Method and apparatus for charged particle detection

Abstract

A method and apparatus for detecting charged particles are provided. The detection system includes a signal processing circuit (502) configured to generate a set of intensity gradients based on electron intensity data received from a plurality of electron sensing elements (244). The detection system further includes a beam spot processing module (506) configured to: determine at least one boundary of a beam spot based on the set of intensity gradients; and determine, based on said at least one boundary, that a first group of electron sensing elements is located within the beam spot. The beam spot processing module may be further configured to: determine an intensity value of the beam spot based on electron intensity data received from the first group of electron sensing elements, and also generate an image of a wafer based on the intensity value.

Description

[0001] This application is a divisional application of the invention patent application with an international filing date of February 1, 2018, which entered the Chinese national phase on August 6, 2019, with Chinese national application number 201880010544.2 and an invention title of "Method and Apparatus for Detecting Charged Particles". Technical Field

[0002] This disclosure generally relates to the field of charged particle beams, and more specifically, to a method and apparatus for the detection of charged particles. Background Technology

[0003] In the manufacturing process of integrated circuits (ICs), unfinished or completed circuit components are inspected to ensure they are manufactured according to the design and free of defects. Inspection systems using optical microscopes typically have a resolution as low as a few hundred nanometers; and this resolution is limited by the wavelength of light. As the physical dimensions of IC components continue to shrink to below 100 nanometers or even below 10 nanometers, inspection systems capable of providing higher resolution than those using optical microscopes are needed.

[0004] Charged particle (e.g., electron) beam microscopy (such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM)) capable of resolutions as low as less than 1 nanometer serves as a practical tool for inspecting IC components with feature sizes less than 100 nanometers. Using SEM, electrons from a single primary electron beam or multiple primary electron beams can be focused at a predetermined scan location on the wafer being inspected. The primary electrons interact with the wafer and can be backscattered or cause the wafer to emit secondary electrons. The intensity of the electron beam, including both backscattered and secondary electrons, can vary based on the properties of the wafer's internal and / or external structure.

[0005] An electron beam, comprising backscattered electrons and secondary electrons, can form one or more beam spots at predetermined locations on the surface of an electron detector. The electron detector can generate an electrical signal (e.g., current, voltage, etc.) representing the intensity of the detected electron beam. A measurement circuit system (e.g., an analog-to-digital converter) can be used to measure the electrical signal to obtain the distribution of the detected electrons. The electron distribution data collected during the detection time window, combined with corresponding scan path data of one or more primary electron beams incident on the wafer surface, can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the wafer's internal and / or external structure and can be used to reveal any defects that may exist in the wafer.

[0006] The fidelity of image reconstruction determines how closely the image represents the wafer structure. Fidelity can be reduced by noise signals that are not associated with the primary or secondary electrons emitted by the wafer. Various potential sources of noise exist. For example, an electron detector may generate dark currents with or without receiving any electrons. Dark currents can be added to a current actually proportional to the detected electrons, thus introducing error data into the image reconstruction. Furthermore, the electron detector may fail to generate current due to a malfunction or generate a current amount that does not reflect the number of electrons received. Further, in cases where multiple primary electron beams scan the wafer and multiple electron beams are emitted by the wafer under inspection, electrons from adjacent beams emitted from the wafer may reach the same location on the electron detector surface due to aberrations and dispersion in the electron optics subsystem. Therefore, beam spots formed by adjacent electron beams may partially overlap, leading to crosstalk. All of these can be added as noise components to the output signal of the electron detector. Therefore, the output signal of the electron detector may include noise components independent of the specific wafer structure being inspected, and thus the fidelity of image reconstruction based on these output signals can be reduced. Summary of the Invention

[0007] Embodiments of this disclosure provide systems and methods for detecting charged particles. In one embodiment, a detection system is provided. The detection system includes signal processing circuitry configured to generate a set of intensity gradients based on electron intensity data received from a plurality of electron sensing elements. The detection system further includes a beam spot processing module configured to determine at least one boundary of a beam spot based on the set of intensity gradients; and to determine, based on the at least one boundary, that a first set of electron sensing elements of the plurality of electron sensing elements is within the beam spot.

[0008] In another embodiment, a detection system is provided. The detection system includes a beamspot processing module. The beamspot processing module is configured to: acquire a set of intensity gradients generated based on gradients in intensity signals between adjacent electronic sensing elements among a plurality of electronic sensing elements. The beamspot processing module is further configured to: determine at least one boundary of the beamspot based on the set of intensity gradients. The beamspot processing module is further configured to: determine that a first group of electronic sensing elements among the plurality of electronic sensing elements is within the beamspot based on the at least one boundary.

[0009] In another embodiment, a detection system is provided. The detection system includes a signal processing circuit configured to generate a set of intensity gradients based on electron intensity data received from a plurality of electron sensing elements. The detection system further includes a beamspot processing module configured to determine a first boundary of a first beamspot and a second boundary of a second beamspot based on the set of intensity gradients. The beamspot processing module is also configured to determine a first group of electron sensing elements within the first beamspot based on the first boundary, and a second group of electron sensing elements within the second beamspot based on the second boundary. The beamspot processing module is further configured to determine an overlap region between the first and second beamspots based on the first and second boundaries.

[0010] In another embodiment, a detection system is provided. The detection system includes a beamspot processing module configured to: acquire a set of intensity gradients generated based on gradients in intensity signals between adjacent electronic sensing elements among a plurality of electronic sensing elements. The beamspot processing module is further configured to: determine a first boundary of a first beamspot and a second boundary of a second beamspot based on the set of intensity gradients. The beamspot processing module is further configured to: determine a first group of electronic sensing elements among the plurality of electronic sensing elements within the first beamspot based on the first boundary, and determine a second group of electronic sensing elements among the plurality of electronic sensing elements within the second beamspot based on the second boundary. The beamspot processing module is also configured to: determine an overlap region between the first and second beamspots based on the first and second boundaries.

[0011] In another embodiment, an electron detection system is provided. The electron detection system includes a plurality of electron sensing elements configured to receive at least one electron beam comprising secondary or backscattered electrons from a wafer. The electron detection system also includes a processing system. The processing system includes an intensity gradient determination circuit configured to determine a set of intensity gradients based on electron intensity data received from each of the plurality of electron sensing elements. The processing system also includes a beam spot boundary determination module configured to determine at least one boundary of the beam spot of one of the at least received electron beams based on the set of intensity gradients, and to determine that a first group of electron sensing elements is within the beam spot based on the at least one boundary. The processing system also includes a beam spot intensity determination module configured to determine an intensity value of the beam spot based on electron intensity data received from the first group of electron sensing elements. The processing system also includes an image reconstruction module configured to generate an image of the wafer based on the intensity values.

[0012] In another embodiment, a method is provided. The method includes determining a set of intensity gradients based on electron intensity data received from each of a plurality of electron sensing elements. The method further includes determining at least one boundary of a beam spot based on the set of intensity gradients.

[0013] In another embodiment, a method is provided. The method includes determining a set of intensity gradients based on electron intensity data received from each of a plurality of electron sensing elements. The method further includes determining a first boundary of a first beam spot and a second boundary of a second beam spot based on the set of intensity gradients. The method further includes determining a first group of electron sensing elements within the first beam spot based on the first boundary, and determining a second group of electron sensing elements within the second beam spot based on the second boundary. The method further includes determining an overlap region between the first and second beam spots based on the first and second boundaries.

[0014] In another embodiment, a non-transitory computer-readable storage medium is provided. The storage medium stores instructions executable by a computing device including one or more processors to cause the computing device to perform a method. The method includes: determining a set of intensity gradients based on electron intensity data received from each of a plurality of electron sensing elements, and determining at least one boundary of a beam spot based on the set of intensity gradients.

[0015] In another embodiment, a non-transitory computer-readable storage medium is provided. The storage medium stores instructions executable by a computing device including one or more processors to cause the computing device to perform a method. The method includes: determining a set of intensity gradients based on electron intensity data received from each of a plurality of electron sensing elements. The method further includes: determining a first boundary of a first beam spot and a second boundary of a second beam spot based on the set of intensity gradients. The method further includes: determining a first group of electron sensing elements within the first beam spot based on the first boundary, and determining a second group of electron sensing elements within the second beam spot based on the second boundary. The method further includes: determining an overlap region between the first and second beam spots based on the first and second boundaries.

[0016] Additional objects and advantages of the disclosed embodiments will be set forth in part in the description which follows, and will be apparent in part from this specification, or may be learned by practice of the embodiments. The objects and advantages of the disclosed embodiments may be realized and obtained by means of the elements and combinations set forth in the claims.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit the claimed disclosed embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0019] Figure 2 The illustration shows an embodiment consistent with this disclosure, which may be... Figure 1 A schematic diagram of an exemplary electron beam tool, which is part of an exemplary electron beam inspection system.

[0020] Figures 3A to 3D This is a diagram illustrating an exemplary method for determining the intensity of an electron beam spot, consistent with embodiments of the present disclosure.

[0021] Figures 4A to 4C This is a diagram illustrating an exemplary method for reducing noise components from a determined intensity of an electron beam spot, consistent with embodiments of the present disclosure.

[0022] Figures 5A to 5C This is a schematic diagram illustrating an exemplary system for processing the output of an electronic detector, consistent with embodiments of the present disclosure.

[0023] Figure 6 This is a flowchart illustrating an exemplary method for inspecting a wafer, consistent with embodiments of this disclosure.

[0024] Figure 7 This is a flowchart illustrating an exemplary method for inspecting a wafer, consistent with embodiments of this disclosure. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same reference numerals in different drawings denote the same or similar elements. The embodiments set forth in the following description of the exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with aspects of the invention as recited in the appended claims.

[0026] Embodiments of this disclosure provide an electron beam tool with an electron detector and a preprocessing circuit system, a signal processing circuit system, and a post-processing circuit system coupled to the electron detector. The electron detector can be configured to receive backscattered primary and secondary electrons emitted from a wafer. The received electrons form one or more beam spots on the surface of the detector. The surface can include a plurality of electron sensing elements configured to generate electrical signals in response to the received electrons. The preprocessing and signal processing circuit systems can be configured to generate an indication related to the amplitude of the generated electrical signals. The post-processing circuit system can be configured to determine, based on the generated indication, which electron sensing element is located within the primary boundary of the beam spot, and to generate a value representing the intensity of the beam spot based on the determined primary boundary. Using this arrangement, the disclosed embodiments can determine which electron sensing elements are located outside the primary boundary of the beam spot and estimate noise signals based on the outputs of these sensing elements. The post-processing circuit system can also compensate for the estimated noise signals when generating beam spot intensity data. Therefore, both the fidelity and speed of wafer image reconstruction can be improved.

[0027] The post-processing circuitry can also be configured to determine the secondary boundaries of the beam spot. Electrons in the incident electron beam can have different properties, for example, different energies due to different generation processes. The distribution or concentration of electrons with different properties can vary at different locations within the electron beam, forming a corresponding intensity pattern in the detected electron beam spot. The determined primary and secondary boundaries can be used to group the output signals of the corresponding electron sensing elements. Groups can be formed such that their geometric arrangement matches the pattern of the corresponding electron beam spot. As an example, a portion of the electron beam spot detected by the electron sensing element within the secondary beam boundary may include almost all backscattered electrons, and a portion of the electron beam spot detected by the electron sensing element between the primary and secondary beam boundaries may include almost all secondary electrons. Thus, the formed groups can generate intensity information for the entire detected beam, as well as intensity information corresponding to the backscattered electron portion and the secondary electron portion of the electron beam. Therefore, the disclosed embodiments can provide additional information about the detected electron beam spot, and thus provide additional properties of the sample under study.

[0028] In systems comprising multiple detection electron beams, crosstalk in signals from adjacent beams is caused by aberrations and dispersion within the electron optics subsystem. Electrons in each beam can be scattered along their path to the sensing surface of the electron detector, causing overlap between adjacent electron beam spots. Grouping the output signals from the electron sensing element based on the determined beam boundaries can be used to detect crosstalk between adjacent detection beams. The post-processing circuitry can also compensate for the determined crosstalk signal when generating intensity data for multiple beam spots. Therefore, both the fidelity and speed of wafer image reconstruction can be improved. In some embodiments, the aperture within the electron optics subsystem used to reduce crosstalk can be removed. This simplifies the design, manufacture, and maintenance of electron beam tools. Furthermore, the aperture within the electron optics subsystem can cause a significant reduction in the intensity of the detected electron beam and a decrease in the signal-to-noise ratio (SNR). The crosstalk determination and compensation provided by the disclosed embodiments can be used to adjust the balance between SNR and crosstalk in real time. The ability to adjust the balance between SNR and crosstalk in real time can greatly improve the flexibility and performance of electron beam tools.

[0029] Furthermore, the disclosed embodiments may include a signal processing circuitry system to perform beam boundary determination and beam intensity determination in real time. This enables high-speed performance compared to systems that use post-processing algorithms to perform beam boundary determination and beam intensity determination functions. High-speed real-time performance provides information about how the electron optics subsystem is performing in real time and allows for the detection and resolution of any performance deviations (e.g., the shape and trajectory of each beam, the geometry of the electron beam grid, unintended movement of some or all beams due to imperfections in component manufacturing and assembly, drift during long-term operation). Furthermore, anti-deflection systems are used in conventional systems to eliminate movement of the secondary electron beam. Synchronizing the anti-deflection system with the primary electron beam deflector is technically challenging. The disclosed embodiments can track beam spot movement in real time, therefore, in some embodiments, the anti-deflection system can be removed.

[0030] Furthermore, the beam intensity determination in the disclosed embodiments can be performed by grouping the signals corresponding to a large number of electronic sensing elements. If one or more electronic sensing elements in a group are unable to operate properly due to contamination of the electronic sensing element surface, damage caused by an accident (e.g., severe arcing in the vacuum cavity housing the electro-optics subsystem), or failure of the electronic sensing element due to defects introduced during the manufacturing process, the grouping can still achieve the beam intensity determination function by excluding the inoperable electronic sensing elements from the group. This can improve the reliability and fault tolerance of the detection system.

[0031] In some embodiments, the signal processing circuitry and post-processing circuitry can also be configured to scan the electronic signal corresponding to the electronic sensing element and generate an image of one or more electron beam spots applied to the detector surface. The scan rate can be configured to generate the image at a frame rate lower than the update rate of the groups used to determine beam intensity. However, the image can provide detailed information about the intensity distribution of the electron beam spots on the detector surface and can be used to design, optimize, and evaluate the performance of the electro-optical system. Furthermore, the generated image and the determined beam boundary can be used to detect any deviations in the shape or trajectory of one or more detected electron beams due to drift during long-term operation of the system, and can be used to compensate for these effects.

[0032] Referring now to the exemplary embodiments illustrated in the accompanying drawings. Although the following embodiments are described in the context of using an electron beam, this disclosure is not limited thereto. Similarly, other types of charged particle beams can be applied.

[0033] Now refer to Figure 1 , Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of this disclosure is illustrated. Figure 1 As shown, the EBI system 100 includes a main chamber 101, a loading / locking chamber 102, an electron beam tool 104, and an equipment front-end module (EFEM) 106. The electron beam tool 104 is located within the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include multiple additional loading ports. The first loading port 106a and the second loading port 106b receive a front-opening wafer transfer cassette (FOUP) containing a wafer to be inspected (e.g., one or more semiconductor wafers made of (multiple) other materials) or a sample (wafers and samples are collectively referred to as “wafers” hereinafter).

[0034] One or more robotic arms (not shown) in EFEM 106 transport the wafer to loading / locking chamber 102. Loading / locking chamber 102 is connected to a loading / locking vacuum pump system (not shown), which removes gas molecules from loading / locking chamber 102 to achieve a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) transport the wafer from loading / locking chamber 102 to main chamber 101. Main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from main chamber 101 to achieve a second pressure below the first pressure. After reaching the second pressure, the wafer is inspected by electron beam tool 104.

[0035] Now refer to Figure 2 , Figure 2The diagram illustrates an electron beam tool 104 (also referred to herein as apparatus 104), which includes an electron source 202, a bore 204, a condenser lens 206, a primary electron beam 210 emanating from the electron source 202, a source conversion unit 212, multiple sub-beams 214, 216, and 218 of the primary electron beam 210, a primary projection optics system 220, and a wafer stage (not shown). Figure 2 (As shown in the diagram), multiple secondary electron beams 236, 238, and 240, a secondary optical system 242, and an electronic 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 electronic detection device 244 may include detection elements 246, 248, and 250.

[0036] The electronic source 202, the gun hole 204, the condenser 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 device 104. The secondary optical system 242 and the electronic detection device 244 can be aligned with the secondary optical axis 252 of the device 104.

[0037] Electron source 202 may include a cathode, an extractor, or an anode, wherein primary electrons may be emitted from the cathode and extracted or accelerated to form a primary electron beam 210 with a cross (virtual or real) 208. The primary electron beam 210 can be considered to be emitted from the cross 208. A bore 204 may block peripheral electrons of the primary electron beam 210 to reduce the Coulomb effect. The Coulomb effect can cause an increase in the size of probe spots 270, 272, and 274.

[0038] Source conversion unit 212 may include an array of image forming elements (not in...) Figure 2 (shown in) and beam-limited aperture array (not shown in) Figure 2 (As shown in the figure). The image forming element array may include an array of micro-deflectors or microlenses. The image forming element array can form multiple parallel images (virtual or real) at intersection 208 with multiple sub-beams 214, 216, and 218 of the primary electron beam 210. The beam confinement aperture array can confine multiple sub-beams 214, 216, and 218.

[0039] The condenser lens 206 can focus the primary electron beam 210. The current of the sub-beams 214, 216, and 218 downstream of the source conversion unit 212 can be changed by adjusting the focusing capability of the condenser lens 206 or by changing the radial size of the corresponding beam-limiting aperture within the beam-limiting aperture array. The objective lens 228 can focus the sub-beams 214, 216, and 218 onto the wafer 230 for inspection and can form multiple probe spots 270, 272, and 274 on the surface of the wafer 230.

[0040] Beam splitter 222 can be a Wien filter type beam splitter, which includes electrostatic deflectors that generate electrostatic dipole fields and magnetic dipole fields. In some embodiments, if they are applied, the force exerted on the electrons of sub-bundles 214, 216, and 218 by the electrostatic dipole field and the force exerted on the electrons by the magnetic dipole field can be equal in magnitude and opposite in direction. Therefore, sub-bundles 214, 216, and 218 can pass directly through beam splitter 222 with zero deflection angle. However, the total dispersion of sub-bundles 214, 216, and 218 generated by beam splitter 222 can be non-zero. Regarding the dispersion plane 224 of beam splitter 222, Figure 2 A sub-beam 214 with a nominal energy V0 and an energy spread ΔV is shown, distributed into a sub-beam portion 262 corresponding to energy V0, a ​​sub-beam portion 264 corresponding to energy V0 + ΔV / 2, and a sub-beam portion 266 corresponding to energy V0 - ΔV / 2. The total force exerted by the beam splitter 222 on the electrons of the secondary electron beams 236, 238, and 240 can be non-zero. Therefore, the beam splitter 222 can separate the secondary electron beams 236, 238, and 240 from the sub-beams 214, 216, and 218, and guide the secondary electron beams 236, 238, and 240 toward the secondary optical system 242.

[0041] The deflection scanning unit 226 can deflect sub-beams 214, 216, and 218 to scan probe spots 270, 272, and 274 on the surface region of wafer 230. In response to the incident sub-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 an energy distribution, including secondary electrons (energy ≤ 50 eV) and backscattered electrons (energy between 50 eV and the landing energy of sub-beams 214, 216, and 218). The secondary optical system 242 can focus the secondary electron beams 236, 238, and 240 onto the detection elements 246, 248, and 250 of the electron detection device 244. Detection elements 246, 248 and 250 can detect the corresponding secondary electron beams 236, 238 and 240 and generate corresponding signals for reconstructing images of the surface regions of the wafer 230.

[0042] Now refer to Figure 3A , Figure 3AAn exemplary structure of the sensor surface 300 of the electronic inspection device 244 is illustrated. The sensor surface 300 can be divided into four regions 302A to 302D (2×2 rectangular grids), each region 302 capable of receiving a corresponding beam spot 304 emitted from a specific location on the wafer. All beam spots 304A to 304D have an ideal circular shape and no trajectory offset. Moreover, although four regions are shown, it should be understood that any number of regions can be used.

[0043] Each sensor region may include an array of electronic sensing elements 306. For example, the electronic sensing elements may include PIN diodes, electron multiplier tubes (EMTs), etc. Furthermore, it should be understood that although... Figure 3A Each region 302 is shown as a predefined region separated from each other, each having its own sensing element 306; however, it should be understood that these predefined regions may not exist, for example, such as... Figure 4A The surface sensor 400. For example, instead of having 4 predefined regions, each with 81 sensing elements (a 9x9 grid of sensing elements), the sensor surface can have an 18x18 grid of sensing elements and still be able to sense four beams.

[0044] The electron sensing element 306 can generate a current signal corresponding to the electrons received in the sensor region. A preprocessing circuit can convert the generated current signal into a voltage signal (representing the intensity of the received electron beam spot). For example, the preprocessing circuit may include a high-speed transimpedance amplifier. For instance, the processing system can generate the intensity signal of the electron beam spot by summing the voltages generated by the electron sensing element located in the sensor region, correlate the intensity signal with scan path data of the primary electron beam incident on the wafer, and construct an image of the wafer based on the correlation.

[0045] In some embodiments, the processing system may selectively sum the voltages generated by some electronic sensing elements 306 to generate a beam spot intensity value. This selection may be based on determining which electronic sensing element is located within the beam spot.

[0046] In some embodiments, the processing system can identify which electronic sensing element is located outside the beam spot and which is located inside the beam spot by identifying the boundaries of the beam spot. For example, refer to Figure 3B The processing system can identify the primary boundaries 312A to 312B and secondary boundaries 314A to 314B of beam spots 304A to 304B. The primary boundary 312 can be configured to surround a set of electronic sensing elements 306, wherein their voltage output is included to determine the intensity of the beam spot. Therefore, the determination of a set of electronic sensing elements within the beam spot is possible.

[0047] The secondary boundary 314 can be configured to surround the central portion of the beam spot and can be used to provide some geometric information about the beam spot. For example, the geometric information may include the shape of the beam spot, one or more trajectories of the beam spot, etc. Here, the trajectory may refer to a predetermined location within the beam spot, such as the center. As discussed in more detail below, the processing system can also determine the primary boundary 312 based on the secondary boundary 314.

[0048] Furthermore, based on trajectory information, the processing system can also track drift in the position of the beam spot 304, for example, due to defects in the electro-optical components or system introduced during manufacturing or assembly and / or drift during long-term operation of the system. The processing system can update the boundary determination and a set of electronic sensing elements to be included in the intensity determination to mitigate the impact of drift on the accuracy of the intensity determination. Further, the processing system can track any displacement in the electron beam spot, so anti-deflection components used for tracking and compensating for electron beam deflection can be removed from the secondary optics system. This simplifies the design, manufacture, and maintenance of the electron beam tool 104.

[0049] The selection of the electronic sensing elements 306 used to form each group of electronic sensing elements surrounded by primary or secondary boundaries 312 and 314 can be determined by a specified electron collection rate for each beam spot, which is related to the overall image signal strength and signal-to-noise ratio, signal crosstalk between adjacent electron beams, and the corresponding shape and trajectory of each electron beam spot. The formation of each group can be static or dynamically varied depending on whether real-time tracking and compensation for changes in the shape and trajectory of each corresponding beam spot is required. By providing the ability to acquire beam position and shape in real time, the performance of the electro-optical system (e.g., primary projection optics system 220) can be continuously monitored. Furthermore, the collected information on beam positioning and shape can facilitate electro-optical system adjustments during system assembly and maintenance processes, thereby enabling real-time automatic alignment between the electro-optical system and the electronic detection equipment. Therefore, although... Figure 3B A beam spot 304B with a shape deviating from the preferred circular shape is shown, but deviations such as position, shape, and grid information caused by drift in the electro-optical system or defects in components of the electro-optical system can be compensated in real time.

[0050] In some embodiments, determining the primary and secondary boundaries can be based on a predetermined pattern of detecting intensity gradients across adjacent electronic sensing elements. Referring now... Figure 3C , Figure 3C An example of a predetermined pattern used to determine the primary boundary 312 is illustrated. Figure 3C The intensity map 330 and intensity curve 340 are illustrated. Intensity map 330 illustrates the beam spot (e.g., Figure 3AThe intensity distribution of the beam spot (304) is such that each square represents the intensity of an electron received by an electron sensing element, with darker colors indicating relatively higher intensities. The processing system can determine that electron sensing elements represented by colors lighter than a predetermined threshold (e.g., white) are outside the beam spot, and electron sensing elements represented by colors darker than the determined threshold (e.g., gray) are inside the beam spot. Based on these determinations, the processing system can exclude the output of electron sensing elements represented by white.

[0051] Furthermore, intensity curve 340 illustrates the variation of electron intensity along axis 345 on intensity map 330. For example... Figure 3C As shown, intensity curve 340 illustrates the different intensities at different locations. For example, near the center of the beam spot (labeled 350), the intensity is higher than near the boundary of the beam spot (labeled 355). The difference in intensity can be attributed to various factors, including the tip size of the electron source 202, aberrations of the electron optics system, and electron dispersion. Moreover, in some embodiments, the intensity can be determined by the sample morphology of the scattered electrons, the material of the backscattered electrons, the charging conditions on the sample surface, landing energy, etc.

[0052] An intensity gradient can be generated based on a comparison of the electron intensity outputs between neighboring electron sensing elements. For example, the output of a signal conditioning circuit coupled to a corresponding electron sensing element on the sensor surface of the electron detection device 244 can be connected to a set of voltage comparators configured to compare the output voltages (representing the received electron intensity) between neighboring electron sensing elements. The set of voltage comparators can generate a set of decisions. The processing system can then track the intensity gradient based on these decisions and determine the location of the intensity gradient change on the sensor surface as part of the primary boundary 312. For example, referring back... Figure 3C The voltage decision curve 360 ​​illustrates the distribution of voltage comparator decisions corresponding to the intensity changes illustrated in the intensity curve 340. This decision can represent the comparison result of the output voltages between adjacent electronic sensing elements, where -1 indicates that the output voltage of the electronic sensing element on the left is higher than that of the electronic sensing element on the right, and +1 indicates the opposite result.

[0053] The comparison results can reflect the characteristic patterns of the intensity gradient at the beam spot boundary and within the beam spot. For example, as... Figure 3CAs shown, the voltage comparator decision 364 corresponding to intensity 355 can exhibit more switching between +1 and -1, possibly due to the difference in signal level of the electron intensity output from the processing system, which corresponds to the electron current intensity received by adjacent electron sensing elements and is below the noise level. Therefore, comparator decision 364 (corresponding to the boundary of the beam spot) may be susceptible to random noise and can switch in either direction. On the other hand, since the difference in signal level of the electron intensity output is higher than the noise level, the comparator decision 362 corresponding to intensity 350 can be more stable on a set of adjacent electron sensing elements. Based on the switching pattern of the comparator output, the processing system can group the comparator decisions in the voltage decision curve 360 ​​into two groups corresponding to intensity gradients 362 and 364. Based on the location of the electron sensing elements that generate the two sets of comparator decisions, the processing system can identify the location on the sensor surface where the transition between intensity gradients 362 and 364 occurs, which can be a location marked as location "A". The processing system can then determine the identified location as part of the primary boundary 312. The processing system can perform similar processing on the voltage comparator decisions of each row and column of electronic components to determine a set of locations on the primary boundary 312 that constitute the sensor surface.

[0054] The processing system can also determine the secondary boundary 314 by detecting other predetermined patterns in the voltage comparator decision. Now refer to Figure 3D , Figure 3D An example of a predetermined pattern used to determine secondary boundary 314 is illustrated. Figure 3D The diagram shows Figure 3C The intensity map 330, the intensity curve 380 illustrating the variation of electron intensity along axis 365 in the intensity map 330, and the intensity curve 385 illustrating the variation of electron intensity along axis 370 in the intensity map 330. Axes 365 and 370 can be along adjacent rows of electron sensing elements on the sensor surface.

[0055] Figure 3DAlso illustrated are voltage decision curves 390 and 395, corresponding to intensity curve 380 and intensity curve 385, respectively. Voltage decision curves 390 and 395 represent comparisons of output voltages between adjacent electronic sensing elements along axes 365 and 370, respectively. Each voltage decision curve also shows switching of comparator decisions at certain points along each of axes 365 and 370, which can indicate changes in the polarity of the intensity gradient. For example, along axis 365, there is an increasing intensity before reaching a flat intensity region around the center of the beam spot at position B, followed by a decreasing intensity. Accordingly, along intensity curve 380, there is an increasing intensity 381 associated with the increasing intensity along axis 365, a flat intensity 382 associated with the flat region at position B along axis 365, and a decreasing intensity 383 associated with the decreasing intensity along axis 365.

[0056] Referring to the corresponding voltage decision curve 390, the output voltage +1 corresponding to comparator decision 391 reflects the increased intensity 381 from intensity curve 380, and the output voltage -1 corresponding to comparator decision 393 reflects the decreased intensity 383 from intensity curve 380. The voltage comparator decision 392 corresponding to intensity 382 can exhibit more switching between +1 and -1, possibly due to the difference in signal level from the electron intensity output of the processing system, which corresponds to the electron current intensity received by the adjacent electron sensing element and is below the noise level. Therefore, comparator decision 392 may be susceptible to random noise and can switch in either manner.

[0057] On the other hand, along axis 370, there is a relatively abrupt transition in intensity gradient, and the switching occurs at a position in the middle of axis 370 (labeled "C"). Based on the differences in the switching positions between adjacent rows (and columns), the processing system can determine a set of positions on the sensor surface that constitute the secondary boundary 314. For example, the processing system can determine that positions B and C are parts of the secondary boundary 314.

[0058] In some embodiments, the processing system can also improve the fidelity of image reconstruction by using boundary information to compensate for the effects of noise signals. As discussed above, the fidelity of image reconstruction can be reduced by noise signals generated by the electronic detection device 244 and not emitted by the wafer, resulting from scattered primary or secondary electrons. For example, these noise signals may include dark currents that can be generated without receiving any electrons. These noise signals may appear at electronic sensing elements located within the beam spot and at electronic sensing elements located outside the beam spot. The noise signals may be random noise signals that are independent in each electronic sensing element, or the noise signals may be system noise signals that have similar patterns and the same or different amplitudes in a region of the detector or in each sensing element of the entire detector. Using embodiments of the present disclosure, the processing system can exclude signals received from the output of electronic sensing elements located outside the primary boundary 312. This can improve the fidelity of image reconstruction by eliminating random noise signals from electronic sensing elements outside the primary boundary 312. Further, in some embodiments, the processing system can obtain a value representing the noise signal from the output of electronic sensing elements located outside the primary boundary 312. After generating an intensity value from the output of the electronic sensing element located within the primary boundary 312, the processing system can subtract a value representing a noise signal component from the intensity value. By removing or reducing the system noise signal component present in the intensity value, the fidelity of the image reconstruction can be improved.

[0059] Now refer to Figure 4A , Figure 4A The illustration shows a set of intensity maps 400 corresponding to four beams formed on the sensor surface. Based on voltage comparator decisions associated with the intensity maps, the processing system can obtain primary boundaries 312a, 312b, 312c, and 312d for each beam. The processing system can sum the outputs of the electronic sensing elements surrounded by each primary boundary 312a, 312b, 312c, and 312d to obtain the intensity value of each beam. Moreover, based on these primary boundaries, the processing system can also identify a set of electronic sensing elements outside these primary boundaries, including, for example, 402a, 402b, 402c, 402d, and 402e.

[0060] Due to interference sources near the detector, the processing system can obtain the output of the electronic sensing element (or idle electronic sensing element) outside the primary boundary (e.g., electronic sensing element 402a) as a representation of the noise signal. In some embodiments, the processing system can average these outputs to obtain a value representing the noise signal and subtract that value from the intensity value of each beam spot. In some embodiments, the processing system can also associate idle electronic sensing elements located outside the primary boundary of the beam spot based on their location and perform subtraction on the beam spot based on the noise signal from one or more associated idle electronic sensing elements. As an illustrative example, in Figure 4A In the example shown, the processing system can selectively subtract the noise signal of the electronic sensing elements 402b, 402c and 402e (but not the electronic sensing elements 402a and 402d) from the beam spot surrounded by the primary boundary 312c to remove the noise component and generate a compensation intensity value for the beam spot.

[0061] The processing system can also use boundary information to mitigate or eliminate noise signals caused by crosstalk. As discussed above, crosstalk can occur along with partial overlap of beam spots formed by adjacent electron beams due to aberrations and dispersion. In some embodiments, the processing system can base its processing on the primary boundary 312 of the adjacent beam spots (e.g., as shown in the diagram). Figure 4B (As shown) to detect partial overlap. Further, in some embodiments, the processing system may also include a secondary boundary 314 of adjacent beam spots when detecting partial overlap. Based on the detection, the processing system can determine that some electronic sensing elements are located in the region of beam spot overlap and exclude the outputs from these electronic sensing elements when determining the intensity value of the beam spots. Therefore, the need for anomaly correction hardware in the electro-optics subsystem can be relaxed or even eliminated to reduce or eliminate overlap between adjacent beam spots due to dispersion. Therefore, the complexity of the electron beam tool 104 can be reduced, which can improve the tool's performance and reliability. Furthermore, the anomaly correction hardware in the electro-optics subsystem can cause a significant reduction in the intensity of the detected electron beam and a decrease in the signal-to-noise ratio. Crosstalk determination and mitigation provided by the processing system can be used to adjust the balance between the signal-to-noise ratio and crosstalk in real time. The ability to adjust the balance between the signal-to-noise ratio and crosstalk in real time can greatly improve the flexibility and performance of the electron beam tool.

[0062] Now refer to Figure 4B , Figure 4B The illustration shows the intensity mapping 410 corresponding to the two partially overlapping beam spots. In this example, the processing system determines the primary boundary 312e (represented by solid lines) for the left beam spot and the primary boundary 312f (represented by dashed lines) for the right beam spot. The processing system also determines the secondary boundary 314e (represented by solid lines) for the left beam spot and the secondary boundary 314f (represented by dashed lines) for the right beam spot.

[0063] There are multiple ways a processing system can detect partial overlap between two beam spots. For example, the processing system can determine the distance 412 between the primary boundary 312e and the secondary boundary 314e of the left beam spot, and the distance 414 between the secondary boundary 314e of the left beam spot and the primary boundary 312f of the right beam spot. Based on the determination that distance 414 is shorter than distance 412, the processing system can determine that a portion of the primary boundary 312f of the right beam spot encroaches on the primary boundary 312e of the left beam spot. Based on the determination of encroachment, the processing system can determine that the two beam spots partially overlap.

[0064] As another example, the processing system can determine the distance 416 between the centers of the two beam spots based on secondary boundaries 314e and 314f. Based on the determination that the distance 416 falls below a predetermined threshold, the processing system can determine that the two beam spots partially overlap. For example, the threshold can be determined based on the estimated radius of the beam spots, such as the distance between the primary boundary 312e and the center of the left beam spot, the distance between the primary boundary 312f and the center of the right beam spot, or a combination of both. The processing system can then determine the region 420 where the overlap occurs and exclude the output of electronic sensing elements located within region 420 based on the intensity values ​​of the two beam spots.

[0065] While excluding the output of the electronic sensing element located within region 420 reduces noise due to crosstalk, this exclusion also reduces the intensity value generated for the beamspot. Therefore, beamspots emanating from the same wafer structure can have different intensity values. This difference can lead to distortion in the representation of the wafer structure utilizing the intensity values. In some embodiments, to mitigate the effects of distortion, the processing system can determine a scaling factor for the primary boundaries of all beamspots on the sensor surface, wherein the scaling factor is determined such that the updated primary boundary 312ee (scaled from primary boundary 312e) and the updated primary boundary 312ff (scaled from primary boundary 312f) no longer overlap at region 420.

[0066] The shrinkage factor can be determined based on various considerations. For example, the shrinkage factor can be based on the ratio between 412 and 416. Moreover, as discussed above, by excluding more outputs from the electronic sensing elements from the generation of beam spot intensity values, the generated intensity values ​​will be reduced. This reduction can decrease the intensity values ​​relative to noise components (e.g., from dark current, interference sources, etc.), resulting in a lower signal-to-noise ratio. With a reduced signal-to-noise ratio, the intensity distribution generated from the beam spot may become more susceptible to noise signals, which can reduce the fidelity of image reconstruction. Therefore, a shrinkage factor can also be determined such that the resulting signal-to-noise ratio is equal to or exceeds a predetermined threshold. Using this arrangement, the intensity values ​​of all beam spots can be scaled with the same scaling factor to avoid distortion, while also removing or reducing crosstalk noise signals. Furthermore, the same electronic detection device 244 can be used in electron beam tools that include different numbers of detected beam spots. The processing system can update the beam spot boundaries to detect different beam spots.

[0067] In some embodiments, the processing system may also use boundary information to mitigate the effects of other noise sources. For example, such as Figure 4C As shown, the processing system can determine that the electronic sensing element 435 has malfunctioned based on the low intensity of its output, and that the element is located within the primary boundary 312g. Based on this determination, the processing system can exclude the output of the electronic sensing element 435 from the intensity values ​​of the beam spot surrounded by the primary boundary 312g.

[0068] Now refer to Figure 5A , Figure 5A An exemplary processing system 500 for processing the output of an electronic detector according to an embodiment of the present disclosure is illustrated. The processing system 500 may be... Figure 2 The electron beam tool 104 is part of or coupled to it. The processing system 500 can receive generated electrical signals from multiple electronic sensing elements of the electron detection device 244, determine the intensity value of each of one or more detected electron beam spots, and reconstruct an image of the wafer based on the intensity values. For example... Figure 5A As shown, system 500 may include ( Figure 2 The system includes an electronic detection device 244, a preprocessing circuit 501, a signal processing circuit 502, an electron intensity determination circuit 503, a beamspot imaging circuit 504, and a beamspot processing module 506. The beamspot processing module 506 may further include a beamspot boundary determination module 508, an intensity threshold module 509, a beamspot intensity determination module 510, an image reconstruction module 512, and a beamspot imaging module 515.

[0069] Generally, the term "module" as used herein can refer to an encapsulated functional hardware unit designed for use with other components (e.g., portions of an integrated circuit) and / or a part of a program (stored on a computer-readable medium) that perform a specific function in a related function. A module may have entry and exit points and may be written in a programming language (such as, for example, Java, Lua, C, or C++). Software modules may be compiled and linked into an executable program, installed in a dynamic link library, or written in an interpreted programming language (such as, for example, BASIC, Perl, or Python). It is to be understood that software modules can be called from other modules or from themselves, and / or may be invoked in response to detected events or interrupts. Software modules configured for execution on a computing device may be set on a computer-readable medium (such as a compressed disk, digital video disk, flash drive, hard disk, or any other non-transitory medium) or provided as a digital download (and may initially be stored in a compressed or installable format that requires installation, decompression, or decryption before execution). Such software code may be stored partially or entirely on a memory device executing the computing device for execution by the computing device. Software instructions can be embedded in firmware, such as erasable programmable read-only memory (EPROM). To further understand, hardware modules can be composed of interconnected logical units (such as gates and flip-flops) and / or can be composed of programmable units (such as programmable gate arrays or processors). The modules or computing device functions described herein are preferably implemented as software modules, but can be represented in hardware or firmware. Generally, the modules described herein refer to logical modules that can be combined with other modules or divided into submodules, regardless of their physical organization or storage.

[0070] The preprocessing circuit 501 can process the output of the electronic sensing elements of the electronic detection device 244 to generate an intensity signal representing the intensity of the electrons received by each electronic sensing element. Now refer to... Figure 5B , Figure 5B The illustration shows exemplary components of the preprocessing circuit 501, the signal processing circuit 502, the electron intensity determination circuit 503, and the beam spot imaging circuit 504. Figure 5B As shown, the preprocessing circuit 501 may include signal conditioning circuits 501a, 501b, ... 501c coupled to the corresponding electronic sensing elements 520a, 520b, ... 502c of the electronic detection device 244. For example, each signal conditioning circuit 501a, 501b, ... 501c may include an amplifier, an amplifier input protection circuit, etc., configured to amplify and filter the output of each electronic sensing element 520a, 520b, ... 520c. The preprocessing circuit 501 can then transmit the amplified and filtered voltage as an intensity signal to the signal processing circuit 502.

[0071] Now refer to Figure 5C , Figure 5C An exemplary component of the signal processing circuit 502 is illustrated. For example... Figure 5C As shown, the signal processing circuit 502 may include a signal threshold circuit 505, an intensity gradient determination circuit 507, a reference voltage generation circuit 502g, a signal switching matrix 502h, and a peak detection circuit (not shown in the diagram). Figure 5C (shown in) and analog-to-digital converter (not shown in) Figure 5C (As shown in the image).

[0072] In some embodiments, the signal thresholding circuit 505 may include voltage comparators 502d, 502e, and 502f. Voltage comparators 502d, 502e, and 502f may be configured to compare the instantaneous signal voltages of signals from signal conditioning circuits 501a, 501b, and 501c with the voltage from reference voltage generation circuit 502g. The outputs of voltage comparators 502d, 502e, and 502f may be forwarded to the intensity thresholding module 509. The reference voltage generated by the reference voltage generation circuit 502g may be a predetermined intensity threshold. Any pre-processed intensity signal below the predetermined intensity threshold may be attributed to an electronic sensing element with no beam signal output and may be used to estimate the noise signal level.

[0073] In other embodiments, instead of using a voltage comparator, the signal threshold circuit 505 may include an analog-to-digital converter with a bit resolution greater than one bit, thereby allowing the ability to provide more detailed information about the magnitude of the signal level. For example, instead of merely indicating whether the signal level is above or below a predetermined strength threshold, the output of the signal threshold circuit 505 may indicate the range by which the signal level is above or below the threshold.

[0074] In some embodiments, the intensity gradient determination circuit 507 may include voltage comparators 502a, 502b, and 502c. The voltage comparators 502a, 502b, and 502c may be configured to compare intensity signals output by a nearby electronic sensing element. The comparators may generate a set of comparator decisions (e.g., as depicted in voltage decision graphs 360, 390, and 395) to provide an indication of changes in the intensity gradient. For example, referring to… Figure 5B and Figure 5CComparator 502a is configured to compare preprocessed intensity signals from 501a and 501b corresponding to signals generated from neighboring electronic sensing elements 520a and 520b. Comparator 502b is configured to compare preprocessed intensity signals from 501b and 501c corresponding to signals generated from neighboring electronic sensing elements 520b and 520c. Further, comparator 502c is configured to compare preprocessed intensity signals from 501a and 501c corresponding to signals generated from neighboring electronic sensing elements 520a and 520c. The intensity gradient determination circuit 507 can forward the comparator decision and the position of the electronic sensing element corresponding to the comparator decision (which can be represented as two-dimensional coordinates) to the beam spot boundary determination module 508 of the beam spot processing module 506.

[0075] In other embodiments, instead of using a voltage comparator, the intensity gradient determination circuit 507 may include an analog-to-digital converter (ADC) with a bit resolution greater than one bit. By using such an ADC, the intensity gradient determination circuit 507 can provide gradients with higher resolution.

[0076] The beam spot boundary determination module 508 can process comparator decisions and the positional information associated with those decisions, and determine the primary boundary 312 and secondary boundary 314 of the beam spot. For example, the boundary determination can be based on detecting a predetermined pattern in the comparator decision, as described above relative to... Figure 3C and Figure 3D As described. For example, the beam spot boundary determination module 508 can also update the determined boundary based on the detection of partial overlap between neighboring beam spots, as shown below relative to Figure 4B As described.

[0077] In some embodiments, the signal processing circuit 502 may not include the intensity gradient determination circuit 507. The beam spot boundary determination module 508 may determine primary and secondary beam boundaries (e.g., primary boundary 312 and secondary boundary 314) based on input from the beam spot imaging module 515. The beam spot boundary determination module 508 may include an image processing algorithm to determine primary and secondary beam boundaries based on the beam spot image provided by the beam spot imaging module 515. Further, the beam spot boundary determination module 508 may include an image processing algorithm to determine partial overlap between adjacent beam spots (e.g., ...) based on the beam spot image provided by the beam spot imaging module 515. Figure 4B Region 420). The beam spot boundary determination module 508 can provide a set of positions (represented as two-dimensional coordinates) representing the primary boundary 312 and the secondary boundary 314 to the signal switching matrix 502h.

[0078] The signal switching matrix 502h can group the preprocessed intensity signals received from the signal conditioning circuits 510a, 510b, and 510c. Grouping can be performed based on beam spot boundary information sent from the beam spot boundary determination module 508, resulting in groups of electronic signals corresponding to the groups of electronic sensing elements. The signal switching matrix 502h may include a set of multiplexers configured to select which preprocessed intensity signal corresponding to the electronic sensing elements 520a, 520b, and 520c should be forwarded to the electronic intensity determination circuit 503. For example, the signal switching matrix 502h can exclude one or more outputs corresponding to the electronic sensing elements 520a, 520b, and 520c based on determining that the electronic sensing elements are located outside the primary boundary. Each group of electronic signals can be transmitted to the electronic intensity determination circuit 503. The electronic intensity determination circuit 503 can generate an electronic signal representing the overall intensity of the corresponding portion of the electron beam.

[0079] In some embodiments, the signal switching matrix 502h can also be configured to scan signals from preprocessed intensity signals from signal conditioning circuits 501a to 501c and forward the scanned signals to the beamspot imaging circuit 504. The signal switching matrix 502h can implement the scanning process by selecting which received inputs to forward to the beamspot imaging circuit 504. The scanning rate can be controlled by the beamspot processing module 506. For example, the preprocessed signals corresponding to the electronic sensing elements can be scanned sequentially (one at a time), or the preprocessed signals corresponding to multiple electronic sensing elements can be scanned simultaneously (e.g., signals corresponding to one electronic sensing element per row of sensor surface 300 can be scanned simultaneously). Further, the scanning area can also be controlled by the beamspot processing module 506. For example, refer to... Figure 3A The switch matrix 502h can be configured to scan only the preprocessed signal corresponding to the electronic sensing element of the sensor region 302A, and not scan the preprocessed signal corresponding to the electronic sensing element of the sensor region 302D.

[0080] In some embodiments, the peak detection circuit of the signal processing circuit 502 may be configured to determine the minimum and maximum voltage levels of the signals from each of the signal conditioning circuits 501a, 501b, and 501c. Further, the analog-to-digital converter of the signal processing circuit 502 may be configured to digitize the peak signals and forward the digitized signals to the beam spot processing module 506, which may communicate with external components (e.g., a controller or data storage library) via a bus (not shown).

[0081] Refer to the return Figure 5BThe electron intensity determination circuit 503 may include: summing amplifiers 521a, 521b, ... 521c; post-signal conditioning circuits 522a, 522b, ... 522c; and analog-to-digital converters 523a, 523b, ... 523c. The summing amplifiers 521a, 521b, ... 521c may be configured to receive grouped electron signals transmitted from the signal switch matrix 502h. The summing amplifiers 521a, 521b, ... 521c may be configured to sum the outputs of some or all of the signal conditioning circuits 501a, 501b, ... 501c and provide a summed signal representing the overall intensity of the corresponding portion of the electron beam. The post-signal conditioning circuits 522a, 522b, ... 522c may include a variable gain amplifier (VGA) and an offset voltage generation circuit. The variable gain amplifier may amplify the summed signal output from the summing amplifiers 521a, 521b, ... 521c. A variable gain amplifier can modify the contrast of the reconstructed wafer image and increase the dynamic range of the image channels. An offset voltage generation circuit can be configured to add an offset voltage to the amplified signal from the VGA to adjust the brightness of the reconstructed wafer image. The amplifier gain and offset voltage of the post-signal conditioning circuits 522a, 522b, ... 522c can be controlled by the beam spot processing module 506. Analog-to-digital converters 523a, 523b, ... 523c can be configured to convert the analog signal provided by the post-signal conditioning circuits 522a, 522b, ... 522c into a set of digital signals and provide the digital signals to the beam spot intensity determination module 510. The digital signals can correspond to the sum of the intensities of a portion of the beam spot. In some embodiments, the electronic intensity determination circuit 503 may include an additional summing amplifier, offset correction circuit, variable gain amplifier, and analog-to-digital converter to generate noise measurements via an electronic sensing element determined to be outside the primary boundary and to provide the noise measurements to the beam spot intensity determination module 510.

[0082] The beam spot intensity determination module 510 can receive digital values ​​from the electronic intensity determination circuit 503 and perform additional post-processing. For example, post-processing may include further summing of the digital values ​​to generate the intensity value of the beam spot. The electronic intensity determination circuit 503 may also perform post-processing to mitigate the effects of noise, such as detecting and excluding the intensity output from a malfunctioning electronic sensing element, detecting and excluding the intensity output from an electronic sensing element located in an overlapping region between adjacent beam spots, etc. The beam spot intensity determination module 510 may also perform other post-processing to mitigate the effects of noise, such as subtracting the noise measurement result from the intensity data. The beam spot boundary determination module 508 can determine the trajectory of the beam spot (e.g., based on secondary boundaries) and provide the trajectory information of the beam spot, along with the intensity value from the beam spot intensity determination module 510, to the image reconstruction module 512.

[0083] The image reconstruction module 512 can reconstruct an image of the wafer by combining the intensity values ​​collected within a time window with the scan path data of one or more primary electron beams during the time window. Therefore, an image of the wafer under study can be acquired.

[0084] like Figure 5B As shown, the beamspot imaging circuit 504 may include: buffer amplifiers 531a, ... 531b; post-signal conditioning circuits 532a, ... 532b; and analog-to-digital converters 533a, ... 533b. The buffer amplifiers 531a, ... 531b may be configured to transmit the scanning electronic signal from the signal switching matrix 502h to the post-signal conditioning circuits 532a, ... 532b. The post-signal conditioning circuits 532a, ... 532b may include a variable gain amplifier (VGA) and an offset voltage generation circuit. The variable gain amplifier may amplify the output signal from the buffer amplifiers 531a, ... 531b. The variable gain amplifier may modify the contrast of the reconstructed beamspot image. The offset voltage generation circuit may be configured to add an offset voltage to the amplified signal from the VGA to adjust the brightness of the reconstructed beamspot image. The amplifier gain and offset settings of the post-signal conditioning circuits 532a, ... 532b may be controlled by the beamspot processing module 506. The analog-to-digital converters 533a, ... 533b can be configured to convert the analog signals provided by the post-signal conditioning circuits 532a, ... 532b into a set of digital signals and provide the digital signals to the beamspot imaging module 515.

[0085] Figure 6 This is a flowchart illustrating an exemplary method 600 for inspecting a wafer. It will be readily understood that the illustrated process can be modified to remove steps or further include additional steps. For example, method 600 can be... Figure 1 Electron beam tool 104 combined Figure 5A The system is running error 500.

[0086] Following initial startup, in step 602, a primary electron beam (e.g., sub-beams 214, 216, or 218) is projected onto a wafer (e.g., wafer 230). The primary electron beam can be emitted by an electron source 202. It is then guided by a bore 204, a condenser lens 206, and a source conversion unit 212 to form multiple sub-beams. One or more sub-beams of the primary electron beam are provided to a primary projection optics system 220, which can focus one or more sub-beams onto wafer 230 and can guide secondary or backscattered electrons to an electron detector.

[0087] In step 604, an electron detector (e.g., electron detection device 244) can detect one or more electron beams (e.g., electron beams 236, 238, and 240) emitted or scattered by the wafer, including secondary or backscattered electrons. The detector may include a plurality of electron sensing elements configured to generate a signal based on a number of electrons received by the electron sensing elements within a predetermined time period.

[0088] In step 606, the beam spot boundary determination module 508 can determine the boundary of the beam spot formed by the electron beam detected in step 604. The boundary determination can be based on the intensity gradient information of the beam spot provided by the signal processing circuit 502.

[0089] In step 608, the beam spot boundary determination module 508 can determine, based on the determined boundary, a first set of electronic sensing elements located within the boundary and a second set of electronic sensing elements located outside the boundary. This determination can be based on the position of a set of electronic sensing elements on the sensor surface of the electronic detection device 244 and the position information of the boundary.

[0090] In step 610, the electron intensity determination circuit 503 can determine the intensity value of the beam spot based on the output from the first set of electronic sensing elements. For example, the system can sum the output from the first set of electronic sensing elements, perform brightness correction, perform contrast adjustment, and convert the resulting analog signals into digital signals.

[0091] In step 612, the electron intensity determination circuit 503 can also determine the noise component based on the output from the second set of electronic sensing elements. For example, the system can obtain the output of the electronic sensing elements outside the boundary of the beam spot but within a predetermined distance from the boundary as a measurement result of the noise signal caused by an interference source located near the detector, etc.

[0092] In step 614, the beam spot intensity determination module 510 can subtract the noise component (both of which can be provided by the electronic intensity determination circuit 503) from the intensity value to perform noise compensation. In some embodiments, the electronic intensity determination circuit 503 can use the beam spot boundary determined in step 606 to eliminate crosstalk between adjacent beam spots, as shown in reference Figure 4B As described. In step 614, the beam spot intensity determination module 510 can subtract the crosstalk component (both of which can be provided by the electronic intensity determination circuit 503) from the intensity value to perform noise compensation.

[0093] In step 616, based on the compensated electron intensity information, the image reconstruction module 512 can reconstruct an image of the wafer. The image reconstruction module 512 can reconstruct an image of the wafer by combining the intensity values ​​provided by the beam intensity determination module 510 within a time window and the scan path data of one or more primary electron beams during the time window.

[0094] Figure 7 This is a flowchart illustrating an exemplary method 700 for inspecting a wafer using multiple beams. It will be readily understood that the illustrated process can be modified to remove steps or further include additional steps. For example, method 700 can be... Figure 1 Electron beam tool 104 combined Figure 5A The system is running error 500.

[0095] Following initial startup, in step 702, two or more sub-beams of the primary electron beam (e.g., sub-beams 214, 216, and / or 218) are projected onto a wafer (e.g., wafer 230). The primary electron beam can be emitted by electron source 202. The primary electron beam is then guided by aperture 204, condenser lens 206, and source conversion unit 212 to form multiple sub-beams of the primary electron beam. Two or more sub-beams of the primary electron beam are provided to primary projection optics system 220, which can focus the two or more sub-beams onto wafer 230 and can guide secondary or backscattered electrons to an electron detector.

[0096] In step 704, the electron detector (e.g., electron detection device 244) can detect multiple electron beams (e.g., secondary electron beams 236, 238, and 240) emitted or scattered by the wafer, including secondary or backscattered electrons. The detector may include multiple electron sensing elements configured to generate a signal based on a number of electrons received by the electron sensing elements within a predetermined time period.

[0097] In step 706, the beam spot boundary determination module 508 can determine the first boundary of the first beam spot and the second boundary of the second beam spot formed by the electron beam detected in step 704. The boundary determination can be based on the intensity gradient information of the beam spot provided by the signal processing circuit 502.

[0098] In step 708, the beam spot boundary determination module 508 can determine a first set of electronic sensing elements located within the first boundary and a second set of electronic sensing elements located within the second boundary based on the determined boundaries. This determination can be based on the position of a set of electronic sensing elements on the sensor surface of the electronic detection device 244 and the position information of the boundaries.

[0099] In step 710, the beam spot processing module 506 can also determine the overlap region between the first and second beam spots based on the electronic sensing element shared by the first and second beam spots. For example, the beam spot processing module 506 can detect the overlap region 420, as shown in reference... Figure 4B As described. In some embodiments, the beam spot processing module 506 can determine a third boundary surrounding the center of the first beam spot, a first distance between the third boundary and the first boundary, and a second distance between the third boundary and the second boundary. For example, refer to Figure 4B The beam spot processing module 506 can determine a first distance 412 and a second distance 414. In some embodiments, the beam spot processing module 506 can determine the distance between the centers of the two beam spots based on third and fourth boundaries. For example, the beam spot processing module can determine a distance 416 between the centers of the two beam spots, as shown in reference... Figure 4B As described. If the defined distance between the centers falls below a predetermined threshold, the beam spot processing module 506 can further determine the overlapping region. For example, refer to... Figure 4B The beam spot processing module 506 can determine the overlapping region 420 based on the distance 416 being lower than a predetermined threshold.

[0100] The beam speckle processing module 506 can mitigate the impact of overlapping regions by shrinking the beam speckle boundaries. In step 712, the beam speckle processing module 506 can determine updated first and second boundaries based on the determined overlapping regions. For example, referring to… Figure 4B The beamspot processing module 506 can determine updated first boundaries 312ee and updated second boundaries 312ff. A shrinkage factor can be determined based on various considerations. In some embodiments, the shrinkage factor can be based on the ratio between a first distance and a second distance between the centers determined in step 710. Further, excluding the output from the electronic sensing elements in the determined overlapping region can reduce the determined intensity value of the beamspot. This reduction can decrease the intensity value relative to noise components (e.g., from dark current, interference sources, etc.), resulting in a lower signal-to-noise ratio. With a reduced signal-to-noise ratio, the intensity distribution generated from the beamspot may become more susceptible to noise signals, which can reduce the fidelity of image reconstruction. Therefore, in some embodiments, a shrinkage factor can also be determined such that the resulting signal-to-noise ratio is equal to or exceeds a predetermined threshold.

[0101] In step 714, the beamspot processing module 506 can determine the intensity value of the beamspot based on the updated boundary. This can reduce or eliminate crosstalk between adjacent beamspots, as shown in the reference. Figure 4B As described.

[0102] In step 716, the beamspot processing module 506 can reconstruct an image of the wafer based on the determined intensity values ​​of the beamspot. The beamspot processing module 506 can reconstruct an image of the wafer by combining the intensity values ​​provided by the electronic sensing elements within the updated first and second boundaries.

[0103] The embodiments may be further described using the following terms:

[0104] 1. A detection system, comprising:

[0105] The signal processing circuit is configured to generate a set of intensity gradients based on electron intensity data received from multiple electronic sensing elements; and

[0106] The beam spot processing module is configured as follows:

[0107] At least one boundary of the beam spot is determined based on the set of intensity gradients; and

[0108] The first group of electronic sensing elements among the plurality of electronic sensing elements is determined within the beam spot based on the at least one boundary.

[0109] 2. A detection system, comprising:

[0110] Beam spot processing module, the beam spot processing module being configured to:

[0111] A set of intensity signals is acquired from multiple electronic sensing elements;

[0112] At least one boundary of the beam spot is determined based on the set of intensity signals; and

[0113] The first group of electronic sensing elements among the plurality of electronic sensing elements is determined within the beam spot based on the at least one boundary.

[0114] 3. The detection system according to clause 1 or 2, wherein the beam spot processing module is further configured to:

[0115] The intensity value of the beam spot is determined based on the electron intensity data received from the first set of electronic sensing elements.

[0116] 4. The detection system according to Clause 3, wherein the speckle processing module is further configured to generate an image of the wafer based on the intensity value.

[0117] 5. The detection system according to any one of clauses 1, 3 and 4, wherein the signal processing circuitry includes an intensity gradient determination circuit configured to generate the set of intensity gradients.

[0118] 6. The detection system according to Clause 5, wherein the intensity gradient determination circuit includes a set of comparators configured to:

[0119] A set of comparison decisions is generated based on the comparison of electron intensity data from adjacent electron sensing elements among the plurality of electron sensing elements, wherein the set of intensity gradients is determined based on the generated set of comparison decisions.

[0120] 7. The detection system according to any one of Clauses 1 to 6, wherein the beam spot processing module includes a beam spot boundary determination module configured to determine the at least one boundary of the beam spot.

[0121] 8. The detection system according to Clause 7, wherein the plurality of electronic sensing elements form a sensor surface; and wherein the determination of the at least one boundary of the beam spot includes the beam spot boundary determination module, the beam spot boundary determination module being further configured to:

[0122] The set of comparison decisions is associated with a set of locations on the sensor surface;

[0123] A first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and

[0124] The first position is determined to be part of the at least one boundary.

[0125] 9. The detection system according to Clause 8, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the beam spot boundary determination module is configured to determine the first position as a position between the first region and the second region.

[0126] 10. The detection system according to any one of clauses 1 to 9, wherein the beam spot processing module further includes a beam spot intensity determining module configured to determine the intensity value of the beam spot.

[0127] 11. The detection system according to Clause 10, wherein determining the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0128] The second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot based on the at least one boundary;

[0129] The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; and

[0130] The compensation intensity value is determined based on a combination of the intensity value determined by the electron intensity data from the first set of electronic sensing elements and the noise component.

[0131] The beam spot processing module is configured to generate the image of the wafer based on the compensation intensity value.

[0132] 12. The detection system according to Clause 11, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0133] Selecting one or more electronic sensing elements from the second set of electronic sensing elements based on the distance between the one or more electronic sensing elements and the at least one boundary; and

[0134] The noise component is determined based on the electron intensity data received from the selected one or more electronic sensing elements.

[0135] 13. The detection system according to any one of clauses 1 to 12, wherein the speckle processing module further includes an image reconstruction module configured to generate the image of the wafer based on the intensity value.

[0136] 14. A detection system, comprising:

[0137] The signal processing circuit is configured to generate a set of intensity gradients based on electron intensity data received from multiple electronic sensing elements; and

[0138] The beam spot processing module is configured as follows:

[0139] The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients.

[0140] Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot;

[0141] Based on the second boundary, the second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot; and

[0142] The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

[0143] 15. A detection system, comprising:

[0144] The beam spot processing module is configured as follows:

[0145] A set of intensity signals is acquired from multiple electronic sensing elements;

[0146] The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity signals.

[0147] Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot;

[0148] Based on the second boundary, the second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot; and

[0149] The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

[0150] 16. The detection system according to Clause 14 or 15, wherein the beam spot processing module includes a beam spot boundary determination module configured to determine the first boundary and the second boundary.

[0151] 17. The detection system according to any one of clauses 14 to 16, wherein determining the intensity value of at least one of the first and second beamspots includes the beamspot processing module being further configured to:

[0152] Determine the third group of electronic sensing elements among the plurality of electronic sensing elements within the overlapping region; and

[0153] A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein electronic intensity data received from the third set of electronic sensing elements are excluded.

[0154] 18. The detection system according to Clause 17, wherein the beam spot processing module further includes a beam spot intensity determination module configured to determine the first intensity value and the second intensity value.

[0155] 19. The detection system according to any one of clauses 14 to 18, wherein the speckle processing module is further configured to determine at least one of an updated first boundary and an updated second boundary based on the overlapping region.

[0156] The beam spot processing module is configured to determine a first intensity value of the first beam spot or a second intensity value of the second beam spot based on at least one of the updated first boundary and the updated second boundary.

[0157] 20. The detection system according to Clause 19, wherein determining at least one of the updated first boundary and the updated second boundary based on the overlapping region includes the beamspotting module being further configured to:

[0158] Determine the third boundary surrounding the center of the first beam spot;

[0159] Determine the first distance between the third boundary and the first boundary;

[0160] Determine the second distance between the third boundary and the second boundary;

[0161] A scaling factor is determined based on the first distance and the second distance; and

[0162] At least one of the updated first boundary and the updated second boundary is determined based on the scaling factor.

[0163] 21. The detection system according to Clause 20, wherein the scaling factor is determined based on a predetermined signal-to-noise ratio threshold.

[0164] 22. The detection system according to any one of clauses 17 to 21, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0165] Based on electron intensity data received from the one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; and

[0166] The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

[0167] 23. The detection system according to any one of clauses 14 to 22, further comprising an electron intensity determination circuit, said electron intensity determination circuit being configured to:

[0168] Generate the sum of the electron intensity data received from the first set of electron sensing elements, and

[0169] Generate a digital signal representing the sum;

[0170] The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on the digital signal.

[0171] 24. The detection system according to Clause 23, wherein the electron intensity determining circuit further comprises:

[0172] A summing amplifier configured to output a summing signal representing the sum based on electron intensity data selected by a signal switching matrix, wherein the signal switching matrix is ​​configured to select the electron intensity data of the first set of electron sensing elements based on the at least one boundary;

[0173] Post-signal conditioning circuit, the post-signal conditioning circuit comprising:

[0174] A variable gain amplifier is configured to amplify the summing signal from the summing amplifier; and

[0175] An offset voltage generation circuit is configured to add an offset voltage to the amplified signal from the variable gain amplifier; and

[0176] An analog-to-digital converter is configured to generate the digital signal based on the signal from the post-signal conditioning circuit.

[0177] 25. The detection system according to any one of clauses 1 to 24, wherein generating an image of the wafer based on the intensity value includes the image reconstruction module further configured to:

[0178] The intensity values ​​of the plurality of beam spots are obtained from the beam spot intensity determination module;

[0179] The trajectories of the plurality of beam spots are obtained from the beam spot boundary determination module;

[0180] Mapping the trajectory to multiple scan locations on or within the wafer; and

[0181] The image of the wafer is constructed based on the intensity value and the scanning position.

[0182] 26. The detection system according to any one of clauses 1 to 25, further comprising a beamspot imaging circuit, said beamspot imaging circuit being configured to:

[0183] Signals representing electron intensity data are received from one or more electronic sensing elements scanned by the signal switching matrix;

[0184] Generate a digital signal representing the amplitude of the signal; and

[0185] The digital signal is provided to a beamspot imaging module, wherein the beamspot imaging module is configured to generate an image of the beamspot.

[0186] 27. The detection system according to any one of clauses 1 to 26 further includes a set of signal conditioning circuitry configured to preprocess electron intensity data received from each of the plurality of electron sensing elements;

[0187] The intensity gradient determination circuit is configured to determine a set of intensity gradients based on preprocessed electron intensity data; and

[0188] The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on preprocessed electron intensity data.

[0189] 28. An electronic detection system, comprising:

[0190] Multiple electronic sensing elements are configured to receive at least one electron beam, comprising backscattered electrons or secondary electrons, from a wafer; and

[0191] Processing system, the processing system comprising:

[0192] An intensity gradient determination circuit is configured to determine a set of intensity gradients based on electron intensity data received from each of the plurality of electronic sensing elements.

[0193] Beam spot boundary determination module, wherein the beam spot boundary determination module is configured to:

[0194] Based on the set of intensity gradients, at least one boundary of the beam spot of one of the at least one electron beams is determined, and

[0195] Based on the at least one boundary, a first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the beam spot; and

[0196] A beam spot intensity determination module, configured to determine the intensity value of the beam spot based on the electron intensity data received from the first set of electronic sensing elements; and

[0197] An image reconstruction module is configured to generate an image of the wafer based on the intensity value.

[0198] 29. The electronic detection system according to Clause 28, wherein the intensity gradient determination circuit includes a set of comparators configured to compare the electron intensity data received from a pair of adjacent electronic sensing elements among the plurality of electronic sensing elements;

[0199] The set of intensity gradients is determined based on a set of comparison decisions made by the set of comparators.

[0200] 30. The electronic detection system according to Clause 29, wherein the plurality of electronic sensing elements form a sensor surface; wherein the determination of at least one boundary of the beam spot includes the beam spot boundary determination module being configured to:

[0201] The set of comparison decisions is associated with a set of locations on the sensor surface;

[0202] The first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and

[0203] The first position is determined to be part of the at least one boundary.

[0204] 31. The electronic detection system according to Clause 30, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the beam spot boundary determination module is configured to determine the first position as a position between the first region and the second region.

[0205] 32. The electronic detection system according to any one of clauses 28 to 31, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0206] The second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot based on the at least one boundary;

[0207] The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; and

[0208] The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component.

[0209] The image reconstruction module is configured to generate the image of the wafer based on the compensation intensity value.

[0210] 33. The electronic detection system according to clause 32, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0211] Selecting one or more electronic sensing elements from the second set of electronic sensing elements based on the distance between the one or more electronic sensing elements and the at least one boundary; and

[0212] The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

[0213] 34. The electronic detection system according to any one of clauses 28 to 33, wherein the determination of at least one boundary of the beam spot includes the beam spot boundary determination module being configured to:

[0214] The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients.

[0215] The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

[0216] 35. The electronic detection system according to clause 34, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0217] Determine the third group of electronic sensing elements among the plurality of electronic sensing elements within the overlapping region; and

[0218] A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

[0219] 36. The electronic detection system according to clause 34 or 35, wherein the beam spot boundary determination module is further configured to determine an updated first boundary and an updated second boundary based on the overlapping region.

[0220] The beam spot intensity determination module is configured to determine a first intensity value of the first beam spot and a second intensity value of the second beam spot based on the updated first boundary and the updated second boundary, respectively.

[0221] 37. The electronic inspection system according to Clause 36, wherein the determination of the updated first boundary and the updated second boundary based on the overlapping region includes the beam spot boundary determination module being further configured to:

[0222] Determine the third boundary surrounding the center of the first beam spot;

[0223] Determine the first distance between the third boundary and the first boundary;

[0224] Determine the second distance between the third boundary and the second boundary;

[0225] A scaling factor is determined based on the first distance and the second distance; and

[0226] The first boundary and the second boundary of the update are determined based on the scaling factor.

[0227] 38. The electronic detection system according to Clause 37, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

[0228] 39. The electronic detection system according to any one of clauses 28 to 38, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to:

[0229] Based on electron intensity data received from the one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; and

[0230] The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

[0231] 40. The electronic detection system according to any one of clauses 28 to 39, further comprising the electron intensity determining circuit configured as follows:

[0232] Generate the sum of the electron intensity data received from the first set of electron sensing elements, and

[0233] Generate a digital signal representing the sum;

[0234] The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on the digital signal.

[0235] 41. The electronic detection system according to Clause 40, wherein the electron intensity determination circuit comprises:

[0236] A summing amplifier is configured to output a summing signal representing the sum based on electron intensity data selected by a signal switching matrix, wherein the signal switching matrix is ​​configured to select the electron intensity data of the first set of electron sensing elements based on the at least one boundary.

[0237] Post-signal conditioning circuit, including:

[0238] A variable gain amplifier is configured to amplify the summing signal from the summing amplifier; and

[0239] An offset voltage generation circuit is configured to add an offset voltage to the amplified signal from the variable gain amplifier; and

[0240] An analog-to-digital converter is configured to generate the digital signal based on the signal from the post-signal conditioning circuit.

[0241] 42. The electronic inspection system according to any one of clauses 28 to 41, wherein generating an image of the wafer based on the intensity value includes the image reconstruction module being configured to:

[0242] The intensity values ​​of multiple beam spots are obtained from the beam spot intensity determination module;

[0243] The trajectories of the plurality of beam spots are obtained from the beam spot boundary determination module;

[0244] Mapping the trajectory to multiple scan locations on or within the wafer; and

[0245] The image of the wafer is constructed based on the intensity value and the scanning position.

[0246] 43. The electronic detection system according to any one of clauses 28 to 42, wherein the processing system further includes the beamspot imaging circuit configured as follows:

[0247] Signals representing electron intensity data are received from one or more electronic sensing elements scanned by the signal switching matrix;

[0248] Generate an amplified digital signal representing the signal; and

[0249] The digital signal is provided to a beamspot imaging module, wherein the beamspot imaging module is configured to generate an image of the beamspot.

[0250] 44. The electronic detection system according to any one of clauses 28 to 43, further comprising a set of signal conditioning circuitry configured to preprocess the electron intensity data received from each of the plurality of electronic sensing elements;

[0251] The intensity gradient determination circuit is configured to determine the set of intensity gradients based on preprocessed electron intensity data; and

[0252] The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on preprocessed electron intensity data.

[0253] 45. A method comprising:

[0254] A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements; and

[0255] At least one boundary of the beam spot is determined based on the set of intensity gradients.

[0256] 46. ​​The method described in accordance with Clause 45 further includes:

[0257] Based on the at least one boundary, a first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the beam spot.

[0258] 47. The method described in accordance with Clause 46 further includes:

[0259] The intensity value of the beam spot is determined based on the electron intensity data received from the first set of electronic sensing elements.

[0260] 48. The method described in accordance with Clause 47 further includes:

[0261] An image of the wafer is generated based on the intensity value.

[0262] 49. The method according to any one of clauses 45 to 48, further comprising:

[0263] A set of comparison decisions is generated by a set of signal level difference determination devices based on comparisons of electron intensity data from adjacent electron sensing elements among the plurality of electron sensing elements, wherein the set of intensity gradients is determined based on the generated set of comparison decisions.

[0264] 50. The method according to Clause 49, wherein the signal level difference determining device includes a voltage comparator.

[0265] 51. The method according to clause 49 or 50, wherein the plurality of electronic sensing elements form a sensor surface; wherein defining at least one boundary of the beam spot comprises:

[0266] The set of comparison decisions is associated with a set of locations on the sensor surface;

[0267] The first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and

[0268] The first position is determined to be part of the at least one boundary.

[0269] 52. The method according to Clause 51, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the first position is determined as a position between the first region and the second region.

[0270] 53. The method according to any one of clauses 47 to 52, wherein determining the intensity value of the beam spot further comprises:

[0271] Based on the at least one boundary, a second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot;

[0272] The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; and

[0273] The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component.

[0274] The image of the wafer is generated based on the compensation intensity value.

[0275] 54. The method according to Clause 53, wherein determining the intensity value of the beam spot comprises:

[0276] Selecting one or more electronic sensing elements from the second set of electronic sensing elements based on the distance between the one or more electronic sensing elements and the at least one boundary; and

[0277] The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

[0278] 55. A method comprising:

[0279] A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements;

[0280] The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients.

[0281] Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot;

[0282] Based on the second boundary, the second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot; and

[0283] The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

[0284] 56. The method according to Clause 55 further includes determining an intensity value for at least one of the first and second beamspots, wherein determining the intensity value further includes:

[0285] Determine the third group of electronic sensing elements among the plurality of electronic sensing elements within the overlapping region; and

[0286] A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

[0287] 57. The method described pursuant to Clause 55 or 56 further includes:

[0288] Based on the overlapping region, the updated first boundary and the updated second boundary are determined; and

[0289] The first intensity value of the first beam spot and the second intensity value of the second beam spot are determined based on the updated first boundary and the updated second boundary, respectively.

[0290] 58. The method according to Clause 57, wherein determining the updated first boundary and the updated second boundary based on the overlapping region comprises:

[0291] Determine the third boundary surrounding the center of the first beam spot;

[0292] Determine the first distance between the third boundary and the first boundary;

[0293] Determine the second distance between the third boundary and the second boundary;

[0294] A scaling factor is determined based on the first distance and the second distance; and

[0295] The first boundary and the second boundary of the update are determined based on the scaling factor.

[0296] 59. The method according to Clause 58, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

[0297] 60. The method according to any one of clauses 47 to 59, wherein determining the intensity value of the beam spot comprises:

[0298] Based on the electron intensity data received from the one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; and

[0299] The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

[0300] 61. The method according to any one of clauses 47 to 60, further comprising:

[0301] Generate the sum of the electron intensity data received from the first set of electron sensing elements, and

[0302] Generate a digital signal representing the sum;

[0303] The intensity value of the beam spot is determined based on the digital signal.

[0304] 62. The method according to any one of clauses 48 to 61, wherein generating an image of the wafer based on the intensity value comprises:

[0305] Obtain the intensity values ​​of multiple beam spots;

[0306] Obtain the trajectories of the multiple beam spots;

[0307] Mapping the trajectory to multiple scan locations on or within the wafer; and

[0308] The image of the wafer is constructed based on the intensity value and the scanning position.

[0309] 63. The method according to Clause 62, wherein the method further comprises:

[0310] Receive signals representing electron intensity data scanned from one or more electronic sensing elements;

[0311] Amplify the received signal;

[0312] Generate a digital signal representing the amplified signal; and

[0313] The image of the beam spot is generated based on the digital signal.

[0314] 64. The method according to any one of claims 45 to 63 further comprises: preprocessing the electron intensity data received from each of the plurality of electronic sensing elements using a set of signal conditioning circuits;

[0315] The set of intensity gradients mentioned above is determined based on preprocessed electron intensity data; and

[0316] The intensity value of the beam spot is determined based on preprocessed electron intensity data.

[0317] 65. A non-transitory computer-readable storage medium storing instructions, said instructions being executable by a computing device including one or more processors to cause said computing device to perform a method, said method comprising:

[0318] Acquire a set of intensity signals from multiple electronic sensing elements; and

[0319] At least one boundary of the beam spot is determined based on the set of intensity signals.

[0320] 66. The medium according to Clause 65, wherein the method further comprises:

[0321] The first group of electronic sensing elements among the plurality of electronic sensing elements is determined within the beam spot based on the at least one boundary.

[0322] 67. The medium according to Clause 66, wherein the method further comprises:

[0323] The intensity value of the beam spot is determined based on the electron intensity data received from the first set of electronic sensing elements.

[0324] 68. The medium according to Clause 67, wherein the method further comprises:

[0325] An image of the wafer is generated based on the intensity value.

[0326] 69. The medium according to any one of clauses 65 to 68, wherein the method further comprises:

[0327] A set of comparison decisions is generated by a set of signal level difference determination devices based on the comparison of electron intensity data from a pair of adjacent electron sensing elements among the plurality of electron sensing elements, wherein the set of intensity gradients is determined based on the generated set of comparison decisions.

[0328] 70. The medium according to Clause 69, wherein the signal level difference determining device includes a voltage comparator.

[0329] 71. The medium according to clause 69 or 70, wherein the plurality of electronic sensing elements form a sensor surface; wherein defining at least one boundary of the beam spot comprises:

[0330] The set of comparison decisions is associated with a set of locations on the sensor surface;

[0331] The first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and

[0332] The first position is determined to be part of the at least one boundary.

[0333] 72. The medium according to Clause 71, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the beam spot processing module is configured to determine the first position as a position between the first region and the second region.

[0334] 73. The medium according to any one of clauses 67 to 72, wherein determining the intensity value of the beam spot comprises:

[0335] Based on the at least one boundary, a second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot;

[0336] The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; and

[0337] The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component.

[0338] The image of the wafer is generated based on the compensation intensity value.

[0339] 74. The medium according to Clause 73, wherein determining the intensity value of the beam spot includes:

[0340] Selecting one or more electronic sensing elements from the second set of electronic sensing elements based on the distance between the one or more electronic sensing elements and the at least one boundary; and

[0341] The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

[0342] 75. A non-transitory computer-readable storage medium storing instructions, said instructions being executable by a computing device including one or more processors to cause said computing device to perform a method, said method comprising:

[0343] A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements;

[0344] The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients.

[0345] Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot;

[0346] Based on the second boundary, the second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot; and

[0347] The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

[0348] 76. The medium according to Clause 75, wherein determining the intensity value of one or both of the first beam spot and the second beam spot comprises:

[0349] Determine the third group of electronic sensing elements among the plurality of electronic sensing elements within the overlapping region; and

[0350] A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

[0351] 77. The medium according to clause 75 or 76, wherein the method further comprises:

[0352] Based on the overlapping region, the updated first boundary and the updated second boundary are determined; and

[0353] The first intensity value of the first beam spot and the second intensity value of the second beam spot are determined based on the updated first boundary and the updated second boundary, respectively.

[0354] 78. The medium according to Clause 77, wherein determining the updated first boundary and the updated second boundary based on the overlapping region comprises:

[0355] Determine the third boundary surrounding the center of the first beam spot;

[0356] Determine the first distance between the third boundary and the first boundary;

[0357] Determine the second distance between the third boundary and the second boundary;

[0358] A scaling factor is determined based on the first distance and the second distance; and

[0359] The first boundary and the second boundary of the update are determined based on the scaling factor.

[0360] 79. The medium as described in Clause 78, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

[0361] 80. The medium according to any one of clauses 67 to 79, wherein determining the intensity value of the beam spot comprises:

[0362] Based on the electron intensity data received from the one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; and

[0363] The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

[0364] 81. The medium according to any one of clauses 67 to 80, wherein the method further comprises:

[0365] Generate the sum of the electron intensity data received from the first set of electron sensing elements, and

[0366] Generate a digital signal representing the sum;

[0367] The intensity value of the beam spot is determined based on the digital signal.

[0368] 82. The medium according to any one of clauses 68 to 81, wherein generating an image of the wafer based on the intensity value comprises:

[0369] Obtain the intensity values ​​of multiple beam spots;

[0370] Obtain the trajectories of the multiple beam spots;

[0371] Mapping the trajectory to multiple scan locations on or within the wafer; and

[0372] The image of the wafer is constructed based on the intensity value and the scanning position.

[0373] 83. The medium according to Clause 82, wherein the method further comprises:

[0374] Receive signals representing electron intensity data scanned from one or more electronic sensing elements;

[0375] Amplify the received signal;

[0376] Generate a digital signal representing the amplified signal; and

[0377] The image of the beam spot is generated based on the digital signal.

[0378] 84. The medium according to any one of claims 65 to 83, wherein the method further comprises: preprocessing the electron intensity data received from each of the plurality of electronic sensing elements using a set of signal conditioning circuitry;

[0379] The set of intensity gradients mentioned above is determined based on preprocessed electron intensity data; and

[0380] The intensity value of the beam spot is determined based on preprocessed electron intensity data.

[0381] 85. A detector for receiving multiple beams of charged particles, comprising:

[0382] A receiving surface having multiple sensing elements, the receiving surface being configured to generate a set of intensity signals based on sensing multiple beams of charged particles; and

[0383] A processing system configured to determine at least one boundary of a beam spot based on the set of intensity signals and to determine a first set of sensing elements within the beam spot of the plurality of sensing elements.

[0384] It should be understood that the present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and changes can be made without departing from its scope. It is intended that the scope of the invention be limited only by the appended claims.

Claims

1. An electronic detection system, comprising: Multiple electronic sensing elements are configured to receive at least one electron beam, including backscattered electrons or secondary electrons, from a wafer; as well as Processing system, the processing system comprising: An intensity gradient determination circuit is configured to determine a set of intensity gradients based on electron intensity data received from each of the plurality of electronic sensing elements. Beam spot boundary determination module, wherein the beam spot boundary determination module is configured to: Based on the set of intensity gradients, at least one boundary of the beam spot of one of the at least one electron beams is determined, and Based on the at least one boundary, a first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the beam spot; and A beam spot intensity determination module, configured to determine the intensity value of the beam spot based on the electron intensity data received from the first set of electronic sensing elements; and An image reconstruction module is configured to generate an image of the wafer based on the intensity value.

2. The electron detection system of claim 1, wherein the intensity gradient determination circuit includes a set of comparators configured to compare electron intensity data received from a pair of adjacent electron sensing elements among the plurality of electron sensing elements; The set of intensity gradients is determined based on a set of comparison decisions made by the set of comparators.

3. The electronic detection system of claim 2, wherein the plurality of electronic sensing elements form a sensor surface; wherein the determination of at least one boundary of the beam spot includes the beam spot boundary determination module being configured to: The set of comparison decisions is associated with a set of locations on the sensor surface; The first position in the set of positions is determined based on a predetermined pattern of the set of comparative decisions; as well as The first position is determined to be part of the at least one boundary.

4. The electronic detection system of claim 3, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the beam spot boundary determination module is configured to determine the first position as a position between the first region and the second region.

5. The electronic detection system according to claim 1, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to: The second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot based on the at least one boundary; The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; as well as The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component. The image reconstruction module is configured to generate the image of the wafer based on the compensation intensity value.

6. The electronic detection system of claim 5, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to: Selecting one or more electronic sensing elements from the second group of electronic sensing elements based on the distance between one or more electronic sensing elements and the at least one boundary; and The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

7. The electronic detection system according to any one of claims 1 to 6, wherein the determination of at least one boundary of the beam spot includes the beam spot boundary determination module being configured to: The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients. The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

8. The electronic detection system of claim 7, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to: Determine the third group of electronic sensing elements among the plurality of electronic sensing elements within the overlapping region; and A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

9. The electronic detection system of claim 8, wherein the beam spot boundary determination module is further configured to determine an updated first boundary and an updated second boundary based on the overlapping region. The beam spot intensity determination module is configured to determine a first intensity value of the first beam spot and a second intensity value of the second beam spot based on the updated first boundary and the updated second boundary, respectively.

10. The electronic detection system of claim 9, wherein determining the updated first boundary and the updated second boundary based on the overlapping region includes the beam spot boundary determination module further configured to: Determine the third boundary surrounding the center of the first beam spot; Determine the first distance between the third boundary and the first boundary; Determine the second distance between the third boundary and the second boundary; The scaling factor is determined based on the first distance and the second distance; as well as The first boundary and the second boundary of the update are determined based on the scaling factor.

11. The electronic detection system according to claim 10, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

12. The electronic detection system of claim 1, wherein the determination of the intensity value of the beam spot includes the beam spot intensity determination module being further configured to: Based on electron intensity data received from one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; and The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

13. The electronic detection system according to claim 1, further comprising an electron intensity determination circuit, the electron intensity determination circuit being configured to: Generate the sum of the electron intensity data received from the first set of electron sensing elements, and Generate a digital signal representing the sum; The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on the digital signal.

14. The electronic detection system according to claim 13, wherein the electron intensity determination circuit comprises: A summing amplifier is configured to output a summing signal representing the sum based on electron intensity data selected by a signal switching matrix, wherein the signal switching matrix is ​​configured to select the electron intensity data of the first set of electron sensing elements based on the at least one boundary. Post-signal conditioning circuit, including: A variable gain amplifier is configured to amplify the summing signal from the summing amplifier; and An offset voltage generation circuit is configured to add an offset voltage to the amplified signal from the variable gain amplifier; and An analog-to-digital converter is configured to generate the digital signal based on the signal from the post-signal conditioning circuit.

15. The electronic inspection system of claim 5, wherein generating an image of the wafer based on the intensity value includes the image reconstruction module being configured to: The intensity values ​​of multiple beam spots are obtained from the beam spot intensity determination module; The trajectories of the plurality of beam spots are obtained from the beam spot boundary determination module; Mapping the trajectory to multiple scan locations on or within the wafer; and The image of the wafer is constructed based on the intensity value and the scanning position.

16. The electronic detection system of claim 1, wherein the processing system further comprises a beamspot imaging circuit, the beamspot imaging circuit being configured to: Receive signals representing electron intensity data from one or more electronic sensing elements scanned by a signal switching matrix; Generate an amplified digital signal representing the signal; and The digital signal is provided to a beamspot imaging module, wherein the beamspot imaging module is configured to generate an image of the beamspot.

17. The electronic detection system of claim 1, further comprising a set of signal conditioning circuits configured to preprocess the electron intensity data received from each of the plurality of electronic sensing elements; The intensity gradient determination circuit is configured to determine the set of intensity gradients based on preprocessed electron intensity data; as well as The beam spot intensity determination module is configured to determine the intensity value of the beam spot based on preprocessed electron intensity data.

18. A method comprising: A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements; as well as At least one boundary of the beam spot is determined based on the set of intensity gradients.

19. The method of claim 18, further comprising: Based on the at least one boundary, a first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the beam spot.

20. The method of claim 19, further comprising: The intensity value of the beam spot is determined based on the electron intensity data received from the first set of electronic sensing elements.

21. The method of claim 20, further comprising: An image of the wafer is generated based on the intensity value.

22. The method according to any one of claims 18 to 21, further comprising: A set of comparison decisions is generated by a set of signal level difference determination devices based on comparisons of electron intensity data from adjacent electron sensing elements among the plurality of electron sensing elements, wherein the set of intensity gradients is determined based on the generated set of comparison decisions.

23. The method of claim 22, wherein the signal level difference determining device comprises a voltage comparator.

24. The method of claim 23, wherein the plurality of electronic sensing elements form a sensor surface; Determining at least one boundary of the beam spot includes: The set of comparison decisions is associated with a set of locations on the sensor surface; The first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and The first position is determined to be part of the at least one boundary.

25. The method of claim 24, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein the first position is determined as a position between the first region and the second region.

26. The method of any one of claims 21, wherein determining the intensity value of the beam spot further comprises: Based on the at least one boundary, a second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot; The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; as well as The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component. The image of the wafer is generated based on the compensation intensity value.

27. The method of claim 26, wherein determining the intensity value of the beam spot comprises: The one or more electronic sensing elements are selected from the second group of electronic sensing elements based on the distance between one or more electronic sensing elements and the at least one boundary; as well as The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

28. A method comprising: A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements; The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients. Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot; The second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot based on the second boundary. as well as The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

29. The method of claim 28, further comprising determining an intensity value of at least one of the first and second beam spots, wherein determining the intensity value further comprises: A third group of electronic sensing elements is identified within the overlapping region; as well as A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

30. The method of claim 28 or 29, further comprising: The updated first boundary and the updated second boundary are determined based on the overlapping region; as well as The first intensity value of the first beam spot and the second intensity value of the second beam spot are determined based on the updated first boundary and the updated second boundary, respectively.

31. The method of claim 30, wherein determining the updated first boundary and the updated second boundary based on the overlapping region comprises: Determine the third boundary surrounding the center of the first beam spot; Determine the first distance between the third boundary and the first boundary; Determine the second distance between the third boundary and the second boundary; The scaling factor is determined based on the first distance and the second distance; as well as The first boundary and the second boundary of the update are determined based on the scaling factor.

32. The method of claim 31, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

33. The method according to any one of claims 20 or 29, wherein determining the intensity value of the beam spot comprises: The fault of the one or more electronic sensing elements is determined based on the electron intensity data received from one or more electronic sensing elements in the first group of electronic sensing elements; as well as The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

34. The method of claim 20 or 29, further comprising: Generate the sum of the electron intensity data received from the first set of electron sensing elements, and Generate a digital signal representing the sum; The intensity value of the beam spot is determined based on the digital signal.

35. The method of claim 20 or 29, wherein generating an image of the wafer based on the intensity value comprises: Obtain the intensity values ​​of multiple beam spots; Obtain the trajectories of the multiple beam spots; Map the trajectory to multiple scan locations on or within the wafer; as well as The image of the wafer is constructed based on the intensity value and the scanning position.

36. The method according to claim 35, wherein, The method further includes: Receive signals representing electron intensity data scanned from one or more electronic sensing elements; Amplify the received signal; Generate a digital signal representing the amplified signal; and The image of the beam spot is generated based on the digital signal.

37. The method of claim 20 or 29, further comprising: A set of signal conditioning circuits is used to preprocess the electron intensity data received from each of the plurality of electronic sensing elements; The set of intensity gradients mentioned above was determined based on preprocessed electron intensity data; as well as The intensity value of the beam spot is determined based on preprocessed electron intensity data.

38. A non-transitory computer-readable storage medium storing instructions, said instructions being executable by a computing device including one or more processors to cause said computing device to perform a method, said method comprising: A set of intensity signals is acquired from multiple electronic sensing elements; as well as At least one boundary of the beam spot is determined based on the set of intensity signals.

39. The medium according to claim 38, wherein the method further comprises: The first group of electronic sensing elements among the plurality of electronic sensing elements is determined within the beam spot based on the at least one boundary.

40. The medium of claim 39, wherein the method further comprises: The intensity value of the beam spot is determined based on the electron intensity data received from the first set of electronic sensing elements.

41. The medium of claim 40, wherein the method further comprises: An image of the wafer is generated based on the intensity value.

42. The medium of claim 40, wherein the method further comprises: A set of comparison decisions is generated by a set of signal level difference determination devices based on the comparison of electron intensity data from a pair of adjacent electron sensing elements among the plurality of electron sensing elements, wherein the set of intensity gradients is determined based on the generated set of comparison decisions.

43. The medium according to claim 42, wherein, The signal level difference determination device includes a voltage comparator.

44. The medium of claim 43, wherein the plurality of electronic sensing elements form a sensor surface; wherein, Determining at least one boundary of the beam spot includes: The set of comparison decisions is associated with a set of locations on the sensor surface; The first position in the set of positions is determined based on a predetermined pattern of the set of comparison decisions; and The first position is determined to be part of the at least one boundary.

45. The medium of claim 44, wherein the predetermined pattern includes a first set of identical comparison decisions in a first region on the sensor surface and a second set of switching comparison decisions in a second region on the sensor surface, wherein, The speckle processing module is configured to determine the first position as the location between the first region and the second region.

46. ​​The medium according to claim 41, wherein, Determining the intensity value of the beam spot includes: Based on the at least one boundary, a second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be outside the beam spot; The noise component is determined based on the electron intensity data received from the second set of electronic sensing elements; and The compensation intensity value is determined based on a combination of the intensity value determined from the electron intensity data of the first set of electronic sensing elements and the noise component. The image of the wafer is generated based on the compensation intensity value.

47. The medium of claim 46, wherein determining the intensity value of the beam spot comprises: The one or more electronic sensing elements are selected from the second group of electronic sensing elements based on the distance between one or more electronic sensing elements and the at least one boundary; as well as The noise component is determined based on the electron intensity data received from one or more selected electronic sensing elements.

48. A non-transitory computer-readable storage medium storing instructions, said instructions being executable by a computing device including one or more processors to cause said computing device to perform a method, said method comprising: A set of intensity gradients is determined based on electron intensity data received from each of a plurality of electron sensing elements; The first boundary of the first beam spot and the second boundary of the second beam spot are determined based on the set of intensity gradients. Based on the first boundary, the first group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the first beam spot; The second group of electronic sensing elements among the plurality of electronic sensing elements is determined to be within the second beam spot based on the second boundary. as well as The overlap region between the first beam spot and the second beam spot is determined based on the first boundary and the second boundary.

49. The medium of claim 48, wherein determining the intensity value of one or both of the first beam spot and the second beam spot comprises: A third group of electronic sensing elements is identified within the overlapping region; as well as A first intensity value for the first beam spot and a second intensity value for the second beam spot are determined, wherein the electron intensity data received from the third set of electronic sensing elements is excluded.

50. The medium according to claim 48 or 49, wherein the method further comprises: The updated first boundary and the updated second boundary are determined based on the overlapping region; as well as The first intensity value of the first beam spot and the second intensity value of the second beam spot are determined based on the updated first boundary and the updated second boundary, respectively.

51. The medium of claim 50, wherein determining the updated first boundary and the updated second boundary based on the overlapping region comprises: Determine the third boundary surrounding the center of the first beam spot; Determine the first distance between the third boundary and the first boundary; Determine the second distance between the third boundary and the second boundary; The scaling factor is determined based on the first distance and the second distance; as well as The first boundary and the second boundary of the update are determined based on the scaling factor.

52. The medium according to claim 51, wherein the scaling factor is also determined based on a predetermined signal-to-noise ratio threshold.

53. The medium according to claim 40 or 49, wherein determining the intensity value of the beam spot comprises: Based on the electron intensity data received from one or more electronic sensing elements, it is determined that one or more electronic sensing elements in the first group of electronic sensing elements have malfunctioned; as well as The intensity value of the beam spot is determined, wherein the electronic intensity data received from the one or more electronic sensing elements is excluded.

54. The medium according to claim 40 or 49, wherein the method further comprises: Generate the sum of the electron intensity data received from the first set of electron sensing elements, and Generate a digital signal representing the sum; The intensity value of the beam spot is determined based on the digital signal.

55. The medium according to claim 41 or 49, wherein generating an image of the wafer based on the intensity value comprises: Obtain the intensity values ​​of multiple beam spots; Obtain the trajectories of the multiple beam spots; Map the trajectory to multiple scan locations on or within the wafer; as well as The image of the wafer is constructed based on the intensity value and the scanning position.

56. The medium according to claim 55, wherein the method further comprises: Receive signals representing electron intensity data scanned from one or more electronic sensing elements; Amplify the received signal; Generate a digital signal representing the amplified signal; as well as The image of the beam spot is generated based on the digital signal.

57. The medium according to claim 40 or 49, wherein the method further comprises: A set of signal conditioning circuits is used to preprocess the electron intensity data received from each of the plurality of electronic sensing elements; The set of intensity gradients mentioned above was determined based on preprocessed electron intensity data; as well as The intensity value of the beam spot is determined based on preprocessed electron intensity data.

58. A detector for receiving multiple beams of charged particles, comprising: A receiving surface having multiple sensing elements, the receiving surface being configured to generate a set of intensity signals based on sensing multiple beams of charged particles; as well as A processing system configured to determine at least one boundary of a beam spot based on the set of intensity signals and to determine a first set of sensing elements within the beam spot of the plurality of sensing elements.

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