Detecting dynamic switching of switch matrix

Abstract

A charged particle detector includes an array of sensing elements that are selectively grouped from one another by a switching matrix. The sensing elements may be grouped in a shape and position corresponding to an expected shape and position of the beam spot to be detected. In the detection process, the sensing element group can be updated in real time. The updating may include adding a peripheral sensing element to the group and removing the peripheral sensing element from the group. If it is determined that the sensing element receives sufficient radiation from the beam spot, the sensing element may be added. If it is determined that the sensing element receives insufficient radiation from the beam spot, the sensing element may be removed. The determination may be made by a threshold circuit located within each sensing element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22189246.6 filed on August 8, 2022, and the entire contents of which are incorporated herein by reference. Technical Field

[0003] The description herein relates to detectors, and more particularly, to detectors suitable for charged particle detection. Background Art

[0004] Detectors can be used to sense physically observable phenomena. For example, some charged particle beam tools (e.g., electron microscopes) include detectors that receive charged particles projected from a sample and output a detection signal. The detection signal can be used to reconstruct an image of the structure of the sample being inspected, and can be used, for example, to reveal defects in the sample. In the manufacture of semiconductor devices, it is increasingly important to detect defects in samples, which may include a large number of densely packed miniature integrated circuit (IC) components. Inspection systems can be provided for this purpose. For example, charged particle (e.g., electron) beam microscopes (e.g., scanning electron microscopes (SEMs) or transmission electron microscopes (TEMs)) are able to reduce resolution to less than 1 nanometer and can be used as practical tools for inspecting IC components with feature sizes less than 100 nanometers. The working principle of an electron microscope is to irradiate a sample with an electron beam and then detect secondary or backscattered electrons (or other types of secondary particles) on a detector. Secondary particles can form one or more beam spots on the detector surface.

[0005] Some detectors include a pixelated array of multiple sensing elements. The pixelated array is useful because it allows the detector configuration to be adapted to the size and shape of the beam spot formed on the detector. When multiple primary beams are used, multiple secondary beams are incident on the detector and the pixelated array can be divided into different areas of the detector associated with different beam spots. Each area can form its own group of sensing elements (pixels) for detecting a single beam spot.

[0006] To form detection groups of different beam spots, a typical process involves two steps. First, a picture of the detector surface is taken. In the so-called "picture mode", the output of each sensing element of the pixelated array can be read, and an image representing the projection pattern of the secondary beam spots on the detector surface can be formed. That is, an image of the entire detector surface is generated. Based on this image, the boundaries of each beam spot can be estimated, and a group of sensing elements can be selected so that the boundaries of the group are approximately the boundaries of the beam spots. This selected group of sensing elements can be used later to detect the beam spots during the "beam mode". Summary of the invention

[0007] Some embodiments of the present disclosure provide a charged particle detector, comprising: a substrate; a plurality of switch elements formed on the substrate and configured to form a switch matrix, the switch matrix having a plurality of inputs, each input configured to be connected to a different sensor element among a plurality of sensor elements, each sensor element configured to generate a signal in response to a charged particle hitting the sensor element, the switch matrix configured to combine a group of signals generated from a sensor element group, the sensor element group being associated with a charged particle beam spot formed on the charged particle detector; and a plurality of threshold circuits, each threshold circuit coupled to a different sensor element among the plurality of sensor elements, wherein a first threshold circuit among the plurality of threshold circuits is coupled to a first sensor element among the plurality of sensor elements and configured to actuate a first switch element of the switch matrix based on a comparison of a signal level of the first sensor element with a threshold. The first sensor element may be configured to be identified as a candidate to be added to or removed from the sensor element group based on the proximity of the first sensor element to a boundary of the sensor element group. The first threshold circuit may be configured to initiate the comparison in response to the first sensor element being identified as a candidate.

[0008] Some embodiments of the present disclosure provide a non-transitory computer-readable medium storing a set of instructions that can be executed by at least one processor of a device to cause the device to perform a method. The method may include: receiving electrons of a plurality of secondary electron beams emitted by a sample in response to a plurality of primary beams of a multi-beam SEM interacting with the sample through a sensing element of an electron detector, each of the secondary electron beams being associated with a different primary beam of the plurality of primary beams; coupling a first group of sensing elements of the electron detector corresponding to a first beam spot of one of the secondary electron beams based on the received electrons. The method may also include: coupling the first sensing element to the first group in response to a first detected charge at the first sensing element exceeding a first threshold; wherein coupling the first sensing element to the first group enables charge to be transferred from the first sensing element to a signal readout path of the first group. Alternatively or additionally, the method may also include decoupling the second sensing element from the first group in response to a second detected charge at the second sensing element dropping below a second threshold, wherein decoupling the second sensing element from the first group prevents charge from being transferred from the second sensing element to a signal readout path of the first group. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram illustrating an exemplary charged particle beam inspection system consistent with embodiments of the present disclosure.

[0010] Figure 2 is a schematic diagram showing an exemplary multi-beam tool consistent with an embodiment of the present disclosure, which may be Figure 1 A portion of an exemplary charged particle beam inspection system.

[0011] Figure 3A is a schematic diagram of an exemplary structure of a detector consistent with an embodiment of the present disclosure.

[0012] Figure 3B is a diagram illustrating an exemplary surface of a detector array consistent with embodiments of the present disclosure.

[0013] Figure 4 is a diagram illustrating an exemplary detector array with switching elements consistent with embodiments of the present disclosure.

[0014] Figure 5 is a diagram showing a cross-sectional view of a layer structure of a detector consistent with an embodiment of the present disclosure.

[0015] Figure 6 is a diagram showing a cross-sectional view of a sensing element of a detector consistent with an embodiment of the present disclosure.

[0016] Figure 7 is a diagram showing an exemplary partial arrangement of a detector consistent with an embodiment of the present disclosure.

[0017] Figure 8 is a diagram illustrating another exemplary partial arrangement of a detector consistent with an embodiment of the present disclosure.

[0018] Fig. 9 is a diagram illustrating a detection system consistent with an embodiment of the present disclosure.

[0019] Fig. 10A is a diagram showing beam spots and sensing element group boundaries consistent with an embodiment of the present disclosure.

[0020] Fig. 10B is a diagram illustrating multiple beam spots and multiple sensing element group boundaries consistent with an embodiment of the present disclosure.

[0021] Fig.11A - Figure B is a diagram showing a sensing element circuit architecture consistent with an embodiment of the present disclosure.

[0022] Fig. 11C is a diagram illustrating a sensing element circuit architecture consistent with an embodiment of the present disclosure.

[0023] FIG. 12A to FIG. 12F An exemplary process for updating a sensor element group consistent with an embodiment of the present disclosure is shown.

[0024] Fig.13 is a flow chart of an exemplary method for updating a sensor element group consistent with embodiments of the present disclosure. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to exemplary embodiments, examples of which are shown in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different figures represent the same or similar elements. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with aspects related to the subject matter described in the appended claims. For example, although some embodiments are described in the context of utilizing charged particle beams (e.g., electron beams), the present disclosure is not limited thereto. Other types of charged particle beams may be applied similarly. In addition, other imaging systems, such as optical imaging, photoelectric detection, x-ray detection, etc., may be used.

[0026] Electronic devices consist of circuits formed on a semiconductor material called a substrate. Semiconductor materials can include, for example, silicon, gallium arsenide, indium phosphide, or silicon germanium. Many circuits can be formed together on the same piece of silicon, called an integrated circuit, or IC. The size of these circuits has been greatly reduced, so more circuits can fit on a substrate. For example, the IC chip in a smartphone can be as small as a thumbnail, but may contain more than 2 billion transistors, each less than one thousandth the size of a human hair.

[0027] Manufacturing these ICs, which have extremely small structures or components, is a complex, time-consuming, and expensive process that typically involves hundreds of individual steps. An error in even one step can cause a defect in the finished IC, rendering it unusable. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process; that is, to increase the yield of the overall process.

[0028] An integral part of improving yield is monitoring the chip manufacturing process to ensure that a sufficient number of functional integrated circuits are produced. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection can be performed using a scanning charged particle microscope ("SCPM"). For example, the SCPM can be a scanning electron microscope (SEM). The SCPM can be used to image these extremely small structures, in effect taking a "picture" of the wafer structure. This image can be used to determine if the structure is formed correctly in the correct location. If the structure is defective, the process can be adjusted to reduce the likelihood that the defect will occur again.

[0029] The working principle of the SEM is similar to that of a camera. A camera takes pictures by receiving and recording the intensity of light reflected or emitted from a person or object. The SEM takes pictures by receiving and recording the energy or number of electrons reflected or emitted from a wafer structure. Before taking such a "picture", an electron beam can be projected onto the structure, and when the electrons are reflected or emitted ("leave") from the structure (e.g., from the wafer surface, from the structure below the wafer surface, or both), the detector of the SEM can receive and record the energy or number of these electrons to generate an inspection image. To take such a "picture", the electron beam can scan the wafer (e.g., in a row-by-row or zigzag manner), and the detector can receive the leaving electrons from the area under the projection of the electron beam (called a "beam spot"). The detector can receive and record the leaving electrons from each beam spot at a time, and merge the information recorded for all beam spots to generate an inspection image. Some SEMs use a single electron beam (called "single-beam SEM") to take a single "picture" to generate a detection image, while some SEMs use multiple electron beams (called "multi-beam SEM") to take multiple "sub-pictures" of the wafer in parallel and stitch them together to generate a detection image. By using multiple electron beams, the SEM can provide more electron beams to the structure to obtain these multiple "sub-pictures", resulting in more electrons being ejected from the structure. Therefore, the detector can receive more ejected electrons at the same time and generate a detection image of the wafer structure with higher efficiency and faster speed.

[0030] The emitted electrons received by the detector of the SEM may cause the detector to generate an electrical signal (e.g., a current signal or a voltage signal) that is comparable to the energy of the emitted electrons and the intensity of the electron beam. For example, the amplitude of the electrical signal may be comparable to the charge of the received emitted electrons. The detector may output the electrical signal to an image processor, which may process the electrical signal to form an image of the wafer structure. A multi-beam SEM system uses multiple electron beams for inspection, and the detector of the multi-beam SEM system may have multiple sections to receive them. Each section may have multiple sensing elements and may be used to form a "picture" of a sub-area of ​​the wafer. The "pictures" generated based on the signals from each section of the detector may be combined to form a complete picture of the inspected wafer.

[0031] The various parts of the detector can be connected to each other for communication, and each part of the detector can have a corresponding signal processing circuit for processing the electrical signal generated by the detector. When the electron beam hits a part, the signal processing circuit of the part can be activated for signal processing. When the electron beam hits multiple adjacent parts, their signal processing circuits can be activated in a coordinated manner for signal processing. When no electron beam hits the part, the signal processing circuit of the part can be deactivated or made idle. When the electron beam hits a faulty part, the signal processing circuit of its adjacent part can be activated for signal processing. With this interconnected part design, the detector of the SEM can provide flexibility and fault tolerance for the signal processing of the detector.

[0032] In addition to activating the sensing elements at the partial level, the individual sensing elements can be coupled to each other using an array of switching elements in the detector switch matrix. By coupling the individual sensing elements, the detector can functionally group multiple sensing elements together so that the group of sensing elements matches the shape and position of the beam spot on the detector. This can be achieved by first operating in picture mode to determine the appropriate group of sensing elements, and then coupling the selected sensing elements together for normal use in beam mode.

[0033] In picture mode, the output of each sensor element in the detector array can be read and an image (e.g., a secondary electron beam spot image) representing the projection pattern of the secondary beam spot on the detector surface is formed. That is, an image of the entire detector surface is generated. Based on the image, the boundaries of each beam spot can be estimated, and a sensor element group can be selected so that the boundaries of the group are approximately the boundaries of the beam spot. The selected sensor element group can be used later to detect the beam spot during beam mode.

[0034] In beam mode, for example during inspection, the sensing elements located within a defined boundary can be grouped together and their outputs can be combined to obtain the intensity of one secondary beam spot associated with the boundary. Sensing elements outside the boundary can be deactivated to reduce parasitic parameters or unwanted electromagnetic effects from circuit elements. Thus, picture mode can be used to determine the boundary of the desired group of sensing elements that can be used during inspection in beam mode. The boundary ideally includes every sensing element that receives a portion of the beam spot and excludes every sensing element that does not receive the beam spot. Crosstalk occurs when electrons from different beam spots land in the same group of sensing elements and should be avoided.

[0035] There are many performance indicators for detectors, one of which is the "pixel rate", which is the rate at which image pixels are generated. The pixel rate can represent the processing bandwidth of digital data in a digital system, and the maximum pixel rate of a detector can represent the maximum digital data processing speed of the detector. Another indicator is the "analog signal bandwidth", which is the frequency range between the lowest and highest frequencies that the analog signal can reach. High-frequency analog signals can reflect the "details" of the detected structure. The analog signal bandwidth represents the detection capability of the detector and the fineness of the detection results, which is a performance indicator different from the pixel rate. For example, even if the pixel rate is high, if the analog signal bandwidth is low, the detected image may still be blurred, because the low analog signal bandwidth may lose some details of the structure, and these details may not be reflected in the detected image.

[0036] Pixel rate and analog signal bandwidth are susceptible to parasitic parameters. Parasitic parameters may include parasitic capacitance (e.g., stray capacitance), parasitic resistance, or parasitic inductance. Parasitic parameters are generated even when certain components are not working. Parasitic parameters may change the design specifications of the components and may adversely affect the performance of the detector, such as suppressing signal dynamics and reducing pixel rate. For example, stray capacitance may prevent the movement of charge. Parasitic resistance may increase internal detection signal loss. Parasitic inductance may prevent the flow of dynamic current. In addition, parasitic parameters may introduce noise and interference to the inspection image. Further discussion of parasitic parameters related to detector architecture can be found in International Publication No. WO 2021 / 239754A1, the contents of which are incorporated herein by reference in their entirety.

[0037] The pixel rate and analog signal bandwidth can have a significant impact on other performance indicators of the detector, such as the signal-to-noise ratio ("SNR") or performance capacity (e.g., maximum inspection speed or maximum inspection throughput) of the detector. To increase the pixel rate and analog signal bandwidth, the detector can be designed to shorten the electrical connection distance between each sensing element and its signal processing circuit, which can suppress the generation of parasitic parameters (e.g., series resistance, parasitic capacitance, or series inductance). Alternatively, the architecture of the signal processing circuit can be enhanced or redesigned to make the detector less sensitive to parasitic parameters.

[0038] It is desirable to match the sensor element group to the beam spot as closely as possible. If a sensor element outside the selected group receives a portion of the beam spot, that portion will not be detected. However, each sensor element added to the group introduces unnecessary parasitic parameters. Furthermore, increasing the size of the sensor element group increases the risk of crosstalk from adjacent beam spots. Therefore, the sensor element group cannot simply be defined to be much larger than the beam spot, otherwise a penalty will be incurred.

[0039] One problem that causes the beam spot to not match the group of sensing elements assigned to it is that the beam spot drifts over time. The size, shape or position of the beam spot may change during the charged particle beam process so that the original group boundaries no longer match the existing beam spot. Sensing elements that are not part of the group may be receiving a portion of the beam spot and not passing any signal to the signal readout path of the detector. Additionally, sensing elements in a group may not receive any portion of the beam spot. These sensing elements add parasitic parameters to the system without contributing any useful information.

[0040] In order to dynamically update the group, it would be helpful to know which sensor elements are receiving the beam spot and which are not. However, this can present some challenges. One challenge can be the lack of uniquely identifiable intensity readings from individual sensor elements during beam mode operation. This is because, during beam mode, the sensor elements may be grouped together in the signal readout path, rendering their signals indistinguishable, or completely separated from the signal readout path, potentially making them unreadable by the detector. Therefore, in traditional sensing architectures, it can be difficult to determine which sensor elements should be added to or removed from the group.

[0041] In the present disclosure, a detector with an improved structure is provided for dynamically updating a group of sensing elements during use (e.g., in beam mode). The detector may include a plurality of sensing elements, each sensing element having a threshold circuit configured to indicate whether a substantial portion of a beam spot is incident on the sensing element. When activated, the threshold circuit may be configured to divert at least a portion of any signal (e.g., current) generated at the sensing element and compare the signal to a predetermined threshold. The threshold may be a first high threshold (for adding a sensing element to a group) or a second low threshold (for removing a sensing element from a group). Based on the comparison, a sensing element may be added to or removed from the group. A sensing element may be added to a group by closing a switch element in a switch matrix (thereby forming a connection), or may be removed from a group by opening a switch element in a switch matrix (thereby disconnecting a connection).

[0042] When a sensing element is determined to be a candidate for updating, a threshold circuit in the sensing element may be activated. A sensing element may be considered a candidate based on its proximity to a boundary of a sensing element group. For example, a sensing element within or outside a group may be a candidate when it is in close proximity to a grouping boundary. A controller may send a control signal to activate a threshold operation of the threshold circuit. For example, the controller may be a local control circuit, such as a circuit within a detector. In some embodiments, the controller may be remote from the detector or remote from a substrate on which the sensing element is located. The control signal may determine the threshold to be applied, and the switch element to be actuated when the threshold is met.

[0043] The process of identifying candidates and updating the sensor array can be repeated over and over again during the charged particle beam process so that the sensor array can quickly and accurately track any changes in the size, shape, position or other properties of the beam spot on the detector.

[0044] The objects and advantages of the present invention can be achieved by the elements and combinations thereof described in the embodiments described herein. However, the embodiments of the present invention are not necessarily required to achieve these exemplary objects or advantages, and some embodiments may not achieve any of the objects or advantages.

[0045] Without limiting the scope of the present disclosure, some embodiments may be described in the context of providing detection systems and detection methods in systems utilizing electron beams ("e-beams"). However, the present disclosure is not limited thereto. Other types of charged particle beams may be similarly applied. In addition, the detection systems and methods may be used in other imaging systems, such as optical imaging, photon detection, x-ray detection, ion detection, and the like.

[0046] As used herein, unless expressly stated otherwise, the term "or" encompasses all possible combinations unless not feasible. For example, if a component is specified to include A or B, then unless expressly stated otherwise or not feasible, the component may include A, or B, or A and B. As a second example, if a component is specified to include A, B, or C, then unless expressly stated otherwise or not feasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0047] For the sake of clarity, the relative sizes of the components in the figures may be exaggerated. In the following description of the figures, the same or similar reference numerals denote the same or similar components or entities, and only the differences with respect to the various embodiments are described.

[0048] Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure is shown. The EBI system 100 may be used for imaging. Figure 1 As shown, the EBI system 100 includes a main chamber 101, a load / lock chamber 102, a beam tool 104, and an equipment front end module (EFEM) 106. The beam tool 104 is located in the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include (a plurality of) additional loading ports. The first loading port 106a and the second loading port 106b receive a wafer front opening transport box (FOUP) containing a wafer (e.g., a semiconductor wafer or a wafer made of other materials) or a sample to be inspected (wafers and samples can be used interchangeably). "Batch" refers to a plurality of wafers that can be loaded as a batch for processing.

[0049] One or more robots (not shown) in the EFEM 106 can transfer the wafer to the load / lock chamber 102. The load / lock chamber 102 is connected to a load / lock vacuum pump system (not shown), which removes gas molecules in the load / lock chamber 102 to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robots (not shown) can transfer the wafer from the load / lock chamber 102 to the main chamber 101. The main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules in the main chamber 101 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer will be inspected by the beam tool 104. The beam tool 104 can be a single beam system or a multi-beam system.

[0050] The controller 109 is electronically connected to the beam tool 104. The controller 109 may be a computer configured to perform various controls of the EBI system 100. Figure 1 The controller 109 is shown in FIG. 1 as being external to the structure including the main chamber 101 , the load / lock chamber 102 , and the EFEM 106 , but it will be appreciated that the controller 109 may be part of the structure.

[0051] In some embodiments, the controller 109 may include one or more processors (not shown). The processor may be a general or special electronic device capable of manipulating or processing information. For example, the processor may include any number of any combination of the following: a central processing unit (or "CPU"), a graphics processing unit (or "GPU"), an optical processor, a programmable logic controller, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a programmable logic array (PLA), a programmable array logic (PAL), a general array logic (GAL), a complex programmable logic device (CPLD), a field programmable gate array (FPGA), a system on a chip (SoC), an application-specific integrated circuit (ASIC), and any type of circuit capable of data processing. The processor may also be a virtual processor, which includes one or more processors distributed on multiple machines or devices coupled via a network.

[0052] In some embodiments, the controller 109 may also include one or more memories (not shown). The memory may be a general or specific electronic device capable of storing processor-accessible code and data (e.g., via a bus). For example, the memory may include any number of any combination of the following: random access memory (RAM), read-only memory (ROM), optical disk, magnetic disk, hard disk, solid-state drive, flash drive, secure digital (SD) card, memory stick, compact flash (CF) card, or any type of storage device. The code and data may include an operating system (OS) and one or more applications (or "apps") for specific tasks. The memory may also be a virtual memory, which includes one or more memories distributed on multiple machines or devices coupled via a network.

[0053] Figure 2 An exemplary multi-beam tool 104 (also referred to herein as apparatus 104) and an ...) consistent with embodiments of the present disclosure and configurable for use with an EBI system 100 ( Figure 1 ) is a schematic diagram of an image processing system 290.

[0054] The beam tool 104 includes a charged particle source 202, a gun aperture 204, a converging lens 206, a primary charged particle beam 210 emitted from the charged particle source 202, a source conversion unit 212, a plurality of sub-beams 214, 216, and 218 of the primary charged particle beam 210, a primary projection optical system 220, a motorized wafer stage 280, a wafer holder 282, a plurality of secondary charged particle beams 236, 238, and 240, a secondary optical system 242, and a charged particle 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 charged particle detection device 244 may include detection sub-areas 246, 248, and 250.

[0055] Charged particle source 202, gun aperture 204, focusing lens 206, source conversion unit 212, beam splitter 222, deflection scanning unit 226, and objective lens 228 may be aligned with a primary optical axis 260 of apparatus 104. Secondary optical system 242 and charged particle detection device 244 may be aligned with a secondary optical axis 252 of apparatus 104.

[0056] The charged particle source 202 may emit one or more charged particles, such as electrons, protons, ions, muons, or any other particles carrying an electric charge. In some embodiments, the charged particle source 202 may be an electron source. For example, the charged particle 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 charged particle beam 210 (in this case, a primary electron beam) having an intersection (virtual or real) 208. For ease of explanation and without ambiguity, electrons are used as examples in some descriptions herein. However, it should be noted that any charged particles may be used in any embodiment of the present disclosure, not limited to electrons. The primary charged particle beam 210 may be considered to be emitted from the intersection 208. The gun aperture 204 may block the peripheral charged particles of the primary charged particle beam 210 to reduce the Coulomb effect. The Coulomb effect may cause the probe point size to increase.

[0057] The source conversion unit 212 may include an image forming element array and a beam limiting aperture array. The image forming element array may include a micro deflector or a micro lens array. The image forming element array may form multiple parallel images (virtual or real) of the intersection 208 with the multiple sub-beams 214, 216, and 218 of the primary charged particle beam 210. The beam limiting aperture array may limit the multiple sub-beams 214, 216, and 218. Although Figure 2 , three sub-beams 214, 216, and 218 are shown, but embodiments of the present disclosure are not limited thereto. For example, in some embodiments, the apparatus 104 may be configured to generate a first number of sub-beams. In some embodiments, the first number of sub-beams may be in the range of 1 to 1000. In some embodiments, the first number of sub-beams may be in the range of 200-500. In an exemplary embodiment, the apparatus 104 may generate 400 sub-beams.

[0058] The converging lens 206 can focus the primary charged particle beam 210. By adjusting the focusing ability of the converging lens 206 or changing the radial size of the corresponding beam limiting aperture in the beam limiting aperture array, the current of the sub-beams 214, 216 and 218 downstream of the source conversion unit 212 can be changed. The objective lens 228 can focus the sub-beams 214, 216 and 218 onto the wafer 230 for imaging, and can form a plurality of detection points 270, 272 and 274 on the surface of the wafer 230.

[0059] The beam splitter 222 can be a Wien filtering type beam splitter that generates an electrostatic dipole field and a magnetic dipole field. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on the charged particles (e.g., electrons) of the beams 214, 216, and 218 can be substantially equal in magnitude and opposite in direction to the force exerted by the magnetic dipole field on the charged particles. Therefore, the beams 214, 216, and 218 can pass straight through the beam splitter 222 at a zero deflection angle. However, the total dispersion of the beams 214, 216, and 218 generated by the beam splitter 222 can also be non-zero. The beam splitter 222 can separate the secondary charged particle beams 236, 238, and 240 from the sub-beams 214, 216, and 218, and direct the secondary charged particle beams 236, 238, and 240 to the secondary optical system 242.

[0060] The deflection scanning unit 226 can deflect the beamlets 214, 216, and 218 to scan the detection points 270, 272, and 274 on the surface area of ​​the wafer 230. In response to the incidence of the beamlets 214, 216, and 218 at the detection points 270, 272, and 274, secondary charged particle beams 236, 238, and 240 can be emitted from the wafer 230. The secondary charged particle beams 236, 238, and 240 may include charged particles (e.g., electrons) having an energy distribution. For example, the secondary charged particle beams 236, 238, and 240 may be secondary electron beams, including secondary electrons (energy ≤ 50 eV) and backscattered electrons (energy between 50 eV and the landing energy of the beamlets 214, 216, and 218). The secondary optical system 242 can focus the secondary charged particle beams 236, 238, and 240 onto detection sub-regions 246, 248, and 250 of the charged particle detection device 244. The detection sub-regions 246, 248, and 250 can be configured to detect the corresponding secondary charged particle beams 236, 238, and 240 and generate corresponding signals (e.g., voltage, current, etc.) for reconstructing the SCPM image of the structure on or below the surface area of ​​the wafer 230.

[0061] The generated signals may represent the intensities of the secondary charged particle beams 236, 238, and 240, and may be provided to an image processing system 290 in communication with the charged particle detection device 244, the primary projection optical system 220, and the motorized wafer stage 280. The movement speed of the motorized wafer stage 280 may be synchronized and coordinated with the beam deflection controlled by the deflection scanning unit 226, so that the movement of the scanning detection points (e.g., scanning detection points 270, 272, and 274) may orderly cover the region of interest on the wafer 230. The parameters of such synchronization and coordination may be adjusted to accommodate different materials of the wafer 230. For example, different materials of the wafer 230 may have different resistance-capacitance characteristics, which may result in different signal sensitivities to the movement of the scanning detection points.

[0062] The intensity of the secondary charged particle beams 236, 238, and 240 may vary depending on the external or internal structure of the wafer 230, and thus may indicate whether the wafer 230 contains defects. In addition, as described above, the sub-beams 214, 216, and 218 may be projected to different locations on the top surface of the wafer 230 or different sides of the local structure of the wafer 230 to generate secondary charged particle beams 236, 238, and 240 that may have different intensities. Therefore, by mapping the intensities of the secondary charged particle beams 236, 238, and 240 to the regions of the wafer 230, the image processing system 290 may reconstruct an image reflecting the internal or external structural features of the wafer 230.

[0063] In some embodiments, the image processing system 290 may include an image acquirer 292, a memory 294, and a controller 296. The image acquirer 292 may include one or more processors. For example, the image acquirer 292 may include a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquirer 292 may be communicatively coupled to the charged particle detection device 244 of the beam tool 104 through a medium such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, or a combination thereof. In some embodiments, the image acquirer 292 may receive a signal from the charged particle detection device 244 and may construct an image. Thus, the image acquirer 292 may acquire an SCPM image of the wafer 230. The image acquirer 292 may also perform various post-processing functions, such as generating contours, superimposing indicators on the acquired image, etc. The image acquirer 292 may be configured to perform brightness and contrast adjustments of the acquired image. In some embodiments, the memory 294 may be a storage medium, such as a hard disk, a flash drive, a cloud storage, a random access memory (RAM), other types of computer-readable memory, etc. The memory 294 may be coupled to the image acquirer 292 and may be used to save the scanned raw image data as raw images and post-processed images. The image acquirer 292 and the memory 294 may be connected to the controller 296. In some embodiments, the image acquirer 292, the memory 294 and the controller 296 may be integrated together as a control unit.

[0064] In some embodiments, the image acquirer 292 may acquire one or more SCPM images of the wafer based on the imaging signal received from the charged particle detection device 244. The imaging signal may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image including multiple imaging regions. The single image may be stored in the memory 294. The single image may be an original image that can be divided into multiple regions. Each region may include an imaging region that includes a feature of the wafer 230. The acquired image may include multiple images of a single imaging region of the wafer 230 sampled multiple times in a time series. The multiple images may be stored in the memory 294. In some embodiments, the image processing system 290 may be configured to perform an image processing step using multiple images of the same position of the wafer 230.

[0065] In some embodiments, the image processing system 290 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain a distribution of the detected secondary charged particles (e.g., secondary electrons). The charged particle distribution data collected during the detection time window is combined with the corresponding scan path data of the beamlets 214, 216, and 218 incident on the wafer surface and can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the internal or external structure of the wafer 230, and thus can be used to reveal any defects that may be present in the wafer.

[0066] In some embodiments, the charged particles may be electrons. When the electrons of the primary charged particle beam 210 are projected onto the surface of the wafer 230 (e.g., detection points 270, 272, and 274), the electrons of the primary charged particle beam 210 may penetrate the surface of the wafer 230 to a certain depth and interact with the particles of the wafer 230. Some electrons of the primary charged particle beam 210 may interact elastically with the material of the wafer 230 (e.g., in the form of elastic scattering or collision), and may be reflected or rebounded from the surface of the wafer 230. The elastic interaction conserves the total kinetic energy of the interacting subject (e.g., the electrons of the primary charged particle beam 210), wherein the kinetic energy of the interacting subject is not converted into other forms of energy (e.g., thermal energy, electromagnetic energy, etc.). Such reflected electrons generated by the elastic interaction may be referred to as backscattered electrons (BSE). Some electrons of the primary charged particle beam 210 may interact inelastically with the material of the wafer 230 (e.g., in the form of inelastic scattering or collision). The inelastic interaction does not conserve the total kinetic energy of the interacting subject, wherein part or all of the kinetic energy of the interacting subject is converted into other forms of energy. For example, through inelastic interactions, the kinetic energy of some of the electrons of the primary charged particle beam 210 can cause electronic excitation and transition of material atoms. Such inelastic interactions can also generate electrons that leave the surface of the wafer 230, which can be referred to as secondary electrons (SE). The yield or emission rate of BSE and SE depends on, for example, the material being inspected and the landing energy of the electrons of the primary charged particle beam 210 landing on the material surface. The energy of the electrons of the primary charged particle beam 210 can be determined in part by its accelerating voltage (e.g., Figure 2 The number of BSE and SE may be more or less (even the same) than the injected electrons of the primary charged particle beam 210 , depending on the accelerating voltage between the anode and the cathode of the charged particle source 202 .

[0067] The images generated by the SEM can be used for defect inspection. For example, a generated image capturing a test device area of ​​a wafer can be compared with a reference image capturing the same test device area. The reference image can be predetermined (e.g., by simulation) and does not contain known defects. If the difference between the generated image and the reference image exceeds the tolerance level, potential defects can be identified. For another example, the SEM can scan multiple areas of a wafer, each area including a test device area designed to be the same, and generate multiple images capturing these test device areas manufactured. Multiple images can be compared to each other. If the difference between the multiple images exceeds the tolerance level, potential defects can be identified.

[0068] For ease of explanation and without ambiguity, electrons are used as examples in some descriptions herein. However, it should be noted that any charged particles may be used in any embodiment of the present disclosure, not limited to electrons. For example, the source in a charged particle beam tool may emit one or more charged particles, such as electrons, protons, ions, muons, or any other particles carrying an electric charge. In addition, some embodiments of the present disclosure may use photons instead of charged particles, such as visible light, UV, DUV, EUV, x-rays, or light within any other wavelength range. For example, in a photon embodiment, a secondary beam spot may refer to reflected, refracted, diffracted, or scattered light from a sample incident with a primary beam. Therefore, although the detector in the present disclosure may be disclosed for electron detection, some embodiments of the present disclosure may be directed to detecting other charged particles or photons.

[0069] Figure 3A Schematic diagram showing an exemplary structure of a detector 300A consistent with an embodiment of the present disclosure. The detector 300A can be configured as a charged particle detection device 244. Figure 3A In the embodiment, the detector 300A includes a sensor layer 301, a partial layer 302 and a readout layer 303. The sensor layer 301 may include a sensor chip composed of a plurality of sensor elements, including sensor elements 311, 312, 313 and 314. In some embodiments, a plurality of sensor elements may be arranged in a sensor element array, and each sensor element may have a uniform size, shape and arrangement. The detector 300A may have an arrangement relative to a coordinate axis reference system. The sensor layer 301 may be arranged along an xy plane. The sensor elements in the sensor layer 301 may be arranged along the x-axis and y-axis directions. The x-axis direction may also be referred to as the "horizontal" direction herein. The y-axis direction may also be referred to as the "vertical" direction herein. The detector 300A may have a layer structure, in which the sensor layer 301, the partial layer 302 and the partial layer are stacked along the z-axis direction. The z-axis direction may also be referred to as the "thickness" direction herein. The z-axis direction may be aligned with the incident direction of the charged particles toward the detector 300A.

[0070] Partial layer 302 may include multiple parts, including parts 321, 322, 323, and 324. The parts may include interconnects (e.g., wiring paths) configured to communicatively couple multiple sensing elements. The parts may also include switch elements that may control the communicatively coupling between the sensing elements. The parts may also include connection mechanisms (e.g., wiring paths and switch elements) between the sensing elements and one or more common nodes in the partial layer. For example, Figure 3AAs shown, portion 323 can be configured to be communicatively coupled to the outputs of sensing elements 311, 312, 313, and 314, as shown by the four dashed lines between sensor layer 301 and portion layer 302. In some embodiments, portion 323 can be configured to output the combined signals collected from sensing elements 311, 312, 313, and 314 as a common output. In some embodiments, a portion (e.g., portion 323) can be communicatively coupled to a sensing element (e.g., sensing elements 311, 312, 313, and 314) directly above the portion. For example, portion 323 can have a terminal grid configured to be connected to the outputs of sensing elements 311, 312, 313, and 314. In some embodiments, portions 321, 322, 323, and 324 can be provided in an array structure so that they have uniform size and shape and uniform arrangement. For example, portions 321, 322, 323, and 324 can be square. In some embodiments, isolation regions can be provided between adjacent portions to electrically insulate them from each other. In some embodiments, the portions may be arranged in an offset pattern, such as a tiled layout.

[0071] Readout layer 303 may include signal processing circuitry for processing the output of the sensing element. In some embodiments, a signal processing circuit may be provided that may correspond to each portion of portion layer 302. In some embodiments, a plurality of separate signal processing circuitry portions may be provided, including signal processing circuitry portions 331, 332, 333, and 334. In some embodiments, the signal processing circuitry portions may be arranged in a portion array having uniform size and shape and uniform arrangement. In some embodiments, the signal processing circuitry portions may be configured to connect to the outputs from the corresponding portions of portion layer 302. For example, as Figure 3A As shown, signal processing circuitry portion 333 may be configured to be communicatively coupled to the output of portion 323 , as indicated by the dashed line between portion layer 302 and readout layer 303 .

[0072] In some embodiments, readout layer 303 may include input and output terminals. The output of readout layer 303 may be connected to components for reading and interpreting the output of detector 300A. For example, readout layer 303 may be directly connected to a digital multiplexer, a digital logic block, a controller, a computer, etc.

[0073] The size of the portion and the number of sensing elements associated with the portion may vary. For example, while Figure 3A A 2x2 array of four sensing elements in one section is shown, but embodiments of the present disclosure are not limited thereto. In some embodiments of the present disclosure, a section may include a 3x3, 4x4, 5x5, 6x6, 2x4, or 1x6 array or any other suitable arrangement of sensing elements.

[0074] Although Figure 3A The sensor layer 301, the partial layer 302, and the readout layer 303 are shown as a plurality of separate layers, but it should be noted that the sensor layer 301, the partial layer 302, and the readout layer 303 do not have to be provided as separate substrates. For example, the wiring path of the partial layer 302 may be provided in a sensor chip including a plurality of sensing elements, or may be provided outside the sensor chip. The wiring path may be patterned on the sensor layer 301. In addition, the partial layer 302 may be combined with the readout layer 303. For example, a semiconductor chip including the wiring path of the partial layer 302 and the signal processing circuit of the readout layer 303 may be provided. Therefore, the structures and functions of the individual layers may be combined or divided.

[0075] In some embodiments, the detector may be provided in a dual die configuration. However, embodiments of the present disclosure are not limited thereto. For example, the functions of the sensor layer, the partial layer, and the readout layer may be implemented in one chip, or in a package that may contain one or more chips.

[0076] In some embodiments, the arrangement of sensor layer 301, partial layer 302, and readout layer 303 may correspond to each other in a stacked relationship. For example, partial layer 302 may be mounted directly on top of readout layer 303, and sensor layer 301 may be mounted directly on top of partial layer 302. The layers may be stacked so that a portion of partial layer 302 is aligned with a portion (e.g., portions 331, 332, 333, and 334) of signal processing circuitry of readout layer 303. In addition, the layers may be stacked so that one or more sensing elements in sensor layer 301 are aligned with a portion in partial layer 302. In some embodiments, a sensing element associated with a portion may be contained within the portion. For example, in a plan view of detector 300A, sensing elements (e.g., sensing elements 311, 312, 313, and 314) of a portion (e.g., portion 323) may fit within the boundaries of the portion. In addition, portions of partial layer 302 may overlap with portions of signal processing circuitry of readout layer 303. In this way, predefined areas may be established to associate sensing elements with portions and signal processing circuitry.

[0077] Figure 3B FIG. 2 shows an exemplary structure of a sensor surface 300B consistent with an embodiment of the present disclosure, which may form the surface of a charged particle detection device 244. The sensor surface 300B may be provided with a plurality of sensor element portions, including portions 340, 350, 360, and 370, which are indicated by dashed lines. For example, the sensor surface 300B may be Figure 3A Each portion may be capable of receiving at least a portion of a beam spot emitted from a specific location of the wafer 230, such as Figure 2 One of the secondary charged particle beams 236, 238, and 240 is shown.

[0078] Sensor surface 300B may include an array of sensor elements, including sensor elements 315, 316, and 317. In some embodiments, each of portions 340, 350, 360, and 370 may include one or more sensor elements. For example, portion 340 may include a plurality of first sensor elements, portion 350 may include a plurality of second sensor elements, and so on. The plurality of first sensor elements and the plurality of second sensor elements may be mutually exclusive. Figure 3B In the example embodiment of , each of the portions 340, 350, 360, and 370 includes a 6x6 array of sensing elements. In some embodiments, the sensing element may be a diode or any diode-like element that is capable of converting incident energy into a measurable signal. For example, the sensing element may include a PIN diode, an avalanche diode, an electron multiplier tube (EMT), or other components.

[0079] exist Figure 3B In some embodiments, region 380 may be provided between adjacent sensing elements. Region 380 may be an isolation region for isolating the sides or corners of adjacent sensing elements from each other. In some embodiments, region 380 may include an insulating material different from the sensing elements of sensor surface 300B. In some embodiments, region 380 may be provided in a square shape. In some embodiments, region 380 may not be provided between adjacent sides of the sensing elements.

[0080] In some embodiments, a field programmable detector array may be provided with sensor elements having switch regions integrated between the sensor elements. For example, a detector may be provided such as some examples discussed in PCT Application No. PCT / EP2018 / 074833 filed on September 14, 2018, the contents of which are incorporated herein by reference in their entirety. In some embodiments, switch regions may be provided between the sensor elements so that some or more of the sensor elements may be grouped when covered by the same charged particle beam spot. Circuitry for controlling the switch regions may be included in a readout layer (e.g., Figure 3A As used in the present disclosure, the expression "group" of sensing elements may refer to sensing elements associated with one beam spot (e.g., within the boundaries of the beam spot) projected on the detector surface. A "switch matrix" may refer to all or part of a network of switching elements within a detector architecture, configured to selectively connect various elements and wiring paths in the detector and associated control circuitry.

[0081] Figure 4 is a diagram illustrating an exemplary detector array 400 having switching elements, consistent with an embodiment of the present disclosure. Figure 4 The architecture can be used for single beam inspection tools or multi-beam inspection tools (e.g. Figure 2The detector array 400 may be Figure 3A For example, the detector array 400 may include a sensor layer (e.g., similar to Figure 3A sensor layer 301 in the embodiment of the present invention), a partial layer (e.g., similar to Figure 3A 302) and a readout layer (e.g., similar to Figure 3A The sensor layer of the detector array 400 may include a plurality of sensor elements, including sensor elements 311, 312, 313, and 314. In some embodiments, each sensor element of the detector array 400 may have a uniform size, shape, and arrangement. The sensor elements of the detector array 400 may generate a current signal commensurate with the charged particles (e.g., emitted electrons) received in the active region of the sensor element. The "active region" herein may refer to a region where the sensor element has a radiation sensitivity above a predetermined threshold.

[0082] Some layers of the detector array 400 may include a substrate (e.g., a semiconductor substrate, Figure 4 (not shown), the substrate includes one or more wiring paths 402. The wiring paths 402 can be configured to communicatively couple the sensing elements of the detector array 400. Figure 4 As shown, the detector array 400 includes a portion 321 having 4×4 sensing elements, including sensing elements 311, 312, 313, and 314. Figure 4 In, a partial layer of the detector array 400 may include an inter-element switch element 315 between any two adjacent sensing elements. A partial layer of the detector array 400 may also include an inter-element switch element 315 that is communicatively coupled to the edges of adjacent sensing elements. The wiring path 402 may be configured to be communicatively coupled to the outputs of the sensing elements (e.g., sensing elements 311, 312, 313, and 314) in portion 321. For example, the wiring path 402 may have a terminal grid (shown as circular black dots in the center of the sensing elements) that is configured to connect to the outputs of the sensing elements 311, 312, 313, and 314. In some embodiments, the wiring path 402 may be disposed in a partial layer of the detector array 400. In Figure 4 In FIG. 4 , the wiring path 402 is communicatively coupled to the above-mentioned sensing elements (e.g., sensing elements 311, 312, 313, and 314). Figure 4 In the embodiment of the present invention, the element bus switch element 316 can be disposed between the output of the sensing element and the wiring path 402. In some embodiments, the element bus switch element 316 can be disposed in a partial layer of the detector array 400.

[0083] In some embodiments, the wiring paths 402 may include conductive material lines, flexible lines, bonding wires, etc. printed on the substrate. In some embodiments, switching elements may be provided so that the outputs of the individual sensing elements may be connected or disconnected from the common output of the portion 321. In some embodiments, some layers of the detector array 400 may also include corresponding circuits for controlling the switching elements. In some embodiments, the switching elements may be provided in a separate switching element matrix, which itself may contain circuits for controlling the switching elements.

[0084] The readout layer of the detector array 400 may include a signal conditioning circuit for processing the output of the sensing element. In some embodiments, the signal conditioning circuit may convert the generated current signal into a voltage that may represent the intensity of the received beam spot, or may amplify the generated current signal into an amplified current signal. The signal conditioning circuit may include, for example, an amplifier 404 and one or more analog switching elements. The amplifier 404 may be a high-speed transimpedance amplifier, a current amplifier, etc. Figure 4 In the embodiment, amplifier 404 can be communicatively coupled to the common output terminal of portion 321 for amplifying the output signal of the sensing element of portion 321. In some embodiments, amplifier 404 can be a single-stage or multi-stage amplifier. For example, if amplifier 404 is a multi-stage amplifier, it can include a preamplifier and a postamplifier, or a pre-stage and a post-stage, etc. In some embodiments, amplifier 404 can be a variable gain amplifier, such as a variable gain transimpedance amplifier (VGTIA), a variable gain charge transfer amplifier (VGCTA), etc. The regulation circuit can be coupled to a signal path, which can include, for example, an analog-to-digital converter (ADC) 406. In the embodiment, amplifier 404 can be a single-stage or multi-stage amplifier. Figure 4 406 can be communicatively coupled to the output of a conditioning circuit (e.g., including amplifier 404) to convert the analog output signal of the sensing element of portion 321 into a digital signal. The readout layer of detector array 400 can also include other circuits for other functions. For example, the readout layer of detector array 400 can include a switch element actuation circuit that can control the switch elements between the sensing elements. For ease of explanation and without ambiguity, the signal path between the sensing element and ADC 406 can be referred to as an "analog signal path." For example, Figure 4The analog signal path in the detector 400 includes the above-mentioned signal conditioning circuit (e.g., including amplifier 404). The input of the analog signal path is communicatively coupled to the sensing element, and the output of the analog signal path is communicatively coupled to ADC 406. The signal path between the sensing element and the readout layer can be referred to as a "signal readout path" and can be the same as or different from the analog signal path. For example, the signal readout path can include an analog signal path or multiple analog signal paths, and can be further extended into the readout layer of the detector 400, such as to a digital multiplexer 408.

[0085] In some embodiments, ADC 406 may include an output that is communicatively coupled to a component (e.g., a component internal or external to a readout layer of detector array 400) for reading and interpreting the digital signal converted by ADC 406. Figure 4 4, ADC 406 is communicatively coupled to digital multiplexer 408. In some embodiments, digital multiplexer 408 can be disposed in a readout layer of detector array 400. Digital multiplexer 408 can receive multiple input signals and convert them into output signals. The output signal of digital multiplexer 408 can be converted back into multiple input signals. The output signal of digital multiplexer 408 can be further transmitted to a data processing stage (e.g., Figure 2 Image processing system 290 in.

[0086] In some embodiments of the present disclosure, the detector 400 may include additional layers of switching elements, such as an interconnect layer 416, which communicatively couples the outputs of the signal processing circuits to each other. The signal processing circuits may include analog signal paths. Figure 4 As shown, interconnect layer 416 includes interconnect switch elements that are communicatively coupled to the outputs of analog signal paths of detector array 400. For example, interconnect switch elements 420-423 can communicatively couple the outputs of adjacent analog signal paths. Detector array 400 includes analog signal path 405 associated with portion 321, which starts from the output of portion 321 and ends at the input of interconnect layer 416.

[0087] exist Figure 4405. In some embodiments, the switching element 408 may communicatively couple the output of the portion 321 to the input of the analog signal path 405, and the switching element 410 may communicatively couple the output of the analog signal path 405 to the input of the interconnect layer 416 (e.g., input / output point 426 or "I / O point" 426). If the analog signal path 405 is not selected for use, the switching elements 408 and 410 may be configured to be communicatively disconnected. For example, a charged particle beam may hit some or all of the sensing elements of the portion 321, but the detection signal of the portion 321 may be redirected to another analog signal path corresponding to another portion of the detector array 400, as discussed further below. In this case, the analog signal path 405 may be disconnected due to not being selected. In some embodiments, if the sensing elements of the portion 321 are not hit by any charged particles and the analog signal path 405 is not selected for use (e.g., to process signals from other portions), in addition to the communication disconnection of the switching elements 408 and 410, the amplifier 404 may also be disabled to reduce power consumption. When switch elements 408 and 410 are communicatively disconnected, analog signal path 405 (including amplifier 404 ) may be effectively disabled from detector array 400 .

[0088] The switch matrix includes, for example, inter-element switch elements 315, element bus switch elements 316, and interconnect switch elements 420-423, and can be configured to route signals from the sensor elements to the readout layer of the detector array 400 through various signal readout paths. For example, when only one beam spot is incident on the portion 321, the sensor elements can be coupled to the readout layer through the element bus switch element 316 and the switch elements 408-410. For example, if it has been previously determined that the beam spot is incident on all sensor elements in the portion 321 (e.g., during picture mode), the entire portion can be coupled to the signal readout path through the element bus switch element at each sensor element in the portion 321. The inter-element switch elements 315 between the sensor elements in the portion 321 can be kept open to reduce parasitic parameters, such as series resistance and parasitic capacitance. For example, if it is determined that sensor elements 311 and 312 are receiving a portion of the beam spot while the remaining sensor elements of portion 321 are not receiving it, only sensor elements 311-312 can be connected by closing their element bus switch elements 316, while the remaining sensor elements can be disconnected by keeping their own element bus switch elements 316 in an open state.

[0089] At the same time, sensing elements from adjacent sections may be coupled to a common signal readout path at interconnect layer 416 through interconnect switches 420-423. Alternatively, sensing elements from adjacent sections may be coupled to sensing elements within section 321 by closing inter-element switch elements 315 therebetween.

[0090] If it is determined that two different beam spots are incident on two different parts of portion 321, the signals from the two beam spots must be routed along different signal readout paths to distinguish them. In this case, it is not possible for the two parts to be coupled to analog signal path 405. For example, the first beam spot may be incident on sensing elements 311-312 and Figure 4 The second beam spot may be incident on the entire row 317 including the sensing elements 313 and 314 as well as the adjacent portion to the left of the middle portion 321 (not shown). Figure 4 The adjacent section (not shown) to the right of the middle section 321. If both sets of sensing elements were routed through the analog signal path 405, their signals would be indistinguishable. Therefore, at least one section may be connected to adjacent sections that share a common beam spot.

[0091] Figure 4 4. The interconnection switch element 423 may be opened to disconnect the adjacent portion from the signal readout path including the analog signal path 405. At the same time, the row 317 may be coupled to the analog signal path 405 through its element bus switch element 316. The analog signal path 405 may be connected to the analog signal path of the adjacent portion on the right side by, for example, closing the interconnection switch element 421. Thus, the row 317 may be coupled to its adjacent portions without closing the inter-element switch element 315 between them.

[0092] The decision to route the two portions in the above example manner may be determined based on, for example, the desired value of minimizing parasitic parameters in the system. For example, if a parallel path along the element bus switch element 316 is preferred over a serial path along the inter-element switch element 315, then a route may be determined such that fewer inter-element switch elements 315 are connected to the system. The overall measured value of the parasitic parameters may be considered when determining the optimal signal readout path.

[0093] Additional details of the detector array 400 may be found in U.S. Provisional Patent Application No. 63 / 019,179, which is incorporated herein by reference in its entirety.

[0094] Figure 5 5 is a diagram showing a cross-sectional view of a layer structure of a detector 500 consistent with an embodiment of the present disclosure. The detector 500 may be configured as a charged particle detection device 244 in a charged particle beam tool 104, such as Figure 2As shown. The detector 500 may be configured to have a plurality of layers stacked in a thickness direction, the thickness direction being substantially parallel to the incident direction of the charged particle beam. In some embodiments, the detector 500 may be configured as some of the examples discussed in PCT Application No. PCT / EP2018 / 074834 filed on September 14, 2018, the contents of which are incorporated herein by reference in their entirety.

[0095] exist Figure 5 In the embodiment, the detector 500 may include a sensor layer 510 and a circuit layer 520. In some embodiments, the sensor layer 510 may represent Figure 3A The sensor layer 301 in FIG. 5 , and the circuit layer 520 may represent Figure 3A The circuit layer 520 may include a portion of the layer 302 and the readout layer 303. For example, the circuit layer 520 may include interconnects (e.g., metal lines) and various electronic circuit elements. As another example, the circuit layer 520 may include a processing system. The circuit layer 520 may also be configured to receive an output current detected in the sensor layer 510. In some embodiments, the sensor layer 510 may represent Figure 3A The sensor layer 301 and the partial layer 302 in FIG. 5 , and the circuit layer 520 may represent Figure 3A In some embodiments, the detector 500 may further include layers other than the sensor layer 301 , the partial layer 302 , and the readout layer 303 .

[0096] In some embodiments, the sensor layer 510 may be provided with a sensor surface 501 for receiving incident charged particles. Sensor elements may be provided in the sensor layer 510, including sensor elements 511, 512, and 513 (distinguished by dashed lines). For example, the sensor surface 501 may be similar to Figure 3B The sensor surface 300B in Figure 5 In the embodiment, a switch element may be provided between the sensor elements adjacent to each other in the horizontal direction in the cross-sectional view, including switch elements 519 and 521. The switch elements 519 and 521 may be embedded in the sensor layer 510. In some embodiments, the sensor elements 511, 512, and 513 may be Figure 4 Among the sensor elements (e.g., sensor elements 311, 312, 313, and 314) of the detector array 400, the switch elements 519 and 521 may be Figure 4 Among the switching elements between the sensing elements of the detector array 400.

[0097] In some embodiments, the sensing elements 511, 512, 513 may be separated by an isolation region (shown by a dotted line) extending in the thickness direction. For example, the edges of the sensing elements 511, 512, 513 parallel to the thickness direction may be separated by the isolation region (e.g., Figure 3BThe regions 380) in are isolated from each other.

[0098] In some embodiments, the sensor layer 510 can be configured as one or more diodes, wherein the sensing elements 511, 512, and 513 are similar to Figure 3B The sensor elements 315, 316 and 317 of the sensor layer 510 can be configured as transistors (e.g., MOSFETs). Each of the sensor elements 511, 512, 513 can include an output for electrically connecting to the circuit layer 520. For example, the output can be integrated with the switch elements 519 and 521, or they can be provided separately. In some embodiments, the output can be integrated in the bottom layer (e.g., metal layer) of the sensor layer 510.

[0099] although Figure 5 The sensing elements 511, 512, and 513 are depicted as separate units in cross section, but this division may not actually be physical. For example, the sensing elements of the detector 500 can be formed by a semiconductor device that constitutes a PIN diode device, which can be manufactured as a substrate with multiple layers, including a P-type region, an intrinsic region, and an N-type region. In such an example, the sensing elements 511, 512, 513 can be continuous in the cross-sectional view. In some embodiments, the switching elements (e.g., switching elements 519 and 521) can be integrated with the sensing elements.

[0100] In some embodiments, the switch element may be integrated within the sensor layer, integrated within other layers, or may be partially or fully disposed in an existing layer. In some embodiments, for example, the sensor layer may contain wells, trenches, or other structures in which the switch element is formed.

[0101] In some embodiments, the switch elements (eg, switch elements 519 and 521) of the detector 500 may be disposed outside the sensor layer 510. For example, the switch elements may be embedded in the circuit layer 520 ( Figure 5 In some embodiments, the switch elements (eg, switch elements 519 and 521) of detector 500 may be formed in separate dies (eg, switch dies). Figure 5 ) may be sandwiched between the sensor layer 510 and the circuit layer 520 and be communicatively connected thereto.

[0102] Figure 6 is a diagram showing a cross-sectional view of a sensing element 512 of a detector 500 consistent with an embodiment of the present disclosure. Figure 6 In the embodiment, the sensing element 512 may include a P-well and an N-well for forming a switching element and other active or passive elements that may be communicatively coupled to other components of the sensor layer 510 or the circuit layer 520. Figure 6Only one complete sensing element 512 is shown, but it is understood that the sensor layer 510 may be composed of multiple sensing elements similar to the sensing element 512 (eg, sensing elements 511 and 513), which may be continuous in the cross-sectional view.

[0103] In some embodiments, the sensing element 512 may include a diode device having a surface layer 601, a P-type region 610, a P-epitaxial region 620, an N-type region 630, and other components. The surface layer 601 may form a detection surface (e.g., an active region) of a detector that receives incident charged particles. For example, the surface layer 601 may be a metal layer (e.g., formed of aluminum or other conductive materials). On the opposite side of the surface layer 601, an electrode 650 may be provided as a charge collector. The electrode 650 may be configured to output a current signal representing the number of charged particles received in the active region of the sensing element 512.

[0104] like Figure 6 As shown, the switch elements 519 and 521 may be formed by metal oxide semiconductor (MOS) devices. Figure 6 A plurality of MOS devices are formed on the back side of the N-type region 630, and the back side of the N-type region 630 can be connected to Figure 5 The sensor layer 510 in the embodiment of the present invention is contacted. As an example of a MOS device, a deep P well 641, an N well 642, and a P well 643 may be provided. In some embodiments, the MOS device may be manufactured by etching, patterning, and other processes and techniques. It is understood that various other devices may be used, such as bipolar semiconductor devices, etc., and the device may be manufactured by various processes.

[0105] During operation of the sensing element 512, when charged particles (e.g. Figure 2 When the secondary charged particle beam 236, 238 and 240 in the sensor element 512 strikes the surface layer 601, the body of the sensing element 512 (including, for example, a depletion region) may be filled with charge carriers generated by the striking charged particles. Such a depletion region may extend through at least a portion of the volume of the sensing element. For example, the charged particles may be electrons, and the striking electrons may create and excite electron-hole pairs in the depletion region of the sensing element. The excited electrons in the electron-hole pairs may have additional energy so that they may also generate new electron-hole pairs. The electrons generated by the striking charged particles may contribute to the signal generated in each sensing element.

[0106] refer to Figure 6, the depletion region in the sensing element 512 may include an electric field between the P-type region 610 and the N-type region 630, and the electrons and holes may be attracted to the P-type region 610 and the N-type region 630, respectively. When the electron reaches the P-type region 610 or when the hole reaches the N-type region 630, a detection signal may be generated. Therefore, when the charged particle beam is incident on the sensing element 512, the sensing element 512 may generate an output signal, such as a current. A plurality of sensing elements may be connected, and a sensing element group may be used to detect the intensity of the charged particle beam spot. When the charged particle beam spot covers a plurality of adjacent sensing elements (e.g., sensing elements 511, 512, and 513), the sensing elements may be grouped together ("merged") to collect current. For example, the sensing elements may be merged by opening a switching element (e.g., switching elements 519 and 521) between the sensing elements. Signals from the sensing elements in the group may be collected and sent to a signal conditioning circuit connected to the group. The number of sensing elements in a group can be any number that is associated with the size and shape of the beam spot. The number can be 1 or greater than 1.

[0107] In some embodiments, the detector can be configured so that individual sensing elements can communicate with external components through, for example, signal or data lines and address signals. The detector can be configured to actuate a switching element so that two or more sensing elements can be combined and their output currents or voltages can be combined. Figure 5-Figure 6 As shown, by utilizing the switch element design between the sensing elements, no physical isolation area (e.g., Figure 3B The sensing element is provided in the region 380 in the surface layer 601. Therefore, when the sensing element 512 is activated, all areas under the surface layer 601 can become active. When no physical isolation area is provided between adjacent sensing elements, the dead space between them can be minimized or eliminated.

[0108] Figure 7 is a diagram showing an exemplary cross-sectional arrangement of a detector 700 consistent with an embodiment of the present disclosure. For example, the detector 700 may be Figure 3A Detector 300A in Figure 4 The detector array 400 or Figure 5 An embodiment of the detector 500 in FIG. Figure 7 As shown, the detector 700 may include a plurality of sensing elements, including sensing elements 701, 702, 703, 704, 705, and 706. In some embodiments, the plurality of sensing elements may be part of a sensor layer, which may form a Figure 2 The detection surface of the charged particle detection device 244 in Figure 3B The sensor layer may include switching elements between adjacent sensing elements (e.g., similar to Figure 6519 and 521 in the embodiment of the present invention), including inter-element switch elements 711, 712 and 713. In some embodiments, when conducting, the switch element can be configured to combine two or more adjacent sensing elements together.

[0109] exist Figure 7 In the embodiment, the detector 700 may include multiple parts (e.g., similar to Figure 3A Each portion may include one or more sensing elements, and wiring paths between the sensing elements (e.g., similar to Figure 4 In some embodiments, the wiring path may include a common line or a shared signal path. For example, Figure 7 As shown, wiring path 721 can be communicatively connected to sensing elements 701, 702 and 703, and common output terminal 728. Wiring path 721, sensing elements 701-703 and common output terminal 728 can belong to a first portion. Line path 722 can be communicatively connected to sensing elements 704, 705 and 706 and common output terminal 729. Line path 722, sensing elements 704-706 and common output terminal 729 can belong to a second portion. The output (e.g., output 719) of a sensing element (e.g., sensing element 706) can be communicatively coupled to a corresponding line path (e.g., line path 722) via an element bus switch element (e.g., element bus switch element 720). In some embodiments, element bus switch element 720 can use a circuit similar to Figure 6 In some embodiments, when the sensing element 706 is in an inactive state, the element bus switch element 720 may be disconnected to reduce noise, parasitic capacitance or other technical effects from the sensing element 706.

[0110] Figure 7 In the embodiment of the present invention, each part (e.g., the first part including the sensing elements 701-703 or the second part including the sensing elements 704-706) can be configured to output electrical signals to the signal processing circuit and other circuit elements. For example, the wiring path 722 can output electrical signals to the signal processing circuit system 730 through the common output terminal 729.

[0111] The signal processing circuit system 730 may include one or more signal processing circuits for processing the electrical signal output by the wiring path 722. For example, the signal processing circuit system 730 may include a preamplifier 731, a postamplifier 732, and a data converter 733. For example, the preamplifier 731 may be a transimpedance amplifier (TIA), a charge transfer amplifier (CTA), a current amplifier, etc. The postamplifier 732 may be a variable gain amplifier (VGA), etc. The data converter 733 may be an analog-to-digital converter (ADC), which can convert an analog voltage or an analog current into a digital value. In some embodiments, the preamplifier 731 and the postamplifier 732 may be combined into a single amplifier (e.g., Figure 4 404 in the amplifier), and the data converter 733 may include Figure 4 ADC 406 in.

[0112] The detector 700 may include a digital switch 740. In some embodiments, the digital switch 740 may include a matrix of switch elements. In some embodiments, the digital switch 740 may include a multiplexer (e.g., Figure 4 For example, the multiplexer may be configured to receive a first number of inputs and generate a second number of outputs, where the first number and the second number may be the same or different. The first number may correspond to a parameter of the detector 700 (e.g., the total number of parts), and the second number may correspond to Figure 1-Figure 2 The parameters of the beam tool 104 (e.g., from Figure 2 The digital switch 740 may communicate with external components via data lines and address signals. In some embodiments, the digital switch 740 may control data read / write. The digital switch 740 may also include circuits for controlling inter-element switch elements (e.g., inter-element switch elements 711, 712, and 713). Figure 7 In the embodiment, the digital switch 740 can generate an output signal through multiple data channels, including data channels 751, 752, and 753. In some embodiments, the data channels of the digital switch 740 can be further connected to other components (e.g., relays, etc.). Therefore, multiple parts of the detector 700 can act as independent data channels for the detector signal.

[0113] It is worth noting that in Figure 7 Various components are inserted at various stages in the representation of the detector 700. In some embodiments, one or more of the above components of the detector 700 may be omitted. In some embodiments, other circuits may be provided to achieve other functions. For example, a switch element actuation circuit ( Figure 7(not shown) to control the inter-element switch elements (e.g., inter-element switch elements 711, 712, and 713) used to connect the sensing elements. In some embodiments, an analog output line ( Figure 7 732 ), which can be read through an analog path. For example, the analog output line can be parallel to the data converter 733 to receive the output of the post amplifier 732. For another example, the analog output line can replace the data converter 733.

[0114] Figure 8 8 is a diagram showing another exemplary partial arrangement of detector 800 consistent with embodiments of the present disclosure. Detector 800 can be similar to detector 700, except that sensing elements associated with the portions (e.g., sensing elements 704, 705, and 706) can be communicatively coupled to associated wiring paths (e.g., wiring paths 722) via common wiring paths (e.g., common wiring paths 819) and common switch elements (e.g., common switch elements 820). In some embodiments, common switch elements 820 can be communicatively coupled to associated wiring paths (e.g., wiring paths 722) using common wiring paths (e.g., common wiring paths 819) and common switch elements (e.g., common switch elements 820). Figure 6 The switching elements 519 and 521 described in the embodiment of the present invention can be realized by the technology of the switching elements 519 and 521 described in the embodiment of the present invention. Figure 8 As shown, if a charged particle beam is incident on sensing elements 704, 705, and 706, sensing elements 704, 705, and 706 can generate detection signals. Sensing element 705 can directly output its detection signal to a common wiring path 819. Sensing elements 704 and 706 can route their detection signals to sensing element 705 through inter-element switch elements 712 and 713, respectively, and the switch elements 712 and 713 can be further routed to the common wiring path 819 via sensing element 705. Such a design can simplify the manufacture of the detector. In contrast, designs that use multiple wiring paths and switch elements between sensing elements and parts (for example, Figure 7 The design of the detector 700 in FIG. 7A ) can provide configuration flexibility for grouping sensing elements because the output of a portion is not fixed to any particular sensing element in the portion (e.g., Figure 8 In addition, such as Figure 7 The design of the detector 700 in may enhance the simplicity of reading the output of each sensing element. In order to obtain the beam projection of the secondary electron beam, it may be advantageous to read out the output of each sensing element in order to obtain an image of the projection pattern.

[0115] In some embodiments of the present disclosure, Figure 7 and Figure 8 The configuration may include interconnect layers, such as Figure 4 416 in. Such a configuration may be found in the aforementioned U.S. Provisional Patent Application No. 63 / 019,179.

[0116] Fig. 9is a diagram showing a detection system 900 consistent with an embodiment of the present disclosure. In some embodiments, the detection system 900 may be Figure 2 Detection system 900 may include a sensor element 902 (e.g., similar to Figure 3A-Figure 8 ) and processing circuit 940 (e.g., similar to Figure 7-Figure 8 Processing circuitry 940 may be communicatively coupled to a digital interface 950 (e.g., similar to Figure 7-Figure 8 The sensing element 902 may form a sensor surface (e.g., Figure 3B sensor surface 300B), and may be segmented into a plurality of portions (e.g., similar to Figure 3A-3B or Figure 7-Figure 8 The processing circuit 940 may include a first processing circuit array 910 (eg, including) for processing the output of the sensor element 902. Figure 7-Figure 8 ), a second processing circuit array 920 (e.g., including a preamplifier 731 in FIG. 1 ) for providing gain and offset control Figure 7-Figure 8 ), and an ADC array 930 (e.g., including a post-amplifier 732 in FIG. 1 ) for converting analog signals into digital signals. Figure 7-Figure 8 The first processing circuit array 910 and the second processing circuit array 920 may constitute a signal conditioning circuit in the processing circuit 940, each portion of the processing circuit 940 may be communicatively coupled to a portion of the sensor element 902, and the sensor element 902 may be communicatively coupled to the units of the first processing circuit array 910, the units of the second processing circuit array 920, and the units of the ADC array 930 in sequence to form a signal path (e.g., signal path 960). Such a signal path may receive an output signal from the sensor element portion 902 and generate a charged particle detection current, which represents the intensity of at least a portion of the charged particle beam spot formed on the sensor element portion 902. The charged particle detection data may be output to the digital interface 950. Fig. 9 , signal path 960 includes an analog signal path 970 that includes cells of the first processing circuit array 910 and cells of the second processing circuit array 920 .

[0117] The digital interface 950 may include a controller 904. The controller 904 may communicate with the ADC array 930, the second processing circuit array 920, and the sensor element 902. The digital interface 950 may also receive data from the deflection and image control unit ( Fig. 9 The transceiver may include a transmitter 906 and a receiver 908. In some embodiments, the controller 904 may control image signal processing of the detection system 900.

[0118] Fig. 10A FIG. 1 shows a detector 1000 surface and picture mode operation according to some embodiments of the present disclosure. The detector 1000 may correspond to Figure 2 The detection surface or reference of the charged particle detection device 244 Figure 3A-Figure 9 Any detector described. The detection surface may include an array of sensor elements, such as PIN diode elements. In some embodiments, the sensor elements may include, for example, avalanche diodes, electron multiplier tubes (EMTs), or other components. Each sensor element (e.g., a PIN diode) may correspond to a separate sensor element 1015. Alternatively, a single sensor element (e.g., a PIN diode) may be pixelated into separate sensor elements 1015 in various ways. For example, a semiconductor detection unit may be divided by an internal field generated due to an internal structure. In some embodiments, there may be a physical separation between adjacent sensor elements, such as by a region 1080 provided between adjacent sensor elements. Region 1080 may be an isolation region for isolating the edges or corners of adjacent sensor elements from each other. In some embodiments, region 1080 may include an insulating material different from the sensor element 1015 on the sensor surface of detector 1000. In some embodiments, region 1080 may be arranged in a square shape. In some embodiments, region 1080 may not be arranged between adjacent edges of the sensor element.

[0119] like Fig. 10A As shown, there can be a region of interest 1005a on the surface of the detector 1000. A pixelated array of sensing elements on the detector can constitute the region of interest 1005a. In some embodiments, the detector 1000 can be implemented as a single beam system. In some embodiments, the detector 1000 can be implemented as a multi-beam system. In some embodiments, more sensing elements (e.g., Fig. 10B As shown in area 1005b). Fig. 10A As shown by the light and dark areas in FIG. , the sensing element 1015 can be functionally divided into portions of, for example, a 4x4 array, such as Figure 4 A secondary beam spot 1008 may be formed on the surface of the detector 1000. The beam spot 1008 may have a well-defined center or trajectory. Although the beam spot 1008 is shown as having an approximately circular shape, the distribution of secondary particles falling within the beam spot 1008 may have an irregular shape and may deviate significantly from a circle (e.g., Fig. 10BIn addition, the distribution of particles received within the beam spot 1008 may follow various patterns or may be random. Typically, particles are not distributed in a Gaussian pattern within the beam spot. However, certain areas of the beam spot 1008 may receive more secondary particles than other areas. Secondary particles may be generated in response to the primary beam being incident on the sample and may be emitted at various energies and emission angles. Secondary particles may form a beam (e.g., a secondary electron beam). The secondary electron beam may be incident on a detector and may form a beam spot 1008.

[0120] Picture mode operation of a charged particle beam device and a charged particle detector (sometimes referred to as a charged particle beam detector) can be used to obtain a high resolution image of a beam spot 1008 on the detector 1000, which can indicate beam spot parameters, such as size, shape, and intensity distribution. It can also indicate the conditions of the beam, such as alignment, divergence, angle of incidence on the sample surface, etc., as well as other conditions of the charged particle beam device and its various components. These parameters and conditions can be used for alignment, tuning, or other maintenance procedures of the charged particle beam device. The high resolution picture mode image can also be used to determine appropriate groupings of sensor elements 1015 for other "beam mode" operations. In beam mode, groups of sensor elements can be coupled to a common signal readout path, such as through an inter-element switch element or an element bus switch element ( Fig. 10A 1008) to collect secondary particle detection signals of the beam spot 1008. At the same time, adjacent sensing elements 1015 outside the group can be disconnected from the signal readout path to improve parasitic parameters and prevent unwanted signals such as thermal noise and crosstalk from adjacent beams. Therefore, the ideal grouping of sensing elements 1015 can include those sensing elements 1015 that receive a large number of charged particles from the beam spot 1008 and exclude those sensing elements 1015 that do not receive a large number of charged particles.

[0121] Using the picture mode image, a boundary 1010 can be determined. The boundary 1010 can be provided to include a sensing element that receives charged particles from the secondary electron beam. The sensing elements included within the boundary 1010 can be at least partially covered by the same charged particle beam spot 1008. The boundary 1010 can include the boundary of the beam spot 1008. As used herein, the term "boundary" can refer to the periphery of the beam spot encoded by the detector. The shape of the boundary can conform to the shape of each sensing element 1015. "Boundary" can refer to the outline of the beam spot. The boundary of the beam spot 1008 can more closely correspond to the natural shape formed by the charged particles of the beam striking the surface. For example, the beam spot can have a border that is approximately circular and a more square border around the border. In some embodiments, the boundary and the boundary can coincide.

[0122] The determination of the beam spot boundary 1010 can be based on the acquired beam spot projection pattern. The beam spot projection pattern can be acquired by continuously reading the individual outputs of each sensor element that may be included in the detector. In some embodiments, the boundary 1010 can be determined by image processing of a high-resolution picture mode image. In the picture mode, an image of the detector surface can be acquired, and the boundary 1010 or sensor element group associated with the beam spot 1008 can be determined. Note that since the sensor element group is identified by reference to the imaginary boundary, similar numbers can interchangeably refer to the sensor element group or the boundary containing the group. During the picture mode, the detection system can be dedicated to the projection pattern acquisition. For example, it can be determined that electrons are received in the sensor element group 1015 on the surface of the detector 1000. The group of sensor elements can be continuous and can have a substantially circular shape. The boundary 1010 can be drawn around the sensor elements in the group. Each sensor element within the boundary can at least partially receive electrons within the sensor element surface area. The sensor elements included in the group can be used for subsequent processing, such as beam spot intensity determination (e.g., using beam mode). Other processing in picture mode may include pattern identification, edge extraction, etc.

[0123] In some embodiments, the beam spot 1008 may deviate from a circular shape in various ways. For example, the beam spot 1008 may have an elongated shape, or an irregular shape, such as a starburst. In addition, the boundary of the beam spot does not necessarily represent the entire spatial range of the secondary particles associated with the beam spot. Instead, the boundary may indicate an area where a threshold concentration of secondary particles can be found. For example, the actual distribution of secondary particles may gradually decrease in the radial direction from the central portion of the beam spot 1008 and extend to the boundary of the beam spot 1008 and the area outside the boundary 1010. These external secondary particles can be ignored from the beam spot because, for example, their concentration is too low to collect them. For example, the increase in collection efficiency that may be brought about by collecting secondary particles may be offset by the risk of crosstalk from adjacent beams. Therefore, the grouping of sensor elements 1015 within the boundary 1010 may include only those sensor elements 1015 that receive a large number of charged particles from the beam spot 1008. In some embodiments, the grouping of sensor elements 1015 may include only those sensor elements 1015 that receive more than a predetermined amount of radiation. The predetermined amount may be set by experimentation, simulation, operator preference, or any other parameter that can be configured in advance or on the fly.

[0124] After the boundaries of the beam spot are determined in picture mode 1010, the sensing elements within the boundaries can be grouped together during beam mode operation (e.g., SEM inspection or other charged particle beam processes). The grouped elements can be functionally coupled to a common signal readout path, such as by an inter-element switch element, an element bus switch element, or an interconnect switch element, as described with respect to FIG. Figure 4 Said Fig. 10A1008). The measurements at the grouped sensing elements within the boundary 1010 are determined to correspond to the measurements of the secondary beam spot 1008. Further details of picture mode and beam mode operation can be found in U.S. Provisional Application No. 63 / 130,576, the entire contents of which are incorporated herein by reference.

[0125] As mentioned above about Figure 4 As discussed above, there are many ways to configure the signal readout path in detector 1000. For example, if detector 1000 is implemented in a single beam system, each sensing element can be switched via an element bus switch element (e.g. Figure 4 316 in the figure) is coupled to the signal readout path. It may not be necessary to use or even include inter-element switching elements 315 or interconnect layers 416. Sensing elements that are not grouped with a single beam may be disconnected to reduce parasitic parameters in the detector. If the detector 1000 is implemented in a multi-beam system, an optimal configuration of the signal readout path may be determined that can distinguish each beam while minimizing parasitic parameters.

[0126] During the use of a charged particle beam device, beam spot parameters may drift and change. For example, the beam spot may change shape, the location of its center of mass on the detector may shift, or its overall size may increase or decrease. These changes can be difficult to predict, especially when the beam shape is related to the Fig. 10A . If the beam spot 1008 changes its shape, size, position or other parameters, the boundary 1010 may no longer coincide with the actual sensing element 1015 that receives the secondary particles. This mismatch creates two problems. First, since some of the sensing elements that receive the secondary particles of the beam are not coupled to the group of sensing elements located within the boundary 1010, the measured beam intensity is lost. Therefore, any secondary particles received by these ungrouped sensing elements may not be recorded. Second, other sensing elements coupled to the group may not receive secondary particles, so they may not provide useful information. These other sensing elements may only increase parasitic parameters, reduce data processing speed and analog signal bandwidth, or may have other harmful effects.

[0127] Fig. 10B Some embodiments of the present disclosure are shown Fig. 10A Here, region 1005b is shown, which may be larger than Fig. 10Aregion of interest 1005a. In some embodiments of the present disclosure, region 1005b may encompass the entire surface of the detector 1000. Four beam spots 1008a-d are incident on different portions of region 1005b of the detector 1000. Here, a 2x2 beam spot array is shown, but in some embodiments of the present disclosure, any suitable beam spot arrangement is contemplated. For example, the beam spots 1008 may be arranged in a 3x3, 5x5, 2x10 array, or any other arrangement. The beam spots may have a more complex or irregular arrangement. The beam spots 1008a-d are incident on different portions of the detector 1000, respectively. Each beam spot 1008a-d is assigned a group of sensing elements 1015 bounded by boundaries 1010a-d. Each beam spot 1008a-d overlaps with its grouping boundary 1010a-d, but does not coexist with its grouping boundary 1010a-d. It is worth noting that although Fig. 10B 1008a-d are depicted as being identical, but this is not necessarily the case. Each boundary 1010 may be determined independently to fit each beam spot 1008, for example, according to a picture mode imaging operation. However, due to subsequent drift, or due to an initial picture mode process that produces suboptimal results, the boundaries 1010a-d may not be well aligned with the beam spots 1008a-d. The boundaries may be initialized based on a rough estimate, and may be refined through iterative adjustments.

[0128] For example, the area of ​​beam spot 1008a is roughly equal to that of boundary 1010a, but its position is laterally offset and its shape does not match. This results in the sensor elements outside boundary 1010a receiving secondary particles, while the sensor elements inside boundary 1010a do not receive secondary particles. Secondary particles received by sensor elements outside boundary 1010a will not be recorded, while the grouped sensor elements inside the boundary that do not receive secondary particles may only reduce the performance of the detector. On the other hand, the size, shape and position of beam spot 1008b are roughly equal to its boundary 1010b. There may be no sensor elements that should be added to or removed from the group of sensor elements within boundary 1010b. Both beam spots 1008c and 1008d are substantially aligned with their corresponding boundaries 1010c and 1010d. However, the area of ​​beam spot 1008c is smaller than that of boundary 1010c. This results in the following: Fig. 10B As shown, the sensing elements at the bottom of the group are not used. Finally, the beam spot 1008d is larger than the boundary 1010d. Therefore, the group of sensing elements within the boundary 1010d cannot capture every available sensing element, thereby receiving secondary particles, resulting in intensity loss.

[0129] A new boundary 1010 corresponding to the new shape can be determined, and a new group of sensor elements associated with the modified beam spot 1008 can be updated accordingly. However, in comparative embodiments, this requires performing a new picture mode imaging operation, which may result in increased downtime and reduced throughput of the charged particle beam device. It is desirable that the detector be able to automatically update the grouping of sensor elements 1015 in real time. The update can include coupling previously ungrouped sensor elements (addition) or decoupling previously grouped sensor elements (removal). For example, if the secondary particles received by the previously ungrouped sensor elements 1015 are above a first threshold level, indicating that a portion of the beam spot 1008 is incident on the sensor element, the previously ungrouped sensor element 1015 can be added. If the secondary particles received by the previously grouped sensor elements 1015 are below a second threshold level, indicating that a majority of the beam spot 1008 is not incident on the sensor element, the previously grouped sensor elements 1015 can be removed.

[0130] Achieving this high-speed, high-precision capability can present some challenges. One challenge can be the lack of uniquely identifiable intensity readings from individual sensing elements during beam mode operation. This is because sensing elements may be grouped together in the signal readout path, rendering their signals indistinguishable, or completely separated from the signal readout path, potentially making them unreadable. As a result, it can be difficult to determine which sensing elements should be added to or removed from a group when comparing sensing architectures. Another challenge is determining whether the signal of a new sensing element should be associated with a specific beam spot of a specific group. For example, Fig. 10B The sensing element 1015a in the beam is approximately equidistant from each beam spot 1008a-d. Even if it can be determined that the sensing element 1015a is receiving secondary particles above a certain threshold, it still needs to be determined to which sensing element group (if any) it should be assigned.

[0131] Fig.11A is a schematic diagram of a 4x4 portion 1102 of sensing elements 1115 in a detector array 1100 consistent with an embodiment of the present disclosure, which may alleviate some of the issues discussed above. Fig. 11B 1 is a schematic diagram of one such sensor element 1115 in a detector array 1100 consistent with an embodiment of the present disclosure. The detector array 1100 may be, for example, Figure 2-10B Example embodiments of any of the detectors described. Fig.11A The switch matrix design can be used for single beam inspection tools or multi-beam inspection tools (e.g. Figure 2 The switch matrix may include a plurality of transistors as switch elements, as described above with respect to the beam tool 114. Figure 5-Figure 6 Each sensing element 1115 in a switch matrix design may include a threshold circuit 1119 that allows for local actuation of the switching element based on a locally detected parameter.

[0132] Fig.11A In the embodiment, the detector array 1100 may include a plurality of sections (e.g., similar to Figure 3B 1100, including a portion 1102 (enclosed by a dashed box). The portion 1102 may be communicatively coupled to one or more other portions of the detector array 1100. Fig.11A , portion 1102 is communicatively coupled to four adjacent (or neighboring) portions ( Fig.11A In this document, two adjacent objects along a direction may refer to two objects arranged along the direction without an intermediate object therebetween. Such an object may be, for example, part 1102 or sensor element 1115.

[0133] Each sensing element of the detector array 1100 can have substantially the same structure and operate in substantially the same manner. Fig.11A , sensor element circuits 1104 and 1106 (e.g., a unit including a sensor element and associated switching elements and other circuits) are adjacent in a vertical (e.g., y-axis) direction. Portion 1102 also includes an output bus 1108 (shown as a thick black line), which is a shared signal bus for receiving individual detection signals generated by the sensor elements (e.g., at the sensor element circuit 1104 or 1106). Output bus 1108 can output the received signals independently to a portion of the signal path or readout circuit via bus output terminal 1109. Fig.11A As shown, the output bus 1108 can output the signal to the partial circuit 1103. The partial circuit 1103 may include, for example, Figure 3A A switch element 1112 may be arranged between the bus output terminal 1109 and the partial circuit 1103. In some embodiments, when there is no output signal at the bus output terminal 1109, the switch element 1112 may be set to communication disconnection (e.g., open) to reduce parasitic parameters in signal processing.

[0134] Fig. 11B It is consistent with the embodiment of the present disclosure. Fig.11A 1104 of a portion 1102 of a sensor element circuit. The sensor element of the detector array can generate a signal in response to the incidence of an incoming charged particle. Thus, the sensor element can act as a diode in that it can convert the incident energy into a measurable signal and can convert it in a predetermined direction. The sensor element (diode) 1115 can be configured to convert the charged particle landing event into an electrical signal. The sensor element 1115 can be conceptualized as including a diode or other electronic component. As shown in FIG. Fig. 11BAs shown, the sensing element circuit 1104 includes a diode 1115, a grounding switch element 1116, a grounding circuit 1117, an element bus switch element 1118, and inter-element switch elements 1120 and 1122 ( Fig. 11B 1104). For example, in the sensing element circuit 1104, the diode 1115 can convert the energy of the incident charged particles into a measurable electrical signal (e.g., current). For example, the diode 1115 can be a PIN diode, an avalanche diode, an electron multiplier tube (EMT), etc. The grounding switch element 1116 can connect the sensing element circuit 1104 to the grounding circuit 1117. The grounding circuit can be used to release the charge of the unused sensing elements. In some cases, the unused sensing elements can still receive charged particles leaving the chip, such as when the sensing elements are disconnected to reduce crosstalk, noise, or parasitic parameters. If the sensing element is used for charged particle beam detection, the grounding switch element 1116 can keep the communication disconnected (e.g., open). If the sensing element is not used, the grounding switch element can be set to a communication connection (e.g., closed). The element bus switch element 1118 can couple the diode 1115 to the output bus 1108 for communication to output a detection signal. Inter-element switch elements 1120 and 1122 can communicatively couple the sense element circuit 1104 to adjacent sense elements in the horizontal (e.g., x-axis) and vertical (e.g., y-axis) directions, respectively. For example, when the inter-element switch element 1120 is communicatively connected (e.g., closed), the inter-element switch element 1120 can communicatively couple the sense element circuit 1104 to the sense element circuit 1106. Similar components of the sense element circuit 1106 can function in a similar manner to corresponding components of the sense element circuit 1104.

[0135] In some embodiments, the element bus switch elements (e.g., element bus switch element 1118) of the sensor element circuit 1104 can be independently controlled (e.g., respectively by Figure 1 and Figure 2 The controller 109 or the image processing system 290 is controlled by Fig. 9 Controller 904 in the control) to output a signal. More details on the discussion of the sensor element assembly can be found in International Publication No. WO2021 / 239754A1, the entire contents of which are incorporated herein by reference.

[0136] The sensing element circuit 1104 may also include a threshold circuit 1119 configured to actuate a switching element in the sensing element circuit 1104. For example, the threshold circuit 1119 may include one or more transistors configured to transfer charge from the diode 1115 to one of the switching elements (e.g., switching elements 1116, 1118, 1120, or 1122). When a current is generated (or charge is accumulated) at the diode 1115, at least a portion of the current may be transferred to the threshold circuit 1119 to locally determine the current level. The current may be related to the number, rate, or characteristics of secondary particles landing on the sensing surface of the sensing element 1115. The threshold circuit 1119 may include a comparator or other element configured to compare the measured current with a reference value (e.g., one or more thresholds). The threshold circuit 1119 may be further configured to send an actuation signal via a signal line 1121 (shown in dashed lines) to actuate the switching element of the sensing element circuit 1104 based on the measurement or comparison. In some embodiments of the present disclosure, each switching element may be coupled to a dedicated threshold circuit 1119. In some embodiments of the present disclosure, a single threshold circuit 1119 may be coupled to multiple switching elements. In some embodiments of the present disclosure, the switching element and the threshold circuit may be considered as a single element. In this case, the sending of the actuation signal may refer to passing the current directly from the diode 1115 through the threshold circuit 1119 as a switching element and into, for example, a signal readout path of the sensing element group 1115. In some embodiments of the present disclosure, the threshold circuit 1119 may act on the switching element to open or close the switching element, thereby allowing other current from the diode 1115 to pass through the switching element. Sending the actuation signal may refer to driving the switching element through the threshold circuit 1119 so that the switching element passes current from the diode 1115. In this way, the threshold circuit 1119 can act locally, both detecting the parameters of the sensing element and actuating the switching element according to the detected parameters. In some embodiments, one or more of the sensing, threshold setting, comparison, or switch actuation may be controlled or initiated at the sensor level (e.g., by threshold circuit 1119), detector level (e.g., by controller 904), or device level (e.g., by controller 109 or image processing system 290). Threshold circuit 1119 allows determination of the local value of secondary particle landing events at each sensing element 1115. In some embodiments of the present disclosure, even if the sensing element is bounded by other sensing element groups (e.g., Fig. 10A -1010 of Figure B) or when the element is located outside the boundary and isolated from the grouped sensing elements. This determination can also be made during beam mode operation.

[0137] In some embodiments of the present disclosure, the threshold circuit 1119 may be in an idle state unless activated. For example, the threshold circuit may be activated when the associated sensing element of the threshold circuit is a candidate for addition to or removal from the sensing element group. Candidacy may be determined by the proximity of the sensing element to the group boundary. Conditioning activation on such proximity may ensure that changes to the group boundary are gradual and continuous. This may enable the group to accurately track a continuously moving beam spot when real-time information about the beam spot shape is limited. It may also be a fast and efficient way to determine that a sensing element should be associated with a nearby beam spot rather than a more distant beam spot. Proximity may be determined by, for example, locally stored digital information about the switch states of adjacent sensing elements (e.g., stored in the sensing element circuit 1104 or the controller 904). For example, if at least one adjacent sensing element of an ungrouped sensing element is connected to the group by at least one closed switch element, it may be determined that the ungrouped sensing element is a candidate for addition to the group. As another example, if at least one adjacent sensing element in a grouped sensing element is not connected to the group, then the grouped sensing element may be determined to be a candidate to be removed from the group. In this way, the threshold circuit 1119 may be used in conjunction with digital information about the switching states of other elements 1115 in the detector array 1100 to dynamically adjust the beam spot boundaries during beam mode operation, as discussed further below.

[0138] Fig. 11C Shown with Fig.11A -An alternative configuration consistent with the configuration shown in FIG. B. Rather than providing a dedicated threshold circuit 1119 at each sensing element 1115, some embodiments provide a single threshold circuit 1119 that can receive signals from multiple sensing elements. Fig. 11C As shown, a single threshold circuit may serve the entire portion 1102. Alternatively, a single threshold circuit 1119 may serve, for example, two or four sensing elements within a portion, multiple entire portions, or the entire detector. An additional switch matrix (not shown) may be provided to route signals from the sensing element 1115 to the threshold circuit 1119. In this way, a single threshold circuit 1119 may perform threshold processing on multiple sensing elements. For example, the threshold circuit may include a large number of parallel comparator architectures that are configured to perform multiple threshold processing operations simultaneously. In some embodiments of the present disclosure, at any given time, only a portion of the sensing elements will undergo threshold processing operations. Centralizing the threshold circuits 1119 can advantageously reduce the total number of threshold components required in the detector. The threshold circuits 1119 may form, for example, Figure 1 and Figure 2 The controller 109 or the image processing system 290, Fig. 9 Part of the controller 904 or another part of the detector processing circuit system.

[0139] Fig. 12A - Figure D shows an example of a dynamic beam spot boundary adjustment process on a portion of a detector 1200 consistent with an embodiment of the present disclosure. The detector 1200 may be, for example Figure 2-11B The sensing element 1215 of the detector 1200 may include Fig.11A - Circuit elements described in FIG. B. For example, in some embodiments of the present disclosure, the sensing element 1215 may include a diode 1115, a switch element 1116 / 1118 / 1120 / 1122 connected to the diode, a threshold circuit 1119 connected to the diode, and a signal line 1121 connected to the switch element.

[0140] exist Fig. 12A In FIG. 1 , beam spot 1208 overlaps with its designated set of sensing elements within boundary 1210, but is mismatched. The mismatch may be similar to Fig. 10B The mismatch between the beam spot 1008a and the boundary 1010a is shown in FIG. The beam spot 1208 may be one of an array of beam spots formed on the surface of the detector 1200 during beam mode operation. During beam mode operation, the boundary 1210 may be updated periodically or continuously by dynamic beam spot boundary adjustment.

[0141] Initially, a sensor element 1215 is determined to be a candidate for update. Here, the update may include adding a candidate to a sensor element group (e.g., within boundary 1210) (e.g., 1215a / d) or removing a candidate from a sensor element group (e.g., 1215b / c). In some embodiments of the present disclosure, multiple such candidates may be identified substantially simultaneously (e.g., within the same clock cycle of a processor, or within a few clock cycles, such as 10 or 100 cycles), and multiple update processes may be performed substantially in parallel. Candidate eligibility may be determined by determining the proximity of the candidate sensor element 1215 to the group boundary 1210. This may be accomplished using digital information about the switch state of the element or other grouping information. For example, there may be accessible digital information showing that sensor element 1215b is grouped within boundary 1210, in part because one or more of its inter-element switch elements or element bus switch elements (not shown) are closed to connect sensor element 1215b to the group. Additionally, there may be accessible digital information indicating that neighboring sensor element 1215a is not grouped within boundary 1210, in part because its switch element may be open. Since the grouped sensor element is directly adjacent to the ungrouped sensor element, both are determined to be near boundary 1210 and identified as candidates 1215. The same is true for sensor elements 1215c-d. Grouping information may take other forms. But relying on switch states may be one way to allow detector 1200 to quickly process information about the states of neighboring sensor elements.

[0142] like Fig. 12A As shown, proximity may refer to two sensor elements being directly adjacent to each other, such as sensor elements 1215a-b. However, in some embodiments of the present disclosure, proximity may refer to two sensor elements being within a specified number of sensor elements, or any other suitable proximity measure. For example, proximity may be determined based on the location of the sensor elements within a defined area of ​​the detector surface. When non-adjacent sensor elements are identified as candidates, subsequent adding or removing steps may or may not include adding or removing any intervening sensor elements. Furthermore, even if Fig.11A The switch matrix shown is not configured with diagonal inter-element switch elements, and diagonally adjacent sensing elements may also be considered adjacent. In some embodiments of the present disclosure, sensing elements are considered adjacent only when they share common inter-element switch elements. In some embodiments of the present disclosure, diagonal inter-element switch elements may exist in the switch matrix.

[0143] In some embodiments, candidacy may not be determined by proximity at all, but by another suitable grouping parameter. For example, a sensing element may be considered a candidate for addition / removal by reference to a beam spot shape model, historical information on the progression of the beam spot shape, etc. In some embodiments of the present disclosure, the determination of candidacy may be eliminated entirely or performed in another order. For example, instead of activating a threshold circuit (e.g., 1119) based on some candidacy parameter, a sensing element may continuously monitor its current through a threshold circuit and determine the addition or removal action only after a threshold level is exceeded. In this case, adding a sensing element may include deciding to which group the sensing element should be added.

[0144] exist Fig. 12A , a plurality of exemplary sensing elements 1215a-e are shown. According to the process discussed below (and shown by the overlap of beam spots 1208): sensing element 1215a is an example of an ungrouped sensing element that will be added to a group; sensing element 1215b is an example of a grouped sensing element that will remain in a group; sensing element 1215c is an example of a grouped sensing element that will be removed from a group; and sensing element 1215d is an example of an ungrouped sensing element that will remain outside a group. Although there is some beam spot overlap, sensor element 1215e is not currently Fig. 12A However, if the adjacent sensing element 1215a is grouped, then the sensing element 1215e may become a candidate and be added to the group in a subsequent update cycle.

[0145] Fig. 12B It is shown that the embodiment of the present disclosure is consistent with Fig. 12AIn the example embodiment of the detector 1200, each sensor element that can be identified as a candidate is identified. In this embodiment, each sensor element that is adjacent to the boundary 1210 horizontally or vertically (i.e., not diagonally due to the lack of diagonal switching elements in this example embodiment) is identified as a candidate. The sensor elements marked with an "X" in the figure are grouped sensor elements that are identified as candidates for removal from the group. The sensor elements marked with an "O" in the figure are ungrouped sensor elements that are identified as candidates for addition to the group. Note that in Fig. 12B In some embodiments of the present disclosure, each candidate to be added to the group is adjacent to a candidate to be removed from the group, and vice versa. In some embodiments of the present disclosure, the candidates of a sensing element can be determined when adjacent sensing elements have different grouping states. For example, if one of the adjacent sensing elements of the sensing element is already a member of the group, the sensing element may be a candidate to be added to the group. If one of the adjacent sensing elements of the sensing element is not a member of the group, the sensing element may be a candidate to be removed from the group. Each candidate sensing element can be coupled to a threshold circuit (not shown) that is activated to measure the current generated at the sensing element from the beam spot 1208. The threshold circuit can be configured to compare the measurement result with a certain threshold.

[0146] If the sensing element receives a large number of secondary particles from the beam spot 1208, an ungrouped sensing element O may be added. Thus, the current measured at the ungrouped sensing element O may be compared to a first threshold, and if the sensing element O exceeds the first threshold, it may be added to the group of sensing elements within the boundary 1210. If the sensing element does not receive enough secondary particles from the beam spot 1208 to justify its presence in the group, the grouped sensing element X may be removed. Thus, the current measured at the grouped sensing element X may be compared to a second threshold, and if the sensing element X is below the second threshold, it may be removed from the group. In some embodiments of the present disclosure, the first threshold and the second threshold may be the same. In some embodiments of the present disclosure, the first threshold and the second threshold may be different. For example, the first threshold may be higher than the second threshold. In some embodiments of the present disclosure, non-adjacent sensing elements may be candidates, and a third threshold may be set for additional candidate elements that are farther from the boundary 1210. For example, ungrouped candidate sense elements that are displaced, for example, by three sense elements relative to the boundary 1210 may be compared to a third threshold that is higher than the first threshold and may be added only if the current from the more distant sense elements exceeds the higher threshold.

[0147] Fig. 12C Some embodiments of the present disclosure are shown Fig. 12A-Exemplary embodiment of FIG. B. Here, the sensing elements labeled "A" are candidates for addition to the group. This may be because the threshold circuit at each sensing element A receives a current exceeding a first threshold. Therefore, one or more switch elements previously opened in each sensing element A may be closed to pass current from the sensing element to the signal readout path of the group. In addition, the grounding switch element (e.g. Fig. 11B 1116) can be opened by a threshold circuit or another control signal (e.g., controller 904).

[0148] The sensing elements marked as "D" are candidates for removal from the group. This may be because the threshold circuit at each sensing element receives a current below the second threshold, or receives no current. Therefore, any switch element in sensing element D that was previously closed to connect sensing element D to the signal readout path of the group may be opened to decouple the parasitic parameters of sensing element D from the group. Additionally, a grounding switch element (e.g. Fig. 11B 1116 in the figure) can be closed by a threshold circuit or another control signal (e.g., controller 904). The switch state of each of these elements can be updated accordingly so that new digital information about the new state of the switch element can be obtained.

[0149] at last, Fig.12D An updated boundary 1210 of the element group is shown. The updated boundary 1210 more closely follows the shape and location of the beam spot 1208. The result is a group of sensing elements that maximizes the capture of secondary particles of the beam spot 1208 while minimizing parasitic parameters of unused sensing elements.

[0150] Fig.12D Also shown is what may happen to some sensor elements when the updated boundary 1210 moves toward or away from the sensor element. For example, as described above, sensor element 1215e may be moved to the edge of the sensor element 1215e. Fig. 12A - In Figure B, secondary particles are received but are not identified as candidates and therefore not thresholded or added to the group. Fig.12D , sensor element 1215e is now adjacent to updated boundary 1210 via newly grouped sensor element 1215a. Thus, sensor element 1215e can be identified as a candidate and subsequently added to the group in a second cycle of the update process. Because the threshold circuit can automatically sense the current and actuate the switch element based on the analog signal, the update process can occur in a fast cycle with minimal action required by the centralized signal processing circuitry. Thus, even a multi-step update process, such as the sequential addition of sensor elements 1215a and 1215e in the figure, can be identified as a candidate during the update process. Fig. 12AAs shown in FIG. D , this change can occur at a sufficient speed so that the change in the charged particle beam spot 1208 on the detector 1200 can be easily tracked.

[0151] As another example, Fig.12D 1215d. FIG. 1216 illustrates how the threshold operation within the sensing element ends without any change in the switch state of the sensing element. The previously grouped sensing element 1215c has been removed from the group, which changes the proximity state of sensing element 1215d. Since sensing element 1215d is no longer adjacent to the group boundary 1210, it may no longer be identified as a candidate in this exemplary embodiment. Based on the new switch state information of sensing element 1215c, a controller (e.g., Fig. 9 Controller 904, Figure 1 The controller 109 or Figure 2 The image processing system 290 may terminate the threshold operation at the sensing element 1215d. The sensing element 1215d may then return to a normal off state.

[0152] Fig.12E and Figure F shows Fig. 12A - How the process in Figure D changes the parameters that determine the optimal configuration of signal routing paths in a switch matrix. Fig.12E and Figure F show Fig. 12C The boundary 1210 of the sensor element group at the time shown in Figure D. For clarity, the beam spot 1208 is omitted. As shown by the light and dark areas, the sensor elements can be functionally divided into, for example, parts of a 4x4 array, such as Figure 4 Section 321 of Figure 4 As discussed above, there are many ways to configure the signal readout path in the detector 1200. For example, when the boundary 1210 around the sensing element group is Fig.12E The configuration changes to Fig.12F When the configuration of , section 1221 begins to contribute a single sensor element to the group, whereas it did not contribute any sensor element before. For example, the single sensor element can be added by closing an inter-element switch element that connects the single sensor element to the adjacent sensor element in the center section 1223.

[0153] However, the change in section 1222 is more dramatic. Section 1222 changes from Fig.12E The original seven sensor elements become Fig.12F In the initial configuration, for example, portion 1222 may be coupled to portion 1223 via an interconnect switch element in an interconnect layer, where each of the seven sensor elements is coupled to the interconnect layer via its own element bus switch element. In some embodiments, when the change is Fig.12FWhen configured as described above, each sensing element can perform independent threshold operations within its own threshold circuit and function independently of the other threshold circuits of other sensing elements. This may result in each of the threshold circuits of the four discarded sensing elements of portion 1222 removing its respective sensing element by opening the corresponding element bus switch element. However, the resulting arrangement may not produce the optimal switch configuration in terms of parasitic parameters. It may be more advantageous, for example, to disconnect the entire analog signal path of portion 1222 and couple the remaining three sensing elements to portion 1223 via its inter-element switch elements.

[0154] In some embodiments of the present disclosure, the controller may be configured to determine the optimal switch configuration simultaneously with the threshold operation, so that FIG. 12E to FIG. 12F The controller can select the best switch configuration in real time during the transition period. For example, the controller can determine a set of configurations that can be implemented for a given candidate that meets its respective threshold from a set of candidates currently undergoing threshold operation. For this purpose, a set of configuration templates can be stored in, for example, a lookup table.

[0155] In some embodiments of the present disclosure, switching can be performed in multiple stages. In the first stage, the threshold operation can actuate the switch to immediately add or remove the sensing element from the group. For example, the threshold circuit can actuate the element bus switch element in section 1222 to remove four sensing elements from the group, and actuate the inter-element switch element to add a single sensing element from section 1221. In the second stage, the controller (e.g., Figure 1 and Figure 2 The controller 109 or the image processing system 290, or Fig. 9 The controller 904 in the embodiment may determine whether the switch configuration completed during the one or more switching operations described above results in an optimal configuration. This determination may be performed periodically, each time the switch matrix is ​​actuated, or after a specified number of switches have been performed, etc. If the controller determines that a better switch matrix configuration exists, the controller may actuate the appropriate switches to achieve the better configuration.

[0156] Fig.13 A flow chart of an exemplary method for dynamically updating switch elements in a detector switch matrix consistent with an embodiment of the present disclosure is shown. The detector may be, for example, Figure 2-12D Any of the charged particle detectors disclosed herein. The detector may be such as Figure 1-Figure 2 The detector may include a plurality of individual sensing elements arranged on a surface of the detector. Each sensing element may include a plurality of switching elements for selectively coupling and decoupling the sensing elements to each other and to other circuitry and wiring paths in the detector. The plurality of switching elements may include a switch matrix of the detector.

[0157] In step S1301, a charged particle beam process begins. The charged particle beam process can be, for example, a SEM inspection process. Specifically, the process can be a beam mode operation, in which a primary electron beam irradiates a sample surface to produce a corresponding secondary beam, which produces a beam spot on an area of ​​a detector surface. The area may include a plurality of sensor elements. In some embodiments, there may be an array of primary electron beams, which irradiate a sample surface to produce a corresponding array of secondary beams, which produce an array of beam spots on different areas of the detector surface. A group of sensor elements may be selected to correspond to the beam spot based on, for example, a previous picture mode imaging operation. For example, a group of continuous sensor elements may be selected, which corresponds to the shape, size and position of the beam spot on the detector, which shape, size and position are determined by a high-resolution picture mode image of the beam spot. The beam spot may overlap with the group of sensor elements, but cannot coexist with it. The sensor elements in the selected group may be operatively coupled to each other by closing a plurality of switch elements in a switch matrix. In this way, by illuminating a beam spot into a group, the signal generated at each sensing element in the group can be directed to a common signal readout path of the detector to produce a common measurement of the beam spot (eg, an intensity measurement).

[0158] In step S1302, the sensor element is identified as a candidate for updating the group by dynamic switching during charged particle beam processing. Candidates can be selected so that they are added to the group or removed from the group. For example, if the beam spot irradiates an ungrouped sensor element, the ungrouped sensor element can be added to the group. If the grouped sensor element is not irradiated by the beam spot, it can be removed from the group. Both situations are more likely to occur at sensor elements close to the group boundary. Therefore, if the sensor element is close to the boundary of the group selected for the beam spot, it can be considered as a candidate. For example, if the sensor element is adjacent to the boundary of the group, it can be considered as a candidate. Neighboring sensor elements outside the boundary can be candidates for addition to the group, while neighboring sensor elements inside the boundary can be candidates for removal from the group. In other words, when neighboring elements have different grouping states, the sensor element can be a candidate for update. For example, if one of the neighboring sensor elements of a certain sensor element is already a member of the group, the sensor element can be a candidate for addition to the group. If one of a sensor element's neighbors is not a member of the group, the sensor element may be a candidate for removal from the group.

[0159] The detector control circuitry may continuously identify multiple candidate sensing elements simultaneously, and once the threshold operation is initiated as described below, each candidate sensing element may semi-automatically perform the remaining steps in parallel. This may continue until, for example, the charged particle beam process is complete. Alternatively, candidate sensing elements may be identified at predetermined repeating intervals. Candidate sensing elements may also be identified at irregular intervals, for example when the determination of the beam spot boundaries may need to be updated based on other performance parameters.

[0160] In step S1303, the threshold circuit in the candidate sensing element performs a threshold operation. The threshold operation may be performed by a control circuit (such as Fig. 9 Controller 904, Figure 1 The controller 109 or Figure 2 The image processing system 290 of FIG. 290 is initiated based on the determination that the sensing element is a candidate. At least a portion of the current (if any) generated at the diode of the sensing element may be transferred as a signal to a threshold circuit of the sensing element and measured or compared to a threshold. For example, a comparator of the threshold circuit may compare the signal to a selected threshold. The threshold may vary depending on whether the sensing element is a candidate for addition or removal. For example, if the sensing element is a candidate for addition to the group, the threshold circuit may compare the signal to a first threshold. If the sensing element is a candidate for removal from the group, the threshold circuit may compare the signal to a second threshold. The second threshold may be equal to or lower than the first threshold.

[0161] At step S1304, if the threshold comparison is not satisfied, the threshold circuit does not actuate any switch element within the candidate sensing element. The method proceeds to step S1305. If the sensing element is still a candidate, the threshold operation proceeds to step S1306. This loop may continue until the threshold is satisfied or the sensing element is no longer a candidate. If the sensing element is no longer a candidate (e.g., due to Fig.12D If the threshold operation is not initiated due to the boundary shift shown, or due to the end of the charged particle beam process), the threshold operation ends at step S1307. Therefore, in some embodiments of the present disclosure, the threshold operation, once initiated, can remain active until the sensing element is no longer a candidate or the threshold is met.

[0162] At step S1304, if the threshold is met, the method proceeds to step S1308. For example, if the signal from the diode to the threshold circuit exceeds a first threshold, adding a candidate may proceed to step S1308. If the signal from the diode to the threshold circuit is below a second threshold, removing a candidate may proceed to step S1308.

[0163] In step S1308, the switch element is actuated so that the sensing element is added to (or removed from) the group. For example, the candidate to be added can be added to the group. In this case, for example, the switch element can be closed to transfer the charge from the added sensing element to the group. The switch element can be, for example, an inter-element switch element between the added sensing element and the adjacent element that already belongs to the group. The specific switch to be actuated can be selected by the control signal provided, for example, during the initiation of the threshold operation. The added sensing element then becomes part of the group, and there is a new boundary around the sensing element group. In some embodiments, the added sensing element may immediately become a candidate to be removed because it has become the outermost sensing element in the group. In some embodiments, a time delay or other buffering signal can be applied to prevent it from becoming a candidate immediately, thereby preventing the sensing element from repeatedly flickering due to the threshold operation. In some embodiments, this flicker can be avoided by setting a sufficiently large difference between the first and second thresholds. In some embodiments, this flicker can be simply tolerated or not considered a problem.

[0164] If in step S1308, the sensor element is a candidate for removal that is removed from the group, the threshold circuit may actuate the selected switching element to prevent any additional charge from being transferred from the removed sensor element to the group. The removed sensor element may be completely disconnected from the group to minimize the impact of the parasitic parameters of the removed sensor element on the group. The removed sensor element is then no longer part of the group, and a new boundary exists around the remaining group of sensor elements. In some embodiments, the removed sensor element may immediately become a candidate for addition because it has become an ungrouped sensor element adjacent to the new boundary. The same flicker considerations discussed above with respect to the addition scenario may equally apply to the removal scenario.

[0165] After step S1308, the process for the particular sensor element ends. However, as described above, in some embodiments of the present disclosure, the process may occur continuously on all candidate sensor elements, so that the sensor element group may be continuously updated during the charged particle beam process.

[0166] A non-transitory computer-readable medium may be provided, the medium storing the above-mentioned Fig.13 An exemplary flow chart for detecting a controller of a charged particle beam (e.g., Figure 1 The controller 109 or Fig. 9The instructions stored in the non-transitory computer readable medium may be executed by the circuit system of the controller to perform the method 1300 in part or in whole. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tapes or any other magnetic data storage media, compact disk read-only memories (CD-ROMs), any other optical data storage media, any physical media with a pattern of holes, random access memories (RAMs), programmable read-only memories (PROMs) and erasable programmable read-only memories (EPROMs), FLASH-EPROMs or any other flash memory, non-volatile random access memories (NVRAMs), caches, registers, any other memory chips or cartridges, and networked versions thereof.

[0167] Embodiments of the present disclosure may also be described by the following terms:

[0168] 1. A charged particle detector, comprising:

[0169] substrate;

[0170] a plurality of switch elements formed on the substrate and configured to form a switch matrix, the switch matrix having a plurality of inputs, each input configured to be connected to a different one of a plurality of sensor elements, each of the sensor elements configured to generate a signal in response to a charged particle impinging on the sensor element, the switch matrix configured to combine a group of signals generated from a group of the sensor elements associated with a charged particle beam spot formed on the charged particle detector; and

[0171] a plurality of threshold circuits, each of the threshold circuits being coupled to a different one of the plurality of sensing elements,

[0172] wherein a first threshold circuit of the plurality of threshold circuits is coupled to a first sensing element of the plurality of sensing elements and is configured to actuate a first switching element of the switch matrix based on a comparison of a signal level of the first sensing element with a threshold value;

[0173] wherein the first sensor element is configured to be identified as a candidate for one of: being added to the sensor element group or being removed from the sensor element group based on the proximity of the first sensor element to a boundary of the sensor element group; and

[0174] The first threshold circuit is configured to initiate the comparison in response to the first sensing element being identified as a candidate.

[0175] 2. A charged particle detector according to clause 1, wherein the first threshold circuit is configured to close the first switching element in response to the signal level of the first sensing element exceeding the threshold value so that the first switching element conducts current.

[0176] 3. A charged particle detector according to claim 2, wherein the first sensor element is added to the sensor element group by closing the first switch element by the first threshold circuit so that the signal from the first sensor element is combined with the signal group generated from the sensor element group.

[0177] 4. A charged particle detector according to clause 3,

[0178] wherein the threshold is a first threshold, and

[0179] The first threshold circuit is configured to open the first switching element to prevent the first switching element from conducting current in response to the signal level of the first sensing element falling below a second threshold, wherein the second threshold is lower than the first threshold.

[0180] 5. A charged particle detector according to claim 4, wherein the first sensing element is removed from the sensing element group by opening the first switching element by the first threshold circuit to prevent the signal from the first sensing element from combining with the signal group generated from the sensing element group.

[0181] 6. The charged particle detector of claim 1, wherein the first threshold circuit is configured to open the first switching element in response to the signal level of the first sensing element falling below the threshold to prevent the first switching element from conducting current.

[0182] 7. A charged particle detector according to claim 6, wherein the first sensing element is removed from the sensing element group by opening the first switching element by the first threshold circuit to prevent the signal from the first sensing element from combining with the signal group generated from the sensing element group.

[0183] 8. A charged particle detector according to clause 7,

[0184] wherein the threshold is a second threshold, and

[0185] The first threshold circuit is configured to close the first switch element in response to the signal level of the first sensing element exceeding a first threshold value so that the first switch element conducts current, wherein the first threshold value is higher than the second threshold value.

[0186] 9. A charged particle detector according to claim 8, wherein the first sensor element is added to the sensor element group by closing the first switch element by the first threshold circuit so that the signal from the first sensor element is combined with the signal group generated from the sensor element group.

[0187] 10. A charged particle detector according to clause 1, wherein the sensing element comprises a diode.

[0188] 11. A charged particle detector according to clause 1, wherein the threshold comprises a threshold charge or current.

[0189] 12. The charged particle detector according to clause 1, further comprising:

[0190] a second sensing element adjacent to the first sensing element;

[0191] The proximity of the first sensor element to the boundary of the sensor element group is determined based on the first sensor element having a different grouping state from the second sensor element.

[0192] 13. A charged particle detector according to clause 12, wherein:

[0193] The first sensor element is in a state of being grouped together with the sensor element group;

[0194] The second sensor element is in a state of not being grouped together with the sensor element group;

[0195] The first sensor element is a candidate for removal from the set of sensor elements; and

[0196] The second sensor element is a candidate for being added to the sensor element group.

[0197] 14. A charged particle detector according to clause 13, wherein the first threshold circuit is configured to remove the first sensing element from the sensing element group by opening the first switching element in response to the first signal level being lower than the threshold.

[0198] 15. A charged particle detector according to clause 14, wherein:

[0199] In response to being removed from the sensing element group by the first threshold circuit, the first sensing element is configured to be identified as a candidate for addition to the sensing element group; and

[0200] The first threshold circuit is configured to initiate a second comparison of the signal level of the first sensor element with a second threshold in response to the first sensor element being identified as the candidate for addition to the set of sensor elements.

[0201] 16. A charged particle detector according to clause 12, wherein:

[0202] The first sensor element is in a state of not being grouped together with the sensor element group;

[0203] The second sensor element is in a state of being grouped together with the sensor element group;

[0204] The first sensor element is a candidate for being added to the sensor element group; and

[0205] The second sensor element is a candidate for being removed from the sensor element group.

[0206] 17. A charged particle detector according to clause 16, wherein the first threshold circuit is configured to add the first sensing element to the sensing element group by closing the first switching element in response to the first signal level exceeding the threshold.

[0207] 18. A charged particle detector according to clause 17, wherein the second sensing element is coupled to the first sensing element via the first switching element.

[0208] 19. A charged particle detector according to clause 17, wherein:

[0209] In response to being added to the sensing element group by the first threshold circuit, the first sensing element is configured to be identified as a candidate for removal from the sensing element group; and

[0210] The first threshold circuit is configured to initiate a second comparison of the signal level of the first sensor element with a second threshold in response to the first sensor element being identified as a candidate for removal from the set of sensor elements.

[0211] 20. The charged particle detector of clause 1, wherein the substrate comprises the plurality of transistors.

[0212] 21. A method for updating a set of sensor elements in a charged particle detector, the method comprising:

[0213] irradiating a sample to produce a secondary beam spot on the charged particle detector, the secondary beam spot overlapping the sensor element group;

[0214] identifying the first sensor element as a candidate for updating the grouping state of the first sensor element based on the proximity of the first sensor element to a boundary of the sensor element group;

[0215] initiating a threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector;

[0216] wherein the threshold operation comprises comparing the signal level of the first sensing element with a threshold value; and

[0217] According to the comparison result, the first switch element is actuated to update the grouping state of the sensor elements.

[0218] 22. A method according to clause 21, wherein identifying the first sensor element as a candidate for updating the grouping state of the first sensor element based on the proximity of the first sensor element to the boundary of the sensor element group includes: determining whether a neighboring sensor element adjacent to the first sensor element has a grouping state different from that of the first sensor element.

[0219] 23. The method of clause 22, wherein the first sensor element is a grouped sensor element and the adjacent sensor element is an ungrouped sensor element.

[0220] 24. The method of clause 22, wherein the first sensor element is an ungrouped sensor element and the adjacent sensor element is a grouped sensor element.

[0221] 25. A method according to clause 21, wherein:

[0222] The comparing includes determining whether the signal level of the first sensing element exceeds the threshold;

[0223] Actuating the first switching element includes closing the first switching element so that the first switching element conducts current; and

[0224] Updating the grouping state of the first sensor element includes: adding the first sensor element to the sensor element group.

[0225] 26. A method according to clause 25,

[0226] wherein the threshold is a first threshold,

[0227] The method further includes determining that the signal level of the first sensing element is below a second threshold;

[0228] opening the first switching element to prevent the first switching element from conducting current; and

[0229] The grouping state of the first sensor element is updated to remove the first sensor element from the sensor element group.

[0230] 27. The method according to clause 25, further comprising:

[0231] After the first sensor element is added to the sensor element group, identifying a second sensor element as a candidate for updating the grouping state of the second sensor element;

[0232] The second sensing element is adjacent to the first sensing element.

[0233] 28. The method according to clause 27, further comprising:

[0234] initiating an additional threshold operation of the second sensing element by a second threshold circuit coupled to the second sensing element and a second switching element of a switching matrix of the detector;

[0235] wherein the further threshold operation comprises comparing the signal level of the second sensing element with a further threshold; and

[0236] Depending on the comparison with the further threshold value, the second switch element is actuated to update the grouping state of the sensor elements.

[0237] 29. A method according to clause 21, wherein:

[0238] The comparing includes determining whether the signal level of the first sensing element is below the threshold;

[0239] actuating the first switching element comprises opening the first switching element to prevent the first switching element from conducting current; and

[0240] Updating the grouping status of the first sensor element includes removing the first sensor element from the sensor element group.

[0241] 30. A method according to clause 29,

[0242] wherein the threshold is a second threshold,

[0243] The method further includes determining that the signal level of the first sensing element exceeds a first threshold;

[0244] closing the first switching element so that the first switching element conducts current; and

[0245] The grouping state of the first sensor element is updated to add the first sensor element to the sensor element group.

[0246] 31. The method according to clause 29, further comprising:

[0247] After the first sensor element is removed from the sensor element group, a candidate state of a second sensor element that is adjacent to the first sensor element and is not adjacent to a boundary of the sensor element group is terminated.

[0248] 32. The method of clause 21, wherein the threshold operation continues until the threshold is met or the threshold operation is terminated by a controller of the charged particle detector.

[0249] 33. The method of clause 21, wherein the proximity of the first sensor element to a boundary of the group of sensor elements comprises the first sensor element being adjacent to a boundary of the group of sensor elements.

[0250] 34. The method of clause 21, wherein in response to the first sensor element being adjacent to a boundary of the sensor element group, the first sensor element is identified as a candidate for updating the grouping state of the first sensor element.

[0251] 35. A non-transitory computer readable medium according to clause 35 storing a set of instructions executable by at least one processor of a device to cause the device to perform a method of updating a sensor element group based on a beam spot exposed to a charged particle detector, the method comprising:

[0252] identifying the first sensor element as a candidate for updating the grouping state of the first sensor element based on the proximity of the first sensor element to a boundary of the sensor element group;

[0253] initiating a threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switching matrix of the detector;

[0254] wherein the threshold operation comprises comparing the signal level of the first sensing element with a threshold value; and

[0255] Based on the comparison result, the first switch element is actuated to update the grouping status of the sensor elements.

[0256] 36. A non-transitory computer-readable medium according to clause 35, wherein identifying the first sensor element as a candidate for updating the grouping state of the first sensor element based on the proximity of the first sensor element to the boundary of the sensor element group includes: determining whether an adjacent sensor element adjacent to the first sensor element has a grouping state different from that of the first sensor element.

[0257] 37. The non-transitory computer-readable medium of clause 36, wherein the first sensor element is a grouped sensor element and the adjacent sensor element is an ungrouped sensor element.

[0258] 38. The non-transitory computer readable medium of clause 36, wherein the first sensor element is an ungrouped sensor element and the adjacent sensor element is a grouped sensor element.

[0259] 39. The non-transitory computer-readable medium of clause 35, wherein:

[0260] The comparing includes determining whether the signal level of the first sensing element exceeds a threshold;

[0261] Actuating the first switching element includes closing the first switching element so that the first switching element conducts current; and

[0262] Updating the grouping status of the first sensor element includes adding the first sensor element to the sensor element group.

[0263] 40. The non-transitory computer readable medium of clause 39,

[0264] wherein the threshold is a first threshold,

[0265] The set of instructions is executable by at least one processor of the device, which is configured to cause the device to further perform:

[0266] determining that the signal level of the first sensing element is below a second threshold;

[0267] opening the first switching element to prevent the first switching element from conducting current; and

[0268] The grouping state of the first sensor element is updated to remove the first sensor element from the sensor element group.

[0269] 41. The non-transitory computer-readable medium of clause 39, wherein the set of instructions executable by at least one processor of a device causes the device to further perform:

[0270] After the first sensor element is added to the sensor element group, a second sensor element is identified as a candidate for updating a grouping state of the second sensor element, the second sensor element being adjacent to the first sensor element.

[0271] 42. The non-transitory computer-readable medium of clause 41, wherein the set of instructions executable by at least one processor of a device causes the device to further perform:

[0272] initiating an additional threshold operation of the second sensing element by a second threshold circuit coupled to the second sensing element and a second switching element of the switching matrix of the detector;

[0273] wherein the further threshold operation comprises comparing the signal level of the second sensing element with a further threshold; and

[0274] Depending on the comparison with the further threshold value, the second switch element is actuated to update the grouping state of the sensor elements.

[0275] 43. The non-transitory computer-readable medium of clause 35, wherein:

[0276] The comparing includes determining whether the signal level of the first sensing element is below the threshold;

[0277] actuating the first switching element comprises opening the first switching element to prevent the first switching element from conducting current; and

[0278] Updating the grouping status of the first sensor element includes removing the first sensor element from the sensor element group.

[0279] 44. The non-transitory computer readable medium of clause 43,

[0280] wherein the threshold is a second threshold,

[0281] The set of instructions is executable by at least one processor of the device, which is configured to cause the device to further perform:

[0282] determining that the signal level of the first sensing element exceeds a first threshold;

[0283] closing the first switching element so that the first switching element conducts current; and

[0284] The grouping state of the first sensor element is updated to add the first sensor element to the sensor element group.

[0285] 45. The non-transitory computer-readable medium of clause 43, wherein the set of instructions executable by at least one processor of a device causes the device to further perform:

[0286] When the first sensor element is removed from the sensor element group, the candidate state of the second sensor element is terminated, the second sensor element is adjacent to the first sensor element and is not adjacent to a boundary of the sensor element group.

[0287] 46. ​​The non-transitory computer readable medium of clause 35, wherein the proximity of the first sensor element to a boundary of the group of sensor elements comprises the first sensor element being adjacent to a boundary of the group of sensor elements.

[0288] 47. The non-transitory computer-readable medium of clause 35, wherein the threshold operation continues until one of the thresholds is met or the threshold operation is terminated by a controller of the detector.

[0289] 48. The non-transitory computer-readable medium of clause 35, wherein the first sensing element comprises a PIN diode.

[0290] 49. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a device to cause the device to perform a method comprising:

[0291] operatively coupled to a set of sensing elements in a charged particle detector;

[0292] The set of sensor elements is updated by one of the following:

[0293] adding the candidate sensor element to the group by operatively coupling the candidate sensor element to the group, or

[0294] removing the candidate sensing element from the group by operatively decoupling the candidate sensing element from the group;

[0295] Wherein the updating occurs during a charged particle exposure operation on the charged particle detector.

[0296] 50. A method comprising:

[0297] operatively coupled to a set of sensing elements in a charged particle detector;

[0298] Update the group of sensing elements in one of the following ways:

[0299] adding the candidate sensor element to the group by operatively coupling the candidate sensor element to the group, or

[0300] removing the candidate sensing element from the group by operatively decoupling the candidate sensing element from the group;

[0301] Wherein the updating occurs during a charged particle exposure operation on the charged particle detector.

[0302] 51. A system comprising:

[0303] a charged particle detector comprising a plurality of sensing elements;

[0304] A controller having circuitry configured to:

[0305] operatively coupling a group of sensing elements of the plurality of sensing elements;

[0306] The set of sensing elements is updated during charged particle exposure on the charged particle detector by one of the following means:

[0307] adding the candidate sensor element to the group by operatively coupling the candidate sensor element to the group, or

[0308] The candidate sensing element is removed from the grouping by operatively decoupling the candidate sensing element from the grouping.

[0309] 52. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a device to cause the device to perform a method comprising:

[0310] operatively coupled to a set of sensing elements in a charged particle detector;

[0311] The first sensor element is identified as a candidate for updating the group of sensor elements by one of the following means:

[0312] adding the first sensor element to the group by operatively coupling a candidate sensor element to the group, or

[0313] removing the first sensing element from the group by operatively decoupling the candidate sensing element from the group;

[0314] Wherein identifying the first sensor element as a candidate is based on proximity of the first sensor element to a second sensor element that is part of a group of the sensor elements.

[0315] 53. A method comprising:

[0316] operatively coupled to a set of sensing elements in a charged particle detector;

[0317] The first sensor element is identified as a candidate for updating the group of sensor elements by one of the following means:

[0318] adding the first sensor element to the group by operatively coupling a candidate sensor element to the group, or

[0319] removing the first sensing element from the group by operatively decoupling the candidate sensing element from the group;

[0320] Therein, identifying the first sensor element as a candidate is based on proximity of the first sensor element to a second sensor element that is part of a group of the sensor elements.

[0321] 54. A system comprising:

[0322] a charged particle detector including a plurality of sensing elements;

[0323] A controller having circuitry configured to:

[0324] a component group operatively coupled to a sensing element of the plurality of sensing elements;

[0325] The first sensor element is identified as a candidate for updating the group of sensor elements by one of the following means:

[0326] adding a first sensor element to the group by operatively coupling a candidate sensor element to the group, or

[0327] removing the first sensing element from the group by operatively decoupling the candidate sensing element from the group;

[0328] Wherein identifying the first sensor element as a candidate is based on proximity of the first sensor element to a second sensor element that is part of a group of the sensor elements.

[0329] 55. A method of reducing noise in an electron detector of a multi-beam scanning electron microscope (SEM), comprising:

[0330] receiving, by a sensing element of the electron detector, electrons from a plurality of secondary electron beams emitted by a sample in response to a plurality of primary beams of the multi-beam SEM interacting with the sample, each of the secondary beams being associated with a different one of the plurality of primary beams;

[0331] coupling a first set of sensing elements of the electron detector corresponding to a first beam spot of one of the secondary electron beams based on the received electrons; and

[0332] Adjusting the first group of sensing elements comprises:

[0333] coupling the first sensing element to the first group in response to a first detected charge at the first sensing element exceeding a first threshold, wherein coupling the first sensing element to the first group enables charge to be transferred from the first sensing element to a signal readout path of the first group; or

[0334] Decoupling the second sensing element from the first group in response to a second detected charge at the second sensing element being below a second threshold, wherein decoupling the second sensing element from the first group prevents charge from being transferred from the second sensing element to the signal readout path of the first group.

[0335] 56. A method according to clause 55, wherein the first threshold and the second threshold are equal.

[0336] 57. A method according to clause 55, wherein the first threshold is greater than the second threshold.

[0337] 58. A method according to clause 57, wherein:

[0338] the first detected charge exceeds the first threshold and is passed to the signal readout path,

[0339] The first detected charge then drops to an intermediate range below the first threshold and above the second threshold,

[0340] The method further comprises:

[0341] In response to the first detection charge falling within the intermediate range, the detection charge continues to be transferred to the signal readout path.

[0342] 59. A method according to clause 57, wherein:

[0343] the second detected charge does not exceed the second threshold and is therefore prevented from passing to the signal readout path,

[0344] The second detected charge then rises to an intermediate range below the first threshold and above the second threshold,

[0345] The method further comprises:

[0346] In response to the second detection charge rising to the intermediate range, the detection charge continues to be prevented from being transferred to the signal readout path.

[0347] 60. A method according to clause 55, wherein:

[0348] The first sensing element is present in a first section of the sensing element;

[0349] Each sensing element in the first segment is coupled to an element bus switch element;

[0350] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0351] 61. The method of clause 60, wherein the first detected charge exceeds the first threshold and is passed to the signal readout path through a closing element bus switch element.

[0352] 62. A method according to clause 61, wherein:

[0353] The first section of the sensing element is adjacent to the second section of the sensing element;

[0354] the second segment of sensing elements comprises a third sensing element belonging to the first group; and

[0355] The first section of the sensing element and the second section of the sensing element are coupled to each other via an interconnecting switch element;

[0356] Wherein, by closing the interconnection switch element, the first detection charge is further transferred to the signal readout path.

[0357] 63. The method according to clause 55, wherein

[0358] The first sensor element is adjacent to the third sensor element, the third sensor element belongs to the first group; and

[0359] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0360] 64. The method of clause 63, wherein the first detected charge exceeds the first threshold and is transferred to the signal readout path by closing the inter-element switching element.

[0361] 65. A method according to clause 55, wherein:

[0362] The second sensing element is present within the first section of the sensing element;

[0363] Each sensing element in the first segment is coupled to an element bus switch element; and

[0364] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0365] 66. The method of clause 65, wherein the second detected charge is below the second threshold and is prevented from passing to the signal readout path by opening an element bus switch element in the first segment.

[0366] 67. A method according to clause 55, wherein

[0367] The second sensor element is adjacent to the third sensor element, the third sensor element belongs to the first group; and

[0368] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0369] 68. A method according to clause 67, wherein the second detected charge is below the second threshold and is prevented from passing to the signal readout path by opening the inter-element switching element.

[0370] 69. The method of clause 55, wherein the sensing element comprises a PIN diode.

[0371] 70. A method according to clause 55, wherein:

[0372] coupling the first element to the first group through the first threshold circuit; and

[0373] Decoupling the second element from the first group is performed by the second threshold circuit.

[0374] 71. The method of clause 55, wherein coupling the first element to the first group and decoupling the second element from the first group is performed by a single threshold circuit.

[0375] 72. A non-transitory computer-readable medium according to clause 72, storing a set of instructions executable by at least one processor of a device to cause the device to perform a method comprising:

[0376] receiving, by a sensing element of an electron detector, electrons from a plurality of secondary electron beams emitted by a sample in response to a plurality of primary beams of the multi-beam SEM interacting with the sample, each secondary beam being associated with a different one of the plurality of primary beams;

[0377] coupling a first group of the sensing elements of the electron detector corresponding to a first beam spot of one of the secondary electron beams based on the received electrons; and

[0378] coupling the first sensing element to the first group in response to a first detected charge at the first sensing element exceeding a first threshold, wherein coupling the first sensing element to the first group enables charge to be transferred from the first sensing element to a signal readout path of the first group; or

[0379] Decoupling the second sensing element from the first group in response to a second detected charge at the second sensing element being below a second threshold, wherein decoupling the second sensing element from the first group prevents charge from passing from the second sensing element to the signal readout path of the first group.

[0380] 73. The non-transitory computer-readable medium of clause 72, wherein the first threshold and the second threshold are equal.

[0381] 74. The non-transitory computer-readable medium of clause 72, wherein the first threshold is greater than the second threshold.

[0382] 75. The non-transitory computer-readable medium of clause 74, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0383] In response to the following operations, the detection charge continues to be transferred to the signal readout path:

[0384] The first detected charge exceeds the first threshold and is passed to the signal readout path; and

[0385] The first detected charge then drops to an intermediate range below the first threshold and above the second threshold.

[0386] 76. The non-transitory computer-readable medium of clause 74, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0387] The detection charge continues to be prevented from passing to the switching network in response to:

[0388] the second detected charge does not exceed the second threshold and is prevented from passing to the signal readout path; and

[0389] The second detected charge then rises to an intermediate range below the first threshold and above the second threshold.

[0390] 77. The non-transitory computer-readable medium of clause 72, wherein:

[0391] The first sensing element is present in a first section of the sensing element;

[0392] Each sensing element in the first segment is coupled to an element bus switch element; and

[0393] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0394] 78. The non-transitory computer-readable medium of clause 77, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0395] In response to the first detected charge exceeding the first threshold, the first detected charge is transferred to the signal readout path by closing the element bus switch element.

[0396] 79. The non-transitory computer-readable medium of clause 78, wherein:

[0397] The first section of the sensing element is adjacent to the second section of the sensing element;

[0398] the second segment of sensing elements comprises a third sensing element belonging to the first group; and

[0399] The first section of the sensing element and the second section of the sensing element are coupled to each other via an interconnecting switch element;

[0400] The instruction set capable of being executed by at least one processor of the device is configured to cause the device to further perform:

[0401] The first detection charge is further transferred to the signal readout path by closing the interconnection switch element.

[0402] 80. The non-transitory computer-readable medium of clause 72, wherein:

[0403] The first sensor element is adjacent to the third sensor element, the third sensor element belongs to the first group; and

[0404] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0405] 81. The non-transitory computer-readable medium of clause 80, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0406] In response to the first detection charge exceeding the first threshold, the first detection charge is transferred to the signal readout path by closing the inter-element switching element.

[0407] 82. The non-transitory computer-readable medium of clause 72, wherein:

[0408] The second sensing element is present within the first section of the sensing element;

[0409] Each sensing element in the first segment is coupled to an element bus switch element; and

[0410] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0411] 83. The non-transitory computer-readable medium of clause 82, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0412] In response to the second detected charge being lower than the second threshold, the second detected charge is prevented from passing to the signal readout path by opening an element bus switch element in the first segment.

[0413] 84. The non-transitory computer-readable medium of clause 72, wherein:

[0414] The second sensor element is adjacent to the third sensor element, the third sensor element belongs to the first group; and

[0415] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0416] 85. The non-transitory computer-readable medium of clause 84, wherein the set of instructions executable by at least one processor of an apparatus is configured to cause the apparatus to further perform:

[0417] In response to the second detection charge being lower than the second threshold, the second detection charge is prevented from being transferred to the signal readout path by opening the inter-element switching element.

[0418] 86. The non-transitory computer-readable medium of clause 72, wherein the sensing element comprises a PIN diode.

[0419] 87. The non-transitory computer-readable medium of clause 72, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0420] coupling the first element to the first group via the first threshold circuit; and

[0421] The second element is decoupled from the first group by the second threshold circuit.

[0422] 88. The non-transitory computer-readable medium of clause 72, wherein the set of instructions executable by at least one processor of the device is configured to cause the device to further perform:

[0423] The first element is coupled to the first group and the second element is decoupled from the first group by a single threshold circuit.

[0424] 89. A system comprising:

[0425] a charged particle detector comprising a plurality of sensing elements receiving electrons of a plurality of secondary electron beams emitted by a sample in response to a plurality of primary beams of the multi-beam scanning electron microscope (SEM) interacting with the sample, each of the secondary beams being associated with a different one of the plurality of primary beams; and

[0426] A controller having circuitry configured to:

[0427] coupling a first group of the sensing elements of the electron detector corresponding to a first beam spot of one of the secondary electron beams based on the received electrons; and

[0428] coupling the first sensing element to the first group in response to a first detected charge at the first sensing element exceeding a first threshold, wherein coupling the first sensing element to the first group enables charge to be transferred from the first sensing element to a signal readout path of the first group; or

[0429] The second sensing element is decoupled from the first group in response to a second detected charge at the second sensing element being below a second threshold, wherein decoupling the second element from the first group prevents charge from passing from the second sensing element to the signal readout path of the first group.

[0430] 90. A system according to clause 89, wherein the first threshold and the second threshold are equal.

[0431] 91. A system according to clause 89, wherein the first threshold is greater than the second threshold.

[0432] 92. The system of clause 91, wherein the controller has circuitry configured to further perform:

[0433] The detection charge is continued to be passed to the signal readout path in response to:

[0434] The first detected charge exceeds the first threshold and is passed to the signal readout path; and

[0435] The first detected charge then drops to an intermediate range below the first threshold and above the second threshold.

[0436] 93. The system of clause 91, wherein the controller has circuitry configured to further:

[0437] The detection charge continues to be prevented from passing to the switching network in response to:

[0438] the second detected charge does not exceed the second threshold and is prevented from passing to the signal readout path; and

[0439] The second detected charge then rises to an intermediate range below the first threshold and above the second threshold.

[0440] 94. The system of clause 89, wherein:

[0441] The first sensing element is present in a first section of the sensing element;

[0442] Each sensing element in the first segment is coupled to an element bus switch element; and

[0443] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0444] 95. The system of clause 94, wherein the controller has circuitry configured to further perform the following:

[0445] In response to the first detected charge exceeding the first threshold, the first detected charge is transferred to the signal readout path by closing the element bus switch element.

[0446] 96. A system according to clause 95, wherein:

[0447] The first section of the sensing element is adjacent to the second section of the sensing element;

[0448] the second segment of sensing elements comprises a third sensing element belonging to the first group; and

[0449] The first section of the sensing element and the second section of the sensing element are coupled to each other via an interconnecting switch element;

[0450] Wherein, the controller has a circuit system configured to further perform the following:

[0451] The first detection charge is further transferred to the signal readout path by closing the interconnection switch element.

[0452] 97. A system according to clause 89, wherein

[0453] The first sensor element is adjacent to the third sensor element, the third sensor element belongs to the first group; and

[0454] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0455] 98. The system of clause 97, wherein the controller has circuitry configured to further perform the following:

[0456] In response to the first detection charge exceeding the first threshold, the first detection charge is transferred to the signal readout path by closing the inter-element switch element.

[0457] 99. The system of clause 89, wherein:

[0458] The second sensing element is present within the first section of the sensing element;

[0459] Each sensing element in the first segment is coupled to an element bus switch element; and

[0460] Each element bus switch element in the first segment is configured to couple its corresponding sensing element to a common node of the first segment.

[0461] 100. The system of clause 99, wherein the controller has circuitry configured to further perform:

[0462] In response to the second detected charge being lower than the second threshold, the second detected charge is prevented from passing to the signal readout path by opening an element bus switch element in the first segment.

[0463] 101. A system according to clause 89, wherein

[0464] The second sensor element is adjacent to a third sensor element, the third sensor element belonging to the first group; and

[0465] The first sensing element is configured to be coupled to the third sensing element via an inter-element switching element.

[0466] 102. The system of clause 101, wherein the controller has circuitry configured to further perform the following:

[0467] In response to the second detection charge being lower than the second threshold, the second detection charge is prevented from being transferred to the signal readout path by opening the inter-element switching element.

[0468] 103. The system of clause 89, wherein the sensing element comprises a PIN diode.

[0469] 104. The system of clause 89, wherein the controller comprises circuitry configured to further perform:

[0470] coupling the first sensing element to the first group via the first threshold circuit; and

[0471] The second sensing element is decoupled from the first group by the second threshold circuit.

[0472] 105. The system of clause 89, wherein the controller comprises circuitry configured to further perform:

[0473] The first sensing element is coupled to the first group and the second sensing element is decoupled from the first group through a single threshold circuit.

[0474] 106. A method of updating a set of sensing elements in a charged particle detector, the method comprising:

[0475] irradiating a sample to produce a secondary beam spot on the charged particle detector, the secondary beam spot overlapping the sensor element group;

[0476] identifying a first sensor element as a candidate for updating a grouping state of the first sensor element; and

[0477] initiating a threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector;

[0478] The threshold operation includes comparing the signal level of the first sensing element with a threshold value.

[0479] 107. The method according to clause 106, further comprising:

[0480] Based on the comparison result, the first switch element is actuated to update the grouping status of the sensor elements.

[0481] 108. The method of clause 106, wherein the first switching element is in an open state to allow the switching element to conduct current before initiating the threshold operation, the method further comprising:

[0482] By maintaining the first switch element in the open state, the grouping state of the sensor elements is kept unchanged.

[0483] 109. The method of clause 106, wherein the first switching element is in a closed state to prevent the switching element from conducting current before initiating the threshold operation, the method further comprising:

[0484] By maintaining the first switch element in a closed state, the grouping state of the sensor elements is kept unchanged.

[0485] 110. A detector comprising:

[0486] substrate;

[0487] a plurality of switch elements formed on the substrate and configured to form a switch matrix, the switch matrix having a plurality of inputs, each of the inputs configured to be connected to a different one of a plurality of sensor elements, each of the sensor elements configured to generate a signal in response to the arrival of energy at the sensor element, the switch matrix configured to combine groups of signals generated from groups of sensor elements associated with beam spots formed on the detector; and

[0488] a plurality of transistors forming a plurality of threshold circuits, each of the threshold circuits being coupled to a different one of the plurality of sensing elements,

[0489] A first threshold circuit of the plurality of threshold circuits is coupled to a first sensor element of the plurality of sensor elements and is configured to actuate a first switch element of the switch matrix based on a comparison of a signal level of the first sensor element with a threshold value.

[0490] 111. An apparatus according to clause 110, wherein the detector is configured to detect electrons and the arrival of the energy at the sensing element comprises an electron landing event.

[0491] 112. The apparatus of clause 110, wherein the detector is configured to detect protons and the arrival of the energy at the sensing element comprises a proton landing event.

[0492] 113. An apparatus as described in clause 110, wherein the detector is configured to detect photons and the arrival of the energy at the sensing element comprises a photon landing event.

[0493] 114. A method for updating a sensor element group in a detector, the method comprising:

[0494] irradiating a sample to produce a secondary beam spot on the detector, the secondary beam spot overlapping the sensor element group;

[0495] identifying a first sensing element as a candidate for updating a grouping state of the first sensing element, the sensing element being configured to generate a signal in response to arrival of energy at the sensing element;

[0496] initiating a threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switching matrix of the detector;

[0497] wherein the threshold operation comprises comparing the signal level of the first sensing element with a threshold value; and

[0498] Based on the comparison result, the first switch element is actuated to update the grouping status of the sensor elements.

[0499] 115. A method according to clause 114, wherein the detector is configured to detect electrons and the arrival of the energy at the sensing element comprises an electron landing event.

[0500] 116. The method of clause 114, wherein the detector is configured to detect protons and the arrival of the energy at the sensing element comprises a proton landing event.

[0501] 117. A method according to clause 114, wherein the detector is configured to detect photons and the arrival of the energy at the sensing element comprises a photon landing event.

[0502] 118. A system comprising:

[0503] a charged particle detector comprising a plurality of sensing elements and configured to be exposed to a beam spot overlapping a set of sensing elements;

[0504] The controller has circuitry configured to update the set of sensing elements in the charged particle detector by:

[0505] identifying the first sensor element as a candidate for updating a grouping state of the first sensor element based on a proximity of the first sensor element to a boundary of the sensor element group;

[0506] initiating a threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector;

[0507] wherein the threshold operation comprises comparing the signal level of the first sensing element with a threshold; and

[0508] Based on the comparison result, the first switch element is actuated to update the grouping status of the sensor elements.

[0509] 119. A system according to clause 118, wherein identifying the first sensor element as a candidate for updating the grouping state of the first sensor element based on the proximity of the first sensor element to the boundary of the sensor element group includes: determining whether a neighboring sensor element adjacent to the first sensor element has a different grouping state than the first sensor element.

[0510] 120. The system of clause 119, wherein the first sensing element is a grouped sensing element and the adjacent sensing element is an ungrouped sensing element.

[0511] 121. The system of clause 119, wherein the first sensing element is an ungrouped sensing element and the adjacent sensing elements are grouped sensing elements.

[0512] 122. The system of clause 118, wherein:

[0513] The comparing includes determining whether the signal level of the first sensing element exceeds a threshold;

[0514] Actuating the first switching element includes closing the first switching element so that the first switching element conducts current; and

[0515] Updating the grouping state of the first sensor element includes: adding the first sensor element to the sensor element group.

[0516] 123. A system according to clause 122,

[0517] wherein the threshold is a first threshold,

[0518] wherein the controller has circuitry configured to further perform the following:

[0519] determining that the signal level of the first sensing element is below a second threshold;

[0520] opening the first switching element to prevent the first switching element from conducting current; and

[0521] The grouping state of the first sensor element is updated to remove the first sensor element from the sensor element group.

[0522] 124. The system of clause 122, the controller having circuitry configured to further perform:

[0523] After the first sensor element is added to the sensor element group, the second sensor element is identified as a candidate for updating a grouping state of the second sensor element, the second sensor element being adjacent to the first sensor element.

[0524] 125. The system of clause 124, the controller having circuitry configured to further perform:

[0525] initiating an additional threshold operation of the second sensing element by a second threshold circuit coupled to the second sensing element and a second switching element of the switching matrix of the detector;

[0526] wherein the further threshold operation comprises comparing the signal level of the second sensing element to a further threshold; and

[0527] Based on the comparison with the further threshold value, the second switching element is actuated to update the grouping state of the sensor elements.

[0528] 126. A system according to clause 124, wherein:

[0529] The comparing includes determining whether the signal level of the first sensing element is below the threshold;

[0530] actuating the first switching element comprises opening the first switching element to prevent the first switching element from conducting current; and

[0531] Updating the grouping status of the first sensor element includes removing the first sensor element from the sensor element group.

[0532] 127. A system according to clause 126,

[0533] wherein the threshold is a second threshold,

[0534] Wherein, the controller has a circuit system, and the circuit system is configured to further perform:

[0535] determining that the signal level of the first sensing element exceeds a first threshold;

[0536] closing the first switching element so that the first switching element conducts current; and

[0537] The grouping state of the first sensor element is updated to add the first sensor element to the sensor element group.

[0538] 128. The system of clause 126, the controller having circuitry configured to further perform:

[0539] After the first sensor element is removed from the sensor element group, a candidate state of the second sensor element is terminated, the second sensor element being adjacent to the first sensor element and not adjacent to a boundary of the sensor element group.

[0540] 129. The system of clause 118, wherein the threshold operation continues until the threshold is met or the threshold operation is terminated by a controller of the charged particle detector.

[0541] 130. The system of clause 118, wherein the proximity of the first sensing element to a boundary of the group of sensing elements comprises the first sensing element being adjacent to a boundary of the group of sensing elements.

[0542] 131. The system of clause 118, wherein the first sensing element comprises a PIN diode.

[0543] 132. A method of updating a set of sensing elements in a charged particle detector, the method comprising:

[0544] irradiating a sample to produce a secondary beam spot on the charged particle detector, the secondary beam spot overlapping the sensor element group;

[0545] identifying a first sensor element as a candidate for updating a grouping state of the first sensor element;

[0546] identifying a second sensor element as a candidate for updating a grouping state of the second sensor element, the second sensor element being adjacent to the first sensor element;

[0547] initiating a first threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector; and

[0548] initiating a second threshold operation of the second sensing element by the second threshold circuit coupled to the second sensing element and a second switch element of the switch matrix of the charged particle detector;

[0549] wherein the first threshold operation comprises comparing the signal level of the first sensing element with a first threshold; and

[0550] The second threshold operation includes comparing the signal level of the second sensing element to a second threshold value that is different from the first threshold value.

[0551] 133. A method according to clause 132, wherein:

[0552] The first sensor element is a grouped sensor element located inside a boundary of the sensor element group;

[0553] The second sensor elements are ungrouped sensor elements located outside the boundary of the sensor element group.

[0554] 134. The method according to clause 133, further comprising:

[0555] In response to the signal level of the first sensing element being lower than the first threshold in the first threshold operation, the grouping state of the first sensing element is updated by opening the first switching element to remove the first sensing element from the sensing element group.

[0556] 135. The method according to clause 134, further comprising:

[0557] In response to removing the first sensing element from the set of sensing elements, a second threshold operation of the second threshold circuit is terminated.

[0558] 136. The method according to clause 134, further comprising:

[0559] initiating a third threshold operation of the first sensing element by the first threshold circuit in response to removing the first sensing element from the set of sensing elements;

[0560] The third threshold operation includes comparing the signal level of the first sensing element with the second threshold.

[0561] 137. The method according to clause 133, further comprising:

[0562] In response to the signal level of the second sensing element exceeding the second threshold in the second threshold operation, the grouping state of the second sensing element is updated by closing the second switch element to add the second sensing element to the sensing element group.

[0563] 138. The method according to clause 137, further comprising:

[0564] In response to adding the second sensing element to the sensing element group, the first threshold operation of the first threshold circuit is terminated.

[0565] 139. The method according to clause 137, further comprising:

[0566] initiating a third threshold operation of the second sensing element by the second threshold circuit in response to adding the second sensing element to the sensing element group;

[0567] The third threshold operation includes comparing the signal level of the second sensing element with the first threshold.

[0568] 140. The method according to clause 137, further comprising:

[0569] initiating a third threshold operation of the third sensing element by the third threshold circuit in response to adding the second sensing element to the sensing element group;

[0570] The third threshold operation includes comparing the signal level of the third sensing element with the second threshold.

[0571] 141. A method according to clause 132, wherein the second threshold is higher than the first threshold.

[0572] 142. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a device to cause the device to perform a method of updating a set of sensing elements based on a beam spot exposed on the charged particle detector, the method comprising:

[0573] identifying a first sensor element as a candidate for updating a grouping state of the first sensor element;

[0574] identifying a second sensor element as a candidate for updating a grouping state of the second sensor element, the second sensor element being adjacent to the first sensor element;

[0575] initiating a first threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector;

[0576] initiating a second threshold operation of the second sensing element by the second threshold circuit coupled to the second sensing element and a second switch element of the switch matrix of the charged particle detector; wherein the first threshold operation comprises comparing the signal level of the first sensing element to the first threshold; and

[0577] The second threshold operation includes comparing the signal level of the second sensing element to a second threshold value that is different from the first threshold value.

[0578] 143. The non-transitory computer-readable medium of clause 142, wherein:

[0579] The first sensor element is a grouped sensor element located inside a boundary of the sensor element group;

[0580] The second sensor elements are ungrouped sensor elements located outside the boundary of the sensor element group.

[0581] 144. The non-transitory computer-readable medium of clause 143, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0582] In response to the signal level of the first sensing element being lower than the first threshold in the first threshold operation, the grouping state of the first sensing element is updated by opening the first switching element to remove the first sensing element from the sensing element group.

[0583] 145. The non-transitory computer-readable medium of clause 144, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0584] In response to removing the first sensing element from the set of sensing elements, the second threshold operation of the second threshold circuit is terminated.

[0585] 146. The non-transitory computer-readable medium of clause 144, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0586] initiating a third threshold operation of the first sensing element by the first threshold circuit in response to removing the first sensing element from the set of sensing elements;

[0587] The third threshold operation includes comparing the signal level of the first sensing element with the second threshold.

[0588] 147. The non-transitory computer-readable medium of clause 143, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0589] In response to the signal level of the second sensing element exceeding the second threshold in the second threshold operation, the grouping state of the second sensing element is updated by closing the second switch element to add the second sensing element to the sensing element group.

[0590] 148. The non-transitory computer-readable medium of clause 147, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0591] In response to adding the second sensing element to the sensing element group, a first threshold operation of the first threshold circuit is terminated.

[0592] 149. The non-transitory computer-readable medium of clause 147, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0593] initiating a third threshold operation of the second sensing element by the second threshold circuit in response to adding the second sensing element to the sensing element group;

[0594] The third threshold operation includes comparing the signal level of the second sensing element with the first threshold.

[0595] 150. The non-transitory computer-readable medium of clause 147, wherein the set of instructions executable by at least one processor of the apparatus is configured to cause the apparatus to further perform:

[0596] initiating a third threshold operation of a third sensor element by the third threshold circuit in response to adding the second sensor element to the sensor element group;

[0597] The third threshold operation includes comparing the signal level of the third sensing element with the second threshold.

[0598] 151. A non-transitory computer-readable medium as described in claim 142, wherein the second threshold is higher than the first threshold.

[0599] 152. A system comprising:

[0600] a charged particle detector comprising a plurality of sensing elements and configured to be exposed to a beam spot overlapping a group of sensing elements;

[0601] The controller has circuitry configured to update a set of sensing elements in the charged particle detector by:

[0602] identifying the first sensor element as a candidate for updating a grouping state of the first sensor element;

[0603] identifying the second sensor element as a candidate for updating a grouping state of the second sensor element, the second sensor element being adjacent to the first sensor element;

[0604] initiating a first threshold operation of the first sensing element by a first threshold circuit coupled to the first sensing element and a first switching element of a switch matrix of the charged particle detector;

[0605] initiating a second threshold operation of the second sensing element by a second threshold circuit coupled to the second sensing element and a second switch element of the switch matrix of the charged particle detector; wherein the first threshold operation comprises comparing a signal level of the first sensing element to the first threshold; and

[0606] The second threshold operation includes comparing the signal level of the second sensing element to a second threshold value that is different from the first threshold value.

[0607] 153. A system according to clause 152, wherein:

[0608] The first sensor element is a grouped sensor element located inside a boundary of the sensor element group;

[0609] The second sensor elements are ungrouped sensor elements located outside the boundary of the sensor element group.

[0610] 154. The system of clause 153, the controller having circuitry configured to further perform:

[0611] In response to the signal level of the first sensing element being lower than the first threshold in the first threshold operation, the grouping state of the first sensing element is updated by opening the first switching element to remove the first sensing element from the sensing element group.

[0612] 155. The system of clause 154, the controller having circuitry configured to further perform:

[0613] In response to removing the first sensing element from the set of sensing elements, the second threshold operation of the second threshold circuit is terminated.

[0614] 156. The system of clause 154, the controller having circuitry configured to further perform:

[0615] initiating a third threshold operation of the first sensing element by the first threshold circuit in response to removing the first sensing element from the set of sensing elements;

[0616] The third threshold operation includes comparing the signal level of the first sensing element with the second threshold.

[0617] 157. The system of clause 153, the controller having circuitry configured to further perform:

[0618] In response to the signal level of the second sensing element exceeding the second threshold in the second threshold operation, the grouping state of the second sensing element is updated by closing the second switch element to add the second sensing element to the sensing element group.

[0619] 158. The system of clause 157, the controller having circuitry configured to further perform:

[0620] In response to adding the second sensing element to the sensing element group, the first threshold operation of the first threshold circuit is terminated.

[0621] 159. The system of clause 157, the controller having circuitry configured to further perform:

[0622] initiating a third threshold operation of the second sensing element by the second threshold circuit in response to adding the second sensing element to the sensing element group;

[0623] The third threshold operation includes comparing the signal level of the second sensing element with the first threshold.

[0624] 160. The system of clause 157, the controller having circuitry configured to further perform:

[0625] initiating a third threshold operation of a third sensor element by a third threshold circuit in response to adding the second sensor element to the sensor element group;

[0626] The third threshold operation includes comparing the signal level of the third sensing element with the second threshold.

[0627] 161. A system according to clause 152, wherein the second threshold is higher than the first threshold.

[0628] 162. A charged particle detector comprising:

[0629] substrate;

[0630] a plurality of switch elements formed on the substrate and configured to form a switch matrix, the switch matrix having a plurality of inputs, each of the inputs configured to be connected to a different one of the plurality of sensor elements, each of the sensor elements configured to generate a signal in response to a charged particle impinging on the sensor element, the switch matrix configured to combine groups of signals generated from groups of the sensor elements associated with a charged particle beam spot formed on the charged particle detector; and

[0631] a plurality of threshold circuits, each of the threshold circuits being coupled to a different one of the plurality of sensing elements,

[0632] wherein a first threshold circuit of the plurality of threshold circuits is coupled to a first sensor element of the plurality of sensor elements and is configured to actuate a first switch element of the switch matrix based on a comparison of a signal level of the first sensor element with a first threshold value;

[0633] wherein a second threshold circuit of the plurality of threshold circuits is coupled to a second sensing element of the plurality of sensing elements and is configured to actuate a second switch element of the switch matrix based on a comparison of a signal level of the second sensing element with a second threshold value;

[0634] wherein the first sensing element is adjacent to the second sensing element; and

[0635] The first threshold is different from the second threshold.

[0636] 163. A charged particle detector according to clause 162, wherein the first threshold circuit is configured to close the first switching element in response to the signal level of the first sensing element exceeding the first threshold so that the first switching element conducts current.

[0637] 164. A charged particle detector according to clause 163, wherein the first sensor element is added to the sensor element group by closing the first switching element by the first threshold circuit so that the signal from the first sensor element is combined with the signal group generated from the sensor element group.

[0638] 165. A charged particle detector according to clause 164, wherein

[0639] The second sensor element is in a state of being grouped together with the sensor element group; and

[0640] The second sensor element is coupled to the first sensor element through the first switch element.

[0641] 166. A charged particle detector according to clause 164, wherein

[0642] In response to the first sensing element being added to the sensing element group, the first threshold circuit is configured to actuate the first switching element of the switch matrix based on a comparison of the signal level of the first sensing element and the second threshold.

[0643] 167. A charged particle detector according to clause 162, wherein the second threshold circuit is configured to open the second switching element in response to the signal level of the second sensing element being lower than the second threshold to prevent the second switching element from conducting current.

[0644] 168. A charged particle detector according to clause 167, wherein the second switching element is opened by the second threshold circuit to remove the second sensing element from the sensing element group to prevent the signal from the second sensing element from combining with the signal group generated from the sensing element group.

[0645] 169. A charged particle detector according to clause 168, wherein

[0646] In response to the second sensing element being removed from the set of sensing elements, the first threshold circuit is configured to terminate the comparison of the signal level of the first sensing element with the first threshold.

[0647] 170. A charged particle detector according to clause 168, wherein

[0648] In response to the second sensing element being removed from the sensing element group, the second threshold circuit is configured to actuate the second switching element of the switch matrix based on a comparison of the signal level of the second sensing element and the first threshold.

[0649] 171. A charged particle detector according to clause 162, wherein the first threshold circuit is configured to initiate a comparison of the signal level of the first sensor element with the first threshold in response to the first sensor element being adjacent to an outer boundary of the sensor element group.

[0650] 172. A charged particle detector according to clause 12, wherein the second threshold circuit is configured to initiate a comparison of the signal level of the second sensing element with the second threshold in response to the second sensing element being adjacent to an internal boundary of the sensing element group.

[0651] 173. A charged particle detector according to claim 1, wherein the substrate includes the plurality of transistors.

[0652] It should be understood that the embodiments of the present disclosure are not limited to the exact configurations described above and shown in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The present disclosure has been described in conjunction with various embodiments, and other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The description and examples should be regarded as exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

Claims

1. A charged particle detector, comprising: substrate; a plurality of switch elements formed on the substrate and configured to form a switch matrix, the switch matrix having a plurality of inputs, each of the inputs configured to be connected to a different one of a plurality of sensor elements, each of the sensor elements configured to generate a signal in response to a charged particle impinging on the sensor element, the switch matrix configured to combine a group of signals generated from a group of sensor elements associated with a charged particle beam spot formed on the charged particle detector; as well as a plurality of threshold circuits, each of the threshold circuits being coupled to a different one of the plurality of sensing elements, wherein a first threshold circuit of the plurality of threshold circuits is coupled to a first sensor element of the plurality of sensor elements and is configured to actuate a first switch element of the switch matrix based on a comparison of a signal level of the first sensor element with a threshold value; wherein the first sensor element is configured to be identified as a candidate for one of: being added to the sensor element group or being removed from the sensor element group based on the proximity of the first sensor element to a boundary of the sensor element group; and The first threshold circuit is configured to initiate the comparison in response to the first sensing element being identified as the candidate. 2 . The charged particle detector of claim 1 , wherein the first threshold circuit is configured to close the first switch element in response to the signal level of the first sensing element exceeding the threshold value so that the first switch element conducts current.

3. A charged particle detector according to claim 2, wherein the first sensor element is added to the sensor element group by closing the first switch element by the first threshold circuit so that the signal from the first sensor element is combined with the signal group generated from the sensor element group.

4. The charged particle detector according to claim 3, wherein the threshold is a first threshold, and The first threshold circuit is configured to open the first switching element to prevent the first switching element from conducting current in response to the signal level of the first sensing element falling below a second threshold, wherein the second threshold is lower than the first threshold.

5. A charged particle detector according to claim 4, wherein the first sensor element is removed from the sensor element group by the opening of the first switch element by the first threshold circuit to prevent the signal from the first sensor element from combining with the signal group generated from the sensor element group.

6. The charged particle detector of claim 1, wherein the first threshold circuit is configured to open the first switching element in response to the signal level of the first sensing element falling below the threshold to prevent the first switching element from conducting current.

7. A charged particle detector according to claim 6, wherein the first sensor element is removed from the sensor element group by the opening of the first switch element by the first threshold circuit to prevent the signal from the first sensor element from combining with the signal group generated from the sensor element group.

8. The charged particle detector according to claim 7, wherein the threshold is a second threshold, and The first threshold circuit is configured to close the first switch element in response to the signal level of the first sensing element exceeding a first threshold so that the first switch element conducts current, wherein the first threshold is higher than the second threshold.

9. A charged particle detector according to claim 8, wherein the first sensor element is added to the sensor element group by closing the first switch element by the first threshold circuit so that the signal from the first sensor element is combined with the signal group generated from the sensor element group.

10. The charged particle detector according to claim 1, further comprising: a second sensing element adjacent to the first sensing element; The proximity of the first sensor element to a boundary of the sensor element group is determined based on the first sensor element having a different grouping state from the second sensor element.

11. The charged particle detector according to claim 10, wherein: The first sensor element is in a state of being grouped together with the sensor element group; The second sensor element is in a state of not being grouped together with the sensor element group; The first sensor element is a candidate for removal from the set of sensor elements; and The second sensor element is a candidate to be added to the group of sensor elements.

12. The charged particle detector of claim 11, wherein the first threshold circuit is configured to remove the first sensing element from the sensing element group by opening the first switching element in response to the first signal level being below the threshold.

13. The charged particle detector of claim 10, wherein: The first sensor element is in a state of not being grouped together with the sensor element group; The second sensor element is in a state of being grouped together with the sensor element group; The first sensor element is a candidate to be added to the set of sensor elements; and The second sensor element is a candidate for removal from the set of sensor elements.

14. The charged particle detector of claim 13, wherein the first threshold circuit is configured to add the first sensing element to the sensing element group by closing the first switching element in response to the first signal level exceeding the threshold.

15. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a device to cause the device to perform a method comprising: receiving, by a sensing element of an electron detector, electrons from a plurality of secondary electron beams emitted by a sample in response to a plurality of primary beams of the multi-beam SEM interacting with the sample, each of the secondary electron beams being associated with a different one of the plurality of primary beams; coupling a first group of the sensing elements of the electron detector corresponding to a first beam spot of one of the secondary electron beams based on the received electrons; as well as coupling the first sensing element to the first group in response to a first detected charge at the first sensing element exceeding a first threshold, wherein coupling the first sensing element to the first group enables charge to pass from the first sensing element to a signal readout path of the first group; or Decoupling the second sensing element from the first group in response to a second detected charge at the second sensing element falling below a second threshold, wherein decoupling the second sensing element from the first group prevents charge from passing from the second sensing element to the signal readout path of the first group.

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