Microelectromechanical system (MEMS) structure and non-transitory computer readable medium for inspecting a wafer positioned on a stage

Abstract

This invention discloses an apparatus, system, and method for optimizing the geometry of a beam array in a multi-beam detection tool. In some embodiments, a microelectromechanical system (MEMS) may include a first column of apertures; a second column of apertures positioned below the first column of apertures; a third column of apertures positioned below the second column of apertures; and a fourth column of apertures positioned below the third column of apertures; wherein the first, second, third, and fourth columns are parallel to each other in a first direction; the first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; the first and third columns have a first length; the second and fourth columns have a second length; and the first length is greater than the second length in the second direction.

Description

Technical Field

[0001] The description in this article pertains to the field of charged particle beam systems, and more specifically, to the optimization of beam array geometry for multi-beam detection systems. Prior Technology

[0002] In the manufacturing process of integrated circuits (ICs), unfinished 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 employed. SEMs transfer low-energy electrons (e.g., <1 keV) or high-energy electrons to a surface and use detectors to record secondary or backscattered electrons leaving the surface. By recording these electrons at different excitation locations on the surface, images can be generated with nanometer-level spatial resolution.

[0003] SEMs can be single-beam or multi-beam systems. Single-beam SEMs use a single electron beam to scan the surface, while multi-beam SEMs use multiple electron beams to scan the surface simultaneously. Multi-beam systems can achieve higher imaging throughput compared to single-beam systems. However, due to their lack of structural flexibility, multi-beam systems also have more complex structures. Optimizing the imaging throughput of a multi-beam system can be difficult due to its higher complexity. Summary of the Invention

[0004] Embodiments of the present invention provide apparatus, systems, and methods for beam array geometry optimization of multi-beam detection tools. In some embodiments, a microelectromechanical system (MEMS) may include: a first column of apertures; a second column of apertures; a third column of apertures; and a fourth column of apertures; wherein the first, second, third, and fourth columns are parallel to each other in a first direction; the first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; the first and third columns have a first length; the second and fourth columns have a second length; and the first length is greater than the second length in the second direction.

[0005] In some embodiments, the MEMS structure may include: a first structure comprising: a first column of apertures; a second column of apertures positioned below the first column of apertures; a third column of apertures positioned below the second column of apertures; and a fourth column of apertures positioned below the third column of apertures; wherein the first, second, third, and fourth columns are parallel to each other in a first direction; the first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; the first and third columns have a first length; the second and fourth columns have a second length; and the first length is greater than the second length in the second direction; a second structure comprising an array of apertures forming a hexagonal shape; and wherein the first structure is superimposed on the second structure.

[0006] In some embodiments, a charged particle multi-beam system for generating a plurality of beams for detecting a wafer positioned on a stage may include a first structure and a second structure. The first structure may include: a first column of apertures; a second column of apertures; a third column of apertures; and a fourth column of apertures; wherein the first, second, third, and fourth columns are parallel to each other in a first direction; the first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; the first and third columns have a first length; the second and fourth columns have a second length; and the first length is greater than the second length in the second direction. The second structure may include an array of apertures forming a hexagonal shape. The system may further include a controller comprising circuitry configured to perform continuous scan detection using the first structure or skip scan detection using the second structure. Simple Explanation of the Diagram

[0007] Figure 1 is a schematic diagram illustrating an exemplary electron beam detection (EBI) system conforming to an embodiment of the present invention.

[0008] Figure 2 is a schematic diagram illustrating a portion of the exemplary charged particle beam detection system of Figure 1, which conforms to an embodiment of the present invention.

[0009] Figure 3A is a graphical illustration of the generation of a fine beam in a multi-beam system according to an embodiment of the present invention.

[0010] Figure 3B is a graphical illustration of a MEMS aperture array conforming to an embodiment of the present invention.

[0011] Figures 4A and 4B are graphical illustrations of example aperture arrays used to generate fine beams.

[0012] Figure 4C is an example curve showing the number of fine beams in different aperture arrays of a wafer in a given FOV that can be used to scan the number of fine beams in a given FOV at different fine beam spacings.

[0013] Figures 5A to 5C are graphical illustrations of example aperture arrays used to generate fine beams.

[0014] Figure 5D is an example curve showing the fill factor in different aperture arrays of a wafer in a given FOV that can be used to scan the wafer at different fine beam spacings.

[0015] Figure 6A is a graphical illustration of an example aperture array for generating a fine beam, conforming to an embodiment of the present invention.

[0016] Figure 6B is an example graph of the number of fine beams in different aperture arrays of a wafer in a given FOV that can be used to scan at different fine beam spacings according to an embodiment of the present invention.

[0017] Figure 7 is a graphical illustration of an example aperture array for generating a fine beam according to an embodiment of the present invention.

[0018] Figure 8 illustrates an example program for inspecting a wafer according to an embodiment of the present invention. Implementation

[0019] Detailed reference will now be made to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, wherein, unless otherwise indicated, the same numbers in different figures denote the same or similar elements. The embodiments set forth in the following description of the exemplary embodiments do not represent all embodiments conforming to the invention. In fact, they are merely examples of apparatuses and methods conforming to the nature of the subject matter recounted in the appended claims. For example, although some embodiments are described in the context of utilizing electron beams, the invention is not limited thereto. Other types of charged particle beams can be similarly applied. Furthermore, other imaging systems, such as optical imaging, photodetection, X-ray detection, or the like, can be used.

[0020] Electronic devices consist of circuits formed on a silicon wafer called a substrate. Many circuits can be formed together on the same silicon wafer and are called integrated circuits or ICs. The size of these circuits has been significantly reduced so that more of them can be mounted on the substrate. For example, the IC chip in a smartphone can be as small as a thumbnail and can still include more than 2 billion transistors, each smaller than 1 / 1000th the size of a human hair.

[0021] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process that often involves hundreds of individual steps. Even an error in a single step can lead to a defect in the finished 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, that is, to improve the overall yield of the process.

[0022] One component of yield improvement is monitoring the wafer fabrication process to ensure that a sufficient number of functional integrated circuits are being produced. One method of monitoring is to inspect the wafer circuit structure at various stages of its formation. This can be done using a scanning electron microscope (SEM). SEM can be used to virtually image these extremely small structures, thus obtaining an "image" of the wafer's structure. The image can be used to determine whether the structure has been properly formed and whether it is in the correct location. If the structure is defective, the process can be adjusted to make the defect less likely to reappear.

[0023] The working principle of a surface-mount imager (SEM) is similar to that of a camera. A camera captures images by receiving and recording the brightness and color of light reflected or emitted from a person or object. Similarly, an SEM captures "images" by receiving and recording the energy or quantity of electrons reflected or emitted from a structure. Before capturing such "images," an "electron beam" is supplied to the structure, and as electrons are reflected or emitted from the structure, the SEM's detector receives and records the energy or quantity of these electrons to produce an image. To capture these "images," some SEMs use a single electron beam (called a "single-beam SEM"), while others use multiple electron beams (called a "multi-beam SEM") to capture multiple "images" of the wafer. By using multiple electron beams, the SEM can supply more electron beams to the structure to obtain these multiple "images," resulting in more electrons being emitted from the structure. Therefore, the detector can simultaneously receive more emitted electrons and produce images of the wafer structure with higher efficiency and faster speed.

[0024] In multiple charged particle beam imaging systems (e.g., multi-beam SEM), an aperture array can be used to form multiple fine beams. The aperture array may include multiple through-holes ("apertures") that can split a single charged particle beam into multiple fine beams. The number of apertures in the aperture array can affect the throughput of the multiple charged particle beam imaging system. Throughput indicates how quickly the imaging system can complete an inspection task per unit time. During the inspection procedure, the imaging system can generate an image from the surface of a scanned sample. For defect detection, the image can be generated by each fine beam. Because more fine 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 result in a higher throughput for the imaging system.

[0025] The geometry of an aperture array can affect the output of multiple charged particle beam imaging systems. However, multiple charged particle beam imaging systems are typically designed for specific applications requiring specific scan modes. The geometry of the aperture array that optimizes the output of the imaging system in one scan mode may not optimize the output of the imaging system in another scan mode. To accommodate different applications, multiple 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 capabilities to optimize the output of the imaging system for a specific scan mode.

[0026] Furthermore, some embodiments of the present invention provide methods and systems for optimizing the geometry of a beam array in a multi-beam detection 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 configured in a first two-dimensional (2D) shape and the second set of apertures is configured in a second 2D shape. The multi-beam detection system may project a charged particle beam onto different sets of apertures. The multi-beam detection system may control the first and second sets of apertures to operate in different pass-through or blockage states (or "modes"), and others. In the "pass-through" state, the apertures may allow the electron beam to pass through. In the "blockage" state, the apertures may block the electron beam. In other states, the apertures may focus or bend the electron beam, and others. When the multi-beam detection system projects a charged particle beam onto the first and second sets of apertures, the first and second sets of apertures may operate in either the 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 of the different geometries of the first and second sets of apertures, multi-beam detection systems can have multiple operating modes and are suitable for multiple applications that optimize the output of the detection system.

[0027] For clarity, the relative dimensions of the components in the 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 only differences with respect to individual embodiments are described.

[0028] As used herein, unless otherwise specifically stated, the term "or" covers all possible combinations, unless impractical. For example, if a statement indicates that components may include A or B, then unless otherwise specifically stated or impractical, the components may include A, or B, or A and B. As a second example, if a statement indicates that components may include A, B, or C, then unless otherwise specifically stated or impractical, the components may include A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C.

[0029] Figure 1 illustrates an exemplary electron beam inspection (EBI) system 100 conforming to an embodiment of the present invention. The EBI system 100 can be used for imaging. As shown in Figure 1, 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 positioned 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 additional loading ports. The first loading port 106a and the second loading port 106b receive wafer front-opening unit cassettes (FOUPs) containing wafers to be inspected (e.g., semiconductor wafers or wafers made of other materials) or samples (wafers and samples are interchangeable). A "batch" is a plurality of wafers that can be loaded for processing as a batch.

[0030] 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 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 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.

[0031] The controller 109 is electronically connected to the electron beam tool 104. The controller 109 may be a computer configured to perform various controls on the EBI system 100. Although the controller 109 is shown in FIG1 as being external to the structure including the main chamber 101, the loading / locking chamber 102 and the EFEM 106, it should be understood that the controller 109 may be part of the structure.

[0032] In some embodiments, controller 109 may include one or more processors (not shown). A processor may be a general-purpose or specialized electronic device capable of manipulating or processing information. For example, a processor may include any number of central processing units (or "CPUs"), graphics processing units (or "GPUs"), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general-purpose array logic (GALs), composite 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 circuit capable of data processing. A processor may also be a virtual processor, comprising one or more processors distributed across multiple machines or devices coupled via a network.

[0033] In some embodiments, controller 109 may further include one or more memories (not shown). The memory may be a general-purpose or specific electronic device capable of storing program code and data accessible by a processor (e.g., via a bus). For example, the memory may include any number of random access memory (RAM), read-only memory (ROM), optical discs, magnetic disks, hard disk drives, solid-state drives, flash drives, secure digital cards (SD cards), memory sticks, compact flash (CF) cards, or any combination of any type of storage device. The program 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, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0034] Referring now to FIG2, it is a schematic diagram illustrating an exemplary electron beam tool 104 comprising a portion of the EBI system 100 of FIG1, conforming to an embodiment of the present invention. 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 aperture plate") 271, a condenser lens 210, a source conversion unit 220, a primary 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 further include a secondary projection system 250 and an electron detection device 240. The primary projection system 230 may include an objective lens 231. The electron detection device 240 may include a plurality of detection elements 241, 242, and 243. The beam splitter 233 and the deflection scanning unit 232 can be located inside the primary projection system 230.

[0035] The electronic source 201, coulomb aperture plate 271, condenser lens 210, source conversion unit 220, beam splitter 233, deflection scanning unit 232, and primary projection system 230 can be aligned with the main optical axis 204 of device 104. The secondary projection system 250 and electronic detection device 240 can be aligned with the secondary optical axis 251 of device 104.

[0036] 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 extract or accelerate the primary electrons by the extractor and / or anode to form a primary electron beam 202, which forms a primary beam crossover (virtual or real) 203. The primary electron beam 202 can be visualized as being emitted from the primary beam crossover 203.

[0037] Source conversion unit 220 may include an image forming element array (not shown), an aberration compensator array (not shown), a beam confinement aperture array (not shown), and a pre-bent micro-deflector array (not shown). In some embodiments, the pre-bent micro-deflector array deflects a plurality of primary fine beams 211, 212, 213 of the primary electron beam 202 to enter perpendicularly into the beam confinement aperture array, the image forming element array, and the aberration compensator array. In some embodiments, a condenser lens 210 is designed to focus the primary electron beam 202 into parallel beams and incident perpendicularly onto source conversion unit 220. The image forming element array may include a plurality of micro-deflectors or microlenses to influence the plurality of primary fine beams 211, 212, 213 of the primary electron beam 202 and form a plurality of parallel images (virtual or real) of the primary beam crossing 203, one image relating to each of the primary fine beams 211, 212, and 213. 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 a plurality of microlenses to compensate for field curvature aberrations of the primary fine beams 211, 212, and 213. The astigmatism compensator array may include a plurality of micro-astigmatism correctors to compensate for astigmatic aberrations of the primary fine beams 211, 212, and 213. The beam limiting aperture array may be configured to limit the diameter of the individual primary fine beams 211, 212, and 213. Figure 2 shows three primary fine beams 211, 212, and 213 as an example, and it should be understood that the source conversion unit 220 may be configured to form any number of primary fine beams. The controller 109 may be connected to various components of the EBI system 100 of Figure 1, such as the source conversion unit 220, the electronic detection device 240, the primary projection system 230, or the motorized stage 209. In some embodiments, as will be explained in further detail below, the controller 109 may perform various image and signal processing functions. The controller 109 may also generate various control signals to manage the operation of the charged particle beam detection system.

[0038] Condenser lens 210 is configured to focus primary electron beam 202. Condenser lens 210 can be further configured to adjust the current of primary fine beams 211, 212, and 213 downstream of source conversion unit 220 by changing the focusing magnification of condenser lens 210. Alternatively, the current can be changed by altering the radial size of the beam limiting aperture corresponding to the individual primary fine beams within the beam limiting aperture array. The current can be changed by altering both the radial size of the beam limiting aperture and the focusing magnification of condenser lens 210. Condenser lens 210 can be an adjustable condenser lens that can be configured to have a movable position of its first principal plane. The adjustable condenser lens can be configured to be magnetic, which can cause off-axis fine beams 212 and 213 to illuminate source conversion unit 220 with a rotation angle. The rotation angle changes with the focusing magnification of the adjustable condenser lens or the position of the first principal plane. The condenser lens 210 may be an anti-rotation condenser lens, which can be configured to maintain a constant rotation angle when the focusing magnification of the condenser lens 210 is changed. In some embodiments, the condenser lens 210 may be an adjustable anti-rotation condenser lens, wherein the rotation angle does not change when the focusing magnification of the condenser lens 210 and the position of the first principal plane change.

[0039] Objective lens 231 can be configured to focus fine beams 211, 212, and 213 onto sample 208 for detection, and in the current embodiment, three detector spots 221, 222, and 223 are formed on the surface of sample 208. Coulomb aperture plate 271 is configured during operation to block peripheral electrons of the primary electron beam 202 to reduce the Coulomb effect. The Coulomb effect amplifies the size of each of the detector spots 221, 222, and 223 of the primary fine beams 211, 212, and 213, and thus degrades the detection resolution.

[0040] The beam splitter 233 can be, for example, a Wien filter, which includes electrostatic deflectors that generate electrostatic dipole fields and magnetic dipole fields (not shown in Figure 2). In operation, the beam splitter 233 can be configured to apply electrostatic forces to individual electrons of the primary fine beams 211, 212, and 213 by the electrostatic dipole fields. The electrostatic forces are equal in magnitude but opposite in direction to the magnetic forces applied to individual electrons by the magnetic dipole fields of the beam splitter 233. The primary fine beams 211, 212, and 213 can therefore pass through the beam splitter 233 at least substantially straight with at least substantially zero deflection angle.

[0041] In operation, the deflection scanning unit 232 is configured to deflect primary fine beams 211, 212, and 213 so that probe spots 221, 222, and 223 scan individual scanning areas across segments of the surface of sample 208. In response to the primary fine beams 211, 212, and 213 or probe spots 221, 222, and 223 incident on sample 208, electrons emerge from sample 208, generating three secondary electron beams 261, 262, and 263. Each of the secondary electron beams 261, 262, and 263 typically contains secondary electrons (with electron energies ≤ 50 eV) and backscattered electrons (with electron energies between 50 eV and the landing energies of the primary fine beams 211, 212, and 213). The beam splitter 233 is configured to deflect the secondary electron beams 261, 262, and 263 toward the secondary projection system 250. The secondary projection system 250 then focuses the secondary electron beams 261, 262, and 263 onto the detection elements 241, 242, and 243 of the electronic detection device 240. The detection elements 241, 242, and 243 are configured 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 scanned area of ​​sample 208.

[0042] In some embodiments, detection elements 241, 242, and 243 respectively detect corresponding secondary electron beams 261, 262, and 263, 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 the signals generated by all pixels within the detection element.

[0043] In some embodiments, controller 109 may include an image processing system comprising an image acquirer (not shown) and storage (not shown). The image acquirer may include one or more processors. For example, the image acquirer may include a computer, server, mainframe computer, terminal, personal computer, any kind of mobile computing device and the like, or combinations thereof. The image acquirer may be coupled to the electronic detection device 240 of device 104 via media communication such as: electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, the Internet, wireless networks, radio, and others, or combinations thereof. In some embodiments, the image acquirer may receive signals from the electronic detection device 240 and may construct images. 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, overlay indicators, and the like on the acquired image. The image acquirer may be configured to perform adjustments such as brightness and contrast of the acquired image. In some embodiments, the storage device may be a storage medium such as a hard disk, flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, and the like. The storage device may be coupled to an image acquisition device and may be used to save scanned raw image data as raw images and post-processed images.

[0044] In some embodiments, the image acquirer may acquire one or more images of a sample based on an imaging signal received from the electronic detection device 240. The imaging signal may correspond to a scanning operation for imaging charged particles. The acquired image may be a single image comprising a plurality of imaging regions. The single image may be stored in a memory. The single image may be an original image that can be divided into a plurality of regions. Each of these regions may contain an imaging region containing features of sample 208. The acquired image may comprise multiple images of a single imaging region of sample 208 sampled multiple times in a time sequence. The multiple images may be stored in a memory. In some embodiments, the controller 109 may be configured to perform image processing steps using multiple images of the same location of sample 208.

[0045] In some embodiments, controller 109 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain 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 fine beams 211, 212, and 213 incident on the wafer surface, can be used to reconstruct an image of the wafer structure under test. The reconstructed image can be used to reveal various features of the internal or external structure of sample 208, and thereby to reveal any defects that may exist in the wafer.

[0046] In some embodiments, the controller 109 may control the motorized stage 209 to move the sample 208 during the detection of the sample 208. In some embodiments, the controller 109 may enable the motorized stage 209 to continuously move the sample 208 in one direction at a constant speed. 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 procedure.

[0047] Although Figure 2 shows that device 104 uses three primary electron beams, it should be understood that device 104 may use two or more primary electron beams. The present invention does not limit the number of primary electron beams used in device 104.

[0048] Compared to single-beam charged particle imaging systems ("single-beam systems"), multi-beam charged particle imaging systems ("multi-beam systems") can be designed to optimize the output of different scanning modes. Embodiments of the present invention provide a multi-beam system capable of optimizing the output of different scanning modes by using beam arrays with different geometries suitable for different output and resolution requirements.

[0049] In some embodiments of the invention, an apparatus (e.g., a component of source conversion unit 220) can be used to generate an array of fine beams in different 2D geometric configurations for a multi-beam detection system. The apparatus may include at least one set of apertures in an aperture array, wherein each set of apertures includes different 2D geometric configurations 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 ideal set of apertures in the aperture array can be selected, and an ideal yield result (e.g., maximum yield) can be obtained for each application. Figure 3A illustrates fine beam generation in a multi-beam system including such an apparatus. In the example embodiment shown in Figure 3A, the multi-beam system can select a set of apertures for generating fine beams and thus has the ability to optimize different scanning modes, including increasing the output of different scanning modes.

[0050] Figure 3A is a graphical illustration of the generation of a fine beam in a multi-beam system according to an embodiment of the present invention. For example, a first operating mode may be a scanning mode using a first set of apertures, and a second operating mode may be a scanning mode using a second set of apertures. In Figure 3A, an electron source 201 emits electrons. A Coulomb aperture plate 271 blocks peripheral electrons 302 of the primary electron beam 202 to reduce the Coulomb effect. A condenser lens 210 focuses the primary electron beam 202 into a parallel beam incident on the source conversion unit 220 in the normal direction. The condenser lens 210 may be an adjustable condenser lens, as described in the section associated with Figure 2. In Figure 3A, the first principal plane of the adjustable condenser lens 210 can be adjusted to be closer to the electron source 201, wherein the projection area of ​​the primary electron beam 202 can be reduced. That is, the focusing magnification of the condenser lens 210 is enhanced in Figure 3A.

[0051] Source conversion unit 220 may include an aperture array. The aperture array may include apertures 304, 306, and 308. Because the condenser lens 210 reduces the projection area of ​​the primary electron beam 202, the primary electron beam 202 may only be incident on a portion of the apertures of the aperture array. For example, in FIG3A, only apertures 304, 306, and 308 are projected by the primary electron beam 202. The apertures or associated components of the aperture array may be controlled to operate in different pass-through or blockage states, such that electrons from the primary electron beam 202 can pass through a selected aperture or prevent electrons from the primary electron beam 202 from passing through a selected aperture. The apertures and associated components in the pass-through state allow the beam to pass through the aperture, and the apertures or associated components in the blockage state prevent the beam from passing through the aperture. For example, the aperture array may include a first set of apertures having a first combination of apertures in the pass-through or blockage states and a second set of apertures having a second combination of apertures in the pass-through or blockage states.

[0052] In some embodiments, the aperture array may be a microelectromechanical system (MEMS) aperture array, or the associated component may be a MEMS, which may be a portion of a MEMS array such as a MEMS aperture array. Each aperture of the MEMS aperture array may include a deflection structure (e.g., an electromagnetic coil, a circuit board, or any electromagnetic beam deflection device) and a truncated aperture downstream of the deflection structure.

[0053] Figure 3B is a graphical illustration of a MEMS aperture array 350 conforming to an embodiment of the present invention. The aperture array 350 may include multiple deflection structures corresponding to truncated apertures 330, 332, and 334, including deflection structures 324, 326, and 328. As shown in Figure 3B, each truncated aperture may have a hole aligned with the center of the opening of the corresponding deflection structure. The hole of the truncated aperture may be smaller than the opening of the deflection structure. The apertures of the aperture array 350 may be independently and individually controlled to be in a through-pass or blocked state. For example, the truncated aperture 330 is controlled to be in a through-pass state, wherein the electron beam 336 entering the deflection structure 324 is guided straight through, and the electron beam 336 may exit the truncated aperture 330. Similarly, the cutoff aperture 332 is controlled to be in a through state, wherein the deflection structure 326 guides the electron beam 338 entering the deflection structure 326 straight through, and the electron beam 338 can exit the cutoff aperture 332. In another example, the cutoff aperture 334 is controlled to be in a blocking state, wherein the deflection structure 328 guides the electron beam 340 through a blanket (e.g., deflected away from the entry direction and hitting the wall of the cutoff aperture 334), and the electron beam 340 can be blocked without passing through the aperture 334. The cutoff aperture can be controlled to be in a blocking state based on the 2D shape of the set of apertures associated with the scanning mode. In some embodiments, the deflection structure can be part of one or more components separate from the aperture array.

[0054] It should be noted that the number of fine beams generated in Figure 3A is determined by the exit angle of the primary electron beam 202 and the through-state or blocking state of the aperture projected by the primary electron beam 202. 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 are operating in the through-state, the number of fine beams generated is 3. If only a portion of apertures 304, 306, and 308 are operating in the through-state (e.g., only aperture 304 is operating in the through-state), the number of fine beams generated is less than 3 (e.g., 1). However, the upper limit of the number of fine beams generated can be limited by the exit angle of the primary electron beam 202. For example, as shown in Figure 3A, if the primary electron beam 202 only covers the apertures 304, 306 and 308 at its maximum emission angle, the maximum number of fine beams produced can be 3.

[0055] As illustrated in Figures 3A and 3B of the example embodiments, by controlling the pass-through or blockage state of a set of apertures with different 2D shapes, the multi-beam system can switch between different operating modes to meet the varying output 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 significant costs.

[0056] As shown in Figure 3A, the source conversion unit 220 may include a focusing, guiding, or deflecting component that enables the fine beams 314, 316, and 318 to converge and cross the common region downstream of the source conversion unit 220. It should be noted that Figures 3A to 3B are merely illustrative diagrams for explaining the principles and describing exemplary embodiments of the invention, and actual devices and systems may include more, fewer, or exactly the same components as shown, or configurations and arrangements of components in the same or different ways.

[0057] This invention proposes an apparatus and method for optimizing the geometry of a beam array in a multi-beam system. In some embodiments, the apparatus may be implemented as part of a source conversion unit 220 or one or more components associated with the source conversion unit 220. For example, the source conversion unit 220 may include one or more sets of apertures of an aperture array to be used in different scanning modes (e.g., skip scan mode, continuous scan mode) in a multi-beam system. A first set of apertures allows a first set of fine beams in a first geometry to scan a wafer, and a second set of apertures allows a second set of fine beams in a second geometry to scan a wafer. In some embodiments, the sets of apertures may be superimposed on each other and configured to operate in the same pass-through or blockage state or different pass-through or blockage states. An aperture in a pass-through state allows a beam to pass through the aperture, and an aperture in a blockage state prevents a beam from passing through the aperture. In some embodiments, the pass-through or blockage state of the aperture may be independently controlled by the circuitry of the source conversion unit 220. In some embodiments, the aperture array may be a microelectromechanical system (MEMS) aperture array. In some embodiments, the circuit may be a processor (e.g., the processor of controller 109 in FIG. 1), a memory storing executable instructions (e.g., the memory of controller 109 in FIG. 1), or a combination thereof. Controlling the pass-through or block-through state of the set of apertures in different modes ensures that only apertures with a selected beam array geometry are available for the corresponding scanning mode, and apertures with non-selected beam array geometries are unusable, thereby preventing errors in controlling the shape of the fine beam. It should be noted that a multi-beam system can operate in any number of any modes.

[0058] Correspondingly, 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, the different groups of apertures in the aperture array can thus be configured to operate in different pass-through or blockage states. In some embodiments, the pass-through or blockage states of the different groups of apertures can be independently controlled by the circuitry of the source conversion unit 220.

[0059] The size, orientation, and configuration of the aperture groups in the aperture array of the device can be any configuration, as long as the primary charged particle beam can be controlled to be substantially projected into one group in each operating mode of the multi-beam system. Figures 4A to 4B, 6A, and 7 are graphical illustrations of example aperture arrays for generating fine beams according to embodiments of the present invention. The aperture array can be used in the source conversion unit 220 in Figures 2 and 3A to 3B. In some embodiments, the aperture arrays shown in Figures 4A to 4B, 6A, and 7 can be MEMS aperture arrays.

[0060] Image acquisition using a multi-beam tool may involve generating a plurality of detection beams by an electron beam tool (e.g., electron beam tool 104 of Figures 1 and 2) and scanning a pattern (e.g., a grating pattern) over a wafer to be inspected (e.g., sample 208 of Figure 2). The image acquirer can be configured to acquire an image of a first imaging region by scanning the detection beams on the surface of the wafer in a first region and by receiving signals output from a detection self-detector (e.g., detection device 240 of Figure 2). The range of the beam scan may be limited by the field of view (FOV) of the electron beam tool, and therefore, the first imaging region may coincide with the FOV. To image another region, the wafer is moved by a sample stage (e.g., a motorized stage 209 of Figure 2) and the beam scans over the new region of the wafer. In skip scan mode, imaging can be performed at a specific area within the FOV, and when complete, the stage is moved and the procedure is repeated.

[0061] In continuous scanning mode, imaging is performed continuously while the wafer is carried by a movable stage along the x and y directions. For example, the stage can move in continuous linear motion under a charged particle beam column. Simultaneously, one or more charged particle beams (e.g., primary fine beams 211, 212, or 213 of FIG. 2) generated by a charged particle source (e.g., electron source 201 in FIG. 2) can scan back and forth linearly along scan lines in a pattern such as a grating pattern. Thus, one or more charged particle beams move to cover the moving wafer in discrete stripe segments. More information about continuous scanning using multi-beam devices can be found in U.S. Patent Application No. 62 / 850,461, which is incorporated herein by reference in its entirety.

[0062] Figure 4A illustrates an example aperture array 402A (hereinafter referred to as a square aperture array) that can be used in source conversion unit 220, comprising a set of apertures 404A in a square pattern. The points depicted in the shaded and unshaded areas represent the total number of possible fine beams that can scan a specific region of the wafer within the FOV at a given spacing (center-to-center distance of the fine beams or apertures). The fill factor of the fine beams used for the aperture array can be determined by calculating the fraction of the total number of possible fine beams for a region of the wafer within the FOV that can be scanned under the aperture array. For example, the fill factor can be the fraction of the total number of points in the FOV that are points in the shaded square region. In a multi-beam system operating in skip scan mode (e.g., EBI system 100 of Figure 1), the fill factor of the fine beams using the square aperture array 402A can be 64%.

[0063] Figure 4B illustrates an example aperture array 402B (hereinafter referred to as the hexagonal aperture array) with a set of apertures 404B in a hexagonal pattern that can be used in source conversion unit 220. Similar to Figure 4A, the points depicted in the shaded and unshaded areas represent the total number of possible fine beams that can scan a specific area of ​​the wafer within the FOV at a given spacing. The fill factor can be the fraction of the total number of points in the FOV that are in the shaded hexagonal areas. In a multi-beam system operating in skip scan mode (e.g., the EBI system 100 of Figure 1), the fine beam fill factor using the hexagonal aperture array 402B can be 83%.

[0064] Figure 4C shows an example graph illustrating the number of fine beams that can be used to scan a wafer in a given FOV in different aperture arrays at different fine beam spacings. The horizontal axis shows the fine beam spacing, decreasing in value from left to right in micrometers (μm). The vertical axis shows the number of fine beams that can be used to scan a wafer in a given FOV. Curve 408C represents the number of fine beams that can be used to scan a wafer in skip scan mode with a square aperture array (e.g., square aperture array 402A in Figure 4A) having varying fine beam spacing. Curve 410C represents the number of fine beams that can be used to scan a wafer in skip scan mode with a hexagonal aperture array (e.g., hexagonal aperture array 402B in Figure 4B) having varying fine beam spacing. As shown in Figure 4C, since the number of fine beams that can be used in the aperture array increases as the distance between each aperture decreases, the number of fine beams that can be used in any aperture array increases as the fine beam spacing decreases.

[0065] In some embodiments, a multi-beam system can scan a portion of a wafer using a hexagonal aperture array 402B and skip scan another adjacent portion of the wafer (e.g., by using a honeycomb pattern for scanning the wafer). For example, a square aperture array with a fine beam pitch of 210 μm can allow 169 fine beams to scan a wafer in the FOV using a skip scan mode, while a hexagonal aperture array with a fine beam pitch of 210 μm can allow 217 fine beams to scan a wafer in the same FOV using the same skip scan mode. Therefore, the hexagonal aperture array 402B may be more desirable than the square aperture array 402A in a multi-beam system using a skip scan mode due to the higher imaging throughput of the aperture array 402B.

[0066] Figures 5A, 5B, and 5C illustrate exemplary rotated hexagonal aperture arrays 502A, 502B, and 502C, respectively, which can be used in source conversion unit 220. Figure 5D shows example curves illustrating the fill factor in different aperture arrays that can be used to scan a wafer in a given FOV at different fine beam spacings. The hexagonal aperture arrays 502A, 502B, and 502C comprise a set of apertures 504A, 504B, and 504C, respectively, with reduced fine beam spacing, in that order. For example, hexagonal aperture array 502A may have three fine beams along each edge of the aperture array, hexagonal aperture array 502B may have six fine beams along each edge of the aperture array, and hexagonal aperture array 502C may have nine fine beams along each edge of the aperture array. While hexagonal aperture arrays increase the throughput of imaging systems compared to square aperture arrays, they are not necessarily better suited for continuous scanning modes, especially in skip scan modes. Due to the shape of hexagonal aperture arrays 502A, 502B, and 502C, their use in multi-beam systems operating in continuous scan modes results in areas 506A, 506B, and 506C where the scanning of beams in regions 506A, 506B, and 506C overlaps with previous scans performed by the utilized beams. This leads to areas 506A, 506B, and 506C being "unutilized" areas within the field of view (FOV). Furthermore, as the beam spacing decreases from hexagonal aperture array 502A to hexagonal aperture array 502C, the fill factor decreases in continuous scanning mode due to unused areas (e.g., 74% to 65% to 61%), as represented by curve 510 in Figure 5D. Curve 508 represents the fill factor of the square aperture array at different beam spacings in continuous scanning mode. As shown in Figure 5D, due to the increased number of beams per edge, the square aperture array may be more suitable than the hexagonal aperture array for increasing imaging output (e.g., increasing the number of beams used to scan the wafer) when operating the imaging system in continuous scanning mode. However, the square aperture array may not maximize imaging output in continuous scanning mode.

[0067] Figure 6A illustrates an example aperture array 602A (hereinafter referred to as a serrated-edge rectangular aperture array) that can be used in the source conversion unit 220, comprising a set of apertures 604A with a rectangular pattern of serrated edges. For example, the serrated-edge rectangular aperture array 602A may include a first column of apertures 605A and a second column of apertures 606A below the first column of 605A. In some embodiments, the first column of 605A may be longer than the second column of 606A (e.g., having more apertures), while in some other embodiments, the first column of 605A and 606A may have the same length but may be offset from each other. As shown in Figure 6A, the first column of 605A and the second column of 606A may be offset from each other in the horizontal direction, thereby giving the aperture array 602A its serrated-edge rectangular shape. The serrated edge rectangular aperture array 602A may include a plurality of first columns 605A and a plurality of second columns 606A, wherein the first columns 605A and the second columns 606A alternate in a direction (e.g., vertical) perpendicular to the direction in which the columns 605A and 606A extend (e.g., horizontally).

[0068] One advantage of using the serrated-edge rectangular aperture array 602 is the minimization of unused areas when used in continuous scanning mode. For example, in the embodiment shown in FIG. 6A, when the serrated-edge rectangular aperture array 602 is rotated in a specific manner, there may be no unused areas. Therefore, when used in continuous scanning 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 areas of the array 502C. That is, when operating in continuous scanning mode, using the serrated-edge rectangular aperture array 602A can result in a higher output of the imaging system (e.g., a fill factor of 81%).

[0069] In some embodiments, the shape of the zigzag-edge rectangular aperture array 624A can be modified by adding or reducing columns. For example, the zigzag-edge rectangular aperture array 624A may have more alternating columns than the zigzag-edge rectangular aperture array 602A, wherein each alternating column is shorter than columns 605A and 606A (e.g., has fewer apertures). In some embodiments, the zigzag-edge rectangular aperture array 626A may have fewer alternating columns than the zigzag-edge rectangular aperture array 602A, wherein each alternating column is longer than columns 605A and 606A (e.g., has more apertures).

[0070] Figure 6B shows an example graph illustrating the number of fine beams available for scanning a wafer in a given FOV using different aperture arrays at varying fine beam spacings. The horizontal axis represents the fine beam spacing decreasing in micrometers from left to right. The vertical axis represents the number of fine beams available for scanning a wafer in a given FOV. Curve 608B represents the number of fine beams available for scanning a wafer in continuous scan mode using a hexagonal aperture array with varying fine beam spacing (e.g., hexagonal aperture array 502C in Figure 5C). Curve 610B represents the number of fine beams available for scanning a wafer in continuous scan mode using a serrated edge rectangular aperture array with varying fine beam spacing (e.g., serrated edge rectangular array 602A in Figure 6A). As shown in Figure 6B, since the number of fine beams available for the aperture array increases as the distance between each aperture decreases, the number of fine beams available for any aperture array increases as the fine beam spacing decreases. Because serrated-edge rectangular aperture arrays do not introduce unused areas when operating the imaging system in continuous scanning mode, they can achieve higher throughput and better performance than hexagonal aperture arrays. For example, in continuous scanning mode, a hexagonal aperture array with a fine beam spacing of 210 μm allows 161 fine beams to scan a wafer in the FOV, while a serrated-edge rectangular aperture array with a fine beam spacing of 210 μm allows 217 fine beams to scan a wafer in the same FOV.

[0071] Figure 7 illustrates an example of an aperture array 700 comprising a first set of apertures 702 forming a 2D hexagonal shape (e.g., hexagonal aperture array 402B of Figure 4B) and a second set of apertures forming a 2D serrated edge rectangular shape 704 (e.g., serrated edge rectangular aperture array 602A of Figure 6A). 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 columns of apertures offset in a direction perpendicular to (e.g., horizontally) extending thereon (e.g., vertically). Each offset column may extend from an edge of the hexagonal shape that extends at an angle greater than 90 degrees from the horizontal edge of the hexagonal shape.

[0072] In some embodiments, a multi-beam system (e.g., EBI system 100 of FIG. 1) can operate in different scanning modes. For example, a multi-beam system can operate in a skip scan mode for high-resolution applications and in a continuous scan mode for high-current applications. In some embodiments, the hexagonal set of aperture 702 (e.g., aperture 330 or 332 of FIG. 3B) can be controlled to operate in a pass-through state such that electrons from the primary electron beam (e.g., primary electron beam 202 of FIG. 2) can pass through the hexagonal set of aperture 702 during skip scan mode. During skip scan mode, the aperture of the serrated edge rectangle set of aperture 704 (e.g., aperture 334 of FIG. 3B), which is not shared with the hexagonal set of aperture 702 (e.g., serrated corner aperture 704A), 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 either of the following states: a deflection structure (e.g., deflection structure 324 or 326 in FIG. 3B) can guide an electron beam (e.g., electron beam 336 or 338 in FIG. 3B) straight through the aperture; or a blocking state can be established where a deflection structure (e.g., deflection structure 328 in FIG. 3B) can guide an electron beam (e.g., electron beam 340 in FIG. 3B) through a blanket (e.g., deflected away from the entry direction and hitting the wall of the aperture) and the electron beam can be blocked without passing through the aperture.

[0073] In some embodiments, the set of zigzag-edged rectangles of aperture 704 can be controlled to operate in a through state such that electrons from the primary electron beam can pass through the set of zigzag-edged rectangles of aperture 704 during continuous scan mode. During continuous scan mode, the aperture of the set of hexagons of aperture 702, which is not shared with the set of zigzag-edged rectangles of aperture 704, can be controlled to operate in a blocking state to block electrons from the primary electron beam from passing through the non-shared aperture. In some embodiments, the darker area at the center of aperture array 700 can be controlled to always operate in a through state such that electrons from the primary electron beam can pass through the aperture of the aperture during both skip scan mode and continuous scan mode.

[0074] Although Figure 7 does not explicitly show the apertures along the boundary of the aperture array 700, it should be understood that the apertures exist on the boundary to provide the aperture array 700 with its unique shape.

[0075] Figure 8 illustrates an example procedure 800 for inspecting a wafer. The procedure may include an inspection system (e.g., the EBI system 100 of Figure 1) that can scan a wafer (e.g., sample 208 of Figure 2) using an aperture array (e.g., hexagonal aperture array 402B of Figure 4B; aperture array 602A of Figure 6A; aperture array 700 of Figure 7). The aperture array may include a first set of apertures forming a 2D hexagonal shape (e.g., the set of apertures 702 of Figure 7; hexagonal aperture array 402B of Figure 4B) and a second set of apertures forming a 2D rectangular shape with serrated edges (e.g., apertures 704 of Figure 7; serrated edge rectangular aperture array 602A of Figure 6A). The aperture array may have a hexagonal shape with four sets of serrated corner apertures (e.g., serrated corner apertures 704A of Figure 7). Each set of serrated corner apertures may include at least two columns of apertures offset in a direction perpendicular to the direction in which the columns extend (e.g., horizontally) (e.g., vertically). Each offset column may extend from an edge of the hexagonal shape that extends at an angle greater than 90 degrees from the horizontal edge of the hexagonal shape.

[0076] In step 801, the detection system can select a scanning mode from a first scanning mode and a second scanning mode for detecting the wafer. In the first scanning mode, a first 2D set of apertures of the aperture array can be used to detect the wafer. For example, the detection system can use the first 2D set of 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, the hexagonal set of apertures (e.g., apertures 330 or 332 in FIG. 3B) can be controlled to operate in a pass-through state so that electrons from the primary electron beam (e.g., primary electron beam 202 in FIG. 2) can pass through the hexagonal set of apertures during the skip scan mode. During the skip scan mode, the apertures of the serrated edge rectangle set of apertures (e.g., aperture 334 in FIG. 3B) that are not shared with the hexagonal set of apertures (e.g., serrated corner aperture 704A) can be controlled to operate in a blocking state to block electrons from the primary electron beam from passing through the non-shared apertures. For example, each aperture can be independently and individually controlled to be in either of the following states: a deflection structure (e.g., deflection structure 324 or 326 in FIG. 3B) can guide an electron beam (e.g., electron beam 336 or 338 in FIG. 3B) straight through the aperture; or a blocking state can be established where a deflection structure (e.g., deflection structure 328 in FIG. 3B) can guide an electron beam (e.g., electron beam 340 in FIG. 3B) through a blanket (e.g., deflected away from the entry direction and hitting the wall of the aperture) and the electron beam can be blocked without passing through the aperture.

[0077] In the second scanning mode, a second 2D set of apertures of the aperture array can be used to inspect the wafer. For example, a set of serrated edge rectangles of apertures can be controlled to operate in a through state so that electrons from the primary electron beam can pass through the set of serrated edge rectangles of apertures during continuous scanning mode. During continuous scanning mode, the apertures of a set of hexagonal apertures not shared with the set of serrated edge rectangles of 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 2D set of apertures can partially overlap with the first 2D set of apertures (e.g., the darker area in the center of the aperture array 700 of FIG. 7). The overlapping apertures can be controlled to always operate in a through state so that electrons from the primary electron beam can pass through the apertures during both skip scanning mode and continuous scanning mode.

[0078] In step 803, the detection 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 the set of rectangular zigzag edges of the apertures. On the other hand, if a skip scanning mode is selected, it is not necessary to rotate the aperture array. Furthermore, the passage and obstruction states of the aperture array can be adjusted accordingly.

[0079] The nature of the invention is described in the following numbered entries: 1. A microelectromechanical system (MEMS) structure, comprising: A first two-dimensional (2D) set of apertures, configured for use in a first scanning mode; and A second 2D set of apertures, configured for a second scanning mode different from the first scanning mode; The second 2D set of apertures partially overlaps with the first 2D set of apertures. 2. As in clause 1, wherein the first 2D set of apertures comprises an array of apertures forming a rectangular shape with serrated edges. 3. The structure as described in Clause 1, wherein the first 2D set of apertures includes apertures not used in the second scanning mode and the second 2D set of apertures includes apertures not used in the first scanning mode. 4. The structure of any one of items 1 to 3, wherein the first 2D set of apertures includes: First column aperture; Second column aperture; Third column aperture; Fourth row of apertures; in: The first, second, third, and fourth columns are parallel to each other in the first direction; The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction. 5. As in item 3, wherein the offset includes apertures that do not overlap in the second direction. 6. The structure of any one of items 4 to 5, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 7. As in item 6, the first, second, third and fourth columns alternate in the first direction. 8. The structure of any one of items 1 to 7, wherein the second 2D set of apertures comprises an array of apertures forming a hexagonal shape. 9. The structure of any one of items 1 to 8, wherein the first scanning mode is a continuous scanning mode. 10. As in item 9, wherein the first 2D set of apertures is configured to rotate when operating in continuous scan mode. 11. The structure of any one of items 1 to 10, wherein the second scan mode is a skip scan mode. 12. A microelectromechanical system (MEMS) structure, comprising: The first two-dimensional (2D) set of apertures, comprising an array of apertures forming a rectangular shape with serrated edges; and The second 2D set of apertures comprises an array of apertures forming a hexagonal shape; The second 2D set of apertures partially overlaps with the first 2D set of apertures; and The first 2D set of apertures is configured for use in a first scanning mode, and the second 2D set of apertures is configured for use in a second scanning mode different from the first scanning mode. 13. The structure of clause 12, wherein the first 2D set of apertures includes apertures not used in the second scanning mode and the second 2D set of apertures includes apertures not used in the first scanning mode. 14. The structure of any one of items 12 to 13, wherein the first 2D set of apertures includes: First column aperture; Second column aperture; Third column aperture; Fourth row of apertures; in: The first, second, third, and fourth columns are parallel to each other in the first direction; The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction. 15. The structure of item 14, wherein the offset is contained in apertures that do not overlap in the second direction. 16. The structure of any one of items 14 to 15, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 17. As in item 16, the first, second, third and fourth columns alternate in the first direction. 18. The structure of any one of items 12 to 17, wherein the first scanning mode is a continuous scanning mode. 19. The structure of item 18, wherein the first 2D set of apertures is configured to rotate when operating in continuous scan mode. 20. The structure of any one of items 12 to 19, wherein the second scan mode is a skip scan mode. 21. A microelectromechanical system (MEMS) structure, comprising: The array of apertures forms a hexagonal shape with four sets of apertures having serrated corners; Each set of sawtooth corner apertures includes: Two rows of apertures extending in a first direction, wherein the two rows of apertures are offset in a second direction perpendicular to the first direction, wherein Each column extends from the first edge of the hexagonal shape in a first direction, and the first edge of the hexagonal shape extends more than 90 degrees from the second edge of the hexagonal shape extending in the first direction in a third direction. 22. The structure of item 21, wherein the array comprises a first 2D set of apertures forming a rectangular shape with serrated edges. 23. The structure of item 22, wherein the serrated edge rectangular shape comprises at least some of the apertures forming the hexagonal shape and four sets of serrated corner apertures. 24. The structure of any one of items 21 to 23, wherein the array comprises a second 2D set of apertures forming a hexagonal shape. 25. The structure of any one of clauses 22 to 24, wherein the first 2D set of apertures includes apertures not used in the second scanning mode and the second 2D set of apertures includes apertures not used in the first scanning mode. 26. The structure of any of items 21 to 25, wherein the offset is contained in apertures that do not overlap in the second direction. 27. The structure of any one of items 25 to 26, wherein the first scanning mode is a continuous scanning mode. 28. The structure of any of items 25 to 27, wherein the first 2D set of apertures is configured to rotate when operating in continuous scan mode. 29. The structure of any one of items 25 to 28, wherein the second scan mode is a skip scan mode. 30. A microelectromechanical system (MEMS) structure, comprising: First column aperture; The second column of apertures is positioned below the first column of apertures; The third column of apertures is positioned below the second column of apertures; and The fourth aperture is positioned below the third aperture. in: The first, second, third, and fourth columns are parallel to each other in the first direction; and The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; 31. The structure of item 30, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 32. As in item 31, wherein the first, second, third and fourth columns alternate in the first direction. 33. The structure of any one of items 30 to 32, wherein the structure is configured for use in the continuous scanning mode of a multi-beam detection system. 34. The structure of item 33, wherein the structure is configured to rotate when operating in continuous scan mode. 35. A microelectromechanical system (MEMS) structure, comprising: The first structure includes: First column aperture; Second column aperture; Third column aperture; Fourth row of apertures; in: The first, second, third, and fourth columns are parallel to each other in the first direction; and The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; The second structure includes an array of apertures forming a hexagonal shape; and The first structure is superimposed on the second structure. 36. The MEMS structure of item 35, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 37. The MEMS structure as described in item 36, wherein the first, second, third and fourth columns alternate in the first direction. 38. A MEMS structure as described in any of items 35 to 37, wherein the first structure is configured for use in a continuous scanning mode of a multi-beam detection system. 39. The MEMS structure of item 38, wherein the first structure is configured to rotate when operating in continuous scan mode. 40. A MEMS structure as described in any of items 35 to 39, wherein the second structure is configured for use in a skip scan mode of a multi-beam detection system. 41. A multi-beam system for generating a plurality of beams for detecting a wafer positioned on a stage, the system comprising: The first structure includes: First column aperture; Second column aperture; Third column aperture; Fourth row of apertures; in: The first, second, third, and fourth columns are parallel to each other in the first direction; and The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction; The second structure includes an array of apertures forming a hexagonal shape; and The controller includes circuitry configured to perform continuous scan detection using a first structure or skip scan detection using a second structure. 42. The system of clause 41, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 43. The system as described in clause 42, wherein the first, second, third and fourth columns alternate in the first direction. 44. A system as described in any of items 41 to 43, wherein the circuitry is further configured to rotate the first structure when performing continuous scan detection. 45. A method for inspecting a wafer positioned on a stage, the method comprising: A scanning mode is selected from the first scanning mode and the second scanning mode for wafer inspection, wherein: In the first scanning mode, the first two-dimensional (2D) set of apertures of the aperture array is used to inspect the wafer, and In the second scanning mode, a second 2D set of apertures of the aperture array is used to inspect the wafer, wherein the second 2D set of apertures partially overlaps with the first 2D set of apertures; and Configure the aperture array based on the selected scanning mode. 46. ​​The method of clause 45, wherein the first 2D set of apertures comprises an array of apertures forming a rectangular shape with serrated edges. 47. The method of clause 45, wherein the first 2D set of apertures includes apertures not used in the second scanning mode and the second 2D set of apertures includes apertures not used in the first scanning mode. 48. The method of any one of clauses 45 to 47, wherein the first 2D set of apertures comprises: First column aperture; Second column aperture; Third column aperture; Fourth row of apertures; in: The first, second, third, and fourth columns are parallel to each other in the first direction; The first and third columns are offset from the second and fourth columns in a second direction perpendicular to the first direction. 49. The method of clause 47, wherein the offset is included in the apertures that do not overlap in the second direction. 50. The method of any one of clauses 48 to 49, wherein the first and third columns have a first length and the second and fourth columns have a second length, and the first length is greater than the second length in the second direction. 51. As in item 50, wherein the first, second, third and fourth columns alternate in the first direction. 52. The method of any one of clauses 45 to 51, wherein the second 2D set of apertures comprises an array of apertures forming a hexagonal shape. 53. The method of any one of items 45 to 52, wherein the first scanning mode is a continuous scanning mode. 54. The method of clause 53, wherein the first 2D set of apertures is configured to rotate when operating in continuous scan mode. 55. The method of any one of items 45 to 54, wherein the second scanning mode is a skip scanning mode.

[0080] It should be noted that many other examples of aperture arrays are possible and are not limited to the examples presented in this invention.

[0081] Non-transitory computer-readable media may be provided, storing instructions for a processor (e.g., the processor of controller 109 in Figures 1 and 2) to perform: select a mode, configure an aperture array based on the selected mode, perform image processing, data processing, fine beam scanning, database management, graphic display, operation of a charged particle beam device or another imaging apparatus, or similar. Common forms of non-transitory media include, for example: floppy disks, flexible disks, hard disks, solid-state drives, magnetic tapes or any other magnetic data storage media; CD-ROMs; any other optical data storage media; any physical media with a perforated pattern; RAM, PROM, and EPROM; FLASH-EPROM or any other flash memory; NVRAM; cache memory; temporary registers; any other memory chips or cartridges; and their networked versions.

[0082] It should be understood that the embodiments of the present invention are not limited to the exact constructions described above and illustrated in the accompanying drawings, and various modifications and changes can be made without departing from the scope of the present invention.

[0083] 100: Electron Beam Detection System 101:Main chamber 102: Loading / Locking Chamber 104: Electron Beam Tools 106: Equipment front-end module 106a: First loading port 106b: Second loading port 109: Controller 201: Electronic Source 202: Primary Electron Beam 203: Primary Beam Crossover 204: Principal Axis 207: Sample Holder 208: Sample 209: Mobile Platform 210: Condenser Lens 211: Primary Fine Beam 212: Primary fine beam 213: Primary Fine Beam 220: Source conversion unit 221: Detecting the light spot 222: Detecting the light spot 223: Detecting the light spot 230: Primary Projection System 231: Objective lens 232: Deflection Scanning Unit 233: Beam splitter 240: Electronic detection device 241: Detection element 242: Detection element 243: Detection element 250: Secondary projection system 251: Secondary optical axis 261: Secondary electron beam 262: Secondary electron beam 263: Secondary electron beam 271: Coulomb aperture plate 302: Peripheral Electronics 304: Aperture 306: Aperture 308: Aperture 314: Fine Beam 316: Fine Beam 318: Fine Beam 324: Deflection Structure 326: Deflection Structure 328: Deflection Structure 330: Cut-off aperture 332: Cut-off aperture 334: Cut-off aperture 336: Electron Beam 338: Electron Beam 340: Electron Beam 350: MEMS aperture array 402A: Aperture Array 402B: Aperture Array 404A: Aperture 404B: Aperture 408C: Curve 410C: Curve 502A: Rotated Hexagonal Aperture Array 502B: Rotated Hexagonal Aperture Array 502C: Rotated Hexagonal Aperture Array 504A: Aperture 504B: Aperture 504C: Aperture 506A: District 506B: District 506C: Zone 508: Curve 510: Curve 602: Sawtooth-edged rectangular aperture array 602A: Aperture Array 604A: Aperture 605A: First row aperture 606A: Second row aperture 608B: Curve 610B: Curve 624A: Sawtooth-edged rectangular aperture array 626A: Sawtooth-edged rectangular aperture array 700: Aperture Array 702: 2D hexagonal shape 704:2D jagged edge rectangular shape 704A: Serrated corner aperture 800: Program 801: Steps 803: Steps

Claims

1. A microelectromechanical system (MEMS) aperture array, comprising: a first set of apertures, including: a first column of apertures; a second column of apertures positioned below the first column of apertures; a third column of apertures positioned below the second column of apertures; and a fourth column of apertures positioned below the third column of apertures; wherein: The first column of apertures, the second column of apertures, the third column of apertures, and the fourth column of apertures are parallel to each other in a first direction; and the first column of apertures and the third column of apertures are offset from the second column of apertures and the fourth column of apertures in a second direction perpendicular to the first direction; and a second set of apertures comprising an array of apertures forming a hexagonal shape, wherein the first set of apertures and the second set of apertures are configured for different scanning modes, and wherein the second set of apertures partially overlaps with the first set of apertures.

2. The MEMS aperture array of claim 1, wherein the first column of apertures and the third column of apertures have a first length and the second column of apertures and the fourth column of apertures have a second length, and the first length is greater than the second length in the second direction.

3. The MEMS aperture array of claim 2, wherein the first column of apertures, the second column of apertures, the third column of apertures and the fourth column of apertures alternate in the first direction.

4. A MEMS aperture array as described in any of claims 1 to 3, wherein the MEMS aperture array is configured for use in a continuous scanning mode of a multi-beam detection system.

5. The MEMS aperture array of claim 4, wherein the MEMS aperture array is configured to rotate when operating in the continuous scan mode.

6. A non-transitory computer-readable medium storing instructions, which, when executed by a processor, cause the processor to perform a method for detecting a wafer positioned on a stage, the method comprising: selecting a scan mode from a first scan mode and a second scan mode for detecting the wafer, wherein: In the first scan mode, a first set of apertures of an aperture array is used to detect the wafer, and in the second scan mode, a second set of apertures of the aperture array is used to detect the wafer, wherein the second set of apertures partially overlaps with the first set of apertures; and the aperture array is configured based on the selected scan mode.

7. The computer-readable medium of claim 6, wherein the first set of apertures includes apertures not used in the second scan mode and the second set of apertures includes apertures not used in the first scan mode.

8. The computer-readable medium of claim 6, wherein the first set of apertures comprises: a first column of apertures; a second column of apertures; a third column of apertures; a fourth column of apertures; wherein: The first column of apertures, the second column of apertures, the third column of apertures, and the fourth column of apertures are parallel to each other in a first direction; the first column of apertures and the third column of apertures are offset from the second column of apertures and the fourth column of apertures in a second direction perpendicular to the first direction.

9. The computer-readable medium as claimed in claim 8, wherein the offset includes apertures that do not overlap in the second direction.

10. The computer-readable medium as requested in item 6, wherein the first scanning mode is a continuous scanning mode and the second scanning mode is a skip scanning mode.

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