Charged particle beam detector with adaptive detection area set for multiple fields of view

Abstract

The charged particle beam detector may include a plurality of detector segments designed to accommodate a field of view (FOV) of the charged particle beam device. The first detector section may form a first detector region configured to capture emitted charged particles of a smaller FOV size. The second detector section may surround the first detector section to form a second detector region configured to capture emitted charged particles of a larger FOV size. The first detector region may have a lower noise component due to a smaller junction capacitance in a smaller detection surface area.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of U.S. Application No. 63 / 421,870, filed on November 2, 2022, and U.S. Application No. 63 / 591,417, filed on October 18, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The description herein relates to detectors in the field that can be used in charged particle beam systems, and more particularly, to systems and methods that can be adapted for charged particle detection using charged particle counting. Background Art

[0004] Detectors can be used to sense physically observable phenomena. For example, charged particle beam tools (such as electron microscopes) can include detectors that receive charged particles projected from a sample and output a detection signal. The detection signal can be used to reconstruct an image of the structure of the sample under inspection and can be used, for example, to reveal defects in the sample. In the manufacture of semiconductor devices, which may include a large number of densely packaged micro integrated circuit (IC) components, detecting defects in samples is becoming increasingly important. For this purpose, inspection systems can be provided.

[0005] Existing detection systems may have an undesirably high signal-to-noise ratio (SNR). A further consideration may be the charged particle beam collection rate. Summary of the Invention

[0006] Embodiments of the present disclosure provide systems and methods for detection based on charged particle beams. Some embodiments of the present disclosure provide a segmented multi-channel detector. The segmented multi-channel detector can include a first detector region and a second detector region. The first detector region can have a first segment, and the second detector region can have a first segment and a second segment. The second segment can surround at least 50% of the first segment. The first detector region can include a first noise value of a noise parameter, and the second detector region can include a second noise value of the noise parameter, the second noise value being higher than the first noise value.

[0007] Some embodiments of the present disclosure provide a charged particle beam device including the above-mentioned segmented multi-channel detector. The charged particle beam device can further include: a charged particle beam source configured to generate a primary charged particle beam; and a charged particle optical system configured to scan the primary charged particle beam over a field of view (FOV) on the surface of a sample.

[0008] Some embodiments of the present disclosure provide a method for detecting charged particle events in a charged particle detector. The method may include: performing a first scan of a sample surface with a charged particle beam at a first exposure setting such that emitted charged particles from the sample surface land in a first detector region of the charged particle detector, the first detector region including a first noise value of a noise parameter; generating a first image based on the first scan; performing a second scan of the sample surface with the charged particle beam at a second exposure setting such that emitted charged particles from the sample surface land in a second detector region of the charged particle detector, the second detector region including a second noise value of the noise parameter, the second noise value being higher than the first noise value; and generating a second image based on the second scan, the first image having a higher accuracy than the accuracy of the second image. The first detector region may include a first section of the charged particle detector, and the second detector region may include the first section and a second section of the charged particle detector. The second detector region may be larger than the first detector region.

[0009] Some embodiments of the present disclosure provide a non - transitory computer - readable medium. The non - transitory computer - readable medium may store a set of instructions that, when executed by at least one processor of a device, cause the device to perform the above - described method.

[0010] Some embodiments of the present disclosure provide a charged particle detector. The charged particle detector may include: a top conductive layer including a detection surface; a bottom conductive layer; a semiconductor region between the top conductive layer and the bottom conductive layer, the semiconductor region including a first doped region of a first conductivity type adjacent to the top conductive layer, a second doped region of a second conductivity type (the second conductivity type being different from the first conductivity type) adjacent to the bottom conductive layer, and an intrinsic region between the first doped region and the second doped region; and an aperture configured to allow a primary charged particle beam to pass through, wherein the detection surface extends to the edge of the aperture.

[0011] It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and do not limit the disclosed embodiments as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0013] Figure 1 is a schematic representation of an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0014] Figures 2A - 2C is a diagram illustrating a charged particle beam device that may be an example of an electron beam tool consistent with embodiments of the present disclosure.

[0015] Figures 3A - 3D is a schematic representation of the structure of a detector.

[0016] Figure 4 is a schematic representation of a sample field of view (FOV) and a corresponding detection surface consistent with an embodiment of the present disclosure.

[0017] Figure 5 is a schematic representation illustrating various elements that may cause noise in an imaging channel of a charged particle detector consistent with an embodiment of the present disclosure.

[0018] Figures 6A - 6D is a schematic representation of an exemplary segmented charged particle detector consistent with an embodiment of the present disclosure.

[0019] Figures 7A - 7C is a schematic representation of an exemplary segmented charged particle detector consistent with an embodiment of the present disclosure.

[0020] Figure 8 is a flowchart illustrating an exemplary method for detecting charged particles consistent with an embodiment of the present disclosure.

[0021] Figure 9 is a flowchart illustrating an exemplary method for detecting charged particles consistent with an embodiment of the present disclosure.

[0022] Figures 10A - 10C is a schematic representation of a charged particle detector according to an embodiment of the present disclosure.

[0023] Figures 11A - 11B is a schematic representation of a charged particle detector consistent with an embodiment of the present disclosure. Detailed Description

[0024] 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, where like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments set forth in the following description of the exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices, systems, and methods consistent with aspects related to the subject matter recited in the appended claims. For example, although some embodiments are described in the context of using a charged particle beam (e.g., an electron beam), the present disclosure is not limited thereto. Other types of charged particle beams (e.g., a photon beam) can be similarly applied. Additionally, other imaging systems can be used, such as optical imaging, photoelectric detection, X-ray detection, and the like.

[0025] An electronic device is composed of circuits formed on a silicon wafer called a substrate. Many circuits can be formed together on the same silicon wafer and are called integrated circuits or ICs. With the progress of technology, the size of these circuits has been greatly reduced, so more circuits can be installed on the substrate. For example, the IC chip in a smartphone can be as small as a fingernail, but can include more than 2 billion transistors, each transistor being less than 1 / 1,000 the width of a human hair.

[0026] Manufacturing these ICs with extremely small structures or components is a complex, time-consuming, and expensive process, usually involving hundreds of individual steps. Even an error in one step can lead to defects in the finished IC, making it useless. Therefore, one goal of the manufacturing process is to avoid such defects to maximize the number of functional ICs manufactured in the process; that is, to increase the overall yield of the process.

[0027] One element in increasing the yield is to monitor the chip manufacturing process to ensure that a sufficient number of functional integrated circuits are produced. One way to monitor the process is to inspect the chip circuit structure at various stages of its formation. A scanning charged particle microscope ("SCPM") can be used for the inspection. For example, the SCPM can be a scanning electron microscope (SEM). The SEM can be used to image these extremely small structures, effectively taking "pictures" of the structures. The image can be used to determine whether the structure is formed correctly and whether the structure is formed in the correct position. If the structure is defective, then the process can be adjusted so that the defect is less likely to occur again. To increase throughput (e.g., the number of samples processed per hour), it is desirable to perform the inspection as quickly as possible.

[0028] The working principle of an SEM is similar to that of a raster-scanning camera. A raster-scanning camera takes pictures by receiving and recording the intensity of light reflected or emitted from a person or object pixel by pixel. An SEM takes a "picture" by receiving and recording the energy or number of electrons reflected or emitted from the structure of a wafer. Before taking such a "picture", an electron beam can be projected onto the structure, and when electrons are reflected or emitted ("ejected") from the structure (e.g., from the wafer surface, from structures below the wafer surface, or both), the detector of the SEM can receive and record the energy or number of these electrons to generate an inspection image. To take such a "picture", the electron beam can scan across the wafer (e.g., in a row-by-row or zigzag pattern), and the detector can receive the ejected electrons from the area (referred to as the "beam spot") where the electron beam is projected. The detector can receive and record the ejected electrons from each beam spot at a time, and combine the information recorded for all beam spots to generate an inspection image. Some SEMs use a single electron beam (referred to as a "single-beam SEM") to take a single "picture" to generate an inspection image, while some SEMs use multiple electron beams (referred to as "multi-beam SEMs") to take multiple "sub-pictures" of the wafer in parallel, and in some instances stitch them together to generate an inspection image. By using multiple electron beams, an SEM can direct more electron beams onto the structure to obtain these multiple "sub-pictures", resulting in more electrons being ejected from the structure. Therefore, the detector can receive more ejected electrons simultaneously and generate an inspection image of the structure of the wafer with higher efficiency and faster speed.

[0029] Typically, the detection process involves measuring the amplitude of the electrical signal generated when electrons land on the detector. The intensity of the secondary beam can be determined based on the electrical signal generated in the detector that varies in proportion to the intensity change of the secondary beam.

[0030] To obtain accurate intensity readings and generate accurate images, it is important to collect as many ejected electrons as possible. Since electrons tend to land on the detector surface in a scattered distribution (such as clusters spreading out from their center), one way to achieve a higher collection rate is to provide a larger detection surface area. However, as the detection surface area increases, some unwanted electrical effects become more pronounced. These unwanted effects increase the noise in the detection signal. For example, the junction capacitance is an electrical parameter that may be directly related to the size of the detection surface. Therefore, it may be desirable to provide the detector with only the surface area required to capture sufficient electrons under a given exposure.

[0031] However, electron beam tools (such as SEM tools) operate at different settings, which can change the amount of surface area required. For example, an SEM tool may scan a larger or smaller portion of the sample surface, which is referred to as the field of view (FOV). When scanning a large FOV, a larger detection surface is needed to collect enough electrons for accurate measurement. Therefore, it may be desirable to provide a detector with multiple detector surface segments that are customized to match the expected electron distribution from different FOV sizes. Conventional segmented detectors may not be designed in a way that effectively and efficiently captures these different distributions.

[0032] Embodiments of the present disclosure may provide a segmented charged particle detector. The detector may include a first segment that is designed to capture most of the electrons emitted from a scan of a small FOV. The first segment may have a shape that matches the small FOV, such as a rectangle-based shape. For example, the rectangle-based shape may be substantially square, substantially rectangular, or it may have a shape that matches the expected electron distribution from the small FOV, such as a distorted square shape. The first segment may form a first detection region. The first detection region may have a lower noise value due to its small size and may thus produce an image with higher accuracy.

[0033] The detector may include a second segment that surrounds the first segment and has a similar shape. When combined with the first segment, the second segment may be designed to capture most of the electrons emitted from a scan of a large FOV. The first segment and the second segment may have a shape that matches the large FOV, such as a rectangle-based shape. For example, the rectangle-based shape may be substantially square, substantially rectangular, or it may be a shape that matches the expected electron distribution from the large FOV, such as a distorted square shape. The first segment and the second segment may form a second detection region. The second detection region may have a higher noise value due to its larger size and may thus produce an image with lower accuracy. However, the second detection region may capture a greater number of electrons than the first detection region.

[0034] In this way, the detector may allow a trade-off to be made between noise and collection rate, depending on the parameters of a particular charged particle beam exposure. In some embodiments, parameters other than the FOV size may affect the choice of detection region. For example, as discussed further below, the electron distribution on the detector surface may be affected by other settings in the exposure system, such as landing energy.

[0035] The objects and advantages of the present disclosure may be realized by the elements and combinations set forth in the embodiments discussed herein. However, the embodiments of the present disclosure do not necessarily need to achieve such exemplary objects or advantages, and some embodiments may not achieve any of the stated objects or advantages.

[0036] Without limiting the scope of the present disclosure, some embodiments may be described in the context of a detection system and a detection method provided in a system utilizing an electron beam (“e-beam”). However, the present disclosure is not limited thereto. Other types of charged particle beams (such as proton beams) may be similarly applied. In addition, the system and method for detection may be used in other imaging systems (such as optical imaging, photon detection, proton detection, X-ray detection, ion detection, etc.). Photon detection may include light in the infrared, visible light, UV, DUV, EUV, X-ray, or any other wavelength range. Therefore, although the detector in the present disclosure may be disclosed with respect to electron detection, some embodiments of the present disclosure may be directed to detecting other charged particles or photons.

[0037] As used herein, unless otherwise expressly stated, the term “or” covers all possible combinations, unless infeasible. For example, if it is stated that a component includes A or B, then, unless otherwise expressly stated or infeasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component includes A, B, or C, then, unless otherwise expressly stated or infeasible, 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.

[0038] Now refer to Figure 1 which illustrates an exemplary electron beam inspection (EBI) system 10 that may be used for wafer inspection and is consistent with an embodiment of the present disclosure. As Figure 1 shown, the EBI system 10 includes a main chamber 11, a load / lock chamber 20, an electron beam tool 100 (e.g., a scanning electron microscope (SEM)), and an equipment front end module (EFEM) 30. The electron beam tool 100 is located within the main chamber 11 and may be used for imaging. The EFEM 30 includes a first load port 30a and a second load port 30b. The EFEM 30 may include additional load ports. The first load port 30a and the second load port 30b receive a wafer front opening unified pod (FOUP) that contains wafers (e.g., semiconductor wafers or wafers made of other materials) or samples to be inspected (wafers and samples may be collectively referred to as “wafers” herein).

[0039] One or more robotic arms (not shown) in the EFEM 30 can transfer the wafer to the load / lock chamber 20. The load / lock chamber 20 is connected to a load / lock vacuum pump system (not shown), which removes gas molecules in the load / lock chamber 20 to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) can transfer the wafer from the load / lock chamber 20 to the main chamber 11. The main chamber 11 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules in the main chamber 11 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer will be inspected by the electron beam tool 100. The electron beam tool 100 can be a single-beam system or a multi-beam system. The controller 109 is electrically connected to the electron beam tool 100 and can also be electrically connected to other components. The controller 109 can be a computer configured to perform various controls of the EBI system 10. Although the controller 109 is shown in Figure 1 the exterior of the structure including the main chamber 11, the load / lock chamber 20, and the EFEM 30, it should be understood that the controller 109 can be a part of the structure.

[0040] In some embodiments, the controller 109 can include one or more processors (not shown). The processor can be a general-purpose or special-purpose electronic device capable of manipulating or processing information. For example, the processor can 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), generic array logic (GALs), complex programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), system-on-chips (SoCs), application-specific integrated circuits (ASICs), and any combination of any type of circuit capable of data processing. The processor can also be a virtual processor, which includes one or more processors distributed across multiple machines or devices coupled via a network.

[0041] In some embodiments, the controller 109 may further include one or more memories (not shown). The memory may be a general-purpose or special-purpose electronic device capable of storing code and data that can be accessed by a processor (e.g., via a bus). For example, the memory may include any combination of any number of random access memories (RAMs), read-only memories (ROMs), optical discs, magnetic disks, hard disk drives, solid-state drives, flash drives, secure digital (SD) cards, memory sticks, compact flash (CF) cards, or any type of storage device. The code and data may include an operating system (OS) and one or more applications (or "apps") for specific tasks. The memory may also be virtual memory, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0042] A charged particle beam microscope (such as a charged particle beam microscope formed by or that may be included in the EBI system 10) may have a resolution as low as, for example, the nanometer scale, and may be used as a practical tool for inspecting IC components on a wafer. Using an e-beam system, the electrons of the primary electron beam can be focused at a probe spot on the wafer being inspected. The interaction of the primary electrons with the wafer can result in the formation of a secondary particle beam. The secondary particle beam may include backscattered electrons, secondary electrons, Auger electrons, etc. generated by the interaction of the primary electrons with the wafer. The characteristics (e.g., intensity) of the secondary particle beam may vary based on the internal or external structure or material properties of the wafer, and thus may indicate whether the wafer includes a defect.

[0043] A detector can be used to determine the intensity of the secondary particle beam. The secondary particle beam can form a beam spot on the surface of the detector. The detector can generate an electrical signal (e.g., current, charge, voltage, etc.) representing the detected intensity of the secondary particle beam. A measurement circuit device can be utilized to measure the electrical signal, which can include other components (e.g., an analog-to-digital converter) to obtain the distribution of the detected electrons. The electron distribution data collected during a detection time window, combined with the corresponding scan path data of the primary electron beam incident on the wafer surface, can be used to reconstruct an image of the wafer structure or material under inspection. The reconstructed image can be used to reveal various features of the internal or external structure or material of the wafer and can be used to reveal possible defects in the wafer. There are two ways for CD-SEM to perform image reconstruction based on signals: integrating the amplitude of the signal in each scanned pixel; or based on signal pulse edge detection and discrimination. At each scanned pixel position, multiple electrical signal pulses collected by different detector segments may have different pulse shapes. These different pulse shapes contain information about the electron energy distribution collected by the detector. Electrons with higher energy may result in a faster rise time of the electrical pulse shape. By using multiple segments (4 channels) of the detector, up to 4 pulse edge detection image channels can be used to perform electron energy analysis, thereby generating a higher SEM resolution.

[0044] Figure 2A Illustrated is a charged particle beam apparatus consistent with an embodiment of the present disclosure, which can be an example of the electron beam tool 100. Figure 2A Shown is an apparatus that uses multiple beamlets formed by a primary electron beam to simultaneously scan multiple positions on a wafer.

[0045] As Figure 2A shown, the electron beam tool 100A can include an electron source 202, a gun aperture 204, a condenser lens 206, a primary electron beam 210 emitted from the electron source 202, a source conversion unit 212, multiple beamlets 214, 216, and 218 of the primary electron beam 210, a primary projection optical system 220, a wafer stage ( Figure 2A not shown in the figure), multiple secondary electron beams 236, 238, and 240, a secondary optical system 242, and an electron detection device 244. The electron source 202 can generate primary particles (such as electrons of the primary electron beam 210). A controller, an image processing system, etc. can be coupled to the electron detection device 244. The primary projection optical system 220 can include a beam splitter 222, a deflection scanning unit 226, and an objective lens 228. The electron detection device 244 can include detection sub-regions 246, 248, and 250.

[0046] The electron source 202, gun aperture 204, condenser lens 206, source conversion unit 212, beam splitter 222, deflection scanning unit 226, and objective lens 228 can be aligned with the primary optical axis 260 of the apparatus 100A. The secondary optical system 242 and electron detection device 244 can be aligned with the secondary optical axis 252 of the apparatus 100A.

[0047] The electron source 202 can include a cathode, extractor, or anode, where primary electrons can be emitted from the cathode and extracted or accelerated to form a primary electron beam 210 having an intersection point (virtual or real) 208. The primary electron beam 210 can be visualized as being emitted from the intersection point 208. The gun aperture 204 can block the peripheral electrons of the primary electron beam 210 to reduce the size of the detection spots 270, 272, and 274.

[0048] The source conversion unit 212 can include an array of image forming elements ( Figure 2A (not shown in the figure) and an array of beam limiting apertures ( Figure 2A (not shown in the figure). Examples of the source conversion unit 212 can be found in U.S. Patent No. 9,691,586; U.S. Publication No. 2017 / 0025243; and International Application No. PCT / EP2017 / 084429, all of which are incorporated herein by reference in their entirety. The array of image forming elements can include a microdeflector or a microlens array. The array of image forming elements can form multiple parallel images (virtual or real) of the intersection point 208 and the multiple beam waves 214, 216, and 218 of the primary electron beam 210. The array of beam limiting apertures can limit the multiple beam waves 214, 216, and 218.

[0049] The condenser lens 206 can focus the primary electron beam 210. By adjusting the focusing ability of the condenser lens 206 or by changing the radial size of the corresponding beam limiting aperture within the array of beam limiting apertures, the current of the beam waves 214, 216, and 218 downstream of the source conversion unit 212 can be changed. The condenser lens 206 can be an adjustable condenser lens, which can be configured such that the position of its first principal plane is movable. The adjustable condenser lens can be configured to be magnetic, which can cause the off-axis beam waves 216 and 218 to land on the beam limiting aperture at a rotation angle. The rotation angle varies with the focusing ability of the adjustable condenser lens and the position of the first principal plane. In some embodiments, the adjustable condenser lens can be an adjustable anti-rotation condenser lens, which involves an anti-rotation lens having a movable first principal plane. Examples of the adjustable condenser lens are further described in U.S. Publication No. 2017 / 0025241, which is incorporated herein by reference in its entirety.

[0050] The objective lens 228 can focus the beam waves 214, 216, and 218 onto the wafer 230 for inspection and can form a plurality of probe spots 270, 272, and 274 on the surface of the wafer 230. Secondary electron beam waves 236, 238, and 240 can be formed that are emitted from the wafer 230 and travel back to the beam splitter 222 in parallel.

[0051] The beam splitter 222 can be a Wien filter type beam splitter that generates an electrostatic dipole field and a magnetic dipole field. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on the electrons of the beam waves 214, 216, and 218 may be equal in magnitude and opposite in direction to the force exerted by the magnetic dipole field on the electrons. Thus, the beam waves 214, 216, and 218 can pass straight through the beam splitter 222 with a zero deflection angle. However, the total dispersion of the beam waves 214, 216, and 218 generated by the beam splitter 222 may also not be zero. The beam splitter 222 can separate the secondary electron beams 236, 238, and 240 from the beam waves 214, 216, and 218 and direct the secondary electron beams 236, 238, and 240 towards the secondary optical system 242.

[0052] The deflection scanning unit 226 can deflect the sub-beams 214, 216, and 218 to scan the probe spots 270, 272, and 274 over an area on the surface of the wafer 230. In response to the incidence of the beam waves 214, 216, and 218 at the probe spots 270, 272, and 274, secondary electron beams 236, 238, and 240 can be emitted from the wafer 230. The secondary electron beams 236, 238, and 240 can include electrons having an energy distribution that includes secondary electrons and backscattered electrons. The secondary optical system 242 can focus the secondary electron beams 236, 238, and 240 onto the detection sub-regions 246, 248, and 250 of the electron detection device 244. The detection sub-regions 246, 248, and 250 can be configured to detect the corresponding secondary electron beams 236, 238, and 240 and generate corresponding signals that are used to reconstruct an image on the surface of the wafer 230.

[0053] The generated signals can represent the intensities of the secondary electron beams 236, 238, and 240 and can be provided to an image processing system (e.g., such as described below in Figure 2BThe image processing system provided in

[0054] The intensities of the secondary electron beams 236, 238, and 240 can vary according to the external or internal structure of the wafer 230 and can thus indicate whether the wafer 230 includes defects. Additionally, as discussed above, the beam waves 214, 216, and 218 can be projected onto different positions on the top surface of the wafer 230 or onto different sides of the local structure of the wafer 230 to generate secondary electron beams 236, 238, and 240 that may have different intensities. Thus, by mapping the intensities of the secondary electron beams 236, 238, and 240 to the area of the wafer 230, the image processing system can reconstruct an image that reflects the internal or external structural characteristics of the wafer 230.

[0055] The detection sub-regions 246, 248, and 250 can include separate detector packages of an array detector, separate sensing elements, or separate regions. In some embodiments, each detection sub-region can include a single sensing element.

[0056] Although Figure 2A the detector 244 is shown having several detection sub-regions aligned with the secondary optical axis 252, it should be understood that other multi-beam detector arrangements can exist. For example, it should be understood that the detector can correspond to each beam wave, such that there is a different detector for each of the beam waves 214, 216, 218. It should be understood that these different detectors can be positioned under the primary column corresponding to the primary axis 260. For example, these different detectors can be positioned between the primary projection optical system 220 and the wafer stage.

[0057] Now, another example of a charged particle beam device will be referred to Figure 2B for discussion. The electron beam tool 100B (also referred to herein as device 100B) can be an example of an electron beam tool 100 and can be similar to Figure 2A the electron beam tool 100A shown in

[0058] As Figure 2BAs shown in [Figure], apparatus 100B includes a wafer holder 136 supported by a stage 134 to hold a wafer 150 to be inspected. The electron beam tool 100B includes an electron emitter, which may include a cathode 103, an anode 121, and a gun aperture 122. The electron beam tool 100B further includes a beam limiting aperture 125, a condenser lens 126, a column aperture 135, an objective lens assembly 132, and a detector 144. In some embodiments, the objective lens assembly 132 may be an improved SORIL lens, which includes pole pieces 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. During detection or imaging, an electron beam 161 emitted from the tip of the cathode 103 may be accelerated by the anode 121 voltage, pass through the gun aperture 122, the beam limiting aperture 125, the condenser lens 126, and be focused by the improved SORIL lens into a probe spot 170 and impinge on the surface of the wafer 150. The probe spot 170 may be scanned across the surface of the wafer 150 by a deflector (such as deflector 132c or other deflectors in the SORIL lens). The detector 144 may collect secondary or scattered primary particles (such as secondary electrons or scattered primary electrons) emitted from the wafer surface to determine the intensity of the beam, and thus an image of the area of interest on the wafer 150 may be reconstructed.

[0059] An image processing system 199 may also be provided, which includes an image acquirer 120, a storage device 130, and a controller 109. The image acquirer 120 may include one or more processors. For example, the image acquirer 120 may include a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, etc. or a combination thereof. The image acquirer 120 may be communicatively coupled to the detector 144 of the electron beam tool 100B through 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). The image acquirer 120 may receive signals from the detector 144 and may construct an image. Thus, the image acquirer 120 may acquire an image of the wafer 150. The image acquirer 120 may also perform various post-processing functions, such as image averaging, generating profiles, superimposing indicators on the acquired image, etc. The image acquirer 120 may be configured to perform adjustments to the brightness, contrast, etc. of the acquired image. The storage device 130 may be a storage medium (such as a hard disk, a random access memory (RAM), cloud storage, other types of computer-readable memories, etc.). The storage device 130 may be coupled to the image acquirer 120 and may be used to save the scanned raw image data as an initial image and a post-processed image. The image acquirer 120 and the storage device 130 may be connected to the controller 109. In some embodiments, the image acquirer 120, the storage device 130, and the controller 109 may be integrated together as an electronic control unit.

[0060] In some embodiments, the image acquirer 120 may acquire one or more images of a sample based on the imaging signals received from the detector 144. The imaging signals may correspond to scanning operations for performing charged particle imaging. The acquired images may be a single image including a plurality of imaging areas, and the plurality of imaging areas may include various features of the wafer 150. The single image may be stored in the storage device 130. Imaging may be performed based on imaging frames.

[0061] The condenser and illumination optics of the electron beam tool may include or be supplemented by an electromagnetic quadrupole electron lens. For example, as Figure 2B shown, the electron beam tool 100B may include a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lens may be used to control the electron beam. For example, the first quadrupole lens 148 may be controlled to adjust the beam current, and the second quadrupole lens 158 may be controlled to adjust the beam spot size and beam shape.

[0062] Figure 2B An illustration of a charged particle beam apparatus is shown, which may use a single primary beam configured to generate secondary electrons by interacting with the wafer 150. The detector 144 may be placed along the optical axis 105, as in the embodiment Figure 2B shown. The primary electron beam may be configured to travel along the optical axis 105. Accordingly, the detector 144 may include a hole at its center such that the primary electron beam may pass through to reach the wafer 150. Figure 2B An example of the detector 144 is shown, which has an opening at its center. However, some embodiments may use a detector placed off-axis with respect to the optical axis along which the primary electron beam travels. For example, as in the embodiment Figure 2A shown above, a beam splitter 222 may be provided to direct the secondary electron beam towards an off-axis placed detector. The beam splitter 222 may be configured to deflect the secondary electron beam at an angle α towards the electron detection device 244, as Figure 2A shown.

[0063] In some embodiments of the present disclosure, a PIN detector may be used as an in-lens detector in the delay objective SEM column of the EBI system 10. The PIN detector may be placed between the cathode for generating the electron beam and the objective lens. The electron beam emitted from the cathode may be potentiated at -BE keV (typically around -10 kV). The electrons of the electron beam may be immediately accelerated and travel through the column. The column may be at ground potential. Thus, when the electrons pass through the opening 145 of the detector 144, they may travel with a kinetic energy of BE keV. Since the wafer surface potential may be set to -(BE - LE) keV, when passing through the pole pieces of the objective lens, such asFigure 2B Electrons of the pole piece 132a) of the objective lens assembly 132 can be rapidly decelerated to the landing energy LE keV.

[0064] Figure 2C FIG. illustrates an example of a charged particle beam device 100C consistent with an embodiment of the present disclosure. The charged particle beam device 100C can be, for example, Figure 2A the charged particle beam device 100A or Figure 2B the charged particle beam device 100B. Emitted electrons 171 (e.g., including secondary electrons or backscattered electrons) are emitted from the wafer surface by the impact of the electrons of the primary electron beam 105. The deceleration electric field can decelerate the primary electrons as they approach the detection spot 170, and this deceleration electric field can act as an acceleration electric field to accelerate the emitted electrons back towards the surface of the detector 144. For example, as Figure 2C shown in, due to the interaction with the wafer 150 at the detection spot 170, emitted electrons 171 traveling back towards the detector 144 can be generated.

[0065] Emitted electrons 171 from the wafer surface traveling along the optical axis 105 can reach the surface of the detector 144 with a position distribution. As discussed above, the emitted electrons can include, for example, secondary electrons or backscattered electrons. In some embodiments, for example, the distribution can include between 60 - 85% secondary electrons and between 40 - 15% backscattered electrons. The landing point distribution can be offset depending on the emission position and the SEM deflection field (e.g., the scanning field). Thus, in some applications, if the FOV of the SEM image is required, the required size of the PIN detector within the lens can be quite large. Generally, the diameter of the detector can be 10 mm or larger. In some embodiments, the diameter of the detector can be, for example, about 4 to 10 mm.

[0066] The detector 144 can be placed along the optical axis 105. The primary electron beam can be configured to travel along the optical axis 105. Accordingly, the detector 144 can include a hole 145 at its center such that the primary electron beam can pass through to reach the wafer 150. Figures 2B - 2C An example of a detector 144 having an opening at its center is shown. However, some embodiments can use a detector placed off - axis with respect to the optical axis along which the primary electron beam travels. For example, as Figure 2A shown in the example in, a beam splitter 222 can be provided to direct the emitted electron beam towards an off - axis placed detector. The beam splitter 222 can be configured to turn the emitted electron beam at an angle α towards the electron detection device 244, as Figure 2A shown in. Thus, in some embodiments of the present disclosure, a detector without a central opening can be provided.

[0067] Figure 2Athe detector 244 in or Figures 2B - 2C the detector 144 in Figures 2B - 2C may include a sensing element (such as a diode) or a diode-like element, which can convert incident energy into a measurable signal. For example, the sensing element in the detector may include a SPAD, an APD, or a PIN diode. Throughout this disclosure, the sensing element may be represented as a diode, although the sensing element or other components may deviate from the ideal circuit behavior of electronic components (such as diodes, resistors, capacitors, etc.). In an embodiment of this disclosure, the detector in the charged particle beam system may include a pixelated array of a plurality of sensing elements.

[0068] Figures 3A - 3D FIG. illustrates a schematic diagram of detectors 344a-d. The detectors 344a-d may include, for example, an electron detector, other charged particle detectors, or photon detectors. The detectors 344a-d may include an aperture 345 configured to allow a primary electron beam to pass through the detector and impinge on the sample surface. Alternatively, the detectors 344a-d may be configured to be positioned away from the primary beam axis and may not include the aperture 345. The detectors 345a-d may include diodes (such as PIN diodes), scintillators, radiation detectors, and solid-state detectors, as well as other charged particle sensing devices.

[0069] In some embodiments, the detectors 344a-d may include a monolithic detector (e.g., detector 344a) or a segmented detector (e.g., detectors 344b-d). In a monolithic detector, as Figure 3A shown in Figure 3A , the electron detection surface 346 may include a continuous layer of charged particle sensitive material, thereby forming a single segment 350a corresponding to a single imaging channel. The detector 344a may be placed in a charged particle beam device (e.g., a single beam device) such that the central axis of the aperture 345 can be aligned with the beam axis of the primary electron beam.

[0070] In some embodiments, the segmented detector may include two or more segments. In a segmented detector, such as Figure 3B shown in Figure 3B , the electron detection surface 346 may include a discontinuous layer of charged particle sensitive material separated by a non-sensitive material 302 (such as, for example, the substrate material of detector 344b). Thus, the discontinuous layer may be divided into segments 350b and 351b. Each of the segments 350b and 351b may form a separate imaging channel and be coupled to a separate detection output (not shown). The segmented detectors 344b-d (such as Figures 3B - 3DAs shown in [figures], they can be cylindrical with circular, elliptical, or polygonal cross-sections respectively. One or more segments of the segmented detector can be arranged radially, circumferentially, or azimuthally in a symmetric manner around the beam axis of the primary electron beam. The charged particle sensitive material can be sensitive to charged particles (such as electrons). Alternatively, the detectors 344a-d can be configured to detect charged particles other than electrons (such as, for example, protons). Additionally, the detectors 344a-d can be configured to detect photons instead of charged particles, such as light in the IR, visible light, UV, DUV, EUV, X-ray, or any other wavelength range.

[0071] In some embodiments, the segmented detector can include more than two segments. For example, Figure 3C the segmented detector 344c can include four segments 350c, 351c, 352c, and 353c, which are arranged circumferentially around the central aperture 345. The four segments can be separated by non-sensitive material 302 (such as the substrate used for detector 344c). Each segment 350c, 351c, 352c, and 353c can form a separate imaging channel and be coupled to a separate detection output. Thus, the segmented detector 344c can represent a four-channel detector.

[0072] In some embodiments, the segmented detector can include, for example, two or more concentrically arranged segments. For example, Figure 3D the segmented detector 344d can include two segments 350d and 351d arranged around the central aperture 345. The segmented detector 344d can represent a two-channel detector with a different geometry from the two-channel detector 344b. The two segments can be separated by non-sensitive material 302 (such as the substrate used for detector 344d). Each segment 350d and 351d can form a separate imaging channel and be coupled to a separate detection output. Alternatively, the detector 344d can include more than two concentric imaging channels. For example, the detector 344d can include three, four, five, or more concentric imaging channels.

[0073] More information about monolithic and segmented detectors can be found in U.S. Patent Publication No. 2021 / 0319977, which is incorporated herein by reference in its entirety.

[0074] Figure 4 Illustrates an exemplary relationship between the probe spot of the primary beam scan in the sample field of view FOV and the corresponding distribution of electron landing positions on the region 447 of the detector 444. As Figure 4As illustrated by the horizontal arrow in the FOV, the primary beam can be deflected to scan the probe spot along, for example, a series of parallel scan lines. Although the field of view FOV shows a conventional raster scan profile, it should be understood that other scan profiles can be used, such as conventional or improved serpentine scans or improved raster scan profiles, etc.

[0075] Each discrete position (where the probe spot is scanned) can generate emitted electrons (such as secondary electrons or backscattered electrons), which can impinge on the detector 444 as a cluster of electron landing positions. In some embodiments, each individual cluster of electron landing positions can represent, for example, a pixel in the generated image. Thus, the corresponding spot on the sample surface can be referred to as a sample pixel.

[0076] In Figure 4 FIG. 8, five such sample pixels 1-5 are depicted in the FOV, as well as their corresponding clusters of electron landing positions in the region 447 of the detector 444. The number and size of the depicted sample pixels are given for illustrative purposes only. For example, the FOV can be substantially covered by such sample pixels, and the detector surface near the region 447 can be substantially covered by overlapping clusters of electron landing positions. When the probe spot irradiates the upper left corner at position 1 in the FOV, the cluster of electron landing positions can be centered at the corresponding corner at position 1 in the region 447. The same is true for positions 2, 4, and 5. When the probe spot irradiates the central position at position 3 in the FOV, the cluster of electron landing positions can be centered at position 3 in the region 447. In this way, for example, scanning a square-shaped FOV on the sample surface may result in a substantially square-shaped distribution of electron landing positions on the detector. It should be understood that the actual spatial relationships may be different from the schematic depiction shown. For example, the cluster of electron landing positions traced on the region 447 may be opposite, diagonally opposite, etc. to its corresponding probe spot in the FOV.

[0077] The landing positions of the emitted electrons can be substantially clustered within a region having a radius of, for example, one millimeter or several millimeters or more. In addition to the central position varying with the deflection angle of the primary beam, other parameters can also affect the distribution of the electron landing positions. For example, due to reasons such as the initial kinetic energy and emission angle of the electrons, the electrons have different trajectories, and thus the geometric spread of the landing positions of the emitted electrons may vary. Additionally, the central position and geometric spread of the clusters of electron landing positions on the detector surface can vary based on the conditions of the charged particle beam device (such as Figures 2A - 2C charged particle beam devices 100A, 100B, or 100C) of

[0078] As Figure 4As can be seen, the size, shape, and position of the area on the detector surface that receives electrons can be related to the size, shape, and relative position of the FOV on the sample surface and the conditions of the charged particle beam apparatus. Thus, for a given FOV exposure, the entire detector surface may not be required. In conventional detectors (such as, for example, the detectors 344a-d described above) Figures 3A - 3D even when charged particle beam process parameters (such as FOV size, landing energy, aperture size, beam current, lens / deflector settings, image compensation unit (ICU) tilt angle settings, etc.) change, the size of the detection surface utilized can remain fixed.

[0079] Using such a large detection surface can allow for high electron collection and easier alignment, but can also result in reduced detection sensitivity and higher noise. For example, detector noise may increase due to parasitic capacitance within the detection system. Figure 5 An exemplary circuit diagram is shown that illustrates various elements that can contribute to noise in a single imaging channel of a charged particle detector. For example, in a monolithic detector, the circuit diagram can represent the noise of the entire detector. In a dual-channel detector (such as, for example Figure 3B the detector 344b), the circuit diagram can represent the noise from one of the semicircular imaging channels 350b or 351b. The noise i EQ can be expressed as:

[0080]

[0081] where i B is the electron beam spot noise, represents the thermal noise of the feedback transistor, is the reference voltage noise at the non-inverting point of the preamplifier, and represents the capacitive induction noise in the imaging channel. Within this final term, the capacitance C S can include multiple components, such as the common-mode amplifier circuit capacitance C CM the differential-mode amplifier circuit capacitance C DIFF and the detector junction capacitance C D . Among these components, the junction capacitance C D can represent a relatively large contribution to the total capacitive induction noise. For example, in an exemplary case where the common-mode amplifier circuit capacitance C CM and the differential-mode amplifier circuit capacitance C DIFF each contribute approximately 20 - 25 pF, the junction capacitance C D in a conventional single-channel detector can contribute, for example, 150 pF or more.

[0082] The size of the detector surface can be related to the total junction capacitance C DThere is a direct relationship. However, as discussed above, even if the area of use of the detector (e.g., the area on which the incident electrons are emitted) changes, some detectors may have a fixed detection area. For example, the area of use of the detector can change due to changes in the FOV size, beam aperture setting, landing energy, lens / deflector setting, ICU tilt angle setting, or other parameters. Therefore, such a detector can have a high noise penalty and cannot be reduced even when, for example, detecting a small area or using a low landing energy. In addition, even if the detection area can be changed by, for example, excluding at least one imaging channel of a multi-channel segmented detector, the detector segments may not have dimensions, shapes, or positions corresponding to the size, shape, or position of the FOV. Therefore, it may be difficult to change the effective detection area while maintaining a high electron collection efficiency.

[0083] Figures 6A - 6D FIG. illustrates an example of a segmented charged particle detector 644 consistent with an embodiment of the present disclosure. The charged particle detector 644 can be, for example, a detector configured to be used in a SEM or other electron beam device (such as a device according to Figure 1 , Figure 2A , Figure 2B or Figure 2C ). The charged particle detector 644 can include a first segment 650, a second segment 651, a third segment 652, and a fourth segment 653. The first segment 650 can be coupled to a first detection output 650.1, the second segment 651 can be coupled to a second detection output 651.1, the third segment 652 can be coupled to a third detection output 652.1, and the fourth segment 653 can be coupled to a fourth detection output 653.1. The charged particle detector 644 can include an aperture 645 configured to allow an electron beam (e.g., a primary electron beam or a beam wave) to pass through the detector and impinge on the sample surface. Alternatively, the charged particle detector 644 can be configured to be positioned away from the primary beam axis and may not include an aperture 645.

[0084] As Figure 6A shown, the first segment 650 can be offset from the center of the detector 644 such that the aperture 645 is positioned away from the first segment 650. The charged particle detector 644 can include diodes (such as PIN diodes), scintillators, radiation detectors, and solid-state detectors, as well as other charged particle sensing devices. The segments 650 - 653 of the charged particle detector 644 can be separated by non-sensitive material 602.

[0085] The first detector region of detector 644 may include a first segment 650. The second detector region may include the first segment 650 and a second segment 651, and the second segment 651 may partially or completely surround the first segment 650. For example, the second segment 651 may completely surround the first segment 650, as seen in Figure 6A or Figure 6B as seen therein. Alternatively, the second segment 651 may abut the first segment 650 on, for example, both sides, such as seen in Figure 6C as seen therein. The second segment 651 may surround at least 50% or at least 75% of the boundary of the first segment 650. For example, the first segment 650 may be offset from the center of detector 644 such that a portion of the first segment 650 substantially forms the outer boundary of the entire detector surface. In such a case, the second segment 651 may only abut the first segment 650 on two or three sides and may thus only surround approximately 50% or 75% of the boundary of the first segment 650. As another example, the first segment 650 may abut the second segment 651 on a portion of its boundary and may abut another segment (such as a third segment 652 or a fourth segment 653) on the remaining portion of its boundary, such as seen in Figure 6D as seen therein. Generally, the second segment 651 may be arranged to form, in combination with the first segment 650, the second detector region.

[0086] The segments of detector 644 may be shaped to create a detector region corresponding to the typical shape of the FOV to be scanned. For example, for a device that may scan an FOV having, for example, a rectangular or square shape, the first detector region or the second detector may have a rectangle-based shape corresponding to the FOV shape. For example, the rectangle-based shape may be substantially square, substantially rectangular, or may be a shape that matches the expected electron distribution of a substantially square or substantially rectangular FOV. The first detector region or the second detector may have a shape with three flat sides and one curved side, as seen in the second detector region formed by the boundary of the second segment 651 in Figure 6A as seen therein. Alternatively, the first detector region or the second detector may have a shape as seen in Figure 6BIn some embodiments of the present disclosure, the sides of the first segment may be, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or larger. In some embodiments of the present disclosure, the outer sides of the second segment may be, for example, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 12 mm, 15 mm or larger. Other FOV shapes are also possible. Therefore, in some embodiments of the present disclosure, other shapes of the first detector area and the second detector area are also contemplated. In some embodiments, the shape of the segment or detector area can be designed to match the shape of the charged particle landing distribution (which is associated with the FOV) rather than the shape of the FOV itself. For example, if a square FOV is expected to produce a distribution similar to a distorted square on the detector surface (such as by a pillow or barrel distortion), the segment or detector area can be shaped according to the shape of the pillow or barrel distortion.

[0087] The first detector region may have lower noise than the second detector region. For example, since the first detector region may include only the first segment 650, the first detector region may have a smaller surface area than the second detector region. This smaller surface area may result in a higher junction capacitance C of the first detector region. D is smaller, which can result in lower noise (e.g., as described above in Equations 1 and Figure 5 The lower noise value i discussed in EQ ). Since the second region adds additional junction capacitance from the second segment 651, the second region may have a higher noise value than the first region. However, the added size of the second region may allow for greater electron collection.

[0088] Thus, detector 644 may allow a trade-off between noise and collection rate to be selected depending on the parameters of a particular charged particle beam exposure. Figures 1 - 2C The apparatus 100, 100A, 100B or 100C in any one of the embodiments) can scan a FOV on a sample surface and generate an image based on signals from, for example, one of a first detector region and a second detector region. The image generated based on the signal from the first detector region can have lower image channel noise, resulting in higher image accuracy. For example, the signal from the first detector region can have a lower electron root mean square (rms) value than the signal from the second detector region. Alternatively, an image generated based on the signal from the second detector region can be more preferred, given the higher available collection surface.

[0089] For example, a first charged particle beam exposure (such as, for example Figures 1 - 2CThe electron beam exposure in the apparatuses 100, 100A, 100B, or 100C may include first exposure parameters that cause a first portion of the charged particle landing positions to be included within a first detector region on the first section 650. The first exposure parameters may include, for example, a first FOV size on the sample surface, a first landing energy, a first beam aperture setting, a first beam current, a first lens / deflector setting, a first ICU tilt angle setting, or other parameters that may affect the distribution of charged particle landing positions on the surface of the detector 644. The first portion may include, for example, 90% or more of the charged particle landing positions on the detector. In some embodiments, a larger portion may include, for example, 95%, 99%, 99.5%, 99.9%, or 99.99% of the charged particle landing positions on the detector. The first charged particle beam exposure may include a first noise value in the first detector region.

[0090] The second charged particle beam exposure may include second exposure parameters that cause a second portion of the charged particle landing positions to be included within a second detector region on the first section 650 and the second section 651. The first exposure parameters and the second exposure parameters may include, for example, different values of the same parameter. For example, the first exposure parameter may include a first FOV size, and the second parameter may include a second FOV size that is larger than the first FOV size. The second charged particle beam exposure may include a second noise value in the second detector region. The second noise value may be higher than the first noise value.

[0091] In some embodiments, the first charged particle beam exposure and the second charged particle beam may not be performed simultaneously. In some embodiments, the first portion and the second portion of the charged particle landing positions may be, for example, substantially equal. For example, the first charged particle beam exposure may include a first FOV size on the sample surface. The first FOV size may cause a first portion (e.g., >95%) of the charged particle landing positions to be included within the first detector region on the first section 650. The second charged particle beam exposure may include a second FOV size on the sample surface, and the second FOV size is larger than the first FOV size. The second FOV size may cause a second portion (e.g., also >95%) of the charged particle landing positions to be included within the second detector region on the first section 650 and the second section 651. Alternatively, the second portion may be larger than the first portion.

[0092] In some embodiments, the first charged particle beam exposure and the second charged particle beam can be performed simultaneously. In some embodiments, the first and second portions of the charged particle landing positions can be different. For example, the charged particle beam exposure can include a first portion (e.g., >95%) of the charged particle landing position that is contained within a first detector region on the first segment 650, and a second portion (e.g., >99%) of the charged particle landing position that is contained within a second detector region on the first segment 650 and the second segment 651. The charged particle beam exposure can include a first noise level in the first detector region and a second noise level in the second detector region. In some embodiments, for example, considering the lower noise value in the first detector region, the operator can utilize the first detection signal from the first detector region. In some embodiments, for example, considering the higher collection rate in the second detector region, the operator can utilize the second detection signal from the second detector region. The second signal can include the first detection signal from the first segment 650 and another detection signal from the second segment 651. In some embodiments, the second detection signal can include a weighted average or other mathematical combination of the first detection signal and the other detection signal.

[0093] The first detection signal from the first detector region can be used to generate a first image of the sample with a first accuracy. The second detection signal from the second detector region can be used to generate a second image of the sample with a second accuracy. The first accuracy can be higher than the second accuracy.

[0094] The charged particle detector 644 can include additional detector regions. For example, the charged particle detector can include a third detector region corresponding to the third segment 652 and a fourth detector region corresponding to the fourth segment 653. In some embodiments, the signals from the third and fourth detector regions can be used, for example, to monitor beam alignment. In some embodiments, the charged particle detector can include a fifth detector region that includes all four segments. For example, the fifth detector region can be used to optimally collect the charged particle landing positions on the detector surface.

[0095] Although Figures 6A - 6D Four segments 650 - 653 are illustrated, embodiments of the present disclosure are not limited thereto. For example, the detector surface can include more than two nested detector segments, resulting in a greater number of optional detector regions. For example, smaller segments can exist within the first segment 650, or larger detector segments can exist around the second segment 651, and for example, be located between the second segment 651 and the third segment 652 and the fourth segment 653.

[0096] Figures 7A - 7CIllustrated is an example of the distribution of charged particle landing positions on detector 744 in accordance with an embodiment of the present disclosure. Detector 744 can be, for example, Figures 6A - 6D the detector 644 in Figure 7A As seen in Figures 7B - 7C (corresponding markings are omitted in Figures 6A - 6D ), detector 744 can include, for example, four segments 750 - 753, similar to

[0097] Figure 7A Illustrated is a first distribution of charged particle landing positions. The first distribution can correspond to a first charged particle beam exposure that includes, for example, a first value of exposure parameters. The exposure parameters can include, for example, FOV size, beam aperture setting, landing energy, lens / deflector setting, ICU tilt angle setting, or other parameters. Similarly, Figure 7B and Figure 7C can respectively illustrate a second distribution and a third distribution of charged particle landing positions, where the second distribution corresponds to a second charged particle beam exposure that includes a second value of exposure parameters, and the third distribution corresponds to a third charged particle beam exposure that includes a third value of exposure parameters. For example, Figures 7A - 7C 's distributions can respectively correspond to three distributions of charged particle landing positions at low, medium, and high landing energy settings. As seen in Figure 7A , the first detector region including segment 750 can capture a larger portion of the charged particle landing positions at low landing energy settings. Thus, the first detector region with lower noise may be ideal for use with the first exposure. In Figure 7B , the first detector region may not capture a sufficient portion of the charged particle landing positions at medium landing energy settings. However, the second detector region including the first segment 750 and the second segment 751 can capture a sufficient portion with a higher noise penalty. Thus, one of the first detector region and the second detector region may be well-suited for the second exposure. For example, the first detector region may be preferred due to lower noise, or the second detector region may be preferred due to a higher collection rate. In Figure 7C , at higher landing energy settings, there may be a large amount of electron distribution outside the second detector region. In such a case, the second detector region can achieve an appropriate balance between noise and collection rate. Alternatively, a larger detector region, such as the fifth detector region discussed above, which includes all four segments of detector 744, can be employed.

[0098] Figure 8 is a flowchart illustrating a charged particle detection method 800 in accordance with an embodiment of the present disclosure. Method 800 can use a charged particle beam apparatus (such as Figures 1 - 2Cby an electron beam tool 100, 100A, 100B, or 100C). A charged particle detector (such as Figures 6A - 6D detector 644 of Figures 7A - 7C detector 744) can be operated according to method 800. The method can be performed by a controller (such as controller 109 or image processing system 199).

[0099] At step 801, a first exposure can be detected on a first detector region of the detector. The first exposure can include a charged particle beam process in which a primary charged particle beam exposes a surface of a sample, generating emitted charged particles from the sample that are detected at the detector surface to generate a first signal. For example, the first exposure can include an SEM scan or other electron beam tool process. The first exposure can be performed under a first exposure setting. For example, the first exposure setting can include a first FOV size, a first landing energy, a first beam aperture setting, a first beam current, a first lens / deflector setting, a first ICU tilt angle setting, or other parameters that can affect the distribution of charged particle landing positions on the detector surface. The first detector region can include, for example, a first segment of segmented charged particles. The first detector region can include a first noise parameter. For example, the first noise parameter can include a capacitance value (such as a junction capacitance) of the first segment.

[0100] At step 802, a second exposure can be detected on a second detector region of the detector. The second exposure can include, for example, a process similar to the first exposure, which can be detected at the second detector region to generate a second signal. The second exposure can be performed under a second exposure setting. For example, the second exposure setting can include a second FOV size, a second landing energy, a second beam aperture setting, a second beam current, a second lens / deflector setting, a second ICU tilt angle setting, or other parameters that can affect the distribution of charged particle landing positions on the detector surface. In some embodiments, the second exposure can be performed under the first exposure setting.

[0101] The first exposure and the second exposure can occur simultaneously or at different times. For example, the first exposure and the second exposure can include a single scan, where the first exposure refers to the portion of the scan that occurs on a first smaller FOV, and the second exposure refers to the portion of the scan that occurs on a second larger FOV. The first FOV and the second FOV can overlap. Alternatively, the first FOV and the second FOV can be located on different portions of the same or different sample surfaces.

[0102] The second detector region may include, for example, a first segment and a second segment of a segmented charged particle detector. The second segment may be arranged to form the second detector region in combination with the first segment. In some embodiments, the second segment may surround the first segment. The second detector region may include a second noise parameter. For example, the second noise parameter may include capacitance values (such as junction capacitance) of the first segment and the second segment.

[0103] At steps 803 and 804, a first image may be generated based on a first signal detected at the first detector region and a second image may be generated based on a second signal detected at the second detector region, respectively. The first image may have a higher accuracy than the second image. For example, given that the junction capacitance in the first detector region is lower than that in the second detector region, the first signal may have a lower SNR ratio. Alternatively, the second image may be preferred given a higher collection rate of charged particles on the surface of the second detector region. A synthetic image may be generated based on the first image and the second image. In some embodiments, the second image may provide baseline information for monitoring the first image. For example, since the first detector region is relatively small, misalignment may result in fewer charged particles incident on the first detector region, thereby degrading the first image. The second image may be used to monitor or correct such a situation.

[0104] Method 800 may be used to generate an optimal image in each FOV of the sample surface. The method may be used to generate an optimal image of a full scan of the sample surface. The full scan may include, for example, a synthesis of a first image from the first detector region and a second image from the second detector region.

[0105] Additional images may be generated while generating the first image and the second image according to method 800. For example, the full detector surface (such as having segments 650 - 653) may be used to generate an image at the maximum collection rate.

[0106] Figure 9 is a flowchart illustrating a charged particle detection method 900 consistent with embodiments of the present disclosure. Method 900 may be performed using a charged particle beam apparatus (such as Figures 1 - 2C the electron beam tools 100, 100A, 100B, or 100C in Figures 6A - 6D the detector 644 in Figures 7A - 7C or the detector 744 in

[0107] At step 901, exposure settings can be selected for a charged particle beam exposure process. The exposure process can be an electron beam exposure or other charged particle exposure, e.g., in any one of apparatuses 100, 100A, 100B, or 100C in Figures 1 - 2C . The apparatus can also include a charged particle detector having a first detector region and a second detector region. For example, the detector can be detector 644 in Figures 6A - 6D or detector 744 in Figures 7A - 7C . The exposure settings can include parameters that affect the spatial distribution of charged particles reaching the detector surface. For example, the parameter can include FOV size, landing energy, aperture size, beam current, lens / deflector settings, ICU tilt angle settings, or other parameters that affect the spatial distribution. The exposure settings can be adjustable parameters or fixed parameters. In the latter case, the step of selecting the exposure settings can be performed when designing the exposure apparatus.

[0108] At step 902, a detector region of the detector can be selected based on the exposure settings selected at step 901. For example, it can be determined that, based on the selected exposure settings, a sufficient portion (e.g., a predetermined percentage, such as 90%, 95%, 99%, 99.5%, 99.9%, or 99.99%) of the emitted charged particles from the sample surface will be collected at the first detector region. In this case, the first detector region can be selected for imaging. Alternatively, it can be determined that a higher collection rate may be required. In this case, the second detector region can be selected. The second detector region can include the first detector region and another region outside the first detector region.

[0109] At step 903, a charged particle exposure process can be performed using the apparatus as discussed at step 901. The charged particle exposure process can include the selected exposure settings. Detection can be performed at the selected detector region as discussed at step 902 to generate a detection signal at the selected detector region. The detection can generate a detection signal having a preferred balance between SNR and collection rate.

[0110] At step 904, an image can be generated based on the detection signal from the detector. For a given exposure setting, the image can have a higher accuracy than an image generated based on a signal from another detector region of the detector.

[0111] The steps illustrated above in methods 800 and 900 need not be performed in the order presented, and may be performed simultaneously, or in an order different from the order presented above. For example, step 802 may be performed before step 801 or simultaneously with step 801. Step 902 may be performed after step 903 or step 904 or simultaneously with step 903 or step 904.

[0112] Figures 10A - 10C FIG. shows a cross-sectional view of a portion of a charged particle detector 1044 according to some embodiments of the present disclosure. The charged particle detector 1044 may be, for example, an electron detector configured to be used in an SEM or other electron beam device (such as a device according to Figures 1 - 2C ). As shown on the left side, the charged particle detector 1044 may include a segmented detector, as discussed above with respect to Figure 10A . The detector 1044 may include, for example, a PIN diode type charged particle detector. The diameter of the detector 1044 may be, for example, about 20 millimeters (mm). The detector 1044 may include an aperture 1045, the diameter of which is, for example, between about 2 - 4 mm, through which the primary charged particle beam 1005 passes (such as, for example, Figures 6A - 6D 145 in Figure 2C or Figures 6A - 6D 645 in

[0113] As shown in Figure 10A , the detector 1044 may include a top conductive layer 1061 at the front surface (e.g., the surface facing the sample and configured to receive the emitted charged particles), and a bottom conductive layer 1065 on the back surface (i.e., the surface not facing the sample and not configured to receive the emitted charged particles). The top conductive layer 1061 may include, for example, an aluminum layer. The top conductive layer 1061 may improve the series resistance and reflect any stray light (e.g., light from a laser and scattered inside the column of the SEM system). The top conductive layer 1061 may be configured as the electron incident surface. The top conductive layer 1061 may form the sensor surface of the detector 1044. The top conductive layer 1601 may include the top electrode of the detector 1044. The bottom conductive layer 1065 may include, for example, a titanium gold layer. For example, the bottom conductive layer 1065 may include the bottom electrode of the detector 1044.

[0114] Detector 1044 may include a semiconductor region 1060 between a top conductive layer 1061 and a bottom conductive layer 1065. The semiconductor region 1060 may include, for example, a p+ region 1062, an intrinsic region 1063, and an n+ region 1064. The intrinsic region 1063 may include a silicon layer, and the p+ region 1062 and the n+ region 1064 may include a p-doped region and an n-doped region on silicon. The p+ region may include a p-type dopant such as boron. The n+ region may include an n-type dopant such as one or more of arsenic, phosphorus, or antimony. The p+ region 1062 and the n+ region 1064 may form the terminals of a PIN diode. Alternatively, region 1062 may include an n+ region and region 1064 may include a p+ region.

[0115] In operation, detector 1044 may provide the function of generating an electrical signal in response to an incident charged particle event. Incoming charged particles (such as emitted electrons 1071 from a sample (such as Figure 10B sample 1050 in)) may pass through the top conductive layer 1061 and may enter the depletion region in the intrinsic region 1063. The incoming electrons may interact with the material of the intrinsic region 1063 and may generate electron-hole charge carrier pairs. The electrons and holes of the generated electron-hole pairs may be directed by an internal electric field in detector 1044 towards the p+ region 1062 and the n+ region 1040, and are collected at the top and bottom electrodes, thereby generating a current indicative of the incident charged particle event.

[0116] A "dead zone" or insensitive region 1002 may surround an aperture 1045 at the front surface of detector 1044. The insensitive region 1002 may include, for example, a SiO2 layer, or another oxide or non-conductive material layer. One issue that has a direct impact on the performance of a charged particle detector is the spatial extent of the insensitive region 1002 around the aperture 1045. Ideally, this insensitive region 1002 should be as small as possible because in some cases, the emitted electron 1071 distribution may be highly concentrated around the aperture 1045 (e.g., see Figure 2C the emitted electron 171 distribution around hole 145 in). Thus, for most cases where emitted electrons reach the center of detector 1044, the proportion of detected electrons will decrease as the size of the insensitive region 1002 increases. Thus, it may be desirable to minimize any "dead zones" in detector 1044 to improve its overall efficiency or sensitivity. However, one limitation in reducing this "dead zone" is the lateral extent of the deep depletion region required for a fast detection response (e.g., due to reduced junction capacitance). For example, if the depletion layer does not reach the surface or sidewall 1055 adjacent to the aperture 1045, it may be desirable to prevent a significant increase in leakage current in the image channel of the detection segment closest to the aperture 1045.

[0117] Another problem faced by charged particle detectors is the accumulation of charge on the detector surface. For example, as Figure 10A seen, some high-energy emitted electrons 1071 may strike a non-conductive or low-conductivity surface (such as non-sensitive area 1002 or sidewall 1055). In some cases, the high-energy electrons may cause more electrons to be emitted than deposited, resulting in the accumulation of a net positive charge at the surface. This can increase the noise in the image channel and create an asymmetry in the electric field near the path of the primary charged particle beam 1005, leading to beam deflection, image aberration, and other errors. To reduce these effects, the charged particle detector 1044 may be provided with a layer of conductive material along the sidewall 1055 adjacent to the aperture 1045. For example, the Ti / Au material of the bottom conductive layer 1065 may be extended upward along the sidewall 1055 to another n+ region 1064a to smooth the charge imbalance along the sidewall 1055. However, as Figure 10A illustrated in the close-up view of the sidewall 1055 in, there is a problem. Due to the surface roughness and manufacturing defects of the intrinsic region 1063, the bottom conductive layer 1065 may exhibit non-uniformity along the sidewall 1055. This may result in variations in the thickness of the exposed portion of the intrinsic region 1063 as well as the Ti / Au material. Therefore, the asymmetry in the electric field near the path of the primary charged particle beam 1005 may persist. Additionally, since another n+ region 1064a is close to the p+ region 1060, a high leakage current may be caused.

[0118] Another way to minimize the above problems (as Figure 10B shown) may include extending the doping profile of the n+ region 1064 from the back surface of the detector 1044 along the sidewall 1055 until the front surface of the non-sensitive area 1002. Although this can further reduce the electric field asymmetry within the aperture 1045, it cannot solve the problem of leakage current. And it cannot solve the charge accumulation that occurs at the non-sensitive area 1002, or the corresponding reduction in efficiency and sensitivity. These problems may be particularly problematic when the ICU is not in use.

[0119] For example, Figure 10C schematically illustrates the relationship between the sample 1050, a cross-sectional portion of the detector 1044, and the ICU 1066. The ICU 1066 may be configured to impart an inclination angle to the emitted electrons 1071. The ICU 1066 may include, for example, a plurality of coils through which a high current is generated. In this way, the emitted electrons can be steered away from the center of the aperture 1045, so that more electrons land on the detection surface. For example, in Figure 10CIn the plane of, the ICU 1066 can deflect the first emitted electron 1071a and the second emitted electron 1071b away from the aperture 1045, such that a greater number of the emitted electrons land on the detection surface of the top conductive layer 1061. In the absence of the ICU 1066, most of the emitted electrons may be emitted with such a low divergence that they return directly through the aperture 1045 (as shown by the emitted electron 171c), or a greater number of the electrons may strike the non-sensitive area 1002, thus greatly reducing the collection efficiency and increasing the charge induction noise. However, due to the field created by the high current within its coil, the ICU may generate noise and other aberrations of its own. Thus, it may be desirable to eliminate the ICU while maximizing the collection efficiency and minimizing the noise and other charging effects.

[0120] Embodiments of the present disclosure provide a charged particle detector that can maximize the charged particle collection efficiency while minimizing unwanted charging effects. The charged particle detector according to embodiments of the present disclosure can allow the elimination of the ICU from the charged particle device, thus further reducing the noise and improving the image quality. Figures 11A - 11B A cross-sectional view of a portion of a charged particle detector 1144 consistent with an embodiment of the present disclosure is illustrated. Except as described below, the charged particle detector 1144 can be similar to, for example, the charged particle detector 1044.

[0121] As Figure 11A shown, the charged particle detector 1144 can include a top conductive layer 1161, a semiconductor region 1160, a bottom conductive layer 1165, and a non-sensitive area 1102. The semiconductor region 1160 can include, for example, a first doped region 1162, an intrinsic region 1163, and a second doped region 1164. As illustrated, the first doped region 1162 can include a p+ region, while the second doped region 1164 can include an n+ region. However, in some embodiments, the first doped region 1162 can include an n+ region, while the second doped region 1164 can include a p+ region. Generally, the first doped region 1162 can have a different conductivity type from the second doped region 1164. For example, if one doped region is of the n-doped type (e.g., n, n+, or n++), then the other doped region can be of the p-doped type (e.g., p, p+, or p++ type). The first doped region 1162 can extend from the front surface (detection surface) of the semiconductor region 1060 to the sidewall 1155 adjacent to the aperture 1145. The first doped region 1162 can extend along the sidewall 1155 adjacent to the aperture 1145 to the non-sensitive area 1102, which includes, for example, a SiO2 layer or other material layer as discussed above. The top conductive layer 1161 can extend to the edge 1167 of the aperture 1145, as Figure 11Aas illustrated in. Alternatively, as Figure 11B shown in, the top conductive layer 1161 may extend along the sidewall 1155 adjacent to the aperture 1145 to improve the series resistance there. Using Figure 11A or Figure 11B arrangements, a "dead zone" required to maintain a large depletion region between the first doped region 1162 and the second doped region 1164 can be achieved at the back surface (non-detection surface) of the detector 1144. For example, the non-sensitive region 1102 may extend from the first doped region 1162 and may contact at least one of the second doped region 1164 or the bottom conductive layer 1165. Figures 11A - 11B arrangements can bring many advantages to collection efficiency, detector speed, imaging performance, and noise reduction.

[0122] For example, by repositioning the non-sensitive region 1102 to the back surface, the detection surface on the front side of the detector 1144 can precisely increase the area that can receive the highest concentration of emitted electrons 1171, thus greatly improving the collection efficiency. For example, as Figures 11A - 11B seen in, the detection surface may extend to the edge 1167 of the aperture 1145 itself (such as the entire perimeter of the edge 1167 of the aperture 1145). Thus, within the central region of the detector 1144, electrons emitted to any part of the front surface can be collected. At the same time, given the fact that the non-sensitive region 1102 is not irradiated, charging errors can be reduced. Therefore, moving the non-sensitive region 1102 to the back surface can not only improve the collection efficiency but also reduce noise, beam shift, and other charging effects.

[0123] In addition, given that the first doped region 1162 is extended along the sidewall 1155 adjacent to the aperture 1145, the collection efficiency can be improved. This creates another detection surface on the sidewall 1155. Thus, even if the emitted electrons 1171 transmitted into the aperture 1145 strike on the sidewall 1155, they can be collected. At the same time, the doped surface of the sidewall 1155 can serve to prevent charge accumulation, thereby reducing the asymmetry in the electric field. Therefore, beam shift, aberration, and other imaging errors can be further improved while further increasing the collection efficiency.

[0124] In some embodiments, compared with, for example Figures 10A - 10CCompared with the aperture 1045, the detection area can be further increased by reducing the diameter of the aperture 1145. For example, while the diameter of the aperture 1045 can be, for example, 2 - 4 mm, the diameter of the aperture 1145 can be, for example, 200 - 400 μm. This feature can also be used for several purposes. First, as already mentioned, the effective detection surface area on the front surface of the detector 1144 can be increased by reducing the aperture diameter. Second, the reduced aperture diameter and the additional sidewall detection surface can render the ICU unnecessary. For example, it may no longer be necessary to tilt the emitted electrons 1171 away from the center of the detector 1144 because relatively few emitted electrons will enter the aperture 1145 and even fewer will exit. Instead, most of the emitted electrons 1171 can be received at the front surface of the top conductive layer 1161 or on the sidewall 1155. Therefore, the ICU can be discarded, thus eliminating a strong noise source.

[0125] Both the reduction of the aperture 1145 and the repositioning of the insensitive region 1102 provide additional degrees of freedom to optimize the lateral extent of the depletion region between the first doped region 1162 and the second doped region 1164. By comparing Figures 10A - 10B a bird's-eye view of the detector 1044 on the left with Figures 11A - 11B a bird's-eye view of the detector 1144 on the left, this can be most easily understood. In the detector 1044, the design of the outer diameter of the insensitive region 1002 may be constrained by the need to maintain a small dead zone. At the same time, the design of the inner diameter of the insensitive region 1002 may be constrained by the need to provide a sufficiently large aperture size to minimize the effect of the electric field asymmetry on the primary charged particle beam 1005. Therefore, the maximum size of the depletion region between another n+ region 1064a and the p+ region 1062 is limited. This may lead to an increase in the junction capacitance, a slower detection response, and a higher leakage current. However, the insensitive region 1102 in the detector 1144 is not subject to this limitation. For example, as discussed above, by providing the first doped region 1162 along the sidewall 1155, the diameter of the aperture 1145 can be reduced without introducing an unacceptable asymmetry in the electric field at the primary charged particle beam 1105. Therefore, even for an insensitive region 1102 with a diameter exactly the same as that of the insensitive region 1002, the separation distance between the first doped region and the second doped region can be increased. However, since the insensitive region 1102 is located on the back surface of the detector 1144, its size can be increased without losing the detection surface area or increasing the charging effect. In addition, as Figures 11A - 11BAs can be seen, for example, by spanning adjacent detector segments, the non-sensitive region 1102 can overlap with other top-side boundaries without creating any substantial design complexity. Thus, the non-sensitive region 1102 can be made larger to achieve reduced junction capacitance, faster detection response, and lower leakage current. For example, even when the diameter of the aperture 1145 is between, say, 200 μm and 1 mm, the outer diameter of the non-sensitive region 1102 can be, say, 4 mm, 6 mm, or 8 mm.

[0126] In addition, while the cross-sectional structure near the detector aperture has been disclosed for, e.g., Figures 6A - 6D segmented detectors, embodiments of the present disclosure are not limited thereto. For example, in some embodiments, Figures 10A - 11B the cross-sectional configuration of Figures 3A - 3D can be arranged in other detectors, such as

[0127] monolithic or segmented surface detectors, pixelated segment arrays, or other detector arrangements of the type shown in

[0128] 1. A segmented multi-channel detector, comprising:

[0129] a first detector region having a first segment; and

[0130] a second detector region having a first segment and a second segment, the second segment surrounding at least 50% of the first segment, wherein

[0131] the first detector region includes a first noise value of a noise parameter; and

[0132] the second detector region includes a second noise value of the noise parameter, the second noise value being higher than the first noise value.

[0133] 2. The segmented multi-channel detector according to clause 1, wherein the noise parameter is capacitance.

[0134] 3. The segmented multi-channel detector according to clause 1, wherein the noise parameter is junction capacitance.

[0135] 4. The segmented multi-channel detector according to clause 1, wherein the second segment completely surrounds the first segment.

[0136] 5. The segmented multi-channel detector according to clause 1, wherein the first segment has a rectangle-based shape.

[0137] 6. The segmented multi-channel detector according to clause 4, wherein the rectangle-based shape is a square-based shape.

[0138] 7. The segmented multi-channel detector according to clause 1, wherein the dimension of the first segment in the first direction is at least 1 mm.

[0139] 8. The segmented multi-channel detector according to clause 1, wherein:

[0140] The shape of the first detector region corresponds to the shape of the first FOV on the sample surface in the charged particle beam device.

[0141] 9. The segmented multi-channel detector according to clause 8, wherein:

[0142] The shape of the second detector region corresponds to the shape of the second FOV on the sample surface in the charged particle beam device, and the second FOV is larger than the first FOV.

[0143] 10. The segmented multi-channel detector according to clause 1, further comprising:

[0144] A third segment, at least bordering on the first side of the second detector region; and

[0145] A fourth segment, at least bordering on the second side of the second detector region, and the second side is opposite to the first side.

[0146] 11. The segmented multi-channel detector according to clause 1, further comprising an aperture located outside the first segment.

[0147] 12. The segmented multi-channel detector according to clause 9, wherein the aperture is located in the second segment.

[0148] 13. A charged particle beam device, comprising:

[0149] A charged particle beam source configured to generate a primary charged particle beam;

[0150] A charged particle optical system configured to scan the primary charged particle beam over a field of view (FOV) on the sample surface; and

[0151] The segmented multi-channel detector according to clause 1.

[0152] 14. The charged particle beam device according to clause 13, wherein:

[0153] The shape of the first detector region corresponds to the shape of the FOV on the sample surface.

[0154] 15. The charged particle beam device according to clause 13, wherein:

[0155] The shape of the second detector region corresponds to the shape of the FOV on the sample surface.

[0156] 16. The charged particle beam device according to clause 13, wherein:

[0157] The first detector region is configured to capture more than 90% of the emitted charged particles from the scanning of the beam over the FOV on the sample surface.

[0158] 17. The charged particle beam device according to clause 13, wherein:

[0159] The second detector region is configured to capture more than 90% of the emitted charged particles from the scanning of the beam over the FOV on the sample surface.

[0160] 18. A method for detecting charged particle events in a charged particle detector, comprising:

[0161] Performing a first scan of the sample surface with a charged particle beam at a first exposure setting so that the emitted charged particles from the sample surface land in a first detector region of the charged particle detector, the first detector region including a first noise value of a noise parameter;

[0162] Generating a first image based on the first scan;

[0163] Performing a second scan of the sample surface with a charged particle beam at a second exposure setting so that the emitted charged particles from the sample surface land in a second detector region of the charged particle detector, the second detector region including a second noise value of the noise parameter, the second noise value being higher than the first noise value; and

[0164] Generating a second image based on the second scan, the first image having a higher accuracy than the accuracy of the second image, wherein

[0165] The first detector region includes a first section of the charged particle detector;

[0166] The second detector region includes the first section and a second section of the charged particle detector; and

[0167] The second detector region is larger than the first detector region.

[0168] 19. The method according to clause 18, wherein the noise parameter is capacitance.

[0169] 20. The method according to clause 18, wherein the noise parameter is junction capacitance.

[0170] 21. The method according to clause 18, wherein the second section surrounds at least 50% of the first section.

[0171] 22. The method according to clause 21, wherein the second section completely surrounds the first section.

[0172] 23. The method according to clause 18, wherein the first section has a shape that is substantially rectangular-based.

[0173] 24. The method according to clause 23, wherein the shape that is substantially rectangular-based is a shape that is substantially square-based.

[0174] 25. The method according to clause 18, wherein the dimension of the first section in the first direction is at least 1 mm.

[0175] 26. The method according to clause 18, wherein:

[0176] The shape of the first detector region corresponds to the shape of the FOV on the sample surface in the first scan.

[0177] 27. The method according to clause 18, wherein:

[0178] The shape of the second detector region corresponds to the shape of the FOV on the sample surface in the second scan.

[0179] 28. The method according to clause 18, further comprising:

[0180] Detecting charged particles at a third section that is at least adjacent to a first side of the second detector region;

[0181] Detecting charged particles at a fourth section that is at least adjacent to a second side of the second detector region, the second side being opposite to the first side; and

[0182] Determining an alignment parameter based on the charged particles detected at the third section and the fourth section.

[0183] 29. The method according to clause 18, wherein the charged particle detector includes an aperture located outside the boundary of the first section.

[0184] 30. The method according to clause 29, wherein the aperture is located in the second section.

[0185] 31. The method according to clause 18, wherein the first exposure setting or the second exposure setting includes one of a FOV size, a landing energy, a beam aperture setting, a beam current, a lens setting, a deflector setting, and an image compensation unit setting.

[0186] 32. The method according to clause 18, wherein:

[0187] The first exposure setting includes a first FOV size;

[0188] The second exposure setting includes a second FOV size; and

[0189] The second FOV size is greater than the first FOV size.

[0190] 33. The method according to clause 18, wherein:

[0191] The first exposure setting includes a first landing energy;

[0192] The second exposure setting includes a second landing energy; and

[0193] The second landing energy is higher than the first landing energy.

[0194] 34. The method according to clause 18, wherein:

[0195] The first exposure setting includes a first beam aperture setting;

[0196] The second exposure setting includes a second beam aperture setting; and

[0197] The second beam aperture setting is larger than the first beam aperture setting.

[0198] 35. The method according to clause 18, wherein:

[0199] The first exposure setting includes a first beam current;

[0200] The second exposure setting includes a second beam current; and

[0201] The second beam current is larger than the first beam current.

[0202] 36. The method according to clause 18, wherein:

[0203] The first detector region captures more than 90% of the emitted charged particles from the first scan.

[0204] 37. The method according to clause 18, wherein:

[0205] The second detector region captures more than 90% of the emitted charged particles from the second scan.

[0206] 38. A non - transitory computer - readable medium storing an instruction set that can be executed by at least one processor of a device to cause the device to perform a method, including:

[0207] Performing a first scan of a sample surface with a charged particle beam under a first exposure setting so that the emitted charged particles from the sample surface land in a first detector region of a charged particle detector, the first detector region including a first noise value of a noise parameter;

[0208] Generating a first image based on the first scan;

[0209] Perform a second scan of the sample surface with a charged particle beam under a second exposure setting such that emitted charged particles from the sample surface land in a second detector region of a charged particle detector, the second detector region including a second noise value of a noise parameter, the second noise value being higher than the first noise value; and

[0210] Generate a second image based on the second scan, the first image having a higher accuracy than the accuracy of the second image, wherein

[0211] The first detector region includes a first section of the charged particle detector,

[0212] The second detector region includes the first section and a second section of the charged particle detector, and

[0213] The second detector region is larger than the first detector region.

[0214] 39. A method for detecting charged particle events in a charged particle detector, comprising:

[0215] Select an exposure setting of a charged particle beam exposure device;

[0216] Select a first detector region or a second detector region of the charged particle detector based on the exposure setting;

[0217] Perform a charged particle beam exposure under the selected exposure setting; and

[0218] Generate an image based on charged particle detection at the selected first detector region or second detector region, wherein

[0219] The first detector region includes a first section of the charged particle detector and includes a first noise value of a noise parameter,

[0220] The second detector region includes the first section and a second section of the charged particle detector and includes a second noise value of a noise parameter, the second noise value being higher than the first noise value, and

[0221] The second detector region is larger than the first detector region.

[0222] 40. A non - transitory computer - readable medium storing a set of instructions that can be executed by at least one processor of a device to cause the device to perform a method, the method comprising:

[0223] Select an exposure setting of a charged particle beam exposure device;

[0224] Select a first detector region or a second detector region of the charged particle detector based on the exposure setting;

[0225] Perform a charged particle beam exposure under the selected exposure setting; and

[0226] Generate an image based on charged particle detection at a selected first detector region or second detector region, wherein

[0227] The first detector region includes a first section of the charged particle detector and includes a first noise value of a noise parameter,

[0228] The second detector region includes a first section and a second section of the charged particle detector and includes a second noise value of a noise parameter, the second noise value being higher than the first noise value, and

[0229] The second detector region is larger than the first detector region.

[0230] 41. A charged particle detector, comprising:

[0231] A top conductive layer including a detection surface;

[0232] A bottom conductive layer;

[0233] A semiconductor region between the top conductive layer and the bottom conductive layer, the semiconductor region including a first doped region of a first conductivity type adjacent to the top conductive layer, a second doped region of a second conductivity type adjacent to the bottom conductive layer, and an intrinsic region between the first doped region and the second doped region, the second conductivity type being different from the first conductivity type; and

[0234] An aperture configured to allow a primary charged particle beam to pass through, wherein

[0235] The detection surface extends to the edge of the aperture.

[0236] 42. The charged particle detector according to clause 41, wherein the detection surface extends to the entire perimeter of the aperture edge.

[0237] 43. The charged particle detector according to clause 41, wherein the sidewall adjacent to the aperture includes another detection surface.

[0238] 44. The charged particle detector according to clause 41, wherein:

[0239] The first doped region extends along the detection surface and along the sidewall of the aperture.

[0240] 45. The charged particle detector according to clause 44, wherein:

[0241] The first doped region extends to a non-sensitive surface including a non-conductive material.

[0242] 46. The charged particle detector according to clause 41, further comprising:

[0243] A non-sensitive surface including a non-conductive material, the non-sensitive surface surrounding the aperture and contacting one of the bottom conductive layer or the second doped region.

[0244] 47. The charged particle detector according to clause 46, wherein the non-sensitive surface includes silicon dioxide (SiO2).

[0245] 48. The charged particle detector according to clause 46, wherein the non-sensitive surface includes an outer diameter between 4 mm and 8 mm.

[0246] 49. The charged particle detector according to clause 41, wherein the aperture includes a diameter between 200 μm and 400 μm.

[0247] 50. The charged particle detector according to clause 41, wherein the top conductive layer includes aluminum (Al).

[0248] 51. The charged particle detector according to clause 41, wherein the bottom conductive layer includes one of titanium (Ti) or gold (Au).

[0249] 52. The charged particle detector according to clause 41, wherein the top conductive layer extends along the sidewall of the aperture.

[0250] 53. The charged particle detector according to clause 41, wherein the first doped region includes a p-type dopant.

[0251] 54. The charged particle detector according to clause 53, wherein the p-type dopant includes boron.

[0252] 55. The charged particle detector according to clause 41, wherein the second doped region includes an n-type dopant.

[0253] 56. The charged particle detector according to clause 55, wherein the n-type dopant includes one of arsenic, phosphorus, or antimony.

[0254] A non-transitory computer-readable medium consistent with embodiments of the present disclosure can be provided, which stores instructions for a processor of a controller (e.g., Figure 1 or Figure 2B controller 109 in Figure 2B or the image processing system 199 in Figures 8 - 9An exemplary flowchart detects charged particles. For example, instructions stored in a non-transitory computer-readable medium can be executed by circuitry of a controller to perform method 800 or method 900 in whole or in part. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid state drives, magnetic tape, or any other magnetic data storage medium, compact disc read-only memory (CD-ROM), any other optical data storage medium, any physical medium with a hole pattern, random access memory (RAM), programmable read-only memory (PROM), and erasable programmable read-only memory (EPROM), FLASH-EPROM, or any other flash memory, non-volatile random access memory (NVRAM), cache, registers, any other memory chip or cartridge memory, and networked versions thereof.

[0255] The block diagrams in the figures may illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer hardware or software products according to various exemplary embodiments of the present disclosure. In this regard, each block in the schematic diagram may represent some arithmetic or logical operation processing that can be implemented using hardware, such as electronic circuitry. A block may also represent a module, a section, or a portion of code that includes one or more executable instructions for implementing a specified logical function. It should be understood that in some alternative implementations, the functions indicated in the blocks may not occur in the order shown in the figures. For example, two blocks shown in succession may be executed or implemented substantially simultaneously, or sometimes the two blocks may be executed in the reverse order, depending on the functionality involved. Some blocks may also be omitted. It should also be understood that each block in the block diagrams, and combinations of blocks, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or by a combination of dedicated hardware and computer instructions.

[0256] It should be understood that the embodiments of the present disclosure are not limited to the exact configurations described above and illustrated in the figures, and various modifications and changes can be made without departing from its scope. For example, a charged particle inspection system can be just one example of a charged particle beam system consistent with the embodiments of the present disclosure.

Claims

1. A segmented multi-channel detector, comprising: A first detector region having a first segment; and a second detector region having the first segment and a second segment, the second segment surrounding at least 50% of the first segment, wherein the first detector region includes a first noise value of a noise parameter; and the second detector region includes a second noise value of the noise parameter, the second noise value being higher than the first noise value.

2. The segmented multi-channel detector according to claim 1, wherein the noise parameter is a capacitance.

3. The segmented multi-channel detector according to claim 1, wherein the noise parameter is a junction capacitance.

4. The segmented multi-channel detector according to claim 1, wherein the second section completely surrounds the first section.

5. The segmented multi-channel detector according to claim 1, wherein the first section has a rectangle-based shape.

6. The segmented multi-channel detector according to claim 4, wherein the rectangle-based shape is a square-based shape.

7. The segmented multi-channel detector according to claim 1, wherein the dimension of the first section in the first direction is at least 1 mm.

8. The segmented multi-channel detector according to claim 1, wherein: The shape of the first detector region corresponds to the shape of a first FOV on the sample surface in a charged particle beam apparatus.

9. The segmented multi-channel detector according to claim 8, wherein: The shape of the second detector region corresponds to the shape of a second FOV on the sample surface in the charged particle beam apparatus, the second FOV being larger than the first FOV.

10. The segmented multi-channel detector according to claim 1, further comprising: A third segment adjoining at least a first side of the second detector region; and a fourth segment adjoining at least a second side of the second detector region, the second side being opposite to the first side.

11. The segmented multi-channel detector according to claim 1, further comprising an aperture located outside the first section.

12. The segmented multi-channel detector according to claim 9, wherein the aperture is located in the second section.

13. A charged particle beam device, comprising: A charged particle beam source configured to generate a primary charged particle beam; A charged particle optical system configured to scan the primary charged particle beam over a field of view FOV on the sample surface; and The segmented multi-channel detector according to claim 1.

14. The charged particle beam device according to claim 13, wherein: The shape of the first detector region corresponds to the shape of the FOV on the sample surface.

15. The charged particle beam device according to claim 13, wherein: The shape of the second detector region corresponds to the shape of the FOV on the sample surface.

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