Direct aberration retrieval for charged particle devices

Abstract

A system and method for aberration detection in a charged particle beam system, such as a scanning electron microscope. The method determines a characteristic of the incident beam on the sample using spatial information of the charged particles on the detector surface reaching the position of incidence of the event. Beam parameters, such as beam tilt, defocus, spherical aberration, chromatic aberration, coma, diffraction error, astigmatism, field curvature, distortion, and the like, may have a identifiable relationship with the final spatial distribution that may be used to identify and correct beam aberration by irradiating flat, open surface regions on the sample.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Application 63 / 514,543, filed on July 19, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This article describes charged particle beam systems, and more particularly, systems and methods for determining beam aberrations in such charged particle beam systems. Background Technology

[0003] Detectors can be used to sense physically observable phenomena. For example, charged particle beam tools such as electron microscopes can include detectors that receive charged particles projected from a sample and output a detection signal. The detection signal can be used to reconstruct an image of the structure of the sample under inspection and can be used, for example, for measurement processes or to reveal defects in the sample. Measurement involves the precise measurement of sample structure and other miniaturized features. For example, in semiconductor wafers, measurement can include measurements of circuit pattern features such as critical dimensions (the width of the smallest device feature), critical dimension uniformity, linewidth, overlay, line edge roughness, line tip shortening, ground plane tilt, sidewall angles, and other dimensional parameters. In the manufacture of semiconductor devices, the detection of defects in samples that may include a large number of densely packed miniaturized integrated circuit (IC) components is also increasingly important. Inspection systems can be provided for these and other purposes.

[0004] As semiconductor devices continue to miniaturize, the performance requirements for detection systems are likely to continue to increase. To ensure optimal imaging performance, it is crucial to measure the parameters of charged particle beams with high accuracy, consistency, and speed. For example, beam aberrations, such as beam tilt, defocus, spherical aberration, chromatic aberration, coma, diffraction error, astigmatism, field curvature, distortion, and others, must be determined to correct these aberrations and maintain high-performance imaging. Summary of the Invention

[0005] Embodiments of this disclosure provide systems and methods for determining beam aberrations in a charged particle beam system. Some embodiments of this disclosure provide a charged particle beam method. The method may include: irradiating a surface with a charged particle beam using a charged particle beam system; obtaining spatial distribution information of the arrival of charged particles detected on a charged particle detector; determining aberration values ​​of the charged particle beam based on the spatial distribution information; and performing adjustments to the charged particle beam system based on the determined aberration values.

[0006] Some embodiments of this disclosure provide a charged particle beam device. The charged particle beam device may include: a charged particle beam source configured to generate a primary charged particle beam; a charged particle optical system configured to guide the primary charged particle beam to a surface; and a controller including one or more processors and configured to cause the charged particle beam device to perform operations including the above method steps.

[0007] Some embodiments of this disclosure provide a non-transitory computer-readable medium storing an instruction set. This instruction set can be executed by at least one processor of a device to cause the device to perform operations including the method steps described above. Attached Figure Description

[0008] The above and other aspects of this disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a schematic representation of an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0010] Figures 2A to 2C This is a diagram illustrating an example of a charged particle beam device that may be an electron beam tool, consistent with embodiments of the present disclosure.

[0011] Figure 2D The illustration shows the electron arrival distribution on an exemplary detector in a charged particle beam apparatus consistent with embodiments of the present disclosure.

[0012] Figures 3A to 3B This is a schematic representation illustrating an exemplary structure of a detector in a charged particle beam apparatus consistent with embodiments of the present disclosure.

[0013] Figures 4A to 4F The illustration shows example spatial distribution information of electron arrival locations on a pixelated detector surface consistent with embodiments of the present disclosure.

[0014] Figure 5 The illustration shows example spatial distribution information of electron arrival locations on a segmented detector surface consistent with embodiments of the present disclosure.

[0015] Figure 6A The illustration shows a flowchart of an example method for determining beam aberrations in a charged particle beam detection process consistent with some embodiments of this disclosure.

[0016] Figures 6B to 6C The illustration shows a flowchart of an example method for determining reference information for aberration measurements in a charged particle beam detection process, consistent with embodiments of the present disclosure.

[0017] Figure 7The illustration shows a flowchart of an example method for determining beam aberrations in a charged particle beam detection process consistent with some embodiments of this disclosure. Detailed Implementation

[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 numerals in different drawings denote the same or similar elements. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatuses, systems, and methods consistent with various aspects of the subject matter that may be recited in the appended claims. For example, although some embodiments are described in the context of using charged particle beams (electron beams), this disclosure is not limited thereto. Other types of charged particle beams, such as proton beams, can be applied similarly. Furthermore, other imaging systems can be used, such as optical imaging, photoelectric detection, X-ray detection, etc.

[0019] Electronic devices consist of circuits formed on a silicon wafer called a substrate. Many circuits can be formed together on the same silicon wafer and are called integrated circuits or ICs. As technology advances, the size of these circuits has drastically decreased, allowing even more circuits to be mounted on the substrate. For example, the IC chip in a smartphone can be as small as a fingernail but can include more than 2 billion transistors, each less than 1 / 1000th the width of a human hair.

[0020] Manufacturing these ICs, which have extremely small structures or components, is a complex, time-consuming, and expensive process, typically involving hundreds of individual steps. Even an error in one step can result in a defective IC that renders it unusable. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process, i.e., to increase the overall yield of the process.

[0021] A key component of increasing throughput is monitoring the chip manufacturing process to ensure it produces a sufficient number of functional integrated circuits. One way to monitor this process is to inspect it at various stages of chip circuit structure formation. Inspections can be performed using scanning charged particle microscopy, such as scanning electron microscopy (SEM). SEM can be used to image these extremely small structures, essentially taking "photographs" of them. This image can be used to determine if the structure is formed correctly and in the correct location. If a defect is found, the process can be adjusted to make it less likely to recur. To increase throughput (e.g., the number of samples processed per hour), frequent inspections are desirable.

[0022] A SEM works similarly to a camera. A camera takes a picture by receiving and recording the intensity of light reflected or emitted from a person or object pixel by pixel. A SEM takes a "picture" by receiving and recording the energy or number of electrons reflected or emitted from a wafer structure. Before taking this "picture," an electron beam can be projected onto the structure, and as electrons reflect or are emitted ("leave") from the structure (e.g., from the wafer surface, from a structure below the wafer surface, or both), the SEM's detector can receive and record the energy or number of these electrons to generate an inspection image. To take this "picture," the electron beam can scan the wafer (e.g., in a line-by-line or zigzag pattern), and the detector can receive the leaving electrons from the area where the electron beam is projected (called a "beam spot"). The detector can receive and record leaving electrons from each beam spot each time, and combine the information recorded for all beam spots to generate an inspection image. Some SEMs use a single electron beam (called "single-beam SEM") to capture a single "photograph" to generate an inspection image, while others use multiple electron beams (called "multi-beam SEM") to capture multiple "sub-photographs" of the wafer in parallel and, in some instances, stitch them together to generate an inspection image. By using multiple electron beams, the SEM can provide more electron beams to the structure to obtain these multiple "sub-photographs," thus allowing more electrons to leave the structure. Therefore, the detector can receive more leaving electrons simultaneously and generate inspection images of the wafer structure with greater efficiency and faster speed.

[0023] In some inspection processes, such as critical dimension (CD) measurement, charged particle imaging can be used to measure the width of the smallest feature printed on a sample to determine how well the printed pattern meets design specifications. For example, an electron beam can scan the surface topography of a pattern, such as a set of repeating lines and spaces, performing pixel-by-pixel intensity measurements in the scanning process. Each line can have a substantially flat, raised upper surface. The lower spaces between each line can also be relatively flat, while the transitions between lines and spaces can include sharp vertical edges. In electron beam imaging, the pixel intensity at these edge transitions can contrast sharply with the surrounding flat areas, providing a way to measure the width of these features.

[0024] To ensure high-quality imaging, various characteristics of the electron beam must be measured and adjusted. For example, the angular spread of electrons striking the sample, the varying energies of electrons within the beam, the cross-sectional shape of the beam, and the beam's (multiple) focal points can all distort or deviate from their expected values ​​in complex ways. These beam deviations and distortions are commonly referred to as aberrations. Typical low-order aberrations can include, for example, focusing, beam tilt, distortion, or astigmatism. Generally, any non-idealities in the electrons' position, angle, or energy on the sample can be attributed to aberrations. Because even small aberration values ​​can degrade the quality of electron beam images, measuring them and performing appropriate corrections is crucial.

[0025] One problem with existing aberration measurement methods is that they can be very time-consuming. For example, a measurement process may require capturing a series of test images of a test pattern. The test pattern can be located on the test wafer or on the surface of a chuck supporting the wafer. Many different micron or nanometer-scale test structures can be formed on the test pattern, and it can be designed to be sensitive to different types of aberrations. The electron beam system can scan the test pattern at several different focus levels or at various other settings of the electron beam optics. For example, the electron beam system can scan the test pattern at several different landing energies to obtain information about, for example, chromatic aberration. The obtained images can be examined to determine the various aberration values ​​that may be present in the electron beam system and to perform adjustments. Because electron beam scanning is very time-consuming, this monitoring process wastes valuable production time. For example, acquiring a single high-resolution defect inspection image of an entire 300 mm wafer at 12.5 megapixels per second could take, for example, 20 hours or more. Spending time defocusing the test area reduces throughput in this process.

[0026] For example, measuring focusing might require taking a series of images, such as ten images, at each of multiple test locations at different focus levels. While each series of images might take, for example, a few seconds, there could be multiple test locations on the wafer, and the measurements might be performed frequently. Therefore, a complete interruption of the scan time is generally detrimental. Other aberration measurements might take even longer. For example, to characterize astigmatism correction in an electron beam system, multiple images can be taken at multiple focus and astigmatism correction values. While typically performed less frequently than focusing measurements (e.g., approximately several hours), these measurements might still take much longer, such as, for example, several minutes.

[0027] A particularly challenging aspect of routine aberration measurements involves more complex tasks such as identifying and troubleshooting distortions in electron beam tools. Distortion monitoring may require, for example, hundreds of images, and troubleshooting can result in the machine being offline for several days.

[0028] Another problem with existing aberration measurement methods is that they are not performed under realistic conditions. For example, the action of repositioning the scanning beam to a specific location for testing requires additional time and introduces the risk that the aberration state at the test area may differ from the aberration state at the actual inspection location. Furthermore, as mentioned above, the test pattern can be scanned under a series of different focusing settings, rather than the settings applied during actual imaging inspection. Because the beam is measured under different optical settings than those used in operation, it is difficult to accurately predict the true beam aberrations.

[0029] Embodiments of this disclosure provide systems and methods for determining beam aberrations in charged particle beam systems, such as scanning electron microscopes. Instead of acquiring and analyzing a series of test images under various focusing settings, this system can utilize information about the spatial distribution of electrons emitted from a sample to a detector surface. It has been found that the size, shape, and other properties of these electron distributions are directly related to the aberration values ​​of the incoming electron beam. For example, an ideal electron beam might strike a wafer and produce a stream of emitted electrons that lands on the detector in a symmetrical circular distribution. On the other hand, an aberrated beam might produce a stream of emitted electrons that results in a distorted or asymmetrical distribution. By mapping the distribution shape to corresponding beam characteristics, aberration values ​​can be measured more quickly, even in real time during normal scanning operations. Furthermore, the beam can be measured under real-world beam settings, improving accuracy and enhancing electron imaging. The time required for measuring distortion, troubleshooting, and other time-consuming tasks can be significantly reduced.

[0030] In some conventional systems, the exact location on the detector surface where the emitted electrons land may not matter. For any given image pixel, only the total intensity from the detector (determined by the total number of electrons / energy) is recorded. Therefore, not all detectors can be configured to perform the disclosed method because they cannot distinguish the exact location of the electron landing on the surface. However, by using a detector surface capable of distinguishing different electron landing locations, the spatial distribution of electrons on the detector can be determined.

[0031] The purposes and advantages of this disclosure can be achieved by the elements and combinations set forth in the embodiments discussed herein. However, embodiments of this disclosure are not necessarily required to achieve such exemplary purposes or advantages, and some embodiments may not achieve any of the described purposes or advantages.

[0032] As used herein, unless otherwise specified, the term "or" covers all possible combinations except where impractical. For example, if a descriptive component includes A or B, then unless otherwise specified or impractical, the component may include A or B or A and B. As a second example, if a descriptive component includes A, B, or C, then unless otherwise specified or impractical, 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.

[0033] Now for reference Figure 1 , Figure 1 An exemplary electron beam inspection (EBI) system 10, consistent with embodiments of this disclosure, is illustrated and can be used for wafer inspection. For example... Figure 1 As shown, the EBI system 10 includes a main chamber 11, a loading / locking chamber 20, an electron beam tool 100 (e.g., a scanning electron microscope (SEM)), and an equipment front-end module (EFEM) 30. The electron beam tool 100 is located within the main chamber 11 and can be used for imaging. The EFEM 30 includes a first loading port 30a and a second loading port 30b. The EFEM 30 may include additional loading ports. The first loading port 30a and the second loading port 30b accommodate a wafer front-opening transfer cassette (FOUP) containing a wafer (e.g., one or more semiconductor wafers made of other materials) or a sample (wafers and samples may be collectively referred to herein as “wafers”) to be inspected.

[0034] One or more robotic arms (not shown) in EFEM 30 can transport the wafer to loading / locking chamber 20. Loading / locking chamber 20 is connected to a loading / locking vacuum pump system (not shown), which removes gas molecules from loading / locking chamber 20 to achieve a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) can transport the wafer from loading / locking chamber 20 to main chamber 11. Main chamber 11 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from main chamber 11 to achieve a second pressure below the first pressure. After reaching the second pressure, the wafer is inspected by electron beam tool 100. Electron beam tool 100 can be a single-beam system or a multi-beam system. Controller 109 is electronically connected to electron beam tool 100 and can also be electronically connected to other components. Controller 109 can be a computer configured to perform various controls of EBI system 10. Figure 1 The controller 109 is shown outside the structure including the main chamber 11, the loading / locking chamber 20 and the EFEM 30, but it should be understood that the controller 109 may be part of the structure.

[0035] In some embodiments, controller 109 may include one or more processors (not shown). A processor may be a general-purpose or specific electronic device capable of manipulating or processing information. For example, a processor may include any number of central processing units (or “CPU”), graphics processing units (or “GPU”), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general-purpose array logic (GALs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), system-on-a-chip (SoCs), application-specific integrated circuits (ASICs), and any combination of any type of circuitry capable of data processing. A processor may also be a virtual processor, comprising one or more processors distributed across multiple machines or devices coupled via a network.

[0036] In some embodiments, controller 109 may also include one or more memories (not shown). The memory can be a general-purpose or specific electronic device capable of storing processor-accessible (e.g., via a bus) code and data. For example, the memory can include any number of random access memory (RAM), read-only memory (ROM), optical disc, magnetic disk, hard disk, solid-state drive, flash drive, secure digital (SD) card, memory stick, compact flash (CF) card, or any combination of any type of storage device. The code and data can include an operating system (OS) and one or more applications (or "applications") for a specific task. The memory can also be virtual memory, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0037] Charged particle beam microscopy (such as that formed by or included in EBI system 10) can achieve resolutions at the nanometer scale and can serve as a practical tool for inspecting IC components on wafers. Using an electron beam system, electrons from a primary electron beam can be focused onto a probe spot on the wafer to be inspected. The interaction between the primary electrons and the wafer can lead to the formation of a secondary particle beam. The secondary particle beam can include backscattered electrons, secondary electrons, or Auger electrons generated by the interaction between the primary electrons and the wafer. The characteristics (e.g., intensity) of the secondary particle beam can vary based on the internal or external structure or material properties of the wafer, thus indicating whether the wafer contains defects.

[0038] The intensity of the secondary particle beam can be determined using a detector. The secondary particle beam can form a beam spot on the surface of the detector. The detector can generate an electrical signal (e.g., current, charge, voltage, etc.) representing the intensity of the detected secondary particle beam. The electrical signal can be measured using a measurement circuit system, which may include other components (e.g., an analog-to-digital converter), to obtain the distribution of the detected electrons. Combined with the corresponding scan path data of the primary electron beam incident on the wafer surface, the electron distribution data collected during the detection time window can be used to reconstruct an image of the wafer structure or material under inspection. The reconstructed image can be used to reveal various features of the internal or external structure or material of the wafer, and can be used to reveal defects that may exist in the wafer. CD-SEM performs image reconstruction based on signals in two ways: based on the amplitude integration of the signal in each scan pixel; or based on signal pulse edge detection and differentiation. At each scan pixel location, multiple electrical signal pulses collected in segments by different detectors may have different pulse shapes. These different pulse shapes contain information about the energy distribution of the electrons collected by the detector. Electrons with higher energy can cause the rise time of the electrical pulse shape to be faster. By utilizing multiple segments (4 channels) of the detector, up to 4 pulse edge detection image channels can be used to perform electron energy analysis, resulting in higher SEM resolution.

[0039] Figure 2A The illustration shows a charged particle beam device consistent with an embodiment of the present disclosure, which may be an example of an electron beam tool 100. Figure 2A An apparatus is shown that uses multiple beams formed by a primary electron beam to simultaneously scan multiple locations on a wafer.

[0040] like Figure 2A As shown, the electron beam tool 100A may include an electron source 202, a gun aperture 204, a converging lens 206, a primary electron beam 210 emitted from the electron source 202, a source conversion unit 212, multiple beams 214, 216, and 218 of the primary electron beam 210, a primary projection optics system 220, and a wafer platform. Figure 2A (Not shown in the diagram) Multiple secondary electron beams 236, 238, and 240, a secondary optical system 242, and an electron detection device 244. The electron source 202 can generate primary particles, such as electrons from the primary electron beam 210. A controller, image processing system, etc., can be coupled to the electron detection device 244. The primary projection optical system 220 may include a beam splitter 222, a deflection scanning unit 226, and an objective lens 228. The electron detection device 244 may include detection sub-regions 246, 248, and 250.

[0041] The electron source 202, the gun aperture 204, the converging lens 206, the source conversion unit 212, the beam splitter 222, the deflection scanning unit 226, and the objective lens 228 can be aligned with the primary optical axis 260 of the electron beam tool 100A. The secondary optical system 242 and the electronic inspection device 244 can be aligned with the secondary optical axis 252 of the electron beam tool 100A.

[0042] Electron source 202 may include a cathode, extractor, or anode, wherein primary electrons may be emitted from the cathode and extracted or accelerated to form a primary electron beam 210 having a cross (virtual or real) 208. The primary electron beam 210 can be visualized as being emitted from the cross 208. Aperture 204 may block peripheral electrons of the primary electron beam 210 to reduce the size of the probe spots 270, 272, and 274.

[0043] Source conversion unit 212 may include an image forming element array ( Figure 2A (not shown in the image) and beam-limiting aperture array ( Figure 2A (Not shown in the image). Examples of source conversion unit 212 can be found in U.S. Patent No. 9,691,586; U.S. Publication No. 2017 / 0025243; and International Application No. PCT / EP2017 / 084429, all of which are incorporated herein by reference in their entirety. The image forming element array may include an array of microdeflectors or microlenses. The image forming element array may form multiple parallel images (virtual or real) of the multiple beam waves 214, 216, and 218 of the primary electron beam 210 at an intersection 208. The beam-limiting aperture array may limit the multiple beam waves 214, 216, and 218.

[0044] Converging lens 206 can focus primary electron beam 210. The current of beams 214, 216, and 218 downstream of source conversion unit 212 can be changed by adjusting the focusing capability of converging lens 206 or by changing the radial dimension of the corresponding beam-limiting aperture within the beam-limiting aperture array. Converging lens 206 can be an adjustable converging lens, which can be configured such that the position of its first principal plane is movable. The adjustable converging lens can be configured to be magnetic, which can cause off-axis beams 216 and 218 to land on the beam-limiting aperture with a rotation angle. The rotation angle varies with the focusing capability and the position of the first principal plane of the adjustable converging lens. In some embodiments, the adjustable converging lens can be an adjustable anti-rotation converging lens, which relates to an anti-rotation lens having a movable first principal plane. Examples of adjustable converging lenses are also described in U.S. Publication No. 2017 / 0025241, which is incorporated herein by reference in its entirety.

[0045] Objective lens 228 can focus beams 214, 216, and 218 onto wafer 230 for inspection, and can form multiple probe spots 270, 272, and 274 on the surface of wafer 230. Secondary electron beams 236, 238, and 240 can be formed from wafer 230 and return toward beam splitter 222.

[0046] Beam splitter 222 can be a Wien filter type beam splitter that generates electrostatic dipole fields and magnetic dipole fields. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on the electrons of beam waves 214, 216, and 218 on the electrons may be equal in magnitude and opposite in direction to the force exerted by the magnetic dipole field on the electrons. Therefore, beam waves 214, 216, and 218 can pass directly through beam splitter 222 with zero deflection angle. However, the total dispersion of beam waves 214, 216, and 218 generated by beam splitter 222 can also be non-zero. Beam splitter 222 can separate secondary electron beams 236, 238, and 240 from beam waves 214, 216, and 218 and guide secondary electron beams 236, 238, and 240 toward secondary optical system 242.

[0047] The deflection scanning unit 226 can deflect beams 214, 216, and 218 to scan probe spots 270, 272, and 274 on regions of the surface of wafer 230. In response to the incident beams 214, 216, and 218 at probe spots 270, 272, and 274, secondary electron beams 236, 238, and 240 can be emitted from wafer 230. The secondary electron beams 236, 238, and 240 can include electrons with energy distributions, including secondary electrons and backscattered electrons. The secondary optical system 242 can focus the secondary electron beams 236, 238, and 240 onto detection sub-regions 246, 248, and 250 of the electron detection device 244. Detection sub-regions 246, 248, and 250 can be configured to detect the corresponding secondary electron beams 236, 238, and 240 and generate corresponding signals for reconstructing a surface image of wafer 230.

[0048] The generated signals can represent the intensity of the secondary electron beams 236, 238, and 240, and can be provided to an image processing system (e.g., as shown below) that communicates with the detection device 244, the primary projection optics system 220, and the motorized wafer platform. Figure 2BThe image processing system 199 provided in the image processing system 230 can synchronize and coordinate the movement speed of the motorized wafer platform with the beam deflection controlled by the deflection scanning unit 226, so that the movement of the scanning probe spots (e.g., scanning probe spots 270, 272, and 274) can orderly cover the region of interest on the wafer 230. The parameters of this synchronization and coordination can be adjusted to accommodate different materials of the wafer 230. For example, different materials of the wafer 230 may have different resistivity-capacitance characteristics, which may result in different signal sensitivities to the movement of the scanning probe spots.

[0049] The intensities of the secondary electron beams 236, 238, and 240 can vary depending on the external or internal structure of the wafer 230, thus indicating whether the wafer 230 contains defects. Furthermore, as discussed above, beams 214, 216, and 218 can be projected onto different locations on the top surface of the wafer 230 or different sides of a local structure of the wafer 230 to generate secondary electron beams 236, 238, and 240 with varying intensities. Therefore, by mapping the intensities of the secondary electron beams 236, 238, and 240 to regions of the wafer 230, the image processing system can reconstruct an image reflecting the characteristics of the internal or external structure of the wafer 230.

[0050] Detection sub-regions 246, 248, and 250 may include individual detector packages, individual sensing elements, or individual regions of array detectors. In some embodiments, each detection sub-region may include a single sensing element.

[0051] Although Figure 2A The diagram shows detector 244 having several detection sub-regions aligned with the secondary optical axis 252, but it is understood that other multi-beam detector schemes may exist. For example, it is understood that detectors may correspond to each beam, such as different detectors for each of beams 214, 216, 218. It is understood that these different detectors may be positioned below the primary pillar corresponding to the primary axis 260. For example, these different detectors may be positioned between the primary projection optics system 220 and the wafer platform.

[0052] Now refer to Figure 2B Another example of a charged particle beam device is discussed. Electron beam tool 200B (also referred to herein as charged particle device 200B) can be an example of electron beam tool 100 and can be similar to... Figure 2A The electron beam tool 100A is shown. However, unlike the electron beam tool 100A, the electron beam tool 200B can be a single-beam tool, using only one primary electron beam to scan one location on the wafer at a time.

[0053] like Figure 2BAs shown, the apparatus 200B includes a wafer holder 136 supported by a motorized platform 134 for holding a wafer 150 to be inspected. The electron beam tool 200B includes an electron emitter that may include a cathode 103, an anode 121, and a gun aperture 122. The electron beam tool 200B also includes a beam-limiting aperture 125, a converging lens 126, a cylindrical aperture 135, an objective lens assembly 132, and a detector 144. In some embodiments, the objective lens assembly 132 may be a modified SORIL lens, which includes a pole piece 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. In the inspection or imaging process, an electron beam 161 emitted from the tip of the cathode 103 can be accelerated by the voltage of the anode 121, passes through the gun aperture 122, the beam-limiting aperture 125, and the converging lens 126, and is focused by the modified SORIL lens into a probe spot 170 and impacts the surface of the wafer 150. The probe spot 170 can be scanned on the surface of the wafer 150 by a deflector (such as deflector 132c in a SORIL lens or other deflectors). The detector 144 can collect secondary particles or scattered particles (such as secondary electrons emitted from the wafer surface or scattered primary electrons) to determine the beam intensity and make it possible to reconstruct an image of the region of interest on the wafer 150.

[0054] In some embodiments, the wafer holder 136 or platform 134 may include a measurement section 146. The upper surface of the measurement section 146 may be substantially flush with the upper surface of the wafer 150. The measurement section 146 may include reference points or other test patterns for measuring, for example, alignment, focusing, or beam aberrations. In some embodiments, as further discussed below, the measurement section 146 may include a highly flat test surface configured to provide an ideal irradiated surface for detecting aberrations according to the systems and methods of this disclosure. For example, the measurement section 146 may include a highly flat portion having a layer of, for example, a heavy metal such as silver, gold, titanium, cobalt, copper, ruthenium, or another high atomic number (Z) material. This material may be configured to generate a large number of backscattered electrons, thereby improving the signal-to-noise ratio of the measurement. The measurement section 146 may be coupled to a power source configured to apply a desired potential to the test surface to control the emission properties of the emitted electrons.

[0055] An image processing system 199 may also be provided, including an image acquirer 120, a storage device 130, and a controller 109. The image acquirer 120 may include one or more processors. For example, the image acquirer 120 may include a computer, server, mainframe, terminal, personal computer, any kind of mobile computing device, or a combination thereof. The image acquirer 120 may be communicatively coupled to the detector 144 of the electron beam tool 200B via a medium such as an electrical conductor, fiber optic cable, portable storage medium, IR, Bluetooth, Internet, wireless network, radio, or a combination thereof. The image acquirer 120 may receive signals from the detector 144 and may construct an image. The image acquirer 120 may thus acquire an image of the wafer 150. The image acquirer 120 may also perform various post-processing functions, such as image averaging, contour generation, and overlaying indicators on the acquired image. The image acquirer 120 may be configured to perform adjustments such as brightness and contrast of the acquired image. The storage device 130 may be a storage medium such as a hard disk, random access memory (RAM), cloud storage device, or other types of computer-readable storage. Storage device 130 may be coupled to image acquirer 120 and may be used to store scanned original image data as the original image and post-processed images. Image acquirer 120 and storage device 130 may be connected to controller 109. In some embodiments, image acquirer 120, storage device 130 and controller 109 may be integrated into a single electronic control unit.

[0056] In some embodiments, the image acquirer 120 may acquire one or more images of a sample based on an imaging signal received from the detector 144. The imaging signal may correspond to a scanning operation for imaging charged particles. The acquired image may be a single image comprising multiple imaging regions, which may contain 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.

[0057] The converging and illumination optics of an electron beam tool may include or be supplemented by an electromagnetic quadrupole electron lens. For example, such as Figure 2B As shown, the electron beam tool 200B may include a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lens can be used to control the electron beam. For example, the first quadrupole lens 148 can be controlled to adjust the beam current, and the second quadrupole lens 158 can be controlled to adjust the beam spot size and beam shape.

[0058] Figure 2B The illustration depicts a charged particle beam device that can use a single primary beam configured to generate secondary electrons through interaction with a wafer 150. A detector 144 can be positioned along an optical axis 105, as shown. Figure 2BAs in the illustrated embodiment, the primary electron beam can be configured to travel along the optical axis 105. Therefore, the detector 144 can include a hole at its center, allowing the primary electron beam to pass through and reach the wafer 150. Figure 2B An example of a detector 144 with an opening at its center is shown. However, some embodiments may use a detector positioned off-axis relative to the optical axis along which the primary electron beam travels. For example, as in Figure 2A As in the illustrated embodiment, a beam splitter 222 can be provided to guide the secondary electron beam toward an off-axis detector. Figure 2A As shown, the beam splitter 222 can be configured to direct the secondary electron beam toward the electronic detection device 244 by a turning angle α.

[0059] In some embodiments of this disclosure, the PIN detector can be used as an in-lens detector in the decelerated objective SEM column of the EBI system 10. The PIN detector can be placed between the cathode used to generate the electron beam and the objective. The electron beam emitted from the cathode can be potentialized at -BE keV (typically about -10 kV). The electrons of the electron beam can be immediately accelerated and travel through the column. The column may be at ground potential. Therefore, the electrons can travel with kinetic energy of BE keV as they pass through the opening of the detector 144. The electrons pass through the pole piece of the objective (such as...) Figure 2B Electrons in the pole piece 132a of the objective lens assembly 132 can be rapidly decelerated to the landing energy LE keV because the surface potential of the wafer can be set to -(BE-LE) keV.

[0060] Figure 2C An example of a charged particle beam device 200C consistent with embodiments of the present disclosure is illustrated. The charged particle beam device 200C may be, for example... Figure 2A Charged particle beam device 200A or Figure 2B 200B. Emitted electrons 171 (including, for example, secondary electrons or backscattered electrons) are emitted from the wafer surface by an electron bombardment of the primary electron beam 105. As the primary electrons approach the detector spot 170, a decelerating electric field that slows them down can act as an accelerating electric field, propelling the emitted electrons backward toward the surface of the detector 144. For example, as... Figure 2CAs shown, due to the interaction between the detector spot 170 and the wafer 150, emitted electrons 171 may be generated, which return towards the detector 144. The emitted electrons 171, traveling from the wafer surface along the optical axis 105, can reach the surface of the detector 144, and their positional distribution depends primarily on the emission angle and energy of the emitted electrons, with a smaller influence from the precise emission position within the detector spot. For example, secondary electrons and backscattered electrons can be emitted from this region, and their angular distribution essentially follows Lambert's cosine law. That is, the distribution of emission angles may be substantially proportional to the cosine of the incident angle of the incoming electrons. This distribution is schematically illustrated by the length of the arrows in a close-up view of the detector spot 170.

[0061] Figure 2D An example of the distribution of electron arrival points on the detector surface is illustrated. For example, the diameter of detector 144 may be 10 mm or larger. In some embodiments, the diameter of the detector may be, for example, about 4 to 10 mm. Electrons 171a may land at different points on the surface of detector 144, but typically, in the absence of a deflection field, most may cluster around the central portion of detector 144. The shape, size, and location of the spatial distribution of arrival points on the detector surface can vary depending on the emission angle and energy of the emitted electrons. These emission angles and energies, in turn, may depend on the incident angle and energy of the incoming electrons from the primary electron beam 105. For example, when an ideal, aberration-free beam scans a flat region at the center of the normally incident field of view, the arrival points of the emitted electrons may form a substantially Gaussian distribution on detector 144. The distribution may differ for beams exhibiting aberrations. Therefore, under appropriate conditions, it may be possible to map the beam aberrations of the primary electron beam 105 to the final spatial distribution of emitted electrons arriving at the surface of detector 144.

[0062] As discussed above, emitted electrons can include, for example, secondary electrons or backscattered electrons. In some embodiments, the distribution may include, for example, between 60% and 85% secondary electrons and between 40% and 15% backscattered electrons. In some embodiments, it may be desirable to distinguish or filter out secondary electrons from other electrons, such that the detected distribution consists primarily of backscattered electrons. Backscattered electrons are caused by the elastic scattering of incoming electrons by atomic nuclei in the irradiated sample. These backscattered electrons can be emitted from the sample and have energies substantially the same as those of the incoming electrons from the primary electron beam. Because their energies can be correlated with the incoming energy, and their emission angles can be correlated with the electron incident angle using an approximate Lambertian distribution, the spatial distribution of backscattered electrons is particularly suitable for obtaining information about the incoming beam. Therefore, in some embodiments, the distribution may advantageously include up to, for example, 70%, 80%, 90%, 95%, 99%, or more backscattered electrons. For example, secondary electrons can be separated using, for example, a Wien filter or by biasing the sample to suppress the emission of secondary electrons. For example, a bias that slows down incoming electrons might reduce the generation of secondary electrons relative to backscattering, while causing all emitted electrons to be accelerated from the surface at higher energies. On the other hand, a bias that accelerates electrons toward the surface would attract emitted electrons back to the surface. Therefore, a bias could be applied that retains many lower-energy secondary electrons while allowing backscattered electrons to escape to the detector surface. Alternatively, energy differentiation could be used, for example, to filter out the detection signal arriving from secondary electrons.

[0063] Detector 144 can be positioned along optical axis 105. Primary electron beam can be configured to travel along optical axis 105. Therefore, detector 144 can include a hole 145 at its center, allowing the primary electron beam to pass through to reach wafer 150. Figures 2B to 2C An example of a detector 144 with an opening at its center is shown. However, some embodiments may use a detector positioned off-axis relative to the optical axis along which the primary electron beam travels. For example, as in Figure 2A As in the example shown, a beam splitter 222 can be provided to guide the emitted electron beam toward an off-axis detector. Figure 2A As shown, beam splitter 222 can be configured to direct the emitted electron beam toward electron detection device 244 by an angle α. Therefore, in some embodiments of this disclosure, a detector without a central opening can be provided.

[0064] Figure 2A Detector 244 or Figures 2B to 2DThe 144 may include sensing elements, such as diodes or diode-like elements, which can convert incident energy into a measurable signal. For example, sensing elements in a detector may include SPADs, APDs, scintillators, or PIN diodes. Throughout this disclosure, sensing elements may be represented as diodes, although sensing elements or other components may deviate from the ideal circuit behavior of electrical components such as diodes, resistors, and capacitors. In embodiments of this disclosure, a detector in a charged particle beam system may include a pixelated array of multiple sensing elements. In some embodiments, sensing elements may be configured for charged particle counting. Pixelated sensing elements for detectors that can be used for charged particle counting are discussed in U.S. Publication No. 2019 / 0378682, which is incorporated herein by reference in its entirety.

[0065] For ease of explanation and to avoid ambiguity, electrons are used as examples in some of the descriptions herein. However, it should be noted that any charged particle can be used in any embodiment of this disclosure, not just electrons. For example, a source in a charged particle beam tool can emit one or more charged particles, such as electrons, protons, ions, mesons, or any other particle carrying a charge. Furthermore, some embodiments of this disclosure may use photons instead of charged particles, such as visible light, UV, DUV, EUV, X-rays, or light in any other wavelength range. Therefore, while detectors in this disclosure may be disclosed relative to electron detection, some embodiments of this disclosure may involve the detection of other charged particles or photons.

[0066] Figures 3A to 3B An exemplary structure of a pixelated electronic detector consistent with embodiments of this disclosure is illustrated. Such as Figure 3A Detector 344a or Figure 3B Detectors such as 344b can be used as Figure 2A The detector 244 shown Figures 2B to 2D The 144 shown is provided. In Figure 3A In this configuration, detector 344a includes a sensor layer 301 and a signal processing layer 302. Sensor layer 301 may include a sensor die consisting of multiple sensing elements, including sensing elements 311, 312, 313, and 314. In some embodiments, multiple sensing elements may be provided in a sensing element array, each sensing element having a uniform size, shape, and arrangement.

[0067] Signal processing layer 302 may include multiple signal processing circuits, including circuits 321, 322, 323, and 324. The circuits may include interconnects (e.g., wiring paths) configured to communicatively couple or decouple sensing elements from each other. Each sensing element in sensor layer 301 may have a corresponding signal processing circuit in signal processing layer 302. Sensing elements and their corresponding circuits may be configured to operate independently. Figure 3A As shown, circuits 321, 322, 323 and 324 can be configured to be communicatively coupled to the outputs of sensing elements 311, 312, 313 and 314, respectively, as indicated by the four dashed lines between sensor layer 301 and signal processing layer 302.

[0068] In some embodiments, signal processing layer 302 may be configured as a single die on which multiple circuits are provided. Sensor layer 301 and signal processing layer 302 may be in direct contact. In some embodiments, components and functionalities of different layers may be combined or omitted. For example, signal processing layer 302 may be combined with sensor layer 301 as a single layer. Furthermore, circuitry for charged particle counting may be integrated at various points in the detector, such as in a separate readout layer of the detector or on a separate chip. Further details of the electronic counting circuitry system and alternative structures of sensor layer 301 and signal processing layer 302 can be found in International Publication WO 2022 / 008518, the entire contents of which are incorporated herein by reference.

[0069] like Figure 3B As shown, a detector 344b with a sensing element array 311 can be provided. The detector 344b can be, for example, a pixelated electronic detector. In some embodiments, the pixelated electronic detector can be a pixelated electron counting detector. The detector 344b may include a sensor layer 301 and a signal processing layer 302, such as... Figure 3A As seen in the image. The detector circuitry can be configured to separately detect the arrival of electrons individually from each sensing element. Detector 344b may include a plate 351 on which a plurality of sensing elements 311 are formed. Plate 351 may include an opening 345 to allow the primary electron beam to pass through plate 351.

[0070] When the individual sensing elements 311 of the detector become smaller compared to the spatial distribution of emitted electrons incident on the detector, the spatial distribution can be mapped on the detector surface with sufficient resolution to acquire useful information about the primary beam. For example, the individual sensing elements can be square or other shapes with side dimensions of, for example, 5, 10, 25, 50, 100, 200, or 300 µm. Sensing elements can be larger, for example, on the order of millimeters. A typical detector may include, for example, 100, 500, 1000, 5000, 10000, 50000, or 100000 or more sensing elements 311. Sensing elements can be configured for individual detection, or they can be coupled into groups. For example, when the pixel size of the individual sensing elements 311 is much smaller than the resolution required to map the spatial distribution on the detector 344b, the sensing elements can be grouped together so that their signals can be processed as a single element. This reduces the signal processing load while still achieving the objectives of this disclosure.

[0071] Embodiments of this disclosure utilize information acquired from individual sensing elements or groups of sensing elements to characterize the properties of the primary beam. Specifically, spatial distribution information of electron arrivals on the detector can be used to determine aberration values ​​of the primary beam. In some embodiments of this disclosure, the spatial distribution information may include, for example, the shape, size, centroid location, or intensity map of the electron arrival event distribution.

[0072] Figures 4A to 4F An example spatial distribution 475 of charged particles arriving at a charged particle detector 444 consistent with embodiments of this disclosure is shown. Detector 444 may correspond to, for example... Figures 2A to 2D Detector 144 or Figures 3A to 3B Detectors 344a or 344b. Detector 444 can be used in charged particle devices, such as... Figures 1 to 2C The arrival event can be, for example, the arrival of emitted electrons, and the charged particle detector can be an electron detector, such as a pixelated electron detector. This distribution can correspond to the backscattered electron distribution.

[0073] Figure 4A An example spatial distribution 475 of emitted electrons on detector 444 under ideal conditions consistent with embodiments of the present disclosure is depicted. For example, spatial distribution 475 could be a distribution of backscattered electrons produced by an aberration-free electron beam. The electron beam could be irradiated onto a flat, featureless portion of a test surface at the center of the field of view of the electron beam apparatus using it. Distribution 475 could be a substantially Gaussian distribution substantially centered on the detector surface, wherein substantially continuous intensity gradients of the electron arrival signal received by detector 444 are schematically illustrated as high, medium, and low intensity signals, respectively.

[0074] like Figure 4AAs illustrated, even an ideal electron beam may not produce a perfect spatial distribution 475 due to random variations in the emission angle, etc. However, as electron collection increases, the distribution typically converges toward the desired ideal shape. Typically, the number of imaging frames collected to form the spatial distribution 475 can vary depending on competing considerations, such as the desired resolution of the spatial distribution 475 and the desired measurement time. For example, while a high-resolution image of pattern features on a wafer might require integrating, for example, 10 to 100 imaging frames or more, in some embodiments, as few as one imaging frame may be used to measure the spatial distribution 475. In some embodiments, the spatial distribution 475 may include more than one imaging frame, such as 5, 10, 15, or 20 frames or more. For example, the spatial distribution 475 may include as many frames as are used to form an inspection image during the inspection process, or it may include more frames. As discussed further below, in some embodiments, the spatial distribution may be collected continuously or repeatedly while iterative feedback adjustments are performed to fine-tune the electron beam system in real time.

[0075] In some embodiments, the irradiated test surface can be a region of the sample to be inspected, such as the surface of a semiconductor wafer. Because emitted electrons may be blocked by adjacent pattern features, a test surface can be selected that is far from any pattern feature or other structure. For example, if the test surface portion is located near a raised line feature, electrons emitted from the test surface toward, for example, the sidewall of the line feature may be absorbed, while electrons emitted from the line feature may easily reach the detector surface. This will produce an asymmetry in the spatial distribution of the detector 444 that does not represent the beam characteristics. Therefore, in some embodiments, an empty, flat region (such as a scribe line, a large flat structure, or the peripheral region of the wafer) can be selected as the test surface. For example, the test surface may include a featureless portion of the sample that is at least as large as the field of view of the electron beam. In some embodiments, the test surface may include a relatively large flat pattern structure, such as a measurement target in a scribe line or elsewhere. In some embodiments, an in-die test surface can be selected within the die region of the wafer based on the determination that the region is sufficiently flat and empty, or that the region includes a sufficiently large flat in-die structure. For example, this determination may be based on, for example, a GDS file or other pattern data. Alternatively, the determination may be based on a previous scan of the same region or a previous scan of a corresponding region in a similar die region. In some embodiments, the test surface may be a printed flat area on the wafer surface. For example, the test surface may include, for instance, a square patch having a high-Z material deposition layer configured to generate a large number of backscattered electrons.

[0076] In some embodiments, the test surface may include a region on the support structure of the sample to be inspected, such as the area above relative to... Figure 2BThe measurement section 146 is discussed. Providing a test surface on the support structure can ensure a wide-area, highly flat surface to eliminate some unwanted factors that may affect the spatial distribution on detector 444, such as wafer warpage, high uncertainty, adjacent structures, or suboptimal surface materials.

[0077] In some embodiments, the test surface can be a plane located directly above the sample surface. For example, in some embodiments, the charged particle device can operate in a "mirror mode." In mirror mode, a precisely tuned potential can be applied to the sample surface to prevent incoming charged particles from actually impacting the surface, but instead reflect them back before reaching the surface. In this way, the incoming electrons are reflected in a manner reminiscent of light reflected from a mirror. The advantage of this mode is that it can eliminate the distribution noise inherent in the Lambertian distribution of the emitted particles.

[0078] However, the divergence of this reflected beam may be very close to that of the original incoming beam, making it difficult to achieve a distribution on the detector surface, as most of the beam would pass through the opening 445 through which the original incoming beam passes. Nevertheless, this arrangement may be advantageous for measuring, for example, off-axis information, such as the presence of distortion.

[0079] Figure 4B An example signal strength diagram 476 is depicted on detector 444 consistent with embodiments of this disclosure. Signal strength diagram 476 may correspond to Figure 4A The spatial distribution 475 can represent spatial distribution information of the spatial distribution 475. The intensity of the electron arrival signal received by each pixel 411 on detector 444 is schematically illustrated as high, medium, and low intensity signals, respectively. For example, the signal intensity at each pixel 411 can vary depending on the number or energy of the electrons arriving at that pixel. The signal intensity map 476 can represent the total intensity map of electron arrival events received at detector 444, or it can include, for example, energy-distinguishing signals representing only backscattered electrons.

[0080] In some embodiments, the signal strength map 476 can be analyzed to determine the geometric parameters of the spatial distribution 475. Figure 4CAn example boundary 477 is depicted in the signal intensity map 476 on detector 444 consistent with embodiments of this disclosure. Because the intensity gradient may decrease very slowly in the radial direction, and because a small number of electrons arriving at the signal may be scattered over a large area of ​​detector 444 due to false positives or random shot noise, the spatial distribution 475 may not have a precise geometric boundary. Therefore, boundary 477 can be determined to define, for example, the shape, size, centroid location, etc., of the spatial distribution 475. Further, by considering only those pixels 411 within boundary 477, boundary 477 can be used to simplify or optimize the analysis of intensity map 476. For example, the boundary can be drawn around substantially contiguous clusters of pixels with signal intensities above a predetermined threshold. Alternatively, boundary 477 can be drawn around a predetermined percentage of the total detected energy. For example, boundary 477 can be selected to surround, for example, 60%, 80%, 90%, 95%, 99%, or more of the energy detected at detector 444. In some embodiments, clustering algorithms or contour fitting algorithms can be used to define the boundary. In some embodiments, the boundary 477 may not be used, and the bundle properties may be determined by relying on the full signal strength map 476.

[0081] Spatial distribution information, such as signal intensity map 476 or boundary 477, can be analyzed, for example, by comparing it with one or more reference distributions, to determine whether aberrations exist. For example, the spatial distribution of electron arrivals at detector 444 may be related to the spatial distribution of the primary beam in the pupil plane of the charged particle beam system. Therefore, in some embodiments, the reference distribution may be related to the expected pupil plane distribution of the electron beam system or to model aberrations of the pupil plane distribution of the electron beam system.

[0082] The expected pupil plane distribution can also take into account other system parameters, such as, for example, lens setup downstream of the pupil plane, landing energy, field of view position, and other parameters of the charged particle beam system. The expected distribution can further consider other influences, such as, for example, the conditions under which the sample is irradiated, such as wafer morphology and surface material. For example, many fixed parameters associated with the charged particle beam system can affect the location and distribution of electrons arriving on the detector surface, such as, for example, electrode placement and setup, landing energy, and detector height. Deflection electrodes, focusing electrodes, or Wien filters can affect the location or shape of the electron distribution. The voltage on the deflector electrodes can affect the divergence of electrons as they move from the sample toward the detector. In individual detector branches (such as...) Figure 2AThe focusing electrode in (242) can also affect the position or shape. A Wien filter can also be used to counteract incident electrons from the detector center, for example, to minimize electron loss through the primary beam aperture. Furthermore, the geometric distribution of electron arrival may also increase with increasing landing energy. Additionally, for a given divergence value, increasing the detector height may result in greater electron diffusion. In some embodiments, comparing the spatial distribution of electron arrival with the expected pupil plane distribution can explain these factors.

[0083] In some embodiments, one or more reference distributions may correspond to a set of model aberrations. In this case, comparing a spatial distribution to one or more reference distributions may include fitting the spatial distribution to model aberrations or a weighted combination of model aberrations. In some embodiments, model aberrations may include a set of orthogonal or orthogonal functions, such as, for example, a set of functions orthogonal on disk. For example, in some embodiments, model aberrations may include, for example, a set of intensity distributions represented by Zernike polynomials.

[0084] Model aberrations can include one or more low-order aberrations, such as defocus, astigmatism, beam tilt, chromatic aberration, and beam shift. Model aberrations can also include higher-order aberrations, such as coma, pincushion or barrel distortion, spherical aberration, field curvature, and others. Typically, model aberrations can represent any typical aberration or combination of aberrations, such as one or more first-, second-, or third-order aberrations. Model aberrations can include off-axis and coaxial aberrations. For example, a test surface can be irradiated at an off-axis location in the field of view of an electron beam system to generate an off-axis signal intensity map 476, which can be compared with off-axis model aberrations.

[0085] In some embodiments, one or more reference distributions may correspond to a model or lookup table of experimental or simulated reference distributions. The reference distributions may include, for example, a reference signal intensity map or a reference boundary corresponding to the signal intensity map 476 and boundary 477 discussed above. For example, in some embodiments, the electron beam system may irradiate the test surface at a range of different exposure settings. These settings may include, for example, focusing settings, other lens settings, beam energy settings, field of view settings, etc. In some embodiments, multiple different exposure settings may be configured to produce multiple induced aberrations or combinations of induced aberrations. The resulting reference distributions can then be used for comparison in a subsequent aberration measurement process to determine aberrations within the electron beam system.

[0086] In some embodiments, a model can be constructed that correlates a spatial distribution in the detector plane with its corresponding pupil distribution. This can be achieved by directly measuring the pupil plane under multiple different exposure settings. For example, an electron beam system can be configured with a pupil detector located at or near the pupil plane, and the system can irradiate the pupil detector under multiple different exposure settings to generate multiple pupil distributions. The pupil detector can be configured, for example, to face a charged particle source and directly receive charged particles at the pupil surface to directly measure the pupil distribution. Then, with the pupil detector removed, the electron beam system can irradiate the test surface under the same multiple different exposure settings to obtain the relationship between each spatial distribution and its corresponding pupil distribution. The obtained relationship can then be used for comparison in a subsequent aberration measurement process to determine aberrations within the electron beam system.

[0087] Figure 4D An example model aberration 452 consistent with embodiments of this disclosure is depicted. Model aberration 452 may include a reference distribution 478 and may correspond to an ideal, aberration-free bundle. For example, when... Figures 4A to 4C When comparing the idealized spatial distribution information with a set of model aberrations or other reference distributions, Figures 4A to 4C The idealized spatial distribution information in [the model] can be closely identified using an aberration-free model 452. Therefore, it can be determined that, for [the model] used to generate [the desired spatial distribution]... Figure 4A The spatial distribution of the electron beam is 475, and the aberration is within acceptable limits.

[0088] Figure 4E Another example spatial distribution 475 of emitted electrons on detector 444, consistent with embodiments of this disclosure, is depicted. (As...) Figure 4F As seen in the image, the spatial distribution of 475 remains centered and is essentially symmetrical, similar to... Figure 4A The ideal version. However, the distribution is larger and more diffuse, with smaller high-intensity areas. This distribution may be caused by focusing errors, where the probe spot on the test surface is larger and more diffuse due to improper focusing. Therefore, Figure 4E The spatial distribution of defocus can be identified using a reference distribution corresponding to the focus error, and appropriate focus corrections can be determined and applied.

[0089] Figure 4F Another example spatial distribution 475 of emitted electrons on detector 444, consistent with embodiments of this disclosure, is depicted. Here, spatial distribution 475 may exhibit further aberrations, resulting in lateral shifts and skewed shapes on the surface of detector 444. Spatial distribution information (such as intensity maps 476 or boundaries 477 discussed above) can be compared with a set of reference distributions. For example, Figure 4FThe spatial distribution of shifts and skews can be identified by a weighted combination of reference distributions corresponding to, for example, astigmatism and beam tilt. Therefore, appropriate aberration corrections can be determined and applied.

[0090] While the above embodiments are discussed in relation to high-resolution pixelated detectors, the embodiments disclosed herein are not limited thereto. For example, in some embodiments, limited information may be obtained from a low-resolution segmented detector. Figure 5 Multiple spatial distributions of electron arrival events on multiple segmented detectors consistent with embodiments of the present disclosure are schematically illustrated. Here, three different types of segmented detectors are depicted under two different representative distributions 575. The representative distribution 575 may correspond to, for example... Figure 4E and 4F The symmetric and asymmetric spatial distributions are illustrated to illustrate the capabilities and limitations of each segmented detector. For example, a two-segment detector 580 can be configured to discern low-resolution information about spatial asymmetry, but may fail to identify symmetry errors such as defocus. A similar problem may arise with a four-quadrant segmented detector 581, where limited asymmetry information can be obtained in two dimensions, but symmetry errors such as defocus may still remain unidentified. On the other hand, a segmented loop detector 582 may present the opposite problem. For example, in some embodiments, defocus can be roughly measured by comparing the relative signal strengths from multiple concentric loop segments. However, beam shift, distortion, and other asymmetric errors may not be identified. Therefore, while some embodiments may use simpler detector systems (such as...) Figure 5 The segmented detectors (580 to 582) utilize spatial distribution information to obtain bundle information, but use, for example, based on... Figures 4A to 4F The pixelated electronic detector can more accurately determine beam aberrations.

[0091] Figures 6A to 6C Flowcharts illustrating example methods 600, 650, and 660 for determining aberrations in a charged particle beam using a charged particle detector, consistent with embodiments of this disclosure, are shown. For example, Figure 6A Method 600 may include methods for measuring aberrations, while Figures 6B to 6C Methods 650 and 660 may include additional steps for obtaining reference information, such as those in method 600. The charged particle detector may be part of a charged particle beam apparatus. For example, a charged particle beam detector may be a pixelated electron detector in a SEM used for scanning inspection of samples such as semiconductor wafers. The detector may be, for example... Figure 2A Detector 244 Figures 2B to 2D Detector 144 Figure 3A Detector 344a Figure 3B Detector 344b Figures 4A to 4F Detector 444 or Figure 5 The detectors are 580 to 582.

[0092] Methods 600, 650, and 660 can be executed by a processor and memory of a controller configured to control a charged particle beam apparatus to perform the method. Methods 650 and 660 can be performed prior to aberration measurements. The method can be performed periodically or on demand, for example, during high-volume production, relative to the actual aberration measurement of method 600. For example, the method can be performed at regular time intervals, such as every 30 minutes, or after the beam has been irradiated for a predetermined exposure time or dose during an inspection process. Further, the method can be performed per wafer, or after a predetermined number of wafers have been inspected, or at each die region, or after a predetermined number of die regions have been inspected. Further, the method can be performed on demand, such as when, for example, image analysis determines that the aberration has exceeded a predetermined threshold.

[0093] Finally, during the charged particle beam inspection process, method 600 can be performed "in real time" at any of these intervals. For example, the detector can be configured to selectively retain spatial distribution information from one or more imaging frames from a predetermined test surface. Thus, while most imaging frames may not retain spatial distribution information (because the processing load of such capture could be too heavy), the detector can be configured to retain this information when the beam scan is selected as the location of the test surface. This allows for more frequent aberration monitoring without significantly impairing the throughput of the charged particle beam inspection or imposing any significant additional burden on the data processing load.

[0094] exist Figure 6A In step 610, the controller can control the charged particle beam device to irradiate the test surface with a charged particle beam. The test surface may include, for example, a substantially flat, featureless region of the sample being examined. Alternatively, the test surface may include, for example, a flat measurement section located on a sample support platform.

[0095] In step 620, the controller may obtain spatial distribution information of the arrived charged particles detected on the surface of the charged particle detector. For example, the spatial distribution information may include the arrival locations of multiple emitted electrons on the detector surface. The spatial distribution information may primarily include backscattered electrons, or it may include, for example, a combination of secondary electrons and backscattered electrons. In some embodiments, the spatial distribution information may include a signal intensity map corresponding to the signal intensity value at each detected pixel on the detector. In some embodiments, the spatial distribution information may include a boundary determined based on the signal intensity map. The boundary may be used to define the geometric properties of the spatial distribution on the detector, such as size, shape, or location.

[0096] In step 630, the controller can use the spatial distribution information to determine the aberrations of the charged particle beam. For example, the aberrations can be determined by comparing the spatial distribution information with one or more reference distributions. The reference distributions can be based on, for example, the reference pupil plane distribution of the charged particle beam system. For example, comparing the spatial distribution with one or more reference distributions can include fitting the spatial distribution to model aberrations or a weighted combination of model aberrations. Model aberrations can include, for example, a set of intensity distributions represented by Zernike polynomials or a similar representative set of model aberrations. Model aberrations can include one or more of the following: defocus, astigmatism, beam tilt, beam shift, coma, pincushion or barrel distortion, spherical aberration, chromatic aberration, diffraction error, field curvature, and others. In some embodiments, the spatial distribution information can be decomposed into a weighted combination of model aberrations.

[0097] In step 640, the controller may determine appropriate adjustments to the charged particle beam system based on the determined aberrations. In some embodiments, the controller may also perform the adjustments, in some cases in conjunction with the operator of the charged particle beam device.

[0098] Using method 600, beam aberration measurements can be performed faster and more accurately than existing methods. Measurements can be better integrated into inspection operations to reduce downtime. Furthermore, measurements can be performed using the actual focus values ​​and other lens settings employed during actual inspection, rather than performing “defocus” inspections at a range of different focus values. This allows for observation of beam properties under real-world conditions, leading to a better understanding of potential aberrations.

[0099] Figure 6B A flowchart of an example method 650 for obtaining reference information to be used in an aberration measurement method for a charged particle device, consistent with embodiments of this disclosure, is illustrated. Method 650 can be used to determine reference information for, for example... Figure 6A Method 600. For example, in step 630, which determines aberrations based on spatial distribution information, reference information may be applied. The charged particle beam device used in method 650 may be the same charged particle beam device used in method 600, or it may be a different charged particle beam device. For example, the specific detector used to obtain the reference information may be referred to as a reference detector, but it should be understood that the reference detector may be the same as or different from the detector used in method 600.

[0100] In step 651, the controller can control the charged particle beam device to irradiate the test surface with a charged particle beam under multiple different exposure conditions. These multiple different exposure conditions can include a series of exposure settings, such as focusing settings, lens settings, beam energy settings, field of view settings, etc. The multiple different exposure conditions can be designed to capture the operating range of such settings or a range greater than the expected operating range of such settings. The multiple different exposure conditions can include a set of induced aberrations configured to simulate aberrations expected to be encountered during aberration measurements.

[0101] In step 652, the controller may obtain spatial distribution information on the reference detector for each of a plurality of different exposure settings in a manner similar to step 620 of method 600. In step 653, the spatial distribution information may be evaluated based on known values ​​for the different exposure settings to construct a model that describes the spatial distribution information as a function of the different exposure settings. In some embodiments, the model may include a mathematical representation of the spatial distribution as a function of bundle parameters induced at the plurality of different exposure settings. In some embodiments, the model may include a lookup table relating the measured spatial distribution information to the bundle parameters induced at the plurality of different exposure settings.

[0102] In step 654, the controller can use the model during the aberration measurement process to correlate the spatial distribution information of the measurements with one or more aberration values ​​based on the experimentally derived relationship obtained in step 653. For example, step 630 of method 600 may include step 654 of method 650.

[0103] Figure 6C A further flowchart of an example method 660 for obtaining reference information to be used in an aberration measurement method for a charged particle device, consistent with embodiments of this disclosure, is illustrated. Method 660 can be used to determine reference information for, for example... Figure 6A Method 600. For example, in step 630, which determines aberrations based on spatial distribution information, reference information can be applied.

[0104] In step 661, the controller can control the charged particle beam device to irradiate the pupil detector with charged particle beams under multiple different exposure conditions. These multiple different exposure conditions can correspond to the multiple different exposure settings discussed above with respect to method 650.

[0105] In step 662, the controller can obtain first spatial distribution information on the pupil detector for each of a plurality of different exposure settings in a manner similar to step 620 of method 600. However, unlike existing methods, the pupil detector can be located at or near the pupil plane of the charged particle beam device to directly measure the pupil distribution of the charged particle beam. This distribution can be obtained without any downstream influences (such as other lenses and electrodes) and without the influence of the Lambertian emission distribution from the test surface.

[0106] In step 663, with the pupil detector removed, for each of the plurality of different exposure settings used in step 661 to irradiate the pupil detector, the controller can control the charged particle beam device to irradiate the test surface in a manner similar to step 651 of method 650. In step 664, the controller can obtain second spatial distribution information from the charged particle reference detector in a manner similar to step 652 of method 650. Therefore, the controller can obtain a corresponding set of first spatial distribution information and second spatial distribution information for each of the plurality of different exposure settings, wherein the first spatial distribution information is obtained at the pupil plane, and the spatial distribution information is obtained at the charged particle beam inspection / reference detector.

[0107] In step 665, the controller may compare the first spatial distribution information and the second spatial distribution information to construct a model describing the relationship between the pupil distribution on the charged particle detector during the inspection process and the final spatial distribution. In some embodiments, the model may include a mathematical representation of the spatial distribution as a function of the pupil distribution induced under multiple different exposure settings. In some embodiments, the model may include a lookup table that correlates the measured spatial distribution information of the inspection detector with the pupil distribution induced under multiple different exposure settings.

[0108] In step 666, the controller may use the model during the aberration measurement process to correlate the spatial distribution information of the measurements with one or more aberration values ​​based on the experimentally derived relationship obtained in step 665. For example, step 630 of method 600 may include step 666 of method 660.

[0109] Figure 7 The illustration shows a flowchart of an example method 700 for real-time correction of aberrations in a charged particle beam using a charged particle detector, consistent with embodiments of the present disclosure. Method 700 may include... Figure 6A This is a special case of method 600, serving as an iterative feedback correction. For example, steps 710 to 730 can correspond to steps 610 to 630 of method 600. Therefore, a detailed description is omitted here.

[0110] In step 740, the controller can determine whether the aberration is below a predetermined threshold. If so, the method terminates in step 760. However, if the aberration is not below the predetermined threshold, the method can continue to step 750, where the controller can perform incremental adjustments to reduce the aberration. After performing the correction, or while still performing the correction, the controller can repeat steps 710 through 740 to evaluate the modified spatial distribution information and determine whether the aberration has been reduced below the desired threshold. This iterative cycle of monitoring and performing incremental adjustments can continue until all aberration values ​​are below the threshold.

[0111] Method 700 can be advantageously performed in real time during inspection processes, such as between wafers, between die areas, etc., to accurately determine whether all aberrations are at the desired level. This advantage is not available using conventional defocus measurements.

[0112] A non-transitory computer-readable medium may be provided, the storage of which is used for controllers (e.g. Figure 1 Instructions of the processor of the controller (109) in the present disclosure are used to determine aberrations using embodiments of the present disclosure. For example, instructions stored in a non-transitory computer-readable medium may be executed by the circuitry of the controller to perform methods 600, 650, 660, or 700 in part or in whole. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tape or any other magnetic data storage media, compact disc read-only memory (CD-ROM), any other optical data storage media, any physical medium with a perforated pattern, random access memory (ROM), 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), cache, registers, any other memory chip or cassette tape and its networking version.

[0113] The embodiments may be further described using the following terms: 1. A non-transitory computer-readable medium storing an instruction set executable by at least one processor of a device to cause the device to perform operations, comprising: The surface is irradiated with charged particle beams using a charged particle beam system; Obtain spatial distribution information of charged particles detected by the charged particle detector; Determining the aberration values ​​of a charged particle beam based on spatial distribution information; and Adjustments are performed on the charged particle beam system based on the determined aberration values. 2. A non-transitory computer-readable medium according to Clause 1, wherein spatial distribution information includes an intensity map of charged particle arrivals on a detector. 3. A non-transitory computer-readable medium pursuant to Clause 2, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 4. A non-transitory computer-readable medium pursuant to Clause 3, wherein the boundaries are defined based on an intensity threshold. 5. A non-transitory computer-readable medium pursuant to Clause 3, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 6. A non-transitory computer-readable medium according to Clause 5, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 7. A non-transitory computer-readable medium pursuant to Clause 3, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 8. A non-transitory computer-readable medium pursuant to Clause 1, wherein the spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 9. A non-transitory computer-readable medium according to Clause 1, wherein determining the aberration values ​​of a charged particle beam based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 10. A non-transitory computer-readable medium pursuant to Clause 9, wherein a plurality of reference distributions comprise a set of model aberrations. 11. A non-transitory computer-readable medium pursuant to Clause 10, wherein the model aberrations are based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 12. A non-transitory computer-readable medium pursuant to Clause 10, wherein the charged particle detector is a reference charged particle detector. 13. A non-transitory computer-readable medium pursuant to Clause 10, wherein the model aberration is based on multiple measurements on the pupil charged particle detector at multiple different exposure settings. 14. A non-transitory computer-readable medium pursuant to Clause 10, wherein model aberrations are based on a set of orthogonal functions on a disk. 15. A non-transitory computer-readable medium according to Clause 1, wherein the charged particle detector includes a pixelated charged particle detector having an array of sensing elements. 16. A non-transitory computer-readable medium pursuant to Clause 15, wherein the pixelated charged particle detector comprises at least 100 sensing elements configured to detect independent signal strength values. 17. A non-transitory computer-readable medium pursuant to Clause 1, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Spatial distribution information includes asymmetric parameters. 18. A non-transitory computer-readable medium pursuant to Clause 1, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Spatial distribution information includes focusing parameters. 19. A non-transitory computer-readable medium pursuant to Clause 1, wherein aberration values ​​include one of first-order aberrations, second-order aberrations, or third-order aberrations. 20. A non-transitory computer-readable medium pursuant to Clause 1, wherein aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 21. A non-transitory computer-readable medium pursuant to Clause 1, wherein the surface includes the surface of the sample to be inspected. 22. A non-transitory computer-readable medium pursuant to Clause 21, wherein the surface of the sample to be inspected includes one of a peripheral unpatterned area, scribe lines, measurement marks, or a featureless inner region of the die. 23. A non-transitory computer-readable medium pursuant to Clause 1, wherein the surface includes the surface of a sample platform configured to support a sample to be examined. 24. A non-transitory computer-readable medium according to Clause 1, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 25. A non-transitory computer-readable medium pursuant to Clause 1, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 26. A non-transitory computer-readable medium pursuant to Clause 1, wherein the arrival of detected charged particles includes at least 70% backscattered electrons. 27. A non-transitory computer-readable medium pursuant to Clause 1, wherein the operation further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another aberration value of the charged particle beam based on another spatial distribution information; and Another adjustment is performed on the charged particle beam system based on another aberration. 28. A charged particle beam device, comprising: The charged particle beam source is configured to generate a primary charged particle beam; A charged particle optical system is configured to guide a primary charged particle beam to a surface. The controller, including one or more processors and configured to cause the charged particle beam device to perform operations, includes: Obtain spatial distribution information of charged particles detected by the charged particle detector; Determining the aberration values ​​of the charged particle beam based on spatial distribution information, and Adjustments are performed on the charged particle beam system based on the determined aberration values. 29. A charged particle beam device according to Clause 28, wherein spatial distribution information includes an intensity map of charged particle arrivals on a detector. 30. A charged particle beam device according to Clause 29, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 31. A charged particle beam device according to Clause 30, wherein the boundary is defined based on an intensity threshold. 32. A charged particle beam device according to Clause 30, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 33. A charged particle beam device according to Clause 32, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 34. A charged particle beam device according to Clause 30, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 35. A charged particle beam apparatus pursuant to Clause 28, wherein the spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 36. A charged particle beam apparatus according to Clause 28, wherein determining the aberration values ​​of the charged particle beam based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 37. A charged particle beam device according to Clause 36, wherein a plurality of reference distributions include a set of model aberrations. 38. A charged particle beam apparatus according to Clause 37, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 39. A charged particle beam apparatus pursuant to Clause 37, wherein the charged particle detector is a reference charged particle detector. 40. A charged particle beam apparatus according to Clause 37, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 41. A charged particle beam apparatus according to Clause 37, wherein the model aberrations are based on a set of orthogonal functions on a disk. 42. A charged particle beam apparatus according to Clause 28, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 43. A charged particle beam apparatus according to Clause 15, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 44. A charged particle beam device according to Clause 28, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Spatial distribution information includes asymmetric parameters. 45. A charged particle beam device according to Clause 28, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Spatial distribution information includes focusing parameters. 46. ​​A charged particle beam apparatus according to Clause 28, wherein the aberration values ​​include one of first-order aberration, second-order aberration, or third-order aberration. 47. A charged particle beam apparatus pursuant to Clause 28, wherein the aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 48. A charged particle beam apparatus according to Clause 28, wherein the surface includes the surface of the sample to be inspected. 49. A charged particle beam apparatus pursuant to Clause 48, wherein the surface of the sample to be inspected includes one of an unpatterned peripheral region, scribing, measurement markings, or a featureless inner region of the die. 50. A charged particle beam apparatus according to Clause 28, wherein the surface includes a sample platform configured to support a sample to be examined. 51. A charged particle beam device according to Clause 28, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 52. A charged particle beam device according to Clause 28, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 53. A charged particle beam device according to Clause 28, wherein the detected charged particle arrivals include at least 70% backscattered electron arrivals. 54. The charged particle beam device pursuant to Clause 28, wherein operation further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another aberration value of the charged particle beam based on another spatial distribution information; and Another adjustment is performed on the charged particle beam system based on another aberration. 55. A method for using charged particle beams, comprising: The surface is irradiated with charged particle beams using a charged particle beam system; Obtain spatial distribution information of charged particles detected by the charged particle detector; Determining the aberration values ​​of a charged particle beam based on spatial distribution information; and Adjustments are performed on the charged particle beam system based on the determined aberration values. 56. The charged particle beam method according to Clause 55, wherein the spatial distribution information includes an intensity map of charged particle arrivals on the detector. 57. The charged particle beam method according to Clause 56, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 58. The charged particle beam method according to Clause 57, wherein the boundary is defined based on an intensity threshold. 59. The charged particle beam method according to Clause 57, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 60. The charged particle beam method according to Clause 59, wherein the threshold percentage is greater than 90% of the energy detected on the detector and less than 100% of the energy detected on the detector. 61. The charged particle beam method according to Clause 57, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 62. The charged particle beam method according to Clause 55, wherein the spatial distribution information includes one of the shape, size or centroid location of the distribution of charged particles arriving at the detector. 63. The charged particle beam method according to Clause 55, wherein determining the aberration values ​​of the charged particle beam based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 64. The charged particle beam method according to Clause 63, wherein multiple reference distributions comprise a set of model aberrations. 65. The charged particle beam method according to Clause 64, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 66. The charged particle beam method according to Clause 64, wherein the charged particle detector is a reference charged particle detector. 67. The charged particle beam method according to Clause 64, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 68. The charged particle beam method according to Clause 64, wherein the model aberrations are based on a set of orthogonal functions on a disk. 69. The charged particle beam method according to Clause 55, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 70. The charged particle beam method according to Clause 69, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 71. The charged particle beam method according to Clause 55, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Spatial distribution information includes asymmetric parameters. 72. The charged particle beam method according to Clause 55, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Spatial distribution information includes focusing parameters. 73. The charged particle beam method according to Clause 55, wherein the aberration values ​​include one of first-order aberrations, second-order aberrations, or third-order aberrations. 74. The charged particle beam method according to Clause 55, wherein the aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 75. The charged particle beam method according to Clause 55, wherein the surface includes the surface of the sample to be inspected. 76. The charged particle beam method according to Clause 75, wherein the surface of the sample to be inspected includes one of the peripheral unpatterned area, scribing, measurement markings, or a featureless inner region of the die. 77. The charged particle beam method according to Clause 55, wherein the surface includes a surface configured to support a sample platform to be examined. 78. The charged particle beam method according to Clause 55, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 79. The charged particle beam method according to Clause 55, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 80. The charged particle beam method according to Clause 55, wherein the detected charged particle arrivals include at least 70% backscattered electron arrivals. 81. The charged particle beam method pursuant to Clause 55 further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another aberration value of the charged particle beam based on another spatial distribution information; and Another adjustment is performed on the charged particle beam system based on another aberration. 82. A non-transitory computer-readable medium storing an instruction set executable by at least one processor of a device to cause the device to perform operations, comprising: A charged particle beam system is used to irradiate a surface with a charged particle beam, causing charged particles to be emitted from the surface. Charged particles are detected on the charged particle detector of a charged particle beam system to generate a charged particle detection signal; The charged particle detection signal is compared with a reference charged particle detection signal; The aberration values ​​of the charged particle beam are determined by comparison; Adjustments are performed on the charged particle beam system based on determined aberration values; and Use a detector to examine the sample. 83. A non-transitory computer-readable medium pursuant to Clause 82, wherein the detection signal includes information on the spatial distribution of charged particles arriving as detected by a charged particle detector. 84. A non-transitory computer-readable medium pursuant to Clause 83, wherein spatial distribution information includes an intensity map of charged particle arrivals on a detector. 85. A non-transitory computer-readable medium pursuant to Clause 84, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 86. A non-transitory computer-readable medium pursuant to Clause 85, wherein the boundaries are defined based on an intensity threshold. 87. A non-transitory computer-readable medium pursuant to Clause 85, wherein the boundary is defined as a threshold percentage of the energy detected on the detector. 88. A non-transitory computer-readable medium pursuant to Clause 87, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 89. A non-transitory computer-readable medium pursuant to Clause 85, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 90. A non-transitory computer-readable medium pursuant to Clause 83, wherein spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 91. A non-transitory computer-readable medium pursuant to Clause 83, wherein determining the aberration values ​​of a charged particle beam based on comparison includes comparing spatial distribution information with multiple reference distributions. 92. A non-transitory computer-readable medium pursuant to Clause 91, wherein a plurality of reference distributions comprise a set of model aberrations. 93. A non-transitory computer-readable medium pursuant to Clause 92, wherein model aberrations are based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 94. A non-transitory computer-readable medium pursuant to Clause 92, wherein the charged particle detector is a reference charged particle detector. 95. A non-transitory computer-readable medium pursuant to Clause 92, wherein model aberrations are based on multiple measurements on a pupil charged particle detector at multiple different exposure settings. 96. A non-transitory computer-readable medium pursuant to Clause 92, wherein model aberrations are based on a set of orthogonal functions on a disk. 97. A non-transitory computer-readable medium pursuant to Clause 82, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 98. A non-transitory computer-readable medium pursuant to Clause 97, wherein a pixelated charged particle detector comprises at least 100 sensing elements configured to detect independent signal strength values. 99. A non-transitory computer-readable medium pursuant to Clause 82, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and The charged particle detection signal includes asymmetry parameters in at least four segments. 100. A non-transitory computer-readable medium pursuant to Clause 82, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and The charged particle detection signal includes focusing parameters. 101. A non-transitory computer-readable medium pursuant to Clause 82, wherein aberration values ​​include one of first-order aberrations, second-order aberrations, or third-order aberrations. 102. A non-transitory computer-readable medium pursuant to Clause 82, wherein aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 103. A non-transitory computer-readable medium pursuant to Clause 82, wherein the surface includes the surface of the sample to be inspected. 104. A non-transitory computer-readable medium pursuant to Clause 103, wherein the surface of the sample to be inspected includes one of a peripheral unpatterned area, scribing, measurement markings, or a featureless inner region of the die. 105. A non-transitory computer-readable medium pursuant to Clause 82, wherein the surface includes a surface configured to support a sample platform for examination. 106. A non-transitory computer-readable medium pursuant to Clause 82, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 107. A non-transitory computer-readable medium pursuant to Clause 82, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 108. A non-transitory computer-readable medium pursuant to Clause 82, wherein the arrival of detected charged particles includes at least 70% backscattered electrons. 109. A non-transitory computer-readable medium pursuant to Clause 82, wherein the operation further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; Detect other charged particles on the charged particle detector to generate another charged particle detection signal; Determine another aberration value of the charged particle beam based on another charged particle detection signal; and Another adjustment is performed on the charged particle beam system based on another aberration. 110. A charged particle beam device, comprising: The charged particle beam source is configured to generate a primary charged particle beam; A charged particle optical system is configured to guide a primary charged particle beam to a surface. The controller, including one or more processors and configured to cause the charged particle beam device to perform operations, includes: Irradiate the surface with a beam of charged particles to cause charged particles to be emitted from the surface; Charged particles are detected on the charged particle detector of a charged particle beam system to generate a charged particle detection signal; The charged particle detection signal is compared with a reference charged particle detection signal; The aberration values ​​of the charged particle beam are determined by comparison; Adjustments are performed on the charged particle beam system based on determined aberration values; and Use a detector to examine the sample. 111. A charged particle beam apparatus according to Clause 110, wherein the detection signal includes information on the spatial distribution of charged particles arriving as detected by a charged particle detector. 112. A charged particle beam device according to Clause 111, wherein spatial distribution information includes an intensity map of charged particles arriving at the detector. 113. A charged particle beam device according to Clause 112, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 114. A charged particle beam device pursuant to Clause 113, wherein the boundary is defined based on an intensity threshold. 115. A charged particle beam device according to Clause 113, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 116. A charged particle beam device according to Clause 115, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 117. A charged particle beam device according to Clause 113, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 118. A charged particle beam apparatus pursuant to Clause 111, wherein the spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 119. A charged particle beam apparatus according to Clause 111, wherein determining the aberration value of the charged particle beam based on comparison includes comparing spatial distribution information with multiple reference distributions. 120. A charged particle beam device according to Clause 119, wherein multiple reference distributions include a set of model aberrations. 121. A charged particle beam apparatus according to Clause 120, wherein model aberrations are based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 122. A charged particle beam apparatus according to Clause 120, wherein the charged particle detector is a reference charged particle detector. 123. A charged particle beam apparatus according to Clause 120, wherein model aberrations are based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 124. A charged particle beam apparatus according to Clause 120, wherein model aberrations are based on a set of orthogonal functions on a disk. 125. A charged particle beam apparatus according to Clause 110, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 126. A charged particle beam apparatus according to Clause 125, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 127. A charged particle beam device according to Clause 110, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and The charged particle detection signal includes asymmetry parameters in at least four segments. 128. A charged particle beam device according to Clause 110, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and The charged particle detection signal includes focusing parameters. 129. A charged particle beam apparatus pursuant to Clause 110, wherein the aberration values ​​include one of first-order aberration, second-order aberration, or third-order aberration. 130. A charged particle beam apparatus pursuant to Clause 110, wherein the aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 131. A charged particle beam apparatus according to Clause 110, wherein the surface includes the surface of the sample to be inspected. 132. A charged particle beam apparatus pursuant to Clause 131, wherein the surface of the sample to be inspected includes one of an unpatterned peripheral region, scribe lines, measurement markings, or a featureless inner region of the die. 133. A charged particle beam apparatus according to Clause 110, wherein the surface includes a sample platform configured to support a sample to be examined. 134. A charged particle beam device according to Clause 110, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 135. A charged particle beam device pursuant to Clause 110, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 136. A charged particle beam device according to Clause 110, wherein the detected charged particle arrival includes at least 70% backscattered electron arrival. 137. The charged particle beam device pursuant to Clause 110, wherein operation further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; Detect other charged particles on the charged particle detector to generate another charged particle detection signal; Determine another aberration value of the charged particle beam based on another charged particle detection signal; and Another adjustment is performed on the charged particle beam system based on another aberration. 138. A charged particle beam method, comprising: A charged particle beam system is used to irradiate a surface with a charged particle beam, causing charged particles to be emitted from the surface. Charged particles are detected on the charged particle detector of a charged particle beam system to generate a charged particle detection signal; The charged particle detection signal is compared with a reference charged particle detection signal; The aberration values ​​of the charged particle beam are determined by comparison; Adjustments are performed on the charged particle beam system based on determined aberration values; and Use a detector to examine the sample. 139. The charged particle beam method according to Clause 138, wherein the detection signal includes information on the spatial distribution of the arrival of charged particles detected on the charged particle detector. 140. The charged particle beam method according to Clause 139, wherein the spatial distribution information includes an intensity map of charged particle arrivals on the detector. 141. The charged particle beam method according to Clause 140, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 142. The charged particle beam method according to Clause 141, wherein the boundary is defined based on an intensity threshold. 143. The charged particle beam method according to Clause 141, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 144. The charged particle beam method according to Clause 143, wherein the threshold percentage is greater than 90% of the energy detected on the detector and less than 100% of the energy detected on the detector. 145. The charged particle beam method according to clause 141, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 146. The charged particle beam method according to Clause 139, wherein the spatial distribution information includes one of the shape, size or centroid location of the distribution of charged particles arriving at the detector. 147. The charged particle beam method according to Clause 139, wherein determining the aberration value of the charged particle beam based on comparison includes comparing spatial distribution information with multiple reference distributions. 148. The charged particle beam method according to Clause 147, wherein multiple reference distributions comprise a set of model aberrations. 149. The charged particle beam method according to Clause 148, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 150. The charged particle beam method according to Clause 148, wherein the charged particle detector is a reference charged particle detector. 151. The charged particle beam method according to Clause 148, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 152. The charged particle beam method according to Clause 148, wherein the model aberrations are based on a set of orthogonal functions on a disk. 153. The charged particle beam method according to Clause 138, wherein the charged particle detector includes a pixelated charged particle detector having an array of sensing elements. 154. The charged particle beam method according to Clause 153, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 155. The charged particle beam method according to Clause 138, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and The charged particle detection signal includes asymmetry parameters in at least four segments. 156. The charged particle beam method according to Clause 138, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and The charged particle detection signal includes focusing parameters. 157. The charged particle beam method according to Clause 138, wherein the aberration values ​​include one of first-order aberration, second-order aberration, or third-order aberration. 158. The charged particle beam method according to Clause 138, wherein the aberration values ​​include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 159. The charged particle beam method according to Clause 138, wherein the surface includes the surface of the sample to be inspected. 160. The charged particle beam method according to Clause 159, wherein the surface of the sample to be inspected includes one of the peripheral unpatterned area, scribing, measurement markings, or a featureless inner region of the die. 161. The charged particle beam method according to Clause 138, wherein the surface includes a surface configured to support a sample platform for the sample to be examined. 162. The charged particle beam method according to Clause 138, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 163. The charged particle beam method according to Clause 138, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 164. The charged particle beam method according to Clause 138, wherein the detected charged particle arrivals include at least 70% backscattered electron arrivals. 165. The charged particle beam method according to Clause 138 further includes: After the adjustment is performed, the aberration value is determined to be no less than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; Detect other charged particles on the charged particle detector to generate another charged particle detection signal; Determine another aberration value of the charged particle beam based on another charged particle detection signal; and Another adjustment is performed on the charged particle beam system based on another aberration. 166. A non-transitory computer-readable medium storing an instruction set executable by at least one processor of a device to cause the device to perform operations, comprising: A charged particle beam system is used to irradiate a surface with a charged particle beam, causing charged particles to be emitted from the surface. To obtain spatial distribution information of charged particles arriving at the charged particle detector of the charged particle beam system; The parameter values ​​of the pupil plane distribution of the charged particle beam are determined based on spatial distribution information; Adjustments are performed on the charged particle beam system based on determined parameter values; and Use a detector to examine the sample. 167. A non-transitory computer-readable medium pursuant to Clause 166, wherein spatial distribution information includes an intensity map of charged particle arrivals on a detector. 168. A non-transitory computer-readable medium pursuant to Clause 167, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 169. A non-transitory computer-readable medium pursuant to Clause 168, wherein the boundaries are defined based on an intensity threshold. 170. A nontransitory computer-readable medium pursuant to Clause 168, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 171. A non-transitory computer-readable medium pursuant to Clause 170, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 172. A non-transitory computer-readable medium pursuant to Clause 168, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 173. A non-transitory computer-readable medium pursuant to Clause 166, wherein spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 174. A non-transitory computer-readable medium pursuant to Clause 166, wherein determining parameter values ​​for the pupil plane distribution based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 175. A non-transitory computer-readable medium pursuant to Clause 174, wherein a plurality of reference distributions comprise a set of model aberrations. 176. A non-transitory computer-readable medium pursuant to Clause 175, wherein model aberrations are based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 177. A non-transitory computer-readable medium pursuant to Clause 175, wherein the charged particle detector is a reference charged particle detector. 178. A non-transitory computer-readable medium pursuant to Clause 175, wherein model aberrations are based on multiple measurements on a pupil charged particle detector at multiple different exposure settings. 179. A non-transitory computer-readable medium pursuant to Clause 175, wherein model aberrations are based on a set of orthogonal functions on a disk. 180. A non-transitory computer-readable medium pursuant to Clause 166, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 181. A non-transitory computer-readable medium pursuant to Clause 180, wherein a pixelated charged particle detector comprises at least 100 sensing elements configured to detect independent signal strength values. 182. A non-transitory computer-readable medium pursuant to Clause 166, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the asymmetry parameters in at least four segments. 183. A non-transitory computer-readable medium pursuant to Clause 166, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the focusing parameters. 184. A non-transitory computer-readable medium pursuant to Clause 166, wherein the parameters of the pupil plane distribution of a charged particle beam include one of first-order aberrations, second-order aberrations, or third-order aberrations. 185. A non-transitory computer-readable medium pursuant to Clause 166, wherein the parameters of the pupil plane distribution of the charged particle beam include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 186. A non-transitory computer-readable medium pursuant to Clause 166, wherein the surface includes the surface of the sample to be inspected. 187. A non-transitory computer-readable medium pursuant to Clause 186, wherein the surface of the sample to be inspected includes one of a peripheral unpatterned area, scribing, measurement markings, or a featureless area within the die. 188. A non-transitory computer-readable medium pursuant to Clause 166, wherein the surface includes a surface configured to support a sample platform for examination. 189. A non-transitory computer-readable medium pursuant to Clause 166, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 190. A non-transitory computer-readable medium pursuant to Clause 166, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 191. A non-transitory computer-readable medium pursuant to Clause 166, wherein the arrival of detected charged particles includes at least 70% backscattered electrons. 192. A non-transitory computer-readable medium pursuant to Clause 166, wherein the operation further includes: After the adjustment is performed, the parameters of the pupil plane distribution are determined to be no lower than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another parameter value for the pupil plane distribution based on another spatial distribution information; and Another adjustment is made to the charged particle beam system based on another value. 193. A charged particle beam device, comprising: The charged particle beam source is configured to generate a primary charged particle beam; A charged particle optical system is configured to guide a primary charged particle beam to a surface. The controller, including one or more processors and configured to cause the charged particle beam device to perform operations, includes: A charged particle beam system is used to irradiate a surface with a charged particle beam, causing charged particles to be emitted from the surface. To obtain spatial distribution information of charged particles arriving at the charged particle detector of the charged particle beam system; The parameters of the pupil plane distribution of the charged particle beam are determined based on spatial distribution information; Adjustments are performed on the charged particle beam system based on determined parameters; and Use a detector to examine the sample. 194. A charged particle beam device according to Clause 193, wherein spatial distribution information includes an intensity map of charged particle arrivals on a detector. 195. A charged particle beam device according to Clause 194, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 196. Charged particle beam device according to Clause 195, wherein the boundary is defined based on an intensity threshold. 197. Charged particle beam apparatus according to Clause 195, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 198. A charged particle beam device according to Clause 197, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 199. A charged particle beam device pursuant to Clause 195, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 200. A charged particle beam apparatus pursuant to Clause 193, wherein spatial distribution information includes one of the shape, size, or centroid location of the distribution to which charged particles arrive at the detector. 201. A charged particle beam apparatus according to Clause 193, wherein determining parameter values ​​for the pupil plane distribution based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 202. A charged particle beam device pursuant to Clause 201, wherein a plurality of reference distributions comprise a set of model aberrations. 203. A charged particle beam apparatus according to Clause 202, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 204. A charged particle beam apparatus pursuant to Clause 202, wherein the charged particle detector is a reference charged particle detector. 205. A charged particle beam apparatus according to Clause 202, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 206. A charged particle beam apparatus according to Clause 202, wherein model aberrations are based on a set of orthogonal functions on a disk. 207. A charged particle beam apparatus according to Clause 193, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements. 208. A charged particle beam apparatus according to Clause 207, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 209. A charged particle beam device according to Clause 193, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the asymmetry parameters in at least four segments. 210. A charged particle beam device according to Clause 193, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the focusing parameters. 211. A charged particle beam apparatus according to Clause 193, wherein the parameters of the pupil plane distribution of the charged particle beam include one of first-order aberrations, second-order aberrations, or third-order aberrations. 212. A charged particle beam apparatus according to Clause 193, wherein the parameters of the pupil plane distribution of the charged particle beam include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 213. A charged particle beam apparatus according to Clause 193, wherein the surface includes the surface of the sample to be inspected. 214. A charged particle beam apparatus pursuant to Clause 213, wherein the surface of the sample to be inspected includes one of an unpatterned peripheral region, scribing, measurement markings, or a featureless inner region of the die. 215. A charged particle beam apparatus according to Clause 193, wherein the surface includes a sample platform configured to support a sample to be examined. 216. A charged particle beam device according to Clause 193, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 217. A charged particle beam device pursuant to Clause 193, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 218. A charged particle beam device according to Clause 193, wherein the detected charged particle arrival includes at least 70% backscattered electron arrival. 219. The charged particle beam device pursuant to Clause 193, wherein operation further includes: After the adjustment is performed, the parameters of the pupil plane distribution are determined to be no lower than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another parameter value for the pupil plane distribution based on another spatial distribution information; and Another adjustment is made to the charged particle beam system based on another value. 220. A charged particle beam method, comprising: A charged particle beam system is used to irradiate a surface with a charged particle beam, causing charged particles to be emitted from the surface. To obtain spatial distribution information of charged particles arriving at the charged particle detector of the charged particle beam system; The parameters of the pupil plane distribution of the charged particle beam are determined based on spatial distribution information; Adjustments are performed on the charged particle beam system based on determined parameters; and Use a detector to examine the sample. 221. The charged particle beam method according to Clause 220, wherein the spatial distribution information includes an intensity map of charged particle arrivals on the detector. 222. The charged particle beam method according to Clause 221, wherein: Spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map. 223. The charged particle beam method according to Clause 222, wherein the boundary is defined based on an intensity threshold. 224. The charged particle beam method according to Clause 222, wherein the boundary is defined as a threshold percentage including the energy detected on the detector. 225. The charged particle beam method according to Clause 224, wherein the threshold percentage is greater than 90% and less than 100% of the energy detected on the detector. 226. The charged particle beam method according to Clause 222, wherein the boundary is determined based on either a clustering algorithm or a contour fitting algorithm. 227. The charged particle beam method according to Clause 220, wherein the spatial distribution information includes one of the shape, size or centroid location of the distribution of charged particles arriving at the detector. 228. The charged particle beam method according to Clause 220, wherein determining the parameter values ​​of the pupil plane distribution based on spatial distribution information includes comparing the spatial distribution information with multiple reference distributions. 229. The charged particle beam method according to Clause 228, wherein multiple reference distributions comprise a set of model aberrations. 230. The charged particle beam method according to Clause 229, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings. 231. The charged particle beam method according to Clause 229, wherein the charged particle detector is a reference charged particle detector. 232. The charged particle beam method according to Clause 229, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings. 233. The charged particle beam method according to Clause 229, wherein the model aberrations are based on a set of orthogonal functions on a disk. 234. The charged particle beam method according to Clause 220, wherein the charged particle detector includes a pixelated charged particle detector having an array of sensing elements. 235. The charged particle beam method according to Clause 234, wherein the pixelated charged particle detector includes at least 100 sensing elements configured to detect independent signal strength values. 236. The charged particle beam method according to Clause 220, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least four segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the asymmetry parameters in at least four segments. 237. The charged particle beam method according to Clause 220, wherein: The charged particle detector includes a segmented charged particle detector, which comprises at least two annular segments; and Determining the parameter values ​​for the pupil plane distribution includes determining the focusing parameters. 238. The charged particle beam method according to Clause 220, wherein the parameters of the pupil plane distribution of the charged particle beam include one of first-order aberrations, second-order aberrations, or third-order aberrations. 239. The charged particle beam method according to Clause 220, wherein the parameters of the pupil plane distribution of the charged particle beam include one of defocus, astigmatism, beam tilt, beam shift, coma, pincushion distortion, barrel distortion, spherical aberration, chromatic aberration, or field curvature. 240. The charged particle beam method according to Clause 220, wherein the surface includes the surface of the sample to be inspected. 241. The charged particle beam method according to Clause 240, wherein the surface of the sample to be inspected includes one of the peripheral unpatterned area, scribing, measurement markings, or a featureless inner region of the die. 242. The charged particle beam method according to Clause 220, wherein the surface includes a sample platform configured to support the sample to be examined. 243. The charged particle beam method according to Clause 220, wherein the surface comprises a heavy metal layer having an atomic number of at least 47. 244. The charged particle beam method according to Clause 220, wherein the surface comprises one of silver, gold, titanium, cobalt, copper or ruthenium. 245. The charged particle beam method according to Clause 220, wherein the detected charged particle arrivals include at least 70% backscattered electron arrivals. 246. The charged particle beam method pursuant to Clause 220 further includes: After the adjustment is performed, the parameters of the pupil plane distribution are determined to be no lower than the predetermined threshold. The surface was further irradiated with charged particle beams using a charged particle beam system; To obtain another spatial distribution information of charged particles detected by the charged particle detector; Determine another parameter value for the pupil plane distribution based on another spatial distribution information; and Another adjustment is made to the charged particle beam system based on another value.

[0114] Some embodiments of this disclosure have been described with respect to electron beam systems (such as SEM) having electron detectors for detecting the arrival of electrons. However, this disclosure is not limited thereto. It should be understood that the embodiments disclosed above can be applied to other systems, such as other non-SEM electron beam systems or non-electron-based charged particle beam systems. Furthermore, it should be understood that other charged particles or other classes of electrons are contemplated within the scope of this disclosure.

[0115] The block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer hardware or software products according to various exemplary embodiments of the present disclosure. In this regard, each block in the diagrams may represent certain arithmetic or logical operations that can be implemented using hardware such as electronic circuits. A block may also represent a module, segment, or code portion, including one or more executable instructions for implementing a specified logical function. It should be understood that in some alternative implementations, the functions indicated in the blocks may not occur in the order mentioned in the drawings. For example, two blocks shown consecutively may be executed or implemented substantially concurrently, or the two blocks may sometimes be executed in reverse order, depending on the functionality involved. Some blocks may also be omitted. It should also be understood that each block of the block diagram, and combinations of blocks, may be implemented by a dedicated hardware-based system (performing the specified function or action) or a combination of dedicated hardware and computer instructions.

[0116] It should be understood that the embodiments of this disclosure are not limited to the precise constructions described above and illustrated in the accompanying drawings, and various modifications and changes can be made without departing from its scope. For example, a charged particle inspection system may be merely one example of a charged particle beam system consistent with embodiments of this disclosure.

Claims

1. A non-transitory computer-readable medium storing an instruction set executable by at least one processor of a device to cause the device to perform operations, the operations including: The surface is irradiated with charged particle beams using a charged particle beam system; Obtain spatial distribution information of charged particles detected by the charged particle detector; The aberration values ​​of the charged particle beam are determined based on the spatial distribution information; and Adjustments are performed on the charged particle beam system based on the determined aberration values.

2. The non-transitory computer-readable medium of claim 1, wherein the spatial distribution information includes an intensity map of charged particle arrivals on the detector.

3. The non-transitory computer-readable medium according to claim 2, wherein: The spatial distribution information includes the distribution boundary reached by charged particles on the detector; and The boundary is defined based on the intensity map.

4. The non-transitory computer-readable medium of claim 3, wherein the boundary is defined based on an intensity threshold.

5. The non-transitory computer-readable medium of claim 3, wherein the boundary is defined as a threshold percentage of the energy detected on the detector.

6. The non-transitory computer-readable medium of claim 5, wherein the threshold percentage is greater than 90% of the energy detected on the detector and less than 100% of the energy detected on the detector.

7. The non-transitory computer-readable medium of claim 3, wherein the boundary is determined based on one of a clustering algorithm or a contour fitting algorithm.

8. The non-transitory computer-readable medium of claim 1, wherein the spatial distribution information includes one of the following: the shape, size, or centroid location of the distribution reached by charged particles on the detector.

9. The non-transitory computer-readable medium according to claim 1, wherein determining the aberration value of the charged particle beam based on the spatial distribution information comprises: The spatial distribution information is compared with multiple reference distributions.

10. The non-transitory computer-readable medium of claim 9, wherein the plurality of reference distributions comprises a set of model aberrations.

11. The non-transitory computer-readable medium of claim 10, wherein the model aberration is based on multiple measurements on a reference charged particle detector under multiple different exposure settings.

12. The non-transitory computer-readable medium of claim 10, wherein the charged particle detector is the reference charged particle detector.

13. The non-transitory computer-readable medium of claim 10, wherein the model aberration is based on multiple measurements on the pupil charged particle detector under multiple different exposure settings.

14. The non-transitory computer-readable medium of claim 10, wherein the model aberration is based on a set of orthogonal functions on a disk.

15. The non-transitory computer-readable medium of claim 1, wherein the charged particle detector comprises a pixelated charged particle detector having an array of sensing elements.

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