System and method for mapping thickness variations of a substrate in a manufacturing system

Abstract

In particular, disclosed embodiments describe systems and methods for scanning a substrate with a light beam and detecting, for each of a set of substrate locations, a respective one of a set of intensity values ​​associated with the light beam reflected from (or transmitted through) the substrate, the detected intensity values ​​being used to determine a thickness profile of the substrate.

Description

Technical Field

[0001] This specification generally relates to ensuring quality control of materials manufactured in a substrate processing system. More particularly, this specification relates to the optical inspection of substrate thickness variations during various stages of a manufacturing process.

Background Art

[0002] Modern materials manufacturing often involves various deposition techniques such as chemical vapor deposition (CVD) techniques or physical vapor deposition (PVD) techniques, in which one or more selected types of atoms are deposited onto a substrate (wafer) held in a low-vacuum or high-vacuum environment provided by a vacuum deposition chamber. Materials manufactured in this way can include single crystals, semiconductor films, fine coatings, and numerous other substances that are actually used, such as in electronic device manufacturing. Many of these applications rely on the purity of the materials grown in a substrate processing system. The need to maintain separation of the environment between chambers and minimize its exposure to the ambient atmosphere and contaminants therein gives rise to various robotic techniques for sample handling and inspection. Improving the accuracy, reliability, and efficiency of such robotic techniques presents several technical challenges, and their successful solution facilitates the continued advancement of electronic device manufacturing. This is particularly true considering that the requirements for the quality of chamber-manufactured products are constantly increasing.

Summary of the Invention

[0003] In one embodiment, a method includes scanning a substrate with a first beam of light and, for each of a plurality of locations on the substrate, obtaining one of a first plurality of intensity values associated with a second beam of light, the second beam of light being caused by an interaction between the first beam of light and the substrate, and using the first plurality of intensity values to determine profile data characterizing thickness variations of the substrate.

[0004] In one embodiment, the system is configured to scan a substrate. The system includes a first light source for emitting a first light beam. The system further includes a first optical sensor for obtaining, for each of a plurality of locations on the substrate, one of a first plurality of intensity values associated with a second light beam, wherein the second light beam is caused by an interaction between the first light beam and the substrate. The system further includes a processing device for determining profile data characterizing thickness variations of the substrate using the first plurality of intensity values.

[0005] In one embodiment, the system includes a movable stage for supporting a substrate. The system further includes a light source for directing a first light beam to scan a substrate being transported on the movable stage. The system further includes a first optical sensor for obtaining, for each of a plurality of locations on the substrate, one of a first plurality of intensity values associated with a second light beam, wherein the second light beam is caused by an interaction between the first light beam and the substrate. The system further includes a processing device communicatively coupled to the first optical sensor for generating profile data characterizing thickness variations of the substrate.

Brief Description of the Drawings

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[0007] The embodiments disclosed herein provide optical mapping of thickness variations of substrates and wafers due to non-uniformities resulting from wafer manufacturing processes including polishing, etching, material deposition, etc. for smoothing, adding, and / or removing materials. For example, the disclosed embodiments may enable determination of wafer thickness measurements using methods that can be integrated into larger processing tools such as chemical mechanical polishing (CMP). For example, wafer measurements may include determining variations in thickness profiles resulting from deposition and / or etching processes. In some embodiments, the deposition may include epitaxial silicon carbide (SiC) deposition, which may occur after CMP. Further, when the thickness variation profile is known, the measurement data may indicate the best way to correct unwanted thickness variations and create a surface that is as uniform as possible (or achieve other target thickness variations as may be specified by the technology process being implemented). For example, the thickness variation profile may be used in a feedback process within the processing chamber to further add or remove material, such as a transparent film, from the substrate as needed.

[0008] Precise thickness measurement can be useful in many disciplines of technical and commercial interest, including the production of flat semiconductor wafers (e.g., optical flats). During the manufacturing processes of optical flats and semiconductor wafers, thickness non-uniformities can occur within the range of several microns. Further, the thickness variations of the wafers generally have low spatial frequencies across the wafer. In some embodiments, the purpose of thickness measurement of a semiconductor wafer, e.g., a transparent semiconductor wafer, is not the absolute thickness itself, but rather the thickness variation across the wafer, since the absolute thickness can be controlled within a few microns. For example, in some manufacturing operations (e.g., CMP operations) performed on a semiconductor wafer, the intention can be to produce a wafer that is as flat and uniform as possible.

[0009] Thus, it can be advantageous to have information related to the quality, roughness, etc. regarding the thickness variation of the surface before the manufacturing process is completed, in order to enable correction of processing errors and defects while the sample is still inside the processing system. In some embodiments, the target surface can have a complex profile, including some ridges, dents, kinks, grooves, flat regions, rounded regions, etc. For example, the thickness profile of a wafer surface can be represented by the dependence of the height (width, depth) of the target surface h(x,y) counted from some reference surface (e.g., a horizontal or vertical plane) on the coordinates (e.g., x,y) along this reference surface. The profile can be characterized by a discrete (or quasi-continuous) set of locations with a resolution determined by the spacing (e.g., Δx,Δy) between adjacent locations. The spacing can be preset based on the desired resolution of the target surface imaging.

[0010] Existing techniques for performing precise thickness measurements can include the use of capacitive probes, confocal microscopes, interferometric methods, etc., and each of these techniques has respective advantages and disadvantages when applied to specific use cases. For example, interference techniques (both absolute and differential) can provide good sensitivity for both large and small substrates and have been implemented with varying degrees of success.

[0011] However, in many cases, optical techniques for performing thickness measurements (also referred to as wafer shape metrology) often require the measurement of two separate surfaces individually to obtain two separate maps, and the comparison of such maps enables the determination of wafer thickness variations. Such methods require a sophisticated setup in which proper alignment depends on an optical flat that needs to be precisely held with respect to the semiconductor wafer in a highly stabilized environment. Thus, constantly monitoring and mapping thickness variations can be time-consuming and costly. Such a stand-alone and highly optimized setup may be undesirable, especially when on-board metrology is required.

[0012] Aspects and embodiments of the present disclosure address these and other shortcomings of the existing art. Methods and setups for efficient optical thickness measurement of substrates are described herein. This can facilitate compact, stable, and affordable data collection that can provide high-sensitivity and high-resolution information regarding the effectiveness of a technology process, such as deposition (such as epitaxial silicon carbide (SiC) deposition, which can occur after CMP), etching, CMP, or any other manufacturing process. Further, the solution can be implemented as an on-board metrology system.

[0013] During a manufacturing process involving an optical flat and a semiconductor wafer, thickness non-uniformities can occur within the range of several microns. Further, the variation in the thickness of the wafer generally has a low spatial frequency across the wafer. Thus, assuming that the wafer of interest is transparent at a particular wavelength of electromagnetic radiation (such as the optical wavelength), the passage of coherent radiation through the wafer occurs with multiple internal reflections. By exploiting such a phenomenon, an etalon type interferometer can be implemented to map the thickness variation across the surface of the wafer.

[0014] The disclosed embodiments relate to various manufacturing techniques using processing chambers (which may include deposition chambers, etching chambers, etc.), such as chemical mechanical polishing (CMP) techniques, chemical vapor deposition (CVD) techniques, physical vapor deposition (PVD), plasma CVD, plasma PVD, sputter deposition, atomic layer CVD, combustion CVD, catalytic CVD, evaporation, molecular beam epitaxy techniques, etc. The most significant practical impact of the disclosed embodiments can be expected to occur in techniques using vacuum deposition chambers (such as ultra-high vacuum CVD or PVD, low pressure CVD, etc.), although the same systems and methods can be utilized in atmospheric pressure deposition chambers for non-invasive monitoring of chamber conditions present during the deposition process.

[0015] FIG. 1 shows an exemplary embodiment of a manufacturing machine 100 capable of supporting efficient thickness variation measurement of a substrate being processed according to one embodiment. In one embodiment, the manufacturing machine 100 includes a loading station 102, a transfer chamber 104, and one or more processing chambers 106. The (one or more) processing chambers 106 may be interfaced with the transfer chamber 104 via a transfer port (not shown). The number of (one or more) processing chambers associated with the transfer chamber 104 may vary (as an example, three processing chambers are shown in FIG. 1). The transfer chamber 104 includes a robot 108, a robot blade 110 for supporting a substrate (e.g., a wafer or a transparent wafer), one or more light sources 112 for scanning the substrate 116 (e.g., a target), and a light sensor 114 disposed in one of the processing chambers 106. The (one or more) light sources 112 and the light sensor 114 may be part of a thickness mapping device 111. The transfer chamber 104 may be maintained at a pressure (temperature) higher (or lower) than atmospheric pressure (temperature).

[0016] The robot 108 can transfer various products and devices (e.g., semiconductor wafers, substrates, liquid crystal displays, reticles, calibration devices) between the loading station 102 and one of the processing chambers 106.

[0017] In one embodiment, the robot blade 110 of the robot 108 supports the substrate 116 when the substrate 116 is transferred to one of the processing chambers 106. The robot blade 110 can be attached to an extendable arm sufficient to reach between different chambers. One or more light sources 112 can scan the substrate 116 with one or more light beams to obtain intensity values caused by the reflection of one or more light beams from the substrate 116. The substrate 116 can be a wafer, substrate chuck, edge ring, or any other object / tool disposed in one of the processing chambers 106 (or in the loading station 102, transfer chamber 104, or a port connecting the transfer chamber 104 to the loading station 102 or processing chamber 106). The reflected light beam can be received by one or more light sensors 114. The thickness mapping device 111 can include an alignment point for proper alignment with the substrate 116. The alignment point can be a hole, notch, or recess and can be located at the center within a pocket or recess of the robot blade 110. The light sensors 114 of the thickness mapping device 111 can be capable of detecting visible light or other electromagnetic radiation coming from (e.g., reflected by) the target surface of the substrate 116. The light detected by the light sensors 114 can be reflected from a target surface to which the light can be directed by one or more light sources 112. In some embodiments, the light sources 112 can be mounted on the same thickness mapping device 111. In other embodiments, the light sources 112 are disposed outside the thickness mapping device 111 and can be mounted, for example, inside the transfer chamber 104, loading station 102, or processing chamber 106. The robot blade 110 can supply (and remove) substrates to (and from) one or more processing chambers 106 through a slit valve port (not shown) while the lid(s) to the one or more processing chambers 106 remain closed. The one or more processing chambers 106 may contain processing gases, plasmas, and various particles used in a deposition process.A magnetic field may exist inside the (one or more) processing chambers 106. The inside of the (one or more) processing chambers 106 may be maintained at a temperature and pressure different from the temperature and pressure outside the (one or more) processing chambers 106. The temperature and pressure inside the (one or more) processing chambers 106 may be similar to those corresponding to actual on-line processing conditions. Although the substrate 116 is shown as being supported and moved by the robot blade 110 of the robot 108, in other embodiments, the substrate 116 may be moved using a dedicated motion stage, or any other suitable movable stage, an existing substrate transfer mechanism, an existing motion mechanism in a process chamber (such as a polishing head or another wafer deployed in a CMP process).

[0018] The computing device 118 may include an optical sensor control module 122 and a thickness analysis module 124. The optical sensor control module 122 may control the operation of the optical sensor 114 and, in some cases, the (one or more) light sources 112. The thickness analysis module 124 may receive the intensity values measured by the optical sensor 114 and determine a thickness variation map of the substrate 116.

[0019] In an exemplary embodiment, the electronics module 150 may be capable of facilitating wireless thickness variation mapping of a target inside the manufacturing machine 100 to determine profile data corresponding to thickness variations of the substrate. The electronics module 150 may include a microcontroller and a memory buffer coupled to the microcontroller. The memory buffer may be used to collect and store data before sending the data to the computing device 118. In some embodiments, the data may be sent using a wireless communication circuit. In other embodiments, the data may be sent using a wired connection between the electronics module 150 and the computing device 118. In some embodiments, the data may first be stored (buffered) in the memory buffer before being sent to the computing device 118. In other embodiments, the data may be sent to the computing device 118 without being stored in the memory buffer when the data is collected. In some embodiments, the wireless or wired connection may be continuous. In other embodiments, the wireless or wired connection may be established periodically or upon completion of an inspection or some other triggering event (e.g., when the memory buffer is nearly full). The electronics module 150 may further include a power element and a startup circuit. In some embodiments, the power element may be a battery. In some embodiments, the power element may be a capacitor. The power element may be rechargeable from a power station. The microcontroller may be coupled to one or more optical sensors 114. The optical sensors 114 may include a light source and a light detector. The electronics module 150 may also include an accelerometer for facilitating accurate extension and angular rotation of the robotic blade 110. The electronics module 150 may also include a temperature sensor for detecting the temperature near the substrate 116.

[0020] The electronics module 150 may further include a wireless communication circuit, i.e., a wireless circuit for receiving wireless instructions from the computing device 118 and for sending intensity values to the computing device 118. For example, in one embodiment, the wireless circuit may include an RF front-end module and an antenna (e.g., a UHF antenna) that may be an internal ceramic antenna. The battery may be of a type with high temperature resistance, such as a lithium-ion battery, that can be exposed to a chamber temperature of 450 degrees C for short time periods such as 1 to 8 minutes.

[0021] Some components may be disposed on or in the fixed portion of the robot 108. For example, a microcontroller, a memory buffer, and an RF front-end may also be disposed. Other components of the electronics module 150 may be on or in the robot blade 110 of the robot 108 and / or on or in a thickness mapping device supported by the robot blade. The robot blade may be movable to support a substrate that can be transported by the robot blade. For example, an optical sensor 114, an accelerometer, and a temperature sensor may also be disposed. In some embodiments, some of the components of the electronics module 150 may be disposed in both the fixed portion of the robot 108 and the extensible robot blade 110, for example, a power element may also be disposed. In some embodiments, two separate microcontrollers may be implemented, with one of the microcontrollers disposed on the fixed portion of the robot 108 and the other microcontroller disposed on the thickness mapping device 111.

[0022] The wireless connection facilitated by the RF front end and the antenna can, in some embodiments, support a communication link between the microcontroller and the computing device 118. In some embodiments, the microcontroller integrated with the robot 108 can have minimal computing capabilities sufficient to communicate information to the computing device 118 where most of the information processing can occur. In other embodiments, the microcontroller can perform a significant portion of the calculations, while the computing device 118 can provide computing support for specific, processing-intensive tasks. The data received by the computing device 118 can be data obtained from inside the transfer chamber 104, the processing chamber 106, data collected by the optical sensor 114, data temporarily or permanently stored in the memory buffer, and the like. The data stored in the memory buffer and / or sent to or from the computing device 118 can be in raw or processed format.

[0023] In one embodiment, the thickness mapping device can determine and output profile data characterizing the thickness variations of the substrate (using the processing capabilities of the microcontroller and / or the computing device 118) based on the intensity values associated with one or more received optical beams. The one or more received optical beams can be caused by the scanning of the substrate by one or more incident optical beams and the interaction with the substrate. The intensity values can be due to one or more locations of the substrate.

[0024] For example, the thickness mapping device 111 may scan a substrate with a first light beam from a (one or more) light source 112. The thickness mapping device 111 may obtain intensity values associated with a second light beam corresponding to one or more locations of the substrate. The second light beam may be caused by the interaction of the first light beam and the substrate. The interaction may include reflection or transmission of the first (incident) light beam with the substrate. Thus, the second light beam may be a reflected beam or a transmitted beam. The thickness mapping device 111 may use the obtained intensity values to determine profile data that characterizes thickness variations of the substrate. In some cases, during a processing stage of the substrate, such as deposition, etching, polishing, etc., a slurry (which may include beads of water and / or other materials used in the processing) that is harmful to the accuracy of optical measurements and thickness mapping may be formed. To remove residual water, in some embodiments, a directed gas source (e.g., a jet of gas), such as nitrogen, argon, xenon, air, etc., may be applied to dry the substrate prior to scanning with the light beam in order to minimize the optical effects of such foreign materials and ensure the accuracy of the determined profile data.

[0025] Multiple intensity values can be determined for a substrate. In some embodiments, when thickness mapping is performed using reflected light, the intensity values can represent the reflectivity of the substrate at various locations. In some embodiments, when thickness mapping is performed using transmitted light, the intensity values can represent the transmittance of the substrate at various locations. Since the light reflected from the top surface of the substrate and the light reflected from the bottom surface can interfere, the reflectivity and / or transmittance can exhibit a series of bright (maxima) and dark (minima) interference fringes. Such interference fringes can be used as a benchmark for determining the thickness (and / or thickness variation) of the substrate, as described in more detail below. In particular, the intensity values can include at least a first intensity value from a first location among one or more locations and a second intensity value from a second location among one or more locations. Profile data can use the first intensity value and the second intensity value to identify the thickness change of the substrate between the first location and the second location.

[0026] Since the reflectivity (and / or transmittance) can be a periodic function of the thickness of the substrate, in some cases there may be some ambiguity as to whether the thickness is increasing or decreasing between the first location and the second location. For example, for a given wavelength λ and angle of incidence θ, the intensity I = f(d; λ, θ) of the reflected (or transmitted) light beam can include several interference maxima and minima for the varying thickness d of the substrate. As a result, when the first intensity value determined at the first location, for example, I1 = f(d1; λ1, θ1), is close to the maximum (or minimum) value of the function f, a lower (or higher) second intensity value, for example, I2 = f(d2; λ1, θ1), may not sufficiently determine whether the thickness of the substrate is increasing (d2 > d1) or decreasing (d1 > d2) between the first location and the second location. In such cases, the thickness mapping device 111 may scan the substrate with an additional light beam (e.g., a third light beam) from one or more of the same or other light sources 112. The third light beam may be different from the first light beam by at least one of the wavelength (e.g., λ2) or the angle of incidence on the substrate (e.g., θ2). For example, in one embodiment, there may be two (or more) light sources 112, each source providing a light beam of a different wavelength. In another embodiment, there may be a single light source 112 that provides a light beam that is split (e.g., by a beam splitter), and each of the split beams may be incident on the substrate at a different angle. In some embodiments, the light beams incident on the substrate may have different wavelengths as well as different angles of incidence. In any case, the thickness mapping device 111 may obtain a second set of intensity values associated with at least some of one or more locations of the substrate. The fourth light beam may be caused by the interaction of the third light beam with the substrate and may be a reflected beam or a transmitted beam (similar to the second beam).To resolve possible ambiguities regarding whether the thickness is increasing or decreasing, the thickness mapping device may determine and output a profile based on both a first set of intensity values and a second set of intensity values, such as I3 = f(d1; λ2, θ2) and I4 = f(d2; λ2, θ2).

[0027] FIG. 2A shows a small spot scanning interferometer system 200 with a single light source 204 for mapping thickness variations of a substrate 202 according to one embodiment. The interferometer system 200 may include a light source 204, a detector 206, and a beam splitter 208. In some embodiments, the thickness variation mapping setup may include an optical head 212 that combines one or more of the light source 204, the detector 206, and the beam splitter 208. The substrate may be supported by lift pins 210. The pins 210 may be used for edge handling of the substrate 202. In some embodiments, the substrate may be a silicon carbide (SiC) wafer.

[0028] The substrate 202 may be irradiated by an incident beam 214 of light (or other forms of electromagnetic radiation), and a reflected beam 216 may be generated upon interaction of the incident beam 214 with the substrate. In some embodiments, the incident beam 214 may be a collimated beam, a focused beam, a coherent beam, a polarized beam, a pulsed beam, or some other light beam. The intensity of the reflected beam 216 may exhibit some bright and dark fringes (e.g., as a function of the substrate thickness) caused by constructive and destructive interference of multiple internal reflections of the beam within the substrate 202. When the incident beam 214 is moved relative to the substrate 202 (or the substrate 202 is transported relative to the incident beam 214), a small uniform variation in the thickness of the substrate may lead to a series of alternating fringe-peak and valley / troughs in the intensity of the reflected (or transmitted) beam.

[0029] The spatial frequency of the hills / valleys occurring in the interaction (e.g., the reciprocal of the horizontal distance between adjacent stripes) can be determined by the variation in the thickness of the substrate 202 (e.g., the tangent of the angle the surface makes with the horizontal direction), the wavelength of the incident light beam, and the angle of incidence of the light beam with respect to the substrate. Thus, by scanning the substrate 202 with a light beam at a known frequency and a known angle of incidence, the thickness profile of the substrate can be mapped. For example, the substrate 202 can be scanned in various ways. In one embodiment, the substrate 202 can be rotated and radially translated such that the entire surface of the substrate 202 is scanned in a spiral trace. In other embodiments, the substrate 202 can be fixed while the optical head 212 is rotated in a spiral pattern such that the entire surface of the substrate 202 is scanned. In other embodiments, the substrate 202 can be raster scanned by moving one or both of the substrate 202 or the optical head 212 in a rectangular pattern.

[0030] As shown in FIG. 2A, the optical head 212 can include a light source 204 that emits a light beam at a wavelength λ. The light beam can be split into a first light beam and a second light beam, each having a wavelength λ. The first light beam can be incident on the substrate 202 at a first angle of incidence and interact with the substrate 202. The first detector 206a can detect a first set of intensity values associated with a third light beam caused by the interaction of the first light beam with the substrate 202. Each intensity value can be associated with a set of locations on the substrate 202 according to a selected scan pattern (e.g., spiral, rectangular, etc.). Similarly, the second light beam can be incident on the substrate 202 at a second angle of incidence and interact with the substrate 202. The second detector 206b can detect a second set of intensity values associated with a fourth light beam caused by the interaction of the third light beam with the substrate 202. Each intensity value can be associated with one of a set of locations on the substrate 202 according to the selected scan pattern. The first set of intensity values and / or the second set of intensity values can then be used to determine the thickness profile data of the substrate 202.

[0031] In some embodiments where light reflected from substrate 202 is detected, absorber 218 may be positioned opposite (e.g., below) substrate 202 to prevent (or minimize) light transmitted through the substrate from reflecting back to the substrate and affecting the substrate reflectivity data acquired by detectors 206a and 206b. Absorber 218 may include a special anti - reflective material to prevent light from interacting with the underlying substrate support. Additionally or alternatively, the back side of the substrate may include a special anti - reflective material to prevent light from interacting with the underlying substrate support.

[0032] FIG. 2B shows a small - spot scanning interferometer system 200 with two light sources 204a and 204b for mapping thickness variations of substrate 202 according to one embodiment. The small - spot scanning interferometer system 200 of FIG. 2B may be similar to the small - spot scanning interferometer system 200 of FIG. 2A, but may have an optical head that includes a plurality (two or more) of light sources.

[0033] As shown in FIG. 2B, optical head 212 may include a first source of light 204a and a second light source 204b that emit light beams having a first wavelength λ1 and a second wavelength λ2. The first light beam may be incident on substrate 202 at a given angle of incidence (e.g., the normal angle or some other small angle) and interact with substrate 202. The first detector 206a may detect a first set of intensity values associated with a third light beam caused by the interaction of the first light beam with substrate 202. Each intensity value may be associated with one of a set of locations on substrate 202 according to a scanning pattern. Similarly, the second light beam may be incident on substrate 202 at a given angle of incidence and interact with substrate 202. The second detector 206b may detect a second set of intensity values associated with a fourth light beam caused by the interaction of the second light beam with substrate 202. Each intensity value may be associated with a set of locations on substrate 202 according to the scan. The first set of intensity values and the second set of intensity values may be used to determine the thickness profile data of substrate 202.

[0034] FIG. 2C shows a small-spot scanning interferometer system 201 with a single light source 204 and a movable mirror for mapping thickness variations of a substrate 202 according to one embodiment. The small-spot scanning interferometer system 201 can be similar to the small-spot scanning interferometer system 200 of FIGS. 2A-2B as described by like reference numerals. As shown in FIG. 2C, a light beam from the light source 204 can be directed toward the beam splitter 208. The beam splitter 208 splits the light beam into a first incident light beam 214a and a second incident light beam 214b. The first incident light beam 214a can be incident on the substrate 202 (e.g., a sample) at a first incident angle. The second incident light beam 214a with respect to the sample can be directed toward the sample by the mirror 220. The mirror 220 can be tilted by an angle for setting a second incident angle of the second incident light beam 214b with respect to the sample. In some embodiments, the mirror 220 can be mounted on a tilting stage, and thus, a change in tilt can change the incident angle of the second light beam 214a. Referring to Equation (2) (introduced below), from Snell's law, the internal reflection angle β is related to the incident angle α with respect to the sample. nsinβ = sinα

[0035] Therefore, a slight change in α will result in a change in the internal reflection angle. This will cause a shift in the position of the fringes, as per Equation (1) (introduced below). Therefore, the position of the fringes can be adjusted or changed by varying the incident angle very slightly. Such a small change to the incident angle will result in a negligible change to the position of the beam on substrate 202. This enables the ability to resolve the ambiguity of the thickness variation. For example, if the thickness variation of substrate 202 is such that the signals in the thickness plateau region (i.e., the locations where the signal does not vary as a function of the position on the sample) are at the maximum or minimum for both incident angles, then by slightly shifting the incident angle of one of the beams, the simultaneity of the two signals that are at the maximum or minimum is broken, and thus the ambiguity condition is resolved. A slight change in the incident angle can be easily achieved, for example, by using a piezo-mounted mirror.

[0036] In some embodiments, the small spot scanning interferometer systems 200 and 201 can be combined with a mass measurement system to perform cross-verification of the deposition process and the etching process. For example, the mass measurement system can provide information regarding the total mass change of the substrate due to the processing operation (without providing spatial information), and the thickness variation profile can indicate regions of non-uniform thickness due to the processing operation. In such a manner, determining the thickness variation profile can be used as a feed-forward or feedback mechanism for an additive or subtractive process.

[0037] FIG. 3 schematically shows the intensity values and interference fringes for a scan using two optical beams over a region of a substrate having thickness variations, according to one embodiment. Assuming that the substrate is irradiated from above by coherent, collimated radiation, the reflection response can appear as several parallel fringes.

[0038] For example, the fringe intensity can be given by TIFF0007695465000001.tif28170, where TIFF0007695465000002.tif17170, where β is the angle of internal reflection with respect to the surface normal, h(x, y) is the local thickness, λ is the wavelength of light in vacuum, I0 is the intensity of the light incident on the substrate, n is the refractive index of the material, and r 2 is the surface reflectivity.

[0039] For a given light beam, the spatial frequency of the interference fringes can be determined by the slope of the thickness variation, the angle of incidence, and the wavelength. For example, dark fringes in reflectivity can be encountered at points (x, y) on the substrate where θ = 0, 2π, 4π,.... Thus, different dark fringes in reflectivity can correspond to locations on the substrate where the thickness differs by an integer multiple of Δh = λ / (2n·cosβ). Correspondingly, the maxima in reflectivity are encountered at locations where the substrate thickness differs by ±Δh / 2 from the thickness at locations where the reflectivity has a dark fringe (minimum). Thus, the substrate can be scanned by a first (incident) light beam, and a second (reflected or transmitted) light beam corresponding to the interaction of the first light beam with the substrate can be detected. A first set of intensity values associated with the second light beam and corresponding to various locations on the substrate can be obtained (e.g., using detector 206). The first set of intensity values can be used to determine profile data characterizing the thickness variation h(x, y) of the substrate.

[0040] In particular, the intensity values can include a first intensity value I(x1, y1) for a first location and a second intensity value I(x2, y2) for a second location. The first intensity value and the second intensity value can be used to determine the change in thickness Δh of the substrate between the first location and the second location. However, as explained above, in some cases, particularly when the reflection (or transmission) in the plateau is close to a maximum or minimum value, there may be some ambiguity regarding whether the thickness is increasing or decreasing after the plateau.

[0041] Platoons can be identified based on subsets of the first set of intensity values being equal. It should be understood that two substrate thicknesses h1 and h2 can still be considered equal if the difference |h1 - h2| < δh is within the target accuracy δh. The target accuracy δh can refer to the desired accuracy of the manufacturing process. In some embodiments, the target accuracy δh can refer to the resolution of the optical inspection system. For example, if the resolution of the optical inspection system is δh r then locations where |h1 - h2| < δh r can be considered to have equal thicknesses.

[0042] In some cases, platoons of equal thickness (in the above sense) can be near a particular thickness where the reflectivity or transmittance has a maximum or minimum value. As the thickness changes, the reflectivity or transmittance can decrease or increase, respectively, regardless of whether the substrate thickness is increasing or decreasing. To resolve such ambiguity, additional scans can be performed with additional beams having different incident angles and / or different wavelengths. Generally, even if the reflectivity or transmittance of the first beam is at a peak or trough on the platoon, the additional beam (if the additional beam has different incident angles and / or wavelengths) will not be near its maximum or minimum value. The additional beam can thus serve as an ambiguity removal benchmark for comparing the reflectivity / transmittance of the first beam.

[0043] More specifically, the substrate can be scanned by an additional light beam (e.g., a third light beam). The third light beam can be different from the first light beam at least in one of the wavelength λ2 or the incident angle θ2 with respect to the substrate. A fourth light beam corresponding to the interaction between the third light beam and the substrate can be detected. A second set of intensity values corresponding to various locations on the substrate associated with the fourth light beam can be obtained. The second set of intensity values can be used to further determine profile data characterizing thickness variations of the substrate. Since the first light beam and the third light beam have different wavelengths and / or incident angles (leading to different internal reflection angles), the intensity fringes generated by the first light beam and the third light beam are different. This provides the ability to remove the ambiguity of whether the thickness is increasing or decreasing following the scan of the plateau.

[0044] For example, when scanning is performed in the direction of increasing thickness, the maxima or minima of the intensity of the second beam (e.g., reflected λ1,θ1 light) are encountered at a different (spatial) frequency than the maxima and minima of the intensity of the fourth beam (e.g., reflected λ2,θ2 light). As shown in FIG. 3, in the first region 303 with a positive slope, the interference fringes 301 (solid line) resulting from the scanning by the first light beam are shifted to the left with respect to the interference fringes 302 (dashed line) resulting from the scanning by the third light beam. In the second region 305, the slope is 0 (plateau region), and the intensity remains uniform for both beams. In the third region 307, the slope is negative, and the relative spatial order between the interference fringes 301 and 302 is reversed (the interference fringes 301 are shifted to the right). For example, the interference fringes 313 and 315 exhibit opposite slopes due to the reversal of the relative order of the fringes from the scanning by the first and third light beams. In the fifth region 311, after passing through another plateau in the fourth region 309, the slope is again positive, and the relative spatial order between the interference fringes 301 and 302 is reversed compared to the third region 307. As shown, the interference fringes 317 and 319 exhibit opposite slopes due to the reversal of the relative order of the fringes from the scanning by the first and third light beams. Similarly, the interference fringes 313 and 319 have the same relative order indicating that the slopes in the first region 303 and the fifth region 311 are the same (e.g., positive).

[0045] Figure 4 shows the integration with optical inspection measurement of a machine learning method for manufacturing process control according to one embodiment. A substrate 202 being processed by a process tool 410 that can be a CMP (or some other polishing device) is shown in Figure 4. A measurement device, such as an optical head 212 (or some other measurement device), can monitor the real-time state of the substrate 202. For example, the optical head 212 can determine the thickness and profile of the substrate 202 while the process tool 410 changes the state of the substrate, for example, by removing material from the substrate 202. The profile data 420 output by the optical head 212 can be processed by one or more machine learning models 430 (MLM). The MLM 430 can be or include a decision tree algorithm, a support vector machine, a deep neural network, or any combination thereof. The deep neural network can include a convolutional neural network, a recurrent neural network (RNN) with one or more hidden layers, a fully connected neural network, a long short-term memory neural network, a Boltzmann machine, etc. The MLM 430 can be trained to perform a specific technology process, including a specific substrate profile to be created over a specific time, a specific quality of the surface of the substrate to be achieved, etc. The MLM 430 can use, as inputs, the profile data 420, the specifications of the technology process (not shown), the current timestamp (counted from the beginning of the technology process, for example), and other suitable data. The MLM 430 can output (for example, in real time) a tool setting 440 for the process tool 410. The tool setting can include the pressure applied by the process tool 410 to the substrate 202, the rate of material removal from the substrate 202, the speed of rotation of the process tool 410, or any other applicable tool setting 440. As the processing by the process tool 410 continues, the tool setting 440 can change accordingly. For example, when approaching the target profile, the MLM 430 can output a tool setting 440 that performs actions such as reducing the rate of material removal and reducing the pressure on the substrate.

[0046] In some embodiments, a measurement device (e.g., optical head 212) continuously monitors the state of substrate 202 (e.g., by moving over substrate 202 in a predetermined pattern). In some embodiments, the measurement device may periodically monitor the state of substrate 202, such as at specific times.

[0047] MLM 430 can be trained by MLM training engine 450. The training engine 450 can be located on the same manufacturing machine that hosts process tool 410 and the measurement device, or on several external servers communicatively coupled to the manufacturing machine. In some embodiments, the MLM training engine 450 can be located on a server that does not interact with the manufacturing machine, and the trained MLM is installed on the manufacturing machine after the training is performed. The MLM training engine 450 can use training data 460 that may include data related to substrates of a similar type and processed in a similar (or the same) technology process. For example, the training data 460 can include dynamic profile data, as well as tool settings performed during previous processing of similar wafers. The training data 460 can further include annotations indicating correct and incorrect processing. In some embodiments, the MLM training engine 450 can train MLM 430 in real time on the same manufacturing machine using, for example, self-directed training iteration for a single (or multiple) batch of substrates.

[0048] FIG. 5 is a flow diagram of a method 500 for mapping the thickness of a substrate according to one embodiment. Method 500 may be implemented using the systems and components shown in FIGS. 1 and 2A-2B or any combination thereof. Method 500 may be implemented using a single optical sensor or a plurality of optical sensors. The optical sensor(s) may be configured to scan the substrate shown in FIGS. 2A-2B. Some or all of the blocks of method 500 may, in some embodiments, be implemented in response to instructions from computing device 118 or microcontroller 152. Microcontroller 152 may include one or more processing devices such as a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a network processor, etc. The (one or more) processing devices may be communicatively coupled to one or more memory devices such as read only memory (ROM), flash memory, static memory, dynamic random access memory (DRAM), etc. Microcontroller 152 may be part of a desktop computer, a laptop computer, a workstation, a wearable device (e.g., a tablet, a smartphone, etc.), a cloud-based computing service, etc. In some embodiments, microcontroller 152 is part of a larger network of computing devices. In some embodiments, an external computing device communicating with microcontroller 152 is capable of reconfiguring microcontroller 152 (e.g., changing settings, updating memory, or reprogramming in some cases). In some embodiments, thickness mapping method 500 may be implemented while the wafer is present inside the processing chamber. In some embodiments, method 500 may be implemented when the wafer is removed from the processing chamber. The thickness mapping method may be implemented under conditions similar to the actual conditions of the processing chamber during the manufacturing process (e.g., in terms of pressure and temperature). Thus, the manufacturing process may be performed at a low temperature, or at a temperature below or significantly below room temperature.Alternatively, the manufacturing process can be performed at room temperature, above room temperature, or significantly above room temperature. In some embodiments, the pressure inside the chamber can be below or significantly below atmospheric pressure, which includes low vacuum or high vacuum conditions.

[0049] Method 500 can include scanning a substrate with a first light beam (block 502). The first light beam can be emitted from a laser, a narrowband light source, a broadband light source whose spectral distribution is later narrowed, a spectrally narrowed light emitting diode, etc. The first light beam can have a first wavelength and can be incident on the substrate at a first angle. Scanning the substrate can include moving the first light beam relative to the substrate. In some embodiments, the light source (and the photodetector) is fixed (e.g., relative to the substrate processing system), but the substrate is moving. For example, the substrate can be transported under the light source (and the photodetector) while the scanning is being performed. In some embodiments, the first light beam is moved relative to the substrate in a spiral pattern. In some embodiments, the first light beam is moved relative to the substrate in a rectangular pattern, a zigzag pattern, or any other geometric pattern.

[0050] Method 500 may continue to obtain, for each of a set of locations of a substrate, one of each of a first set of intensity values associated with a second light beam (block 504). The second light beam may be caused by an interaction between the first light beam and the substrate. The first set of intensity values associated with the second light beam may include at least a first intensity value for a first location of the set of locations and a second intensity value for a second location of the set of locations. In one embodiment, the second light beam is a reflected beam caused by an interaction between the first light beam and the substrate, and each of the first set of intensity values is related to the reflectivity of the substrate at each respective location of the set of locations of the substrate. In another embodiment, the second light beam is a transmitted beam caused by an interaction between the first light beam and the substrate, and each of the first set of intensity values is related to the transmittance of the substrate at each respective location of the set of locations of the substrate.

[0051] Method 500 may continue to determine profile data characterizing variations in the thickness of the substrate (block 506). Determining the profile data may be based on using the first set of intensity values, and may correspond to determining a change in the thickness of the substrate between the first location and the second location using the first intensity value and the second intensity value, and method 500 ends.

[0052] In further embodiments, method 500 may further include scanning the substrate with a third light beam. The third light beam may be different from the first light beam at least in terms of wavelength or the angle of incidence of the light beam on the substrate. In further embodiments, method 500 may further include obtaining, for at least some of the locations of the substrate, one of each of a second plurality of intensity values associated with a fourth light beam. The fourth light beam may be caused by an interaction between the third light beam and the substrate, and determining the profile data may be further based on the second set of intensity values.

[0053] The second set of intensity values associated with the fourth beam can identify a third group of interference fringes for a first region of the substrate and a fourth group of interference fringes for a second region of the substrate. In some embodiments, determining the profile data further includes identifying that the relative spatial order of the first group of interference fringes and the third group of interference fringes is different from the relative spatial order of the second group of interference fringes and the fourth group of interference fringes. Using the identified relative spatial order of the interference fringes, it can be determined that the thickness of the substrate is increasing in the direction of scanning (e.g., in the first region) and decreasing in the direction of scanning (e.g., in the second region), or vice versa.

[0054] Scanning the substrate can include moving at least one of the first light beam or the third light beam in a spiral pattern with respect to the substrate. In other embodiments, scanning the substrate can include moving the substrate in a spiral pattern with respect to at least one of the first light beam or the third light beam. In some embodiments, scanning the substrate can include scanning in a pattern other than a spiral, for example, in a raster scan pattern.

[0055] In some embodiments, if it is determined that a subset of the first set of intensity values is substantially equal (e.g., equal within a target accuracy value), it can be determined that the thickness of the region of the substrate is uniform.

[0056] In some embodiments, for example, CMP residual water can remain on the substrate. To improve the accuracy of thickness mapping, a portion of the substrate can be dried (or cleaned) by a flow of gas (such as nitrogen, argon, xenon, air, etc.) prior to scanning.

[0057] In some embodiments, the thickness of the substrate can be modified (e.g., increased by additional deposition by a deposition device or decreased (e.g., etched using an etching device or polished using a polishing device)) or optionally adjusted in view of determined thickness profile data. In some embodiments, the substrate is a SiC wafer that can be adjusted by varying device control parameters. The control parameters can determine the rate or amount of material added to (or removed from) the substrate.

[0058] The systems and methods disclosed herein can be used not only for monitoring thickness variations during manufacturing, but also for testing and development of various deposition and polishing processes. The advantages of the disclosed embodiments include, but are not limited to, the ability to inspect process quality and substrate surface uniformity, among others.

[0059] FIG. 6 shows a block diagram of an exemplary processing device 600 that operates in accordance with one or more aspects of the present disclosure. The processing device 600 can be the computing device 118 of FIG. 1.

[0060] The exemplary processing device 600 can be connected to other processing devices in a local area network (LAN), intranet, extranet, and / or the Internet. The processing device 600 can be a personal computer (PC), set-top box (STB), server, network router, switch or bridge, or any device capable of executing a set (serial or otherwise) of instructions that specify actions to be taken by that device. Further, although only a single exemplary processing device is shown, the term "processing device" is also to be construed as including any collection of processing devices (e.g., computers) that individually or together execute a set (or multiple sets) of instructions to perform any one or more of the methods described herein.

[0061] Exemplary processing device 600 may include a processor 602 (e.g., a CPU), a main memory 604 (e.g., a dynamic random access memory (DRAM) such as a read-only memory (ROM), a flash memory, a synchronous DRAM (SDRAM), etc.), a static memory 606 (e.g., a flash memory, a static random access memory (SRAM), etc.), and a secondary memory (e.g., data storage device 618), which can communicate with each other via bus 630.

[0062] Processor 602 represents one or more general-purpose processing devices, such as a microprocessor, a central processing unit, etc. More specifically, processor 602 can be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing a combination of instruction sets. Processor 602 can also be one or more dedicated processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a network processor, etc. According to one or more aspects of the present disclosure, processor 602 can be configured to execute instructions for implementing method 500 of thickness variation mapping.

[0063] Exemplary processing device 600 may further include a network interface device 608 that can be communicatively coupled to network 620. Exemplary processing device 600 may further include a video display 610 (e.g., a liquid crystal display (LCD), a touch screen, or a cathode ray tube (CRT)), an alphanumeric input device 612 (e.g., a keyboard), an input control device 614 (e.g., a cursor control device, a touch screen control device, a mouse), and a signal generation device 616 (e.g., an acoustic speaker).

[0064] The data storage device 618 may include a computer-readable storage medium (or, more particularly, a non-transitory computer-readable storage medium) 628 in which one or more sets of executable instructions 622 are stored. According to one or more aspects of the present disclosure, the executable instructions 622 may include executable instructions for implementing the method 500 of thickness variation mapping.

[0065] The executable instructions 622 may also be present, in whole or at least in part, within the main memory 604 and / or within the processor 602 during the execution of the executable instructions 622 by the exemplary processing device 600, and the main memory 604 and the processor 602 also constitute a computer-readable storage medium. The executable instructions 622 may further be transmitted or received over a network via the network interface device 608.

[0066] The computer-readable storage medium 628 is shown in FIG. 6 as a single medium, but the term "computer-readable storage medium" is to be construed to include a single medium or a plurality of media (e.g., a centralized or distributed database and / or associated cache and servers) that store one or more sets of operating instructions. The term "computer-readable storage medium" is also to be construed to include any medium that is capable of storing or encoding a set of instructions for machine execution and that causes a machine to perform any one or more of the methods described herein. The term "computer-readable storage medium" is thus to be construed to include, without limitation, solid state memory and optical and magnetic media.

[0067] It should be understood that the above description is illustrative and not restrictive. Many other embodiments will be apparent to those of ordinary skill in the art upon reading and understanding the above description. While the present disclosure has been described with respect to specific examples, it will be recognized that the systems and methods of the present disclosure are not limited to the examples described herein, but may be practiced with modifications within the scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. Therefore, the scope of the present disclosure should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0068] The method, hardware, software, firmware, or code embodiments described above may be implemented via instructions or code stored on a machine-accessible medium, machine-readable medium, computer-accessible medium, or computer-readable medium that is executable by a processing element. "Memory" includes any mechanism that provides information (i.e., stores and / or transmits) in a form readable by a machine, such as a computer or an electronic system. For example, "memory" includes random access memory (RAM), such as static RAM (SRAM) or dynamic RAM (DRAM), ROM, magnetic or optical storage media, flash memory devices, electrical storage devices, optical storage devices, acoustic storage devices, and any type of tangible machine-readable medium suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0069] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0070] In the foregoing specification, detailed description has been given with reference to specific exemplary embodiments. However, it will be apparent that various modifications and changes may be made thereto without departing from the broader spirit and scope of the disclosure as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a limiting sense. Further, the above use of the term "embodiment" and / or other exemplary language does not necessarily refer to the same embodiment or the same example, and may refer to different and distinct embodiments, as well as potentially the same embodiment.

[0071] The words "example" or "exemplary" are used herein to mean an example, instance, or illustration. Any aspect or design described herein as an "example" or "exemplary" should not necessarily be construed as preferred or advantageous over other aspects or designs. Rather, the use of the words "example" or "exemplary" is intended to present concepts in a concrete manner. The term "or" as used herein means an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X includes A or B" is intended to mean any of the natural inclusive permutations. That is, "X includes A or B" is satisfied under any of the above cases where X includes A, X includes B, or X includes both A and B. Further, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless otherwise specified or clear from the context that the singular form is intended. Moreover, the use of the term "an embodiment" or "one embodiment" throughout does not mean the same embodiment or example unless so described as such. Also, the terms "first", "second", "third", "fourth", etc. as used herein are meant as labels to distinguish different elements and do not necessarily have the meaning of an order based on their numerical representation.

Claims

1. Scanning a substrate with a first light beam; For each of a plurality of locations on the substrate, obtaining one of a first plurality of intensity values associated with a second light beam, wherein the second light beam is caused by an interaction between the first light beam and the substrate, and obtaining one of the first plurality of intensity values; Scanning the substrate with a third light beam, wherein the third light beam is different from the first light beam in at least one of wavelength or incident angle with respect to the substrate, and scanning the substrate with the third light beam; For at least some of the plurality of locations on the substrate, obtaining one of a second plurality of intensity values associated with a fourth light beam, wherein the fourth light beam is caused by an interaction between the third light beam and the substrate, and obtaining one of the second plurality of intensity values; Using the first plurality of intensity values and the second plurality of intensity values to determine profile data characterizing thickness variations of the substrate; comprising the first plurality of intensity values being a first group of interference fringes for a first region of the substrate, and a second group of interference fringes for a second region of the substrate and identifying; the second plurality of intensity values being a third group of interference fringes for the first region of the substrate, and a fourth group of interference fringes for the second region of the substrate and identifying; determining the profile data comprises identifying that a relative spatial order of the first group of interference fringes and the third group of interference fringes is different from a relative spatial order of the second group of interference fringes and the fourth group of interference fringes; Based on the identifying, the thickness of the substrate is increasing in the scanning direction in the first region, and decreasing in the scanning direction in the second region, determining and a method including the above. **Claim 2** The plurality of first intensity values related to the second light beam are a first intensity value for a first location among the plurality of locations, and a second intensity value for a second location among the plurality of locations, including determining the profile data is using the first intensity value and the second intensity value to determine a change in the thickness of the substrate between the first location and the second location The method according to claim 1, including the above. **Claim 3** Scanning the substrate includes moving at least one of the first light beam or the third light beam in a spiral pattern with respect to the substrate. The method according to claim 1. **Claim 4** The second light beam is a reflected beam caused by the interaction between the first light beam and the substrate, and each of the plurality of first intensity values is related to the reflectivity of the substrate at each of the plurality of locations of the substrate. The method according to claim 1. **Claim 5** The second light beam is a transmitted beam caused by the interaction between the first light beam and the substrate, and each of the plurality of first intensity values is related to the transmittance of the substrate at each of the plurality of locations of the substrate. The method according to claim 1. **Claim 6** further comprising determining that the thickness of the region of the substrate is uniform based on a subset of the first plurality of intensity values that are equal within a target accuracy, each of the subset of the first plurality of intensity values being obtained for the region of the substrate, the method of claim 1.

7. before scanning the substrate with the first light beam further comprising drying at least a portion of the substrate with a gas flow, the method of claim 1.

8. modifying the thickness of the substrate in at least one region of the substrate in view of the determined profile data further comprising the method of claim 1.

9. the method of claim 1, wherein the substrate is a silicon carbide (SiC) wafer.

10. A system configured to scan a substrate, the system comprising: a first light source for emitting a first light beam; a first light sensor for obtaining, for each of a plurality of locations of the substrate, one of the first plurality of intensity values associated with a second light beam, the second light beam being caused by an interaction between the first light beam and the substrate; a second light source for emitting a third light beam for scanning a first region and a second region of the substrate, the third light beam being different from the first light beam in the angle of incidence on the substrate; a second light sensor for obtaining, for at least some of the plurality of locations of the substrate, one of the second plurality of intensity values associated with a fourth light beam, the fourth light beam being caused by an interaction between the third light beam and the substrate; A processing device for determining profile data characterizing fluctuations in the thickness of the substrate using the plurality of first intensity values and the plurality of second intensity values, comprising, wherein the plurality of first intensity values include a first group of interference fringes for a first region of the substrate and a second group of interference fringes for a second region of the substrate, and identify, wherein the plurality of second intensity values include a third group of interference fringes for the first region of the substrate and a fourth group of interference fringes for the second region of the substrate, and identify, determining the profile data includes identifying that the relative spatial order of the first group of interference fringes and the third group of interference fringes is different from the relative spatial order of the second group of interference fringes and the fourth group of interference fringes, and based on the identifying, determining that the thickness of the substrate is increasing in the scanning direction in the first region, and is decreasing in the scanning direction in the second region, and including, a system. **Claim 11** The system according to claim 10, further comprising a beam splitter, wherein the second light source and the first light source are the same, and an incident angle of the third light beam on the substrate is different from an incident angle of the first light beam on the substrate. **Claim 12** The system according to claim 10, wherein the second light source is different from the first light source, and a wavelength of the third light beam is different from a wavelength of the first light beam. **Claim 13** The system according to claim 10, wherein the first light source and the first optical sensor are mounted on an optical head, and the first light beam is moved relative to the substrate by moving at least one of the substrate or the optical head in order to scan the substrate.

14. The system according to claim 10, further comprising a directional gas source for drying at least a portion of the substrate by a gas flow.

15. The system according to claim 10, further comprising a substrate processing tool configured to modify the thickness of the substrate, wherein the processing device is further for applying a machine learning model to the first plurality of intensity values to determine an adjusted tool setting for the substrate processing tool.

16. A movable stage for supporting a substrate, A first light source for directing a first light beam to scan the substrate being transported on the movable stage, A first optical sensor for obtaining, for each of a plurality of locations of the substrate, one of the first plurality of intensity values associated with a second light beam, the second light beam being caused by an interaction between the first light beam and the substrate, A second light source for emitting a third light beam to scan the substrate, the third light beam being different from the first light beam in at least one of wavelength or angle of incidence on the substrate, A second optical sensor for obtaining, for at least some of the plurality of locations of the substrate, one of the second plurality of intensity values associated with a fourth light beam, the fourth light beam being caused by an interaction between the third light beam and the substrate, A processing device communicatively coupled to the first optical sensor and the second optical sensor for generating profile data characterizing variations in the thickness of the substrate using the first plurality of intensity values and the second plurality of intensity values comprising wherein the first plurality of intensity values identify a first group of interference fringes for a first region of the substrate, and a second group of interference fringes for a second region of the substrate and the second plurality of intensity values identify a third group of interference fringes for the first region of the substrate, and a fourth group of interference fringes for the second region of the substrate and generating the profile data includes identifying that a relative spatial order of the first group of interference fringes and the third group of interference fringes is different from a relative spatial order of the second group of interference fringes and the fourth group of interference fringes, and based on the identifying, determining that the thickness of the substrate is increasing in the scanning direction in the first region and is decreasing in the scanning direction in the second region and a system comprising determining and a system comprising

17. The system of claim 16, further comprising at least one of a deposition device, an etching device, or a polishing device configured to adjust the thickness of at least one of the plurality of locations of the substrate based on the profile data.

18. The system of claim 17, wherein at least one device control parameter of the deposition device, the etching device, or the polishing device is controlled to adjust the thickness of the substrate. Claim 19 The system according to claim 17, wherein the polishing device is a chemical mechanical polishing (CMP) device. Claim 20 The system according to claim 16, wherein the movable stage comprises at least one of i) a robotic blade or ii) a polishing device capable of adjusting the thickness of at least one of the plurality of locations of the substrate.

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