Noise diagnostics for electron beam inspection systems using swathing.

Abstract

Parameters from the inspection image representing mechanical vibration and electromagnetic interference can be determined. An X-direction vibration spectrum can be determined based on an X-direction offset. A Y-direction vibration spectrum can be determined based on a Y-direction offset. The determination can be based on a swath image of a workpiece, such as a semiconductor wafer or reticle.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to inspection of workpieces. [Background technology]

[0002] Evolution in the semiconductor manufacturing industry places greater demands on yield management, particularly on metrology and inspection systems. While critical dimensions continue to shrink, the industry needs to decrease the time to achieve high-yield, high-value production. Minimizing the total time from detecting a yield problem to correcting it maximizes the return on investment for semiconductor manufacturers.

[0003] The fabrication of semiconductor devices, such as logic and memory devices, typically involves processing semiconductor wafers using a number of manufacturing processes to form various features and levels of the semiconductor devices. For example, lithography is a semiconductor manufacturing process that involves transferring a pattern from a reticle to a photoresist disposed on a semiconductor wafer. Additional examples of semiconductor manufacturing processes include, but are not limited to, chemical mechanical polishing (CMP), etching, deposition, and ion implantation. The arrangement of multiple semiconductor devices fabricated on a single semiconductor wafer can be separated into individual semiconductor devices.

[0004] Inspection processes are used to detect defects on wafers at various steps during semiconductor manufacturing to promote higher yields in the manufacturing process, and therefore higher profits. Inspection has always been an important part of manufacturing semiconductor devices, such as integrated circuits (ICs). However, as the dimensions of semiconductor devices decrease, inspection becomes even more important for the successful manufacture of acceptable semiconductor devices, as smaller defects can cause the devices to fail. For example, as the dimensions of semiconductor devices decrease, detection of increasingly smaller defects has become necessary, as even relatively small defects can cause undesirable anomalies in the semiconductor devices.

[0005] However, as design rules become smaller, semiconductor manufacturing processes may be operating closer to the limits of their performance capabilities. Additionally, as design rules become smaller, resulting in more sensitive inspection, smaller defects may affect device electrical parameters. As design rules become smaller, the number of potentially yield-relevant defects detected by inspection increases dramatically, as does the number of nuisance defects detected by inspection. Therefore, more defects may be detected on a wafer, and correcting the process to remove all of the defects may be difficult and expensive. Determining which defects are actually affecting device electrical parameters and yield may allow process control methods to focus on those defects while largely ignoring others. Furthermore, with smaller design rules, process-induced failures may in some cases tend to be systematic. That is, process-induced failures tend to fail in predetermined design patterns that are often repeated many times within a design. Removing spatially systematic, electrically related defects may affect yield.

[0006] Electron beam inspection is often used in semiconductor metrology for high-resolution microscopic examination of layers within semiconductor devices. Electron beams have several advantages over other mechanisms for inspecting or otherwise testing specimens. While optical beams have an intrinsic resolution limit of approximately 100 nm to 200 nm, electron beams can investigate feature sizes as small as a few nanometers.

[0007] One particular problem with electron beam inspection systems is system noise in acquired images caused by system disturbances. Specifically, mechanical vibrations such as tool jitter and electromagnetic interference can affect inspection. Obtaining the frequency associated with such vibrations can be advantageous, and such vibrations can be used as tool diagnostics for troubleshooting electron beam inspection tools. The frequency and amplitude of tool vibrations can be measured during the step-and-settle mode of operation of an electron beam inspection tool, which requires the electron beam to scan over a linear edge pattern on the wafer with the scan direction perpendicular to the edge. Furthermore, this technique requires the stage to remain stationary while the scan is performed. This technique is not applicable to the swath mode of operation, in which the electron beam scans in a raster pattern while the stage and wafer move at a constant speed.

[0008] Another technique for measuring vibration frequency based on swath images uses kernel alignment. This technique detects the position offset of the kernel with respect to time in the swath image. This method is disadvantageous because it is sensitive to the pattern, dimensions, and distortion of the swath image. Furthermore, this method is computationally expensive. It can take more than 10 minutes to complete a single image, which can disrupt inspection throughput when combined into a large swath image. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2021 / 038633 [Patent Document 2] U.S. Patent Application Publication No. 2010 / 0224792 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, a solution is needed to obtain information about system noise (including mechanical vibrations and electromagnetic interference (EMI)) from the inspection tool during beam-swathing imaging mode in order to diagnose image quality problems related to tool vibrations. [Means for solving the problem]

[0011] In a first embodiment, a system is provided. The system includes a particle beam source that generates a beam of particles (e.g., electrons), a stage configured to hold a workpiece in the path of the particle beam, a detector configured to receive the particle beam reflected from the workpiece, and a processor in electronic communication with the detector. The processor is configured to receive an image of the workpiece, determine an X-direction profile of the image, determine an X-direction offset for the semiconductor wafer between a nominal cell size and the profile, and determine a vibration spectrum in the X-direction based on the X-direction offset. The image includes an array of patterns on the workpiece. The X-direction profile includes edges of the patterns across the X-direction.

[0012] The processor may be further configured to crop the image into swaths of the pattern, wherein a swath in the image may comprise two or more columns in the array.

[0013] The processor may be further configured to determine a Y-direction profile of the image, determine a Y-direction offset for the workpiece between the nominal line and the profile, and determine a vibration spectrum in the Y-direction based on the Y-direction offset. The Y-direction profile includes an edge of the pattern across the Y-direction. The Y-direction is orthogonal to the X-direction. A swath in the image may include two or more rows in the array.

[0014] The processor may be further configured to average the X direction vibration spectrum and the Y direction vibration spectrum and determine a vibration frequency for the system from the averaging.

[0015] The workpiece may be a semiconductor wafer or a reticle.

[0016] In a second embodiment, a method is provided. The method includes receiving, at a processor, an image of a workpiece generated by an inspection system. The image includes an array of patterns on the workpiece. Using the processor, an X-direction profile of the image is determined. The X-direction profile includes edges of the patterns across the X-direction. Using the processor, an X-direction offset for the workpiece between a nominal cell size and the profile is determined. Using the processor, a vibration spectrum in the X-direction is determined based on the X-direction offset.

[0017] The method may further include generating an image using the inspection system.

[0018] The inspection system may be a scanning electron microscope.

[0019] The method may include using a processor to crop the image into swaths of the pattern. A swath in the image may include two or more columns in the array.

[0020] The method may further include using a processor to determine a Y-direction profile of the image. The Y-direction profile includes the edges of the pattern across the Y direction. The Y-direction is orthogonal to the X-direction. In Figures 3, 6, and 9, the X-direction is horizontal and the Y-direction is vertical, but these directions may be reversed depending on the image and / or workpiece. Using the processor, a Y-direction offset for the workpiece between the nominal line and the profile is determined. Using the processor, a vibration spectrum in the Y-direction based on the Y-direction offset is determined. A swath in the image includes two or more rows in the array.

[0021] The method can include averaging the X-direction vibration spectrum and the Y-direction vibration spectrum and determining a vibration frequency for the inspection system from the averaging using a processor.

[0022] The workpiece may be a semiconductor wafer or a reticle.

[0023] A non-transitory computer-readable medium may store a program configured to instruct a processor to perform some or all of the steps of the second embodiment.

[0024] For a fuller understanding of the nature and objects of the present disclosure, reference should be had to the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a flowchart of a method for determining an oscillation frequency of an electron beam inspection tool. [Figure 2] FIG. 2 is an illustration of a raster scan as described in one of the embodiments. [Figure 3] FIG. 1 is an explanatory diagram of an array pattern on a semiconductor wafer. [Figure 4] FIG. 1 illustrates the nominal peak of a raster scan in an array pattern. [Figure 5]FIG. 1 illustrates the calculation of nominal frequency from a nominal peak versus time signal using an FFT. [Figure 6] FIG. 10 illustrates vertical edge detection during scanning in the X direction. [Figure 7] FIG. 10 shows the time domain signal of peak deviation in the X direction scan versus time. [Figure 8] FIG. 10 shows an FFT of the time domain signal of peak deviation in the X direction scan versus time. [Figure 9] FIG. 10 illustrates horizontal edge detection during scanning in the Y direction. [Figure 10] FIG. 10 shows the time domain signal of peak deviation in a Y direction scan versus time. [Figure 11] FIG. 10 is a diagram showing horizontal vibration frequency versus frequency. [Figure 12] FIG. 1 is a diagram of one embodiment of an inspection system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0026] Although the claimed subject matter is described in terms of several embodiments, other embodiments, including embodiments that do not provide all of the benefits and features described herein, are also within the scope of this disclosure. Various structural, logical, process step, and electronic changes may be made without departing from the scope of the disclosure. Accordingly, the scope of the disclosure is defined solely by reference to the appended claims.

[0027] Removal of tool-induced noise can improve the signal-to-noise ratio of electron beam inspection images. This can be achieved by determining parameters from the inspection image that represent mechanical vibrations and electromagnetic interference. Specifically, noise induced by such vibrations can be successfully isolated from the image using its characteristic frequencies. These calculated frequencies can be used as tool diagnostics during inspection tool evaluation to further characterize the vibration source. For example, low-frequency noise can be induced by the wafer stage, which can affect inspection.

[0028] The embodiments disclosed herein can obtain system noise information (including mechanical vibration and EMI) from an electron beam inspection tool during electron beam swath imaging mode to diagnose vibration-related image quality problems. In one example, no additional equipment is installed to perform the embodiments disclosed herein. The edge detection embodiments disclosed herein can recognize pattern edges and generate time-domain and frequency-domain spectra. Glitches or spurious edges can be determined to reduce spurious results caused by post-processing. Measurements in the Y direction (e.g., along the swath direction) can extend the bandwidth when straight features are detected in the swath image.

[0029] 1 shows a flowchart of method 100. Some or all of the steps in method 100 may be performed by a processor. An inspection system may generate the images used in method 100. For example, the inspection system may be a scanning electron microscope (SEM) or another inspection system that uses an electron beam. The electron beam inspection tool may be configured to operate in swath mode.

[0030] At 101, an image of a workpiece generated by an inspection system is received at a processor. The image may include an array of patterns on the workpiece. In one example, a raster scan is performed using the electron beam inspection system to acquire a swath image of the array pattern on the workpiece. The workpiece may be a semiconductor wafer or a reticle.

[0031] The image may be cropped into swaths of patterns. For example, a swath may have two or more columns in the array. For example, Figure 3 shows six columns extending vertically.

[0032] Swathing is an operating mode of electron beam imaging in which the electron beam scans in a raster pattern while the stage and workpiece move at a constant speed to match the scanning velocity of the electron beam. Figure 2 shows an exemplary illustration of raster scanning. As shown in Figure 2, during raster scanning, the inspection system moves over a scan line for a set distance and time before returning to the start of the next scan line.

[0033] Returning to FIG. 1 , at 102, an X-direction profile of the image is determined. The X-direction profile includes the edges of the pattern across the X-direction. The pattern may be an array of periodically repeating patterns on the workpiece. The patterns may be separated from each other by a pitch. In one embodiment, the pitch may be uniform. In another embodiment, the pitch may be irregular. FIG. 3 shows an illustration of an array pattern on a workpiece. Grayscale differences in the image may be used to generate a profile and determine edge locations and / or nominal patterns. Differences in brightness between adjacent pixels may indicate edges of the pattern.

[0034] Image condition information and array pattern information may be determined for the image. A nominal cell size may be estimated based on the image condition information and the array pattern information. These conditions may be determined through user input or from an algorithm that processes the image. For example, an algorithm may acquire swath images on a certain wafer pattern using certain imaging conditions for vibration analysis, and those conditions may be stored in a format that is passed to the analysis algorithm. A nominal peak of the raster scan may be determined for each array pattern within the nominal cell. The nominal peak may be any repeating feature identifiable from the acquired image. A time-domain signal of the nominal peak may be generated. A fast Fourier transform (FFT) may be performed on the time-domain signal to obtain the nominal frequency.

[0035] The image condition information may include pixel size and / or scan line time. The array pattern information may include the pitch between two repeating patterns. The image condition information and array pattern information may be provided manually by the user. This information may also be obtained from historical data from previous inspections.

[0036] Edge detection may be performed on the image to obtain the actual edge locations of the array pattern on the workpiece.

[0037] The nominal cell size may be determined based on image condition information and array pattern information. The nominal cell size may be estimated based on a predetermined number of pixels in the image. In one embodiment, the nominal cell size may be an array of individual pixels. The nominal cell size may be estimated based on the time each line in a raster scan is scanned before the electron beam inspection tool returns to the start position of the subsequent scan. In one embodiment, one of the nominal cell dimensions may be a multiple of the length of a raster scan line. The nominal cell size may also be estimated based on the array pattern pitch between repeating patterns. In one embodiment of the present disclosure, the pitch may be assigned to be uniform for the purpose of estimating the nominal cell size.

[0038] A nominal peak for each array pattern of the workpiece within a nominal cell can be determined. This nominal peak can be the peak distance traveled by the inspection system for each line of a swath-mode raster scan under nominal conditions. In one embodiment, nominal conditions can be assumed to estimate the nominal frequency and nominal peak. Thus, the first scan line of the inspection system's raster scan can be aligned with an edge of one of the array patterns, and the array patterns can be assumed to have a uniform pitch such that the deviation of each scan line of the inspection system's raster scan from the respective edge of the target array pattern can be assumed to be zero. Thus, each line of the electron beam inspection tool's raster scan can be assumed to be aligned with the edge of one of the array patterns. Figure 4 shows a time-domain signal of the nominal peak value at the edge of the array pattern over time.

[0039] A time-domain signal of the nominal peak value at the edge of the array pattern may be generated, and an FFT may be performed to obtain the nominal frequency in the frequency domain. Figure 5 shows the conversion of the time-domain signal to a frequency-domain signal. This technique may be performed for all rows of the array pattern within the nominal cell, and the resulting spectrum may be averaged to obtain the nominal frequency.

[0040] Edge detection may be performed to determine the actual edge locations of the pattern. In one embodiment, an actual swath image of the pattern on the workpiece may be used to detect the actual edges. An edge detection method may be performed to detect the edges. FIG. 6 illustrates vertical edge detection for a scan in the X direction, and FIG. 9 illustrates horizontal edge detection for a scan in the Y direction. In one embodiment, the image may be analyzed for alternating dark and light spots. The edges of the transitions from dark spots to light spots or from light spots to dark spots on the workpiece may be detected as the actual edges of the pattern. Subsequently, actual peaks of the scan lines of the raster scan of the inspection system may be determined based on the detected edges. These actual peaks may be aligned with some of the detected actual edges of the pattern on the workpiece.

[0041] Returning to Figure 1, at 103, the X-direction offset for the workpiece between the nominal cell size and the profile is determined. The peak deviation of the actual peak from the nominal peak of the array pattern can be determined. The edge deviation with respect to time can also be determined.

[0042] The peak deviation between the actual peak and the nominal peak of the array pattern can be determined, which may be generated as a time-domain signal, and an FFT may be performed on the time-domain signal to remove edge roughness to obtain the vibration frequency.

[0043] At 104, an X-direction vibration spectrum is determined based on the X-direction offset. This may involve generating a time-domain signal of the calculated peak deviation and performing an FFT on it. The resulting frequency spectrum may be averaged to calculate the vibration frequency. While the pattern is typically uniform across the workpiece, the vibration spectrum may affect this uniformity.

[0044] The inspection system can compare the vibration spectrum to specifications to determine if the inspection system is within tolerance or if adjustments to the inspection system are needed. Interactions with the stage, enclosure, or environment outside the inspection tool may need to be adjusted.

[0045] A similar approach to that of the X direction can be performed in the Y direction: edge detection can detect vertical edges for the X direction and horizontal edges for the Y direction to determine vertical and horizontal vibrations, respectively.

[0046] At 105, a Y-direction profile of the image is determined. The Y-direction profile includes the edges of the pattern across the Y direction. The Y direction is orthogonal to the X direction. In one example, the swath includes two or more rows in the array. For example, FIG. 6 shows four rows extending horizontally. At 106, a Y-direction offset is determined for the workpiece between the nominal cell size and the profile. At 107, a Y-direction vibration spectrum is determined based on the Y-direction offset.

[0047] In one example, the nominal line and the deviation of the actual edge points from this line can be determined after the horizontal edge points are determined, the FFT spectra are determined, and all spectra are averaged to thereby determine the vibration frequency.

[0048] The method 100 may include averaging the X-direction vibration spectrum and the Y-direction vibration spectrum and determining a vibration frequency for the inspection system from the averaging using a processor.

[0049] In another embodiment of method 100, a swath-mode raster scan of the electron beam inspection tool may be performed in the X direction. In this embodiment, edge detection as shown in FIG. 5 is performed on vertical edges. FIG. 7 shows the time domain signal of the peak deviation in the X direction. FIG. 8 shows the FFT spectrum of the peak deviation in the X direction. The average of the FFT spectrum gives the vertical vibration frequency of the electron beam inspection tool.

[0050] In another embodiment of method 100, a swath mode raster scan of the electron beam inspection tool may be performed in the Y direction. In this embodiment, edge detection is performed on horizontal edges, as shown in Figure 9. Figure 10 shows the time domain signal of the peak deviation in the Y direction. Figure 11 shows the FFT spectrum of the peak deviation in the Y direction. The average of the FFT spectrum gives the horizontal vibration frequency of the inspection tool.

[0051] In another embodiment, images are acquired on selected equally spaced markers on a workpiece, and embodiments disclosed herein can be used to measure their relative positions and extract frequency information.

[0052] In another embodiment, images are obtained over equally spaced alternating bright and dark regions. An external oscilloscope is used to intercept the raw detector signals and perform real-time analysis in the frequency domain.

[0053] Embodiments of method 100 improve the speed of detection of mechanical vibrations. The source of the vibration can be determined based on the spectrum. The frequency can be matched to an entry in a library or correlated with a resonant frequency corresponding to a stage, chamber, column, or other component.

[0054] Embodiments of method 100 can improve speed by up to 20 times over that of existing techniques. In one example, the speed of vibration frequency detection was 30 seconds, compared to 10 minutes for existing methods for vibration frequency detection. Furthermore, because the embodiments disclosed herein use images as input, these embodiments are more adaptable to various patterns. The embodiments disclosed herein also have improved accuracy because the FFT calculations and averaged spectra negate the effects of distortion in the input image. The embodiments disclosed herein can be used for runtime modeling when the underlying design on the workpiece is available.

[0055] Line edge roughness (LER) effects can be largely eliminated by averaging. In the X direction, the edge position is determined after averaging over the height of the swath image. In the Y direction, the result is determined after averaging over several pixels within one array pitch, which can be on the order of tens to hundreds of pixels.

[0056] Although disclosed with respect to vibration, method 100 can also be used for EMI. Both EMI and vibration appear as periodic variations in edge position in an image. A library that can be used for matching or correlation can include sources of EMI. For example, X-direction vibration spectrum and Y-direction vibration spectrum can refer to tool vibration and / or EMI, since vibration affecting an image can have various causes in an inspection system.

[0057] When adding swathing capabilities to an inspection system, the embodiments disclosed herein can be used as a diagnostic tool to measure the overall noise level of the inspection system during operation and provide information (e.g., frequency and amplitude) for troubleshooting. During normal inspection tool operation, the embodiments disclosed herein can be run periodically (e.g., online or offline) to check images for noise baselines and signatures and for monitoring the health of the inspection tool. For example, changes can be made to cooling water and / or air flow rates, adjustments to the isolation system and / or wafer stage, or sensor positions or gain parameters of EMI cancellation systems.

[0058] 12 is a block diagram of one embodiment of an inspection system 200. The inspection system 200 includes a workpiece inspection tool (including an electron column 201) configured to generate an image of a workpiece 204.

[0059] The inspection system includes an output acquisition subsystem that includes at least an energy source and a detector. The output acquisition subsystem can be an electron beam-based output acquisition subsystem. For example, in one embodiment, the energy directed at the workpiece 204 includes electrons, and the energy detected from the workpiece 204 includes electrons. Thus, the energy source can be an electron beam source. In one such embodiment shown in FIG. 12, the output acquisition subsystem includes an electron column 201 coupled to a computer subsystem 202. A stage 210 can hold the workpiece 204.

[0060] 12, electron column 201 includes an electron beam source 203 configured to generate electrons that are focused onto workpiece 204 by one or more elements 205. Electron beam source 203 may include, for example, a cathode source or an emitter tip. One or more elements 205 may include, for example, a gun lens, an anode, a beam limiting hole, a gate valve, a beam current selection hole, an objective lens, and a scanning subsystem, all of which may include any such suitable elements known in the art.

[0061] Electrons returning from workpiece 204 (e.g., secondary electrons) may be focused onto detector 207 by one or more elements 206. One or more elements 206 may include a scanning subsystem that may be the same as the scanning subsystem included in element 205, for example.

[0062] Electron column 201 may also include any other suitable elements known in the art.

[0063] 12 shows electron column 201 configured so that electrons are directed at workpiece 204 at an oblique angle of incidence and scattered from workpiece 204 at another oblique angle, the electron beam may be directed at workpiece 204 at any suitable angle and scattered from workpiece 204. Additionally, the electron beam-based output acquisition subsystem may be configured to use multiple modes (e.g., using different illumination angles, collection angles, etc.) to generate an image of workpiece 204. The multiple modes of the electron beam-based output acquisition subsystem may differ in any image generation parameter of the output acquisition subsystem.

[0064] The computer subsystem 202 may be coupled to the detector 207 as described above. The detector 207 may detect electrons returning from the surface of the workpiece 204, thereby forming an electron beam image of the workpiece 204. The electron beam image may include any suitable electron beam image. The computer subsystem 202 may be configured to perform any of the functions described herein using the output of the detector 207 and / or the electron beam image. The computer subsystem 202 may also be configured to perform any additional steps described herein. The system 200, including the output obtaining subsystem shown in FIG. 12, may be further configured as described herein.

[0065] It should be noted that FIG. 12 is provided herein to generally illustrate configurations of electron beam-based output acquisition subsystems that can be used in the embodiments described herein. The electron beam-based output acquisition subsystem configurations described herein may be modified to optimize the performance of the output acquisition subsystem, as is typically done when designing a commercially available output acquisition system. In addition, the systems described herein may be implemented using existing systems (e.g., by adding the functionality described herein to an existing system). For some such systems, the methods described herein may be provided as optional functions of the system (e.g., in addition to other functions of the system). Alternatively, the systems described herein may be designed as entirely new systems.

[0066] The system 200 may include other components such as a cooling system, an isolation system, a sensor, or a system for canceling EMI.

[0067] Although the output acquiring subsystem is described above as an electron beam-based output acquiring subsystem, the output acquiring subsystem may also be an ion beam-based output acquiring subsystem. Such an output acquiring subsystem may be configured as shown in FIG. 12 , except that the electron beam source may be replaced with any suitable ion beam source known in the art. Additionally, the output acquiring subsystem may be any other suitable ion beam-based output acquiring subsystem, such as those included in commercially available focused ion beam (FIB) systems, helium ion microscope (HIM) systems, and secondary ion mass spectrometry (SIMS) systems.

[0068] The computer subsystem 202 includes a processor 208 and an electronic data storage unit 209. The processor 208 may include a microprocessor, microcontroller, or other device.

[0069] Computer subsystem 202 may be coupled to the components of system 200 in any suitable manner (e.g., via one or more transmission media, which may include wired and / or wireless transmission media) such that processor 208 can receive the output. Processor 208 may be configured to perform several functions using the output. The inspection system may receive instructions or other information from processor 208. Processor 208 and / or electronic data storage unit 209 may optionally be in electronic communication with another inspection system, metrology system, or review system (not shown) to receive additional information or send instructions.

[0070] The processor 208 is in electronic communication with an inspection system, such as the detector 207. The processor 208 may be configured to process images generated using measurements from the detector 207. For example, the processor may perform an embodiment of method 100 or method 200.

[0071] The computer subsystem 202, other systems, or other subsystems described herein may be part of a variety of systems, including a personal computer system, an image computer, a mainframe computer system, a workstation, a network appliance, an internet appliance, or other devices. The subsystem or system may also include any suitable processor known in the art, such as a parallel processor. In addition, the subsystem or system may include a platform with high-speed processing and software, either as a standalone or networked tool.

[0072] The processor 208 and electronic data storage unit 209 may be located within or otherwise part of the system 200 or another device. In one example, the processor 208 and electronic data storage unit 209 may be part of a stand-alone control unit or may be in a centralized quality control unit. Multiple processors 208 or electronic data storage units 209 may be used.

[0073] The processor 208 may actually be implemented by any combination of hardware, software, and firmware. Also, its functions as described herein may be performed by one unit or divided among different components, each of which may be implemented by any combination of hardware, software, and firmware. Program code or instructions for the processor 208 to perform various methods and functions may be stored in a readable storage medium, such as memory in the electronic data storage unit 209 or other memory. The electronic data storage unit 209 or other memory may also include a library of tool vibration and EMI sources.

[0074] Where system 200 includes two or more computer subsystems 202, the different subsystems may be coupled to one another such that images, data, information, instructions, etc. may be passed between the subsystems. For example, one subsystem may be coupled to additional subsystems by any suitable transmission medium, which may include any suitable wired and / or wireless transmission medium known in the art. Two or more such subsystems may also be effectively coupled by a shared computer-readable storage medium (not shown).

[0075] Processor 208 may be configured to perform several functions using the output of system 200 or other outputs. For example, processor 208 may be configured to send the output to electronic data storage unit 209 or another storage medium. Processor 208 may be configured to perform some or all of the steps of method 100 or other embodiments disclosed herein. Processor 208 may be further configured as described herein.

[0076] Processor 208 may be communicatively coupled to any of the various components or subsystems of system 200 in any manner known in the art. Processor 208 may also be configured to receive and / or acquire data or information from other systems (e.g., inspection results from an inspection system, such as a review tool, a remote database containing design data, etc.) over a transmission medium, which may include wired and / or wireless portions. In this manner, the transmission medium may serve as a data link between processor 208 and other subsystems of system 200 or systems external to system 200.

[0077] An additional embodiment relates to a non-transitory computer-readable medium storing program instructions executable on a controller for performing computer-implemented method 100 as disclosed herein. In particular, as shown in Figure 12, an electronic data storage unit 209 or other storage medium may include a non-transitory computer-readable medium including program instructions executable on processor 208. The computer-implemented method may include any step of any of the methods described herein, including method 100.

[0078] The program instructions may be implemented in any of a variety of ways, including procedure-based techniques, component-based techniques, and / or object-oriented techniques, among others. For example, the program instructions may be implemented using ActiveX controls, C++ objects, JavaBeans, Microsoft Foundation Classes (MFC), Streaming SIMD Extensions (SSE), or other technologies or methods as desired.

[0079] The workpiece may be, for example, a semiconductor wafer or a reticle. As used herein, the term "wafer" generally refers to a substrate formed of a semiconductor or non-semiconductor material. Examples of such semiconductor or non-semiconductor materials include, but are not limited to, monocrystalline silicon, gallium nitride, gallium arsenide, indium phosphide, sapphire, and glass. Such substrates may be commonly found and / or processed in semiconductor manufacturing facilities.

[0080] A wafer may include one or more layers. For example, such layers may include, but are not limited to, photoresist, dielectric materials, conductive materials, and semiconductor materials. Many different types of such layers are known in the art, and the term "wafer" as used herein is intended to encompass wafers including all types of such layers.

[0081] One or more layers formed on a wafer may be patterned or unpatterned. For example, a wafer may include multiple dies, each having repeatable patterned features or periodic structures. The formation and processing of such material layers ultimately results in a completed device. Many different types of devices may be formed on a wafer, and the term "wafer," as used herein, is intended to encompass a wafer having any type of device fabricated thereon as known in the art.

[0082] Other types of wafers can also be used. For example, the wafers may be used to manufacture LEDs, solar cells, magnetic disks, flat panels, or polishing plates. Other workpieces can be used with the techniques and systems disclosed herein.

[0083] Although the present disclosure has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present disclosure may be made without departing from the scope of the present disclosure. Accordingly, the present disclosure is intended to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A particle beam source that generates a beam of particles, A stage configured to hold a workpiece within the path of the particle beam, A detector configured to receive the beam of particles reflected from the workpiece, A processor that communicates electronically with the aforementioned detector. The processor is equipped with, An image of the workpiece is received, and the image includes an array of patterns on the workpiece. The X-direction profile of the aforementioned image is determined, and the X-direction profile includes the edges of the pattern across the X-direction. Determine the X-direction offset for the workpiece between the nominal cell size and the profile, The vibration spectrum in the X direction is determined based on the aforementioned X-direction offset. A system characterized by being configured in such a way.

2. The system according to claim 1, wherein the particles are electrons.

3. A system according to claim 1, wherein the processor is further configured to cut the image into swaths of the pattern.

4. The system according to claim 3, wherein the swath in the image includes two or more columns in the array.

5. The system according to claim 1, wherein the processor is The Y-direction profile of the aforementioned image is determined, and the Y-direction profile includes the edges of the pattern across the Y-direction, and the Y-direction is orthogonal to the X-direction. Determine the Y-direction offset for the workpiece between the nominal line and the Y-direction profile. The vibration spectrum in the Y direction is determined based on the aforementioned Y-direction offset. A system characterized by being further configured in such a way.

6. The system according to claim 5, wherein the swath in the image includes two or more rows in the array.

7. The system according to claim 5, wherein the processor is further configured to average the vibration spectrum in the X direction and the vibration spectrum in the Y direction.

8. A system according to claim 7, wherein the processor is further configured to determine the vibration frequency for the system from the averaging.

9. The system according to claim 1, wherein the workpiece is a semiconductor wafer or a reticle.

10. A step of receiving an image of a workpiece generated by an inspection system into a processor, wherein the image includes an array of patterns on the workpiece; A step of determining the X-direction profile of the image using the processor, wherein the X-direction profile includes the edges of the pattern over the X-direction; A step of using the processor to determine the X-direction offset for the workpiece between the nominal cell size and the profile, The steps include: using the processor to determine the vibration spectrum in the X direction based on the X-direction offset; A method characterized by including the following.

11. A method according to claim 10, further comprising the step of generating the image using the inspection system.

12. A method according to claim 10, characterized in that the inspection system is a scanning electron microscope.

13. A method according to claim 10, further comprising the step of using the processor to cut the image into a swath of the pattern.

14. A method according to claim 13, characterized in that the swath in the image includes two or more columns in the array.

15. A method according to claim 10, comprising the steps of determining a Y-direction profile of the image using the processor, wherein the Y-direction profile includes the edges of the pattern over the Y-direction, and the Y-direction is orthogonal to the X-direction, A step of determining the Y-direction offset for the workpiece between the nominal line and the Y-direction profile using the processor, The steps include: using the processor to determine the vibration spectrum in the Y direction based on the Y-direction offset; A method characterized by further comprising:

16. A method according to claim 15, characterized in that the swath in the image includes two or more rows in the array.

17. A method according to claim 15, further comprising the steps of: averaging the vibration spectrum in the X direction and the vibration spectrum in the Y direction; and determining the vibration frequency for the inspection system from the average using the processor.

18. A method according to claim 10, characterized in that the workpiece is a semiconductor wafer or a reticle.

19. A non-temporary computer-readable medium characterized by storing a program configured to instruct a processor to perform the method described in claim 10.

20. A non-temporary computer-readable medium characterized by storing a program configured to instruct a processor to perform the method described in claim 15.

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