Charged particle beam detector with adaptive detection area for multiple field of view settings

Abstract

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

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application No. 63 / 421,870, filed November 2, 2022, and U.S. Patent Application No. 63 / 591,417, filed October 18, 2023, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION

[0002] The description herein relates to detectors that may be useful in the field of charged particle beam systems, and in particular to systems and methods that may be applied to charged particle detection using charged particle counting. [Background technology]

[0003]

[0003] Detectors can be used to sense physically observable phenomena. For example, a charged particle beam tool such as an electron microscope may include a detector that receives charged particles projected from a sample and outputs a detection signal. The detection signal can be used to reconstruct an image of the sample structure under inspection, and can be used, for example, to reveal defects in the sample. Detection of sample defects is becoming increasingly important in the manufacture of semiconductor devices, which may include a large number of densely packed and miniaturized integrated circuit (IC) components. Inspection systems can be provided for this purpose.

[0004]

[0004] Existing detection systems may have an undesirably high signal-to-noise ratio (SNR). Another consideration may be the charged particle beam collection rate. Summary of the Invention [Means for solving the problem]

[0005]

[0005] 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 may include a first detector region and a second detector region. The first detector region may have a first segment, and the second detector region may have a first segment and a second segment. The second segment may surround at least 50% of the first segment. The first detector region may include a first noise value of a noise parameter, and the second detector region may include a second noise value (higher than the first noise value) of the noise parameter.

[0006] Some embodiments of the present disclosure provide a charged particle beam device including the segmented multi-channel detector described above. The charged particle beam device may further include a charged particle beam source configured to generate a beam of primary charged particles, and charged particle optics configured to scan the beam of primary charged particles across a field of view (FOV) of a sample surface.

[0007] 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 under a first exposure setting to cause emitted charged particles from the sample surface to land in a first detector area of ​​the charged particle detector, the first detector area 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 under a second exposure setting to cause emitted charged particles from the sample surface to land in a second detector area of ​​the charged particle detector, the second detector area 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 higher accuracy than the second image. The first detector area may include a first segment of the charged particle detector, and the second detector area may include the first segment and a second segment of the charged particle detector. The second detector area may be larger than the first detector area.

[0008]

[0008] Some embodiments of the present disclosure provide a non-transitory computer-readable medium, which may store a set of instructions executable by at least one processor of a device to cause the device to perform the above-described method.

[0009] Some embodiments of the present disclosure provide a charged particle detector, which may include: an upper conductive layer including a detection surface; a lower conductive layer; a semiconductor region between the upper and lower conductive layers, the semiconductor region including a first doped region of a first conductivity type adjacent to the upper conductive layer, a second doped region of a second conductivity type adjacent to the lower conductive layer, the second conductivity type different from the first conductivity type, and an intrinsic region between the first and second doped regions; and an aperture configured to allow a primary charged particle beam to pass therethrough, the detection surface extending to an edge of the aperture.

[0010]

[0010] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the disclosed embodiments as may be claimed.

[0011]

[0011] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagrammatic representation of an exemplary electron beam inspection (EBI) system consistent with an embodiment of the present disclosure. [Figure 2A]

[0013] FIG. 1 illustrates a charged particle beam device, which may be an example of an electron beam tool, consistent with embodiments of the present disclosure. [Figure 2B]

[0013] FIG. 1 illustrates a charged particle beam device that may be an example of an electron beam tool consistent with an embodiment of the present disclosure. [Figure 2C]

[0013] FIG. 1 illustrates a charged particle beam device that may be an example of an electron beam tool consistent with an embodiment of the present disclosure. [Figure 3A]

[0014] 1 is a diagrammatic representation of the detector structure. [Figure 3B] 1 is a diagrammatic representation of the structure of a detector. [Figure 3C] 1 is a diagrammatic representation of the structure of a detector. [Figure 3D] 1 is a diagrammatic representation of the structure of a detector. [Figure 4]

[0015] 1 is a diagrammatic representation of a sample field of view (FOV) and corresponding detection plane according to an embodiment of the present disclosure. [Figure 5]

[0016] 1 is a diagrammatic representation illustrating various factors that may contribute to noise in an imaging channel of a charged particle detector according to an embodiment of the present invention. [Figure 6A]

[0017] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 6B] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 6C] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 6D] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 7A]

[0018] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 7B] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 7C] 1 is a diagrammatic representation of an exemplary segmented charged particle detector in accordance with an embodiment of the present invention. [Figure 8]

[0019] 1 is a flowchart illustrating an exemplary method for detecting charged particles according to some embodiments of the present disclosure. [Figure 9]

[0020] 1 is a flowchart illustrating an exemplary method for detecting charged particles according to an embodiment of the present disclosure. [Figure 10A]

[0021] 1 is a diagrammatic representation of a charged particle detector according to an embodiment of the present disclosure. [Figure 10B] 1 is a diagrammatic representation of a charged particle detector according to an embodiment of the present disclosure. [Figure 10C] 1 is a diagrammatic representation of a charged particle detector according to an embodiment of the present disclosure. [Figure 11A]

[0022] 1 is a diagrammatic representation of a charged particle detector according to an embodiment of the present invention. [Figure 11B] 1 is a diagrammatic representation of a charged particle detector according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0023] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the drawings. The following description refers to the accompanying drawings, in which like numbers in different drawings represent the same or similar elements unless otherwise stated. Implementations described in the following description of exemplary embodiments do not represent all implementations consistent with the present invention. Instead, these implementations are merely examples of apparatus, 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 utilizing charged particle beams (e.g., electron beams), the disclosure is not so limited. Other types of charged particle beams (e.g., photon beams) may be similarly applied. Furthermore, other imaging systems, such as optical imaging, light detection, x-ray detection, etc., may be used.

[0014]

[0024] Electronic devices are built with circuits formed on a piece of silicon called a substrate. Many circuits can be formed together on the same piece of silicon, called an integrated circuit, or IC. As technology advances, the size of these circuits has dramatically decreased, allowing more circuits to fit on a substrate. For example, an IC chip in a smartphone may be only about the size of a fingernail, yet it can contain over 2 billion transistors, each less than 1 / 1000 the width of a human hair.

[0015]

[0025] Creating these ICs with extremely small structures and components is a time-consuming, complex, and expensive process, often involving hundreds of individual steps. An error in even one step can result in a defect in the finished IC, rendering it useless. Therefore, one of the goals of the manufacturing process is to avoid such defects in order to maximize the number of functioning ICs created by the process, i.e., to increase the overall yield of the process.

[0016]

[0026] One factor in improving yield is monitoring the chip fabrication process to ensure that it produces a sufficient number of functional integrated circuits. One way to monitor the process is to inspect chip circuit structures at various stages of their formation. Inspection can be done by using a scanning charged-particle microscope (SCPM). For example, an SCPM can be a scanning electron microscope (SEM). An SEM can be used to image these extremely small structures, effectively taking a "picture" of the structure. The image can be used to determine whether the structure formed correctly and can also be used to determine whether the structure formed in the correct location. If the structure is defective, the process can be adjusted to make the defect less likely to recur. To increase throughput (e.g., number of samples processed per hour), it is desirable to perform inspection as quickly as possible.

[0017]

[0027] The operating principle of an SEM is similar to that of a raster scan camera. A raster camera captures a picture by receiving and recording, pixel by pixel, the intensity of light reflected or emitted from a person or object. An SEM captures a "picture" by receiving and recording the energy or quantity of electrons reflected or emitted from a structure or water. Before capturing such a "picture," an electron beam can be projected onto the structure, and as electrons reflect or emit (emit) from the structure (e.g., from the water surface, from structures below the water surface, or both), a detector in the SEM can receive and record the energy or quantity of those electrons to generate an inspection image. To capture such a "picture," the electron beam can scan the wafer (e.g., row by row or in a zigzag fashion), and the detector can receive the emitted electrons from one area (called a "beam spot") under the electron beam projection. The detector can receive and record the emitted electrons from each beam spot one at a time and combine the recorded information for all beam spots to generate an inspection image. Some SEMs use a single electron beam (called a "single-beam SEM") to take a single "picture" and generate an inspection image, while some SEMs use multiple electron beams (called a "multi-beam SEM") to take multiple "sub-pictures" of the wafer in parallel, and in some cases stitch them together to generate the inspection image. By using multiple electron beams, the SEM can provide more electron beams onto the structure to capture these multiple "sub-pictures," resulting in more electrons emerging from the structure. Thus, the detector can simultaneously receive more emerging electrons, thereby generating inspection images of the wafer's structures with greater efficiency and speed.

[0018]

[0028] Typically, the detection process involves measuring the magnitude of an electrical signal generated when an electron lands on a detector. The intensity of the secondary beam can be determined based on the electrical signal generated in the detector, which varies proportionally to changes in the intensity of the secondary beam.

[0019]

[0029] To obtain accurate intensity readings and produce accurate images, it is important to collect as many of the emitted electrons as possible. Because electrons tend to land on the detector surface in a scattered distribution (e.g., in clusters spreading from its center), one way to achieve a higher collection rate is to provide a large detection surface area. However, some unwanted electrical effects become more noticeable with increasing detection surface area. These unwanted effects can increase noise in the detection signal. For example, junction capacitance is an electrical parameter that can be directly related to the size of the detection surface. Therefore, it may be desirable to provide a detector with only enough surface area to capture enough electrons for a given exposure.

[0020]

[0030] However, electron beam tools (such as SEM tools) operate under various settings that may change the amount of surface area required. For example, an SEM tool may scan a large or small portion of the sample surface (known as the field of view (FOV)). As a larger FOV is scanned, a larger detector surface is required to collect enough electrons for precision measurements. Therefore, it may be desirable to provide a detector with multiple detector surface segments that can be tailored to match the expected electron distributions from various FOV sizes. Conventional segmented detectors may not be designed in a manner that efficiently and effectively captures these various distributions.

[0021]

[0031] Some embodiments of the present disclosure may provide a segmented charged particle detector. The detector may include a first segment designed to capture a majority of electrons emitted from a small FOV scan. The first segment may have a shape that matches the small FOV, such as a rectangular base shape. For example, the rectangular base shape may be approximately square, approximately rectangular, or may have a shape that matches the expected electron distribution from the small FOV (e.g., 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 therefore may produce a more accurate image.

[0022]

[0032] 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 a majority of electrons emitted from a large FOV scan. The first and second segments may have a shape (e.g., a rectangular base shape) that matches the large FOV. For example, the rectangular base shape may be approximately square, approximately rectangular, or a shape (e.g., a distorted square) that matches the expected electron distribution from the large FOV. The first and second segments may form a second detection area. The second detection area may have a higher noise value due to its larger size and therefore may produce a lower-precision image. However, the second detection area may capture a greater number of electrons than the first detection area.

[0023]

[0033] In this way, the detector may allow a tradeoff to be selected between noise and collection rate depending on the parameters of a particular charged particle beam exposure. In some embodiments, parameters other than FOV size may influence the selection of the detection area. 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.

[0024]

[0034] The objects and advantages of the present disclosure may be achieved by the elements and combinations as described in the embodiments discussed herein. However, not every embodiment of the present disclosure is required to achieve such exemplary objects or advantages, and thus some embodiments may not achieve any of the stated objects or advantages.

[0025]

[0035] Without limiting the scope of the present disclosure, some embodiments may be described in the context of providing detection systems and methods therein that utilize electron beams (“e-beams”). However, the disclosure is not so limited. Other types of charged particle beams (such as proton beams) may be applied as well. Furthermore, the systems and methods 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 infrared, visible light, UV, DUV, EUV, x-ray, or light within any other wavelength range. Thus, although detectors in the present disclosure may be disclosed with respect to electron detection, some embodiments of the present disclosure may be directed to the detection of other charged particles or photons.

[0026]

[0036] As used herein, unless specifically stated otherwise, the term "or" includes all possible combinations except where impracticable. For example, if it is stated that a component includes A or B, then the component may include A or B, or A and B, unless specifically stated otherwise or where impracticable. As a second example, if it is stated that a component may include A, B, or C, then the component may include A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C, unless specifically stated otherwise or where impracticable.

[0027]

[0037] Referring now to FIG. 1 , FIG. 1 illustrates an exemplary electron beam inspection (EBI) system 10 that can be used for wafer inspection consistent with embodiments of the present disclosure. As shown in FIG. 1 , 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 can be used for imaging. The EFEM 30 includes a first load port 30 a and a second load port 30 b. The EFEM 30 may include additional load ports. The first load port 30 a and the second load port 30 b receive wafer front-opening integrated pods (FOUPs) containing wafers (e.g., semiconductor wafers or wafers made of other materials) or samples to be inspected (wafers and samples may be collectively referred to herein as “wafers”).

[0028]

[0038] One or more robot arms (not shown) of the EFEM 30 can transfer wafers to the load / lock chamber 20. The load / lock chamber 20 is connected to a load / lock vacuum pumping system (not shown), which removes gas molecules from the load / lock chamber 20 to reach a first pressure below atmospheric pressure. After the first pressure is reached, one or more robot arms (not shown) can transfer the wafers from the load / lock chamber 20 to the main chamber 11. The main chamber 11 is connected to a main chamber vacuum pumping system (not shown), which removes gas molecules from the main chamber 11 to reach a second pressure below the first pressure. After the second pressure is reached, the wafers are inspected by the electron beam tool 100. The electron beam tool 100 can be a single-beam system or a multi-beam system. A controller 109 is electronically connected to the electron beam tool 100 and can be electronically connected to other components as well. The controller 109 may be a computer configured to perform various controls of the EBI system 10. In Figure 1, the controller 109 is shown as being external to the structure including the main chamber 11, the load / lock chamber 20, and the EFEM 30, but it is understood that the controller 109 may also be part of the structure.

[0029]

[0039] In some embodiments, the controller 109 may include one or more processors (not shown). A processor may be a general-purpose or special-purpose electronic device capable of manipulating or processing information. For example, a processor may include any combination of a central processing unit (i.e., "CPU"), a graphics processing unit (i.e., "GPU"), an optical processor, a programmable logic controller, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a programmable logic array (PLA), a programmable array logic (PAL), a general-purpose array logic (GAL), a complex programmable logic device (CPLD), a field programmable gate array (FPGA), a system-on-chip (SoC), an application-specific integrated circuit (ASIC), and any type of circuit capable of processing data. A processor may also be a virtual processor, including one or more processors distributed across multiple machines or devices coupled via a network.

[0030]

[0040] In some embodiments, controller 109 may further include one or more memories (not shown). Memory may be a general-purpose or special-purpose electronic device capable of storing code and data accessible by a processor (e.g., via a bus). For example, memory may include random-access memory (RAM), read-only memory (ROM), optical disk, magnetic disk, hard drive, solid-state drive, flash drive, security digital (SD) card, memory stick, compact flash (CF) card, or any type of storage device. The code and data may include an operating system (OS) and one or more application programs (i.e., "apps") for specific tasks. Memory may also be virtual memory, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0031]

[0041] Charged particle beam microscopes, such as those formed by or included in EBI system 10, may be capable of resolution down to the nanometer scale, for example, and may serve as practical tools for inspecting IC components on wafers. Using an e-beam system, electrons from a primary electron beam can be focused at a probe spot on the wafer under inspection. The interaction of the primary electrons with the wafer can form a secondary particle beam. The secondary particle beam can include backscattered electrons, secondary electrons, Auger electrons, or the like, resulting from the interaction of the primary electrons with the wafer. The characteristics (e.g., intensity) of the secondary particle beam can vary based on the internal or external structure or material properties of the wafer, thereby indicating whether the wafer contains defects.

[0032]

[0042] The intensity of the secondary particle beam can be determined using a detector. The secondary particle beam can form a beam spot on the detector surface. The detector can generate an electrical signal (e.g., current, charge, voltage, etc.) representing the intensity of the detected secondary particle beam. The electrical signal can be measured by a measurement circuit, which may include additional components (e.g., an analog-to-digital converter) to obtain the distribution of detected electrons. The electron distribution data collected during the detection time window can be combined with corresponding scan path data of the primary electron beam incident on the wafer surface 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 to reveal defects that may be present in the wafer. There are two ways for CD-SEM to perform image reconstruction based on signals: based on signal amplitude integration within each scan pixel; or based on signal pulse edge detection and identification. At each scan pixel location, multiple electrical signal pulses collected by different detector segments can have different pulse waveforms. These different pulse waveforms contain information about the electron energy distribution collected by the detector. Electrons with higher energy can cause a faster rise time of the electrical pulse waveform. With multiple segments (four channels) of the detector, up to four pulse edge detection image channels can be used to perform electron energy analysis, resulting in higher SEM resolution.

[0033]

[0043] 2A illustrates a charged particle beam device that may be an example of an electron beam tool 100 consistent with embodiments of the present disclosure. FIG. 2A illustrates a device that uses multiple beamlets formed from a primary electron beam to simultaneously scan multiple locations on a wafer.

[0034]

[0044] As shown in FIG. 2A , the electron beam tool 100A may 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 optics 220, a wafer stage (not shown in FIG. 2A ), multiple secondary electron beams 236, 238, and 240, a secondary optics 242, and an electron detection device 244. The electron source 202 may generate primary particles, such as electrons, in the primary electron beam 210. A controller, an image processing system, and the like may be coupled to the electron detection device 244. The primary projection optics 220 may include a beam separator 222, a deflection scanning unit 226, and an objective lens 228. The electron detection device 244 may include detection subregions 246, 248, and 250.

[0035]

[0045] Electron source 202, gun aperture 204, condenser lens 206, source conversion unit 212, beam separator 222, deflection scanning unit 226, and objective lens 228 can be aligned with a primary optical axis 260 of apparatus 100A. Secondary optics 242 and electron detection device 244 can be aligned with a secondary optical axis 252 of apparatus 100A.

[0036]

[0046] The electron source 202 may include a cathode, extractor, or anode, and primary electrons may be emitted from the cathode and then extracted or accelerated to form a primary electron beam 210 with a crossover (virtual or real) 208. The primary electron beam 210 may be visualized as being emitted from the crossover 208. The gun aperture 204 may block electrons at the periphery of the primary electron beam 210 to reduce the size of the probe spots 270, 272, 274.

[0037]

[0047] The source conversion unit 212 may include an image-forming element array (not shown in FIG. 2A ) and a beam-limiting aperture array (not shown in FIG. 2A ). Examples of the source conversion unit 212 can be found in U.S. Pat. No. 9,691,586, U.S. Patent Application Publication No. 2017 / 0025243, and International Patent Application No. PCT / EP2017 / 084429, all of which are incorporated herein by reference in their entirety. The image-forming element array may include a micro-deflector or a micro-lens array. The image-forming element array may form multiple parallel images (virtual or real) of the crossover 208 using multiple beamlets 214, 216, and 218 of the primary electron beam 210. The beam-limiting aperture array may limit the multiple beamlets 214, 216, and 218.

[0038]

[0048] The condenser lens 206 can focus the primary electron beam 210. The currents of the beamlets 214, 216, and 218 downstream of the source conversion unit 212 can be varied by adjusting the focusing power of the condenser lens 206 or by changing the radial size of the corresponding beam-limiting apertures in the beam-limiting aperture array. The condenser lens 206 can be an adjustable condenser lens that can be configured to move the position of its first principal plane. The adjustable condenser lens can be configured to be magnetic, so that the off-axis beamlets 216 and 218 land on the beamlet-limiting apertures at a rotation angle. The rotation angle varies with the focusing power and the position of the first principal plane of the adjustable condenser lens. In some embodiments, the adjustable condenser lens can be an adjustable anti-rotation condenser lens that includes an anti-rotation lens with a movable first principal plane. Examples of adjustable focusing lenses are further described in U.S. Patent Application Publication No. 2017 / 0025241, which is incorporated by reference herein in its entirety.

[0039]

[0049] The objective lens 228 can focus the beamlets 214, 216, 218 onto the wafer 230 for inspection and can form multiple probe spots 270, 272, 274 on the surface of the wafer 230. Secondary electron beamlets 236, 238, 240 can be formed to emit from the wafer 230 and return towards the beam separator 222.

[0040]

[0050] The beam separator 222 may be a Wien filter-type beam separator that generates an electrostatic dipole field and a magnetic dipole field. In some embodiments, when these fields are applied, the force exerted on the electrons of the beamlets 214, 216, and 218 by the electrostatic dipole field may be equal in magnitude and opposite in direction to the force exerted on the electrons by the magnetic dipole field. Thus, the beamlets 214, 216, and 218 may pass straight through the beam separator 222 with zero deflection angle. However, the total dispersion of the beamlets 214, 216, and 218 generated by the beam separator 222 may be non-zero. The beam separator 222 may separate the secondary electron beams 236, 238, and 240 from the beamlets 214, 216, and 218 and direct the secondary electron beams 236, 238, and 240 toward the secondary optics 242.

[0041]

[0051] The deflection scanning unit 226 can deflect the beamlets 214, 216, 218 to scan the probe spots 270, 272, 274 across the surface area of ​​the wafer 230. In response to the beamlets 214, 216, 218 impinging on the probe spots 270, 272, 274, secondary electron beams 236, 238, 240 can be emitted from the wafer 230. The secondary electron beams 236, 238, 240 can include electrons with a distribution of energies, including secondary electrons and backscattered electrons. The secondary optics 242 can focus the secondary electron beams 236, 238, 240 onto detection subregions 246, 248, 250 of the electron detection device 244. The detection subregions 246, 248, 250 can be configured to detect the corresponding secondary electron beams 236, 238, 240 and generate corresponding signals used to reconstruct an image of the surface of the wafer 230.

[0042]

[0052] The generated signals may represent the intensities of the secondary electron beams 236, 238, and 240 and may be provided to an image processing system (such as image processing system 199 provided in FIG. 2B below) in communication with the detection device 244, the primary projection optics 220, and the motorized wafer stage. The speed of movement of the motorized wafer stage may be synchronized and coordinated with the beam deflection controlled by the deflection scanning unit 226 so that the movement of the scanning probe spots (e.g., scanning probe spots 270, 272, and 274) can adequately cover the region of interest on the wafer 230. Such synchronization and coordination parameters may be adjusted to accommodate different materials of the wafer 230. For example, different materials of the wafer 230 may have different resistance-capacitance characteristics that may cause different signal sensitivities to the movement of the scanning probe spots.

[0043]

[0053] The intensities of secondary electron beams 236, 238, and 240 may vary according to the outer or inner structure of wafer 230, and thereby may indicate whether wafer 230 contains defects. Furthermore, as discussed above, beamlets 214, 216, and 218 may be projected at different locations on the upper surface of wafer 230 or to different sides of local structures on wafer 230 to generate secondary electron beams 236, 238, and 240 that may have different intensities. Thus, by mapping the intensities of secondary electron beams 236, 238, and 240 by area of ​​wafer 230, an image processing system may reconstruct an image reflecting features of the inner or outer structure of wafer 230.

[0044]

[0054] The detection sub-regions 246, 248, 250 may comprise separate detector packages, separate sensing elements, or separate regions of an array detector. In some embodiments, each detection sub-region may comprise a single sensing element.

[0045]

[0055] 2A shows detector 244 having several detection sub-regions aligned with secondary optical axis 252, it is understood that other multi-beam detector schemes may exist. For example, it is understood that a detector may correspond to each beamlet (such as a different detector for each of beamlets 214, 216, and 218). It is understood that these various detectors may be positioned below a main column corresponding to main axis 260. For example, these various detectors may be positioned between main projection optics 220 and the wafer stage.

[0046]

[0056] Another example of a charged particle beam device will now be discussed with reference to Figure 2B. Electron beam tool 100B (also referred to herein as device 100B) may be an example of electron beam tool 100 and may be similar to electron beam tool 100A shown in Figure 2A. However, unlike device 100A, device 100B may be a single-beam tool that uses only one primary electron beam to scan locations on a wafer one at a time.

[0047]

[0057] 2B, apparatus 100B includes a wafer holder 136 supported by a motorized stage 134 for holding a wafer 150 to be inspected. Electron beam tool 100B includes an electron emitter, which may include a cathode 103, an anode 121, and a gun aperture 122. 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. Objective lens assembly 132 may be a modified SORIL lens in some embodiments and includes a pole piece 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. In the detection or imaging process, an electron beam 161 emanating from the tip of the cathode 103 is accelerated by the voltage on the anode 121, passes through the gun aperture 122, the beam limiting aperture 125, the condenser lens 126, and is focused by a modified SORIL lens to a probe spot 170, which can impinge on the surface of the wafer 150. The probe spot 170 can be scanned across the surface of the wafer 150 by a deflector, such as deflector 132c or other deflectors of a SORIL lens. Secondary or scattered particles (such as secondary electrons or scattered primary electrons emanating from the wafer surface) are collected by a detector 144 to determine the intensity of the beam, so that an image of the area of ​​interest on the wafer 150 can be reconstructed.

[0048]

[0058] An image processing system 199 may also be provided, including the image acquirer 120, the storage 130, and the 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, and the like, 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 electrical conductors, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, a wireless radio, or a combination thereof. The image acquirer 120 may receive signals from the detector 144 and 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, contouring, overlaying indicators on the acquired image, and the like. The image acquirer 120 may be configured to perform adjustments, such as brightness and contrast, of the acquired image. The storage 130 may be a storage medium such as a hard disk, random access memory (RAM), cloud storage, other types of computer-readable memory, and the like. The storage 130 may be coupled to the image acquirer 120 and used to store raw scanned image data as original images or to store post-processed images. The image acquirer 120 and the storage 130 may be connected to the controller 109. In some embodiments, the image acquirer 120, the storage 130, and the controller 109 may be integrated together as a single electronic control unit.

[0049]

[0059] In some embodiments, the image acquirer 120 can acquire one or more images of the sample based on an imaging signal received from the detector 144. The imaging signal can correspond to a scanning motion to perform charged particle imaging. The acquired image can be a single image including multiple imaging areas that can include various features of the wafer 150. The single image can be stored in the storage 130. The imaging can be performed based on imaging frames.

[0050]

[0060] The collection and illumination optics of an electron beam tool can include or be supplemented by electromagnetic quadrupole electron lenses. For example, as shown in FIG. 2B , electron beam tool 100B can include a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lenses can be used to control the electron beam. For example, first quadrupole lens 148 can be controlled to adjust the beam current, and second quadrupole lens 158 can be controlled to adjust the beam spot size and beam shape.

[0051]

[0061] FIG. 2B illustrates a charged particle beam device that can use a single primary beam configured to generate secondary electrons by interacting with a wafer 150. As in the embodiment illustrated in FIG. 2B, the detector 144 can be positioned 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 in its center to allow the primary electron beam to pass through and reach the wafer 150. FIG. 2B illustrates an example of a detector 144 with an opening in its center. However, some embodiments can use a detector positioned off-axis with respect to the optical axis along which the primary electron beam travels. For example, as in the embodiment illustrated in FIG. 2A discussed above, a beam separator 222 can be provided to direct the secondary electron beam toward the off-axis detector. The beam separator 222 can be configured to redirect the secondary electron beam by an angle α toward the electron detection device 244, as shown in FIG. 2A.

[0052]

[0062] In some embodiments of the present disclosure, a PIN detector can be used as an in-lens detector in a retarding objective SEM column of the EBI system 10. The PIN detector can be placed between a cathode for generating an electron beam and the objective lens. The electron beam emitted from the cathode can be set to a potential of −BE keV (typically about −10 kV). Electrons in the electron beam can be immediately accelerated and passed through the column, which can be at ground potential. Thus, the electrons can travel with a kinetic energy of BE keV while passing through the aperture 145 of the detector 144. Electrons passing through the pole piece of the objective lens (such as pole piece 132a of the objective lens assembly 132 in FIG. 2B) can be rapidly decelerated to a landing energy of LE keV because the wafer surface potential can be set to −(BE-LE) keV.

[0053]

[0063] FIG. 2C illustrates an example of a charged particle beam device 100C according to an embodiment of the present disclosure. The charged particle beam device 100C may be, for example, the charged particle beam device 100A of FIG. 2A or the charged particle beam device 100B of FIG. 2B. Emitted electrons 171 (including, for example, secondary electrons or backscattered electrons) are emitted from the wafer surface due to impact with electrons of the primary electron beam 105. A retarding field that may retard the primary electrons as they approach the probe spot 170 may act as an accelerating field to accelerate the emitted electrons backward toward the detector 144 surface. For example, as shown in FIG. 2C, an interaction with the wafer 150 at the probe location 170 may generate emitted electrons 171 that return toward the detector 144.

[0054]

[0064] Emitted electrons 171 from the wafer surface traveling along the optical axis 105 may arrive at the surface of the detector 144 with a distribution of positions. As discussed above, the emitted electrons may include, for example, secondary electrons or backscattered electrons. In some embodiments, for example, the distribution may include 60-85% secondary electrons and 40-15% backscattered electrons. The landing point distribution may vary depending on the emission position and the SEM deflection field (e.g., scan range). Therefore, in some applications, if a large FOV of the SEM image is required, the required size of the in-lens PIN detector may be significantly larger. Typically, the detector may be, for example, 10 mm or larger in diameter. In some embodiments, the detector may be, for example, about 4-10 mm in diameter.

[0055]

[0065] The detector 144 may be positioned along the optical axis 105. The primary electron beam may be configured to travel along the optical axis 105. Thus, the detector 144 may include a hole 145 in its center to allow the primary electron beam to pass through and reach the wafer 150. FIGS. 2B-C show an example of a detector 144 having an aperture in its center. However, some embodiments may use a detector that is positioned off-axis with respect to the optical axis along which the primary electron beam travels. For example, as in the example shown in FIG. 2A, a beam separator 222 may be provided to direct the emitted electron beam toward the off-axis detector. The beam separator 222 may be configured to redirect the emitted electron beam by an angle α toward the electron detection device 244, as shown in FIG. 2A. Thus, in some embodiments of the present disclosure, a detector without any central aperture may be provided.

[0056]

[0066] Detector 244 of FIG. 2A or detector 144 of FIGS. 2B-C may include a sensing element, such as a diode or diode-like element, that can convert incident energy into a measurable signal. For example, the sensing element in the detector may include a SPAD, APD, or PIN diode. Although the sensing element may be represented as a diode throughout this disclosure, the sensing element or other components may deviate from the ideal circuit behavior of an electrical element, such as a diode, resistor, capacitor, etc. In some embodiments of the present disclosure, the detector in the charged particle beam system may include a pixelated array of multiple sensing elements.

[0057]

[0067] 3A-D show schematic diagrams of detectors 344a-d. Detectors 344a-d may include, for example, electron detectors, other charged particle detectors, or photon detectors. Detectors 344a-d may include apertures 345 configured to allow the primary electron beam to pass through the detector and impinge on the sample surface. Alternatively, detectors 344a-d may be configured to be positioned away from the primary beam axis and thus may not include apertures 345. Detectors 345a-d may include diodes such as PIN diodes, scintillators, radiation detectors, and solid-state detectors, among other charged particle sensing devices.

[0058]

[0068] In some embodiments, detectors 344a-d may include monolithic detectors (e.g., detector 344a) or segmented detectors (e.g., detectors 344b-d). In a monolithic detector, electron detection surface 346 may include a continuous layer of charged particle sensitive material that forms a single segment 350a corresponding to a single imaging channel, as shown in FIG. 3A. Detector 344a may be positioned within a charged particle beam device (e.g., a single beam device) such that the central axis of aperture 345 may be aligned with the beam axis of the primary electron beam.

[0059]

[0069] In some embodiments, a segmented detector may include two or more segments. In a segmented detector such as that shown in FIG. 3B, the electron detection surface 346 may include discontinuous layers of charged particle-sensitive material separated by non-sensitive material 302, such as the substrate material of detector 344b. Thus, the discontinuous layer may be divided into segments 350b and 351b. Each segment 350b and 351b may form a separate imaging channel and may be coupled to a separate detection output (not shown). Each of the segmented detectors 344b-d shown in FIGS. 3B-D may be cylindrical with a circular, elliptical, or polygonal cross-section. One or more segments of a segmented detector may be arranged in an asymmetric, radial, circumferential, or orientation-dependent manner around the beam axis of the primary electron beam. The charged particle-sensitive material may be sensitive to charged particles such as electrons. Alternatively, detectors 344a-d may be configured to detect charged particles other than electrons (e.g., protons). Additionally, detectors 344a-d may be configured to detect photons (such as IR, visible light, UV, DUV, EUV, X-rays, or light within any other wavelength range) instead of charged particles.

[0060]

[0070] In some embodiments, a segmented detector may include more than two segments. For example, segmented detector 344c of FIG. 3C may include four segments 350c, 351c, 352c, and 353c arranged circumferentially around central aperture 345. The four segments may be separated by non-sensitive material 302 (such as the substrate on which detector 344c is fabricated). Each segment 350c, 351c, 352c, and 353c may form a separate imaging channel and be coupled to a separate detection output. Thus, segmented detector 344c may represent a four-channel detector.

[0061]

[0071] In some embodiments, a segmented detector may include two or more segments, for example, arranged concentrically. For example, segmented detector 344d in FIG. 3D may include two segments 350d and 351d arranged around central aperture 345. Segmented detector 344d may represent a two-channel detector having a different geometry than two-channel detector 344b. The two segments may be separated by non-sensitive material 302 (such as the substrate on which detector 344d is fabricated). Each segment 350d and 351d may form a separate imaging channel and be coupled to a separate detection output. Alternatively, detector 344d may include three or more concentric imaging channels. For example, detector 344d may include three, four, five, or more concentric imaging channels.

[0062]

[0072] Further information regarding monolithic and segmented detectors can be found in U.S. Patent Application Publication No. 2021 / 0319977, which is incorporated by reference in its entirety.

[0063]

[0073] Figure 4 shows an example relationship between the probe spot of a primary beam scan within the field of view (FOV) of a sample and the corresponding distribution of electron landing positions on area 447 of detector 444. As indicated by the horizontal arrows within the FOV in Figure 4, the primary beam can be deflected to scan the probe spot along, for example, a series of parallel scan lines. While the field of view (FOV) shows a traditional raster scan profile, it will be understood that other scan profiles can be used, such as a traditional scan, a modified snake scan, or a modified raster scan profile, among others.

[0064]

[0074] Each discrete location along which the probe spot is scanned may generate emitted electrons, such as secondary or backscattered electrons, that may strike the detector 444 as a cluster of electron landing locations. In some embodiments, each individual cluster of electron landing locations may represent, for example, one pixel in the resulting image. Thus, the corresponding spot on the sample surface may be referred to as a sample pixel.

[0065]

[0075] In FIG. 4 , five such sample pixels 1-5 are depicted within the FOV along with their corresponding electron landing location clusters within region 447 of detector 444. The number and size of the depicted sample pixels are given for illustrative purposes only. For example, the FOV may be substantially covered by such sample pixels, and the detector surface near region 447 may be substantially covered by overlapping electron landing location clusters. If the probe spot illuminates the upper left corner at location 1 within the FOV, the cluster of electron landing locations may be centered at the corresponding corner of location 1 in region 447. The same applies to locations 2, 4, and 5. If the probe spot illuminates a central location at location 3 within the FOV, the cluster of electron landing locations may be centered at location 3 in region 447. In this way, for example, scanning a square-shaped FOV over the sample surface may produce an approximately square-shaped distribution of electron landing locations on the detector. It should be understood that the actual spatial relationships may vary from the schematic depiction shown. For example, the clusters of electron landing locations traced on region 447 may be streaked, eg, inverted, from their corresponding probe spots in the FOV.

[0066]

[0076] The landing locations of the emitted electrons may be substantially clustered within an area having a radius of, for example, 1 millimeter, 2-3 millimeters, or more. In addition to the central location varying with the deflection angle of the primary beam, other parameters may affect the distribution of electron landing locations. For example, the geometric spread of the landing locations of the emitted electrons may vary as a result of the electrons having different trajectories, for example, due to the electrons' initial kinetic energy and emission angle. Additionally, the central location and geometric spread of the cluster of electron landing locations on the detector surface may vary based on the condition of the charged particle beam device (e.g., of the charged particle beam device 100A, 100B, or 100C shown in Figures 2A-C). For example, a higher landing energy may result in a greater divergence of the emitted electrons, resulting in a greater geometric spread on the surface of the detector 444.

[0067]

[0077] As can be seen in Figure 4, the size, shape, and location 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 as well as the state of the charged particle beam device. Thus, for a given FOV exposure, not all of the detector surface is required. In conventional detectors (such as detectors 344a-d in Figures 3A-D), the size of the detection surface utilized can remain fixed even when charged particle beam process parameters (FOV size, landing energy, aperture size, beam current, lens / deflector settings, image compensation unit (ICU), etc.) are changed.

[0068]

[0078] Using such a large detection surface may allow for high electron collection and easier alignment, but may also result in reduced detection sensitivity and higher noise. For example, detector noise may be increased by parasitic capacitance within the detection system. Figure 5 shows an example circuit diagram illustrating various factors that may contribute to noise within a single imaging channel of a charged particle detector. For example, in a monolithic detector, the circuit diagram may represent the noise of the entire detector. In a two-channel detector, such as detector 344b in Figure 3B, the circuit diagram may represent the noise from one semicircular imaging channel 350b or 351b. Noise i EQ can be expressed as:

number

number

number

number

[0069]

[0079] The size of the detector surface is the total junction capacitance C D However, as discussed above, some detectors may have a fixed detection area even when the detector's active area (e.g., the area on which the emitted electrons impinge) is changed. For example, the detector's active area may change due to changes in FOV size, beam aperture setting, landing energy, lens / deflector setting, ICU tilt angle setting, or other parameters. Thus, such detectors may have a higher noise penalty that cannot be reduced, for example, when detecting small areas or even when using low landing energies. Furthermore, even if the detection area can be changed, for example, by excluding at least one imaging channel of a multi-channel segmented detector, the detector segments may not have a size, shape, or position that corresponds to the size, shape, or position of the FOV. Therefore, it may be difficult to change the effective detection area while maintaining high electron collection efficiency.

[0070]

[0080] 6A-D show examples of a segmented charged particle detector 644 according to some embodiments of the present invention. The charged particle detector 644 may be an electron detector configured for use in, for example, an SEM or other electron beam device (such as an device according to FIGS. 1, 2A, 2B, or 2C). The charged particle detector 644 may include a first segment 650, a second segment 651, a third segment 652, and a fourth segment 653. The first segment 650 may be coupled to a first detector output 650.1, the second segment 651 may be coupled to a second detector output 651.1, the third segment 652 may be coupled to a third detector output 652.1, and the fourth segment 653 may be coupled to a fourth detector output 653.1. The charged particle detector 644 may include an aperture 645 configured to allow an electron beam (e.g., a primary electron beam or beamlet) to pass through the detector and impinge on a sample surface. Alternatively, the charged particle detector 644 may be configured to be located away from the primary beam axis and therefore may not include an aperture 645 .

[0071]

[0081] 6A, the first segment 650 can be offset from the center of the detector 644 such that the aperture 645 is located 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, among other charged particle sensing devices. The segments 650-653 of the charged particle detector 644 can be separated by a non-sensitive material 602.

[0072]

[0082] The first detector region of the detector 644 may include a first segment 650. The second detector region may include not only the first segment 650 but also a second segment 651, which 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 FIG. 6A or 6B. Alternatively, the second segment 651 may border the first segment 650 (e.g., on two sides), as seen in FIG. 6C. The second segment 651 may surround, for example, 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 the detector 644 such that a portion of the first segment 650 substantially forms the outer boundary of the entire detector surface. In this case, the second segment 651 may border the first segment 650 on only two or three sides, and thus may surround only about 50% or 75% of the boundary of the first segment 650. As another example, the first segment 650 may border the second segment 651 on a portion of its boundary, and may then border another segment (such as the third segment 652 or the fourth segment 653) on the remainder of its boundary, as seen, for example, in FIG. 6D . In general, the second segment 651 may be positioned to form a second detector area in combination with the first segment 650.

[0073]

[0083] The segments of detector 644 can be shaped to produce detector regions corresponding to the typical shape of the FOV being scanned. For example, for a device capable of scanning a rectangular or square-shaped FOV (for example), the first detector region or second detector can have a rectangular base shape corresponding to the FOV shape. For example, the rectangular base shape can be approximately square, approximately rectangular, or a shape that matches the expected electron distribution from an approximately square or approximately rectangular FOV. The first detector region or second detector can have a shape with three flat sides and one curved side, as seen in the second detector region formed by the boundary of second segment 651 in FIG. 6A. Alternatively, the first detector region or second detector can have all flat sides, as seen in FIG. 6B. In some embodiments of the present disclosure, the sides of the first segment can be, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or more. In some embodiments of the present disclosure, the outside 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 more. Other FOV shapes are possible. Accordingly, in some embodiments of the present disclosure, other shapes of the first and second detector regions are similarly contemplated. In some embodiments, the shape of the segment or detector region may be designed to match the shape of the charged particle landing distribution associated with the FOV rather than matching the shape of the FOV itself. As an example, if a square FOV is expected to produce a distorted, square-like distribution on the detector surface (such as due to pincushion or barrel distortion), the segment or detector region may be shaped according to the pincushion or barrel distortion shape.

[0074]

[0084] The first detector region may have lower noise than the second detector region. For example, the first detector region may have a smaller surface area than the second detector region because the first detector region may include only the first segment 650. This smaller surface area results in lower noise (the lower noise value i discussed above in Equation 1 and FIG. 5). EQ The smaller junction capacitance C of the first detector region can lead to DThe second region may have a higher noise figure than the first region because the second region adds another junction capacitance from the second segment 651. However, the additional size of the second region may allow for greater electron collection.

[0075]

[0085] Thus, the detector 644 may allow a tradeoff to be selected between noise and collection rate depending on the parameters of a particular charged particle beam exposure. A charged particle beam device (such as any of devices 100, 100A, 100B, or 100C of FIGS. 1-2C) may scan a FOV over a sample surface and generate an image based on signals from, for example, one of the first and second detector regions. An image generated based on signals from the first detector region may have lower image channel noise, leading to higher image accuracy. For example, signals from the first detector region may have a lower electron root mean square (RMS) value than signals from the second detector region. Alternatively, an image generated based on signals from the second detector region may be desirable in view of a higher available collection surface.

[0076]

[0086] For example, a first charged particle beam exposure (such as an electron beam exposure in any of apparatuses 100, 100A, 100B, or 100C of FIGS. 1-2C) may include first exposure parameters that result in a first portion of charged particle landing locations falling within a first detector area on the first segment 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 another parameter that may affect the distribution of charged particle landing locations on the surface of the detector 644. The first portion may include, for example, 90% or more of the charged particle landing locations on the detector. In some embodiments, the majority may include, for example, 95%, 99%, 99.5%, 99.9%, or 99.99% of the charged particle landing locations on the detector. The first charged particle beam exposure may include a first noise value in a first detector area.

[0077]

[0087] The second charged particle beam exposure may include second exposure parameters that result in a second portion of charged particle landing locations falling within a second detector area on the first segment 650 and the second segment 651. The first and second exposure parameters may include, for example, different values ​​of the same parameter. For example, the first exposure parameters may include a first FOV size, and the second parameters may include a second FOV that is larger than the first FOV. The second charged particle beam exposure may include a second noise value within the second detector area. The second noise value may be higher than the first noise value.

[0078]

[0088] In some embodiments, the first charged particle beam exposure and the second charged particle beam exposure may not occur simultaneously. In some embodiments, the first and second portions of charged particle landing locations may be, for example, approximately equal. For example, the first charged particle beam exposure may include a first FOV size on the sample surface. The first FOV size may be, for example, a first portion in which >95% of the charged particle landing locations fall within a first detector area on the first segment 650. The second charged particle beam exposure may include a second FOV size on the sample surface that is larger than the first FOV size. The second FOV size may be, for example, a second portion in which >95% of the charged particle landing locations fall within a second detector area on the first segment 650 and the second segment 651. Alternatively, the second portion may be larger than the first portion.

[0079]

[0089] In some embodiments, the first charged particle beam exposure and the second charged particle beam exposure may occur simultaneously. In some embodiments, the first and second portions of charged particle landing locations may be different. For example, the charged particle beam exposure may include a first portion, e.g., where >95% of the charged particle landing locations fall within a first detector area on the first segment 650, and a second portion, e.g., where >95% of the charged particle landing locations fall within a second detector area on the first segment 650 and the second segment 651. The charged particle beam exposure may include a first noise level within the first detector area and a second noise level within the second detector area. In some embodiments, the operator may utilize a first detection signal from the first detector area, e.g., in terms of a lower noise value within the first detector area. In some embodiments, the operator may utilize a second detection signal from the second detector area, e.g., in terms of a higher collection rate within the second detector area. The second signal may include not only the first detected signal from the first segment 650 but also another detected signal from the second segment 651. In some embodiments, the second detected signal may include a weighted average or other mathematical combination of the first detected signal and the another detected signal.

[0080]

[0090] A first detected signal from a first detector area can be used to generate a first image of the sample with a first accuracy, and a second detected signal from a second detector area can be used to generate a second image of the sample with a second accuracy, which may be higher than the second accuracy.

[0081]

[0091] Charged particle detector 644 may include additional detector regions. For example, the charged particle detector may include a third detector region corresponding to third segment 652 and a fourth detector region corresponding to fourth segment 653. In some embodiments, signals from the third and fourth detector regions may be used, for example, to monitor beam alignment. In some embodiments, the charged particle detector may include a fifth detector region that includes all four segments. For example, the fifth detector region may be used for optimal collection of charged particle landing positions on the detector surface.

[0082]

[0092] 6A-D show four segments 650-653, some embodiments of the present disclosure are not limited in this respect. For example, a detector surface may include three or more nested detector segments, resulting in more selectable detector regions. For example, there may be smaller segments located within the first segment 650, or there may be larger detector segments surrounding the second segment 651 (e.g., located between the second segment 651 and the third and fourth segments 652-653).

[0083]

[0093] 7A-C show an example distribution of charged particle landing locations on a detector 744 according to some embodiments of the present invention. Detector 744 may be, for example, detector 644 of FIGS. 6A-D. As seen in FIG. 7A (corresponding labels omitted in FIGS. 7B-C), detector 744 may include, for example, four segments 750-753 similar to detector 644 of FIGS. 6A-D.

[0084]

[0094] FIG. 7A shows a first distribution of charged particle landing locations. The first distribution may correspond to a first charged particle beam exposure including, for example, a first value of an exposure parameter. The exposure parameters may include, for example, FOV size, beam aperture setting, landing energy, lens / deflector setting, ICU tilt angle setting, or another parameter. Similarly, FIGS. 7B and 7C may show second and third distributions of charged particle landing locations corresponding to second and third charged particle beam exposures including, for example, second and third values ​​of the exposure parameter. For example, the distributions in FIGS. 7A-C may correspond to three distributions of charged particle landing locations at low, medium, and high landing energy settings, respectively. As seen in FIG. 7A, a first detector area including segment 750 may capture a larger portion of charged particle landing locations at a low landing energy setting. Therefore, a first detector area with lower noise may be ideal for use with the first exposure. In FIG. 7B, the first detector area may not capture a sufficient amount of charged particle landing locations at a medium landing energy setting. However, the second detector area, including the first segment 750 and the second segment 751, may capture a sufficient amount at a higher noise penalty. Therefore, one of the first and second detector areas may be ideal for use with the second exposure. For example, the first detector area may be suitable for lower noise, or the second detector area may be suitable for a higher collection rate. In FIG. 7C, at a higher landing energy setting, there may be a significant distribution of electrons outside the second detector area. In this case, the second detector area may strike the right balance between noise and collection rate. Alternatively, a larger detector area, such as the fifth detector area discussed above, which includes all four segments of detector 744, may be employed.

[0085]

[0095] 8 is a flowchart illustrating a charged particle detection method 800 according to an embodiment of the present disclosure. Method 800 may be performed by using a charged particle beam device, such as electron beam tool 100, 100A, 100B, or 100C of FIGS. 1-2C. A charged particle detector, such as detector 644 of FIGS. 6A-D or detector 744 of FIGS. 7A-C, may be operated according to method 800. The method may be performed by a controller (e.g., controller 109 or image processing system 199).

[0086]

[0096] In step 801, a first exposure may be detected on a first detector area of ​​a detector. The first exposure may 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 may include an SEM scanning or other electron beam tool process. The first exposure may be performed under first exposure settings. For example, the first exposure settings may 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 another parameter that may affect the distribution of charged particle landing locations on the detector surface. The first detector area may include, for example, a first segment of a segmented charged particle detector. The first detector area may include a first noise parameter. For example, the first noise parameter may include a capacitance value of the first segment, such as a junction capacitance.

[0087]

[0097] In step 802, a second exposure may be detected on a second detector region of the detector. The second exposure may include, for example, a process similar to the first exposure, which may be detected at the second detector region to generate a second signal. The second exposure may be performed under second exposure settings. For example, the second exposure settings may 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 another parameter that may affect the distribution of charged particle landing locations on the detector surface. In some embodiments, the second exposure may be performed under the first exposure settings.

[0088]

[0098] The first exposure and the second exposure may occur simultaneously or at different times. For example, the first exposure and the second exposure may comprise a single scan, where the first exposure refers to the portion of the scan occurring over a first, smaller FOV and the second exposure refers to the portion of the scan occurring over a second, larger FOV. The first FOV and the second FOV may overlap. Alternatively, the first FOV and the second FOV may be located over different portions of the same or different sample surfaces.

[0089]

[0099] The second detector region may include, for example, not only the first segment of a segmented charged particle detector but also the second segment. 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 a capacitance value (such as a junction capacitance) of the first segment and the second segment.

[0090]

[0100] In steps 803 and 804, first and second images may be generated based on the first and second signals detected at the first and second detector regions, respectively. The first image may have higher accuracy than the second image. For example, the first signal may have a lower SNR ratio, e.g., due to a lower junction capacitance in the first detector region than in the second detector region. Alternatively, the second image may be preferable due to a higher collection rate of charged particles on the surface of the second detector region. A composite image may be generated based on the first and second images. In some embodiments, the second image may provide baseline information for monitoring the first image. For example, because the first detector region is relatively small, misalignment may cause fewer charged particles to be incident on the first detector region, resulting in a degraded first image. The second image may be used to monitor or correct this.

[0091]

[0101] The method 800 can be used to generate an optimal image within each FOV of a sample surface. The method can be used to generate an optimal image of an entire scan of a sample surface. A full scan may include, for example, a composite of a first image from a first detector area and a second image from a second detector area.

[0092]

[0102] Additional images may be generated according to method 800 simultaneously with the generation of the first and second images. For example, the entire detector surface (such as segments 650-653) may be used to generate images at the maximum acquisition rate.

[0093]

[0103] 9 is a flowchart illustrating a charged particle detection method 900 according to an embodiment of the present disclosure. Method 900 may be performed by using a charged particle beam device, such as electron beam tool 100, 100A, 100B, or 100C of FIGS. 1-2C. A charged particle detector, such as detector 644 of FIGS. 6A-D or detector 744 of FIGS. 7A-C, may be operated according to method 900. The method may be performed by a controller (e.g., controller 109 or image processing system 199).

[0094]

[0104] In step 901, exposure settings for a charged particle beam exposure process can be selected. The exposure process can be, for example, an electron beam exposure or other charged particle exposure in any of the apparatuses 100, 100A, 100B, or 100C of FIGS. 1-2C. The apparatus can further include a charged particle detector having first and second detector regions. For example, the detector can be, for example, detector 644 of FIGS. 6A-D or detector 744 of FIGS. 7A-C. The exposure settings can include parameters that can affect the spatial distribution of charged particles arriving at the detector surface. For example, the parameters can include FOV size, landing energy, aperture size, beam current, lens / deflector settings, ICU tilt angle settings, or another parameter that can affect the spatial distribution. The exposure settings can be adjustable or fixed parameters. In the latter case, selecting the exposure settings can occur during the design of the exposure apparatus.

[0095]

[0105] In step 902, a detector region of the detector may be selected based on the exposure settings selected in step 901. For example, based on the selected exposure settings, it may be determined that a sufficient percentage (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 in a first detector region. In this case, the first detector region may be selected for imaging. Alternatively, it may be determined that a higher collection rate may be required. In this case, a second detector region may be selected. The second detector region may include the first detector region and another region outside the first detector region.

[0096]

[0106] In step 903, a charged particle exposure process can be performed by using an apparatus such as that discussed in step 901. The charged particle exposure process can include selected exposure settings. Detection can be performed at a selected detection region such as that discussed in step 902 to generate a detection signal at the selected detection region. The detection can generate a detection signal having a favorable balance between SNR and collection rate.

[0097]

[0107] In step 904, an image may be generated based on the detected signal from the detector, which may have greater accuracy than an image that may be generated for a given exposure setting based on signals from another detector region of the detector.

[0098]

[0108] The steps presented above in methods 800 and 900 are not necessarily performed in the order presented, and may be performed simultaneously or in an order other than that presented above. As an example, step 802 may be performed before or simultaneously with step 801. Step 902 may be performed after or simultaneously with step 903 or 904.

[0099]

[0109] 10A-C show cross-sectional views of a portion of a charged particle detector 1044 according to some embodiments of the present disclosure. The charged particle detector 1044 can be, for example, an electron detector configured for use in an SEM or other electron beam device, such as the device according to FIGS. 1-2C. As shown on the left side of FIG. 10A, the charged particle detector 1044 can include a segmented detector as discussed above with respect to FIGS. 6A-D. The detector 1044 can include, for example, a PIN diode-type charged particle detector. The detector 1044 can be, for example, about 20 millimeters (mm) in diameter. The detector 1044 can include an aperture 1045 (such as 145 in FIG. 2C or 645 in FIGS. 6A-D) having a diameter of, for example, about 2-4 mm, through which the primary charged particle beam 1005 passes.

[0100]

[0110] As shown in FIG. 10A , the detector 1044 may include an upper conductive layer 1061 on the front surface (e.g., the surface facing the sample and thus configured to receive emitted charged particles) and a lower conductive layer 1065 on the back surface (i.e., the surface not facing the sample and therefore not configured to receive emitted charged particles). The upper conductive layer 1061 may include, for example, an aluminum layer. The upper conductive layer 1061 may not only improve series resistance but also reflect any stray light (e.g., light coming from the laser and scattered inside the column of the SEM system). The upper conductive layer 1061 may be configured as an electron incident surface. The upper conductive layer 1061 may form the sensor surface of the detector 1044. The upper conductive layer 1601 may include an upper electrode of the detector 1044. The lower conductive layer 1065 may include, for example, a titanium-gold layer. For example, the lower conductive layer 1065 may include a lower electrode of the detector 1044.

[0101]

[0111] The detector 1044 may include a semiconductor region 1060 between an upper conductive layer 1061 and a lower 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 p-doped and n-doped regions on the silicon. The p+ region may include a p-type dopant (e.g., 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 terminals of a PIN diode. Alternatively, the region 1062 may include an n+ region, and the region 1064 may include a p+ region.

[0102]

[0112] In operation, detector 1044 may provide the functionality to generate an electrical signal in response to a charged particle arrival event. Incoming charged particles, such as emitted electrons 1071 from a sample (such as sample 1050 in FIG. 10B ), may pass through top conductive layer 1061 and enter a depletion region in intrinsic region 1063. The incoming electrons may interact with the material of intrinsic region 1063 and generate electron-hole charge carrier pairs. The electrons and holes of the generated electron-hole pairs may be guided by internal electric fields within detector 1044 toward p+ region 1062 and n+ region 1040 for collection at the top and bottom electrodes, thereby generating a current indicative of the charged particle arrival event.

[0103]

[0113] A "dead area" or non-sensitive region 1002 may surround the aperture 1045 at the front surface of the detector 1044. The non-sensitive region 1002 may comprise, for example, a layer of SiO2 or another oxide or non-conductive material. One issue that has a direct impact on the performance of a charged particle detector is the spatial extent of the non-sensitive region 1002 around the aperture 1045. Ideally, this non-sensitive region 1002 should be as small as possible, since the emitted electron 1071 distribution may in some cases be highly concentrated around the aperture 1045 (see, for example, the distribution of emitted electrons 171 around the hole 145 in FIG. 2C ). Thus, for the case where most emitted electrons arrive at the center of the detector 1044, the proportion of electrons detected decreases with increasing size of the non-sensitive region 1002. Therefore, it may be desirable to reduce any "dead area" within the detector 1044 as much as possible to improve its overall efficiency or sensitivity. However, a limitation to reducing this "dead area" is the lateral extent of the deep depletion region (e.g., due to reduced junction capacitance) required for fast detector response. For example, it may be desirable for the depletion layer not to reach the surface or sidewall 1055 abutting the aperture 1045 to prevent a significant increase in leakage current in the image channel of the aperture 1045 nearest the detector segment.

[0104]

[0114] Another challenge facing charged particle detectors is the buildup of charge on the detector's surface. For example, as seen in FIG. 10A , some high-energy emitted electrons 1071 may strike a non-conductive or low-conductivity surface (such as the non-sensitive region 1002 or the sidewall 1055). In some cases, the high-energy electrons may cause more electrons to be emitted rather than accumulated, leading to a net positive charge buildup at the surface. This may increase noise in the image channel and create asymmetries in the electric field near the path of the main charged particle beam 1005, leading to beam shifts, image aberrations, and other errors. To reduce these effects, the charged particle detector 1044 may be provided with a conductive material layer along the sidewall 1055 abutting the aperture 1045. For example, the Ti / Au material of the lower conductive layer 1065 may be extended to another n+ region 1064a above the sidewall 1055 to smooth out the charge imbalance along the sidewall 1055. However, a problem exists, as shown in the close-up view of the sidewall 1055 in FIG. 10A. Due to surface roughness and manufacturing imperfections of the intrinsic region 1063, the bottom conductive layer 1065 may exhibit non-uniformity along the sidewall 1055. This may result in thickness variations not only in the Ti / Au material but also in the exposed portion of the intrinsic region 1063. Therefore, an asymmetry in the electric field near the path of the primary charged particle beam 1005 may persist. In addition, the separate n+ region 1064a may cause high leakage current due to its proximity to the p+ region 1060.

[0105]

[0115] Another way to minimize the above issues may include extending the doping profile of the n+ region 1064 from the rear surface of the detector 1044 along the sidewalls 1055 to the front surface in the non-sensitive region 1002, as shown in FIG. 10B. This may further reduce the field asymmetry within the aperture 1045, but does not solve the leakage current problem. And it fails to address the increased charge generated in the non-sensitive region 1002 or the corresponding reduction in efficiency and sensitivity. These issues may be particularly problematic when an ICU is not in use.

[0106]

[0116] For example, FIG. 10C schematically illustrates the relationship between the ICU 1066 and cross-sectional portions of the sample 1050 and detector 1044. The ICU 1066 can be configured to impart a tilt angle to the emitted electrons 1071. The ICU 1066 can include, for example, multiple coils in which a high current is generated. In this manner, the emitted electrons can be deflected away from the center of the aperture 1045 so that more electrons land on the detection surface. For example, in the plane of FIG. 10C, the ICU 1066 can deflect the first emitted electron 1071a and the second emitted electron 1071b away from the aperture 1045 so that more emitted electrons land on the detection surface of the upper conductive layer 1061. Without the ICU 1066, the majority of emitted electrons may be emitted with such low divergence that they pass directly back through the aperture 1045 (as shown by emitted electron 171c), or more electrons may impinge on the non-sensitive region 1002, significantly reducing collection efficiency and increasing charge-induced noise. However, due to the electric field generated by the high current in its coil, the ICU may generate its own noise and other aberrations. Therefore, it may be desirable to eliminate the ICU while maximizing collection efficiency and minimizing noise and other charging effects.

[0107]

[0117] Some embodiments of the present disclosure provide a charged particle detector that can maximize charged particle collection efficiency while minimizing unwanted charging effects. Charged particle detectors according to embodiments of the present disclosure may enable the elimination of an ICU from a charged particle device, further reducing noise and improving image quality. Figures 11A-B show cross-sectional views of a portion of a charged particle detector 1144 according to some embodiments of the present invention. The charged particle detector 1144 may be similar to, for example, the charged particle detector 1044, except as described below.

[0108]

[0118] 11A , the charged particle detector 1144 may include an upper conductive layer 1161, a semiconductor region 1160, a lower conductive layer 1165, and a non-sensitive region 1102. The semiconductor region 1160 may include, for example, a first doped region 1162, an intrinsic region 1163, and a second doped region 1164. As shown, the first doped region 1162 may include a p+ region, and the second doped region 1164 may include an n+ region. However, in some embodiments, the first doped region 1162 may include an n+ region, and the second doped region 1164 may include a p+ region. In general, the first doped region 1162 may have a different conductivity type than the second doped region 1164. For example, if one doped region is an n-doped type, such as n, n+, or n++, the other doped region may be a p-doped type, such as p, p+, or p++ type. The first doped region 1162 may extend from the front (detection) surface of the semiconductor region 1060 into the sidewall 1155 abutting the aperture 1145. The first doped region 1162 may extend along the sidewall 1155 abutting the aperture 1145 to the non-sensitive region 1102 (e.g., comprising a layer of SiO2 or other material as discussed above). The top conductive layer 1161 may extend to the edge 1167 of the aperture 1145 as shown in FIG. 11A. Alternatively, as shown in FIG. 11B, the top conductive layer 1161 may extend along the sidewall 1155 abutting the aperture 1145 to improve series resistance therein. 11A or 11B, a "dead area" can be realized at the rear (non-detecting) surface of the detector 1144, where a large depletion region between the first doped region 1162 and the second doped region 1164 must be maintained. For example, the non-sensitive region 1102 can extend from the first doped region 1162 and contact at least one of the second doped region 1164 or the lower conductive layer 1165. The arrangements of Figures 11A-B can yield numerous advantages for collection efficiency, detector speed, imaging performance, and noise reduction.

[0109]

[0119] For example, by relocating the non-sensitive region 1102 to the rear surface, the detection surface of the front side of the detector 1144 can be increased, as can the area that can receive the highest concentration of emitted electrons 1171, thereby greatly improving collection efficiency. For example, as seen in FIGS. 11A-B , the detection surface can extend all the way to the edge 1167 of the aperture 1145 itself (e.g., the entire periphery of the edge 1167 of the aperture 1145). Thus, electrons emitted to any part of the front surface can be collected within the central region of the detector 1144. At the same time, charging errors can be reduced in that the non-sensitive region 1102 is not illuminated. Thus, moving the non-sensitive region 1102 to the rear surface not only increases collection efficiency, but also reduces noise, beam shift, and other charging effects.

[0110]

[0120] Furthermore, the collection efficiency can be improved in view of the fact that the first doped region 1162 extends along the sidewall 1155 abutting the aperture 1145. This creates another detection surface on the sidewall 1155. Thus, even emitted electrons 1171 entering the aperture 1145 can be collected if they collide with the sidewall 1155. At the same time, the doped surface of the sidewall 1155 can act as a charge buildup prevention function so that the asymmetry of the electric field can be reduced. Therefore, beam shift, aberrations and other imaging errors can be further improved while the collection efficiency is further increased.

[0111]

[0121] In some embodiments, the detection area can be further increased by shrinking the diameter of aperture 1145, for example, compared to aperture 1045 of FIGS. 10A-C. For example, aperture 1045 can have a diameter of, for example, 2-4 mm, while aperture 1145 can have a diameter of, for example, 200-400 μm. This feature can also serve several purposes. First, as already mentioned, the effective detection surface area on the front surface of detector 1144 can be increased by shrinking the aperture diameter. Second, not only reducing the aperture diameter but also adding sidewall detection surfaces can make an ICU unnecessary. For example, it may no longer be necessary to tilt emitted electrons 1171 away from the center of detector 1144, since relatively fewer emitted electrons will enter aperture 1145 and even fewer will exit. Instead, most emitted electrons 1171 can be received either at the front surface of top conductive layer 1161 or on the sidewalls 1155. Thus, the ICU can be abandoned, eliminating a strong noise source.

[0112]

[0122] The reduction of the aperture 1145 and the relocation of the non-sensitive region 1102 each provide additional degrees of freedom in optimizing the lateral extent of the depletion region between the first doped region 1162 and the second doped region 1164. This can be most easily understood by comparing the perspective views of the left detector 1144 in FIGS. 10A-B with the perspective views of the left detector 1144 in FIGS. 11A-B. In the detector 1044, the design of the outer diameter of the non-sensitive region 1002 may be constrained by the need to maintain a small dead area. Meanwhile, the design of the inner diameter of the non-sensitive region 1002 may be constrained by the need to provide a sufficiently large aperture size to minimize the effect of electric field asymmetry on the main charged particle beam 1005. Thus, the maximum dimension of the depletion region between the separate n+ region 1064a and the p+ region 1062 is limited. This can lead to increased junction capacitance, slower detection response, and higher leakage current. However, the non-sensitive region 1102 within the detector 1144 is not so limited. 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 unacceptable asymmetry in the electric field in the primary charged particle beam 1105. Thus, the separation between the first and second doped regions can be increased even for a non-sensitive region 1102 of exactly the same diameter as that of the non-sensitive region 1002. However, because the non-sensitive region 1102 is on the rear surface of the detector 1144, its size can be increased without loss of detection surface area or increase in charging effects. Furthermore, as seen in FIGS. 11A-B , the non-sensitive region 1102 can overlap other upper boundaries, such as by crossing adjacent detector segments, without any substantial design complexity. Therefore, the non-sensitive region 1102 can be made larger to achieve reduced junction capacitance, faster detection response, and smaller leakage current. For example, even if the aperture 1145 is, for example, 200 μm to 1 mm in diameter, the non-sensitive region 1102 can have an outer diameter of, for example, 4, 6, or 8 mm.

[0113]

[0123] Furthermore, while the cross-sectional configurations near the detector aperture have been disclosed with respect to segmented detectors, such as those of Figures 6A-D, embodiments of the present disclosure are not limited thereto. For example, in some embodiments, the cross-sectional configurations of Figures 10A-11B may be arranged with other detectors (such as monolithic surface detectors of the type shown in Figures 3A-D, or segmented surface detectors), pixelated arrays of segments, or other detector arrangements.

[0114]

[0124] Some embodiments of the present disclosure may be further described using the following clauses: 1. A segmented multi-channel detector including a first detector region having a first segment; and a second detector region having the first segment and a 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 of clause 1, wherein the noise parameter is a capacitance. 3. The segmented multi-channel detector of clause 1, wherein the noise parameter is junction capacitance. 4. The segmented multi-channel detector of clause 1, wherein the second segment completely surrounds the first segment. 5. The segmented multi-channel detector of clause 1, wherein the first segment has a rectangular base shape. 6. The segmented multi-channel detector of clause 4, wherein the rectangular base shape is a square base shape. 7. A segmented multi-channel detector as described in clause 1, wherein the first segment has a dimension in a first direction of at least 1 mm. 8. A segmented multi-channel detector as described in clause 1, wherein the shape of the first detector region corresponds to the shape of a first FOV on a sample surface in a charged particle beam device. 9. The segmented multi-channel detector of clause 8, wherein the shape of the second detector region corresponds to the shape of a second FOV on a sample surface in the charged particle beam device, the second FOV being larger than the first FOV. 10. The segmented multi-channel detector of clause 1, further comprising: a third segment bordering at least a first side of the second detector region; and a fourth segment bordering at least a second side of the second detector region, the second side facing the first side. 11. The segmented multi-channel detector of clause 1 further comprising an aperture located outside the first segment. 12. A segmented multi-channel detector as described in clause 9, wherein the aperture is located within the second segment. 13. A charged particle beam device comprising: a charged particle beam source configured to generate a beam of primary charged particles; charged particle optics configured to scan the beam of primary charged particles across a field of view (FOV) of a sample surface; and a segmented multi-channel detector as described in clause 1. 14. A charged particle beam device according to clause 13, wherein the shape of the first detector region corresponds to the shape of the FOV on the sample surface. 15. A charged particle beam device according to clause 13, wherein the shape of the second detector region corresponds to the shape of the FOV on the sample surface. 16. A charged particle beam device according to clause 13, wherein the first detector region is configured to capture more than 90% of the emitted charged particles from a scan of the beam over the FOV of the sample surface. 17. A charged particle beam device according to clause 13, wherein the second detector region is configured to capture more than 90% of the emitted charged particles from a scan of the beam over the FOV of the sample surface. 18. A method for detecting charged particle events in a charged particle detector, comprising: performing a first scan of a sample surface with a charged particle beam under a first exposure setting to cause emitted charged particles from the sample surface to land in a first detector area of ​​the charged particle detector, the first detector area including a first noise value of a noise parameter; performing the first scan; generating a first image based on the first scan; performing a second scan of the sample surface with the charged particle beam under a second exposure setting to cause emitted charged particles from the sample surface to land in a second detector area of ​​the charged particle detector, the second detector area 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, wherein the first image has higher precision than the second image, and the first detector area includes a first segment of the charged particle detector; the second detector area includes the first segment and a second segment of the charged particle detector; and the second detector area is larger than the first detector area. 19. The method of clause 18, wherein the noise parameter is capacitance. 20. The method of clause 18, wherein the noise parameter is junction capacitance. 21. The method of clause 18, wherein the second segment surrounds at least 50% of the first segment. 22. The method of clause 21, wherein the second segment completely surrounds the first segment. 23. The method of clause 18, wherein the first segment has a generally rectangular base shape. 24. The method of clause 23, wherein the substantially rectangular base shape is a substantially square base shape. 25. The method of clause 18, wherein the first segment has a dimension in a first direction of at least 1 mm. 26. The method of clause 18, wherein the shape of the first detector region corresponds to the shape of the FOV on the sample surface in the first scan. 27. The method of clause 18, wherein the shape of the second detector region corresponds to the shape of the FOV on the sample surface in the second scan. 28. The method of clause 18, further comprising: detecting charged particles in a third segment that borders at least a first side of the second detector area; detecting charged particles in a fourth segment that borders at least a second side of the second detector area, the second side facing the first side; and determining alignment parameters based on the detected charged particles in the third segment and the fourth segment. 29. The method of clause 18, wherein the charged particle detector includes an aperture located outside the boundary of the first segment. 30. The method of clause 29, wherein the aperture is located within the second segment. 31. The method of clause 18, wherein the first exposure setting or the second exposure setting includes one of an FOV size, a landing energy, a beam aperture setting, a beam current, a lens setting, a deflector setting, and an image frequency compensation unit setting. 32. The method of clause 18, wherein the first exposure setting includes a first FOV size; the second exposure setting includes a second FOV size; and the second FOV size is larger than the first FOV size. 33. The method of clause 18, wherein the first exposure setting comprises a first landing energy; the second exposure setting comprises a second landing energy; and the second landing energy is higher than the first landing energy. 34. The method of clause 18, wherein the first exposure setting includes a first beam aperture setting; the second exposure setting includes a second beam aperture setting; and the second beam aperture setting is larger than the first beam aperture setting. 35. The method of clause 18, wherein the first exposure setting comprises a first beam current; the second exposure setting comprises a second beam current; and the second beam current is greater than the first beam current. 36. The method of clause 18, wherein the first detector region captures more than 90% of the emitted charged particles from the first scan. 37. The method of clause 18, wherein the second detector area captures more than 90% of the emitted charged particles from the second scan. 38. A non-transitory computer-readable medium storing a set of instructions executable by at least one processor of an apparatus, the set of instructions causing the apparatus to perform a method including: performing a first scan of a sample surface with a charged particle beam under a first exposure setting to cause emitted charged particles from the sample surface to land within a first detector area of ​​a charged particle detector, the first detector area including a first noise value of a noise parameter; generating a first image based on the first scan; and detecting the emitted charged particles from the sample surface to land within a first detector area of ​​a charged particle detector. performing a second scan of the sample surface with the charged particle beam under a second exposure setting to land within a second detector area, the second detector area including a second noise value of the noise parameter, and 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 higher precision than the second image, the first detector area including a first segment of the charged particle detector; the second detector area including the first segment and a second segment of the charged particle detector; and the second detector area being larger than the first detector area. 39. A method for detecting charged particle events in a charged particle detector, comprising: selecting an exposure setting for a charged particle beam exposure device; selecting a first detector area or a second detector area of ​​the charged particle detector based on the exposure setting; performing a charged particle beam exposure under the selected exposure setting; and generating an image based on charged particle detection in the selected first detector area or second detector area, wherein the first detector area includes a first segment of the charged particle detector and includes a first noise value of a noise parameter, and the second detector area includes the first segment and a second segment of the charged particle detector and includes a second noise value of the noise parameter, the second noise value being higher than the first noise value, and the second detector area being larger than the first detector area. 40. A non-transitory computer-readable medium storing a set of instructions executable by at least one processor of an apparatus, the set of instructions causing the apparatus to perform a method including: selecting an exposure setting for a charged particle beam exposure apparatus; selecting a first detector area or a second detector area of ​​a charged particle detector based on the exposure setting; performing a charged particle beam exposure under the selected exposure setting; and generating an image based on charged particle detection in the selected first detector area or second detector area, wherein the first detector area includes a first segment of the charged particle detector and includes a first noise value of a noise parameter, and the second detector area includes the first segment and a second segment of the charged particle detector and includes a second noise value of the noise parameter, the second noise value being higher than the first noise value, and the second detector area being larger than the first detector area. 41. A charged particle detector comprising: an upper conductive layer including a detection surface; a lower conductive layer; a semiconductor region between the upper and lower conductive layers, the semiconductor region including a first doped region of a first conductivity type adjacent to the upper conductive layer, a second doped region of a second conductivity type different from the first conductivity type adjacent to the lower 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 therethrough, wherein the detection surface extends to an edge of the aperture. 42. A charged particle detector according to clause 41, wherein the detection surface extends to the entire perimeter of the edge of the aperture. 43. A charged particle detector as defined in clause 41, wherein the sidewall abutting the aperture includes another detection surface. 44. A charged particle detector according to clause 41, wherein the first doped region extends along the detection surface and along a sidewall of the aperture. 45. A charged particle detector as defined in clause 44, wherein the first doped region extends to a non-sensitive surface comprising a non-conductive material. 46. ​​A charged particle detector as described in clause 41, further comprising a non-sensitive surface comprising a non-conductive material, the non-sensitive surface surrounding the aperture and in contact with one of the lower conductive layer or the second doped region. 47. A charged particle detector according to clause 46, wherein the non-sensitive surface comprises silicon dioxide (SiO2). 48. A charged particle detector as described in clause 46, wherein the non-sensitive surface comprises an outer diameter of 4 to 8 mm. 49. A charged particle detector as described in clause 41, wherein the aperture comprises a diameter of 200 to 400 µm. 50. The charged particle detector of clause 41, wherein the top conductive layer comprises aluminum (Al). 51. The charged particle detector of clause 41, wherein the lower conductive layer comprises one of titanium (Ti) or gold (Au). 52. A charged particle detector as set forth in clause 41, wherein the top conductive layer extends along a sidewall of the aperture. 53. The charged particle detector of clause 41, wherein the first doped region comprises a p-type dopant. 54. A charged particle detector according to clause 53, wherein the p-type dopant comprises boron. 55. The charged particle detector of clause 41, wherein the second doped region comprises an n-type dopant. 56. A charged particle detector according to clause 55, wherein the n-type dopant comprises one of arsenic, phosphorus or antimony.

[0115]

[0125] A non-transitory computer-readable medium may be provided that stores instructions for a processor of a controller (e.g., controller 109 of FIG. 1 or 2B or image processing system 199 of FIG. 2B) for detecting charged particles according to, for example, the exemplary flowcharts of FIGS. 8-9 according to some embodiments of the present invention. For example, the instructions stored in the non-transitory computer-readable medium may be executed by circuitry of the controller to perform some or all of method 800 or method 900. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, a hard disk, a solid-state drive, a magnetic tape or any other magnetic data storage medium, a compact disk read-only memory (CD-ROM), any other optical data storage medium, any physical medium having a pattern of holes, random access memory (RAM), programmable read-only memory (PROM), 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, and network-connected versions thereof.

[0116]

[0126] 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 diagrams may represent an arithmetic or logical operation that can be implemented using hardware, such as electronic circuits. A block may also represent a module, segment, or portion of code that includes one or more executable instructions for implementing the specified logical function(s). It should be understood that in some alternative implementations, the functions shown in the blocks may occur out of the order depicted in the figures. For example, two blocks shown in succession may be executed or performed substantially simultaneously, or 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 and combination of blocks in the block diagrams can be implemented by a special-purpose hardware-based system that performs the specified functions or acts, or by a combination of special-purpose hardware and computer instructions.

[0117]

[0127] It will be understood that embodiments of the present disclosure are not limited to the exact structure described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. For example, a charged particle inspection system may be just one example of a charged particle beam system according to embodiments of the present disclosure.

Claims

1. a first detector region having a first segment; and a second detector area having the first segment and a second segment, the second segment surrounding at least 50% of the first segment; 1. A segmented multi-channel detector comprising: the one detector region includes a first noise value of a noise parameter; 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 of claim 1 , wherein the noise parameter is capacitance.

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

4. The segmented multi-channel detector of claim 1 , wherein the second segment completely surrounds the first segment.

5. The segmented multi-channel detector of claim 1 , wherein the first segment has a rectangular base shape.

6. The segmented multi-channel detector of claim 4 , wherein the rectangular base shape is a square base shape.

7. The segmented multi-channel detector of claim 1 , wherein the first segment has a dimension in a first direction of at least 1 mm.

8. 10. The segmented multi-channel detector of claim 1, wherein the shape of the first detector area corresponds to the shape of a first FOV on a sample surface in a charged particle beam device.

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

10. a third segment bordering at least a first side of the second detector region; and a fourth segment that borders at least a second side of the second detector area, the second side facing the first side; The segmented multi-channel detector of claim 1 further comprising:

11. The segmented multi-channel detector of claim 1 further comprising an aperture located outside the first segment.

12. The segmented multi-channel detector of claim 9 , wherein the aperture is located within the second segment.

13. a charged particle beam source configured to generate a beam of primary charged particles; charged particle optics configured to scan the beam of primary charged particles across a field of view (FOV) of a sample surface; and 10. The segmented multi-channel detector of claim 1 A charged particle beam device comprising:

14. 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. 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.

Images