Image mode resolution enhancement for electron beam detector

Abstract

A charged particle detector includes a plurality of sensing elements, wherein each sensing element is further divided into sub-sensing elements. The sub-sensing elements may be individually addressed during high-resolution image acquisition in an image mode and may be grouped together during high-speed detection in a beam mode. This arrangement allows for a selectable compromise between velocity and resolution without introducing significant parasitic parameters.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application No. 63 / 368,604, filed on July 15, 2022, and the entire contents of that U.S. application are incorporated herein by reference. Technical Field

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

[0004] Detectors can be used to physically sense observable phenomena. For example, some charged particle beam tools such as electron microscopes include detectors that receive charged particles projected from a sample and output detection signals. The detection signal can be used to reconstruct an image of the sample structure being detected, and can be used, for example, to reveal defects in the sample. The detection of defects in the sample is increasingly important in the manufacture of semiconductor devices that can include a large number of densely packed miniaturized integrated circuit (IC) components. Inspection systems can be provided for this purpose. For example, a charged particle (e.g., electron) beam microscope (such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM)) with a resolution down to less than a nanometer is used as a practical tool for inspecting IC components with a feature size of sub-100 nanometers. The electron microscope works by irradiating the sample with an electron beam and then detecting secondary or backscattered electrons (or other types of secondary particles) on the 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 can be useful because it can allow 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 zones of the detector associated with different beam spots. Each zone can form its own group of sensing elements for detecting a separate beam spot.

[0006] To form detection groups for different beam spots, a typical process includes two steps. First, an image of the detector surface is acquired. In the so-called "image 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 spot 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 groups of sensing elements can be selected so that the dividing lines of the groups are close to the boundaries of the beam spots. This selected group of sensing elements can be used later to detect the beam spots during "beam mode". Summary of the invention

[0007] Embodiments of the present disclosure provide systems and methods for charged particle detection.

[0008] Some embodiments include a charged particle detector configured to operate in an image mode or a beam mode. The charged particle detector may include a substrate including a first group of multiple sub-sensing elements configured to convert a charged particle landing event into an electrical signal. Each of the sub-sensing elements in the first group of multiple sub-sensing elements may be coupled to a switch on a first side of the sub-sensing element and may be coupled to a first sensing element node of a first sensing element on a second side of the sub-sensing element. Each of the sub-sensing elements in the first group of multiple sub-sensing elements may be configured to generate an image mode sub-pixel signal when the charged particle detector operates in the image mode, wherein each image mode sub-pixel signal may be individually acquired by a signal processing circuit of the charged particle detector in the image mode.

[0009] The first plurality of sub-sensing elements may be configured to generate a first beam mode sensing element signal when the charged particle detector is operated in the beam mode. A switch coupled to each of the sub-sensing elements in the first plurality of sub-sensing elements may be closed in the beam mode, so that the first beam mode sensing element signal can be acquired by a signal processing circuit of the charged particle detector in the beam mode.

[0010] Some embodiments include a non-transitory computer-readable medium storing an instruction set that can be executed by at least one processor of a charged particle beam device to cause the device to perform a method. The method may include addressing a first sensing element of a plurality of sensing elements of a charged particle beam detector by connecting the first sensing element to a signal readout path of the charged particle beam device. The first sensing element may include a first group of multiple sub-sensing elements. Each sub-sensing element may be configured to convert a charged particle landing event into an electrical signal. Each of the sub-sensing elements in the first group of multiple sub-sensing elements may be coupled to a switch on a first side of the sub-sensing element, and may be coupled to a first sensing element node of the first sensing element on a second side of the sub-sensing element.

[0011] The method may also include, when addressing the first sensing element, individually addressing each sub-sensing element of the first sensing element by sequentially turning on and off each switch coupled to each sub-sensing element one at a time to individually connect each sub-sensing element of the first sensing element to the signal readout path. The method may also include performing adjustments to the charged particle beam device based on a signal obtained from the first sensing element on the signal readout path. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram illustrating an exemplary charged particle beam inspection system consistent with embodiments of the present disclosure.

[0013] Figure 2 It is consistent with the embodiment of the present disclosure and can be Figure 1 A diagram of an exemplary multi-beam tool that is a portion of an exemplary charged particle beam inspection system.

[0014] FIG. 3A to FIG. 3B is a representation of a charged particle detector consistent with an embodiment of the present disclosure.

[0015] Figure 4A is a representation of the surface of a charged particle detector according to a comparative embodiment.

[0016] Figure 4B According to the comparative example Figure 4A Representation of the beam mode operation of the charged particle detector surface.

[0017] Figure 4C is a representation of a detector chip circuit design according to a comparative embodiment.

[0018] Figure 5A A charged particle detector surface consistent with an embodiment of the present disclosure is illustrated.

[0019] Figure 5B The diagram is consistent with the embodiment of the present disclosure. Figure 5A The charged particle detector is operated in beam mode on the surface of the detector.

[0020] Figure 5C A detector chip circuit design consistent with an embodiment of the present disclosure is shown.

[0021] FIG. 6A to FIG. 6C An example of a detector chip circuit design consistent with an embodiment of the present disclosure is illustrated.

[0022] Figure 7 A switch arrangement of a sense element circuit consistent with an embodiment of the present disclosure is illustrated.

[0023] FIG. 8A to FIG. 8B Illustration of switching elements in a detector chip circuit design consistent with an embodiment of the present disclosure.

[0024] Fig. 9 An exemplary grouping arrangement of sub-sensing elements in a charged particle detector surface consistent with embodiments of the present disclosure is illustrated.

[0025] Fig.10is a flow chart of an exemplary method of generating a charged particle detection signal consistent with embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments set forth in the following description of exemplary embodiments do not represent all embodiments consistent with the present disclosure. Rather, they are merely examples of devices and methods consistent with aspects related to the subject matter recited in the accompanying 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 similarly applied. In addition, other imaging systems may be used, such as optical imaging, light detection, x-ray detection, etc.

[0027] Electronic devices consist of circuits formed on a sheet of semiconductor material called a substrate. The semiconductor material may include, for example, silicon, gallium arsenide, indium phosphide, or silicon germanium. Many circuits may be formed together on the same silicon wafer and are called integrated circuits or ICs. The size of these circuits has been significantly reduced so that many of these circuits can be mounted on a substrate. For example, in a smartphone, an IC chip may be the size of a thumbnail and may include more than 2 billion transistors, each of which is less than 1 / 1000 the size of a human hair.

[0028] Manufacturing these ICs with very small structures or components is a complex, time-consuming and expensive process that often involves hundreds of individual steps. An error in even one step may cause a defect in the finished IC that renders the finished IC useless. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process, i.e., to improve the overall yield of the process.

[0029] One element of improving yield is to monitor the chip manufacturing process to ensure that it is producing a sufficient number of functional integrated circuits. One way to monitor the process is to inspect the chip circuit structure at different stages of its formation. Inspection can be performed using a scanning charged particle microscope ("SCPM"). An example of an SCPM can be a scanning electron microscope (SEM). SCPM can be used to image these very small structures, in fact, to obtain an "image" of the structure of the wafer. The image can be used to determine whether the structure shown is properly formed and in the right place. If the structure is defective, the process can be adjusted so the defect is less likely to recur.

[0030] The working principle of SEM is similar to that of a camera. A camera takes an image by receiving and recording the intensity of light reflected or emitted from a person or object. SEM takes an "image" by receiving and recording the energy or amount of electrons reflected or emitted from the structure of the wafer. Before taking such an "image", an electron beam can be projected onto the structure, and when electrons are reflected or emitted ("emitted") from the structure (e.g., from the surface of the wafer, from the structure below the surface of the wafer, or both), the detector of the SEM can receive and record the energy or amount of those electrons to produce an inspection image. To obtain such an "image", the electron beam can be scanned across the wafer (e.g., in a row-by-row, zigzag, or serpentine manner) to form a primary beam spot at each location on the wafer. The detector can receive the emitted electrons from the area (primary beam spot) under the projection of the electron beam, which can form a secondary beam spot on the detector surface. The detector can receive and record the emitted electrons from each secondary beam spot one at a time and combine the information recorded for all beam spots to produce an inspection image. Some SEMs use a single electron beam (referred to as "single beam SEMs") to take a single "image" to produce an inspection image, while some SEMs use multiple electron beams (referred to as "multi-beam SEMs") to, for example, take multiple "sub-images" of a wafer in parallel, where these sub-images can be detected individually or collectively when stitched together. By using multiple electron beams, the SEM can provide more electron beams to the structure to obtain these multiple "sub-images", thereby causing more electrons to be ejected from the structure. Therefore, the detector can receive more ejected electrons at the same time and produce an inspection image of the structure of the wafer with higher efficiency and faster speed.

[0031] The ejected electrons received by the detector of the SEM can cause the detector to generate an electrical signal (e.g., a current, charge, or voltage signal) commensurate with the energy of the ejected electrons and the intensity of the electron beam. For example, the amplitude of the electrical signal can be commensurate with the intensity of the secondary beam spot formed on the detector by the ejected electrons. The detector can output the electrical signal to an image processor, and the image processor can process the electrical signal to form an image of the structure of the wafer. A multi-beam SEM system uses multiple electron beams for inspection, and the detector of the multi-beam SEM system can have multiple sections for receiving the electron beams. Each section can have multiple sensing elements and can be used to form an "image" of a sub-area of ​​the wafer. The "image" generated based on the signal from each section of the detector can be merged, for example, by a software program process to form a complete image of the inspected wafer.

[0032] It may be desirable to provide a detector architecture that can be optimized for different operating modes. For example, it may be desirable to optimize the detector for enhanced signal processing speed during one mode, while it may be preferred to optimize the detector for greater resolution in another operating mode.

[0033] For example, there may be a first mode called "image mode" that is used to associate a portion of the detector surface with a particular beam spot. The detector may include a pixelated array of many small sensing elements. When an electron beam spot is detected, these sensing elements may be connected to each other in groups through a switching network to form a combined signal. However, when the sensing elements are grouped together, it is impossible to know exactly which sensing element any portion of the signal comes from. Therefore, each connected group may include only those elements that are expected to receive the same beam spot. Image mode is a process for determining the shape and location of each beam spot on the detector surface in order to know which sensing elements should be grouped with each other during the normal inspection process (called "beam mode"). During image mode, high resolution is more important than processing speed.

[0034] In image mode, the output of each sensing element of the pixelated array can be read individually to determine each location on the detector surface that receives part of the beam spot. An image (e.g., a secondary electron beam projection image) representing a fine-grained projection pattern of the secondary beam spot on the detector surface can be formed. That is, a fine-grained image of the entire detector surface is produced. Based on this image, the boundaries of each beam spot can be determined, and a group of sensing elements can be selected so that the dividing line of the group is close to the boundary of the beam spot so that the electrons of the beam land on the sensing elements of the group. This selected group of sensing elements can be used later to detect the beam spot during beam mode. Image mode resolution can refer to the minimum size of a sensing element when operating in image mode.

[0035] In "beam mode", for example during an inspection process, sensing elements located within a determined dividing line can be grouped together and their outputs can be combined with each other to obtain the intensity of a secondary beam spot associated with the dividing line. Therefore, image mode may be suitable for determining the dividing line, and in beam mode during the inspection process, the desired grouping of sensing elements within the dividing line can be used. The switch matrix for interconnecting the sensing elements may include circuit systems, such as logic components, switches, and wiring paths between the sensing elements and readout circuits of the detector. During beam mode, processing speed may be more important than high resolution. Due to "parasitic" effects, processing speed can be reduced due to the number of circuit components electrically connected to the system during detection and the manner in which they are connected. The more sensing elements, switches, etc. connected to a group during detection, the worse the parasitic effects become.

[0036] Similar to image mode resolution, beam mode resolution may refer to the minimum size of a sensing element when operating in beam mode. In conventional systems, the minimum size of a sensing element is fixed and therefore the same in both image and beam mode. Thus, in conventional systems, image mode resolution and beam mode resolution may be equal. However, it may be desirable to select tradeoffs among detector parameters, such as trading lower speed for higher resolution, and vice versa, depending on the mode in which the detector operates.

[0037] Embodiments of the present disclosure provide a means to achieve this goal. Each sensing element is structured so that it can decompose itself into a smaller array of sub-sensing elements during image mode to obtain higher resolution, but it can operate as a single sensing element during beam mode to obtain better processing speed. The design of this sensing element is such that the circuit components for each sub-sensing element add very little or no parasitic effects when operating as a larger sensing element in beam mode. Therefore, high processing speed is maintained during beam mode.

[0038] For the sake of clarity, the relative sizes of the components in the drawings may be exaggerated. Within the following description of the figures, the same or similar reference signs refer to the same or similar components or entities, and only the differences with respect to individual embodiments are described.

[0039] The objects and advantages of the present disclosure can be achieved by the components and combinations described in the embodiments discussed in the present disclosure. However, it is not necessary for the embodiments of the present disclosure to achieve such exemplary objects or advantages, and some embodiments may not achieve any of the stated objects or advantages.

[0040] As used herein, unless specifically stated otherwise, the term "or" encompasses all possible combinations unless not feasible. For example, if it is stated that a component may include A or B, then unless specifically stated otherwise or not feasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component may include A, B, or C, then unless specifically 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.

[0041] Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure is illustrated. The EBI system 100 may be used for imaging. Figure 1As 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 load port 106a and a second load port 106b. The EFEM 106 may include additional load ports. The first load port 106a and the second load port 106b receive a wafer front opening transport box (FOUP) including wafers to be inspected (e.g., semiconductor wafers or wafers made of other materials) or samples to be inspected (wafers and samples can be used interchangeably). A "batch" is a plurality of wafers that can be loaded to be processed as a batch.

[0042] One or more robotic arms (not shown) of the EFEM 106 may transport the wafer to the load / lock chamber 102. The load / lock chamber 102 is connected to a load / lock vacuum pump system (not shown) that 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 robotic arms (not shown) may transport 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) that removes gas molecules in the main chamber 101 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subjected to inspection by the beam tool 104. The beam tool 104 may be a single beam system or a multi-beam system.

[0043] The controller 109 is electrically connected to the beam tool 104. The controller 109 may be a computer configured to perform various controls on the EBI system 100. Figure 1 1 as being external to the structure including the main chamber 101, the load / lock chamber 102, and the EFEM 106, but it should be understood that the controller 109 may be part of the structure.

[0044] In some embodiments, the controller 109 may include one or more processors (not shown). The processor may be a general or special electronic device capable of manipulating or processing information. For example, the processor may include any number of central processing units (or "CPUs"), graphics processing units (or "GPUs"), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general array logic (GALs), composite programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), system chips (SoCs), application specific integrated circuits (ASICs), and any combination of any type of circuits with data processing capabilities. The processor may also be a virtual processor, which includes one or more processors distributed on multiple machines or devices coupled via a network.

[0045] In some embodiments, the controller 109 may also include one or more memories (not shown). The memory may be a general or special electronic device capable of storing program codes and data that can be accessed by a processor (e.g., via a bus). For example, the memory may include any number of random access memories (RAM), read-only memories (ROM), optical disks, magnetic disks, hard disks, solid-state drives, flash drives, secure digital (SD) cards, memory sticks, compact flash (CF) cards, or any combination of any type of storage device. The program code and data may include an operating system (OS) and one or more application programs (or "apps") for a specific task. The memory may also be a virtual memory, which includes one or more memories distributed on multiple machines or devices coupled via a network.

[0046] Figure 2 1 and 2. An exemplary multi-beam tool 104 (also referred to herein as device 104) and an exemplary multi-beam tool 104 (also referred to herein as device 104) consistent with embodiments of the present disclosure and that may be configured for use with an EBI system 100 ( Figure 1 ) in Figure 290 of image processing system 290.

[0047] The beam tool 104 includes: a charged particle source 202, a gun aperture device 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 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.

[0048] Charged particle source 202, aperture device 204, focusing lens 206, source conversion unit 212, beam splitter 222, deflection scanning unit 226, and objective lens 228 may be aligned with primary optical axis 260 of device 104. Secondary optical system 242 and charged particle detection device 244 may be aligned with secondary optical axis 252 of device 104.

[0049] The charged particle source 202 may emit one or more charged particles, such as electrons, protons, ions, protons, 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 extraction device, 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 a crossover point (virtual or real) 208. For ease of explanation and without causing disagreement, electrons are used as examples in some of the descriptions of the present disclosure. However, it should be noted that any charged particles may be used in any embodiment of the present disclosure, without being limited to electrons. The primary charged particle beam 210 may be visualized as being emitted from the crossover point 208. The gun hole device 204 may block the peripheral charged particles of the primary charged particle beam 210 to reduce the Coulomb effect. The Coulomb effect may cause an increase in the size of the detection spot.

[0050] 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 (virtual or real) images of the crossover point 208 using the multiple beam waves 214, 216, and 218 of the primary charged particle beam 210. The beam limiting aperture array may limit the multiple beam waves 214, 216, and 218. Although in Figure 2 , three beams 214, 216, and 218 are shown, but the embodiments of the present disclosure are not limited thereto. For example, in some embodiments, the device 104 may be configured to generate a first number of beams. In some embodiments, the first number of beams may be in the range of 1 to 1000. In some embodiments, the second number of beams may be in the range of 200 to 500. In an exemplary embodiment, the device 104 may generate 400 beams.

[0051] The condensing lens 206 can focus the primary charged particle beam 210. The currents of the beams 214, 216, and 218 downstream of the source conversion unit 212 can be varied by adjusting the focusing magnification of the condensing lens 206 or by changing the radial size of the corresponding beam limiting apertures in the beam limiting aperture array. The objective lens 228 can focus the beams 214, 216, and 218 on the wafer 230 for imaging, and can form a plurality of detection spots 270, 272, and 274 on the surface of the wafer 230.

[0052] The beam splitter 222 may be a Wien filter type beam splitter that generates an electrostatic dipole field and a magnetic dipole field. In some embodiments, if the electrostatic dipole field and the magnetic dipole field are applied, the force exerted on the charged particles (e.g., electrons) of the beam waves 214, 216, and 218 by the electrostatic dipole field may be equal in magnitude and opposite in direction to the force exerted on the charged particles by the magnetic dipole field. The beam waves 214, 216, and 218 may therefore pass directly through the beam splitter 222 at a zero deflection angle. However, the total dispersion of the beam waves 214, 216, and 218 generated by the beam splitter 222 may also be non-zero. The beam splitter 222 may separate the secondary charged particle beams 236, 238, and 240 from the beam waves 214, 216, and 218, and direct the secondary charged particle beams 236, 238, and 240 toward the secondary optical system 242.

[0053] The deflection scanning unit 226 can deflect the beams 214, 216, and 218 to scan the detection spots 270, 272, and 274 over the surface area of ​​the wafer 230. In response to the beams 214, 216, and 218 being incident on the detection spots 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 beams 214, 216, and 218). The secondary optical system 242 can focus the secondary charged particle beams 236, 238, and 240 onto detection sub-areas 246, 248, and 250 of the charged particle detection device 244. The detection sub-areas 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 a scanning charged particle microscope (SCPM) image of a structure on or below the surface area of ​​the wafer 230.

[0054] 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 spots (e.g., scanning detection spots 270, 272, and 274) may orderly cover the area of ​​interest on the wafer 230. These synchronization and coordination parameters may be adjusted to accommodate different materials of the wafer 230. For example, wafers 230 of different materials may have different resistance-capacitance characteristics, which may cause different signal sensitivities to the movement of the scanning detection spots.

[0055] 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 includes a defect. In addition, as discussed above, the beams 214, 216, and 218 may be projected onto different portions of the top surface of the wafer 230 or onto different sides of the local structure of the wafer 230 to generate the secondary charged particle beams 236, 238, and 240 that may have different intensities. Thus, by mapping the intensities of the secondary charged particle beams 236, 238, and 240 using regions of the wafer 230, the image processing system 290 may reconstruct an image reflecting the characteristics of the internal or external structure of the wafer 230.

[0056] In some embodiments, the image processing system 290 may include an image acquisition device 292, a storage device 294, and a controller 296. The image acquisition device 292 may include one or more processors. For example, the image acquisition device 292 may include a computer, a server, a mainframe computer, a terminal, a personal computer, any type of mobile computing device, or the like, or a combination thereof. The image acquisition device 292 may be communicatively coupled to the charged particle detection device 244 of the beam tool 104 by a medium such as an electrical conductor, an optical fiber cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, radio, or a combination thereof. In some embodiments, the image acquisition device 292 may receive a signal from the charged particle detection device 244 and may construct an image. The image acquisition device 292 may thus acquire an SCPM image of the wafer 230. The image acquisition device 292 may also perform various post-processing functions, such as generating a contour, superimposing an indicator on the acquired image, and the like. The image acquisition device 292 may be configured to perform adjustments to the brightness and contrast of the acquired image. In some embodiments, the storage 294 may be a storage medium such as a hard disk, a flash memory drive, a cloud storage, a random access memory (RAM), other types of computer readable memory, etc. The storage 294 may be coupled to the image acquirer 292 and may be used to save the scanned raw image data as an initial image and to save a post-processed image. The image acquirer 292 and the storage 294 may be connected to a controller 296. In some embodiments, the image acquirer 292, the storage 294, and the controller 296 may be integrated together into a control unit.

[0057] 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 image signal may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image including a plurality of imaging regions. The single image may be stored in the storage 294. The single image may be an original image that may be divided into a plurality of zones. Each of the zones may include an imaging region containing features of the wafer 230. The acquired image may include a plurality of images of a single imaging region of the wafer 230 sampled multiple times within a time sequence. The plurality of images may be stored in the storage 294. In some embodiments, the image processing system 290 may be configured to perform image processing steps on a plurality of images of the same portion of the wafer 230.

[0058] 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 combined with the corresponding scan path data of the beams 214, 216, and 218 incident on the wafer surface can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the internal or external structure of the wafer 230, and thus can be used to reveal any defects that may be present in the wafer.

[0059] 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., the detection spots 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, thereby interacting with the particles of the wafer 230. Some electrons of the primary charged particle beam 210 may elastically interact with the material of the wafer 230 (e.g., in the form of elastic scattering or collision), and may be reflected or recoiled out of the surface of the wafer 230. Elastic interactions preserve 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 energy forms (e.g., thermal energy, electromagnetic energy, etc.). Such reflected electrons generated from elastic interactions may be referred to as backscattered electrons (BSE). Some electrons in the primary charged particle beam 210 may inelastically interact with the material of the wafer 230 (e.g., in the form of inelastic scattering or collision). Inelastic interactions do not preserve the total kinetic energy of the interacting subject, wherein some or all of the kinetic energy of the interacting subject is converted into other forms of energy. For example, via inelastic interactions, the kinetic energy of some of the electrons in the primary charged particle beam 210 may cause electron excitation and transitions of atoms of the material. Such inelastic interactions may also generate electrons that are ejected from the surface of the wafer 230, which may be referred to as secondary electrons (SEs). The yield or emission rate of BSEs and SEs depends, for example, on the material being inspected and the landing energy of the electrons of the primary charged particle beam 210 landing on the surface of the material. The energy of the electrons of the primary charged particle beam 210 may be partially determined by its accelerating voltage (e.g., in Figure 2 The number of BSEs and SEs may be more or less (or even the same) than the injected electrons of the primary charged particle beam 210.

[0060] The images generated by the beam tool 104 can be used for defect inspection. For example, the generated image capturing the test device area of ​​the 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 include 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 beam tool 104 can scan multiple areas of the wafer, each area including test device areas designed to be the same, and generate multiple images capturing those 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.

[0061] Figure 3A FIG. 3 is an exemplary structure of a detector 300A consistent with an embodiment of the present disclosure. The detector 300A may be provided as Figure 2 An example of a charged particle detection device 244 is shown in FIG. Figure 3A In the embodiment, the detector 300A includes a sensor layer 301, a segment layer 302, and a readout layer 303. The sensor layer 301 may include a sensor die composed of a plurality of sensing elements, including sensing elements 311, 312, 313, and 314. In some embodiments, the plurality of sensing elements may be arranged in an array of sensing elements in which each sensing element may have a uniform size, shape, and arrangement. The detector 300A may have an arrangement relative to a coordinate axis reference coordinate system. The sensor layer 301 may be arranged along an xy plane. The sensing elements in the sensor layer 301 may be arranged in the x-axis and y-axis directions. The x-axis direction may also be referred to herein as a "first lateral" direction. The y-axis direction may also be referred to herein as a "second lateral" direction. The detector 300A may have a layer structure in which the sensor layer 301, the segment layer 302, and the readout layer 303 are stacked in the z-axis direction. The z-axis direction may also be referred to herein as a "thickness" direction (e.g., a direction parallel to the thickness of the substrate on which the detector is formed). The z-axis direction may be aligned with an incident direction of charged particles directed toward the detector 300A.

[0062] Segment layer 302 may include multiple segments, including segments 321, 322, 323, and 324. The segments may include interconnects (e.g., wiring paths) configured to communicatively couple multiple sensing elements. The segments may also include switches that may control communicatively coupling between the sensing elements. The segments may also include connection mechanisms (e.g., wiring paths and switches) between the sensing elements and one or more common nodes of the segment layer. For example, Figure 3AAs shown, segment 323 can be configured to be communicatively coupled to the output ends of sensing elements 311, 312, 313, and 314, as shown by the four dotted lines between sensor layer 301 and segment layer 302. In some embodiments, segment 323 can be configured to output a combined signal collected from sensing elements 311, 312, 313, and 314 as a common output. In some embodiments, a segment (e.g., segment 323) can be communicatively coupled to a sensing element (e.g., sensing elements 311, 312, 313, and 314) arranged directly above the segment. For example, segment 323 can have a grid of terminals configured to be connected to the output ends of sensing elements 311, 312, 313, and 314. In some embodiments, segments 321, 322, 323, and 324 can be arranged in an array structure so that they have uniform size and shape and uniform arrangement. For example, segments 321, 322, 323, and 324 can be square. In some embodiments, isolation regions may be provided between adjacent segments to electrically insulate adjacent segments from each other. In some embodiments, the segments may be arranged in an offset pattern such as a tiled layout.

[0063] The 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 of the segments of the segment layer 302. In some embodiments, a plurality of separate signal processing circuitry segments may be provided, including signal processing circuitry segments 331, 332, 333, and 334. In some embodiments, the signal processing circuitry segments may be arranged in an array of segments having uniform size and shape and uniform arrangement. In some embodiments, the signal processing circuitry segments may be configured to connect to the outputs of the corresponding segments from the segment layer 302. For example, as Figure 3A As shown, the signal processing circuitry section 333 may be configured to be communicatively coupled to the output of the section 323 , as shown by the dashed line between the section layer 302 and the readout layer 303 .

[0064] In some embodiments, the readout layer 303 may include input terminals and output terminals. One or more output terminals of the readout layer 303 may be connected to components for reading and interpreting the output of the detector 300A. For example, the readout layer 303 may be directly connected to a digital multiplexer, a digital logic block, a controller, a computer, etc.

[0065] The size of the segments and the number of sensing elements associated with the segments can vary. Figure 3A A 2×2 array of four sensing elements in one section is illustrated, but embodiments of the present disclosure are not limited thereto. A section may include, for example, an array of 3×3, 4×4, 1×6, or any desired number of sensing elements.

[0066] Although Figure 3A The sensor layer 301, the segment layer 302, and the readout layer 303 are illustrated as multiple discrete layers, but it should be noted that the sensor layer 301, the segment layer 302, and the readout layer 303 do not have to be provided as separate substrates or tube cores. For example, the wiring paths of the segment layer 302 can be provided in the sensor tube core that includes multiple sensing elements, or can be provided outside the sensor tube core. The wiring paths can be patterned on the sensor layer 301. In addition, the segment layer 302 can be combined with the readout layer 303. For example, a semiconductor tube core including the wiring paths of the segment layer 302 and the signal processing circuit of the readout layer 303 can be provided. Therefore, the structure and functionality of the various layers can be combined or divided.

[0067] 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 segment layer, and the readout layer may be implemented in one die or in a package that may include one or more dies.

[0068] In some embodiments, the arrangement of the sensor layer 301, the segment layer 302, and the readout layer 303 may correspond to each other in a stacked relationship. For example, the segment layer 302 may be mounted directly on top of the readout layer 303, and the sensor layer 301 may be mounted directly on top of the segment layer 302. The layers may be stacked so that the segments within the segment layer 302 are aligned with the signal processing circuitry segments (e.g., segments 331, 332, 333, and 334) of the readout layer 303. In addition, the layers may be stacked so that one or more sensing elements within the sensor layer 301 are aligned with the segments in the segment layer 302. In some embodiments, the sensing elements to be associated with the segments may be contained within the segments. For example, in a plan view of the detector 300A, the sensing elements (e.g., sensing elements 311, 312, 313, and 314) of the segments (e.g., segment 323) may be assembled within the demarcation lines of the segments. Furthermore, individual segments of the segment layer 302 may be overlaid with signal processing circuitry segments of the readout layer 303. In this manner, predefined areas for associating sensing elements with segments and signal processing circuitry may be established.

[0069] Figure 3B is a diagram illustrating an exemplary detector array 300B with switches consistent with an embodiment of the present disclosure. The detector array 300B may be Figure 3A 300A in the detector array. For example, the detector array 300B may include a sensor layer (e.g., similar to Figure 3A Sensor layer 301 in ), segment layer (e.g., similar to Figure 3A) and a readout layer (e.g., similar to Figure 3A The sensor layer of the detector array 300B may include a plurality of sensing elements 315. In some embodiments, each of the sensing elements 315 of the detector array 300B may have a uniform size, shape, and arrangement. The sensing elements of the detector array 300B may generate a current signal commensurate with charged particles (e.g., ejected electrons) received in an active region of the sensing element. An "active region" may refer herein to a region of a sensing element having a radiation sensitivity above a predetermined threshold.

[0070] The segment layer of the detector array 300B may include a base substrate (eg, a semiconductor substrate, Figure 3B ), the base substrate includes one or more wiring paths 342. The wiring paths 342 can be configured to communicatively couple the sensing elements of the detector array 300B. Figure 3B As shown, detector array 300B includes a segment 325 having a 4×4 array of sensing elements 315. The 4×4 array of segment 325 may have Figure 3A A similar architecture is used for the 2×2 array in any one of the sections 321 to 324. Figure 3B , the segment layer of the detector array 300B may include an inter-element switch 340 between any two adjacent sensing elements 315. The segment layer of the detector array 300B may also include an inter-element switch 340 that is communicatively coupled to adjacent sensing elements on the edge of an adjacent segment. The wiring pathways 342 may be configured to be communicatively coupled to the output ends of the sensing elements 315 in the segment 325. For example, the wiring pathways 342 may have a grid of terminals (shown as circular black dots at the center of the sensing elements) that are configured to connect to the output ends of the sensing elements 315. In some embodiments, the wiring pathways 342 may be disposed in the segment layer of the detector array 300B. Figure 3B In FIG. 3 , the wiring path 342 is communicatively coupled to the above sensing element 315. Figure 3B In the embodiment of the present invention, the element-bus switch 341 can be disposed between the output terminal of the sensing element and the wiring path 342. In some embodiments, the element-bus switch can be disposed in the segment layer of the detector array 300B.

[0071] In some embodiments, the wiring paths 342 may include lines of conductive material printed on a base substrate, flexible lines, wiring, etc. In some embodiments, switches may be provided so that the outputs of individual sensing elements may be connected or disconnected from the common output of the segments 325. In some embodiments, the segment layers of the detector array 300B may also include corresponding circuits for controlling the switches. In some embodiments, the switches may be arranged in a separate switch-element matrix that may itself include circuits for controlling the switches.

[0072] The readout layer of the detector array 300B 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 344 and one or more analog switches ( Figure 3B (not shown). Amplifier 344 may be a high-speed transimpedance amplifier, a current amplifier, etc. Figure 3B In the embodiment, amplifier 344 can be communicatively coupled to the common output terminal of segment 325 for amplifying the output signal of the sensing element of segment 325. In some embodiments, amplifier 344 can be a single-stage or multi-stage amplifier. For example, if amplifier 344 is a multi-stage amplifier, it can include a preamplifier and a post-amplifier, or include a front-end stage and a post-stage, etc. In some embodiments, amplifier 344 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 the signal path, which can include, for example, an analog-to-digital converter (ADC) 346. In the embodiment, amplifier 344 can be a variable gain amplifier, such as a variable gain transimpedance amplifier (VGTIA), a variable gain charge transfer amplifier (VGCTA), etc. Figure 3B 346 can be communicatively coupled to the output of a conditioning circuit (e.g., including amplifier 344) to convert the analog output signals of the sensing elements of segment 325 into digital signals. The readout layer of detector array 300B can also include other circuits for other functions. For example, the readout layer of detector array 300B can include switch-element actuation circuits that can control switches between sensing elements. For ease of explanation and without ambiguity, the signal path between the sensing elements and ADC 346 can be referred to as an "analog signal path." For example, Figure 3B The analog signal path in includes the signal conditioning circuit described above (eg, including amplifier 344 ). An input of the analog signal path is communicatively coupled to the sensing element, and an output of the analog signal path is communicatively coupled to ADC 346 .

[0073] In some embodiments, ADC 346 may include an output terminal communicatively coupled to a component (eg, a component within or outside the readout layer of detector array 300B) for reading and interpreting the digital signal converted by ADC 346. Figure 3B In the embodiment of the present invention, ADC 346 is communicatively coupled to digital multiplexer 348. In some embodiments, digital multiplexer 348 can be arranged in the readout layer of detector array 300B. Digital multiplexer 348 can receive multiple input signals and convert them into output signals. The output signal of digital multiplexer 348 can be converted back into multiple input signals. The output signal of digital multiplexer 348 can also be transmitted to a data processing stage (e.g., Figure 2 The image processing system 290 in FIG. 2 can be found in previously incorporated International Publication No. WO 2021 / 239754 A1 and International Publication No. WO 2021 / 219519 A1. FIG. 3A to FIG. 3B For further details of the detector arrangements, the entire contents of these international publications are incorporated herein by reference.

[0074] FIG. 4A to FIG. 4B Surface and image mode operations of the detector 400 according to a comparative embodiment are illustrated. Figure 4A The surface of the detector 400 is shown. The detector 400 in this comparative embodiment may correspond to the detection surface of the charged particle detection device 244 or the detector 300A or 300B. The detection surface may include an array of sensing elements such as PIN diode elements. In some embodiments, the sensing element may include, for example, an avalanche diode, an electron multiplier tube (EMT), or other components. Each sensing element in the sensing element (e.g., a PIN diode) may correspond to a discrete sensing element 415. Alternatively, a single sensing element (e.g., a PIN diode) may be pixelated into a plurality of individual sensing elements 415 in various ways. For example, a semiconductor detection unit may be divided by means of an internal field generated due to an internal structure. In some embodiments, there may be a physical separation between adjacent sensing elements, such as by a region 408 disposed between adjacent sensing elements. Region 408 may be an isolation region to isolate the sides or corners of adjacent sensing elements from each other. In some embodiments, region 408 may include an insulating material different from the insulating material of the sensing element 415 on the sensor surface of the detector 400. In some embodiments, region 408 may be provided as a square. In some embodiments, region 408 may not be disposed between adjacent sides of the sensing element.

[0075] like Figure 4AAs shown, there may be a region of interest 405 on the surface of the detector 400. The pixelated array of sensing elements on the detector may constitute the region of interest 405. In some embodiments, there may be more sensing elements disposed in the detector outside of the region of interest 405. The region of interest 405 may be a portion of the detector.

[0076] Figure 4B FIG. 4 is a diagram showing an image mode operation according to a comparative embodiment. According to the comparative embodiment, the secondary beam spot 480 is formed at Figure 4A The beam spot 480 may be on the surface of the detector 400. The beam spot 480 may have a well-defined center or trajectory. Although the beam spot 480 is illustrated as having a generally circular shape, the distribution of secondary particles landing within the beam spot 480 may have an irregular shape and may generally deviate from the ideal circular shape. Some areas of the beam spot 480 may receive more secondary particles than other areas. Secondary particles may be generated in response to the incidence of the primary beam on the sample and may be emitted at a variety of energies and emission angles. The secondary particles may form a beam (e.g., a secondary electron beam). The secondary electron beam may be incident on the detector and may form a beam spot 480.

[0077] In addition, if Figure 4B As shown, a demarcation line 410 can be determined. The demarcation line 410 can be provided so as to cover the sensing elements that receive charged particles from the secondary electron beam. The sensing elements included in the demarcation line 410 can be at least partially covered by the same charged particle beam spot. The demarcation line 410 can include the boundary of the beam spot 480. As used in the present disclosure, the term "demarcation line" can refer to the outer periphery of the beam spot encoded with the detector. The shape of the demarcation line can conform to the shape of the individual sensing elements 415. "Boundary" can refer to the outline of the beam spot. The boundary of the beam spot may more closely correspond to the natural shape formed by the charged particles of the beam impacting on the surface. For example, the beam spot can have a generally circular boundary and a demarcation line that is closer to a square surrounding the boundary. In some embodiments, the boundary and the demarcation line can be consistent or coincident.

[0078] The beam spot demarcation line can be determined based on the acquired beam spot projection pattern. The beam spot projection pattern can be acquired by reading the individual outputs of the sensing elements that can be included in the detector. In the "image" mode, an image of the detector surface can be acquired and the demarcation line or grouping of the sensing elements associated with the beam spot can be determined. During the image mode, the detection system can be dedicated to the projection pattern acquisition. For example, it can be determined that electrons are being received in the sensing element group on the detector surface 400. The group of sensing elements can be continuous and can have a generally circular shape. The beam spot demarcation line 410 can be drawn around the sensing elements in the group. Each of the sensing elements within the demarcation line can receive electrons at least partially within the surface area of ​​the sensing element. The sensing elements included in the group can be used for subsequent processing, such as beam spot intensity determination (for example, using the "beam" mode). Other processing in the image mode may include pattern recognition, edge extraction, etc. In some embodiments, the beam spot 480 may deviate from a circular shape. For example, the beam spot 480 may have an elongated shape. As the beam spot 480 changes shape or drifts across the detector surface 400, a new boundary 410 corresponding to the new shape or location can be determined, and thus a new grouping of sensing elements associated with the beam spot 480 can be updated. However, since the detector cannot detect the spatial location of an electron landing event within any given sensing element 415, the minimum resolution of the beam spot boundary 410 is determined by the size of one sensing element 415.

[0079] After determining the demarcation line 410 for the beam spot in image mode, the sensing elements within the demarcation line can be grouped together in beam mode during normal operation such as an inspection process. The grouped elements can be functionally coupled so that the intensity measured at the grouped sensing elements within the demarcation line 410 is determined as a beam parameter, such as intensity, corresponding to the secondary beam spot 480. The grouping is determined in discrete sensing element units. Therefore, the image resolution of the detector in image mode (image mode resolution) is the same as the grouping resolution of the detector in beam mode (beam mode resolution). Additional details of image mode operation 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.

[0080] Figure 4C is a diagrammatic representation of a 4×4 segment of a sensing element 415 in a detector chip circuit design according to a comparative embodiment. The arrangement may correspond to FIG. 4A to FIG. 4B4×4 array of sensing elements 415 in the detector chip, wherein each sensing element circuit 416 corresponds to a unit cell including the sensing element 415 and associated switching elements and other circuit systems. Multiple sections having the same structure are repeated in the detector chip, and adjacent sections are interconnected with each other, as indicated by long arrows. A grouping switch 440 is arranged between every two adjacent sensing elements so that the detector chip can implement a grouping function in a beam mode. The switch may correspond to Figure 3B In addition, an element-bus switch 441 is arranged between each sensing element 415 and a common signal bus 442 to enable addressing of individual sensing elements in image mode. The signal bus 442 can be, for example, a wiring path 342, such as with respect to FIG. 3A to FIG. 3B Common signal bus 442 is further connected to adjacent pickup points of connection node 430 and other circuit sections, as described by Figure 4C As indicated by the short arrow at the bottom of . Connections to the connection node and adjacent pick-up points can be made by the section switch 443.

[0081] Between each sensing element 415 (e.g., a PIN diode) and a signal ground or common voltage 418, there may be a ground switch 444 configured to release charge from the sensing element circuit 416 when it is not in use. When the sensing element is not in use, the ground switch 444 may be closed so that there is no charge accumulation on the sensing element circuit 416 due to, for example, full or partial incidence of the secondary electron beam spot on the sensing element. Such charge accumulation may cause detector malfunction or damage. When the switch is "closed", both sides of the switch are electrically connected, and when the switch is "open", the two sides of the switch are isolated from each other.

[0082] When the detector is operated in imaging mode, a charged particle beam (e.g., a secondary electron beam) may irradiate multiple sensing elements. In order to determine which sensing elements are being irradiated by the beam, each element-bus switch 441 on the common signal bus 442 may be closed one at a time. During a given time period, there may be only one sensing element coupled to each readout signal path. In this way, the signal output reaching the signal processing circuit during the time period may be uniquely identified as belonging to a particular sensing element. By sequentially coupling and decoupling each sensing element in a segment of the detector to the common signal bus 442 of the segment, detection information about each sensing element 415 may be obtained. Thus, the detector may be controlled (e.g., by the controller 109 or the image processing system 290) to determine the spatial distribution of the sensing elements 415 that are incident on the beam spot 480, and use the spatial distribution to construct the dividing line 410, such as Figure 4BAs seen in . Although each individual readout path can only read one sensing element at a time, the detector in image mode can still read out multiple sensing elements in parallel by using multiple signal readout paths to speed up the image capture process. In addition, pixel merging can be performed. Pixel merging can involve combining signals from more than one sensing element when transmitting the signal to the output bus. Pixel merging can be suitable for obtaining images with relatively low resolution of secondary beam projection patterns at relatively high speeds. Pixel merging can include using switches between the sensing elements and the bus to connect more than one sensing element to the bus at a time. Pixel merging can include using inter-element switching elements to connect the sensing elements to be merged together. Then, any of the element-bus switching elements connected to the merged sensing element can be actuated to connect the merged sensing element to the bus. Sensing elements can be merged in any shape or number during image mode operation.

[0083] In theory, using ideal switch and sense elements, Figure 4C The circuit design can achieve greater configuration flexibility without performance penalty. For example, the same repeated circuit design can be greatly reduced in size and can be multiplied to achieve higher resolution without any degradation of other performance parameters. However, real analog switches and sensing elements are subject to parasitic parameters. For example, the speed or analog bandwidth of the system may be reduced due to, for example, parasitic capacitance. For this reason, additional segment switches 443 can be added between the common signal bus 442 and the connection node 430, where the connection node leads to the input of the pickup point and readout circuit system in each segment. The purpose of this switch is to isolate the parasitic capacitance from the sensing element and its corresponding image mode switch that are not used when the detector 400 operates in the beam mode, so that the analog bandwidth can be improved. However, if the size of the sensing element 415 is reduced to increase the sensing element density (with a corresponding improvement in resolution), the number of switches required for grouping purposes (e.g., switches 440 connecting adjacent sensing elements 415) will increase proportionally. Therefore, due to the increase in the number of switches and sensing elements, parasitic capacitance may increase. Furthermore, a higher total switch count may increase parasitic resistance (series resistance) due to a larger number of switches arranged in series. All of this may result in reduced analog bandwidth when the detector is operating in beam mode. This in turn may cause blurred SEM images compared to a detector with fewer circuit components at the same SEM pixel rate. Throughput may be reduced due to the lower available SEM pixel rate to avoid such blurring. Therefore, from the perspective of system throughput and analog bandwidth of the detection channel, the detection bandwidth of the detector is reduced in the beam mode. Figure 4C There are functional restrictions in the layout of the sensing element on the minimum allowed size.

[0084] However, it may be desirable to have a higher resolution image of the secondary electron beam spot, which may be suitable for SEM system tuning and image mode element grouping. A high resolution image may provide more information about the secondary electron beam spot on the detector surface. This may help improve SEM system tuning results and enable better element grouping decisions. Such a higher resolution may require that the sensing element size in image mode be smaller than Figure 4C The detector architecture can provide a sensing element size of .

[0085] Figure 5A The surface of a detector 500 consistent with an embodiment of the present disclosure that can address one or more of the above challenges is illustrated. The detector 500 can be a detection surface of a charged particle detection device 244 or a detector 300A or 300B. The detector 500 can include an array of sensing elements 515. When viewing the system at a level greater than the level of the sensing elements, FIG. 5A to FIG. 5C The overall switch matrix design and circuit design in can be presented as similar to FIG. 4A to FIG. 4C However, inspection at the level of a single sensing element 515 reveals a different architecture. FIG. 4A to FIG. 4C In the comparative embodiment of FIG. 4 , the sensing element 415 is the smallest unit pixel size that can be detected on the detector 400. In the embodiment of the present disclosure, in FIG. 5A to FIG. 5C At , a sub-sensing element 520 is introduced into each sensing element 515 for resolution enhancement in image mode. The new design has almost no impact on the analog bandwidth in beam mode. This helps eliminate the need to compromise between the secondary electron projection image resolution in image mode and the analog bandwidth or SEM image pixel rate in beam mode. In some embodiments, as discussed further below, the new design can also provide additional resolution capabilities in beam mode.

[0086] like Figure 5A As seen in , the detector 500 may include an array of sensing elements 515, wherein the sensing elements may be further divided into sub-sensing elements 520. For example, the sensing element 515 may include a 4×4 grid array of sub-sensing elements 520. In practice, any arrangement of the sub-sensing elements is possible. For example, there may be more or fewer sub-sensing elements, and they need not be arranged in a square or even rectangular array. In some embodiments, the array of sub-sensing elements 520 may occupy substantially the entire area of ​​the element 515 between the isolation regions 508. In some embodiments, the regions 508 may not be disposed between adjacent sides of the sensing element 515. Each sub-sensing element 520 within the sensing element 515 may be individually addressed, as further described below.

[0087] Figure 5B The diagram is formed in Figure 5AA secondary beam spot 580 on the surface of the detector 500 consistent with an embodiment of the present disclosure. The secondary beam spot 580 may be similar to Figure 4B However, since the detector 500 includes an array of sub-sensing elements 520 that can be individually addressed, the boundary 510 can be determined for the secondary beam spot 580 with a much higher resolution than the boundary 410 around the secondary beam spot 480. During image mode operation, each sub-sensing element 520 within the sensing element 515 can be individually addressed to detect whether an electron landing event has occurred at a precise location of the sub-sensing element. The boundary 510 can then be determined with a higher degree of accuracy at the resolution level of the sub-sensing element 520. Figure 5B The upper right portion of FIG. 5 shows the difference more clearly in a close-up of a 3×3 section of sense element 515 that includes sub-sense element 520 .

[0088] The demarcation line 510 obtained with higher accuracy using the sub-sensing elements 520 can be used to determine the appropriate grouping of the sensing elements 515 during the beam mode. In some embodiments of the present disclosure, it can also be used to determine the partial sensing elements for grouping in the beam mode. For example (as described below with respect to Figure 6C As discussed above, sensing elements 515 on the perimeter of a group of sensing elements may activate only a portion of their sub-sensing elements 520 during beam mode in order to more closely follow the shape of beam spot 580.

[0089] Figure 5C is a diagrammatic representation of a sub-sensing element detector architecture consistent with an embodiment of the present disclosure. Sensing element 515 may correspond to, for example, Figure 3A The sensing elements 311 to 314 in Figure 3B The sensing element 315 in or FIG. 4A to FIG. 4B The sensing element 415 in the detector chip circuit design may form part of a detector such as detector 300A, 300B or 500. The sensing element circuit 516 may include a similar Figure 4CSome features of the sense element circuit 416. For example, the sense element circuit 516 and associated circuit system may include: a grouping switch 540, which is located between adjacent sense elements for grouping adjacent sense elements in beam mode; an element-bus switch 541, which is used to connect to the signal bus 542 to enable individual sense element addressing in image mode; a segment switch (not shown), which is located between the common signal bus 542 and the connection node, which leads to the pickup point and the input of the readout circuit system in each segment; and a ground switch 544, which is located between each sense element and the signal ground or common voltage 518, and is configured to release charge from the sense element circuit 516 when the sense element circuit 516 is not in use. However, unlike Figure 4B The sensing element 415 may be subdivided into an array of smaller sub-sensing elements 520. The sub-sensing elements 520 may be, for example, PIN diodes or any other suitable sub-sensing elements that can convert charged particle landing events into measurable signals. The charged particle landing events may reflect information such as the energy of the incident charged particle, the timestamp of the landing, the number of charged particles that landed in a period of time, or any information indicating the nature of the charged particles that landed on the detector. In addition, as Figure 5C As shown in the close-up in FIG. 5 , each sub-sense element 520 can be coupled to a sub-element switch 522 on a first side and a sense element node 523 on a second side. As shown, the sub-element switch 522 is located on the bias side of the sub-sense element 520. However, the switch can be located on the signal side instead.

[0090] When the detector is operated in image mode, each sensing element 515 can be individually selected by connecting and disconnecting each sensing element 515 to the common signal bus 542 in sequence via the element-bus switch 541 of the sensing element 515. However, while the sensing element 515 is selected, each of its sub-sensing elements 520 can also be individually addressed. By closing each sub-element switch 522 one at a time, only one sub-sensing element 520 will be connected to provide a signal output. The signal output can correspond to a single sub-pixel in a high-resolution image and can be referred to as an image mode sub-pixel signal. A controller (e.g., controller 109 or image processing system 290) can electronically scan the entire detector using a combination of segment horizontal addressing switches (e.g., connecting each sensing element 515 in sequence) and sensing element horizontal address switches (e.g., connecting each sub-sensing element 520 within a sensing element 515 in sequence). Therefore, a high-resolution secondary electron beam spot image can be captured on the detector surface. The detector 500 can be configured so that it can still read out multiple sensing elements in parallel in image mode, just as existing detectors can do when multiple readout signal paths are used to speed up the image capture process. However, within the segment connected to one readout signal path, since all sub-sensing elements 520 within the sensing element 515 share a common sensing element node 523, improved resolution can be achieved by addressing one sub-sensing element 520 at a time via the sub-element switch 522 corresponding to the sub-sensing element 520. Although individual addressing of sub-sensing elements may require more time than a comparative embodiment without sub-sensing elements, higher resolution images may outweigh this and other concerns. Speed ​​may be more important during beam mode operation, as discussed below. High-resolution imaging can be beneficial for SEM tuning and alignment, as well as for sensing element grouping.

[0091] In addition, the same method as described above for the comparative example can be used. Figure 4C Subpixel binning is performed in a similar manner to the pixel binning discussed. For example, to increase readout speed in exchange for a corresponding lower resolution, more than one sub-sensing element 520 may be addressed at one time within a single sensing element 515. The sub-sensing elements 520 may be binned in any shape, and they need not be immediately adjacent to each other.

[0092] FIG. 6A to FIG. 6B An example of a 4×4 segment of sensing elements in a detector chip circuit design consistent with an embodiment of the present disclosure is shown. Sensing element 615 is shown in Fig. 6A , and the sensing element circuit 616 is shown in the dashed box in the upper right corner. The sensing element 615 may correspond to, for example, Figure 3A The sensing elements 311 to 314 in Figure 3B The sensing element 315 in FIG. 5A to FIG. 5B 5. The sensing element circuit 616 may be a unit cell including the sensing element 615 and associated switching elements and other circuitry. A plurality of sensing element circuits 616 are provided as repeated unit cells. The detector chip circuit design may form part of a detector such as detector 300A, 300B or 500.

[0093] Fig. 6A 4×4 segments during image mode operation are shown. At the moment depicted in the figure, only the upper leftmost sensing element circuit 616 communicates with the signal path by means of the closed element-bus switch 641 and the segment switch 643. In addition, within the sensing element circuit, as shown in the dotted box 624, there may be only one sub-sensing element 620, which communicates with the signal path by closing the sub-element switch 622 corresponding to the sub-sensing element 620. If a portion of the secondary electron beam is incident on a portion of a connected sensing element 620, the signal can be communicated to the signal processing circuit of the detector. The signal can indicate that the portion is being irradiated by the secondary electron beam (for example, including by comparing the signal with a threshold, by applying filtering to eliminate, for example, noise or dark current). By scanning each sub-sensing element 620 of each sensing element 615, a high-resolution image can be obtained. The image can be applied to a sensing element grouping algorithm, for SEM tuning / alignment, or otherwise used to enhance the operation of a charged particle beam device. It should be noted that in some embodiments, other switches can be opened or closed. For example, unused sense element circuits 616 can have their ground switches 644 closed to avoid charge accumulation. Additionally, if multiple readout paths are available, other sense elements 616 can be connected to the ground switch 644. Fig. 6A The upper left sensing element circuit shown in FIG. 6 simultaneously scans through its corresponding sub-sensing element 620 .

[0094] Figure 6B 4×4 sections during beam mode operation consistent with some embodiments of the present disclosure. For example, the beam mode operation may be a SEM inspection. Fig. 6AFollowing the discussed image mode operation, a dividing line 610 may be determined for the sensing element groupings. Here, the sensing element circuit 616a (depicted in gray) on the left side of the dividing line 610 is outside the dividing line, while the sensing element circuit 616b (depicted in black) on the right side of the dividing line 610 is inside. The sensing element circuit 616a may be disabled. For example, the sensing element circuit 616a may be disabled by closing all sub-element switches 622 and the ground switch 644 to send any received charge to ground or by opening all sub-element switches 622 to decouple or disconnect its sub-sensing elements 620 from the signal readout path. In general, there are many switch arrangements that can effectively disable the sensing element circuits. The sensing element circuit 616b inside the dividing line may be enabled by closing all sub-sensing sub-element switches 622 to couple the sub-sensing elements 620 of the sensing element circuit 616b inside the dividing line to the signal readout path. The signal output from the sensing element circuit 616b may correspond to the signal output from Figure 4C The signal output by a single sense element circuit 416 in FIG. 4 is referred to as a beam mode sense element signal.

[0095] During beam mode operation, when all sub-element switches 622 of the sense element circuit 616 are closed, the array of individual sub-sense elements 620 acts as a single conversion element (eg, Figure 4C The sensing elements 415 of the embodiment of the present invention are operated to convert the charged particle landing events into signals. For example, the array of connected sensing elements 620 can be operated in a manner similar to the larger-sized sensing elements 415 of the comparative embodiment. Therefore, the maximum resolution in the image mode can be higher than the maximum resolution in the beam mode.

[0096] Although FIG. 6A to FIG. 6B The arrangement does have a higher switch count to enable high resolution image mode, but parasitics can be minimized by a highly parallel architecture. For example, since the switches at the sensing element are in parallel with the combination of sub-sensing element levels in the sensing element array, in beam mode, the effect of series resistance on analog bandwidth due to the added switches can be reduced, eliminated, or considered negligible.

[0097] Figure 6C The diagram shows a 4×4 segment during beam mode operation consistent with some embodiments of the present disclosure. Figure 6C An embodiment may be similar to Figure 6B Embodiments of the present invention. Part of the sensing element circuit 616c can be implemented in beam mode. Figure 6CAs shown at the bottom of FIG. 6 , the dividing line 610 can be drawn to directly pass through the array of sub-sensing elements 620 in the sensing element circuit 616c. The external sub-sensing element switches 622c1 of the partial sensing elements 616c located outside the dividing line 610 can be opened. The internal sub-sensing element switches 622c2 of the partial sensing elements 616c located inside the dividing line 610 can be closed. Only those sub-sensing elements 620 connected by the internal sub-sensing element switches 622c2 can be coupled to the signal readout path. In this way, a more closely corresponding beam spot (such as Figure 5B For example, the sensing element located on the dividing line 610 can be implemented as a partial sensing element to achieve a stepped or more complex profile for the portion of the dividing line 610 that passes through the sensing element. In addition, the dividing line 610 may include a simple horizontal or vertical line that passes through an inner portion of the sensing element 615 rather than around its edge. The partial sensing element arrangement can be beneficial, for example, to reduce crosstalk when two beam spots are close to each other. The signal output from the sensing element circuit 616c can be referred to as a beam mode partial sensing element signal. In some embodiments of the present disclosure using a beam mode partial sensing element, the maximum resolution in the beam mode can be equal to the maximum resolution in the image mode.

[0098] While the above discussion focuses on the state of switch 622, it should be noted that other switches may be changed from the orientation in which they are depicted. For example, various combinations of grouping switches 640 may be closed to group sense element circuits 616b together. One or more element-bus switches 641 may be closed to connect grouped sense element circuits 616b to the signal readout path. Additionally, unused sense element circuits 616a may be connected to signal ground or common voltage 618 via ground switch 644. Additionally, in Figure 6B In the configuration shown in , the sub-element switch 622 is arranged on the bias voltage side, and therefore the effect of the parasitic capacitance from the switch can also be reduced, eliminated, or considered negligible. In some embodiments, the bias side switch can be implemented using conventional manufacturing techniques in the semiconductor chip forming the detector. For example, ion implantation, deposition, etching (e.g., deep reactive ion etching), or other techniques can be used to produce the circuit elements. However, other switch configurations are contemplated in some embodiments of the present disclosure.

[0099] Figure 7 Two possible switch configurations of sub-sensing elements consistent with embodiments of the present disclosure are shown. On the left is the bias side arrangement 715a of the sub-element switch 722, which is also FIG. 6A to FIG. 6B. On the right is the signal side arrangement 715b of the sub-element switch 722. The bias side of the sub-sensing element 720 can refer to the side of the sub-sensing element on which the bias voltage is applied to the detector in operation. The detector can be operated by a bias voltage applied to the sub-sensing element so that the charge carriers generated within the sub-sensing element (due to the electron landing event) are swept to one side or the other, thereby allowing the signal to flow out of the sub-sensing element. The signal side can refer to the side of the sub-sensing element where the signal flows into or out of the sub-sensing element. The signal side can coincide with the incident side of the detector. The bias side implementation 716a can minimize parasitic capacitance from the switch. The implementation of 716b can allow all circuit components and related connections to be arranged on one side of the detector chip, which can reduce chip processing requirements, thereby reducing manufacturing costs.

[0100] In addition to switch placement, parasitic parameters can also be further reduced through switch design. Fig. 8A The parasitic capacitance of a MOSFET 823, which is a key component of some analog switch designs, is shown. The MOSFET includes a gate G, a body region B, a source S, and a drain D. Fig. 8A The left and right sides of the diagram show the parasitic capacitance of the MOSFET in the off and on states, respectively. When the switch is on, only the parasitic capacitance C between the gate G and the drain D needs to be considered. GD , C between the gate G and the source S GS , C between body region B and drain D DB , and C between the body region B and the source S SB . Figure 8B The diagram includes Fig. 8A FIG. 8 is a simplified circuit diagram of an analog switch design 822 for a MOSFET design. Bootstrapping techniques may be used to reduce parasitic capacitance from the MOSFET in the signal side analog switch.

[0101] In some embodiments of the present disclosure, the detector may be configured to select a preferred balance between resolution and signal readout speed. As resolution increases, the signal readout speed in image mode may decrease because, for example, it may take longer to individually address a large number of sub-sensing elements. Therefore, in some embodiments of the present disclosure, it may be advantageous to group the sub-sensing elements together into subgroups in order to reduce the number of individual sub-sensing element readouts that must be performed.

[0102] For example, it may be preferred to divide the alignment process of the secondary column of a multi-beam tool into coarse and fine stages. Initially, during the coarse stage, the resolution may be reduced by grouping the sub-sensing elements above in order to achieve a higher readout speed. This may enable rapid feedback adjustment of the elements in the secondary column to accelerate coarse adjustment. When the coarse adjustment is complete, the fine stage may be implemented. The fine stage may utilize a lower readout speed that facilitates higher resolution by actuating the sub-sensing elements individually or in smaller groups to increase feedback accuracy. Using the coarse and fine stages, secondary column adjustments may be achieved quickly and accurately.

[0103] Fig. 9 Two possible examples of subgroups 923 (e.g., 923a and 923b) of sub-sensing elements 920 in image mode consistent with embodiments of the present disclosure are illustrated, which can achieve higher readout speeds. Subgroups 923 can be implemented by closing more than one sub-element switch at a time during image mode operation. Each subgroup 923 then outputs a combined (e.g., summed) signal of its sub-sensing element 920. Fig. 9 , the sensing element 915a is divided into a set of uniform subgroups 923a, each subgroup having four sub-sensing elements 920. Since the four sub-sensing elements 920 are simultaneously connected to the sensing element node, the output signals within the subgroup are coupled. The coupled signals can be referred to as image mode subgroup pixel signals. Image mode operation can be performed by sequentially addressing each subgroup 923a within the sensing element 915a, rather than individually addressing each sub-sensing element in the sub-sensing element 920. Therefore, the reduction in the number of individually addressing steps (for example, a 75% reduction here) results in an improvement in the image mode readout speed.

[0104] The sub-sensing elements may also be divided into non-uniform groups, such as in sub-group 923b. Fig. 9 As shown on the right side of , the sub-sensing elements 920 inside the sensing element 915b are divided into nine subgroups 923b. One subgroup has four sub-sensing elements 920, each of the four subgroups has two sub-sensing elements 920, and each of the four subgroups has one sub-sensing element 920. Any suitable arrangement of the subgroups 923 can be selected. The arrangement need not be rectangular, and the grouped sub-sensing elements 920 need not be adjacent. By way of example, the first subgroup 923 can be composed of four sub-sensing elements 920 located at the corners of the sensing element 915, and the second subgroup 923 can be a cross-shaped subgroup composed of the remaining sub-sensing elements.

[0105] It should be understood that the above arrangement can be achieved by manufacturing a detector with fewer sub-elements than the illustrated 4×4 example. For example, sub-group 923a can be achieved by a 2×2 array of sub-sensing elements 920. Sub-group 923b can be achieved by a 3×3 array of sub-sensing elements 920 of different sizes. Fig. 9 The icon shows the dynamic ability to adjust the grouping. This can be used to select the preferred trade-off between speed and resolution according to requirements.

[0106] Fig.10 A method 1000 of using a detector having sub-sensing elements consistent with an embodiment of the present disclosure is illustrated. The detector may include Figure 1 , Figure 2 , FIG. 3A to FIG. 3B , FIG. 5A to FIG. 5C , FIG. 6A to FIG. 6B , Figure 7 or FIG. 8A to FIG. 8B The detector or element disclosed in .

[0107] In step S1001, an imaging process is started in a charged particle beam device. The charged particle beam device may be, for example, a SEM. The charged particle beam device may be Figure 1 to Figure 2 The imaging process may be an image mode operation for, for example, grouping of sensing elements used in beam mode, SEM tuning or alignment, or any other process where a high resolution image of a beam spot is desired. A primary charged particle beam (e.g., an electron beam) irradiates a surface and the resulting secondary beam (e.g., a secondary or backscattered electron beam) is projected onto a detector.

[0108] Next, the detector is controlled (e.g., by Figure 1 The controller 109 or Figure 2 The image processing system 290 of the present invention sequentially addresses multiple sensing elements. A sensing element may have multiple sub-sensing elements that can be addressed individually. At step S1002, a first (or next) sensing element is addressed by, for example, closing an associated element-bus switch to couple the sensing element to a signal readout path via a common signal bus. Other sensing elements on the same common signal bus or the same dedicated signal readout path may be decoupled or disconnected by opening their associated element-bus switches to allow the signal received at the signal processing circuit to be uniquely associated with the sensing element being addressed.

[0109] At step S1003, a first (or next) sub-sensing element of the first (or next) sensing element is addressed. This is accomplished by closing the associated sub-element switch of the sub-sensing element to connect any signal from the sub-sensing element to the readout path via the sensing element node. In some embodiments, the sub-sensing element may include a sub-sensing element as described above with respect to Fig. 9The sub-sensing element described herein may be a group of sub-sensing elements. In such a case, the sub-element switches include a plurality of sub-element switches corresponding to the sub-elements in the group. During the sub-sensing element addressing step S1003, other (ungrouped) sub-element switches may remain open so that any signal received at the signal processing circuit may be uniquely associated with the sub-sensing element (or group) being addressed. After addressing a sub-sensing element, its sub-element switch may be opened to decouple or disconnect the sub-sensing element from the readout path.

[0110] At step S1004, after the sub-sensing element has been addressed and any signal is received by the signal processing circuit on the readout path, it can be determined whether the first (or next) sensing element has another sub-sensing element to be addressed. If so, the next sub-sensing element can be selected at step S1005, and the addressing is repeated according to step S1003. If the sensing element does not have a sub-sensing element to be addressed, the sensing element can be decoupled or disconnected from the signal readout path by, for example, opening its associated element-bus switch, and the process moves to step S1006.

[0111] At step S1006, it is determined whether there is another sensing element to be addressed. If so, the next sensing element can be selected at step S1007, and the addressing of all sub-sensing elements can be repeated for the next sensing element according to steps 1002 to 1006. When there is no sensing element to be addressed, the addressing process is completed. The information obtained from the imaging process can be used to determine a high-resolution image of the beam spot for grouping boundary determination, SEM tuning / alignment, or used in other ways to affect imaging.

[0112] For example, the method may proceed to step S1010, where an adjustment may be made. The adjustment may include determining or adjusting a grouping of sensing elements or sub-sensing elements. The adjustment may be performed by actuating (e.g., toggling or switching) a switch, such as a switch between adjacent sensing elements, a switch between adjacent segments, a grouping switch, or a sub-element switch. Examples of sub-element switches discussed above include, for example, Figure 5C The sub-element switch 522 shown in FIG. 6A to FIG. 6B The sub-element switch 622 shown in Figure 7. The connection state of the switch can be changed between "on" and "off" or another state (e.g., connected to another branch of the circuit system). The adjustment can be performed to make the beam spot boundary more closely conform to the actual secondary beam spot formed on the detector. In some embodiments, the adjustment may include adjusting the trajectory of the primary beam or beam wave. The adjustment can be performed by adjusting the components of the column of the charged particle beam device. For example, the deflector can be actuated to adjust the beam passing through it. The Wiener filter can be adjusted so that the trajectory of the beam passing through it is affected. In some embodiments, the adjustment may include adjusting the trajectory of the secondary beam projected onto the detector. The adjustment can be performed by adjusting the components of the secondary imaging system, such as a zoom lens, a deflection lens, an aberration compensation element (e.g., an stigmator), an anti-scanning deflector, or any other element that may affect the properties of the beam projected onto the detector. A feedback loop can be provided, in which the information obtained from the process of steps 1001 to 1007 is used to make the adjustment. The adjustment may include performing tuning or alignment of the charged particle beam system. The adjustment may enhance the collection efficiency of secondary particles, or reduce crosstalk of adjacent secondary beam spots on the detector. Crosstalk may be reduced by associating different groups of sensing elements (including sub-sensing elements) with different beam spots. Beam spot identifiers (e.g., first beam spot, second beam spot, ..., nth beam spot) may be associated with groups of sensing elements.

[0113] It should be understood that not all steps need to be performed in the order described. For example, determining which sensing elements and sub-sensing elements need not occur in real time, and opening and closing switches need not occur in the exact order given above. Any switching and determining operations can be used so that spatial information of the sensing elements and sub-sensing elements can be obtained during the image mode process.

[0114] A non-transitory computer readable medium storing a computer program for use with a controller (eg, Figure 1 The controller 109 or Figure 2 The image processing system 290) is used according to the above Fig.10An exemplary flow chart consistent with the embodiments herein detects instructions for a charged particle beam. For example, instructions stored in a non-transitory computer readable medium may be executed by a circuit system of a controller for partially or fully executing method 1000. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, a hard disk, a solid state drive, a tape or any other magnetic data storage medium, a compact disk read-only memory (CD-ROM), any other optical data storage medium, any physical medium with a hole pattern, a random access memory (RAM), a programmable read-only memory (PROM) and an erasable programmable read-only memory (EPROM), a FLASH-EPROM or any other flash memory, a non-volatile random access memory (NVRAM), a cache, a buffer, any other memory chip or cartridge, and networked versions thereof.

[0115] The embodiments of the present disclosure may be further described by the following aspects:

[0116] 1. A charged particle detector configured to operate in an image mode or a beam mode, the charged particle detector comprising:

[0117] a substrate comprising a first plurality of sub-sensing elements configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the first plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a first sensing element node of a first sensing element on a second side of the sub-sensing element,

[0118] wherein each of the first plurality of sub-sensing elements is configured to generate an image mode sub-pixel signal when the charged particle detector operates in the image mode, each image mode sub-pixel signal being individually accessible by a signal processing circuit of the charged particle detector in the image mode, and

[0119] Wherein, the first group of multiple sub-sensing elements is configured to generate a first beam mode sensing element signal when the charged particle detector operates in the beam mode, and the switch coupled to each of the sub-sensing elements in the first group of multiple sub-sensing elements is closed in the beam mode, and the first beam mode sensing element signal can be acquired by the signal processing circuit of the charged particle detector in the beam mode.

[0120] 2. A charged particle detector according to aspect 1, wherein the image mode sub-pixel signal of each sub-sensing element can be individually acquired by the signal processing circuit of the charged particle detector by individually addressing each switch of each sub-sensing element in the first group of multiple sub-sensing elements in the image mode.

[0121] 3. The charged particle detector according to aspect 1, wherein the electrical signal of the image mode sub-pixel signal or the beam mode sensing element signal is one of voltage, current or charge.

[0122] 4. The charged particle detector of aspect 1, wherein the first plurality of sub-sensing elements comprises a plurality of PIN diodes.

[0123] 5. The charged particle detector of aspect 1, wherein each of the sub-sensing elements is coupled to a switch on a bias side of the sub-sensing element.

[0124] 6. The charged particle detector of aspect 1, wherein each of the sub-sensing elements is coupled to a switch on a signal side of the sub-sensing element.

[0125] 7. A charged particle detector according to aspect 1, wherein the first side is a bias side.

[0126] 8. The charged particle detector of aspect 1, wherein the first side is a signal side.

[0127] 9. The charged particle detector of aspect 1, further comprising an element bus switch configured to connect the first sensing element to a signal bus.

[0128] 10. A charged particle detector according to aspect 1, wherein the maximum resolution in the image mode is higher than the maximum resolution in the beam mode.

[0129] 11. The charged particle detector according to aspect 1, further comprising a controller configured to control the charged particle detector to perform the following operations:

[0130] Switching a first switch coupled to a first sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the first sub-sensing element and the sensing element node; and

[0131] A first image mode sub-pixel signal from the first sub-sensing element is processed by the signal processing circuit.

[0132] 12. The charged particle detector according to aspect 11, wherein the controller is further configured to control the charged particle detector to perform the following operations:

[0133] Switching a first switch coupled to the first sub-sensing element to change a connection state between the first sub-sensing element and the first sensing element node;

[0134] Switching a second switch coupled to a second sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the second sub-sensing element and the first sensing element node; and

[0135] A second image mode sub-pixel signal from the second sub-sensing element is processed by the signal processing circuit.

[0136] 13. A charged particle detector according to aspect 12, wherein the controller is further configured to:

[0137] A characteristic of a beam spot on the detector is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

[0138] 14. A charged particle detector according to aspect 13, wherein the characteristic comprises one of spot shape, spot size, boundary determination or spot identification.

[0139] 15. The charged particle detector according to aspect 13, wherein the controller is further configured to:

[0140] Adjustments are performed based on the characteristics.

[0141] 16. The charged particle detector according to aspect 12, wherein the controller is further configured to:

[0142] A grouping of sensing elements used in the beam pattern is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

[0143] 17. The charged particle detector according to aspect 12, wherein the controller is further configured to:

[0144] A parameter adjustment of a charged particle beam device is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

[0145] 18. A charged particle detector according to clause 17, wherein the parameter adjustment of the charged particle beam device is a tuning adjustment of a scanning electron microscope.

[0146] 19. The charged particle detector according to aspect 12, wherein the controller is further configured to:

[0147] Switching a second switch coupled to a second sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the second sub-sensing element and a node of the first sensing element;

[0148] Switching a third switch coupled to a third sub-sensing element of the second plurality of sub-sensing elements to change a connection state of the third sub-sensing element and a second sensing element node of the second sensing element; and

[0149] A third image mode sub-pixel signal from the third sub-sensing element is processed by the signal processing circuit.

[0150] 20. The charged particle detector according to aspect 11, wherein the controller is further configured to control the charged particle detector to perform the following operations:

[0151] switching a second switch coupled to a second sub-sensing element to change a connection state of the second sub-sensing element and the sensing element node, the first switch and the second switch having the same connection state during the same period; and

[0152] A combination of the first image mode sub-pixel signal and the second image mode sub-pixel signal from the first sub-sensing element and the second sub-sensing element is processed by the signal processing circuit into an image mode sub-group pixel signal.

[0153] 21. A charged particle detector according to claim 1,

[0154] The substrate further includes a second plurality of sub-sense elements, each of the sub-sense elements in the second plurality of sub-sense elements being coupled to the switch on the first side and a second sense element node of the second sense element on the second side,

[0155] wherein each sub-sensing element of the second plurality of sub-sensing elements is configured to generate an image-mode sub-pixel signal in an image mode, wherein each image-mode sub-pixel signal can be individually acquired by a signal processing circuit of the charged particle detector in the image mode;

[0156] Wherein, the second group of multiple sub-sensing elements are configured to generate a second beam mode sensing element signal in a beam mode, and a switch coupled to each sub-sensing element in the second group of multiple sub-sensing elements is closed in the beam mode, and the second beam mode sensing element signal can be acquired by the signal processing circuit of the charged particle detector in the beam mode.

[0157] 22. The charged particle detector of aspect 21, further comprising a set switch configured to connect the first sensing element to the second sensing element.

[0158] 23. The charged particle detector of aspect 21, further comprising a controller configured to:

[0159] Switching each switch of the first plurality of sub-sensing elements to change a connection state between each sub-sensing element of the first plurality of sub-sensing elements and the first sensing element node;

[0160] switching each switch of the second plurality of sub-sensing elements to change a connection state between each sub-sensing element of the second plurality of sub-sensing elements and the second sensing element node; and

[0161] A grouped beam mode sensing element signal including a first beam mode sensing element signal and a second beam mode sensing element signal from the first sensing element and the second sensing element is processed by the signal processing circuit.

[0162] 24. The charged particle detector of aspect 21, further comprising a controller configured to:

[0163] Switching each switch of the first plurality of sub-sensing elements to change a connection state between each sub-sensing element of the first plurality of sub-sensing elements and the first sensing element node;

[0164] switching each switch of the second plurality of sub-sensing elements to change a connection state between each sub-sensing element of the second plurality of sub-sensing elements and the second sensing element node; and

[0165] Grouped beam mode sensing element signals including a first beam mode sensing element signal from the first sensing element are processed by the signal processing circuit.

[0166] 25. The charged particle detector of aspect 1, wherein the first plurality of sub-sensing elements are further configured to generate beam mode partial sensing element signals when the charged particle detector is operated in a second beam mode,

[0167] a first subset of switches coupled to each sub-sensing element in a first subset of sub-sensing elements in the first plurality of sub-sensing elements being closed in the second beam mode,

[0168] a second subset of switches coupled to each sub-sensing element in a second subset of sub-sensing elements in the first plurality of sub-sensing elements being opened in a second beam mode,

[0169] The beam mode portion sensing element signal can be acquired by a signal processing circuit of the charged particle detector in the second beam mode.

[0170] 26. An electronic detector comprising:

[0171] a substrate comprising a plurality of PIN diodes, each of the diodes being coupled to the switch on one side and to a beam pixel node on the other side, each of the PIN diodes forming an image mode pixel when in image mode, a signal of each image mode pixel being capable of being acquired by the detector when in image mode; and

[0172] A plurality of groups of PIN diodes, each of the PIN diodes in each group being part of a beam mode pixel of the group comprising the PIN diodes when in beam mode, wherein the PIN diodes in each group are connected together via switches on the beam pixel node side of each of the switches to enable the beam mode, and signals of the beam mode pixels can be acquired by the detector when in beam mode.

[0173] 27. A method of operating a charged particle beam detector, the charged particle beam detector being configured to operate in an image mode or a beam mode, the method comprising:

[0174] addressing a first sensing element of a plurality of sensing elements of the charged particle beam detector by connecting the first sensing element to a signal readout path of the charged particle beam detector, the first sensing element comprising a first plurality of sub-sensing elements, each sub-sensing element being configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the first plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a first sensing element node of the first sensing element on a second side of the sub-sensing element;

[0175] When addressing the first sensing element, individually addressing each sub-sensing element of the first sensing element by sequentially turning on and off each switch coupled to each sub-sensing element to individually connect each sub-sensing element of the first sensing element to the signal readout path; and

[0176] Adjustments are performed on a charged particle beam device including the charged particle beam detector based on the signal obtained from the first sensing element on the signal readout path.

[0177] 28. The method of aspect 27, wherein:

[0178] turning on each switch coupled to each sub-sensing element allows the charge generated in the sub-sensing element to flow to the signal readout path; and

[0179] Opening each switch coupled to each sub-sensing element prevents charges generated in the sub-sensing element from flowing to the signal readout path.

[0180] 29. The method according to aspect 27, further comprising:

[0181] disconnecting the first sensing element from the signal readout path;

[0182] addressing a second sensing element of the plurality of sensing elements of the charged particle beam detector by connecting the second sensing element to a signal readout path of the charged particle beam device, the second sensing element comprising a second plurality of sub-sensing elements, each sub-sensing element being configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the second plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a second sensing element node of the second sensing element on a second side of the sub-sensing element; and

[0183] when addressing the second sensing element, individually addressing each sub-sensing element of the second sensing element by sequentially turning on and off each switch coupled to each sub-sensing element one at a time to individually connect each sub-sensing element of the second sensing element to the signal readout path;

[0184] Wherein, the adjusting of the charged particle beam device is further performed based on a signal obtained from the second sensing element on the signal readout path.

[0185] 30. The method of clause 27, wherein the adjustment of the charged particle beam device comprises adjustment of the charged particle beam detector.

[0186] 31. A method according to clause 30, wherein adjusting the charged particle beam detector comprises configuring or adjusting grouping of sensing elements.

[0187] 32. The method of clause 27, wherein the adjustment of the charged particle beam device comprises adjustment of components of the charged particle beam device other than the charged particle beam detector.

[0188] 33. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a charged particle beam device to cause the device to perform a method comprising:

[0189] addressing a first sensing element of a plurality of sensing elements of a charged particle beam detector by connecting the first sensing element to a signal readout path of the charged particle beam device, the first sensing element comprising a first plurality of sub-sensing elements, each sub-sensing element being configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the first plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a first sensing element node of the first sensing element on a second side of the sub-sensing element;

[0190] When addressing the first sensing element, individually addressing each sub-sensing element of the first sensing element by sequentially turning on and off each switch coupled to each sub-sensing element one at a time to individually connect each sub-sensing element of the first sensing element to the signal readout path; and

[0191] Adjustments are performed on the charged particle beam device based on the signal obtained from the first sensing element on the signal readout path.

[0192] 34. The non-transitory computer-readable medium of clause 33, wherein:

[0193] turning on each switch coupled to each sub-sensing element allows the charge generated in each sub-sensing element to flow to the signal readout path; and

[0194] Opening each switch coupled to each sub-sensing element prevents charges generated in each sub-sensing element from flowing to the signal readout path.

[0195] 35. The non-transitory computer-readable medium of aspect 33, wherein the set of instructions executable by at least one processor of the charged-particle beam device causes the device to further perform the following operations:

[0196] disconnecting the first sensing element from the signal readout path;

[0197] addressing a second sensing element of the plurality of sensing elements of the charged particle beam detector by connecting the second sensing element to a signal readout path of the charged particle beam device, the second sensing element comprising a second plurality of sub-sensing elements, each sub-sensing element being configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the second plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a second sensing element node of the second sensing element on a second side of the sub-sensing element; and

[0198] when addressing the second sub-sensing element, individually addressing each sub-sensing element of the second sensing element by sequentially turning on and off each switch coupled to each sub-sensing element one at a time to individually connect each sub-sensing element of the second sensing element to the signal readout path;

[0199] Wherein, the adjusting of the charged particle beam device is further performed based on a signal obtained from the second sensing element on the signal readout path.

[0200] 36. The non-transitory computer-readable medium of clause 33, wherein the adjustment to the charged-particle beam device comprises an adjustment to the charged-particle beam detector.

[0201] 37. The non-transitory computer-readable medium of aspect 36, wherein adjusting the charged particle beam detector comprises configuring or adjusting grouping of sensing elements.

[0202] 38. The non-transitory computer-readable medium of clause 33, wherein the adjustment to the charged-particle beam device comprises adjustment to a component of the charged-particle beam device other than the charged-particle beam detector.

[0203] It will be appreciated that the embodiments of the present disclosure are not limited to the exact configurations that have been described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope of the present disclosure. 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 by consideration of the specification and practice of the invention disclosed herein. It is intended that the present specification and examples be regarded as exemplary only, with the true scope and spirit of the present invention being indicated by the appended claims.

Claims

1. A charged particle detector configured to operate in an image mode or a beam mode, the charged particle detector comprising: a substrate comprising a first plurality of sub-sensing elements configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the first plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a first sensing element node of a first sensing element on a second side of the sub-sensing element, wherein each of the first plurality of sub-sensing elements is configured to generate an image mode sub-pixel signal when the charged particle detector operates in the image mode, each image mode sub-pixel signal being individually accessible by a signal processing circuit of the charged particle detector in the image mode, and Wherein, the first group of multiple sub-sensing elements is configured to generate a first beam mode sensing element signal when the charged particle detector operates in the beam mode, and the switch coupled to each of the sub-sensing elements in the first group of multiple sub-sensing elements is closed in the beam mode, and the first beam mode sensing element signal can be acquired by the signal processing circuit of the charged particle detector in the beam mode.

2. The charged particle detector according to claim 1, wherein: An image mode sub-pixel signal of each sub-sensing element in the first plurality of sub-sensing elements may be individually acquired by signal processing circuitry of the charged particle detector by individually addressing each switch of each sub-sensing element in the image mode.

3. The charged particle detector according to claim 1, wherein: The electrical signal of the image mode sub-pixel signal or the beam mode sensing element signal is one of voltage, current or charge. 4 . The charged particle detector of claim 1 , further comprising an element bus switch configured to connect the first sensing element to a signal bus.

5. The charged particle detector according to claim 1 , further comprising a controller configured to control the charged particle detector to perform the following operations: Switching a first switch coupled to a first sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the first sub-sensing element and the sensing element node; and A first image mode sub-pixel signal from the first sub-sensing element is processed by the signal processing circuit.

6. The charged particle detector according to claim 5, wherein: The controller is further configured to control the charged particle detector to perform the following operations: Switching a first switch coupled to the first sub-sensing element to change a connection state between the first sub-sensing element and the first sensing element node; Switching a second switch coupled to a second sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the second sub-sensing element and a node of the first sensing element; as well as A second image mode sub-pixel signal from the second sub-sensing element is processed by the signal processing circuit.

7. The charged particle detector according to claim 6, wherein: The controller is also configured to: A characteristic of a beam spot on the detector is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

8. The charged particle detector according to claim 7, wherein: The characteristic comprises one of spot shape, spot size, boundary determination or spot identification.

9. The charged particle detector according to claim 7, wherein: The controller is also configured to: Adjustments are performed based on the characteristics.

10. The charged particle detector according to claim 6, wherein: The controller is also configured to: A grouping of sensing elements for use in the beam pattern is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

11. The charged particle detector according to claim 6, wherein: The controller is also configured to: A parameter adjustment of a charged particle beam device is determined based on the first image pattern sub-pixel signal and the second image pattern sub-pixel signal.

12. The charged particle detector according to claim 6, wherein: The controller is also configured to: Switching a second switch coupled to a second sub-sensing element of the first plurality of sub-sensing elements to change a connection state between the second sub-sensing element and a node of the first sensing element; Switching a third switch coupled to a third sub-sensing element of the second plurality of sub-sensing elements to change a connection state between the third sub-sensing element and a second sensing element node of the second sensing element; as well as A third image mode sub-pixel signal from the third sub-sensing element is processed by the signal processing circuit.

13. The charged particle detector according to claim 1, The substrate further includes a second plurality of sub-sense elements, each of the sub-sense elements in the second plurality of sub-sense elements being coupled to the switch on the first side and a second sense element node of the second sense element on the second side, in, each sub-sensing element of the second plurality of sub-sensing elements is configured to generate an image-mode sub-pixel signal in an image mode in which each image-mode sub-pixel signal is individually accessible by a signal processing circuit of the charged particle detector; Wherein, the second group of multiple sub-sensing elements are configured to generate a second beam mode sensing element signal in a beam mode, and a switch coupled to each sub-sensing element in the second group of multiple sub-sensing elements is closed in the beam mode, and the second beam mode sensing element signal can be acquired by the signal processing circuit of the charged particle detector in the beam mode.

14. The charged particle detector of claim 13, further comprising a controller configured to: Switching each switch of the first plurality of sub-sensing elements to change a connection state between each sub-sensing element of the first plurality of sub-sensing elements and the first sensing element node; switching each switch of the second plurality of sub-sensing elements to change a connection state between each sub-sensing element of the second plurality of sub-sensing elements and the second sensing element node; as well as A grouped beam mode sensing element signal including a first beam mode sensing element signal and a second beam mode sensing element signal from the first sensing element and the second sensing element is processed by the signal processing circuit.

15. A non-transitory computer readable medium storing a set of instructions executable by at least one processor of a charged particle beam device to cause the device to perform a method comprising: addressing a first sensing element of a plurality of sensing elements of a charged particle beam detector by connecting the first sensing element to a signal readout path of the charged particle beam device, the first sensing element comprising a first plurality of sub-sensing elements, each sub-sensing element being configured to convert a charged particle landing event into an electrical signal, each of the sub-sensing elements of the first plurality of sub-sensing elements being coupled to a switch on a first side of the sub-sensing element and to a first sensing element node of the first sensing element on a second side of the sub-sensing element; when addressing the first sensing element, individually addressing each sub-sensing element of the first sensing element by sequentially turning on and off each switch coupled to each sub-sensing element one at a time to individually connect each sub-sensing element of the first sensing element to the signal readout path; as well as Adjustments are performed on the charged particle beam device based on the signal obtained from the first sensing element on the signal readout path.

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