System and method for image disturbance compensation

Abstract

Systems, apparatus, and methods include generating a reference signal based on a power input of an imaging system; generating a scan signal indicative of a scan of the sample; extracting first disturbance data and second disturbance data from an image generated according to the scan; generating a calibration frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scan signal; combining the calibration frequency, amplitude, and phase of the image perturbation with a reference signal to generate a compensation signal; and control a plurality of deflection drivers using the compensation signal, the plurality of deflection drivers being used to manipulate charged particles to scan the sample.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application 63 / 408,772, filed on September 21, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The description herein relates to the field of inspection systems and, more particularly, to systems for image perturbation compensation. Background Art

[0004] During the manufacturing process of integrated circuits (ICs), unfinished or completed circuit components are inspected to ensure that they are manufactured according to the design and are free of defects. Inspection systems that utilize optical microscopes typically have a resolution as low as a few hundred nanometers; and the resolution is limited by the wavelength of light. As the physical size of IC components continues to decrease to below 100 nanometers and even below 10 nanometers, inspection systems with higher resolution than those utilizing optical microscopes are needed.

[0005] Charged particle (e.g., electron) beam microscopes, such as scanning electron microscopes (SEMs) or transmission electron microscopes (TEMs), capable of reducing resolution to less than a nanometer, can be used as practical tools for inspecting IC components having feature sizes less than 100 nanometers. Using an SEM, electrons from a single primary electron beam or electrons from multiple primary electron beams can be focused on locations of interest on the wafer being inspected. The primary electrons interact with the wafer and can be backscattered or can cause the wafer to emit secondary electrons. The intensity of the electron beam, including the backscattered electrons and the secondary electrons, can vary based on the properties of the internal and external structures of the wafer, and can therefore indicate whether the wafer is defective. Summary of the invention

[0006] Embodiments of the present disclosure provide apparatus, systems and methods for image perturbation compensation. In some embodiments, the system and method may include generating a reference signal based on a power input of an imaging system; generating a scanning signal indicating a scan of a sample; extracting first perturbation data and second perturbation data from an image generated according to the scan; using the extracted first perturbation data and second perturbation data, the reference signal and the scanning signal to generate a calibration frequency, amplitude and phase of the image perturbation; combining the calibration frequency, amplitude and phase of the image perturbation with the reference signal to generate a compensation signal; and using the compensation signal to control a plurality of deflection drives, which are used to manipulate charged particles to scan the sample.

[0007] In some embodiments, systems and methods may include generating a reference signal based on a power input to an imaging system; generating a scanning signal indicative of a scan of a sample; extracting a frequency curve of an image perturbation from an image generated based on the scan; generating a calibration signal based on the reference signal and the extracted frequency distribution; generating a compensation signal using the calibration signal and the reference signal; transforming image coordinates associated with the compensation signal into deflection drive coordinates; and using the deflection drive coordinates of the compensation signal to control a plurality of deflection drives used to manipulate charged particles to scan the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0009] Figure 2A is a schematic diagram illustrating an exemplary multi-beam system consistent with an embodiment of the present disclosure, which is Figure 1 Portions of an exemplary charged particle beam inspection system.

[0010] Figure 2B is a schematic diagram illustrating an exemplary single beam system consistent with an embodiment of the present disclosure, which is Figure 1 Portions of an exemplary charged particle beam inspection system.

[0011] Figure 3A is a plan view of an illustrative embodiment of a deflection structure implemented in an electron beam inspection system consistent with embodiments of the present disclosure.

[0012] Figure 3B is a cross-sectional view of an illustrative embodiment of a deflection system that may be used in an electron beam inspection system consistent with embodiments of the present disclosure.

[0013] Figure 4A is a pictorial representation of a driver consistent with an embodiment of the present disclosure.

[0014] Figure 4B is a pictorial representation of a number of drivers consistent with embodiments of the present disclosure.

[0015] Figure 5 is a schematic diagram of an exemplary system for image disturbance compensation consistent with embodiments of the present disclosure.

[0016] Fig. 6A and Figure 6B are exemplary generated images of line patterns on a sample consistent with embodiments of the present disclosure.

[0017] Figure 7 is a flow chart illustrating an exemplary process of image perturbation compensation consistent with embodiments of the present disclosure. DETAILED DESCRIPTION

[0018] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments set forth in the following description of exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of apparatus and methods consistent with various aspects related to the present subject matter as described in the appended claims. For example, although some embodiments are described in the context of utilizing electron beams, the present disclosure is not limited thereto. Other types of charged particle beams may be similarly applied. In addition, other imaging systems may also be used, such as optical imaging, photoelectric detection, X-ray detection, extreme ultraviolet inspection, deep ultraviolet inspection, etc., which generate images of corresponding types in these systems.

[0019] Electronic devices are made up of circuits formed on a silicon wafer called a substrate. Many circuits can be formed together on the same silicon wafer and are called an integrated circuit, or IC. The size of these circuits has been greatly reduced so that more circuits can be accommodated on a substrate. For example, an IC chip in a smartphone can be as small as a thumbnail, but can include more than 2 billion transistors, each less than one thousandth the size of a human hair.

[0020] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process that typically involves hundreds of individual steps. An error in even one step can result in a defect in the finished IC, rendering it useless. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs made in the process; that is, to increase the overall yield of the process.

[0021] One element of improving yield is monitoring the chip manufacturing process to ensure that a sufficient number of functional ICs are produced. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection can be performed using a scanning electron microscope (SEM). The SEM can be used to image these extremely small structures, in effect taking a "photograph" of the wafer structure. The image can be used to determine whether the structure was formed correctly and whether the structure was formed in the correct location. If the structure is defective, the process can be adjusted so that the defect is less likely to occur again. Defects can be generated during various stages of semiconductor processing. For the reasons mentioned above, it is very important to detect defects early, accurately and efficiently.

[0022] The working principle of SEM is similar to that of a camera. A camera takes pictures by receiving and recording the brightness and color of light reflected or emitted from a person or object. SEM takes "pictures" by receiving and recording the energy or number of electrons reflected or emitted from a structure. Before taking such a "picture", an electron beam can be provided to the structure, and when the electrons are reflected or emitted ("leave") from the structure, the detector of the SEM can receive and record the energy or number of these electrons to generate an image. In order to take such a "picture", some SEMs use a single electron beam (referred to as a "single-beam SEM"), while some SEMs use multiple electron beams (referred to as a "multi-beam SEM") to take multiple "pictures" of the wafer. By using multiple electron beams, the SEM can provide more electron beams to the structure for obtaining these multiple "pictures", resulting in more electrons leaving the structure. Therefore, the detector can receive more leaving electrons at the same time and generate images of the wafer structure with higher efficiency and faster speed.

[0023] Image disturbances induced by system power lines are one of the main key sources of image disturbances in inspection systems. Specifically, periodic electromagnetic disturbances (e.g., disturbances to images with periodic patterns) from system power lines are key sources of image disturbances. These power line-induced image disturbances may be caused by any electrical module, cable, rack through signal, ground, electromagnetic field in space, etc., and should be compensated to generate accurate images (e.g., during inspection).

[0024] However, conventional inspection systems are constrained. Conventional inspection systems can use pure software-based methods to compensate for image disturbances. However, pure software-based compensation methods are unreliable and inadequate because they can only recognize or characterize some image disturbance patterns, but cannot recognize or characterize other image disturbance patterns (e.g., they cannot compensate for image disturbances of dots, holes, etc.).

[0025] Some of the disclosed embodiments provide systems and methods that address some or all of these disadvantages by using a hardware-based approach to compensate for image disturbances. The disclosed embodiments may include extracting the magnitude and phase of image disturbances from an image, generating a compensation signal, and providing the compensation signal to a deflection driver to compensate for image disturbances of any type of pattern induced by a power line.

[0026] For the sake of clarity, the relative sizes of the components in the figures may be exaggerated. In the following description of the drawings, identical or similar reference numerals refer to identical or similar components or entities, and only the differences with respect to individual embodiments are described.

[0027] As used herein, unless expressly stated otherwise, the term "or" encompasses all possible combinations unless not feasible. For example, if a component is stated to include A or B, then, unless expressly stated otherwise or not feasible, the component may include A, or B, or A and B. As a second example, if a component is stated to include A, B, or C, then, unless expressly stated otherwise or not feasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0028] Without limiting the scope of the present disclosure, some embodiments may be described in the context of providing detectors and detection methods in systems utilizing electron beams. However, the present disclosure is not limited thereto. Other types of charged particle beams may be similarly applied. In addition, the systems and methods for detection may be used in other imaging systems, such as optical imaging, photon detection, X-ray detection, ion detection, etc.

[0029] Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure is illustrated. The EBI system 100 can be used for imaging. Figure 1 As shown in , the EBI system 100 includes a main chamber 101, a load / lock chamber 102, an electron beam tool 104, and an equipment front end module (EFEM) 106. The electron beam tool 104 is located in the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include additional loading ports. The first loading port 106a and the second loading port 106b receive a front-opening wafer transport box (FOUP), which contains wafers to be inspected (e.g., semiconductor wafers or wafers made of other materials) or samples (wafers and samples can be used interchangeably). "Batch" refers to a plurality of wafers that can be loaded for processing as a batch.

[0030] One or more robots (not shown) in the EFEM 106 can transfer the wafer to the load / lock chamber 102. The load / lock chamber 102 is connected to a load / lock vacuum pump system (not shown), which removes gas molecules in the load / lock chamber 102 to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robots (not shown) can transfer the wafer from the load / lock chamber 102 to the main chamber 101. The main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules in the main chamber 101 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer will be inspected by the electron beam tool 104. The electron beam tool 104 can be a single beam system or a multi-beam system.

[0031] The controller 109 is electrically connected to the electron beam tool 104. The controller 109 may be a computer configured to perform various controls of the EBI system 100. Figure 1 The controller 109 is shown as being external to the structure including the main chamber 101 , the load / lock chamber 102 , and the EFEM 106 , but it should be understood that the controller 109 may be part of the structure.

[0032] In some embodiments, the controller 109 may include one or more processors (not shown). The processor may be a general or special electronic device capable of manipulating or processing information. For example, the processor may include any number of central processing units (or "CPUs"), graphics processing units (or "GPUs"), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general array logic (GALs), complex programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), systems on chip (SoCs), application specific integrated circuits (ASICs), and any combination of any type of circuit capable of data processing. The processor may also be a virtual processor, which includes one or more processors distributed across multiple machines or devices coupled via a network.

[0033] In some embodiments, the controller 109 may also include one or more memories (not shown). The memory may be a general or special electronic device capable of storing code and data accessible by a processor (e.g., via a bus). For example, the memory may include any number of random access memories (RAM), read-only memories (ROM), optical disks, magnetic disks, hard disk drives, solid-state drives, flash drives, secure digital (SD) cards, memory sticks, compact flash (CF) cards, or any combination of any type of storage device. The code may include an operating system (OS) and one or more applications (or "apps") for a specific task. The memory may also be a virtual memory, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0034] Embodiments of the present disclosure may provide a single charged particle beam imaging system ("single beam system"). Compared to a single beam system, a multi-charged particle beam imaging system ("multi-beam system") may be designed to optimize the throughput of different scanning modes. Embodiments of the present disclosure provide a multi-beam system that is capable of optimizing the throughput of different scanning modes by using beam arrays with different geometries and adapting to different throughput and resolution requirements.

[0035] Now to Figure 2AReference is made to a schematic diagram illustrating an exemplary electron beam tool 104 including a multi-beam inspection tool consistent with an embodiment of the present disclosure. Figure 1 In some embodiments, the electron beam tool 104 can be operated as a single beam inspection tool, wherein the single beam inspection tool is Figure 1 The multi-beam electron beam tool 104 (also referred to herein as the apparatus 104) includes an electron source 201, a Coulomb aperture plate (or "gun aperture plate") 271, a converging lens 210, a source conversion unit 220, a primary projection system 230, a motorized stage 209, and a sample holder 207 supported by the motorized stage 209, the sample holder 207 being used to hold a sample 208 to be inspected (e.g., a wafer or a photomask). The multi-beam electron beam tool 104 may also include a secondary projection system 250 and an electronic detection device 240. The primary projection system 230 may include an objective lens 231. The electronic detection device 240 may include a plurality of detection elements 241, 242, and 243. A beam splitter 233 and a deflection scanning unit 232 may be positioned inside the primary projection system 230.

[0036] The electron source 201, the Coulomb aperture plate 271, the converging lens 210, the source conversion unit 220, the beam splitter 233, the deflection scanning unit 232 and the primary projection system 230 can be aligned with the main optical axis 204 of the device 104. The secondary projection system 250 and the electron detection device 240 can be aligned with the secondary optical axis 251 of the device 104.

[0037] The electron source 201 may include a cathode (not shown) and an extractor or an anode (not shown), wherein during operation, the electron source 201 is configured to emit primary electrons from the cathode, and the primary electrons are extracted or accelerated by the extractor and / or the anode to form a primary electron beam 202, which forms a primary beam cross (virtual or real) 203. The primary electron beam 202 can be visualized as being emitted from the primary beam cross 203.

[0038] The source conversion unit 220 may include an image forming element array (not shown), an aberration compensator array (not shown), a beam limiting aperture array (not shown), and a pre-bent micro-deflector array (not shown). In some embodiments, the pre-bent micro-deflector array deflects the multiple primary sub-beams 211, 212, 213 of the primary electron beam 202 to vertically enter the beam limiting aperture array, the image forming element array, and the aberration compensator array. In some embodiments, the device 104 can be operated as a single beam system to generate a single primary sub-beam. In some embodiments, the converging lens 210 is designed to focus the primary electron beam 202 into a parallel beam and is vertically incident on the source conversion unit 220. The image forming element array may include a plurality of micro-deflectors or micro-lenses to affect the multiple primary sub-beams 211, 212, 213 of the primary electron beam 202 and form a plurality of parallel images (virtual or real) of the primary beam cross 203, each of the primary sub-beams 211, 212, and 213 having one parallel image. In some embodiments, the aberration compensator array may include a field curvature compensator array (not shown) and an astigmatism compensator array (not shown). The field curvature compensator array may include a plurality of micro lenses to compensate for the field curvature aberration of the primary beamlets 211, 212, and 213. The astigmatism compensator array may include a plurality of micro astigmatists to compensate for the astigmatism aberration of the primary beamlets 211, 212, and 213. The beam limiting aperture array may be configured to limit the diameters of the individual primary beamlets 211, 212, and 213. Figure 2A Three primary sub-beams 211, 212, and 213 are shown as an example, and it should be understood that the source conversion unit 220 can be configured to form any number of primary sub-beams. The controller 109 can be connected to Figure 1 Controller 109 may be used to control various parts of the EBI system 100, such as source conversion unit 220, electronic detection device 240, primary projection system 230, or motorized stage 209. In some embodiments, as explained in further detail below, controller 109 may perform various image and signal processing functions. Controller 109 may also generate various control signals to govern the operation of the charged particle beam inspection system.

[0039] The converging lens 210 is configured to focus the primary electron beam 202. The converging lens 210 may also be configured to adjust the current of the primary sub-beams 211, 212, and 213 downstream of the source conversion unit 220 by changing the optical power of the converging lens 210. Alternatively, the current may be varied by changing the radial size of the beam limiting apertures within the beam limiting aperture array corresponding to the individual primary sub-beams. The current may be varied by changing both the radial size of the beam limiting apertures and the optical power of the converging lens 210. The converging lens 210 may be an adjustable converging lens, which may be configured so that the position of its first principal plane is movable. The adjustable converging lens may be configured magnetically, which may cause the off-axis sub-beams 212 and the off-axis sub-beams 213 to irradiate the source conversion unit 220 at a rotation angle. The rotation angle varies with the optical power of the adjustable converging lens or the position of the first principal plane. The converging lens 210 may be an anti-rotation converging lens, which may be configured to keep the rotation angle unchanged when the optical power of the converging lens 210 is changed. In some embodiments, the converging lens 210 may be an adjustable anti-rotation converging lens, in which the rotation angle does not change when its optical power and the position of its first principal plane are changed.

[0040] The objective lens 231 can be configured to focus the sub-beams 211, 212, and 213 onto the sample 208 for inspection, and in the current embodiment, three detection spots 221, 222, and 223 can be formed on the surface of the sample 208. The Coulomb aperture plate 271 is configured to block peripheral electrons of the primary electron beam 202 in operation to reduce the Coulomb effect. The Coulomb effect can expand the size of each of the detection spots 221, 222, and 223 of the primary sub-beams 211, 212, 213, and thus reduce the inspection resolution.

[0041] The beam splitter 233 may be, for example, a Wien filter including an electrostatic deflector ( Figure 2A 213). In operation, the beam splitter 233 can be configured to apply an electrostatic force to individual electrons of the primary sub-beams 211, 212, and 213 via an electrostatic dipole field. The electrostatic force is equal in magnitude to the magnetic force applied to the individual electrons by the magnetic dipole field of the beam splitter 233, but opposite in direction. Thus, the primary sub-beams 211, 212, and 213 can pass at least substantially straight through the beam splitter 233, with a deflection angle that is at least substantially zero.

[0042] The deflection scanning unit 232 is configured in operation to deflect the primary beamlets 211, 212 and 213 to scan the detection spots 221, 222 and 223 across the individual scanning areas in the section of the surface of the sample 208. In response to the primary beamlets 211, 212 and 213 or the detection spots 221, 222 and 223 being incident on the sample 208, electrons emerge from the sample 208 and generate three secondary electron beams 261, 262 and 263. Each of the secondary electron beams 261, 262 and 263 typically includes secondary electrons (having an electron energy ≤ 50 eV) and backscattered electrons (having an electron energy between 50 eV and the landing energy of the primary beamlets 211, 212 and 213). The beam splitter 233 is configured to deflect the secondary electron beams 261, 262 and 263 toward the secondary projection system 250. The secondary projection system 250 then focuses the secondary electron beams 261, 262, and 263 onto the detection elements 241, 242, and 243 of the electron detection device 240. The detection elements 241, 242, and 243 are arranged to detect the corresponding secondary electron beams 261, 262, and 263 and generate corresponding signals, which are sent to the controller 109 or a signal processing system (not shown), for example, to form an image of the corresponding scan area of ​​the sample 208.

[0043] In some embodiments, the detection elements 241, 242, and 243 detect the corresponding secondary electron beams 261, 262, and 263, respectively, and generate corresponding intensity signal outputs (not shown) to an image processing system (e.g., controller 109). In some embodiments, each detection element 241, 242, and 243 may include one or more pixels. The intensity signal output of a detection element may be the sum of the signals generated by all pixels within the detection element.

[0044] In some embodiments, the controller 109 may include an image processing system, which includes an image acquirer (not shown), a storage device (not shown). The image acquirer may include one or more processors. For example, the image acquirer may include a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquirer may be communicatively coupled to the electronic detection device 240 of the device 104 through a medium (such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, etc., or a combination thereof). In some embodiments, the image acquirer may receive a signal from the electronic detection device 240 and may form an image. Thus, the image acquirer may acquire an image of the sample 208. The image acquirer may also perform various post-processing functions, such as generating a contour, superimposing an indicator on the acquired image, etc. The image acquirer may be configured to perform adjustments such as brightness and contrast on the acquired image. In some embodiments, the storage device may be a storage medium such as a hard disk, a flash drive, a cloud storage, a random access memory (RAM), other types of computer-readable memory, etc. The storage device may be coupled to the image acquirer and may be used to save the scanned raw image data as an initial image and a post-processed image.

[0045] In some embodiments, the image acquirer can acquire one or more images of the sample based on the imaging signal received from the electronic detection device 240. The imaging signal can correspond to a scanning operation for implementing charged particle imaging. The acquired image can be a single image including multiple imaging areas. The single image can be stored in a storage device. The single image can be an initial image that can be divided into multiple areas. Each of the areas can include an imaging area that contains features of the sample 208. The acquired image can include multiple images of a single imaging area of ​​the sample 208 sampled multiple times in a time series. Multiple images can be stored in a storage device. In some embodiments, the controller 109 can be configured to perform an image processing step using multiple images of the same position of the sample 208.

[0046] In some embodiments, the controller 109 may include a measurement circuit device (e.g., an analog-to-digital converter) to obtain the distribution of the detected secondary electrons. The electron distribution data collected during the detection time window is combined with the corresponding scan path data of each of the primary sub-beams 211, 212, and 213 incident on the wafer surface, and can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208, and therefore can be used to reveal any defects that may be present in the wafer.

[0047] In some embodiments, the controller 109 may control the motorized stage 209 to move the sample 208 during the inspection of the sample 208. In some embodiments, the controller 109 may enable the motorized stage 209 to continuously move the sample 208 in one direction at a constant speed. In other embodiments, the controller 109 may enable the motorized stage 209 to change the movement speed of the sample 208 over time depending on the steps of the scanning process.

[0048] although Figure 2A The apparatus 104 is shown using three primary electron beams, but it should be understood that the apparatus 104 can use one, two, or more primary electron beams. The present disclosure does not limit the number of primary electron beams used in the apparatus 104. In some embodiments, the apparatus 104 can be a SEM used for lithography. In some embodiments, the electron beam tool 104 can be a single beam system or a multi-beam system.

[0049] For example, Figure 2B As shown in , consistent with embodiments of the present disclosure, an electron beam tool 100B (also referred to herein as apparatus 100B) can be a single beam inspection tool used in an EBI system 10. Apparatus 100B includes a wafer holder 136 supported by a motorized stage 134 to fix a wafer 150 to be inspected. Electron beam tool 100B includes an electron emitter, which may include a cathode 103, an anode 121, and a gun hole 122. Electron beam tool 100B also includes a beam limiting aperture 125, a converging lens 126, a column aperture 135, an objective lens assembly 132, and a detector 144. In some embodiments, objective lens assembly 132 can be a modified SORIL lens, which includes a pole piece 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. During imaging, the electron beam 161 emitted from the tip of the cathode 103 may be accelerated by the anode 121 voltage, pass through the gun bore 122, the beam limiting aperture 125, the converging lens 126, and be focused by the modified SORIL lens into a detection spot 170, and impinge on the surface of the wafer 150. A detector (such as the deflector 132c or other deflectors in the SORIL lens) may scan the detection spot 170 across the surface of the wafer 150. The detector 144 may collect secondary or scattered primary particles (e.g., secondary electrons or scattered primary electrons) emitted from the wafer surface to determine the intensity of the beam so that an image of a region of interest on the wafer 150 may be reconstructed.

[0050] An image processing system 199 may also be provided, which includes an image acquisition device 120, a storage device 130, and a controller 109. The image acquisition device 120 may include one or more processors. For example, the image acquisition device 120 may include a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquisition device 120 may be connected to the detector 144 of the electron beam tool 100B through a medium such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, or a combination thereof. The image acquisition device 120 may receive a signal from the detector 144 and may form an image. Thus, the image acquisition device 120 may acquire an image of the wafer 150. The image acquisition device 120 may also perform various post-processing functions, such as generating a contour, superimposing an indicator on the acquired image, etc. The image acquisition device 120 may be configured to perform adjustments to the brightness and contrast of the acquired image, etc. The storage device 130 may be a storage medium such as a hard disk, a random access memory (RAM), a cloud storage, other types of computer-readable memory, etc. The storage device 130 may be coupled to the image acquirer 120 and may be used to save the scanned raw image data as an initial image and a post-processed image. The image acquirer 120 and the storage device 130 may be connected to the controller 109. In some embodiments, the image acquirer 120, the storage device 130 and the controller 109 may be integrated together as an electronic control unit.

[0051] In some embodiments, the image acquirer 120 may acquire one or more images of the sample based on the imaging signal received from the detector 144. The imaging signal may correspond to a scanning operation for implementing charged particle imaging. The acquired image may be a single image including a plurality of imaging regions, which may include various features of the wafer 150. The single image may be stored in the storage device 130. Imaging may be performed based on imaging frames.

[0052] The condenser and illumination optics of an electron beam tool may include or be supplemented by an electromagnetic quadrupole electron lens. Figure 2B As shown in FIG. 1 , the electron beam tool 100B may include a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lenses are used to control the electron beam. For example, the first quadrupole lens 148 may be controlled to adjust the beam current, and the second quadrupole lens 158 may be controlled to adjust the beam spot size and beam shape.

[0053] Figure 2BThe inspection system is shown to use a charged particle beam device in which a single primary beam can be configured to generate secondary electrons by interacting with the wafer 150. The detector 144 can be placed along the optical axis 105, such as Figure 2B The primary electron beam may be configured to travel along the optical axis 105. Thus, the detector 144 may include a hole at its center so that the primary electron beam may pass through to reach the wafer 150.

[0054] Now to Figure 3A Reference is made to an embodiment of the present disclosure consistent with an electron beam inspection system (eg, Figure 1 The deflection structure 300 (e.g., Figure 2A The deflection scanning unit 232, Figure 2B FIG. 4 is a plan view of an illustrative embodiment of a deflector 132 c of FIG. 4 . The electron beam inspection system may include a single beam or a multi-beam system. In some embodiments, the deflection structure 400 may be one of several deflection structures implemented in a scanning deflection system of the electron beam inspection system. The deflection structure 400 may be used to steer the electron beam.

[0055] The deflection system may include a deflection structure and a driver system. The deflection structure may include a multi-pole structure. Figure 3A As shown in, the deflection structure 300 includes a multipole structure 310, a first driver system 301y and a second driver system 302x. The multipole structure 310 includes a first opposite electrode set 311A-B and a second opposite electrode set 312A-B, which can be configured to deflect the electron beam in each deflection direction (such as the x direction or the y direction) based on the output state applied to each set. The output state can correspond to the voltage applied to the electrode. The multipole structure 310 including the electrode set 311A-B and the electrode set 312A-B can be used as a dynamic deflector based on the voltage applied to the electrodes 311A-B and 312A-B. For example, when the first driver system 301y applies 0V to the electrode 311A ​​and the electrode 311B, and the second driver system 302x applies V1 to the electrode 312A and applies -V1 to the electrode 312B, the electron beam is deflected in the x direction. For another example, when the first driver system 301y applies V2 to electrode 311A ​​and -V2 to electrode 311B, and the second driver system 302x applies 0V to electrodes 312A and 312B, the electron beam is deflected in the y direction. When V1 and V2 increase, the deflection angle of the electron beam also increases. Figure 3A Four electrodes configured in the multipolar structure 310 are shown as an example, and it should be understood that the multipolar structure 310 can be configured to form more than four electrodes. Figure 3ATwo opposing electrode sets 311A-B and 312A-B configured in the multipolar structure 310 are shown as an example, and it should be understood that the multipolar structure 310 can be configured to form any number of opposing electrode sets (including one).

[0056] In some embodiments, electrode sets 311A-B and 312A-B may be formed in a substrate and include multiple beam manipulators in the substrate. For example, each beam manipulator may be electrically isolated from the other beam manipulators by a circular groove filled with an isolation material (e.g., such as a CVD oxide). Within the circular region, the manipulator may be formed, for example, by etching any isolation grooves between the deflection holes and the electrodes and by sputtering a metal layer over the locations where the electrodes should be formed. The metal layers may form electrode sets 311A-B and 312A-B, and some of the layers may be used for a first electrode set, while other layers may be used for a second electrode set.

[0057] The first driver system 301y is electrically connected to the first opposite electrode set 311A-B and is configured to provide multiple discrete output states to the first opposite electrode set 311A-B, and the second driver system 302x is electrically connected to the second opposite electrode set 312A-B and is configured to provide multiple discrete output states to the second opposite electrode set 312A-B. As discussed above with respect to the multi-pole structure 310, each of the driver systems 301y and 302x is configured to enable the corresponding opposite electrode set to deflect the electron beam in one direction by providing multiple discrete output states to the opposite electrode set (such as 311A-B and 312A-B). Each of the driver systems 301y and 302x can include multiple power supplies and multiple switches. A switch can refer to an active device that operates in a switch mode.

[0058] The power supply can be configured to provide multiple discrete output states. Alternatively, each of the multiple power supplies can be configured to provide discrete output states. For example, the driver 301y can be configured with a power supply that provides -100V, 0V, and +100V. As a further example, the driver 301y can be configured with a power supply that provides -100V, -50V, 0V, +50V, and +100V.

[0059] The plurality of switches may be configured by a controller and transmit an incoming discrete output state from a power supply to a corresponding set of opposite electrodes. Figure 1The controller 109 in the embodiment of the present invention can transmit a digital signal to apply the digital signal to turn on or off the switch to transmit the incoming discrete output state or block the output state. For example, three switches can connect three tap points associated with the power supply and the first opposite electrode set, and the controller can transmit a digital signal to select one of the three switches to transmit the desired output state from the power supply corresponding to the selected switch. The multiple switches can be MOS drivers that enable fast switching of the output state.

[0060] Now to Figure 4A Reference is made to a diagrammatic representation of a driver (such as driver system 301y) consistent with an embodiment of the present disclosure. Driver system 301y can be configured to provide multiple output states. The output states can correspond to, for example, -100V, 0V, and 100V. Driver system 301y can include a multi-output driver 340. The multi-output driver 340 can have a first output 341, a second output 342, and a third output 343. The outputs 341, 342, 343 can correspond to -100V, 0V, and 100V, respectively. Driver system 301y can also include a switching unit 350. The switching unit 350 can include a plurality of separate switches. The switching unit 350 can be configured to operate so that only one connection is allowed at a time. The switching unit 350 includes a first switch 351, a second switch 352, and a third switch 353. In Figure 4A In the state shown in , only the third switch 353 is connected. Therefore, the output to the electrode 311A ​​may be the output provided by the third output 343.

[0061] Control signals may be provided to components of the driver system 301y. Figure 4A As shown in , the controller 50 may be configured to control the driver system 301y. The controller 50 may be connected to the multi-output driver 340 and may be configured to instruct the multi-output driver 340 to operate. The controller 50 may be connected to the switch unit 350 and may be configured to instruct the switch unit 350 to operate. For example, the controller 50 may instruct the multi-output driver 340 to supply power and instruct the switch unit 350 to select one of the switches 351, 352, 353 to be connected so that an output state is provided to the electrode 311A.

[0062] In some embodiments, each of the first driver system 301y and the second driver system 302x may include multiple physical drivers. Each of the multiple physical drivers may include a power supply that provides a discrete output and a switch similar to that described above. The physical driver may be configured to provide a discrete output state to a corresponding electrode (such as electrodes 311A-B and 312A-B).

[0063] Now to Figure 4BReference is made to , which shows a graphical representation of multiple drivers consistent with an embodiment of the present disclosure. The driver system 301y can be configured to provide multiple output states by providing separate drivers that each produce an output. Each separate driver can be configured to provide its own output. The driver system 301y may include a first driver 361, a second driver 362, and a third driver 363. Each of the drivers 361, 362, and 363 can be configured to be powered at a predetermined output. The drivers 361, 362, and 363 are connected to switches 351, 352, and 353, respectively. The controller 50 can be configured to operate the switches 351, 352, and 353 separately. The controller 50 can be configured to operate the drivers 361, 362, and 363 separately. The controller 50 can be configured to operate the switches so that only one switch is connected at a time. In Figure 4B In the state shown in , only the third switch 353 is connected. Therefore, the output to the electrode 311A ​​can be provided by the third driver 363 only.

[0064] Now to Figure 3B Reference is made to a cross-sectional view of an illustrative embodiment of a deflection system 350 that can be used in an electron beam inspection system consistent with embodiments of the present disclosure. The deflection system 350 includes deflection structures 350A-D, each of which is located in a corresponding layer. Each deflection structure 350A-D includes a manipulator or multipole structure (310A-D) and a plurality of driver systems (301yA-D and 302xA-D). In some embodiments, the plurality of driver systems (301yA-D and 302xA-D) and the multipole structures (310A-D) can be implemented in separate layers. The deflection structures 350A-D can be used as Figure 2A The deflection scanning unit 232 or Figure 2B The deflector 132c of the deflector 132c is implemented in the embodiment of the present invention. Each of the plurality of driver systems (301yA-D and 302xA-D) is electrically connected to an opposite electrode set implemented in the multipole structure (310A-D) and is configured to provide a plurality of discrete output states to the opposite electrode set implemented in the multipole structure. For example, the driver 301yA can be electrically connected to an opposite electrode set implemented in the multipole structure 310A, while the driver 302xA can be electrically connected to another opposite electrode set in the multipole structure 310A. The deflection structures 350A-D and the deflection structure 300 (such as Figure 3A ) have the same functionality, such as steering an electron beam. The multipole structures 310A-D and the multipole structure 310 (as depicted in Figure 3A ) share the same functionality to deflect the electron beam in one direction when provided with an output state from the driver system. Driver systems 301A-D and 302A-D and driver systems 301y and 302x (as shown in Figure 3A) share the same functionality, providing discrete output states for the multipole structure to deflect the beam. Figure 3B A four-layer deflection structure 350A-D is shown, but it should be appreciated that the deflection structure may be implemented with any number of layers.

[0065] Although in Figure 3B In an embodiment, the size of each layer in the multiple layers (e.g., 310A-D) is determined to have substantially the same size, but the size of each layer can be determined by the physical size (such as length, inner diameter, and outer diameter) of the electrodes implemented in each layer and corresponds to the deflection angle. For example, when the driver systems 301yA-D and 302xA-D provide substantially the same output state to the electrodes of the multipole structure 310A-D, the deflection structure (such as 350A-D) in each layer can deflect the electron beam at substantially the same deflection angle. In another example, when its corresponding driver system (e.g., 301yA-D and 302xA-D) provides different output states to the electrodes of its corresponding multipole structure (e.g., 310A-D), the deflection structure (e.g., 350A-D) in each layer can deflect the electron beam at different deflection angles.

[0066] In some embodiments, one or more multilayers (such as the layer comprising deflection structure 350D) may be implemented with a driver system that includes a linear amplifier with a limited output voltage swing to provide finer deflection control by enabling embodiments to provide a high resolution output voltage to an electrode in a layer of the multilayer structure. For example, when a scanning deflection system in an electron beam inspection system is configured to deflect an electron beam with a deflection equivalent to applying 155V to a single conventional multipole structure of the same size as one of 310A-D, a controller may configure switches connected to the multipole structures (such as one of 350A-C) to deliver 50V from a discrete power supply implemented in each deflection structure. Thus, Figure 3B The electrode pairs in three of the four multipole structures in the can be connected to -25V and +25V, respectively. To achieve the equivalent of applying 5V to a conventional multipole structure of the same size, the controller can configure the deflection structure (such as 450D) to be implemented by the above-mentioned linear amplifier, supplying -2.5V and 2.5V to the multipole structure. However, because the range of this linear amplifier is much more limited than that required by existing deflectors, it may be easier to implement, faster, lower power, etc. than existing deflectors.

[0067] Now to Figure 5 Reference is made to FIG. 5 , which shows a schematic diagram of an exemplary system 500 for image disturbance compensation consistent with an embodiment of the present disclosure. The system 500 may be Figure 1 EBI system 100, Figure 2AElectron beam tool 104 or Figure 2B Part of the electron beam tool 100B.

[0068] In some embodiments, the system 500 may include a calibration system 510 and a compensation system 550. Although different modules or components are shown in the calibration system 510 and the compensation system 550, it should be understood that the modules and components of the calibration system 510 and the compensation system 550 are not limited to Figure 5 The configuration shown in .

[0069] In some embodiments, the calibration system 510 may include a power supply line 511 connected to a power source of the system 500 (e.g., an imaging system). In some embodiments, the calibration system 510 may include a reference generator 512 that may generate a reference signal based on a power input from the power supply line 511. The calibration system 510 may include a scan signal generator 513 that may generate a signal indicating the start of a scan of a sample in the system 500. For example, the generated scan signal may be transmitted to a deflection driver 553 (e.g., a compensation system 550). Figure 2A A deflection driver of a deflection scanning unit 232; Figure 2B A deflection driver of the deflector 132c; Figure 3A , Figure 4A and Figure 4B A first drive system 301y; Figure 3A A second drive system 302x; Figure 3B Drive system 301yA-D; Figure 3B The driver system 302xA-D of the power supply line 511 can be used to start scanning and image generation in the system 500. In some embodiments, the generated image can be an image of a sample having a line pattern, but the line pattern in the generated image can include a disturbance with a periodic pattern induced by the power supply line 511 (e.g., Figure 6B For example, the disturbance pattern of the features on the generated image may be expressed in terms of phase and amplitude rather than straight lines (e.g., Fig. 6A 610).

[0070] In some embodiments, the calibration system 510 may include an x-scan extraction module 514 and a y-scan extraction module 515. The x-scan extraction module 514 may extract the amplitude and phase of the disturbance pattern in the generated image in a first direction (e.g., the "x" direction), while the y-scan extraction module 515 may extract the amplitude and phase of the disturbance pattern in the generated image in a second direction (e.g., the "y" direction). In some embodiments, the x-scan extraction module 514 and the y-scan extraction module 515 may use image vibration analysis of the disturbance pattern of the image to extract the phase of the disturbance pattern in the first direction and the second direction. In some embodiments, the image vibration analysis may include characterizing the disturbance pattern of the image (e.g., identifying the shape or pattern characteristics of the disturbance pattern of the image). In some embodiments, the image vibration analysis may include applying an image line pattern edge extraction algorithm to obtain an image vibration signal for analysis in the time domain and the frequency domain.

[0071] In some embodiments, the calibration system 510 may include a calibration module 516. The calibration module 516 may combine a reference signal transmitted from the reference generator 512, a scan signal transmitted from the scan signal generator 513, a first direction amplitude and phase transmitted from the x scan extraction module 514, and a second direction amplitude and phase transmitted from the module y scan extraction module 515 to generate a calibration signal. In some embodiments, the calibration signal may be generated by aligning the scan signal with the reference signal to obtain a phase relationship between the scan signal and the reference signal. In some embodiments, the calibration signal may include a frequency, amplitude, and phase of a disturbance pattern compared to the reference signal (e.g., the calibration signal may include a difference in frequency, amplitude, and phase between the disturbance pattern and the reference signal). In some embodiments, the calibration signal may include a frequency, amplitude, and phase of a disturbance pattern in a first direction and a frequency, amplitude, and phase of a disturbance pattern in a second direction.

[0072] In some embodiments, the compensation system 550 may include a compensation signal generator 551, which may generate a compensation signal by combining a calibration signal transmitted from the calibration module 516 and a reference signal transmitted from the reference generator 512. The generated compensation signal may include image coordinates for adjusting the generated image in the first direction and image coordinates for adjusting the generated image in the second direction.

[0073] In some embodiments, the compensation system 550 may include a coordinate converter 552 that can convert image coordinates associated with the compensation signal transmitted from the compensation signal generator 551 into deflection drive coordinates. In some embodiments, the coordinate converter 552 can transmit the compensation signal including the deflection drive coordinates to the deflection drive 553. The compensation signal can be used to control the deflection drive 553, which is used to manipulate the charged particles to scan the sample to generate an image with reduced image disturbance based on the power input (e.g., to generate an image without image disturbance). In some embodiments, the deflection drive coordinates may include coordinates in a first direction and coordinates in a second direction. In some embodiments, the system 500 can generate a calibration signal and a compensation signal once in some time period (e.g., for a certain number of sample scans).

[0074] Now to Fig. 6A and Figure 6B Reference is made to an exemplary generated image of a line pattern on a sample consistent with embodiments of the present disclosure. Fig. 6A The generated image 600A and Fig. 6A The generated image 600B may be a top view of the sample in the first direction “x” and the second direction “y”.

[0075] like Fig. 6A As shown in , the generated image 600A of the line pattern 610 may include lines 612 that are free of image disturbances induced by the power lines. Figure 6B Generated image 600B is shown of line pattern 620, which may include line 622. Line 622 includes image perturbations induced by the power lines having a periodic pattern. For example, the perturbation pattern of line 622 in generated image 600B may be characterized by phase and amplitude rather than by straight lines.

[0076] Now to Figure 7 For reference, the flowchart illustrates an exemplary process 700 for image disturbance compensation consistent with embodiments of the present disclosure. For illustrative purposes, the steps of the method 700 may be performed or otherwise performed using a computing device (e.g., Figure 1 Controller 109, Figure 5 system 500 or any component thereof) characterized by a system (e.g., Figure 5 It should be appreciated that the illustrated method 700 may be altered to modify the order of steps and include additional steps that may be performed by the system.

[0077] At step 701, a component (e.g., Figure 5 The reference generator 512 can be based on the power supply line (e.g., Figure 5The power input of the power supply line 511) generates a reference signal, and the components (e.g., Figure 5 The scanning signal generator 513 of the embodiment can generate a signal indicating the scanning of the sample (for example, Figure 5 For example, the generated scanning signal can be transmitted to a deflection driver ( Figure 2A A deflection driver of a deflection scanning unit 232; Figure 2B A deflection driver of the deflector 132c; Figure 3A , Figure 4A and Figure 4B A first drive system 301y; Figure 3A A second drive system 302x; Figure 3B Drive system 301yA-D; Figure 3B The driver system 302xA-D of the present invention can be used to start scanning the sample for generating an image. In some embodiments, the generated image can be an image of a sample having a line pattern, but the line pattern in the generated image can include a disturbance with a periodic pattern caused by the power supply line. For example, the disturbance pattern of the feature on the generated image can be characterized by phase and amplitude instead of straight lines.

[0078] At step 703, a component (eg, Figure 5 The x-scan extraction module 514 and the y-scan extraction module 515 of the image can extract the first disturbance data and the second disturbance data from the image generated according to the scan. In some embodiments, the first disturbance data may include the amplitude and phase of the disturbance pattern in the generated image in a first direction (e.g., the "x" direction), and the second disturbance data may include the amplitude and phase of the disturbance pattern in the generated image in a second direction (e.g., the "y" direction). In some embodiments, the component can use image vibration analysis of the disturbance pattern of the image to extract the phase of the disturbance pattern in the first direction and the second direction. In some embodiments, the image vibration analysis may include characterizing the disturbance pattern of the image (e.g., identifying the shape or pattern characteristics of the disturbance pattern of the image). In some embodiments, the image vibration analysis may include applying an image line pattern edge extraction algorithm to obtain an image vibration signal for analysis in the time domain and the frequency domain.

[0079] At step 705, a component (e.g., Figure 5The calibration module 516 of the embodiment of the present invention can combine the reference signal, the scanning signal, the first direction amplitude and phase, and the second direction amplitude and phase to generate a calibration signal. In some embodiments, the calibration signal can be generated by aligning the scanning signal with the reference signal to obtain a phase relationship between the scanning signal and the reference signal. In some embodiments, the calibration signal may include the frequency, amplitude, and phase of the disturbance pattern compared to the reference signal (for example, the calibration signal may include the difference in frequency, amplitude, and phase between the disturbance pattern and the reference signal). In some embodiments, the calibration signal may include the frequency, amplitude, and phase of the disturbance pattern in the first direction and the frequency, amplitude, and phase of the disturbance pattern in the second direction.

[0080] At step 707, a component (eg, Figure 5 The compensation signal generator 551) can generate a compensation signal by combining the calibration signal and the transmitted reference signal. The generated compensation signal may include image coordinates for adjusting the generated image in the first direction and image coordinates for adjusting the generated image in the second direction.

[0081] At step 709, a component (eg, Figure 5 The coordinate converter 552 of the embodiment can convert the image coordinates associated with the compensation signal into deflection driver coordinates, and use the compensation signal to control multiple deflection drivers, which are used to manipulate charged particles to scan the sample. In some embodiments, the deflection driver coordinates can include coordinates in the first direction and coordinates in the second direction.

[0082] A non-transitory computer-readable medium consistent with embodiments of the present disclosure may be provided that stores an electron beam tool or other system (e.g., Figure 5 Calibration system 510, Figure 5 A controller (eg, Figure 1The instructions of the controller 109 of the embodiment of the present invention can be used to execute the instructions of the controller 109 of the embodiment of the present invention. These instructions can allow one or more processors to perform image perturbation compensation, image processing, data processing, beamlet scanning, graphic display, operation of a charged particle beam device or another imaging device, etc. In some embodiments, a non-transitory computer readable medium can be provided, which is an instruction for the processor 700 to store the steps of the execution process 700. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, tapes or any other magnetic data storage media, compact disk read-only memories (CD-ROMs), any other optical data storage media, any physical media with a hole pattern, random access memory (RAM), programmable read-only memory (PROM) and erasable programmable read-only memory (EPROM), FLASH-EPROM or any other flash memory, non-volatile random access memory (NVRAM), caches, registers, any other memory chips or cassettes, and networked versions thereof.

[0083] The embodiments may be further described using the following terms:

[0084] 1. A method comprising:

[0085] generating a reference signal based on a power input to the imaging system;

[0086] generating a scanning signal indicative of a scan of the sample;

[0087] extracting first perturbation data and second perturbation data from an image generated according to the scan;

[0088] generating a calibrated frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scanning signal;

[0089] combining the calibrated frequency, amplitude, and phase of the image perturbation with a reference signal to generate a compensation signal; and

[0090] The compensation signal is used to control a plurality of deflection actuators that are used to steer the charged particles to scan the sample.

[0091] 2. A method according to clause 1, wherein the image perturbation comprises a pattern of features in the generated image.

[0092] 3. The method of clause 2, wherein generating a calibrated frequency, amplitude, and phase of the image perturbation comprises characterizing a pattern.

[0093] 4. A method according to any one of clauses 2 to 3, wherein the pattern is periodic.

[0094] 5. A method according to any one of clauses 1 to 4, wherein manipulating the charged particles to scan the sample reduces image perturbations caused by power input.

[0095] 6. The method according to any one of claims 1 to 5, wherein the first disturbance data comprises the amplitude and phase of the image disturbance in the first direction, and the second disturbance data comprises the amplitude and phase of the image disturbance in the second direction.

[0096] 7. The method of clause 6, wherein the compensation signal comprises image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drives.

[0097] 8. The method of clause 7, further comprising transforming image coordinates of the compensation signal into deflection actuator coordinates to control a plurality of deflection actuators.

[0098] 9. A method comprising:

[0099] generating a reference signal based on a power input to the imaging system;

[0100] generating a scanning signal indicative of a scan of the sample;

[0101] extracting a frequency curve of image perturbations from an image generated from the scan;

[0102] generating a calibration signal based on the reference signal and the extracted frequency curve;

[0103] generating a compensation signal using the calibration signal and the reference signal;

[0104] transforming image coordinates associated with the compensation signal into deflection actuator coordinates; and

[0105] The deflection actuator coordinates of the compensation signal are used to control a plurality of deflection actuators that are used to manipulate the charged particles to scan the sample.

[0106] 10. The method of clause 9, wherein the image perturbation comprises a pattern of features in the generated image.

[0107] 11. The method of clause 10, wherein generating the calibration signal comprises characterizing a pattern.

[0108] 12. A method according to any of clauses 10 to 11, wherein the pattern is periodic.

[0109] 13. A method according to any of clauses 9 to 12, wherein manipulating the charged particles to scan the sample reduces image perturbations caused by power input.

[0110] 14. A method according to any one of clauses 9 to 13, wherein the frequency curve of the image perturbation comprises the amplitude and phase of the image perturbation in the first direction and the amplitude and phase of the image perturbation in the second direction

[0111] 15. The method of clause 14, wherein the compensation signal comprises image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drives.

[0112] 16. The method of clause 15, further comprising transforming image coordinates of the compensation signal into deflection actuator coordinates to control a plurality of deflection actuators.

[0113] 17. A non-transitory computer readable medium comprising an instruction set executable by one or more processors of a device to cause the device to perform a method comprising:

[0114] generating a reference signal based on a power input to the imaging system;

[0115] generating a scanning signal indicative of a scan of the sample;

[0116] extracting first perturbation data and second perturbation data from an image generated according to the scan;

[0117] generating a calibrated frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scanning signal;

[0118] combining the calibrated frequency, amplitude, and phase of the image perturbation with a reference signal to generate a compensation signal; and

[0119] The compensation signal is used to control a plurality of deflection actuators that are used to steer the charged particles to scan the sample.

[0120] 18. The non-transitory computer-readable medium of clause 17, wherein the image perturbation comprises a pattern of features in the generated image.

[0121] 19. The non-transitory computer-readable medium of clause 18, wherein generating a calibrated frequency, amplitude, and phase of the image perturbation comprises characterizing a pattern.

[0122] 20. The non-transitory computer readable medium of any of clauses 18 to 19, wherein the pattern is periodic.

[0123] 21. The non-transitory computer readable medium of any one of clauses 17 to 20, wherein manipulating the charged particles to scan the sample reduces image perturbations caused by power input.

[0124] 22. A non-transitory computer readable medium according to any one of clauses 17 to 21, wherein the first disturbance data comprises an amplitude and a phase of the image disturbance in a first direction, and the second disturbance data comprises an amplitude and a phase of the image disturbance in a second direction.

[0125] 23. A non-transitory computer-readable medium as described in claim 22, wherein the compensation signal includes image coordinates of the generated image in a first direction and image coordinates of the generated image in a second direction, wherein the image coordinates of the generated image lack coordinates for controlling multiple deflection drives.

[0126] 24. The non-transitory computer readable medium of clause 23, wherein the set of instructions is executable by at least one processor of a computing device to cause the computing device to further perform transforming image coordinates of the compensation signal into deflection actuator coordinates to control a plurality of deflection actuators.

[0127] 25. A non-transitory computer readable medium comprising an instruction set executable by one or more processors of a device to cause the device to perform a method comprising:

[0128] generating a reference signal based on a power input to the imaging system;

[0129] generating a scanning signal indicative of a scan of the sample;

[0130] extracting a frequency curve of image perturbations from an image generated from the scan;

[0131] generating a calibration signal based on the reference signal and the extracted frequency curve;

[0132] generating a compensation signal using the calibration signal and the reference signal;

[0133] transforming image coordinates associated with the compensation signal into deflection driver coordinates; and

[0134] The deflection actuator coordinates of the compensation signal are used to control a plurality of deflection actuators that are used to manipulate the charged particles to scan the sample.

[0135] 26. The non-transitory computer-readable medium of clause 25, wherein the image perturbation comprises a pattern of features in the generated image.

[0136] 27. The non-transitory computer-readable medium of clause 26, wherein generating the calibration signal comprises characterizing the pattern.

[0137] 28. The non-transitory computer readable medium of any of clauses 26 to 27, wherein the pattern is periodic.

[0138] 29. The non-transitory computer readable medium of any one of clauses 25 to 28, wherein manipulating the charged particles to scan the sample reduces image perturbations caused by power input.

[0139] 30. The non-transitory computer-readable medium of any one of clauses 25 to 29, wherein the frequency curve of the image perturbation comprises an amplitude and a phase of the image perturbation in a first direction and an amplitude and a phase of the image perturbation in a second direction.

[0140] 31. A non-transitory computer-readable medium as described in claim 30, wherein the compensation signal includes image coordinates of the generated image in a first direction and image coordinates of the generated image in a second direction, wherein the image coordinates of the generated image lack coordinates for controlling multiple deflection drives.

[0141] 32. The non-transitory computer readable medium of clause 31, wherein the set of instructions is executable by at least one processor of a computing device to cause the computing device to further perform transforming image coordinates of the compensation signal into deflection actuator coordinates to control a plurality of deflection actuators.

[0142] 33. A system comprising:

[0143] One or more processors configured to execute instructions to cause the system to perform:

[0144] generating a reference signal based on a power input to the imaging system;

[0145] generating a scanning signal indicative of a scan of the sample;

[0146] extracting first perturbation data and second perturbation data from an image generated according to the scan;

[0147] generating a calibrated frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scanning signal;

[0148] combining the calibrated frequency, amplitude, and phase of the image perturbation with a reference signal to generate a compensation signal; and

[0149] The compensation signal is used to control a plurality of deflection actuators that are used to steer the charged particles to scan the sample.

[0150] 34. A system according to clause 33, wherein the image perturbation comprises a pattern of features in the generated image.

[0151] 35. A system according to clause 34, wherein generating a calibrated frequency, amplitude, and phase of the image perturbation includes characterizing a pattern.

[0152] 36. A system according to any of clauses 34 to 35, wherein the pattern is periodic.

[0153] 37. A system according to any of clauses 33 to 36, wherein manipulating the charged particles to scan the sample reduces image perturbations caused by power input.

[0154] 38. A system according to any one of clauses 33 to 37, wherein the first perturbation data comprises an amplitude and a phase of an image perturbation in a first direction, and the second perturbation data comprises an amplitude and a phase of an image perturbation in a second direction.

[0155] 39. A system according to clause 38, wherein the compensation signal includes image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drives.

[0156] 40. The system of clause 39, wherein the one or more processors are configured to execute the instructions to cause the system to further perform:

[0157] The image coordinates of the compensation signal are transformed into deflection actuator coordinates to control the plurality of deflection actuators.

[0158] 41. A system comprising:

[0159] One or more processors configured to execute instructions to cause the system to perform:

[0160] generating a reference signal based on a power input to the imaging system;

[0161] generating a scanning signal indicative of a scan of the sample;

[0162] extracting a frequency curve of image perturbations from an image generated from the scan;

[0163] generating a calibration signal based on the reference signal and the extracted frequency curve;

[0164] generating a compensation signal using the calibration signal and the reference signal;

[0165] transforming image coordinates associated with the compensation signal into deflection actuator coordinates; and

[0166] The deflection actuator coordinates of the compensation signal are used to control a plurality of deflection actuators that are used to manipulate the charged particles to scan the sample.

[0167] 42. The system of clause 41, wherein the image perturbation comprises a pattern of features in the generated image.

[0168] 43. The system of clause 42, wherein generating the calibration signal comprises characterizing a pattern.

[0169] 44. A system according to any of clauses 42 to 43, wherein the pattern is periodic.

[0170] 45. A system according to any of clauses 41 to 44, wherein manipulating charged particles to scan the sample reduces image perturbations caused by power input.

[0171] 46. ​​A system according to any of clauses 41 to 45, wherein the frequency curve of the image perturbation comprises the amplitude and phase of the image perturbation in a first direction and the amplitude and phase of the image perturbation in a second direction.

[0172] 47. A system according to clause 46, wherein the compensation signal includes image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drives.

[0173] 48. The system of clause 47, wherein the one or more processors are configured to execute instructions to cause the system to perform:

[0174] The image coordinates of the compensation signal are transformed into deflection actuator coordinates to control the plurality of deflection actuators.

[0175] It should be understood that the embodiments of the present disclosure are not limited to the exact constructions described above and illustrated in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A non-transitory computer-readable medium comprising an instruction set, the instruction set being executable by one or more processors of a device to cause the device to perform a method, the method comprising: generating a reference signal based on a power input to the imaging system; generating a scanning signal indicative of a scan of the sample; extracting first perturbation data and second perturbation data from an image generated from the scanning; generating a calibration frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scanning signal; combining the calibrated frequency, amplitude and phase of the image perturbation with the reference signal to generate a compensation signal; as well as The compensation signal is used to control a plurality of deflection actuators that are used to steer charged particles to scan the sample. 2 . The non-transitory computer readable medium of claim 1 , wherein the image perturbation comprises a pattern of features in the generated image. 3 . The non-transitory computer readable medium of claim 2 , wherein generating the calibrated frequency, amplitude, and phase of the image perturbation comprises characterizing the pattern. The non-transitory computer readable medium of claim 2 , wherein the pattern is periodic.

5. The non-transitory computer readable medium of claim 1, wherein manipulating charged particles to scan the sample reduces image perturbations caused by the power input. 6 . The non-transitory computer readable medium of claim 1 , wherein the first disturbance data comprises an amplitude and a phase of an image disturbance in a first direction, and the second disturbance data comprises an amplitude and a phase of an image disturbance in a second direction.

7. The non-transitory computer-readable medium of claim 6, wherein the compensation signal comprises image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drives.

8. The non-transitory computer readable medium of claim 7, wherein the set of instructions is executable by at least one processor of a computing device to cause the computing device to further perform transforming the image coordinates of the compensation signal into deflection drive coordinates to control the plurality of deflection drives.

9. A system comprising: One or more processors configured to execute instructions to cause the system to perform: generating a reference signal based on a power input to the imaging system; generating a scanning signal indicative of a scan of the sample; extracting first perturbation data and second perturbation data from an image generated from the scanning; generating a calibration frequency, amplitude and phase of the image perturbation using the extracted first and second perturbation data, the reference signal and the scanning signal; combining the calibrated frequency, amplitude and phase of the image perturbation with the reference signal to generate a compensation signal; as well as The compensation signal is used to control a plurality of deflection actuators that are used to steer charged particles to scan the sample.

10. The system of claim 9, wherein the image perturbation comprises a pattern of features in the generated image.

11. The system of claim 10, wherein generating the calibrated frequency, amplitude, and phase of the image perturbation comprises characterizing the pattern.

12. The system of claim 10, wherein the pattern is periodic.

13. The system of claim 9, wherein manipulating charged particles to scan the sample reduces image perturbations caused by the power input.

14. The system of claim 9, wherein the first perturbation data comprises an amplitude and a phase of an image perturbation in a first direction, and the second perturbation data comprises an amplitude and a phase of an image perturbation in a second direction.

15. The system of claim 14, wherein the compensation signal comprises image coordinates of the generated image in the first direction and image coordinates of the generated image in the second direction, wherein the image coordinates of the generated image lack coordinates for controlling the plurality of deflection drivers.

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