Beam Array Geometry Optimizer for Multi-Beam Detection Systems

Abstract

Apparatus, systems, and methods for optimizing the geometry of a beam array for a multi-beam inspection tool are disclosed. In some embodiments, a microelectromechanical system (MEMS) may include a first row of apertures; a second row of apertures located below the first row of apertures; a third row of apertures located below the second row of apertures; and a fourth row of apertures located below the third row of apertures; wherein the first row of apertures, the second row of apertures, the third row of apertures, and the fourth row of apertures are parallel to each other in a first direction; the first row of apertures and the third row of apertures are offset from the second row of apertures and the fourth row of apertures in a second direction perpendicular to the first direction; the first row of apertures and the third row of apertures have a first length; the second row of apertures and the fourth row of apertures have a second length; and in the second direction, the first length is longer than the second length.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Application 62 / 985,669, filed March 5, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The description in this paper relates to the field of charged particle beam systems, and more specifically to beam array geometry optimization for multi-beam inspection systems. Background Technology

[0004] In the manufacturing process of integrated circuits (ICs), incomplete or completed circuit components are inspected to ensure they are manufactured according to the design and free of defects. Inspection systems utilizing optical microscopes or charged particle (e.g., electron) beam microscopes, such as scanning electron microscopes (SEM), can be used. SEM transfers low-energy (e.g., <1 keV) or high-energy electrons to a surface and uses a detector to record secondary or backscattered electrons leaving the surface. By recording such electrons at different excitation locations on the surface, images with nanometer-scale spatial resolution can be created.

[0005] SEM can be a single-beam system or a multi-beam system. A single-beam SEM uses a single electron beam to scan the surface, while a multi-beam SEM uses multiple electron beams to scan the surface simultaneously. Compared to a single-beam system, a multi-beam system can achieve higher imaging throughput. However, multi-beam systems also have a more complex structure, thus lacking a certain degree of structural flexibility. Due to their higher complexity, optimizing the imaging throughput in a multi-beam system can be difficult. Summary of the Invention

[0006] Embodiments of this disclosure provide apparatus, systems, and methods for optimizing the geometry of a beam array for a multi-beam inspection tool. In some embodiments, a microelectromechanical system (MEMS) may include a first row of apertures; a second row of apertures; a third row of apertures; and a fourth row of apertures; wherein the first row of apertures, the second row of apertures, the third row of apertures, and the fourth row of apertures are parallel to each other in a first direction; the first row of apertures and the third row of apertures are offset from the second row of apertures and the fourth row of apertures in a second direction perpendicular to the first direction; the first row of apertures and the third row of apertures have a first length; the second row of apertures and the fourth row of apertures have a second length; and in the second direction, the first length is longer than the second length.

[0007] In some embodiments, a MEMS structure may include a first structure and a second structure. The first structure includes a first row of apertures; a second row of apertures located below the first row of apertures; a third row of apertures located below the second row of apertures; and a fourth row of apertures located below the third row of apertures. The first, second, third, and fourth rows of apertures are parallel to each other in a first direction. The first and third rows of apertures are offset from the second and fourth rows of apertures in a second direction perpendicular to the first direction. The first and third rows of apertures have a first length. The second and fourth rows of apertures have a second length. In the second direction, the first length is longer than the second length. The second structure includes an array of apertures forming a hexagonal shape. The first structure is superimposed on the second structure.

[0008] In some embodiments, a charged particle multi-beam system for generating multiple beams for inspecting a wafer positioned on a stage may include a first structure and a second structure. The first structure may include a first row of apertures; a second row of apertures; a third row of apertures; and a fourth row of apertures; wherein the first, second, third, and fourth rows of apertures are parallel to each other in a first direction; the first and third rows of apertures are offset from the second and fourth rows of apertures in a second direction perpendicular to the first direction; the first and third rows of apertures have a first length; the second and fourth rows of apertures have a second length; and in the second direction, the first length is longer than the second length. The second structure may include an array of apertures forming a hexagonal shape. The system may also include a controller comprising circuitry configured to perform continuous scan inspection using the first structure or skip scan inspection using the second structure. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0010] Figure 2 This illustrates embodiments consistent with the present disclosure. Figure 1 A schematic diagram of an exemplary multi-beam system, which is a part of an exemplary charged particle beam inspection system.

[0011] Figure 3A This is a graphical illustration of beam generation in a multi-beam system consistent with embodiments of the present disclosure.

[0012] Figure 3B This is a schematic diagram of a MEMS aperture array consistent with embodiments of this disclosure.

[0013] Figures 4A-4B This is a schematic diagram of an example aperture array used to generate beam waves.

[0014] Figure 4CThis is an example diagram showing the number of beams in different aperture arrays, which can be used to scan a wafer in a given FOV with different beam pitches.

[0015] Figures 5A-5C This is a schematic diagram of an example aperture array used to generate beam waves.

[0016] Figure 5D This is an example diagram of the fill factor in different aperture arrays, which can be used to scan a wafer in a given FOV with different beam pitches.

[0017] Figure 6A This is a schematic illustration of an example aperture array for generating beam waves, consistent with embodiments of this disclosure.

[0018] Figure 6B This is an example diagram of the number of beams in different aperture arrays consistent with embodiments of the present disclosure, which can be used to scan a wafer in a given FOV with different beam pitches.

[0019] Figure 7 This is a schematic illustration of an example aperture array for generating beam waves, consistent with embodiments of this disclosure.

[0020] Figure 8 This is an illustration of an example process for inspecting a wafer, consistent with embodiments of this disclosure. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein the same numerals in different drawings denote the same or similar elements unless otherwise stated. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with aspects relevant to the subject matter recited in the appended claims. For example, although some embodiments are described in the context of using electron beams, this disclosure is not limited thereto. Other types of charged particle beams can be applied similarly. Furthermore, other imaging systems, such as optical imaging, photoelectric detection, X-ray detection, etc., can be used.

[0022] Electronic devices consist of circuits formed on a piece of silicon called a substrate. Many circuits can be formed together on the same piece of silicon and are called integrated circuits or ICs. The size of these circuits has been reduced significantly, so more circuits can be assembled on the substrate. For example, an IC chip in a smartphone can be as small as a thumbnail but can include more than 2 billion transistors, each less than 1 / 1000th the size of a human hair.

[0023] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process, typically involving hundreds of individual steps. Even an error in a single step can result in a defective IC, rendering it useless. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process, i.e., to improve the overall yield of the process.

[0024] A component of improving yield is monitoring the chip manufacturing process to ensure it is producing a sufficient number of functional integrated circuits. One way to monitor this process is to inspect the chip's circuit structure at various stages of its formation. This inspection can be done using a scanning electron microscope (SEM). SEMs are used to image these extremely small structures, essentially taking "pictures" of the wafer's structure. These images can be used to determine if the structure is formed correctly and in the correct location. If defects are found, the process can be adjusted to make them less likely to recur.

[0025] A Sequencing Electron Microscope (SEM) works similarly to a camera. A camera takes pictures by receiving and recording the brightness and color of light reflected or emitted from a person or object. A Sequencing Electron Microscope (SEM) takes "pictures" by receiving and recording the energy or quantity of electrons reflected or emitted from a structure. Before taking such "pictures," an electron beam can be applied to the structure, and as electrons are reflected or emitted from the structure ("ejected"), the SEM's detector receives and records the energy or quantity of those electrons to generate an image. To take such "pictures," some SEMs use a single electron beam (called a "single-beam SEM"), while others use multiple electron beams (called a "multi-beam SEM") to take multiple "pictures" of the wafer. By using multiple electron beams, the SEM can apply more electron beams to the structure to obtain these multiple "pictures," resulting in more electrons being emitted from the structure. Therefore, the detector can receive more emitted electrons simultaneously and generate images of the wafer's structure with greater efficiency and faster speed.

[0026] In multi-charged particle beam imaging systems (e.g., multi-beam SEM), an aperture array can be used to form multiple beams. The aperture array can include multiple through-holes (“apers”) that can split a single charged particle beam into multiple beams. The number of apertures in the aperture array can affect the throughput of the multi-charged particle beam imaging system. Throughput indicates how quickly an imaging system completes an inspection task per unit time. During inspection, the imaging system generates an image by scanning the surface of a sample. For defect inspection, an image can be generated from each beam. As more beams are generated from a single charged particle beam (e.g., more apertures in the aperture array), more images can be captured for scanning the sample. This can increase the throughput of the imaging system.

[0027] The geometry of the aperture array can affect the throughput of a multi-charged particle beam imaging system. However, multi-charged particle beam imaging systems are typically designed for specific applications requiring specific scan modes. An aperture array geometry that optimizes the throughput of the imaging system in one scan mode may not optimize the throughput of the imaging system in another scan mode. To accommodate different applications, multi-charged particle beam imaging systems can use aperture arrays with different geometries for different scan modes. The geometry of the aperture array can be selected based on its ability to optimize the throughput of the imaging system for a specific scan mode.

[0028] Some embodiments of this disclosure particularly provide methods and systems for optimizing the geometry of a beam array in a multi-beam inspection system. In some embodiments, the multi-beam system may use an aperture array having a first set of apertures and a second set of apertures, wherein the first set of apertures is arranged in a first two-dimensional (2D) shape, and the second set of apertures is arranged in a second 2D shape. The multi-beam inspection system can project a charged particle beam onto the different sets of apertures. The multi-beam inspection system can control the operation of the first and second sets of apertures in different pass-through or blockage states (or "modes"), etc. An aperture in a "pass-through" state allows the electron beam to pass through. An aperture in a "blockage" state blocks the electron beam. Apertures in other states can focus or bend the electron beam, etc. When the multi-beam inspection system projects a charged particle beam onto the first and second sets of apertures, the first and second sets of apertures can operate in either a pass-through or blockage state, such that the charged particle beam can be projected into the geometry of the first set of apertures or the geometry of the second set of apertures. Because the first and second sets of orifices have different geometries, the multi-beam inspection system can have multiple operating modes and adapt to a variety of applications that can optimize the throughput of the inspection system.

[0029] For clarity, the relative sizes of the components in the accompanying drawings may be exaggerated. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and differences are described only with respect to individual embodiments.

[0030] As used herein, unless otherwise expressly stated, the term "or" covers all possible combinations unless impractical. For example, if a component is declared to include A or B, then unless otherwise expressly stated or impractical, the component may include A, or B, or A and B. As a second example, if a component is declared to include A, B, or C, then unless otherwise expressly stated or impractical, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0031] Figure 1 An exemplary electron beam inspection (EBI) system 100 consistent with embodiments of this disclosure is shown. The EBI system 100 can be used for imaging. Figure 1 As shown, the EBI system 100 includes a main chamber 101, a loading / locking chamber 102, an electron beam tool 104, and an equipment front-end module (EFEM) 106. The electron beam tool 104 is located within the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include multiple additional loading ports. The first loading port 106a and the second loading port 106b receive a wafer front-opening transfer cassette (FOUP), which contains wafers to be inspected (e.g., semiconductor wafers or wafers made of multiple other materials) or samples (wafers and samples are interchangeable). A “batch” is a group of wafers that can be loaded as a batch for processing.

[0032] One or more robotic arms (not shown) in EFEM 106 can transport the wafer to loading / locking chamber 102. Loading / locking chamber 102 is connected to a loading / locking vacuum pump system (not shown), which removes gas molecules from loading / locking chamber 102 to achieve a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) can transport the wafer from loading / locking chamber 102 to main chamber 101. Main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from main chamber 101 to achieve a second pressure below the first pressure. After reaching the second pressure, the wafer is inspected by electron beam tool 104. Electron beam tool 104 can be a single-beam system or a multi-beam system.

[0033] Controller 109 is electrically connected to electron beam tool 104. Controller 109 may be a computer configured to perform various controls of EBI system 100. Although controller 109 is... Figure 1 The controller 109 is shown outside the structure including the main chamber 101, the loading / locking chamber 102, and the EFEM 106, but it is understood that the controller 109 may be part of the structure.

[0034] In some embodiments, controller 109 may include one or more processors (not shown). A processor may be a general-purpose or specific electronic device capable of manipulating or processing information. For example, a processor may include any number of central processing units (or “CPU”), graphics processing units (or “GPU”), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general-purpose array logic (GALs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), system-on-a-chip (SoCs), application-specific integrated circuits (ASICs), and any combination of any type of circuitry capable of data processing. A processor may also be a virtual processor, including one or more processors distributed across multiple machines or devices coupled via a network.

[0035] In some embodiments, controller 109 may also include one or more memories (not shown). The memory may be a general-purpose or specific electronic device capable of storing processor-accessible (e.g., via a bus) code and data. For example, the memory may include any number of random access memory (RAM), read-only memory (ROM), optical disc, magnetic disk, hard disk, solid-state drive, flash drive, secure digital card (SD card), memory stick, compact flash (CF) card, or any combination of any type of storage device. The code may include an operating system (OS) and one or more applications (or “apps”) for a specific task. The memory may also be virtual memory, including one or more memories distributed across multiple machines or devices coupled via a network.

[0036] Now for reference Figure 2 , Figure 2 This is a schematic diagram illustrating an exemplary electron beam tool 104 consistent with embodiments of the present disclosure, the exemplary electron beam tool 104 including as... Figure 1 This is a multi-beam inspection tool, part of the EBI system 100. The multi-beam electron beam tool 104 (also referred to herein as device 104) includes an electron source 201, a coulomb aperture plate (or “gun-hole plate”) 271, a converging lens 210, a source conversion unit 220, a main projection system 230, a motorized stage 209, and a sample holder 207 supported by the motorized stage 209 to hold a sample 208 (e.g., a wafer or photomask) to be inspected. The multi-beam electron beam tool 104 may also include an auxiliary projection system 250 and an electronic detection device 240. The main projection system 230 may include an objective lens 231. The electronic detection device 240 may include multiple detection elements 241, 242, and 243. A beam splitter 233 and a deflection scanning unit 232 may be positioned within the main projection system 230.

[0037] The electronic source 201, coulomb aperture plate 271, converging lens 210, source conversion unit 220, beam splitter 233, deflection scanning unit 232, and main projection system 230 can be aligned with the main optical axis 204 of device 104. The auxiliary projection system 250 and electronic detection device 240 can be aligned with the auxiliary optical axis 251 of device 104.

[0038] The electron source 201 may include a cathode (not shown) and an extractor or anode (not shown), wherein during operation, the electron source 201 is configured to emit primary electrons from the cathode and the primary electrons are extracted or accelerated by the extractor and / or anode to form a primary electron beam 202, the primary electron beam 202 forming a primary electron beam cross (virtual or real) 203. The primary electron beam 202 can be visualized as being emitted from the primary electron beam cross 203.

[0039] Source conversion unit 220 may include an imaging element array (not shown), an aberration compensator array (not shown), a beam-limiting aperture array (not shown), and a pre-bending micro-deflector array (not shown). In some embodiments, the pre-bending micro-deflector array deflects multiple primary beam waves 211, 212, 213 of the primary electron beam 202 to enter the beam-limiting aperture array, the imaging element array, and the aberration compensator array normally. In some embodiments, a converging lens 210 is designed to focus the primary electron beam 202 into a parallel beam and incident perpendicularly onto source conversion unit 220. The imaging element array may include multiple micro-deflectors or microlenses to influence the multiple primary beam waves 211, 212, 213 of the primary electron beam 202 and form multiple parallel images (virtual or real) of the primary beam cross 203, each of the primary beam waves 211, 212, and 213 having one parallel image. In some embodiments, the aberration compensator array may include a field curvature compensator array (not shown) and an astigmatism compensator array (not shown). The field curvature compensator array may include multiple microlenses to compensate for field curvature aberrations of primary beams 211, 212, and 213. The astigmatism compensator array may include multiple micro-astigmatists to compensate for astigmatic aberrations of primary beams 211, 212, and 213. The beam-limiting aperture array may be configured to limit the diameter of individual primary beams 211, 212, and 213. Figure 2 Three primary beams 211, 212, and 213 are shown as an example, and it should be understood that the source conversion unit 220 can be configured to form any number of primary beams. The controller 109 can be connected to... Figure 1 Various components of the EBI system 100, such as the source conversion unit 220, the electronic detection device 240, the main projection system 230, or the motorized stage 209. In some embodiments, as explained in further detail below, the controller 109 can perform various image and signal processing functions. The controller 109 can also generate various control signals for managing the operation of the charged particle beam inspection system.

[0040] Converging lens 210 is configured to focus primary electron beam 202. Converging lens 210 can also be configured to adjust the current in primary beams 211, 212, and 213 downstream of source conversion unit 220 by changing the focusing power of converging lens 210. Alternatively, the current can be changed by altering the radial size of a beam-limiting aperture within a beam-limiting aperture array corresponding to an individual primary beam. The current can be changed by altering both the radial size of the beam-limiting aperture and the focusing power of converging lens 210. Converging lens 210 can be an adjustable converging lens, which can be configured such that the position of its first principal plane is movable. The adjustable converging lens can be configured to be magnetic, which can cause off-axis beams 212 and 213 to irradiate source conversion unit 220 at a rotational angle. The rotational angle varies with the focusing power of the adjustable converging lens or the position of the first principal plane. The converging lens 210 may be an anti-rotation converging lens, which may be configured to maintain a constant rotation angle while the focusing power of the converging lens 210 changes. In some embodiments, the converging lens 210 may be an adjustable anti-rotation converging lens, wherein the rotation angle does not change when its focusing power and the position of its first principal plane change.

[0041] Objective lens 231 can be configured to focus beams 211, 212, and 213 onto sample 208 for examination, and in the current embodiment, three probe points 221, 222, and 223 can be formed on the surface of sample 208. Coulomb aperture 271 is configured in operation to block peripheral electrons of the primary electron beam 202 to reduce the Coulomb effect. The Coulomb effect can amplify the size of each of the probe points 221, 222, and 223 of the primary beams 211, 212, and 213, and thus degrade the examination resolution.

[0042] Beam splitter 233 may, for example, include generating electrostatic dipole fields and magnetic dipole fields. Figure 2 The Wien filter (not shown) is an electrostatic deflector. In operation, the beam splitter 233 can be configured to apply an electrostatic force to the individual electrons of the primary beams 211, 212, and 213 via an electrostatic dipole field. The electrostatic force is equal in magnitude but opposite in direction to the magnetic force applied to the individual electrons by the magnetic dipole field of the beam splitter 233. Therefore, the primary beams 211, 212, and 213 can pass through the beam splitter 233 at least substantially straight with a deflection angle of at least substantially zero.

[0043] Deflection scanning unit 232 is configured in operation to deflect primary beams 211, 212, and 213 to scan probe points 221, 222, and 223 across an individual scanning region on a portion of the surface of sample 208. In response to the incidence of primary beams 211, 212, and 213 or probe points 221, 222, and 223 on sample 208, electrons are emitted from sample 208, generating three secondary electron beams 261, 262, and 263. Each of the secondary electron beams 261, 262, 263, and 263 typically comprises secondary electrons (electron energy ≤ 50 eV) and backscattered electrons (electron energy between 50 eV and the landing energy of primary beams 211, 212, and 213). Beam splitter 233 is configured to deflect the secondary electron beams 261, 262, and 263 toward auxiliary projection system 250. The auxiliary projection system 250 then focuses the secondary electron beams 261, 262, and 263 onto the detection elements 241, 242, and 243 of the electron detection device 240. The detection elements 241, 242, and 243 are arranged to detect the corresponding secondary electron beams 261, 262, and 263 and generate corresponding signals, which are sent to the controller 109 or a signal processing system (not shown), for example, to construct an image of the corresponding scan area of ​​the sample 208.

[0044] In some embodiments, detection elements 241, 242, and 243 detect corresponding secondary electron beams 261, 262, and 263, respectively, and generate corresponding intensity signal outputs (not shown) to an image processing system (e.g., controller 109). In some embodiments, each detection element 241, 242, and 243 may include one or more pixels. The intensity signal output of the detection element may be the sum of signals generated by all pixels within the detection element.

[0045] In some embodiments, controller 109 may include an image processing system comprising an image acquirer (not shown) and a storage device (not shown). The image acquirer may include one or more processors. For example, the image acquirer may include a computer, server, mainframe, terminal, personal computer, any kind of mobile computing device, or a combination thereof. The image acquirer may be communicatively coupled to the electronic detection device 240 of device 104 via a medium such as an electrical conductor, fiber optic cable, portable storage medium, IR, Bluetooth, Internet, wireless network, radio, or a combination thereof. In some embodiments, the image acquirer may receive signals from the electronic detection device 240 and may construct an image. The image acquirer may thus acquire an image of sample 208. The image acquirer may also perform various post-processing functions, such as generating contours, overlaying indicators on the acquired image, etc. The image acquirer may be configured to perform adjustments such as brightness and contrast of the acquired image. In some embodiments, the memory may be a storage medium such as a hard disk, flash drive, cloud storage, random access memory (RAM), other types of computer-readable storage, etc. The storage device may be coupled to the image acquirer and may be used to save scanned raw image data as raw images and post-processed images.

[0046] In some embodiments, the image acquirer may acquire one or more images of a sample based on imaging signals received from the electronic detection device 240. The imaging signals may correspond to a scanning operation for imaging charged particles. The acquired image may be a single image comprising multiple imaging regions. The single image may be stored in a storage device. The single image may be an original image that can be divided into multiple regions. Each region may include an imaging region containing features of the sample 208. The acquired images may include multiple images of a single imaging region of the sample 208 sampled multiple times over a time series. The multiple images may be stored in a storage device. In some embodiments, the controller 109 may be configured to perform image processing steps on multiple images of the same location of the sample 208.

[0047] In some embodiments, the controller 109 may include measurement circuitry (e.g., an analog-to-digital converter) to acquire the distribution of detected secondary electrons. The electron distribution data collected during the detection time window, combined with corresponding scan path data of each of the primary beams 211, 212, and 213 incident on the wafer surface, can be used to reconstruct an image of the wafer structure being inspected. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208, and thus can be used to reveal any defects that may be present in the wafer.

[0048] In some embodiments, the controller 109 may control the motorized stage 209 to move the sample 208 during the examination of the sample 208. In some embodiments, the controller 109 may enable the motorized stage 209 to continuously move the sample 208 at a constant speed in one direction. In other embodiments, the controller 109 may enable the motorized stage 209 to change the speed of movement of the sample 208 over time according to the steps of the scanning process.

[0049] Although Figure 2 The device 104 is shown to use three primary electron beams, but it should be understood that the device 104 may use two or more primary electron beams. This disclosure does not limit the number of primary electron beams used in the device 104.

[0050] Compared to a single charged particle beam imaging system (“single-beam system”), a multi-charged particle beam imaging system (“multi-beam system”) can be designed to optimize throughput for different scanning modes. Embodiments of this disclosure provide multi-beam systems capable of optimizing throughput for different scanning modes by using beam arrays with different geometries to accommodate varying throughput and resolution requirements.

[0051] In some embodiments of this disclosure, an apparatus (e.g., a component implemented as source conversion unit 220) can be used to generate beam arrays arranged in different 2D geometries for a multi-beam inspection system. The apparatus may include at least one set of apertures in an aperture array, wherein each set of apertures includes a different 2D geometric arrangement of the apertures. The apparatus can be operated such that a primary charged particle beam (e.g., primary electron beam 202) can irradiate the aperture array based on a scanning mode. By adjusting one or more parameters of the primary charged particle beam (e.g., projected area), the primary charged particle beam can be incident on the aperture array according to the needs of different applications (e.g., scanning modes), wherein an optimal set of apertures in the aperture array can be selected, and optimal throughput results (e.g., maximum throughput) can be obtained for each application. Figure 3A Beam generation in a multi-beam system including such a device is illustrated. Figure 3A In the example embodiment shown, the multi-beam system can select a set of apertures for generating beam waves, and therefore can have the ability to optimize different scanning modes, including increasing the throughput of different scanning modes.

[0052] Figure 3A This is a graphical illustration of beam generation in a multi-beam system consistent with embodiments of this disclosure. For example, a first operating mode could be a scanning mode using a first set of apertures, while a second operating mode could be a scanning mode using a second set of apertures. Figure 3AIn this system, electron source 201 emits electrons. Coulomb aperture 271 blocks peripheral electrons 302 from the primary electron beam 202 to reduce the Coulomb effect. Converging lens 210 focuses the primary electron beam 202 into a parallel beam, which is then incident on the source conversion unit 220 in the normal direction. Converging lens 210 can be used in conjunction with... Figure 2 The adjustable converging lens is described in relation to the related parts. Figure 3A In this process, the first principal plane of the adjustable converging lens 210 can be adjusted to be closer to the electron source 201, thereby reducing the projection area of ​​the primary electron beam 202. That is, in Figure 3A In this way, the focusing power of the converging lens 210 can be enhanced.

[0053] Source conversion unit 220 may include an aperture array. The aperture array may include apertures 304, 306, and 308. Because the converging lens 210 reduces the projected area of ​​the primary electron beam 202, the primary electron beam 202 can be incident only on a portion of the apertures of the aperture array. For example, in Figure 3A In this configuration, the primary electron beam 202 projects only through apertures 304, 306, and 308. The apertures of the aperture array or related components can be controlled to operate in different pass-through or blocking states to enable or disable the passage of electrons from the primary electron beam 202 through selected apertures. An aperture or related component in the pass-through state allows the beam to pass through, while an aperture or related component in the blocking state prevents the beam from passing through. For example, the aperture array may include a first set of apertures having a first combination of apertures in either a pass-through or blocking state, and a second set of apertures having a second combination of apertures in either a pass-through or blocking state.

[0054] In some embodiments, the aperture array may be a microelectromechanical system (MEMS) aperture array, or the associated components may be MEMS, which may be part of a MEMS array, such as a MEMS aperture array. Each aperture of the MEMS aperture array may include a deflection structure (e.g., a magnetic coil, an electrode, or any electromagnetic beam deflection device) and a chopper aperture downstream of the deflection structure.

[0055] Figure 3B This is a schematic illustration of a MEMS aperture array 350 consistent with embodiments of the present disclosure. The aperture array 350 may include multiple deflection structures, including deflection structures 324, 326, and 328, corresponding to chopper apertures 330, 332, and 334, respectively. Figure 3BAs shown, each chopper aperture can have a hole aligned with the center of the opening of the corresponding deflection structure. The hole of the chopper aperture can be smaller than the opening of the deflection structure. The apertures of the aperture array 350 can be independently and individually controlled to be in a through state or a blocked state. For example, chopper aperture 330 is controlled to be in a through state, wherein the electron beam 336 entering the deflection structure 324 is guided straight through, and the electron beam 336 can exit the chopper aperture 330. Similarly, chopper aperture 332 is controlled to be in a through state, wherein the electron beam 338 entering the deflection structure 326 is guided straight through, and the electron beam 338 can exit the chopper aperture 332. For example, the chopper aperture 334 is controlled to be in a blocked state. In this blocked state, the deflection structure 328 guides the electron beam 340 to be blanked (e.g., deflected away from the entry direction and impacting the wall of the chopper aperture 334), and the electron beam 340 can be prevented from passing through the aperture of the chopper aperture 334. Depending on the 2D shape of the set of apertures associated with the scanning mode, the chopper aperture can be controlled to be in a blocked state. In some embodiments, the deflection structure may be part of one or more components separate from the aperture array.

[0056] It should be noted that Figure 3A The number of beams generated is determined by the output angle of the primary electron beam 202 and the passage or obstruction state of the aperture through which the primary electron beam 202 is projected. For example, in Figure 3A The primary electron beam 202 can project and cover apertures 304, 306, and 308. If all apertures 304, 306, and 308 operate in the through state, the number of generated beams is 3. If only a portion of apertures 304, 306, and 308 operate in the through state (e.g., only aperture 304 operates in the through state), the number of generated beams is less than 3 (e.g., 1). However, the upper limit of the number of generated beams can be limited by the output angle of the primary electron beam 202. For example, as... Figure 3A As shown, if the primary electron beam 202 only covers apertures 304, 306, and 308 at its maximum output angle, the upper limit of the number of generated beam waves can be 3.

[0057] As an example embodiment, such as Figure 3A and Figure 3B As shown, by controlling the pass-through or blocking states of orifice groups with different 2D shapes, the multi-beam system can switch between different operating modes to adapt to the varying throughput requirements of various applications. This design does not significantly increase the complexity of the multi-beam system and provides users with more application options in a single solution without incurring substantial costs.

[0058] like Figure 3AAs shown, source conversion unit 220 may include beam focusing, guiding, or deflecting components that can cause beams 314, 316, and 318 to converge and pass through a common region downstream of source conversion unit 220. It should be noted that... Figures 3A-3B The illustrations are merely for explaining the principles and describing exemplary embodiments of this disclosure, and actual apparatuses and systems may include more, fewer, or identical components compared to those shown, or have the same or different configurations and arrangements of the components.

[0059] This disclosure discloses apparatus and methods for optimizing beam array geometry in multi-beam systems. In some embodiments, the apparatus may be implemented as part of or associated with source conversion unit 220 or one or more components. For example, source conversion unit 220 may include one or more sets of aperture arrays for use in different scanning modes (e.g., skip scan mode, continuous scan mode) in a multi-beam system. A first set of apertures may enable a first set of beam waves to scan a wafer with a first geometry. A second set of apertures may enable a second set of beam waves to scan a wafer with a second geometry. In some embodiments, the aperture sets may be stacked on top of each other and configured to operate in the same pass-through or block-through state or different pass-through or block-through states. An aperture in the pass-through state allows a beam to pass through the aperture, and an aperture in the block-through state prevents a beam from passing through the aperture. In some embodiments, the pass-through or block-through state of the aperture may be independently controlled by circuitry of source conversion unit 220. In some embodiments, the aperture array may be a microelectromechanical system (MEMS) aperture array. In some embodiments, the circuitry may be a processor (e.g., Figure 1 The controller 109's processor), and the memory storing executable instructions (e.g., Figure 1 The controller 109's memory (or a combination thereof). Controlling the pass-through or block-through state of each group of apertures under different scanning modes ensures that only apertures with selected beam array geometry can be used in the corresponding scanning mode, while apertures with non-selected beam array geometry cannot be used, thus preventing errors in controlling the shape of the beam. It should be noted that a multi-beam system can operate in any number of any modes.

[0060] Accordingly, when the device includes two or more sets of apertures, and the multi-beam system is capable of operating in two or more scanning modes, different sets of apertures in the aperture array can be configured to operate in different pass-through or blockage states. In some embodiments, the pass-through or blockage states of different aperture sets can be independently controlled by the circuitry of the source conversion unit 220.

[0061] The size, position, and arrangement of the aperture groups of the aperture array of the device can be any configuration, as long as the primary charged particle beam can be controlled to be projected onto a group substantially in each operating mode of the multi-beam system. Figures 4A-4B , Figure 6A and Figure 7 This is a schematic diagram of an example aperture array for generating beams, consistent with embodiments of this disclosure. The aperture array can be used in... Figure 2 and Figures 3A-3B In the source conversion unit 220. In some embodiments, Figures 4A-4B , Figure 6A and Figure 7 The aperture array shown can be a MEMS aperture array.

[0062] Image acquisition using multi-beam tools can include using electron beam tools (e.g., Figures 1-2 The electron beam tool 104 generates multiple inspection beams and inspects the wafer to be inspected (e.g., Figure 2 The image acquisition unit can be configured to scan the inspection beam over the wafer surface in a pattern (e.g., a grating pattern) on the sample 208. Figure 2 The signal output by the detection device 240) is used to acquire an image of the first imaging region. The range of the electron beam scan can be limited by the field of view (FOV) of the electron beam tool, and therefore, the first imaging region can coincide with the FOV. To image another region, the wafer is subjected to a sample stage (e.g., Figure 2 The mobile stage 209 moves and scans over a new area of ​​the wafer. In skip scan mode, imaging can be performed in a specific area within the field of view (FOV), and after completion, the stage is moved and the process is repeated.

[0063] In continuous scanning mode, imaging can be performed continuously while a movable stage carries a wafer along the x and y directions. For example, the stage can move in continuous linear motion under a charged particle beam column. Simultaneously, a charged particle source (e.g., Figure 2 One or more charged particle beams (e.g., generated by an electron source 201) are generated. Figure 2 The primary beam (211, 212, or 213) can be linearly scanned back and forth along scan lines in a pattern, such as a grating pattern. Thus, one or more beams of charged particles are moved to cover the moving wafer in discrete stripe segments. Further information regarding continuous scanning using a multi-beam device can be found in U.S. Patent Application No. 62 / 850,461, the entire contents of which are incorporated herein by reference.

[0064] Figure 4AAn example aperture array 402A is shown, which has a set of apertures 404A (hereinafter referred to as a square aperture array) in a square pattern that can be used in source conversion unit 220. The points depicted in the shaded and unshaded portions represent the total number of possible beams that can scan a specific region of the wafer within the FOV at a given pitch (beam or center-to-center distance of the aperture). The fill factor of the aperture array's beam can be determined by calculating the fraction of the total number of possible beams in the wafer region within the FOV that can be used for scanning under the aperture array. For example, the fill factor could be the fraction of the points in the shaded square region out of the total number of points in the FOV. In multi-beam systems operating in skip scan mode (e.g., Figure 1 In the EBI system 100, the beam fill factor of the square aperture array 402A can be 64%.

[0065] Figure 4B An example aperture array 402B is shown, which has a set of apertures 404B (hereinafter referred to as a hexagonal aperture array) in a hexagonal pattern that can be used in the source conversion unit 220. Similar to... Figure 4A The points depicted in the shaded and unshaded regions represent the total number of possible beams that can scan a specific area of ​​the wafer within the FOV at a given pitch. The fill factor can be the fraction of the points in the shaded hexagonal region out of the total number of points in the FOV. In multi-beam systems operating in skip scan mode (e.g., Figure 1 In the EBI system 100, the beam fill factor using the hexagonal aperture array 402B can be 83%.

[0066] Figure 4C An example diagram is shown illustrating the number of beams that can be used to scan a wafer in a given FOV with different beam pitches in different aperture arrays. The horizontal axis represents the beam pitch in micrometers (“μm”), decreasing from left to right. The vertical axis represents the number of beams that can be used to scan a wafer in a given FOV. Curve 408C represents a square aperture array (e.g., with varying beam pitches) that can be used to scan a wafer in a given FOV. Figure 4A The square aperture array 402A) can be used to scan the number of beams of the wafer in a skip scan mode. Curve 410C represents the number of beams that can be used in a hexagonal aperture array (e.g., with varying beam pitch) to scan the wafer in a skip scan mode. Figure 4B The number of beams used in a hexagonal aperture array (402B) to scan the wafer in a skip scan mode. For example... Figure 4C As shown, the number of beams that can be used in any aperture array increases as the beam pitch decreases, because the number of beams that can be used in the aperture array increases as the distance between each aperture decreases.

[0067] In some embodiments, a multi-beam system can use a hexagonal aperture array 402B to scan a portion of a wafer and skip to scan another adjacent portion of the wafer (e.g., by using a cellular pattern for scanning the wafer). For example, a square aperture array with a beamp pitch of 210 μm can allow 169 beams to scan a wafer in a skip scan mode, while a hexagonal aperture array with a beamp pitch of 210 μm can allow 217 beams to scan a wafer in the same FOV using the same skip scan mode. Therefore, in a multi-beam system using a skip scan mode, the hexagonal aperture array 402B may be more desirable than the square aperture array 402A because the aperture array 402B results in higher imaging throughput.

[0068] Figure 5A , Figure 5B and Figure 5C Exemplary rotating hexagonal aperture arrays 502A, 502B, and 502C that can be used in the source conversion unit 220 are shown respectively. Figure 5D Example diagrams are shown of different aperture arrays that can be used to scan a wafer in a given FOV with different beam pitches. Hexagonal aperture arrays 502A, 502B, and 502C include aperture groups 504A, 504B, and 504C, respectively, with the beam pitch decreasing sequentially. For example, hexagonal aperture array 502A may have three beams along each edge of the aperture array, hexagonal aperture array 502B may have six beams along each edge of the aperture array, and hexagonal aperture array 502C may have nine beams along each edge of the aperture array. Although hexagonal aperture arrays increase the throughput of the imaging system compared to square aperture arrays when used in skip scan mode, hexagonal aperture arrays may not be preferred for continuous scan mode. Due to the shape of the hexagonal aperture arrays 502A, 502B, and 502C, using hexagonal aperture arrays in a multi-beam system operating in continuous scan mode results in unused beam regions 506A, 506B, and 506C during wafer scanning, because scans performed using beams in regions 506A, 506B, and 506C will overlap with previous scans performed using beams. In other words, regions 506A, 506B, and 506C are “unused” regions in the field of view (FOV). Furthermore, as the beam pitch decreases from hexagonal aperture array 502A to hexagonal aperture array 502C, the fill factor decreases in continuous scan mode (e.g., from 74% to 65% to 61%) due to the unused regions. Figure 5D Curve 510 is shown in the figure. Curve 508 represents the fill factor of the square aperture array with different beam pitches in continuous scanning mode. For example... Figure 5DAs shown, with the increase in the number of beams at each edge, a square aperture array may be preferable to a hexagonal aperture array for increasing imaging throughput (e.g., increasing the number of beams used to scan the wafer) when operating an imaging system in continuous scan mode. However, a square aperture array may not maximize imaging throughput in continuous scan mode.

[0069] Figure 6A An example aperture array 602A that can be used in source conversion unit 220 is shown, having a set of apertures 604A (hereinafter referred to as a serrated edge rectangular aperture array) in a rectangular pattern with serrated edges. For example, the serrated edge rectangular aperture array 602A may include a first row of apertures 605A and a second row of apertures 606A below the first row of apertures 605A. In some embodiments, the first row of apertures 605A may be longer than the second row of apertures 606A (e.g., having more apertures), while in some other embodiments, the first row of apertures 605A and 606A may have the same length but may be offset from each other. Figure 6A As shown, the first row of apertures 605A and the second row of apertures 606A can be offset from each other in the horizontal direction, thereby giving the aperture array 602A a serrated edge rectangular shape. The serrated edge rectangular aperture array 602A may include a plurality of first row apertures 605A and a plurality of second row apertures 606A, wherein the first row apertures 605A and the second row apertures 606A alternate in a direction perpendicular to the direction in which the rows 605A and 606A extend (e.g., horizontally) (e.g., vertically).

[0070] One advantage of using the zigzag-edged rectangular aperture array 602 is that unused areas are minimized when used in continuous scan mode. For example, in Figure 6A In the illustrated embodiment, when the serrated-edge rectangular aperture array 602 is rotated in a specific manner, there may be no unused area. Therefore, when used in continuous scan mode, the fill factor of the serrated-edge rectangular aperture array 602A in a multi-beam system can be higher than that of the hexagonal aperture array 502C due to the unused area of ​​the array 502C. That is, using the serrated-edge rectangular aperture array 602A can result in higher throughput of the imaging system when operating in continuous scan mode (e.g., a fill factor of 81%).

[0071] In some embodiments, the shape of the zigzag-edge rectangular aperture array 624A can be modified by increasing or decreasing the number of rows. For example, the zigzag-edge rectangular aperture array 624A may have more alternating rows than the zigzag-edge rectangular aperture array 602A, wherein each alternating row is shorter than rows 605A and 606A (e.g., has fewer apertures). In some embodiments, the zigzag-edge rectangular aperture array 626A may have fewer alternating rows than the zigzag-edge rectangular aperture array 602A, wherein each alternating row is longer than rows 605A and 606A (e.g., has more apertures).

[0072] Figure 6B An example diagram is shown illustrating the number of beams that can be used to scan a wafer in a given FOV with different beam pitches in various aperture arrays. The horizontal axis represents the beam pitch in micrometers, decreasing from left to right. The vertical axis represents the number of beams that can be used to scan a wafer in a given FOV. Curve 608B represents the number of beams that can be used to scan a wafer in a given FOV in a hexagonal aperture array with varying beam pitches (e.g., Figure 5C The hexagonal aperture array 502C can be used to scan the number of beams of the wafer in a continuous scan mode. Curve 610B represents a rectangular aperture array with serrated edges (e.g., with varying beam pitch) that can be used. Figure 6A The number of beams used in a zigzag-edged rectangular array (602A) is to scan the wafer in a continuous scan mode. For example... Figure 6B As shown, the number of beams that can be used in any aperture array increases as the beam pitch decreases, because the number of beams that can be used in the aperture array increases as the distance between each aperture decreases. Since a serrated edge rectangular aperture array may not result in unused areas when operating the imaging system in continuous scan mode, it can achieve higher throughput and is superior to a hexagonal aperture array. For example, in continuous scan mode, a hexagonal aperture array with a beam pitch of 210 μm can allow 161 beams to scan the wafer in the FOV, while a serrated edge rectangular aperture array with a beam pitch of 210 μm can allow 217 beams to scan the wafer in the same FOV.

[0073] Figure 7 An example of an aperture array 700 is shown, which includes a first set of apertures forming a 2D hexagonal shape 702 (e.g., Figure 4B The hexagonal aperture array 402B and the second set of apertures forming a 2D serrated edge rectangular shape 704 (e.g., Figure 6AThe array of rectangular apertures 700 with serrated edges (602A) is described. The aperture array 700 may have a hexagonal shape with four sets of serrated corner apertures 704A. Each set of serrated corner apertures 704A may include at least two rows of apertures offset in a direction perpendicular to the direction in which these rows extend (e.g., horizontally, vertically). Each offset row may extend from an edge of the hexagonal shape at an angle greater than 90 degrees from the horizontal edge of the hexagonal shape.

[0074] In some embodiments, multi-beam systems (e.g., Figure 1 The EBI system 100 can operate in different scanning modes. For example, for high-resolution applications, the multi-beam system can operate in skip scan mode, while for high-current applications, the multi-beam system can operate in continuous scan mode. In some embodiments, a set of hexagonal apertures 702 (e.g., Figure 3B The aperture 330 or 332 can be controlled to operate in a pass-through state so that the primary electron beam (e.g., Figure 2 Electrons from the primary electron beam 202 are able to pass through a set of hexagonal apertures 702 during the skip scan mode. During the skip scan mode, a set of serrated-edge rectangular apertures 704 (e.g., serrated corner apertures 704A) that are not shared with the set of hexagonal apertures 702 (e.g., serrated corner apertures 704A) Figure 3B The aperture of aperture 334 can be controlled to operate in a blocking state to block electrons from the primary electron beam from passing through the non-shared aperture. For example, each aperture can be independently and individually controlled to be in a passing state, in which the deflection structure (e.g., Figure 3B The deflection structure 324 or 326 can guide the electron beam (e.g., Figure 3B The electron beam (336 or 338) directly enters the aperture, or is blocked. In the blocked state, the deflection structure (e.g., Figure 3B The deflection structure 328 can guide the electron beam (e.g., Figure 3B The electron beam 340 is blanked (e.g., deviated from the entry direction and strikes the wall of the orifice) and the electron beam can be prevented from passing through the orifice.

[0075] In some embodiments, a set of serrated-edge rectangular apertures 704 can be controlled to operate in a pass-through state, allowing electrons from the primary electron beam to pass through the set of serrated-edge rectangular apertures 704 during continuous scan mode. During continuous scan mode, the apertures of a set of hexagonal apertures 702 not shared with the set of serrated-edge rectangular apertures 704 can be controlled to operate in a blocking state, preventing electrons from the primary electron beam from passing through the non-shared apertures. In some embodiments, a darker area at the center of the aperture array 700 illustrates an aperture that can be controlled to always operate in a pass-through state, allowing electrons from the primary electron beam to pass through the apertures during both skip scan mode and continuous scan mode.

[0076] Although Figure 7 The apertures along the boundaries of the aperture array 700 are not explicitly shown, but it should be understood that the apertures exist on the boundaries to give the aperture array 700 its unique shape.

[0077] Figure 8 An example process 800 for inspecting a wafer is shown. This process may include an inspection system (e.g., Figure 1 The EBI system 100) allows the inspection system to use an aperture array (e.g., Figure 4B 402B hexagonal aperture array; Figure 6A 602A aperture array; Figure 7 Aperture array 700) scanning wafer (e.g., Figure 2 Sample 208). The aperture array may include a first set of apertures forming a 2D hexagonal shape (e.g., Figure 7 A set of orifices 702; Figure 4B The hexagonal aperture array 402B and the second set of apertures forming a 2D serrated edge rectangular shape (e.g., Figure 7 The orifice is 704; Figure 6A A rectangular aperture array 602A with serrated edges. The aperture array can have a hexagonal shape with four sets of serrated corner apertures (e.g., Figure 7 (704A) Serrated corner orifices. Each set of serrated corner orifices may include at least two rows of orifices offset in a direction (e.g., vertical) perpendicular to the direction in which these rows extend (e.g., horizontal). Each offset row may extend from the edge of a hexagonal shape at an angle greater than 90 degrees from the horizontal edge of the hexagonal shape.

[0078] In step 801, the inspection system can select a scanning mode for inspecting the wafer from a first scanning mode and a second scanning mode. In the first scanning mode, the first set of 2D apertures in the aperture array can be used to inspect the wafer. For example, the inspection system can use the first set of 2D apertures to operate in a skip scan mode for high-resolution applications and in a continuous scan mode for high-current applications. In some embodiments, a set of hexagonal apertures (e.g., Figure 3B The aperture 330 or 332 can be controlled to operate in a pass-through state so that the primary electron beam (e.g., Figure 2 Electrons from the primary electron beam 202 are able to pass through a set of hexagonal apertures during the skip scan mode. During the skip scan mode, a set of serrated-edge rectangular apertures (e.g., serrated corner apertures 704A) that are not shared with the set of hexagonal apertures (e.g., serrated corner apertures 704A) Figure 3B The aperture 334 can be controlled to operate in a blocking state to block electrons from the primary electron beam from passing through the non-shared aperture. For example, each aperture can be independently and individually controlled to be in a passing state, in which the deflection structure (e.g., Figure 3B The deflection structure 324 or 326 can guide the electron beam (e.g., Figure 3B The electron beam (336 or 338) directly enters the aperture, or is blocked. In the blocked state, the deflection structure (e.g., Figure 3B The deflection structure 328 can guide the electron beam (e.g., Figure 3B The electron beam 340 is blanked (e.g., deviated from the entry direction and hits the wall of the orifice) and the electron beam can be blocked from passing through the orifice.

[0079] In the second scanning mode, the second set of 2D apertures in the aperture array can be used to inspect the wafer. For example, a set of serrated-edge rectangular apertures can be controlled to operate in a pass-through state, allowing electrons from the primary electron beam to pass through the set of serrated-edge rectangular apertures during continuous scanning. During continuous scanning, apertures in a set of hexagonal apertures not shared with the set of serrated-edge rectangular apertures can be controlled to operate in a blocking state to block electrons from the primary electron beam from passing through the non-shared apertures. In some embodiments, the second set of 2D apertures may partially overlap with the first set of 2D apertures (e.g., Figure 7 (The darker area at the center of the aperture array 700). The overlapping apertures can be controlled to always operate in a pass-through state, so that electrons from the primary electron beam can pass through the apertures during both the skip scan mode and the continuous scan mode.

[0080] In step 803, the inspection system can configure the aperture array based on the selected scanning mode. For example, if a continuous scanning mode is selected, the aperture array can be rotated appropriately to maximize the scanning area corresponding to a set of rectangular apertures with serrated edges. On the other hand, if a skip scanning mode is selected, the aperture array may not need to be rotated. Furthermore, the passage and obstruction states of the aperture array can be adjusted accordingly.

[0081] The various aspects of this disclosure are set forth in the following numbered clauses:

[0082] 1. A microelectromechanical system (MEMS) structure, comprising:

[0083] The first set of two-dimensional (2D) apertures is configured for use in the first scanning mode; and

[0084] The second set of 2D apertures is configured to be used in a second scanning mode that is different from the first scanning mode;

[0085] The second group of 2D orifices partially overlaps with the first group of 2D orifices.

[0086] 2. The structure according to Clause 1, wherein the first set of 2D apertures comprises an array of apertures forming a rectangular shape with serrated edges.

[0087] 3. The structure according to Clause 1, wherein the first set of 2D apertures includes apertures not used in the second scanning mode, and the second set of 2D apertures includes apertures not used in the first scanning mode.

[0088] 4. The structure according to any one of clauses 1 to 3, wherein the first set of 2D apertures comprises:

[0089] First row of openings;

[0090] Second row of openings;

[0091] The third row of holes;

[0092] Fourth row of holes;

[0093] in:

[0094] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction;

[0095] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

[0096] 5. The structure according to Clause 3, wherein the offset includes non-overlapping apertures in the second direction.

[0097] 6. The structure according to any one of clauses 4 to 5, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

[0098] 7. The structure according to Clause 6, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

[0099] 8. The structure according to any one of clauses 1 to 7, wherein the second set of 2D apertures comprises an array of apertures forming a hexagonal shape.

[0100] 9. The structure according to any one of clauses 1 to 8, wherein the first scanning mode is a continuous scanning mode.

[0101] 10. The structure according to Clause 9, wherein the first set of 2D apertures is configured to be rotated when operating in the continuous scanning mode.

[0102] 11. The structure according to any one of clauses 1 to 10, wherein the second scanning mode is a skip scanning mode.

[0103] 12. A microelectromechanical system (MEMS) structure, comprising:

[0104] The first set of two-dimensional (2D) apertures includes an array of apertures forming a rectangular shape with serrated edges; and

[0105] The second set of 2D apertures includes an array of apertures forming a hexagonal shape;

[0106] The second group of 2D orifices partially overlaps with the first group of 2D orifices; and

[0107] The first set of 2D apertures is configured for use in a first scanning mode, and the second set of 2D apertures is configured for use in a second scanning mode different from the first scanning mode.

[0108] 13. The structure according to Clause 12, wherein the first set of 2D apertures includes apertures not used in the second scanning mode, and the second set of 2D apertures includes apertures not used in the first scanning mode.

[0109] 14. The structure according to any one of clauses 12 to 13, wherein the first set of 2D apertures comprises:

[0110] First row of openings;

[0111] Second row of openings;

[0112] The third row of holes;

[0113] Fourth row of holes;

[0114] in:

[0115] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction;

[0116] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

[0117] 15. The structure according to Clause 14, wherein the offset includes non-overlapping apertures in the second direction.

[0118] 16. The structure according to any one of clauses 14 to 15, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

[0119] 17. The structure according to Clause 16, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

[0120] 18. The structure according to any one of clauses 12 to 17, wherein the first scanning mode is a continuous scanning mode.

[0121] 19. The structure according to Clause 18, wherein the first set of 2D apertures is configured to be rotated when operating in the continuous scanning mode.

[0122] 20. The structure according to any one of clauses 12 to 19, wherein the second scanning mode is a skip scanning mode.

[0123] 21. A microelectromechanical system (MEMS) structure, comprising:

[0124] The array of orifices forms a hexagonal shape and has four sets of serrated corner orifices;

[0125] Each set of serrated corner openings includes:

[0126] Two rows of openings extending in a first direction, wherein the two rows of openings are offset in a second direction perpendicular to the first direction, wherein

[0127] Each row extends from the first edge of the hexagonal shape in the first direction, and wherein the first edge of the hexagonal shape extends upward at a third angle greater than 90 degrees from the second edge of the hexagonal shape extending in the first direction.

[0128] 22. The structure according to Clause 21, wherein the array includes a first set of 2D apertures forming a rectangular shape with serrated edges.

[0129] 23. The structure according to Clause 22, wherein the serrated edge rectangular shape includes at least some of the openings forming the hexagonal shape and the four sets of serrated corner openings.

[0130] 24. The structure according to any one of clauses 21 to 23, wherein the array includes a second set of 2D apertures forming the hexagonal shape.

[0131] 25. The structure according to any one of clauses 22 to 24, wherein the first set of 2D apertures includes apertures not used in the second scanning mode and the second set of 2D apertures includes apertures not used in the first scanning mode.

[0132] 26. The structure according to any one of clauses 21 to 25, wherein the offset includes non-overlapping apertures in the second direction.

[0133] 27. The structure according to any one of Clauses 25 to 26, wherein the first scanning mode is a continuous scanning mode.

[0134] 28. The structure according to any one of clauses 25 to 27, wherein the first set of 2D apertures is configured to be rotated when operating in the continuous scanning mode.

[0135] 29. The structure according to any one of clauses 25 to 28, wherein the second scanning mode is a skip scanning mode.

[0136] 30. A microelectromechanical system (MEMS) structure, comprising:

[0137] First row of openings;

[0138] The second row of orifices is located below the first row of orifices;

[0139] The third row of orifices is located below the second row of orifices; and

[0140] The fourth row of orifices is located below the third row of orifices;

[0141] in:

[0142] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction; and

[0143] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

[0144] 31. The structure according to Clause 30, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

[0145] 32. The structure according to Clause 31, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

[0146] 33. The structure according to any one of clauses 30 to 32, wherein the structure is configured for use in the continuous scanning mode of a multi-beam inspection system.

[0147] 34. The structure according to Clause 33, wherein the structure is configured to be rotated when operating in the continuous scan mode.

[0148] 35. A microelectromechanical system (MEMS) structure, comprising:

[0149] The first structure includes:

[0150] First row of openings;

[0151] Second row of openings;

[0152] The third row of holes;

[0153] Fourth row of holes;

[0154] in:

[0155] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction; and

[0156] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction;

[0157] The second structure includes an array of apertures forming a hexagonal shape; and

[0158] The first structure is superimposed on the second structure.

[0159] 36. The MEMS structure according to Clause 35, wherein the first row of apertures and the third row of apertures have a first length and the second row of apertures and the fourth row of apertures have a second length, and in the second direction, the first length is longer than the second length.

[0160] 37. The MEMS structure according to Clause 36, wherein the first row of apertures, the second row of apertures, the third row of apertures, and the fourth row of apertures alternate in the first direction.

[0161] 38. The MEMS structure according to any one of clauses 35 to 37, wherein the first structure is configured for use in a continuous scanning mode of a multi-beam inspection system.

[0162] 39. The MEMS structure according to Clause 38, wherein the first structure is configured to be rotated when operating in the continuous scan mode.

[0163] 40. The MEMS structure according to any one of clauses 35 to 39, wherein the second structure is configured for use in a skip scan mode of a multi-beam inspection system.

[0164] 41. A charged particle multi-beam system for generating multiple beams for inspecting a wafer positioned on a stage, the system comprising:

[0165] The first structure includes:

[0166] First row of openings;

[0167] Second row of openings;

[0168] The third row of holes;

[0169] Fourth row of holes;

[0170] in:

[0171] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction; and

[0172] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction;

[0173] The second structure includes an array of apertures forming a hexagonal shape; and

[0174] The controller includes circuitry configured to perform a continuous scan check using the first structure or a skip scan check using the second structure.

[0175] 42. The system according to Clause 41, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

[0176] 43. The system according to Clause 42, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

[0177] 44. The system according to any one of clauses 41 to 43, wherein the circuitry is further configured to rotate the first structure during the performance of the continuous scan inspection.

[0178] 45. A method for inspecting a wafer positioned on a stage, the method comprising:

[0179] Select the scan mode for inspecting the wafer from the first scan mode and the second scan mode, wherein:

[0180] In the first scanning mode, the first set of two-dimensional (2D) apertures in the aperture array is used to inspect the wafer, and

[0181] In the second scanning mode, the second set of 2D apertures in the aperture array is used to inspect the wafer, wherein the second set of 2D apertures partially overlaps with the first set of 2D apertures; and

[0182] Configure the aperture array based on the selected scanning mode.

[0183] 46. ​​The method according to Clause 45, wherein the first set of 2D apertures comprises an array of apertures forming a rectangular shape with serrated edges.

[0184] 47. The method according to Clause 45, wherein the first set of 2D apertures includes apertures not used in the second scanning mode, and the second set of 2D apertures includes apertures not used in the first scanning mode.

[0185] 48. The method according to any one of clauses 45 to 47, wherein the first set of 2D apertures comprises:

[0186] First row of openings;

[0187] Second row of openings;

[0188] The third row of holes;

[0189] Fourth row of holes;

[0190] in:

[0191] The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction;

[0192] The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

[0193] 49. The method according to Clause 47, wherein the offset includes non-overlapping orifices in the second direction.

[0194] 50. The method according to any one of clauses 48 to 49, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

[0195] 51. The method according to Clause 50, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

[0196] 52. The method according to any one of clauses 45 to 51, wherein the second set of 2D apertures comprises an array of apertures forming a hexagonal shape.

[0197] 53. The method according to any one of clauses 45 to 52, wherein the first scanning mode is a continuous scanning mode.

[0198] 54. The method according to Clause 53, wherein the first set of 2D apertures is configured to be rotated when operating in the continuous scanning mode.

[0199] 55. The method according to any one of clauses 45 to 54, wherein the second scanning mode is a skip scanning mode.

[0200] It should be noted that more exemplary embodiments of aperture arrays are possible and are not limited to the examples presented in this disclosure.

[0201] A non-transitory computer-readable medium may be provided, which stores information for a processor (e.g., Figures 1-2The processor of controller 109 executes the following instructions: selecting a mode, configuring the aperture array based on the selected mode, image processing, data processing, beam scanning, database management, graphic display, operation of charged particle beam devices or other imaging equipment, etc. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tape or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with an aperture pattern, RAM, PROM and EPROM, FLASH-EPROM or any other flash memory, NVRAM, cache, registers, any other memory chips or cassette memory, and network versions of the above.

[0202] It should be understood that the embodiments of this disclosure are not limited to the exact structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A microelectromechanical system (MEMS) structure, comprising: The first set of 2D apertures is configured for use in the first scanning mode; as well as The second set of 2D apertures is configured to be used in a second scanning mode that is different from the first scanning mode; The second group of 2D orifices partially overlaps with the first group of 2D orifices, and The first group of 2D apertures includes apertures not used in the second scanning mode, and the second group of 2D apertures includes apertures not used in the first scanning mode.

2. The structure according to claim 1, wherein the first set of 2D apertures comprises an array of apertures forming a rectangular shape with serrated edges.

3. The structure according to claim 1, wherein the first group of 2D apertures comprises: First row of openings; Second row of openings; The third row of holes; Fourth row of holes; in: The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction; The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

4. The structure according to claim 3, wherein the offset includes non-overlapping apertures in the second direction.

5. The structure according to claim 3, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

6. The structure according to claim 5, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

7. The structure according to claim 1, wherein the second set of 2D apertures comprises an array of apertures forming a hexagonal shape.

8. The structure according to claim 1, wherein the first scanning mode is a continuous scanning mode.

9. The structure according to claim 8, wherein the first set of 2D apertures is configured to be rotated when operating in the continuous scanning mode.

10. The structure according to claim 1, wherein the second scanning mode is a skip scanning mode.

11. A method for inspecting a wafer positioned on a stage, the method comprising: Select the scan mode for inspecting the wafer from the first scan mode and the second scan mode, wherein: In the first scanning mode, the first set of two-dimensional (2D) apertures in the aperture array is used to inspect the wafer, and In the second scanning mode, the second set of 2D apertures in the aperture array is used to inspect the wafer, wherein the second set of 2D apertures partially overlaps with the first set of 2D apertures; and Configure the aperture array based on the selected scanning mode. The first group of 2D apertures includes apertures not used in the second scanning mode, and the second group of 2D apertures includes apertures not used in the first scanning mode.

12. The method of claim 11, wherein the first set of 2D apertures comprises an array of apertures forming a rectangular shape with serrated edges.

13. The method of claim 11, wherein the first set of 2D apertures comprises: First row of openings; Second row of openings; The third row of holes; Fourth row of holes; in: The first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices are parallel to each other in a first direction; The first row of orifices and the third row of orifices are offset from the second row of orifices and the fourth row of orifices in a second direction perpendicular to the first direction.

14. The method of claim 13, wherein the offset comprises non-overlapping orifices in the second direction.

15. The method of claim 13, wherein the first row of orifices and the third row of orifices have a first length and the second row of orifices and the fourth row of orifices have a second length, and in the second direction, the first length is longer than the second length.

16. The method of claim 13, wherein the first row of orifices, the second row of orifices, the third row of orifices, and the fourth row of orifices alternate in the first direction.

17. The method of claim 11, wherein the second set of 2D apertures comprises an array of apertures forming a hexagonal shape.

18. The method of claim 11, wherein the first scanning mode is a continuous scanning mode.

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