Systems and methods for phase-shift interferometry utilizing in-SITU cavity calibration and laser non-linearity measurement

Abstract

A computer device includes at least one processor in communication with at least one memory device. The at least one processor is programmed to: a) receive, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) perform intensity scans of each pixel in the second plurality of pixels; c) identify zero transitions for each of the second plurality of pixels; and d) statistically evaluate the identified zero transitions by polynomial regression analysis.

Description

28744-6503 (231017.3) SYSTEMS AND METHODS FOR PHASE-SHIFT INTERFEROMETRY UTILIZING IN-SITU CAVITY CALIBRATION AND LASER NON-LINEARITY MEASUREMENT CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 669,979, filed July 11, 2024, which application is hereby incorporated by reference in their entireties. FIELD

[0002] The field of the disclosure relates to interferometry images of semiconductor wafers and, more particularly, to systems and methods for interferometer cavity calibration and LASER linearization in phase shift interferometry used for semiconductor wafer inspection and analysis. BACKGROUND

[0003] Phase-shift interferometry (PSI) for semiconductor wafer inspection and analysis relies strongly on correctly calibrated interferometer cavity and laser linearization. A mis-calibration will result in degraded measurement quality, visible as so-called “fringe-print-though” patterns. Typically, interferometer cavity and laser linearization are calibrated in regular maintenance intervals. In between maintenance intervals, this calibration is assumed to be constant. However, cavity calibration is subject to temperature variations and mechanical drift over time and laser linearization is subject to optical, electronic and mechanical drift of the laser. Therefore, individual measurements are subject to such calibration variations, resulting in varying measurement quality.

[0004] Known PSI techniques rely on high temperature stability and on calibrating the phase shift system (i.e., laser) in regular maintenance intervals and attempts to achieve a perfectly linear phase shift sequence during measurements. Other28744-6503 (231017.3) attempts to address cavity calibration and laser linearization issues include shortening maintenance intervals. Known methods attempt to calibrate the system control with the goal to achieve a perfectly linear phase shift sequence during measurements. Accordingly, a system to improve the calibration of the phase shift system is needed.

[0005] This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. BRIEF DESCRIPTION

[0006] In one aspect, a system includes a computing device that may include at least one processor in communication with at least one memory device. The at least one processor may be configured to: a) receive, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) perform intensity scans of each pixel in the second plurality of pixels; c) identify zero transitions for each of the second plurality of pixels; and d) statistically evaluate the identified zero transitions by polynomial regression analysis. The system may have additional, less, or alternate functionalities, including those discussed elsewhere herein.

[0007] In another aspect, a computer-implemented method may be performed by a computer device including at least one processor in communication with at least one memory device. The method may include a) receiving, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) performing intensity scans of each pixel in the second plurality of pixels; c) identifying zero transitions for each of the second plurality of pixels; and d) statistically evaluating the identified zero28744-6503 (231017.3) transitions by polynomial regression analysis. The method may have additional, less, or alternate functionalities, including those discussed elsewhere herein.

[0008] In a further aspect, a computer device includes at least one processor in communication with at least one memory device. The at least one processor may be configured to: a) receive, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) perform intensity scans of each pixel in the second plurality of pixels; c) identify zero transitions for each of the second plurality of pixels; and d) statistically evaluate the identified zero transitions by polynomial regression analysis. The computer device may have additional, less, or alternate functionalities, including those discussed elsewhere herein.

[0009] In another aspect, at least one non-transitory computer- readable media having computer-executable instructions embodied thereon, when executed by a computing device including at least one processor in communication with at least one memory device, the computer-executable instructions may cause the at least one processor to: a) receive, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) perform intensity scans of each pixel in the second plurality of pixels; c) identify zero transitions for each of the second plurality of pixels; and d) statistically evaluate the identified zero transitions by polynomial regression analysis. The non-transitory computer-readable media may have additional, less, or alternate functionalities, including those discussed elsewhere herein.

[0010] Advantages will become more apparent to those skilled in the art from the following description of the preferred embodiments which have been shown and described by way of illustration. As will be realized, the present embodiments may be capable of other and different embodiments, and their details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.28744-6503 (231017.3) BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The Figures described below depict various aspects of the systems and methods disclosed. Each Figure depicts an embodiment of a particular aspect of the disclosed systems and methods, and that each of the Figures is intended to accord with a possible embodiment. Further, wherever possible, the following description refers to the reference numerals included in the following Figures, in which features depicted in multiple Figures are designated with consistent reference numerals.

[0012] Figure 1 illustrates a diagram of a system for performing phase shift interferometry (“PSI”) to detect irregularities on a surface of a wafer.

[0013] Figure 2 illustrates a diagram of another system for performing phase shift interferometry (“PSI”) to detect irregularities on surfaces on both sides of a wafer both shown in Figure 1, simultaneously.

[0014] Figure 3 illustrates an image taken by the image capture device without a wafer shown in Figure 1.

[0015] Figure 4 illustrates an image taken by the image capture device with a wafer shown in Figure 1.

[0016] Figure 5 illustrates a process for interferometer cavity calibration and laser linearization in phase shift interferometry.

[0017] Figure 6 illustrates an example system for performing the process shown in Figure 5.

[0018] Figure 7 illustrates an example configuration of a user computer device.

[0019] Figure 8 illustrates an example configuration of a server computer device.

[0020] Like reference symbols in the various drawings indicate like elements.28744-6503 (231017.3) DETAILED DESCRIPTION

[0021] The field of the disclosure relates to interferometry images of semiconductor wafers and, more particularly, to systems and methods for interferometer cavity calibration and laser linearization in phase shift interferometry used for semiconductor wafer inspection and analysis. Furthermore, the present disclosure relate to systems and methods for performing phase shift interferometry (PSI) which enable eliminating regular cavity and laser calibration and the need for perfectly linear wavelength scans.

[0022] Embodiments of the present disclosure provide a method that is based on statistical analysis of fringe periods in every visible partial cavity pixel in continuous scanning PSI. The present disclosure facilitates the elimination of regular cavity and laser calibration by in-situ cavity calibration and laser linearization during every single measurement. This is done without any additional measurement. This methodology uses the data that is recorded normally during the course of a wafer measurement.

[0023] During a continuous scan PSI, the intensity scans of each partial cavity pixel are normalized to a range of + / - 1. Then the zero transitions of all partial cavity pixels are found, numbered, and together with their corresponding frame numbers, are statistically evaluated by polynomial regression analysis, modelling laser wavelength as polynomial function of control voltage or control current (depending on laser model).

[0024] Contrary to known methods, the systems and methods described herein implement an algorithm or model that makes it unnecessary to perform a calibration with the attempt to achieve a perfectly linear phase shift scan. Instead, the data of a scan is taken as is and the exact phase shifts per frame are calculated as they occurred. To eliminate the impact of potentially non-equidistant phase shifts between frames, the first derivative of the phase as function of frame number is applied as weight in subsequent data fitting algorithms.28744-6503 (231017.3)

[0025] Systems and methods implementing the algorithms of the present disclosure can be used for inspection of any suitable semiconductor wafer product. Such systems and methods may suitably be used to characterize wafer thickness, shape, flatness metrics, and nanotopography of the wafer. In some embodiments, the present disclosure can be implemented using a WaferSight tool (e.g., a WS1 generation interferometry tool) available from KLA-Tencor, Milpitas, CA.

[0026] Figure 1 illustrates a diagram of a system 100 for performing phase shift interferometry (“PSI”) to detect irregularities on a surface 125 of a wafer 124. System 100 includes an analyzer device 102 and an interferometer 110. Analyzer device 102 includes a plurality of computing devices, including a first computing device 104, a second computing device 106, and a third computing device 108. In other implementations, analyzer device 102 includes a different number of computing devices. Interferometer 110, which in at least some implementations, is a Fizeau interferometer, includes a light source 112, a first lens 114, a beam splitter 116, a reference plane 118, a second lens 120, and an image capture device 122, such as a camera. In operation, wafer 124, which is for example a silicon wafer, is placed opposite light source 112.

[0027] Reference plane 118, which is semi reflective, is disposed between light source 112 and wafer 124. Beam splitter 116 is disposed between light source 112 and reference plane 118. During operation of system 100, light source 112 emits a light beam 113, which passes through first lens 114. A first portion of light beam 113 is reflected by reference plane 118. A second portion is transmitted through semi-reflective reference plane 118 and reflected by surface 125 of wafer 124. Beam splitter 116 directs the reflected light 117 (e.g., the first portion and the second portion) towards image capture device 122. The reflected light 117 passes through second lens 120 to image capture device 122 which samples reflected light 117.

[0028] Analyzer device 102 is communicatively coupled to light source 112 and image capture device 122. More specifically, analyzer device 102 transmits light source instruction signals 126 to light source 112. Light source instruction signals 126 include light source instructions 128. Light source instructions28744-6503 (231017.3) 128 include a control function for cyclically emitting different wavelengths 130, for example as a function of time and / or a number of samples that have been obtained. In some implementations, wavelengths 130 is a range or set of wavelengths, and instructions 128 additionally include a currently selected wavelength 132, and a time period 133 during which light 113 is to be emitted at each of the wavelengths 130. Accordingly, light source 112 cycles through wavelengths 130, starting with selected wavelength 132, and emits each wavelength 130 for the time period 133. In at least some implementations, light source 112 transmits a response signal 134, for example acknowledging receipt of light source instruction signal 126.

[0029] Analyzer device 102 transmits image capture instruction signals 136 to image capture device 122. Image capture instruction signals 136 include image capture instructions 138. Image capture instructions 138 include an exposure time 140, representing an amount of time that image capture device 122 is to receive reflected light 117 to generate a sample 144. Image capture device 122 transmits image signals 142 to analyzer device 102. Image signals 142 include samples 144 generated by image capture device 122 by receiving reflected light 117 during exposure time 140. As described in more detail, image capture device 122 repeatedly captures reflected light 117 during repeated exposure times 140. Additionally, image capture device 122 performs the capture of reflected light 117 for each of a plurality of light sensors 123, for example charge coupled devices (CCDs), included in image capture device 122. Light sensors 123 are associated with respective pixels, described in more detail herein. While system 100 includes an interferometer 110, other implementations do not include interferometer 110 and instead project a moving fringe pattern (e.g., light 117) onto surface 125, as described in more detail herein.

[0030] Figure 2 illustrates a diagram of another system 200 for performing phase shift interferometry (“PSI”) to detect irregularities on surfaces 125 on both sides of a wafer 124 (both shown in Figure 1) simultaneously. In some embodiment, system 100 is a part of system 200. Whereas the inventive concept can be employed in conjunction with many types of temperature- and vibration-sensitive equipment (as an example, medical instrumentation), the invention will be illustrated herein with an embodiment directed to interferometric measurement systems. The28744-6503 (231017.3) embodiment of Figure 2 a takes advantage of an existing system that has skin panels 205 which enclose interferometers 110 to create an enclosed minienvironment having forced air circulation. This system 200 may be modified as follows: the air circulation unit 215 that delivers air into the cavity 220 may be modified such that the temperature and the speed of its output to the cavity 220 are controllable. The cavity 220 refers to the space between the two semi-transparent reference planes 118. Note that varying the speed of air circulation or the fan speed changes the amplitude and the frequency of the acoustic noise and mechanical vibration. Multiple temperature sensors 225 may be mounted on interferometers 110 or at any other positions where temperature control is desired. Thus the positioning of the sensors 225 can be customized according to the details of the measurement or metrology system within the cavity 220, to provide more accurate temperature feedback to control unit 230. A heating element 235 may be inserted between fan 240 and air filter 245 of unit 215. Optional cooling element 137 may be inserted at any position near air inlet 239. Computer 250 may connect to control unit 230, and may also be used for data acquisition. Control unit 230 controls heating element 235, cooling element 237, and speed of fan 240. In some embodiments, a single heating element 235 and a single cooling element 237 provides sufficient temperature control, and the multiple sensors 225 provide accurate temperature measurement at multiple points of interest.

[0031] Note that the configuration shown in Figures 1 and 2 are exemplary and not limiting. For example, in contrast to how it is shown in FIG.2, the fan that blows air into the mini-cavity 220 is not required to be directly at an opening, i.e., proximal, to the mini-cavity 220. It can be placed in a position removed from the mini-cavity 220, and a duct (not shown) can be used to bring air into the mini-cavity 220. In such a case, the air circulation would still cause vibration and acoustic noise.

[0032] Figure 3 illustrates an image 300 taken by the image capture device 122 without a wafer 124 (both shown in Figure 1). More specifically, image 300 shows the background 305 of the cavity 220 (shown in Figure 2). The background 305 of the cavity 220 has the potential to change over time due to temperature and other factors. Accordingly, the systems and methods described herein are configured to account for those changes in real-time.28744-6503 (231017.3)

[0033] Figure 4 illustrates an image 400 taken by the image capture device 122 with a wafer 124 (both shown in Figure 1). More specifically, image 400 shows the wafer image 405 of the wafer 124. Image 400 also includes the background 305 (shown in Figure 3) of the cavity 220 (shown in Figure 2) in a ring 410 around the wafer image 405. Image 400 also includes the wafer grippers 415 that hold the wafer 124 vertically. The wafer image 405 and the background ring image 410 are used with the systems and methods described herein.

[0034] The background 305 of the cavity 220 has the potential to change over time due to temperature and other factors. Accordingly, the systems and methods described herein are configured to account for those changes in real-time.

[0035] Figure 5 illustrates a process 500 for interferometer cavity calibration and laser linearization in phase shift interferometry. In the example embodiment, process 500 is performed by the constant calibration server 610 (shown in Figure 6).

[0036] In the exemplary embodiment, the constant calibration server 610 receives 505 a plurality of images for a continuous scan phase shift interferometry. The plurality of images are of a surface, potentially of a semiconductor wafer. Each of the plurality of images include a first plurality of pixels of the wafer 124 (shown in Figure 1). The plurality of images also include a second plurality of pixels of the cavity, aka the background 305 (shown in Figure 3) of the cavity 220 (shown in Figure 2) in a ring 410 around the wafer image 405 (both shown in Figure 4). In some embodiments, the ring image 410 view of the background 305 of the cavity 220 is also known as a partial cavity.

[0037] In the exemplary embodiment, the constant calibration server 610 performs 510 intensity scans of each pixel in the second plurality of pixels. The calibration server 610 normalizes the second plurality of pixels into a range of + / - 1.

[0038] In the exemplary embodiment, the constant calibration server 610 identifies zero transitions for each of the second plurality of pixels. A zero transition occurs when the normalized value of a pixel changes from a positive to a28744-6503 (231017.3) negative value or from a negative value to a positive value. The zero transitions are identified with their corresponding frame numbers. For the purposes of this discussion, frame numbers are an image’s position in the sequence.

[0039] In the exemplary embodiment, the constant calibration server 610 statistically evaluates the identified zero transitions and corresponding frame numbers by polynomial regression analysis. In some embodiments, the laser wavelength is modeled as polynomial function of control voltage or control current. This depends on the corresponding laser model. This procedure yields the exact relation between frame number and laser wavelength at the time of measurement. It is exact in the sense, that any temperature effect on the reference plane's relative position happens so slowly, that it is negligible during the short time of the measurement. Since it is taken at the same time as the wafer, it can then be used for analyzing the wafer's front and back surfaces, which may change their shape and relative position in the cavity during measurement due to temperature changes the wafer experiences when being moved from the cassette into the cavity.

[0040] In one example embodiment, the cavity is 50 mm. (Question for the Inventors: Is this the size between the edge of the wafer and the end of the image? Or is it the amount of cavity shown on each line from one edge of the image toB85 >B85@+#% -85 E1D5;5=7B8 "I# 9A )'& =<% ,= B89A 5F1<?;5$ >=5 6@9=75 ?5@9>43>@@5A?>=4A B> 1 HI >6 '%* ?<% ,= B89A 5F1<?;5$ B85 BG?931; E1D5;5=7B8381=75 >D5@ 1full scan is 16 pm. The typical current tuning coefficient is 1 pm / mA. This means that changing the wavelength by current would require a change of 16 mA.

[0041] The constant calibration computer device 610 approximates IN (normalized intensity) as a function of frame index f, where $& = #13[6 - (1 + ( - + ) -: + * -;) + 8] EQ. 1

[0042] The zero transition i will be at: 0= #13[6 - (1 + ( - + ) -: + * -;) + 8] EQ. 228744-6503 (231017.3) 11H where - : is chosen to start counting the zero transitions at i=1. In addition, phase shift 8 is substituted by zero transition phase shift: 5= %1+[8, 4] +H : EQ.4 Accordingly, the zero transitions are numbered starting with 1, regardless of whether it is a rising or falling transition. This leads to:with fi,k the frame index (fi,k $ 0...255) of zero transition ik, where (ik = 1...z) at a pixelk and zero transition phase shift 5G at pixel k. INk 1=4 HINk are the normalized intensityand its derivative at frame 0 at pixel k. Thusfor all zero transitions, numbering zero transitions i from 1...z.

[0043] The phase shift isand the zero transition phase shift is / &&((0 .9B8 C=:=>E= ?1@1<5B5@A / J$ 1$ 2$ 301=45AB9<1B545G (basedon normalized intensity and derivative must fit all sets of [ik, fi,k].28744-6503 (231017.3)from this, the constant calibration computer device 610 calculated the parameters of approximation by solving the following matrix equation. (Lower triangle values have been omitted, since the matrix is symmetric.)is the sum over all found zero transitions i of pixel k andis the over all pixels.28744-6503 (231017.3)

[0045] While the above describes using the systems and processes described herein for analyzing silicon wafers, one having ordinary skill in the art would understand that these systems and methods may also be used for analyzing other surfaces.

[0046] Figure 6 illustrates an example system 600 for performing the process 500 (shown in Figure 5). In the example embodiment, the system 600 is used for interferometer cavity calibration and laser linearization in phase shift interferometry.

[0047] As described below in more detail, a constant calibration server 610 is programmed to interferometer cavity calibration and laser linearization in phase shift interferometry. The constant calibration server 610 is programmed to a) receive 505 a plurality of images for a continuous scan phase shift interferometry; perform 510 intensity scans of each pixel in the second plurality of pixels; identify 515 zero transitions for each of the second plurality of pixels; and statistically evaluate 520 the identified zero transitions and corresponding frame numbers by polynomial regression analysis (as shown in Figure 5).

[0048] In the example embodiment, client devices 605 are computers that include a web browser or a software application, which enables client devices 605 to communicate with constant calibration server 610 using the Internet, a local area network (LAN), or a wide area network (WAN). In some embodiments, the client devices 605 are communicatively coupled to the Internet through many interfaces including, but not limited to, at least one of a network, such as the Internet, a LAN, a WAN, or an integrated services digital network (ISDN), a dial-up-connection, a digital subscriber line (DSL), a cellular phone connection, a satellite connection, and a cable modem. Client devices 605 can be any device capable of accessing a network, such as the Internet, including, but not limited to, a desktop computer, a laptop computer, a personal digital assistant (PDA), a cellular phone, a smartphone, a tablet, a phablet, wearable electronics, smart watch, virtual headsets or glasses (e.g., AR (augmented reality), VR (virtual reality), or XR (extended reality) headsets or glasses), chat bots,28744-6503 (231017.3) voice bots, ChatGPT bots or ChatGPT-based bots, or other web-based connectable equipment or mobile devices.

[0049] In the example embodiment, constant calibration computer device 610 (also known as constant calibration server 610) is a computer that include a web browser or a software application, which enables constant calibration server 610 to communicate with client devices 605 and cameras / sensors 625 using the Internet, a local area network (LAN), or a wide area network (WAN). In some embodiments, the constant calibration server 610 is communicatively coupled to the Internet through many interfaces including, but not limited to, at least one of a network, such as the Internet, a LAN, a WAN, or an integrated services digital network (ISDN), a dial-up- connection, a digital subscriber line (DSL), a cellular phone connection, a satellite connection, and a cable modem. The constant calibration server 610 can be any device capable of accessing a network, such as the Internet, including, but not limited to, a desktop computer, a laptop computer, a personal digital assistant (PDA), a cellular phone, a smartphone, a tablet, a phablet, wearable electronics, smart watch, virtual headsets or glasses (e.g., AR (augmented reality), VR (virtual reality), or XR (extended reality) headsets or glasses), chat bots, voice bots, ChatGPT bots or ChatGPT-based bots, or other web-based connectable equipment or mobile devices. In some embodiments, the constant calibration server 610 includes one or more of the analyzer device 102, the first computing device 104, the second computing device 106, and the third computing device 108 (all shown in Figure 1).

[0050] A database server 615 is communicatively coupled to a database 620 that stores data. In one embodiment, the database 620 is a database that includes a plurality of images from scans. In some embodiments, the database 620 is stored remotely from the constant calibration server 610. In some embodiments, the database 620 is decentralized. In the example embodiment, a person can access the database 620 via the client devices 605 by logging onto constant calibration server 610.

[0051] Camera / sensor 625 may be any camera and / or sensor that the constant calibration server 610 is in communication with that transmits images to the constant calibration server 610, such as the image capture device 122 (shown in Figure28744-6503 (231017.3) 1). In the example embodiment, camera / sensors 625 that are in communication with constant calibration server 610 using the Internet, a local area network (LAN), or a wide area network (WAN). In some embodiments, the camera / sensor(s) 625 are communicatively coupled to the Internet through many interfaces including, but not limited to, at least one of a network, such as the Internet, a LAN, a WAN, or an integrated services digital network (ISDN), a dial-up-connection, a digital subscriber line (DSL), a cellular phone connection, a satellite connection, and a cable modem.

[0052] Figure 7 depicts an example configuration 700 of user computer device 702. In the example embodiment, user computer device 702 may be similar to, or the same as, client device 605 (shown in Figure 6). User computer device 702 may be operated by a user 701.

[0053] User computer device 702 may include a processor 705 for executing instructions. In some embodiments, executable instructions may be stored in a memory area 710. Processor 705 may include one or more processing units (e.g., in a multi-core configuration). Memory area 710 may be any device allowing information such as executable instructions and / or transaction data to be stored and retrieved. Memory area 710 may include one or more computer readable media.

[0054] User computer device 702 may also include at least one media output component 715 for presenting information to user 701. Media output component 715 may be any component capable of conveying information to user 701. In some embodiments, media output component 715 may include an output adapter (not shown) such as a video adapter and / or an audio adapter. An output adapter may be operatively coupled to processor 705 and operatively couplable to an output device such as a display device (e.g., a cathode ray tube (CRT), liquid crystal display (LCD), light emitting diode (LED) display, or “electronic ink” display) or an audio output device (e.g., a speaker or headphones).

[0055] In some embodiments, media output component 715 may be configured to present a graphical user interface (e.g., a web browser and / or a client application) to user 701. A graphical user interface may include, for example, an28744-6503 (231017.3) interface for viewing items of information provided by the constant calibration server 610 (shown in Figure 6). In some embodiments, user computer device 702 may include an input device 720 for receiving input from user 701. User 701 may use input device 720 to, without limitation, submit information either through speech or typing.

[0056] Input device 720 may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, a biometric input device, and / or an audio input device. A single component such as a touch screen may function as both an output device of media output component 715 and input device 720.

[0057] User computer device 702 may also include a communication interface 725, communicatively coupled to a remote device such as constant calibration server 610. Communication interface 725 may include, for example, a wired or wireless network adapter and / or a wireless data transceiver for use with a mobile telecommunications network.

[0058] Stored in memory area 710 are, for example, computer readable instructions for providing a user interface to user 701 via media output component 715 and, optionally, receiving and processing input from input device 720. A user interface may include, among other possibilities, a web browser and / or a client application. Web browsers enable users, such as user 701, to display and interact with media and other information typically embedded on a web page or a website from constant calibration server 610. A client application may allow user 701 to interact with, for example, constant calibration server 610. For example, instructions may be stored by a cloud service, and the output of the execution of the instructions sent to the media output component 715.

[0059] Figure 8 depicts an example configuration 800 of a server computer device 802. In the example embodiment, server computer device 802 may be similar to, or the same as, constant calibration server 610 and database server 615 (both shown in Figure 6). Server computer device 802 may also include a processor 805 for executing instructions. Instructions may be stored in a memory area 810.28744-6503 (231017.3) Processor 805 may include one or more processing units (e.g., in a multi-core configuration).

[0060] Processor 805 may be operatively coupled to a communication interface 815 such that server computer device 802 is capable of communicating with a remote device such as another server computer device 802, constant calibration server 610, camera / sensors 625, and client devices 605 (shown in Figure 6) (for example, using wireless communication or data transmission over one or more radio links or digital communication channels). For example, communication interface 815 may receive input from client devices 605 via the Internet, as illustrated in Figure 6.

[0061] Processor 805 may also be operatively coupled to a storage device 825. Storage device 825 may be any computer-operated hardware suitable for storing and / or retrieving data, such as, but not limited to, data associated with one or more models. In some embodiments, storage device 825 may be integrated in server computer device 802. For example, server computer device 802 may include one or more hard disk drives as storage device 825.

[0062] In other embodiments, storage device 825 may be external to server computer device 802 and may be accessed by a plurality of server computer devices 802. For example, storage device 825 may include a storage area network (SAN), a network attached storage (NAS) system, and / or multiple storage units such as hard disks and / or solid-state disks in a redundant array of inexpensive disks (RAID) configuration.

[0063] In some embodiments, processor 805 may be operatively coupled to storage device 825 via a storage interface 820. Storage interface 820 may be any component capable of providing processor 805 with access to storage device 825. Storage interface 820 may include, for example, an Advanced Technology Attachment (ATA) adapter, a Serial ATA (SATA) adapter, a Small Computer System Interface (SCSI) adapter, a RAID controller, a SAN adapter, a network adapter, and / or any component providing processor 805 with access to storage device 825.28744-6503 (231017.3)

[0064] Processor 805 may execute computer-executable instructions for implementing aspects of the disclosure. In some embodiments, the processor 805 may be transformed into a special purpose microprocessor by executing computer- executable instructions or by otherwise being programmed. For example, the processor 805 may be programmed with the instruction such as illustrated in Figure 5.

[0065] At least one of the technical problems addressed by this system may include: (i) improve analysis of wafers; (ii) decreased loss of material due to malfunction; (iii) earlier determination of wafer quality; (iv) increased accuracy in wafer analysis; and / or (v) increased accuracy in wafer analysis.

[0066] A technical effect of the systems and processes described herein may be achieved by performing at least one of the following steps: (a receive a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; b) perform intensity scans of each pixel in the second plurality of pixels; c) identify zero transitions for each of the second plurality of pixels; d) statistically evaluate the identified zero transitions by polynomial regression analysis; e) wherein the plurality of images are of a surface; f) wherein the surface is of a semiconductor wafer; g) wherein the first plurality of pixels are of the surface; h) wherein the second plurality of pixels of the partial cavity around the surface; i) wherein the at least one processor is further programmed to normalize the second plurality of pixels into a range of + / - 1; j) wherein the zero transitions are identified with their corresponding frame numbers; k) statistically evaluate the identified zero transitions and corresponding frame numbers by polynomial regression analysis; and / or l) model a laser wavelength as polynomial function of at least one of control voltage and control current. ADDITIONAL CONSIDERATIONS

[0067] As will be appreciated based upon the foregoing specification, the above-described embodiments of the disclosure may be implemented using computer programming or engineering techniques including computer software,28744-6503 (231017.3) firmware, hardware or any combination or subset thereof. Any such resulting program, having computer-readable code means, may be embodied or provided within one or more computer-readable media, thereby making a computer program product, i.e., an article of manufacture, according to the discussed embodiments of the disclosure. The computer-readable media may be, for example, but is not limited to, a fixed (hard) drive, diskette, optical disk, magnetic tape, semiconductor memory such as read-only memory (ROM), and / or any transmitting / receiving medium such as the Internet or other communication network or link. The article of manufacture containing the computer code may be made and / or used by executing the code directly from one medium, by copying the code from one medium to another medium, or by transmitting the code over a network.

[0068] These computer programs (also known as programs, software, software applications, “apps,” or code) include machine instructions for a programmable processor and can be implemented in a high-level procedural and / or object-oriented programming language, and / or in assembly / machine language. As used herein, the terms “machine-readable medium” “computer-readable medium” refers to any computer program product, apparatus and / or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The “machine-readable medium” and “computer-readable medium,” however, do not include transitory signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0069] As used herein, the terms “processor” and “computer” and related terms, e.g., “processing device”, “computing device”, and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a microcontroller, a microcomputer, a programmable logic controller (PLC), a reduced instruction set circuit (RISC), an application specific integrated circuit (ASIC), logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are example only and are thus not intended to limit in any way the definition and / or meaning of the term “processor.”28744-6503 (231017.3)

[0070] As used herein, the terms “software” and “firmware” are interchangeable, and include any computer program stored in memory for execution by a processor, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are example only, and are thus not limiting as to the types of memory usable for storage of a computer program.

[0071] As used herein, the term “database” can refer to either a body of data, a relational database management system (RDBMS), or to both. As used herein, a database can include any collection of data including hierarchical databases, relational databases, flat file databases, object-relational databases, object-oriented databases, and any other structured collection of records or data that is stored in a computer system. The above examples are example only, and thus are not intended to limit in any way the definition and / or meaning of the term database. Examples of RDBMS’ include, but are not limited to including, Oracle® Database, MySQL, IBM® DB2, Microsoft® SQL Server, Sybase®, and PostgreSQL. However, any database can be used that enables the systems and methods described herein. (Oracle is a registered trademark of Oracle Corporation, Redwood Shores, California; IBM is a registered trademark of International Business Machines Corporation, Armonk, New York; Microsoft is a registered trademark of Microsoft Corporation, Redmond, Washington; and Sybase is a registered trademark of Sybase, Dublin, California.)

[0072] In another example, a computer program is provided, and the program is embodied on a computer-readable medium. In an example, the system is executed on a single computer system, without requiring a connection to a server computer. In a further example, the system is being run in a Windows® environment (Windows is a registered trademark of Microsoft Corporation, Redmond, Washington). In yet another example, the system is run on a mainframe environment and a UNIX® server environment (UNIX is a registered trademark of X / Open Company Limited located in Reading, Berkshire, United Kingdom). In a further example, the system is run on an iOS® environment (iOS is a registered trademark of Cisco Systems, Inc. located in San Jose, CA). In yet a further example, the system is run on a Mac OS® environment (Mac OS is a registered trademark of Apple Inc. located in Cupertino,28744-6503 (231017.3) CA). In still yet a further example, the system is run on Android® OS (Android is a registered trademark of Google, Inc. of Mountain View, CA). In another example, the system is run on Linux® OS (Linux is a registered trademark of Linus Torvalds of Boston, MA). The application is flexible and designed to run in various different environments without compromising any major functionality.

[0073] As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “example” or “one example” of the present disclosure are not intended to be interpreted as excluding the existence of additional examples that also incorporate the recited features. Further, to the extent that terms “includes,” “including,” “has,” “contains,” and variants thereof are used herein, such terms are intended to be inclusive in a manner similar to the term “comprises” as an open transition word without precluding any additional or other elements.

[0074] Furthermore, as used herein, the term “real-time” refers to at least one of the time of occurrence of the associated events, the time of measurement and collection of predetermined data, the time to process the data, and the time of a system response to the events and the environment. In the examples described herein, these activities and events occur substantially instantaneously.

[0075] In some embodiments, the system includes multiple components distributed among a plurality of computer devices. One or more components may be in the form of computer-executable instructions embodied in a computer-readable medium. The systems and processes are not limited to the specific embodiments described herein. In addition, components of each system and each process can be practiced independent and separate from other components and processes described herein. Each component and process can also be used in combination with other assembly packages and processes. The present embodiments may enhance the functionality and functioning of computers and / or computer systems.28744-6503 (231017.3)

[0076] The computer-implemented methods discussed herein can include additional, less, or alternate actions, including those discussed elsewhere herein. The methods can be implemented via one or more local or remote processors, transceivers, servers, and / or sensors (such as processors, transceivers, servers, and / or sensors mounted on vehicles or mobile devices, or associated with smart infrastructure or remote servers), and / or via computer-executable instructions stored on non- transitory computer-readable media or medium. Additionally, the computer systems discussed herein can include additional, less, or alternate functionality, including that discussed elsewhere herein. The computer systems discussed herein can include or be implemented via computer-executable instructions stored on non-transitory computer- readable media or medium.

[0077] As used herein, the term “non-transitory computer-readable media” is intended to be representative of any tangible computer-based device implemented in any method or technology for short-term and long-term storage of information, such as, computer-readable instructions, data structures, program modules and sub-modules, or other data in any device. Therefore, the methods described herein can be encoded as executable instructions embodied in a tangible, non-transitory, computer readable medium, including, without limitation, a storage device and / or a memory device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein. Moreover, as used herein, the term “non-transitory computer-readable media” includes all tangible, computer- readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and nonvolatile media, and removable and non- removable media such as a firmware, physical and virtual storage, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, as well as yet to be developed digital means, with the sole exception being a transitory, propagating signal.

[0078] The patent claims at the end of this document are not intended to be construed under 35 U.S.C. § 112(f) unless traditional means-plus-function language is expressly recited, such as “means for” or “step for” language being expressly recited in the claim(s).28744-6503 (231017.3)

[0079] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

28744-6503 (231017.3) WHAT IS CLAIMED IS:

1. A computer device comprising at least one processor in communication with at least one memory device, wherein the at least one processor programmed to: receive a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; perform intensity scans of each pixel in the second plurality of pixels; identify zero transitions for each of the second plurality of pixels; and statistically evaluate the identified zero transitions by polynomial regression analysis.

2. The computer device of Claim 1, wherein the plurality of images are of a surface.

3. The computer device of Claim 2, wherein the surface is of a semiconductor wafer.

4. The computer device of Claim 2, wherein the first plurality of pixels are of the surface.

5. The computer device of Claim 2, wherein the second plurality of pixels of the partial cavity around the surface.

6. The computer device of Claim 1, wherein the at least one processor is further programmed to normalize the second plurality of pixels into a range of + / - 1.

7. The computer device of Claim 1, wherein the zero transitions are identified with their corresponding frame numbers.28744-6503 (231017.3) 8. The computer device of Claim 7, wherein the at least one processor is further programmed to statistically evaluate the identified zero transitions and corresponding frame numbers by polynomial regression analysis.

9. The computer device of Claim 1, where the at least one processor is further programmed to model a laser wavelength as polynomial function of at least one of control voltage and control current.

10. A system for interferometer cavity calibration and laser linearization in phase shift interferometry, the system comprising: a light source; an image capture device to capture images illuminated by the light source; and a computer device comprising at least one processor in communication with at least one memory device, wherein the at least one processor programmed to: receive, from the image capture device, a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; perform intensity scans of each pixel in the second plurality of pixels; identify zero transitions for each of the second plurality of pixels; and statistically evaluate the identified zero transitions by polynomial regression analysis.

11. The system of Claim 10, wherein the plurality of images are of a surface.

12. The system of Claim 11, wherein the surface is of a semiconductor wafer.28744-6503 (231017.3) 13. The system of Claim 11, wherein the first plurality of pixels are of the surface.

14. The system of Claim 11, wherein the second plurality of pixels of the partial cavity around the surface.

15. The system of Claim 10, wherein the at least one processor is further programmed to normalize the second plurality of pixels into a range of + / - 1.

16. The system of Claim 10, wherein the zero transitions are identified with their corresponding frame numbers.

17. The system of Claim 16, wherein the at least one processor is further programmed to statistically evaluate the identified zero transitions and corresponding frame numbers by polynomial regression analysis.

18. The system of Claim 10, where the at least one processor is further programmed to model a laser wavelength as polynomial function of at least one of control voltage and control current.

19. A computer-implemented method performed by a computer system including at least one processor in communication with a chatbot and at least one memory device, the method comprising: receiving a plurality of images for a continuous scan phase shift interferometry (PSI), wherein each image of the plurality of images includes a first plurality of pixels of a first item and a second plurality of pixels of a partial cavity; performing intensity scans of each pixel in the second plurality of pixels; identifying zero transitions for each of the second plurality of pixels; and statistically evaluating the identified zero transitions by polynomial regression analysis.28744-6503 (231017.3) 20. The computer-implemented method of Claim 19, wherein the plurality of images are of a surface of a semiconductor wafer, wherein the first plurality of pixels are of the surface; and wherein the second plurality of pixels of the partial cavity around the surface.

Images