer passage 131 (also referred to as a light pipe) extends through the upper module body 126 from a first (e.g., lower) surface of the upper module body 126 to a second (e.g., upper) surface of the upper module body 126. The pyrometer passage 131 is configured to allow light to travel between the surface of the substrate 150 and an in-situ reflectivity measurement (ISR) system 185.
[0026]
[0029] The upper plenum 180 is defined between the lower surface of the upper module body 126 and the upper window 122. The upper plenum 180 is supplied with heated gas. An exhaust passage 142 for the heated gas is also disposed through the upper module body 126. The exhaust passage 142 for the heated gas is connected to a heated exhaust pump 140. The heated exhaust pump 140 removes gas from the upper plenum 180.
[0027]
[0030] The lower housing module 104 is positioned below the susceptor assembly 124 and is configured to heat the underside of the substrate 150, which is positioned on top of the susceptor assembly 124. The lower housing module 104 includes a lower module body 182 and a plurality of lamp openings 186 positioned through the lower module body 182. Each of the lamp openings 186 contains a lower lamp 188 positioned therein. Each of the lower lamps 188 is positioned in a generally vertical orientation and connected to a lamp base 184. Each of the lamp bases 184 supports one of the lower lamps 188 and electrically connects each of the lower lamps 188 to a power supply.
[0028]
[0031] During the substrate processing process, the upper lamp 130 is powered to generate radiant energy (e.g., heat) and direct that radiant energy toward the substrate 150 and the susceptor 157 of the susceptor assembly 124. During the substrate processing process, the lower lamp 188 is powered to generate radiant energy directed upward toward the substrate 150 and the susceptor 157.
[0029]
[0032] The lower lamp module 104 includes a susceptor shaft passage 195 and a pyrometer passage 192. The support shaft 155 of the susceptor assembly 124 is positioned through the susceptor shaft passage 195. The susceptor shaft passage 195 is centrally located through the lower module body 182. The susceptor shaft passage 195 allows the support shaft 155 of the susceptor assembly 124 and a portion of the lower window 120 to pass through the lower module body 182.
[0030]
[0033] A pyrometer passage 192 is positioned outside the susceptor shaft passage 195, passing through the lower module body 182, so that a lower pyrometer 190, such as a scanning pyrometer, can measure the temperature of the lower surface of the substrate 150 or the lower surface of the susceptor 157 of the susceptor assembly 124. The lower pyrometer 190 is positioned below the lower module body 182, adjacent to the pyrometer passage 192. The pyrometer passage 192 extends from the lower surface of the lower module body 182 to the upper surface of the lower module body 182.
[0031]
[0034] The upper chamber space 111 is part of the processing space 110 where the substrate 150 is processed and one or more process gases are injected. The lower chamber space 113 is part of the processing space 110 where the substrate 150 is loaded onto (or removed from) the susceptor assembly 124. The upper chamber space 111 can also be understood as the space above the susceptor 157 while the susceptor assembly 124 is in the processing position. The susceptor assembly 124 is shown in the lower position in Figure 1 (e.g., the loading position of the substrate 150). The lower chamber space 113 is understood as the space below the susceptor 157 of the susceptor assembly 124 while the susceptor assembly 124 is in the processing position. The processing position is the position where the substrate 150 is positioned at or above the level of the horizontal plane 125.
[0032]
[0035] An upper cooling ring 118 and a lower cooling ring 112 are located on opposite sides of the chamber body assembly 106. The upper cooling ring 118 is positioned above the injection ring 116 and is configured to cool the injection ring 116. The lower cooling ring 112 is positioned below the injection ring 116. The upper cooling ring 118 includes a coolant passage 146 through which it is positioned. The coolant circulating through the coolant passage 146 may include water, oil, or another fluid. The lower cooling ring 112 includes a coolant passage 148 through which it is positioned. The coolant circulating through the coolant passage 148 is similar to the coolant circulating through the coolant passage 146 of the upper cooling ring 118. The upper cooling ring 118 and the lower cooling ring 112 can help to hold the injection ring 116 in place. The upper cooling ring 118 may partially support the upper ramp module 102, while the lower cooling ring 112 may partially support the lower ramp module 104.
[0033]
[0036] By using the upper cooling ring 118 and the lower cooling ring 112, the temperature of the injection ring 116 can be reduced without requiring additional cooling channels that penetrate the injection ring 116. The use of the upper cooling ring 118 and the lower cooling ring 112 reduces the production cost of the injection ring 116, which may require more frequent replacement than the upper cooling ring 118 and the lower cooling ring 112. This disclosure assumes that the injection ring 116 may include one or more additional cooling passages formed within it.
[0034]
[0037] To supply gases such as process gases to the processing space 110, one or more gas injectors 108 are arranged through one or more openings in the injection ring 116. This disclosure assumes that multiple gas injectors may be arranged through the injection ring 116. The gas injectors may be positioned at an angle greater than about 5° from the XY plane of the substrate 150 (e.g., an angle greater than about 10° from the XY plane). Each injector is fluidly coupled to one or more process gas sources, such as a first process gas source or a second process gas source. For example, only the first process gas source is used. If both the first and second process gas sources are used, there may be two gas outlets in each gas injector. Alternatively, the first process gas source may be a process gas and the second process gas source may be a cleaning gas. The cleaning gas may be used to clean features of the ISR system 185 or features of the reflectometer system in the processing space 110.
[0035]
[0038] The upper window 122 is positioned between the injection ring 116 and the upper housing module 102. The upper window 122 is optically transparent, allowing radiant energy produced by the upper lamp module 102 to pass through it. The upper window 122 is made of quartz or glass material. The upper window 122 is dome-shaped and may be referred to as an upper dome, although planar windows are also conceivable. The outer edges of the upper window 122 form one or more peripheral supports 172. The peripheral supports 172 are thicker than the central portion of the upper window 122. The peripheral supports 172 are positioned above the injection ring 116. The peripheral supports 172 are connected to the central portion of the upper window 122. The peripheral supports 172 are optically opaque and may be made of opaque quartz.
[0036]
[0039] The lower window 120 is positioned between the susceptor assembly 124 and the lower lamp module 104. The lower window 120 is an optically transparent window, allowing radiant energy produced by the lower lamp module 104 to pass through it. The lower window 120 is made of quartz or glass material. The lower window 120 is dome-shaped and may be referred to as a lower dome, although a planar lower window 120 is also conceivable. The outer edges of the lower window 120 form a peripheral support 170. The peripheral support 170 is thicker than the central portion of the lower window 120 and connects to the central portion of the lower window 120.
[0037]
[0040] Various liners and heaters are arranged inside the chamber body assembly 106 and within the processing space 110. As shown in Figure 1, an upper liner 156 and a lower liner 154 are arranged inside the chamber body assembly 106. The upper liner 156 is positioned above the lower liner 154 and inside the injection ring 116. The upper liner 156 and the lower liner 154 are configured to be connected together, or the upper liner 156 is supported on the lower liner 154. The upper liner 156 and the lower liner 154 are configured to protect the inner surface of the injection ring 116 from process gases in the processing space 110. The upper liner 156 and the lower liner 154 also help to reduce heat loss from the processing space 110 to the injection ring 116. Reduced heat loss improves the uniformity of heating of the substrate 150, enabling more uniform deposition on the substrate 150 during the processing steps (e.g., epitaxial deposition steps). The preheating ring (PHR) 161 is supported on the ledge 160 of the lower liner 154.
[0038]
[0041] The upper heater 158 and lower heater 152 are also positioned within the chamber body assembly 106 and the processing space 110. As shown in Figure 1, the upper heater 158 is positioned between the upper liner 156 and the injection ring 116, and the lower heater 152 is positioned between the lower liner 154 and the injection ring 116. Both the upper heater 158 and the lower heater 152 are positioned inside the chamber body assembly 106, allowing for more uniform heating of the substrate 150 while it is inside the process chamber 100. The upper heater 158 and the lower heater 152 reduce heat loss to the walls of the chamber body assembly 106, creating a more uniform temperature distribution around the processing space 110. Both the upper heater 158 and the lower heater 152 may be configured for heated fluid to pass through them, or they may be resistance heaters. The upper heater 158 and the lower heater 152 are further shaped to accommodate openings that pass through the injection ring 116, such as substrate loading ports. Additionally or alternatively, the process chamber 100 may be heated using an upper lamp 130, a lower lamp 188, or a combination of both. The lamps may be positioned vertically or horizontally as shown in the figure.
[0039]
[0042] The susceptor assembly 124 is positioned within the processing space 110 and configured to support the substrate 150 during processing. The moving assembly 194 is configured to rotate the susceptor assembly 124 and the substrate 150 during the substrate processing step. The susceptor assembly 124 includes a planar substrate support surface 153 for supporting the substrate 150 and a shaft 155 extending through the lower window 120 and a portion of the lower ramp module 104. The susceptor assembly 124 is coupled to the moving assembly 194 and includes, for example, one or more motors or other actuators. The moving assembly 194 is coupled to a controller 196 to induce rotation (stepwise or continuous), vertical movement, angular tilt, or other movement around axis A. The controller 196 can indicate the presence of the susceptor assembly 124 to the spectrometer, flash the light source 244 (Figures 2A, 2B), and store data in memory (not shown).
[0040]
[0043] Figure 2A is a schematic cross-sectional view of a portion of the ISR system 185 of the system 101 shown in Figure 1, according to one embodiment. The ISR system 185 further includes a light source 244, a collimator 215, a sensor 245, a pyrometer 207, one or more preheating ring sensors 221 (two are shown), and a dichroic mirror 205 connected to or positioned above the upper housing module 102. The ISR system 185 facilitates the measurement of one or more properties of the substrate 150 (or a thin film placed thereon). Exemplary properties include temperature, thin film growth rate, or thin film thickness.
[0041]
[0044] Light source 244 is configured to produce light 241. For example, light source 244 may be a flash lamp capable of producing full-spectrum or partial-spectrum light. In one example, the spectrum of the produced light has wavelengths from about 200 nm to about 4 micrometers (e.g., 200 nm to about 800 nm or 3 micrometers to 4 micrometers). Full-spectrum light allows for a wide range of optical signals for analysis, but the light source may be limited to specific wavelengths or wavelength ranges of light to complete the analysis. Light source 244 may be controlled by controller 196. Light source 244 is in optical communication with collimator 215 and directs light 241 towards collimator 215 as instructed by controller 196. Optical communication includes connection by optical fiber cable, but other optical transmission methods are also conceivable. The path of light traveling from light source 244 may be referred to as the propagation path. Parallel light 243 leaves collimator 215 and travels through light pipe 131. The light pipe 131 can be made of any material that can transmit light (e.g., sapphire). The light pipe 131 directs parallel light 243 to the surface of the substrate 150 (or a thin film thereon) to facilitate the measurement of one or more properties of the substrate 150 (or a thin film thereon). In addition to, or as an alternative to, the measurement of the substrate 150, it is assumed that the susceptor surface (or other surface) may be measured. For example, the susceptor surface may be measured to establish an initial data set for vibration calibration. As used herein, the thin film and the substrate may be used interchangeably unless one or the other is explicitly excluded in the description.
[0042]
[0045] Parallel light 243 is reflected by the target measurement surface, such as the substrate 150, and returns as reflected light 227. The reflected light 227 returns through the light pipe 131. The reflected light 227 exits the light pipe 131 and travels along the path of the reflected light 227 to a dichroic mirror 205 aligned with the light pipe 131. The dichroic mirror 205 may be made of a transparent material with a dielectric coating. The dielectric coating may include, but is not limited to, magnesium fluoride, tantalum pentoxide, and titanium dioxide. The dichroic mirror 205 reflects certain wavelengths of light but allows other specially selected wavelengths to pass through. The wavelength range directed to the sensor 245 may be from about 100 nm to about 1000 nm, for example, within the range of 200 nm to 800 nm, for example, within the range of 200 nm to 400 nm, for example, within the range of 400 nm to 800 nm. The dichroic mirror 205 enables the use of multiple light-based sensors by directing a first desired range of light to one sensor and sending the remaining wavelengths of light to at least one other sensor. In this way, the ISR system 185 provides a compact measurement system, allowing more sensors to be mounted in a smaller footprint. The dichroic mirror 205 is positioned or oriented in a plane approximately perpendicular to the longitudinal axis of the light pipe 131 at an incident angle A1 in the range of approximately 30° to approximately 60°, for example, 35° to 55°. However, other incident angles are also conceivable.
[0043]
[0046] As shown in Figure 2A, the light reflected from the dichroic mirror 205 is transmitted along the optical path 211 to the pyrometer 207. Only wavelengths of light from approximately 1.0 μm to approximately 6.0 μm, for example, from approximately 3.0 μm to approximately 4.0 μm, travel along the optical path 211 to the pyrometer 207. As described above, the properties of the dichroic mirror 205 are selected to transmit or reflect light in a specific wavelength range. The light 247 that has passed through the dichroic mirror 205 along the path is made parallel by the collimator 215. The parallel light 213 is directed to the sensor 245. For example, the sensor 245 may be an optical spectrometer, a spectrometer configured to measure wavelength-resolved intensity. The sensor 245 may further include a grating, optical lenses, filters, a charge-coupled device (CCD) spectrometer, or a linear array photodiode detector. The filter 241 may be a short-pass filter or a dielectric filter to limit noise from the lamp 128. Dielectric filters include any thin-film based filters that can prevent the passage of specific wavelengths of light. Although filter 241 is described as part of sensor 245, it is conceivable that filters may be located elsewhere. For example, filter 241 may be part of dichroic mirror 205. Filter 241 is configured to allow only light of specific wavelengths to pass through. In one example, filter 241 allows only light with wavelengths less than 550 nm to pass through, reducing optical signal noise from the process chamber lamp and thus improving measurement accuracy. It is conceivable that filter 241 may be placed in any optical path including light reflected from substrate 150 (e.g., reflected light 227 to sensor 245) (e.g., reflected light 247 from dichroic mirror 205) (e.g., parallel light 243). In one example, filter 241 is an integrated component of sensor 245, but in other embodiments, filter 241 is a component separate from sensor 245. Filter 241 may not be included in the path, reducing the cost, complexity, and footprint of the ISR system 185.
[0044]
[0047] The pyrometer 207, one or more PHR sensors 221, and sensor 245 may be connected to a controller 196 to facilitate their control or process. The controller 196 may store information, data, algorithms, or other control parameters for performing the operations described herein. The controller 196 includes a central processing unit (CPU), memory containing instructions, and CPU support circuitry. The controller 196 controls various items directly or via another computer or controller. The controller 196 may be communicatively connected to a dedicated controller, which functions as a central controller.
[0045]
[0048] The controller 196 includes a computer processor (e.g., a CPU) used to control various board processing chambers and equipment, as well as subprocessors on or within them. Memory, or non-temporary computer-readable media, is one or more of the following: 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), floppy disks, hard disks, flash drives, or any other form of digital storage (local or remote). Support circuits for the controller 196 are connected to the CPU to support it. The support circuits include caches, power supplies, clock circuits, input / output circuits, and subsystems. Operating parameters and processes are stored in memory as software routines that are executed or invoked to transform the controller 196 into a controller for a specific purpose and to control the operation of the system 101 described herein. The controller 196 is configured to perform any of the operations described herein. When an instruction stored in memory is executed, it causes one or more of the processes described herein to be performed.
[0046]
[0049] The upper housing module 102 may further include at least a preheating ring (PHR) sensor 221 and a PHR sensor passage 219. The PHR sensor passage 219 extends through the upper module body 126 from a first surface of the upper module body 114 to a second surface of the upper module body 126. The PHR sensor passage 219 is configured to allow light 219 to travel between the surface of the substrate 150 and the ISR system 185. The ISR system 185 includes a housing 103 that houses one or more optical elements therein to facilitate processing of optical signals.
[0047]
[0050] The ISR system 185 may optionally include one or more PHR sensors 221 positioned to receive data indicating the characteristics of the preheating ring of system 101. Each PHR sensor 221 is configured to be aligned with the PHR sensor passage 219 (e.g., vertically or optically aligned). The PHR sensors 221 are spectrometers or pyrometers configured to measure the characteristics of the preheating ring (PHR), such as PHR 161 (shown in Figure 1). In one example, each PHR sensor 221 is configured to read a reference material in or on the PHR 161 for use as a film thickness reference. For example, the reference material may be a crystalline coupon with known properties. Each PHR sensor passage 219 extends between the lower and upper surfaces of the upper module body 126. In such an example, the PHR sensor passage is vertically aligned with (or directed towards) the PHR 161 (shown in Figure 1). The upper and lower ends of the PHR sensor passage 219 may be sealed with a material that can transmit light 229 (such as quartz or sapphire). Alternatively, each PHR sensor passage 219 may include an optical fiber cable placed above it.
[0048]
[0051] In addition, the preheating ring sensor 221 allows for the estimation of the film thickness at the outer periphery or edge of the substrate 150, since the outer periphery of the substrate 150 is close to the preheating ring 161. Therefore, when deposition occurs on the preheating ring 161 during processing, the preheating ring sensor 221 can determine the film thickness on the preheating ring sensor. This thickness is an estimate of the thickness of the deposited film at the edge of the substrate 150. Thus, the film thickness at the center of the substrate 150 can be determined using measurements taken through the pyrometer passage 131, while the film thickness at the edge of the substrate 150 can be determined using measurements from the ring sensor 221. Therefore, the uniformity of the deposited film from the center to the edge is determined by the input and can be corrected if necessary. It is assumed that the uniformity from the center to the edge can be corrected by changing one or more processing parameters during the deposition process.
[0049]
[0052] During processing, light from light source 244 is used to determine the film thickness or film thickness deposition rate. The light is directed from light source 244 to collimator 215, for example, by an optical fiber cable. The collimator 215 directs the light towards the surface to be measured (e.g., substrate 150). The light is reflected as reflected light from its surface. The reflected light from the measurement surface 150 facilitates the measurement of film thickness (or film thickness growth rate) and temperature. The reflected signal returns to a dichroic mirror and is divided into multiple paths (e.g., propagation subpaths). The first propagation subpath directs the reflected light to a pyrometer 207, while the second propagation subpath directs the reflected light to collimator 215 and then to sensor 245. The light intensity collected by sensor 245 is analyzed for true reflectivity and compared to a film model (e.g., Fresnel equation) using nonlinear fitting equations or other empirically derived equations to determine the film thickness.
[0050]
[0053] In one example, a film thickness model is empirically derived by acquiring absorption / reflectance data for light of a given wavelength for various films at multiple film thicknesses. The data may be collected under process conditions that approximate a given process recipe for processing future substrates, such as the process recipe in which the model is used. The data is then fitted into equations, such as nonlinear equations. The light received by sensor 245 is analyzed for intensity (e.g., the true reflectance of the light reflected from the measured subject) and fitted into empirically derived equations to determine the film thickness. In other words, the amount of light reflected from the surface of substrate 150 changes as a function of the film thickness on the surface of substrate 150. This data or equation may also take into account other optical properties of the film, such as the refractive index and extinction coefficient, to improve measurement accuracy.
[0051]
[0054] Figure 2B is a partial schematic cross-sectional view of the system shown in Figure 1 according to another embodiment. The ISR system 185 in Figure 2B is configured similarly to the ISR system 185 in Figure 2A, except that the pyrometer 207 receives light 211 that has passed through the dichroic mirror 205, and the collimator 215 receives light 247 reflected from the dichroic mirror 205. The collimator 215 can then parallelize the light 247 from the dichroic mirror 205. The sensor 245 can then receive the parallel light 213. In one embodiment, the collimator 215 may receive and parallelize reflected light 227 from the substrate before the dichroic mirror 205. In such an embodiment, the dichroic mirror 205 receives the parallel light. In the shown embodiment, the pyrometer 207 is located above the mirror housing 103, and the path of the reflected light 227 to the pyrometer 207 is shorter.
[0052]
[0055] In the ISR system 185, the measured light intensity 213 is used to determine the thickness or growth rate of the film deposited on the surface 150. For example, a lower light intensity may indicate a thicker film (because more light is absorbed), and a higher light intensity may indicate a thinner film (because more light is reflected). Conversely, depending on the composition and optical properties of the specific material being measured, the opposite may also be true.
[0053]
[0056] The thickness of the deposited film on surface 150 affects the light intensity of light 213 received by sensor 245, so that changes in light intensity can be signaled as changes in the thickness of the deposited film on surface 150. In one or more embodiments, the measured spectrum of the reflected light 213 may be filtered to provide values indicating light intensity measured only within a selected wavelength range. Such embodiments are beneficial because radiation from the lamp (e.g., upper lamp 130) is filtered out, improving the measurement accuracy at sensor 245. An optical filter 421 may be used to block a portion of the reflected light 227 that contains light of wavelengths outside the selected wavelength range. This can occur, for example, when light from the upper lamp 130 is directed into the pyrometer passage 131, such as by being reflected off one or more internal chamber surfaces. Since unintended light can affect the measurement results at sensor 245, filtering out unintended wavelengths improves measurement accuracy. In one or more embodiments, the selected wavelength range may exclude infrared radiation to reduce the influence of background infrared lamp radiation. The wavelength range generated by the light source 244 may be light with wavelengths in the range of approximately 200 nm to approximately 780 nm (e.g., approximately 200 nm to approximately 500 nm, or approximately 200 nm to approximately 400 nm, or approximately 500 nm to approximately 700 nm). The upper lamp 130 (or other lamps in the chamber) may be an infrared lamp. In such an example, the filter 421 restricts the path of light in the infrared wavelength range (IR-A, IR-B, or IR-C), for example, light with wavelengths from 780 nm to 1.3 micrometers. Thus, the sensor 245 receives only the light generated from the light source 244, improving the measurement accuracy of the light reflected from the surface of the substrate 150. In another embodiment, the filter 421 filters out light above 500 nm (e.g., above 550 nm) because signal degradation at high temperatures (e.g., above 200°C, e.g. above 600°C) begins in the range of 500 nm to 550 nm, and degradation occurs at wavelengths above 550 nm. This disclosure reduces interference from infrared lamp radiation and increases the signal-to-noise ratio of the optical sensor 245 for more accurate film growth measurement.
[0054]
[0057] Sensor 245 is used to monitor the film growth rate in-situ within the processing chamber 100 and in real time during substrate processing. In-situ monitoring improves throughput compared to conventional methods because it does not require removing the substrate from the process chamber to perform thickness measurements. In one embodiment, which can be combined with other embodiments, the light intensity of the reflected light 213 is monitored continuously over the substrate processing or at predetermined intervals over the substrate processing. Once the desired film thickness is achieved, the deposition process is stopped. The substrate 150 may then be removed from the process chamber 100, or further processing may occur within the process chamber 100 according to the process recipe.
[0055]
[0058] Figure 3 shows a method 300 for signal-to-noise ratio correction for use in the ISR system 185, which can be performed by the controller 196. In step 302 of method 300, the substrate rotation speed of the ISR system 185 is determined. For example, the substrate rotation speed may be determined by obtaining the susceptor assembly rotation speed for the process from the controller 196. Alternatively, the substrate rotation speed may be determined by obtaining the operating speed of one or more motors of the moving assembly 194. Or, the substrate rotation speed may be determined based on user input to the controller 196, for example, via a user interface (not shown). In step 304, the time per substrate rotation is determined, for example, by the controller 196 using the substrate rotation speed determined in step 302. For example, the time per substrate rotation is calculated by dividing the time interval (e.g., 60 seconds) by the substrate rotation speed. Then, in step 306, the ISR sample acquisition rate is multiplied by the time per substrate rotation to determine the ISR sample acquisition per rotation. The ISR sample acquisition rate may be 5 Hz, 10 Hz, 20 Hz, or higher.
[0056]
[0059] In step 308, an integer value is selected. The integer value may initially be any desired integer. In step 310, the total sample value is calculated using the ISR sample acquisition per revolution in step 306 and the integer value in step 308. For example, the total sample value can be produced by multiplying the ISR sample acquisition per revolution by the integer value. In step 312, the total sample value is evaluated to determine if it is a pure integer. If not, the method returns to step 308 to select a new different integer value, then returns to step 310 to recalculate the total sample value using the new integer value, and then re-evaluates whether the recalculated total sample value is a pure integer. If the total sample value is a pure integer, in step 314, the total sample value is set as the calibration threshold.
[0057]
[0060] The integer value should be as small as possible while ensuring that the total sample value is a pure integer. This allows for the smallest possible total sample value (integer), improving averaging and reducing the amount of sample collected by the ISR system to calibrate the ISR signal. For example, to select an integer value n in step 308, you would initially set n to 1 and then increase the integer value by adding 1 with each iteration of step 308 until step 312 is satisfied (e.g., n+1).
[0058]
[0061] In step 316, the signal calibration process is initiated using the calibration threshold from step 314. Specifically, the calibration process includes signal averaging incorporating the calibration threshold. The calibration threshold indicates which fiber index averaging is initiated and the number of points to average. For example, a substrate rotation speed of 30 rpm with an ISR sample acquisition rate of 10 Hz produces 20 total sample values. This means that, for example, the signal acquired from the collimator 215, for example, from reflected light 227 through multiple optical fiber cables, is corrected from an average of 20 fiber indices 20 (e.g., indices 1-20) and continues until the process is complete. This calibration process is performed for all optical fiber cables from which data is acquired. This correction reduces noise caused by rotation and other system faults, improves the signal-to-noise ratio, and improves ISR deposition.
[0059]
[0062] As shown, this disclosure provides a system and method for improving the calibration of ISR signals received from an ISR system during a deposition process such as epitaxial deposition. In particular, the ISR system is configured to calculate the total sample value using system characteristics, including substrate rotation speed, time per substrate rotation, ISR sample acquisition per rotation, ISR sample acquisition rate, and integer values, via a controller. The total sample value is then used to calibrate the incoming ISR signal. This correction takes into account periodicity based on lift rotation. Based on periodicity, the total number of signals is averaged using the total sample value and placed at the end of the ISR period for all fibers. This averaging results in noise reduction while maintaining the integrity of the signal change data collected during the deposition process. Furthermore, the improved signal-to-noise ratio enhances the accuracy and precision of the ISR measurement.
[0060]
[0063] When describing elements of this disclosure, or exemplary aspects or embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to indicate that there is one or more elements.
[0061]
[0064] The terms "comprising," "including," and "having" are intended to be comprehensive, meaning that there may be additional elements beyond those listed.
[0062]
[0065] In this specification, the term “coupled” is used to refer to a direct or indirect connection between two objects. For example, if object A is in physical contact with object B, and object B is in contact with object C, objects A and C may be considered coupled to each other even if they are not in direct physical contact. For example, a first object may be coupled to a second object even if the first object is not in direct physical contact with the second object.
[0063]
[0066] While the above applies to embodiments of the present disclosure, other embodiments and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure. The scope of the present disclosure is determined by the following claims.
Claims
1. A substrate processing system, Processing chamber and A susceptor assembly is placed inside the processing chamber and configured to rotate the substrate, An insitu reflectance measurement (ISR) system connected to the processing chamber, configured to receive an ISR signal indicating the characteristics of a substrate placed on the susceptor assembly, It is a controller, Calculate the total sample value. To determine whether the total sample value is a pure integer, and If it is determined that the total sample value is a pure integer, the ISR signal is calibrated using the total sample value. A controller and A substrate processing system comprising:
2. The substrate processing system according to claim 1, wherein calculating the total sample value includes selecting an integer value and using the integer value and the ISR sample acquisition per revolution.
3. The substrate processing system according to claim 2, wherein determining the ISR sample collection per rotation includes using the substrate rotation speed and the time per substrate rotation.
4. A substrate processing system according to claim 1, wherein determining the time per substrate rotation includes converting the substrate rotation speed using a time interval.
5. The substrate processing system according to claim 1, wherein determining the ISR sample collection per revolution includes using the sample collection rate of the ISR system.
6. The substrate processing system according to claim 1, wherein selecting an integer value includes selecting an initial integer value and incrementing the integer value from the initial integer value each time it is determined that the total sample value is not a pure integer.
7. The substrate processing system according to claim 1, wherein the calibration of the ISR signal includes setting the total sample value as a calibration threshold, and averaging the ISR signal by the total sample value if the amount of the ISR signal exceeds the calibration threshold.
8. A system for insitu reflectance measurement (ISR), Light source and A collimator that is in optical communication with the aforementioned light source, A dichroic mirror positioned above the upper housing module of the processing chamber, A sensor configured to receive reflected light from the dichroic mirror, It is a controller, Receiving an ISR signal from the sensor indicating reflected light, Calculate the total sample value. To determine whether the total sample value is a pure integer, and Calibrate the ISR signal using the total sample value. A controller and A system equipped with these features.
9. The system according to claim 8, wherein calculating the total sample value includes selecting an integer value and using the integer value and the ISR sample acquisition per revolution.
10. The system according to claim 9, wherein determining the ISR sample collection per rotation includes using the substrate rotation speed and the time per substrate rotation.
11. The system according to claim 8, wherein determining the time per board rotation includes converting the board rotation speed using a time interval.
12. The system according to claim 8, wherein determining the ISR sample collection per revolution includes using the sample collection rate of an insitu reflectance measurement system.
13. The system according to claim 8, wherein selecting an integer value includes selecting an initial integer value and incrementing the integer value from the initial integer value whenever it is determined that the total sample value is not a pure integer.
14. The system according to claim 8, wherein calibrating the ISR signal includes setting the total sample value as a calibration threshold, and averaging the ISR signal by the total sample value if the amount of the ISR signal exceeds the calibration threshold.
15. A method for insitu reflectance measurement (ISR), Calculating the total sample value, Determining whether the total sample value is a pure integer, Using the aforementioned total sample values, the ISR signal of the insitu reflectance determination system is calibrated. Methods that include...
16. The method according to claim 15, wherein calculating the total sample value includes selecting an integer value and using the integer value and the ISR sample collection per revolution.
17. The method according to claim 16, wherein determining the ISR sample collection per rotation includes using the substrate rotation speed and the time per substrate rotation.
18. The method according to claim 15, wherein determining the time per substrate rotation includes converting the substrate rotation speed using a time interval.
19. The method according to claim 15, wherein selecting an integer value includes selecting an initial integer value and incrementing the integer value from the initial integer value each time it is determined that the total sample value is not a pure integer.
20. The method according to claim 15, wherein calibrating the ISR signal includes setting the total sample value as a calibration threshold, and averaging the ISR signal by the total sample value if the amount of the ISR signal exceeds the calibration threshold.