Patent Publication Number: US-2021172728-A1

Title: Methods and systems of optical inspection of electronic device manufacturing machines

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/944,599, filed Dec. 6, 2019, the entire contents of which are hereby incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     This instant specification generally relates to ensuring quality control of systems used in electronic device manufacturing, such as deposition chambers. More specifically, the instant specification relates to optical inspection of various components of electronic device manufacturing machines as well as optical inspection of a correct alignment of such components relative to each other and to wafers. 
     BACKGROUND 
     Manufacturing of modern materials often involves various deposition techniques, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques, in which atoms of one or more selected types are deposited on a substrate (wafer) held in low or high vacuum environments that are provided by vacuum deposition chambers. Materials manufactured in this manner may include monocrystals, semiconductor films, fine coatings, and numerous other substances used in practical applications, such as electronic device manufacturing. Many of these applications depend critically on the purity of the materials grown in the deposition chambers. The need to maintain isolation of the inter-chamber environment and to minimize its exposure to ambient atmosphere and contaminants therein gives rise to various robotic techniques of sample manipulation and chamber inspection. Improving precision, reliability, and efficiency of such robotic techniques presents a number of technological challenges whose successful resolution is crucial for continuing progress of electronic device manufacturing. This is especially important given that the demands to the quality of chamber manufacturing products are constantly increasing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates one exemplary implementation of a manufacturing machine capable of supporting optical inspection of targets therein. 
         FIG. 1B  illustrates the electronics module capable of facilitating optical inspection of targets inside the manufacturing machine, in one exemplary implementation. 
         FIG. 2  illustrates an inspection device setup for performing optical inspection of targets and target surfaces within electronic device manufacturing machines, in one exemplary implementation. 
         FIG. 3A  illustrates an inspection device setup for performing optical inspection of the surface of the edge ring, in one exemplary implementation. 
         FIG. 3B  illustrates an inspection device setup for clearance measurements in processing chambers, in one exemplary implementation. 
         FIG. 4  illustrates inspection data obtained using the inspection device setup of  FIG. 3A  for performing optical inspection of the surface of the edge ring, in one exemplary implementation. 
         FIG. 5  illustrates an inspection device setup for performing horizontal optical inspection of the surface of the edge ring, in one exemplary implementation. 
         FIG. 6A  illustrates an inspection device setup for performing optical inspection of a gap between the chuck and the edge ring (“chuck-to-edge ring gap”), in one exemplary implementation. 
         FIG. 6B  illustrates an inspection device setup for performing optical inspection of a spacing between the wafer and the edge ring (“wafer-to-edge ring gap” or “pocket gap”), in one exemplary implementation. 
         FIG. 7  is a flow diagram of one possible implementation of a method of optical inspection of manufacturing device chambers and components. 
         FIG. 8  depicts a block diagram of an example processing system capable of supporting real-time detection of particulate contaminants present inside a deposition chamber, based on light scattering data. 
     
    
    
     DETAILED DESCRIPTION 
     The implementations disclosed herein provide for contactless optical inspection with the help of light sensors of various target surfaces inside processing chambers (that may include deposition chambers, etching chambers, and so on) and alignment of various physical components (both tools and products) present inside deposition chambers. For example, the implementations disclosed may help determine an extent of deterioration of various tools used for wafer handling during manufacturing (e.g., edge rings, electrostatic chucks) and relative alignment of components (e.g., relative positioning of edge rings to chucks, wafers to chucks, wafers to edge rings, and so on). 
     The robotic systems require accurate calibration to be performed to set precise alignment of various components of the manufacturing process. Calibration may be required during initial installation and setup as well as for various after-installation purposes, such as maintenance, quality control, modifications of the setup, and for other reasons. In some instances, equipment (or some parts of it) may experience wear and may need to be replaced once its performance drops below a required level. 
     For some manufacturing equipment, such as semiconductor manufacturing chambers, it may be both time-consuming and expensive to completely or partially shut-down the equipment and the manufacturing process to perform maintenance, recalibration, and/or inspection of the equipment. Conventional methods of performing calibrations may be performed by taking the equipment off-line from normal manufacturing operations. This may require removing process gases, altering voltages, magnetic field, in-chamber pressure and/or temperature, opening the chamber, manually performing calibrations, etc. For example, a person conducting maintenance may open a lid of the chamber, place a pin or jig into a component of the processing chamber—and then manually perform calibrations between the robot handling system and the processing chamber. After calibrations have been completed, the pin or jig is physically removed, the lid of the processing chamber is closed and the processing chamber is returned on-line. 
     Alternatively, to minimize the time and expense of taking manufacturing equipment off-line, a disc-shaped calibrating device in the form of a wafer may be introduced into the chamber. For example, a robot can load and unload the calibrating device into the chamber. Handling the calibrating device in a precise manner may require camera technology to verify accurate alignment to various types of targets found in the manufacturing equipment. A different approach may be based on precise sensing of the start points and end points of the motion of the calibrating device and the relation of the start/end points to a target. This may be achieved by using sensors located on the calibrating device. This method may include determining (e.g., calculating) a center and/or orientation of the target based on the start points and the end points. 
     Precise positioning of the calibrating device relative to a target may be in some instances hindered by target wear, for example from routine manufacturing. For example, during manufacturing process, a wafer (substrate) may be placed on a wafer receiving surface and carried (e.g., by lift pins) into a region where the wafer may be subjected to a flow of deposition particles, and/or a gas or plasma used to facilitate deposition. An edge ring—often referred to as a process kit—may be used to illuminate the wafer and increase its temperature. For example, the edge ring may be located at the same level as the wafer receiving surface, so that when the wafer is lifted above the receiving surface, the wafer is also lifted above the edge ring as well. The edge ring may have an inner radius that is slightly greater than an outer radius of the wafer, so that a small gap remains between the wafer and the edge ring. A light source may illuminate a surface (e.g., a bottom surface) of the edge ring, and the surface of the edge ring may redirect (reflect) the light from the light source onto a surface (e.g., the bottom surface of the wafer). The edge ring may have a surface that is cut in a precise way so to optimize the performance of the edge ring. For example, the edge ring may have one or more recesses, ridges, flat regions designed for more efficient (e.g., uniform or, if needed, non-uniform with a particular directional dependence) illumination of the wafer. 
     With time and exposure to elevated temperatures, chemicals, light, and other environmental components of the inside of the chamber, the surface of the edge ring may deteriorate and the performance of the edge ring may suffer. Existing methods of robotic calibration of the tools and components of the processing chamber do not provide for examination of the surfaces of the edge rings and other target surfaces (e.g., wafer receiving surface, electrostatic chuck surface, lift pins&#39; surfaces, and so on) while the processing chamber is in the manufacturing mode. At present, taking the processing chamber off the production line, draining it of the gases and other chemicals, opening the lid, and directly examining the target components is necessary. This may be very costly and inefficient. An operator may not be able to estimate when the target component has deteriorated to an extent that calls for its replacement. For example, in some instances, an operator may interrupt manufacturing and examine the target component only to find out that the target component is in an acceptable state and does not require a replacement. In other instances, overestimating the lifespan of the target component may result in the target component not being replaced for a substantial time after the target component has started delivering inadequate performance. For these reasons, it is desirable for chamber operators to have an inspection method (and corresponding tools) that would allow a quick and efficient way of verifying the conditions of various components of the processing chamber without taking the chamber off the manufacturing line. 
     Aspects and implementations of the present disclosure address this and other shortcomings of the existing technology. Described herein is an optical inspection tool capable of implementing inspection of various targets inside a processing chamber without taking the chamber off the production line. The optical inspection tool may be equipped with light sources and light sensors to detect light emitted by the light sources and reflected off a target surface being inspected by the inspection device. The inspection device may be capable of measuring a reflectance of the target surface to determine various properties of the surface, such as its morphology, quality, roughness, and so on. The inspection device may further be capable of determining the precise location of the target surface, such as the distance from the surface to the inspection device. In one implementation, where the target surface is flat, determining precise location of the target surface may include determining a single distance from the target surface to some reference point (e.g., a plane of the inspection device). In other implementations, the target surface may have a complicated profile that includes a number of ridges, recesses, kinks, grooves, flat regions, rounded regions, and so on. In such implementations, determining precise location of the target surface may include determining a detailed entire profile of the target surface. For example, the profile of the target surface may be represented by a dependence of a height (width, depth) of the target surface, counted from some reference surface (e.g., a horizontal or a vertical plane), on the distance along this reference surface. The profile may be characterized by a discrete (or a quasi-continuous) set of locations with the resolution determined by a spacing between adjacent locations. The spacing may be pre-set based on the required resolution of the target surface imaging. The desired resolution may require setting a particular speed of the inspection device and/or sampling rate of an optical sensor system mounted on the inspection device. 
     The disclosed implementations pertain to a variety of manufacturing techniques that use processing chambers (that may include deposition chambers, etching chambers, and the like), such as chemical vapor deposition techniques (CVD), physical vapor deposition (PVD), plasma-enhanced CVD, plasma-enhanced PVD, sputter deposition, atomic layer CVD, combustion CVD, catalytic CVD, evaporation deposition, molecular-beam epitaxy techniques, and so on. Although the most significant practical impact of the disclosed implementations may be expected to occur in techniques that use vacuum deposition chambers (e.g, ultrahigh vacuum CVD or PVD, low-pressure CVD, etc.), the same systems and methods may be utilized in atmospheric pressure deposition chambers for non-intrusive monitoring of the chamber conditions that exist during deposition processes. 
       FIG. 1A  illustrates one exemplary implementation of a manufacturing machine  100  capable of supporting optical inspection of targets therein. In one implementation, the manufacturing machine  100  includes a loading station  102 , a transfer chamber  104 , and one or more processing chambers  106 . The processing chamber(s)  106  may be interfaced to the transfer chamber  104  via transfer ports (not shown). The number of processing chamber(s) associated with the transfer chamber  104  may vary (with three processing chambers indicated in  FIG. 1A  as a way of example). The transfer chamber  104  may include a robot  108 , a robot blade  110 , and an inspection device  112  for optical inspection of an exemplary target  116  located in one of the processing chambers  106 . The transfer chamber  104  may be held under pressure (temperature) that is higher (or lower) than the atmospheric pressure (temperature). 
     The robot  108  may transfer various devices (e.g., semiconductor wafers, substrates, liquid crystal displays, reticles, calibration devices) between the load station  102  and one of the processing chambers  106 . The robot  108  may require calibrations for a variety of reasons including preventive maintenance, restarting or recalibrating the manufacturing machine  100 , and/or replacing various components of the manufacturing machine  100 . 
     In one implementation, the robot  108  may include a robot blade  110  to support the inspection device  112  when the inspection device is transferred into one of the processing chambers  106 . The robot blade  110  may be attached to an extendable arm sufficient to move the robot blade  110  near the target  116  so that the inspection device  112  may explore one or more target surfaces of the target  116 . The target  116  may be a wafer, a substrate chuck, an edge ring, or any other object/tool located in one of the processing chambers  106  (or in the loading station  102 , the transfer chamber  104 , the ports connecting the transfer chamber  104  to the loading station  102  or the processing chambers  106 ). The inspection device  112  may have one or more optical sensors  114 . The inspection device  112  may include an alignment point in order to properly align the inspection device  112  relative to the robot blade  110 . The alignment point may be a hole, notch, or indent and may be centered in a pocket or depression of the robot blade  110 . The plurality of optical sensors  114  of the inspection device  112  may be capable of sensing visible light or other electromagnetic radiation coming from the target surface (e.g. reflected by that surface) of the target  116 . The light detected by the optical sensors  114  may be reflected from the target surface where the light may be directed by one or more light sources. In some implementations, the light sources may be mounted on the same inspection device  112  (e.g., be part of the sensors  114 ). In other implementations, the light sources may be located outside the inspection device, e.g., mounted inside the transfer chamber  104 , the loading station  102  or the processing chambers  106 . The robot blade  110  and the inspection device  112  may enter the processing(s) chamber  106  through a slit valve port (not shown) while a lid to the processing chamber(s)  106  remains closed. The processing chamber(s)  106  may contain processing gases, plasma, and various particles used in deposition processes. A magnetic field may exist inside the processing chamber(s)  106 . The inside of the processing chamber(s)  106  may be held at temperatures and pressures that are different from the temperature and pressure outside the processing chamber(s)  106 . The temperatures and pressures inside the processing chamber(s)  106  may be similar to those that correspond to the actual on-line processing conditions. 
     A computing device  118  may control operations of the robot  108  and the inspection device  112 . The computing device  118  may communicate with an electronics module  150  of the robot  108 . In some implementations, such communication may be performed wirelessly. 
       FIG. 1B  illustrates the electronics module  150  capable of facilitating wireless optical inspection of targets inside the manufacturing machine  100 , in one exemplary implementation. The electronics module  150  may include a microcontroller  152  and a memory buffer  154  coupled to the microcontroller  152 . The memory buffer  154  may be used to collect and store inspection data before transmitting the inspection data to the computing device  118 . In some implementations, the inspection data may be transmitted using a wireless communication circuit. In other implementations, the data may be transmitted using a wired connection between the electronics module  150  and the computing device  118 . In some implementations, the inspection data may first be stored (buffered) in the memory buffer  154  prior to being transmitted to the computing device  118 . In other implementations, the inspection data may be transmitted to the computing device  118  as the data is collected, without being stored in the memory buffer  154 . In some implementations, the wireless or wired connection may be continuous. In other implementations, the wireless or wired connection may be established periodically or upon completion of the inspection or some other triggering event (e.g., when the memory buffer  154  is close to being full). The electronics module  150  may further include a power element  156  and a power-up circuit  158 . In some implementations, the power element  156  may be a battery. In some implementations, the power element  156  may be a capacitor. The power element  156  may be rechargeable from a power station  180 . For example, the battery or the capacitor may be recharged upon a contact (e.g., via a charging docking station) with the power station  180  when the inspection device is withdrawn from the chamber. In some implementations, the charging station may be connected (e.g., via a wired connection) to the power element  156  even when the inspection device is inserted into the chamber. In some implementations, the connection between the charging station  180  and the power element  156  may be wireless. In some implementations, the charging station  180  may include a power transmitter and the power element  156  may include a power receiver. The wireless power transmission may be activated when the inspection device is withdrawn from the chamber, in some implementations. In other implementations, the wireless power transmission may be activated even when the inspection device is inside the chamber. When the power element  156  is low on power, the power element  156  may send a beacon signal to the find the power station  180  and the power station  180  may provide a power signal to the power element  156  until the power element is recharged to the required level. 
     The microcontroller  152  may be coupled to one or more optical sensors  114  (one exemplary optical sensor is depicted in  FIG. 1B ). The optical sensor  114  may include a light source  164  and a light detector  166 . The electronics module  150  may also include an accelerometer  168  to facilitate accurate extension and angular rotation of the robot blade  110 . The electronics module  150  may also include a temperature sensor  170  to detect temperature near the target  116 . 
     The electronics module  150  may further include a wireless communication circuit, i.e. a radio circuitry for receiving wireless instructions from the computing device  118  and for transmitting optical inspection data to the computing device  118 . For example, the radio circuitry may include an RF front end module  160  and an antenna  162  (e.g., a UHF antenna  162 ), which may be an internal ceramic antenna, in one implementation. The batteries may be of a high temperature-tolerant type such as lithium ion batteries that can be exposed to a chamber temperature of 450 degrees C. for a short time period such as one to eight minutes. 
     Some components shown in  FIG. 1B  may be located on or at the stationary part of the robot  108 . For example, the microcontroller  152 , the memory buffer  154 , and the RF front end  160  may be so located. Other components of the electronics module  150  may be located on or at the robot blade  110  of the robot  108  and or the inspection device  112  supported by the robot blade. For example, the optical sensors  114 , the accelerometer  168 , and the temperature sensor  170  may be so located. In some implementations, some of the components of the electronics module  150  may be located both at the stationary part of the robot  108  and the extendable robot blade  110 , e.g., power element  156  may be so located. In some implementations, two separate microcontrollers may be implemented, with one of the microcontrollers located on the stationary part of the robot  108  and the other microcontroller located on the inspection device  112 . 
     The wireless connection facilitated by the RF front end  160  and antenna  162  may support a communication link between the microcontroller  152  and the computing device  118 , in some implementations. In some implementations, the microcontroller  152  integrated with the robot  108  may have a minimal computational functionality sufficient to communicate information to the computing device  118 , where most of the processing of information may occur. In other implementations, the microcontroller  152  may carry out a significant portion of computations, while the computing device  118  may provide computational support for specific, processing-intensive tasks. Data received by the computing device  118  may be data obtained from the inside of the transfer chamber  104 , the processing chambers  106 , data generated by the inspection device  112 , data temporarily or permanently stored in the memory buffer  154 , and so on. The data stored in the memory buffer  154  and/or transmitted to or from the computing device  118  may be in a raw or processed format. 
     In one implementation, the inspection device  112  may determine (using the processing capabilities of the microcontroller  152  and/or the computing device  118 ) the instant positions of the optical sensors  114  and infer (from those positions) the locations on the target surface where the light detected by the optical sensors is coming from. Using the instant positions of the optical sensors  114 , the microcontroller  152  and/or the computing device  118  may map one or more profiles (e.g., a vertical profile, a horizontal profile) of the target surface. The locations of the optical sensors relative to the target  116  (or the target surface) may be controlled via precise parallel and rotational motion of the inspection device  112 . For example, as illustrated schematically in  FIG. 1A , the robot blade  110  may be capable of moving the inspection device  112  to a required distance into the processing chamber  106 . The robot blade  110  may further be capable of rotating the inspection device  112  to a required angle, in some implementations. As a result, one or more optical sensors  114  may be capable of hovering over (or under) any point of the surface of the target  116  and exploring one or more profiles of the target surface near that point. Upon collecting data about the target surface near a specific location, the robot blade  110  may reposition the optical sensors  114  in such a way that a different location of the target surface is in focus of the repositioned optical sensors  114 . For example, the robot blade may parallel-shift the inspection device  112  by an additional distance and/or rotate the inspection device  112  by an additional angle. The microcontroller  152  (or computing device  118 ) may determine the coordinates of the center of the inspection device  112  as well as the angle of rotation of the inspection device  112  relative to a reference position (e.g., zero position) of the target  116 . Alternatively, the computing device  118  may determine coordinates of the target  116  with respect to a reference position of the robot blade  110 . The computing device may determine an offset between the center of the target  116  and the alignment point or a center line of the robot blade  110  in a reference position. The microcontroller  152  and/or computing device  118  may calibrate the robot  108  based on the determined offset. The computing device  118  of the manufacturing machine  100  may include a blade control module  120 , an optical sensor control module  122 , and a surface profile analysis module  124 , in one implementation, as well as a central processing unit (CPU), software, and memory (as shown in  FIG. 8 ). In some implementations, some of the functionality of the blade control module  120 , the optical sensor control module  122 , and the surface profile analysis module  124  may be implemented as part of the electronics module  150  by the microcontroller  152  and the memory buffer  154 . 
       FIG. 2  illustrates an inspection device setup  200  for performing optical inspection of targets and target surfaces within electronic device manufacturing machines, in one exemplary implementation. The target  116  in the setup  200  may include an electrostatic chuck  202  (also commonly referred to as pedestals or heaters) or any other tool capable of holding a wafer during a manufacturing process. The target  116  in the setup  200  may also include the edge ring  204 , the wafer  206 , or any other object or component of the processing chamber  106 . The wafer  206  may be supported above the surface of the chuck  202  with lift pins  208 . For example, the wafer may be initially placed on the wafer-receiving surface (e.g., the upper surface of the chuck  202 ) and subsequently lifted above that surface. In some implementations, the wafer  206  may not be present when the inspection device  112  is to inspect the target surfaces. For example, the inspection device  112  may be shaped similarly to the standard wafer  206  and placed by the robot blade  110  in the standard location of the wafer  206 , e.g., on the wafer-receiving surface of the chuck  202 . Furthermore, the inspection device may be handled similarly to the wafer  206 , e.g., lifted above the wafer-receiving surface and/or the edge ring  204  by lift pins  208  to a height necessary or optimal for performing the optical inspection of the target surfaces. 
     The optical inspection may be performed using one or more optical sensors  114 . For example, as illustrated in  FIG. 2 , the optical sensor may be used to inspect the surface of the edge ring  204  (shown schematically as performed by the sensor  114 ( 1 )). The optical sensor may be used to inspect other target surfaces or areas, such as the surface/edge of the wafer  206  (shown schematically as performed by the sensor  114 ( 2 )), the surface of the chuck  202 , a gap between the chuck  202  and the edge ring  204 , a gap between the edge ring  204  and the wafer  206 , and so on. 
       FIG. 3A  illustrates an inspection device setup  300  for performing optical inspection of the surface of the edge ring  204 , in one exemplary implementation. After the inspection device  112  is delivered to the processing chamber  106  by the robot blade  110 , the surface of the edge ring  204  may inspected with the optical sensors  114 .  FIG. 3A  illustrates one exemplary geometry of the edge ring  204 . Specifically, in the setup  300 , the edge ring  204  surrounds the wafer-receiving surface  210 , which under the normal processing conditions is to receive the wafer  206 . In some implementations, the wafer  206  may not be present when the inspection device  112  is inserted into the processing chamber  106 . In such implementations, the robot blade  110  may be withdrawn after the inspection device  112  is delivered and placed on the wafer-receiving surface  210 . The inspection device  112  may then be lifted on the lift pins above the wafer-receiving surface  210  and the edge ring  204 . In other implementations, the inspection device  112  may be inserted while the wafer  206  is positioned on the wafer-receiving surface  210 . This may have an advantage of additionally allowing the inspection device  112  to determine the gap between the wafer  206  and the edge ring  204 . In such implementations, the robot blade  110  may remain inside the processing chamber  106  and provide support for the inspection device  112  while the inspection device hovers above the edge ring  204 . 
     The inspection device  112  may have optical sensors  114  that may include one or more light sources  164  and light detectors  166 . A light beam produced by the light source  164  may be a coherent beam, such as a laser beam, in some implementations. In other implementations, the light source  164  may produce natural light, linearly, circularly, or elliptically polarized light, partially-polarized light, focused light, and so on. The light source  164  may produce a continuous beam of light or a plurality of discrete pulsed signals. The light source  164  may produce a collimated beam of light, a focused beam of light, or an expanded beam of light. The light source  164  may produce a monochromatic beam having a frequency/wavelength within a narrow region of frequencies/wavelengths near some central frequency/wavelength, in some implementations. Alternatively, multiple monochromatic light beams may be used. In other implementations, the light source  164  may produce a beam with a broad spectral distribution, e.g., a white light. In some implementations, the beam may be in the visible part of the spectrum. In some implementations, the spectral distribution of the beam may include infrared or ultraviolet frequencies undetectable to a human eye. 
     In one implementation, the light source  164  may include a light-emitting diode (LED) which may produce a wide (uncollimated) incoherent beam having a range of wavelengths. The light (visible or infrared) produced by LED may, in some implementations, be collimated or focused by one or more lens of the light source  164  (not shown in  FIG. 3A ) to increase the intensity of the light incident on the inspected surface (and, therefore, increase the intensity of the light reflected from the surface), for the ease of detection. 
     In another implementation, the light source  164  may include a laser (e.g., a low-power laser diode), which may produce a narrow beam, e.g., a well-collimated beam, which may also have a narrow spectral width (compared with the light from a typical LED). A well-collimated beam with a narrow spectral width may provide a number of advantages. For example, a well-collimated beam may be capable of accessing narrow areas of the target surface (such as deep and narrow crevasses) that may be missed by a wide beam. Additionally, a spectrally-narrow beam may allow the use of narrow band optical filters to filter out spurious light (e.g., ambient light) that may enter the processing chamber  106 , for example through one or more view ports in the chamber walls. Such an optical filter may be used as part of the light detector  166  (not shown explicitly on  FIG. 3A ), which may additionally have one or more focusing lenses. 
     The optical sensors  114  (that may include both the light source and the light detector  166 ) may be positioned at some working distance above the inspected target surface (such as the surface of the edge ring  204 ). The working distance may be determined by the focal distances of the lens used in optical sensors  114 . For example, in some implementations, the working distance may be within 9-15 mm, although in other implementations shorter or longer working distances (e.g., distances in excess of 35 mm) may be used. 
     In some implementations, the optical sensor  114  may operate in a discrete sampling mode, with a sampling frequency that may be adjusted based on the speed of the inspection device (set by the speed of insertion or retraction of the robot blade  110 ). For example, if the sampling frequency is 500 Hz whereas the speed of the inspection device is 25 mm/sec, the spatial resolution of the optical inspection may be 25 mm/sec=500 Hz=50 um. In other words, the inspection device  112  may be capable of measuring reflectance of the target surface once every 50 microns. In other implementations, the resolution of the target surface profile may be improved further by either decreasing the speed of the inspection device or increasing the sampling rate, or both. For example, if the sampling frequency is increased to 1 kHz whereas the speed of the inspection device is reduced to 5 mm/sec, the spatial resolution of the optical inspection will be 5 mm/sec÷ 1000 Hz=5 um. In other words, the inspection device  112  may be capable of measuring reflectance of the target surface once every 5 microns. 
     In some implementations, the speed of the inspection device and/or the sampling rate may vary depending on the specific target or target surface that is being inspected. For example, the speed of the inspection device may be lower (and/or the sampling rate may be higher) where a higher resolution is required, e.g. when the edge ring  204  is being inspected. In contrast, the speed may be increased (and/or the sampling rate may be reduced) for faster inspection, where a lower resolution may be sufficient, e.g., when the inspection device  112  passed over the wafer receiving surface. 
     The target surface inspection may be performed when the inspection device  112  is being inserted (i.e. on the forward motion) or when the inspection device  112  is being withdrawn (i.e. on the backward motion) or on both occasions, if a more thorough inspection is required. 
       FIG. 3B  illustrates an inspection device setup  350  for clearance measurements in processing chambers, in one exemplary implementation. The inspection device setup  300  of  FIG. 3B  may also be used for calibration purposes. For example, in some implementations, the distance-measuring capability of the inspection device  112  may be used to characterize the inspection device itself and/or the robot  108  and its components, such as the robot blade  110 . More specifically, the optical sensor(s)  114  may be used to determine the vertical distance (clearance) between the inspection device  112  and some reference plane. The reference plane may be a flat part of the edge ring  204  (as shown in  FIG. 3B ), the surface of the chuck  202 , or some other stable reference plane whose location is likely to remain constant during use of the manufacturing machine  100 . In contrast, the extendable robot blade  110  may be subject to drooping—deflection of the robot blade  110  in the vertical direction, away from an ideal horizontal plane. The amount of drooping may be different for different extensions of the blade. For example, blade drooping may be the most significant for maximum extensions of the blade. To determine the amount of drooping, the optical inspection device  112  may perform vertical distance measurements in the same or a similar manner as described above in reference to  FIG. 3A  and the edge ring profilometry, e.g., by using optical triangulation techniques. 
     The working distance—the vertical distance between the inspection device  112  (or its optical sensor(s)  114 ) and the target surface—may be up to 100 mm or even longer, in some implementations. The accuracy of determining vertical distances for calibration purposes (e.g., drooping) may be at least 25 micron, or less, in some implementations. By performing a series of vertical distance measurements for a plurality of extensions (in the horizontal direction) of the robot blade  110 , the inspection device  112  may determine a dependence of the amount of drooping (e.g., of the distal end of the inspection device) on the robot blade extension. The data for the amount of drooping may subsequently be used for a variety of purposes. For example, the robot  108  and/or the robot blade  110  may be manually or automatically adjusted to remove/reduce drooping, in one implementation. In another implementation, the drooping data may be used to compensate for the drooping error, for example by adjusting the vertical positioning of the robot blade  110 . Such adjusting may be performed when the robot  108  is first set up. In some implementations, a new readjustment (followed by taking a new drooping data) may be performed after mechanical modifications of the robot components and/or stations/chambers tools. In some implementations, a readjustment may be performed at regular time intervals. 
       FIG. 4  illustrates inspection data obtained using the inspection device setup  300  for performing optical inspection of the surface of the edge ring  204 , in one exemplary implementation. The data shown in  FIG. 4  relates to two exemplary edge rings—a new ring and a worn ring. The data shown in  FIG. 4  is intended to demonstrate a concept of optical inspection in an illustrative and non-limited way. The data shown in  FIG. 4  may be collected and processed by the computing device  118  and one or more of its modules. For example, the blade control module  120  may set the inspection device speed. The set speed may be a fixed speed, in one implementation. In another implementation, the speed may be set based on instructions from the surface profile analysis module  124 . For example, depending on the type of the target surface inspected, the surface profile analysis module  124  may instruct the blade control module  120  to increase or decrease the speed of the inspection device  112 . 
     Using the known value of set speed, the blade control module  120  may map the time that has elapsed since some reference time—e.g., the time of the initial alignment of the inspection device  112  (or one of its optical sensors  114 ) with some reference point on the target surface. For example, the bottom panel of  FIG. 4  may establish the position-to-time correspondence in an exemplary situation of the robot blade (end effector) moving the inspection device with the speed of 5 mm/sec. 
     The optical sensor control module  122  may set (alone or in conjunction with the surface profile analysis module  124 ) the sampling rate of the optical sensing. The upper panel of  FIG. 4  illustrates a reflected light intensity (normalized by some arbitrary scale) of the light emitted by the light source  164  and detected by the light detector  166 . The left plateau extending from 0 to approximately 3 sec corresponds to wafer-receiving surface  210  of the chuck  202 . The wafer-receiving surface  210  in the illustrative example of  FIG. 4  is smooth but relatively dull, which results in a constant but relatively low reflectivity. Between approximately 3 sec and 4.5 sec, the optical sensor  114  of the inspection device  112  measures reflectivity of the gap between the wafer-receiving surface  210  and the edge ring  204  whereas from 4.5 sec the optical sensor  114  beings exploring the profile of the edge ring  214 . Depending on the state of the edge ring, the reflectance may vary significantly. For example, a new ring&#39;s reflectance (depicted in  FIG. 4  with the solid line) may be uniform and high for a significant portion of the edge ring (from approximately 5.5 sec to 9.5 sec). In contrast, a used and worn-out ring may display a reflectance (depicted with the dashed line) that is significantly smaller and less uniform. Such non-uniformity and diminishing of the reflectance may indicate that the surface morphology of the edge ring  204  has deteriorated to an extent where performance of the edge ring  204  has become inadequate. 
     The relative decrease in the reflectance may be calibrated for various materials used for the edge rings, and the calibrated reflectance may be used to indicate when the edge ring is to be replaced. Such indications may be specific for a given type of material used in the edge rings. For example, an edge ring made of a polished quartz or a polished SiC may be characterized with a high reflectivity when the edge ring is new and a quick decrease in the reflectivity once the edge ring begins to wear out. On the other hand, an edge ring made of a bead-blasted material (quartz or SiC) may be characterized by a relatively low reflectivity when the edge ring is new but a slower decrease in the reflectivity with the time of use. 
     In addition to measuring reflectance of the target, the inspection device  112  may perform profilometry of the target surface. The profilometry technique allows extracting topographical data characterizing the target surface. For example, the optical sensors  114  may also measure (in addition to measuring the reflectance, as explained above) the local distance from the target surface to some reference point (or a reference plane) of the inspection device  112 . This may allow to determine a one-dimensional profile h(x) of the target surface, where h is the height of the target surface, in one implementation, and x is the distance along some known line. For example, x may be the distance along a path of the optical sensor  114  relative to the target surface. In some implementations, the profile may be two dimensional, h(x,y), with x and y being two coordinates (e.g., Cartesian or polar coordinates) within a plane of the target surface. The height of the surface h may be measured using optical triangulation or interferometry techniques. 
     In the optical triangulation method, a microcontroller  152  (and/or a computing device  118 ) may infer a point where the line corresponding to a narrow incident beam (produced, e.g, by a laser diode light source  164 ) and the line corresponding to a reflected beam (e.g., detected by a light detector  166 ) intersect. The direction of the incident beam may be calibrated into the optical triangulation method and the direction of the reflected beam may be determined from the maximum reflected beam intensity, as detected by a distribution of the reflected beam intensity, e.g., captured by a CCD (charge-coupled device) detector, in one implementation. 
     In the interferometry method, a beam of light produced by the light source  164  may be processed by a miniature (inch-size) microinterferometer incorporated in the optical sensor  114 . The microinterferometer may include a beam splitter, which may split the beam into at least two parts. A first part of the split beam may be reflected off the target surface before being mixed with the second part of the beam (which travels along a fixed reference path) in order to produce an interference picture. The microinterferometer may be mounted on the inspection device  112 . Depending on the character of interference (maxima or minima) of the two parts of the beam, the distance from the light detector  166  to the target surface may be determined, and hence may be determined the local value of h. 
     Based on the triangulation technique or an interferometry method, the inspectin device may determine a morphology of the target surface and to map out various shapes of the target surface—slopes, peaks, valleys, ridges, and other features of the target surface. 
     The surface profile analysis module  124  may pass the reflectivity and/or profilometry data obtained by the optical sensor(s)  114  to a human operator, in one implementation. The human operator may assess the quality of the surface of the target (e.g., of the edge ring  204 ) and determine that the target needs to be replaced (or not). In other implementations, the surface profile analysis module  124  may perform the assessment without an input of the human operator. For example, the surface profile analysis module  124  may retrieve (from memory) a calibration data for the target surface and determine from a comparison of the calibration data with the reflectivity or profilometry data whether the target component needs to be replaced. For example, in some implementations, the surface profile analysis module  124  may compare a minimum reflectance or a minimum height of the target surface profile measured anywhere on the target surface with the corresponding calibration thresholds. In case the minima are below the thresholds (meaning that at least in some locations on the target surface its performance is sub-optimal), the surface profile analysis module  124  may output a recommendation to replace the target. In other implementations, the surface profile analysis module  124  may output a replacement recommendation if a pre-set fraction of the target surface has a sub-threshold reflectance and/or profile. In yet other implementations, the surface profile analysis module  124  may output a replacement recommendation if an average reflectance and/or profile of the target surface are below the corresponding calibration thresholds. 
       FIG. 5  illustrates an inspection device setup  500  for performing horizontal optical inspection of the surface of the edge ring  204 , in one exemplary implementation. Whereas the inspection device setup  300  facilitates vertical optical inspection of the surface of the edge ring (or a chuck  202 )—where the emitted and reflected light signals propagate along the vertical (or close to vertical) direction—the inspection device setup  500  facilitates horizontal scanning of the target surface. In one exemplary implementation, the robot blade  110  may deliver the inspection device  112  to the wafer-receiving surface  210 . The robot blade  110  may subsequently withdraw from the processing chamber  106 . The inspection device  112  may then be lifted using lift pins  208  to a height y determined by instructions from the blade control module  120  or the optical sensor control module  122 . The optical sensor  114  mounted on the edge of the inspection device may emit light from the light source (not shown). The emitted light may reflect off the target surface (here, the surface of the edge ring  204 ) and propagate back to the light detector (not shown). The measurements may be repeated for a plurality of elevations y of the inspection device  112 , and a dependence of the reflectivity on the elevation y may be determined. Similarly, the horizontal profile of the target surface w(y) may be determined. Subsequently, the surface profile analysis module  124  may provide the determined information to a human operator and/or assess if the target (e.g., the edge ring  204 ) may need to be replaced, as explained above in relation to vertical scanning. 
       FIG. 6A  illustrates an inspection device setup  600  for performing optical inspection of a gap  610  between the chuck  202  and the edge ring  204  (“chuck-to-edge ring gap”), in one exemplary implementation. When a new edge ring  204  is installed (e.g., in place of a worn-out edge ring), it may be important to ensure that the new edge ring  204  is properly centered around the chuck  202 . More specifically, a properly set edge ring  204  has a chuck-to-edge ring gap  610  that is uniform (within the tolerances of the processing chamber specifications) around the circumference of the edge ring  204 . The inspection device  112  may be positioned (by the robot  108 ) so that the optical sensor  114  is to inspect the chuck-to-edge ring gap  610  and to determine the size of this gap at a specific location of the edge ring  204  (and/or the chuck  202 ). The robot blade  110  may then rotate the inspection device so that the optical sensor  114  is to inspect the chuck-to-edge ring gap  610  at a different location of the edge ring  204 . As a result, the computing device  118  may receive, from the inspection device  112 , a plurality of data describing the accuracy of the edge ring centering around the chuck  202 . 
     In some implementations, the entire plurality of data may be received by the same optical sensor  114 , which is driven by the robot blade  110  to make a full circle around the circumference of the chuck  202 /edge ring  204 . In some implementations, multiple (e.g., N) optical sensors  114  may be involved in obtaining the chuck-to-edge ring gap data, so that each of the optical sensors may only have to be rotated by a fraction of the full circle (e.g. to 360/N degrees). 
     If the chuck-to-edge ring gap  610  is within acceptable tolerances of the specification, the computing device  118  may output an indication that the edge ring  204  is aligned properly. If, on the other hand, the chuck-to-edge ring gap  610  varies outside the acceptable tolerances, the computing device  118  may output a warning indication (e.g., to a human operator) that the edge ring  204  may need to be repositioned/recalibrated. The computing device  118  may also schedule a downtime to replace or readjust the edge ring  204 . In some implementations, the computing device may perform readjustment without involving a human operator. For example, during the scheduled downtime (or, in some implementations, immediately after the optical inspection revealed a misalignment), the robot  108  may insert a calibration device and readjust the edge ring  204 . In some implementations, inserting the calibration device may require withdrawing the optical inspection device  112 . In other implementations, the calibration device may be inserted while the inspection device  112  remains inside the processing chamber  106 . In such instances, the inspection device  112  may be capable of quickly re-inspecting the repositioned edge ring  204  and confirm if the realignment operation has been successful. In some implementations, the calibration device and the inspection device  112  may be a single device that in addition to the inspection functionality may have a capability of moving objects inside the processing chamber  106 . 
     The computing device  118  may schedule edge ring alignment check-ups at specific (e.g., regular) time intervals to ensure that the edge ring  204  has not drifted away from its aligned location during manufacturing. 
       FIG. 6B  illustrates an inspection device setup  650  for performing optical inspection of a gap  660  between the wafer  206  and the edge ring  204  (“wafer-to-edge ring gap” or “pocket gap”), in one exemplary implementation. When a wafer  206  is introduced into the processing chamber  106  and placed on the wafer-receiving surface  210 , it may be important to ensure that the wafer is properly centered on the chuck  202  inside the wafer pocket. More specifically, a properly placed wafer  206  has a wafer-to-edge ring gap  660  that is uniform (within the tolerances of the processing chamber specifications) around the circumference of the edge ring  204 . The inspection device  112  may be positioned (by the robot  108 ) so that the optical sensor  114  is to inspect the wafer-to-edge ring gap  610  and to determine the size of this gap at a specific location of the edge ring  204  (and/or the chuck  202 ). The robot blade  110  may then rotate the inspection device so that the optical sensor  114  is to inspect the wafer-to-edge ring gap  660  at a different location of the edge ring  204 . As a result, the computing device  118  may receive, from the inspection device  112 , a plurality of data describing the accuracy of the wafer positioning on the chuck  202 . 
     As in the case of detecting the chuck-to-edge ring gap  610 , determining the wafer-to-edge ring gap  660  may be performed with one or multiple optical sensors  114 . If misalignment of the wafer  206  is detected outside the tolerances of the processing chamber specification, the computing device  118  may readjust the positioning of the wafer  206 . In some implementations, this may be achieved in the way similar to the above-described readjustment of the edge ring  204 . 
       FIG. 7  is a flow diagram of one possible implementation of a method  700  of optical inspection of manufacturing device chambers and components. Method  700  may be performed using systems and components shown in  FIGS. 1A-B ,  2 ,  3 A-B,  5 ,  6 A-B or some combination thereof. Method  700  may be performed using a single optical sensor or a plurality of light sensors. The light sensors may be configured for vertical scanning, as illustrated, e.g., in  FIGS. 2, 3A -B, or for horizontal scanning, as illustrated in  FIG. 5 , or some oblique scanning using similar setups to those described above. Some or all blocks of the method  700  may be performed responsive to instructions from the computing device  118  or the microcontroller  152 , in some implementations. The computing device  118  may have one or more processing devices (e.g. central processing units) coupled to one or more memory devices. The method  700  may be performed without taking a manufacturing system (such as the manufacturing machine  100 ) off the production process. In some implementations, the optical inspection method may be performed while a wafer is present inside a processing chamber. In some implementations, the method  700  may be implemented with no wafer in the processing chamber, for example after the last wafer has been processed and removed from the processing chamber but before the next wafer is loaded into the processing chamber. The optical inspection method may be performed under conditions (e.g., at pressures and temperatures) that are similar to the actual conditions of the processing chamber during the manufacturing process. Accordingly, the manufacturing process may occur at low temperatures, or at temperatures that are less or significantly less than the room temperature. Alternatively, the manufacturing process may occur at the room temperature, above the room temperature, or significantly above it. In some implementations, the pressure inside the chamber may be less or significantly less than the atmospheric pressure, including low vacuum or high vacuum conditions. 
     The method  700  may include transferring, by a robot blade  110 , an inspection device  112  into a processing chamber  106 , the inspection device  112  having at least one optical sensor ( 710 ). In some implementations, the inspection device  112  may have dimensions (and a shape) that are similar to the dimensions of a wafer. Correspondingly, handling of the inspection device  112  by the robot  108  may be performed in a way that is similar to the manner in which the robot  108  handles a wafer. For example, the robot  108  may extend the robot blade  110  from the transfer chamber  104  into the loading station  102  (through a transfer port) and receive the inspection device  112  from the loading station. The robot blade  110  may subsequently withdraw back into the transfer chamber  104 . The robot  108  may then rotate the robot blade  110  towards one of the processing chambers  106  and extend the robot blade  110  with the attached to it inspection device  112  into the processing chamber  106  (through another transfer port or valve). 
     The microcontroller of the robot  108  may control the motion of the robot blade so that one or more of the plurality of optical sensors  114  of the inspection device  112  is brought near a target surface located within the processing chamber  106 . 
     The method  700  may continue with detecting, by one or more optical sensors, a light reflected from the target surface ( 720 ). The light reflected from the target surface may be directed at the target surface by one or more light sources that may be mounted on the inspection device  112 . The light source(s) may direct a constant beam of light at the target surface, in one implementation. In another implementation, the beam directed by the light source(s) may be pulsed, with the frequency of pulsing (sampling rate) controlled by the microcontroller  152  of the robot  108 . In some implementations, a microcontroller of the inspection device that is separate from the microcontroller  152  may control the sampling rate. In some implementations, the robot blade  110  may be moving while the inspection device  112  obtains light reflection data from the target surface. The speed of the robot blade  110  (and the inspection device  112  supported by the robot blade) may be tuned to a pre-determined resolution that may be adequate for a particular region of the target surface that is being inspected. For example, the speed may be lower for regions of the target surface that require a higher resolution, such as the regions of the edge ring that are proximate to the wafer edge, in one implementation. Conversely, the speed may be increased for regions that require a lower resolution, such as the regions of the edge ring that are farther away from the wafer. 
     The optical sensor may generate a signal that is representative of a state of the region of the target surface and output the signal to a processing device ( 730 ). The signal generated by the optical sensor may be analog or digital. In some implementations, the signal may carry information about the intensity of the light reflected from the target surface. For example, the signal may carry information about the ratio of the reflected light intensity to the incident light intensity (i.e., information about reflectivity of the surface). Such a signal may be representative of the state (e.g., condition) of the target surface. For example, a higher intensity of the reflected light may indicate a smooth surface that remains in a good working condition. On the other hand, a diminished reflectivity may indicate a rough surface whose functionality has deteriorated. 
     In another implementation, the state of the target surface may be a profile of the target surface determined via a plurality of measurements. A profile may be vertical, horizontal, or oblique. A vertical profile may represent the dependence of the height of the target surface on a horizontal coordinate (which may be discretized, per pre-determined resolution). For example, if y is the height of the target surface and x is a horizontal coordinate, the vertical profile of the target surface may be represented via a plurality of height measurements that determine the dependence of y on x: y(x). A horizontal profile may represent the dependence of the width (or thickness) of the target surface on a horizontal coordinate (which may also be discretized). A horizontal profile may represent a plurality of measurements of lateral dimensions of the target surface. For example, if x is the lateral position of the target surface and y is a vertical coordinate, the horizontal profile of the target surface may be represented via a plurality of lateral measurements that determine the dependence of x on y: x(y). An oblique profile may represent a similar dependence of some thickness of the surface on some arbitrary coordinate. Determining an oblique profile may be performed in instances where a surface of the target is tilted at some angle relative to the vertical or horizontal directions. 
     In some implementations, the target surface may include a plurality of regions of the chuck and a plurality of adjacent to them regions of the edge ring. The optical sensor may generate a signal that is representative of a plurality of gaps between each one of the plurality of regions of the edge ring and the adjacent one of the plurality of regions of the chuck. For example, the signal may contain information about the chuck-to-edge ring gaps at N locations around the circumference of the chuck. The computing device, which is to receive the signal, may determine, based on the chuck-to-edge ring gaps at N locations, a position of the edge ring relative to the chuck. For example, a geometric center of the edge ring may not be at the same point as a center of the chuck (in a situation where the chuck is circular). By comparing the sizes of the gaps at multiple locations, the computing device may determine the distance between the two centers (a radial offset between the chuck and the edge ring). 
     In some implementations, the chuck or the edge ring may not be perfectly circular, due to wear or by design. For example, the chuck or the edge ring may have a notch, a flat region, or any other structural feature that makes it important (or advantageous) to achieve a precise angular orientation of the edge ring to the chuck. For example, the chuck may have a recessed region and the edge ring may have a corresponding local alteration of the profile of its surface. The local alteration, for a proper operation of the edge ring, may have to be aligned with the recessed region. During installation of the edge ring (or from normal operations of the chamber), the alignment (orientation) of the edge ring (or the chuck) may be set incorrectly. By comparing the sizes of the gaps at multiple locations, the computing device may determine the angular offset in the relative orientation between the chuck and the edge ring. 
     In some implementations, the signal output by the optical sensor(s) may be a combination of the intensity signal and the profile signal. The same light detector, such as a CCD detector, may generate both signals. For example, the location of the brightest spot in the CCD array may indicate (in conjunction with the triangulation techniques) the angle of the reflected light beam (and hence the exact coordinates of the target surface) whereas the brightness of this spot may indicate the reflectivity of the target surface. 
     The signal generated by the optical sensor may be output to a processing device. The processing device may me the microcontroller of the inspection device  112 , the microcontroller  152  of the robot  108 , the CPU of the computing device  118 , or any combination thereof. For example, the microcontroller of the inspection device and/or the microcontroller of the robot may perform initial pre-processing of the output signal, while the computing device  118  may further process the signal, e.g., by converting the pre-processed signal into a user-accessible format. In some implementations, where the signal output by the optical sensor is in analog format, the output signal may first be input on an analog-to-digital converter (ADC), which may convert the output signal into a digital format before providing the converted signal to the processing device. 
     In some implementations, the output signal may be processed by the processing device immediately upon generation. In some implementations, a human operator may receive the processed signal in real time and may be able to instruct the robot  108  and the inspection device  112  to collect additional data, e.g., a data about a different region of the same target surface, a higher-resolution data for the same region of the target surface, or a data about a different target surface. In other implementations, the output signal may not be processed immediately. Instead, the data carried by the output signal may first be stored in the memory buffer  154  and spooled to the processing device at some later time, wirelessly or using a wired connection. In some implementations, the data may be spooled to the processing device periodically, at pre-determined time intervals. In some implementations, the data may be spooled upon an occurrence of a triggering event. For example, the data may be spooled when the buffer  154  is full (or 80% full, etc.) or upon completion of the inspection (e.g., when the inspection device  112  is removed from the chamber being inspected) or some portion of the inspection (e.g., upon inspection of some particular region of the target). In some implementations, the spooling of data may happen when the inspection device is removed from the chamber for charging. For example, a docking station (e.g., a USB docking station) that connects the inspection tool to the charging station  180  may also serve as a data transferring station so that the data transfer may occur before, after, or concurrently with charging of the power element  156 . 
     The method  700  may optionally continue with determining, from the state of the region of the inspected surface, that the target is in an inadequate condition, and, responsive to such determination, performing a maintenance operation on the target ( 740 ). The condition of the surface may be assessed based on a comparison of the processed signal with pre-stored calibration data. Such a comparison may indicate that the profile of the target surface has receded beyond an optimal value or the reflectivity of the target surface has fallen below a certain threshold. If a determination that the state of the target is sub-optimal is made, the processing device may schedule a maintenance operation. The maintenance operation may include replacement of the target, recalibration of the target, readjustment of the target, or some other maintenance operation. The scheduling of the maintenance operation may be performed by the processing device without an input of a human operator, in one implementation. In some instances, the scheduled maintenance operation may be performed by the robot  108  without involvement of the human operator. In other instances, the human operator may perform the maintenance operation. 
     In some implementations, the maintenance operation may be scheduled even when the condition of the target surface is adequate. For example, the data output by the optical sensor(s) may indicate that the target is in a misaligned state even though the physical conditions of the target surface do not require replacing the target. In such instances, the maintenance operation may still be scheduled to correct the alignment of the target. 
     The systems and methods disclosed herein may be used not only for quality monitoring during manufacturing, but may also be utilized for testing and development of various deposition chamber designs. The advantages of the disclosed implementations include, but are not limited to, the ability to inspect various tools and components of the manufacturing system, reduce system downtime, receive quick feedback during run-time in-chamber processing, an ability to implement chamber modifications during processing, measure the resulting changes to the chamber components, eliminate premature replacement of various tools and components, and so on. 
       FIG. 8  depicts a block diagram of an example processing device  800  operating in accordance with one or more aspects of the present disclosure. The processing device  800  may be the computing device  118  of  FIG. 1A  or a microcontroller  152  of  FIG. 1B , in one implementation. 
     Example processing device  800  may be connected to other processing devices in a LAN, an intranet, an extranet, and/or the Internet. The processing device  800  may be a personal computer (PC), a set-top box (STB), a server, a network router, switch or bridge, or any device capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that device. Further, while only a single example processing device is illustrated, the term “processing device” shall also be taken to include any collection of processing devices (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methods discussed herein. 
     Example processing device  800  may include a processor  802  (e.g., a CPU), a main memory  804  (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), etc.), a static memory  806  (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory (e.g., a data storage device  818 ), which may communicate with each other via a bus  830 . 
     Processor  802  represents one or more general-purpose processing devices such as a microprocessor, central processing unit, or the like. More particularly, processor  802  may be a complex instruction set computing (CISC) microprocessor, reduced instruction set computing (RISC) microprocessor, very long instruction word (VLIW) microprocessor, processor implementing other instruction sets, or processors implementing a combination of instruction sets. Processor  802  may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), network processor, or the like. In accordance with one or more aspects of the present disclosure, processor  802  may be configured to execute instructions implementing method  700  of optical inspection of manufacturing device chambers and components. 
     Example processing device  800  may further comprise a network interface device  808 , which may be communicatively coupled to a network  820 . Example processing device  800  may further comprise a video display  810  (e.g., a liquid crystal display (LCD), a touch screen, or a cathode ray tube (CRT)), an alphanumeric input device  812  (e.g., a keyboard), an input control device  814  (e.g., a cursor control device, a touch-screen control device, a mouse), and a signal generation device  816  (e.g., an acoustic speaker). 
     Data storage device  818  may include a computer-readable storage medium (or, more specifically, a non-transitory computer-readable storage medium)  828  on which is stored one or more sets of executable instructions  822 . In accordance with one or more aspects of the present disclosure, executable instructions  822  may comprise executable instructions implementing method  700  of optical inspection of manufacturing device chambers and components. 
     Executable instructions  822  may also reside, completely or at least partially, within main memory  804  and/or within processing device  802  during execution thereof by example processing device  800 , main memory  804  and processor  802  also constituting computer-readable storage media. Executable instructions  822  may further be transmitted or received over a network via network interface device  808 . 
     While the computer-readable storage medium  828  is shown in  FIG. 8  as a single medium, the term “computer-readable storage medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of operating instructions. The term “computer-readable storage medium” shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine that cause the machine to perform any one or more of the methods described herein. The term “computer-readable storage medium” shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media. 
     It should be understood that the above description is intended to be illustrative, and not restrictive. Many other implementation examples will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure describes 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 sense rather than a restrictive sense. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     The implementations of methods, hardware, software, firmware or code set forth above may be implemented via instructions or code stored on a machine-accessible, machine readable, computer accessible, or computer readable medium which are executable by a processing element. “Memory” includes any mechanism that provides (i.e., stores and/or transmits) information in a form readable by a machine, such as a computer or electronic system. For example, “memory” includes random-access memory (RAM), such as static RAM (SRAM) or dynamic RAM (DRAM); ROM; magnetic or optical storage medium; flash memory devices; electrical storage devices; optical storage devices; acoustical 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). 
     Reference throughout this specification to “one implementation” or “an implementation” means that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one implementation of the disclosure. Thus, the appearances of the phrases “in one implementation” or “in an implementation” in various places throughout this specification are not necessarily all referring to the same implementation. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more implementations. 
     In the foregoing specification, a detailed description has been given with reference to specific exemplary implementations. It will, however, be evident 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. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense. Furthermore, the foregoing use of implementation, implementation, and/or other exemplarily language does not necessarily refer to the same implementation or the same example, but may refer to different and distinct implementations, as well as potentially the same implementation. 
     The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example’ or “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” or “an implementation” or “one implementation” throughout is not intended to mean the same implementation or implementation unless described as such. Also, the terms “first,” “second,” “third,” “fourth,” etc. as used herein are meant as labels to distinguish among different elements and may not necessarily have an ordinal meaning according to their numerical designation.