Systems and methods for increasing throughput during voltage contrast inspection using points of interest and signals

Abstract

Systems and methods for inspecting a sample. Systems and methods may include determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.

Description

SYSTEMS AND METHODS FOR INCREASING THROUGHPUT DURING VOLTAGE CONTRAST INSPECTION USING POINTS OF INTEREST AND SIGNALSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 514,537 which was filed on July 19, 2023 and which is incorporated herein in its entirety by reference.FIELD

[0002] The description herein relates to the field of inspection and charged particle systems, and more particularly to methods for increasing throughput during voltage contrast inspection using points of interest and signals.BACKGROUND

[0003] In manufacturing processes of integrated circuits (ICs), unfinished or finished circuit components are inspected to ensure that they are manufactured according to design and are free of defects. An inspection system utilizing an optical microscope typically has resolution down to a few hundred nanometers; and the resolution is limited by the wavelength of light. As the physical sizes of IC components continue to reduce down to sub- 100 or even sub- 10 nanometers, inspection systems capable of higher resolution than those utilizing optical microscopes are needed.

[0004] A charged particle (e.g., electron) beam microscope, such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM), capable of resolution down to less than a nanometer, serves as a practicable tool for inspecting IC components having a feature size that is sub- 100 nanometers. With a SEM, electrons of a single primary electron beam, or electrons of a plurality of primary electron beams, can be focused on locations of interest of a wafer under inspection. The primary electrons interact with the wafer and may be backscattered or may cause the wafer to emit secondary electrons. The intensity of the electron beams comprising the backscattered electrons and the secondary electrons may vary based on the properties of the internal and external structures of the wafer, and thereby may indicate whether the wafer has defects.SUMMARY

[0005] Embodiments of the present disclosure provide systems and methods for increasing throughput during voltage contrast inspection using points of interest and signals. In some embodiments, systems, methods, and non-transitory computer readable mediums may include determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging ofthe corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.

[0006] In some embodiments, systems, methods, and non-transitory computer readable mediums may include determining a pattern of one or more inspection features on the sample in a field of view (FOV); charging the sample at one or more locations corresponding to the pattern of one or more inspection features; scanning the sample at one or more locations corresponding to the pattern of inspection features; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on detected one or more particle emissions.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system, consistent with embodiments of the present disclosure.

[0008] Fig. 2A is a schematic diagram illustrating an exemplary multi-beam system that is part of the exemplary charged particle beam inspection system of Fig. 1, consistent with embodiments of the present disclosure.

[0009] Fig. 2B is a schematic diagram illustrating an exemplary single -beam system that is part of the exemplary charged particle beam inspection system of Fig. 1, consistent with embodiments of the present disclosure.

[0010] Fig. 3 is an exemplary graph showing a yield rate of secondary electrons relative to landing energy of primary electron beamlets, consistent with embodiments of the present disclosure.

[0011] Fig. 4 is a schematic diagram illustrating an exemplary a voltage contrast response of a wafer, consistent with embodiments of the present disclosure.

[0012] Fig. 5 shows an exemplary process for inspection of a sample, consistent with embodiments of the present disclosure.DETAILED DESCRIPTION

[0013] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the disclosure. Instead, they are merely examples of apparatuses and methods consistent with aspects related to the subject matter recited in the appended claims. For example, although some embodiments are described in the context of utilizing electron beams, the disclosure is not so limited. Other types of charged particle beams may be similarly applied. Furthermore, other imaging systems may be used, such as optical imaging,photodetection, x-ray detection, extreme ultraviolet inspection, deep ultraviolet inspection, or the like, in which they generate corresponding types of images.

[0014] Electronic devices are constructed of circuits formed on a piece of silicon called a substrate. Many circuits may be formed together on the same piece of silicon and are called integrated circuits or ICs. The size of these circuits has decreased dramatically so that many more of them can fit on the substrate. For example, an IC chip in a smart phone can be as small as a thumbnail and yet may include over 2 billion transistors, the size of each transistor being less than 1 / 1000th the size of a human hair.

[0015] Making these extremely small ICs is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. Errors in even one step have the potential to result in defects in the finished IC rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects to maximize the number of functional ICs made in the process, that is, to improve the overall yield of the process.

[0016] One component of improving yield is monitoring the chip making process to ensure that it is producing a sufficient number of functional ICs. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection may be carried out using a scanning electron microscope (SEM). A SEM can be used to image these extremely small structures, in effect, taking a “picture” of the structures of the wafer. The image can be used to determine if the structure was formed properly, and also if it was formed at the proper location. If the structure is defective, then the process can be adjusted so the defect is less likely to recur. Defects may be generated during various stages of semiconductor processing. For the reason stated above, it is important to find defects accurately and efficiently as early as possible.

[0017] The working principle of a SEM is similar to a camera. A camera takes a picture by receiving and recording brightness and colors of light reflected or emitted from people or objects. A SEM takes a “picture” by receiving and recording energies or quantities of electrons reflected or emitted from the structures. Before taking such a “picture,” an electron beam may be projected onto the structures, and when the electrons are reflected or emitted (“exiting”) from the structures, a detector of the SEM may receive and record the energies or quantities of those electrons to generate an image. To take such a “picture,” some SEMs use a single electron beam (referred to as a “single-beam SEM”), while some SEMs use multiple electron beams (referred to as a “multi-beam SEM”) to take multiple “pictures” of the wafer. By using multiple electron beams, the SEM may project more electron beams onto the structures for obtaining these multiple “pictures,” resulting in more electrons exiting from the structures. Accordingly, the detector may receive more exiting electrons simultaneously, and generate images of the structures of the wafer with a higher efficiency and a faster speed.

[0018] Typical voltage contrast (VC) inspections obtain a SEM image within a field of view (FOV), which contains features of interests on a sample. In typical VC inspections, during acquisition of SEM images, features under inspection are either positively or negatively charged by scanning a samplewith charged particle beams. The charging condition is controlled by properly setting the scan time and beam current of the primary electron beam. The charging condition may also be controlled by the landing energy of primary electron beamlets, which may control the yield of secondary electrons, resulting in positive or negative charging of features on a wafer. A typical system may identify defects at features based on the gray levels of those features.

[0019] Typical VC inspection systems suffer from constraints. For example, the entire area within a FOV is scanned even though the features of interest may be located in a smaller area of the sample. That is, features may be scattered across an area of the SEM image. Even though the points of interests on a sample may comprise a low percentage of the FOV, typical systems scan the entire area within the FOV. These typical systems reduce throughput during inspection due to the time spent scanning areas without points of interest.

[0020] Additionally, SEM images that contain the gray levels of the features need to be acquired prior to conducting the inspection. This method of inspection results in low throughput during inspection due to the time required to obtain SEM images prior to inspection, obtain SEM images of the entire area within a FOV, and due to the raster scan nature of inspection tool.

[0021] Typical VC inspection systems also suffer from imprecise tuning. In existing systems, the gray level of a feature needs to be fine-tuned to a certain value or range and the VC of a feature is determined by the charging condition at the feature. For example, fine-tuning the electron dose at a feature is needed so that the defects in a sample can be easily identified (e.g., by resulting in distinct contrast in grey levels from the grey levels of a normal feature, by resulting in distinct difference in signals from the signals of a normal feature, etc.).

[0022] The charging condition may be affected by the structure and properties of the features, the electric field around the feature, and the electron dose per unit time introduced by the primary beam to the sample. The charging condition may also be affected by the landing energy of primary electron beamlets. The properties of the features include the parasitic parameters such as resistance and capacitance. Properly charging the features in typical systems includes controlling the electric field around the features, introducing light induced leakage, tuning the scan rate, tuning the beam current to adjust the electron dose per unit time on the features, and controlling the landing energy of on the sample. However, these typical methods of tuning the charging conditions at the features are imprecise and inefficient. For example, adjusting the scan rate to vary the electron dose into a sample cannot feasibly be fine-tuned.

[0023] The disclosed embodiments provide systems and methods that address some or all of these disadvantages by performing VC inspection based on points of interest and signals generated by the inspection system. For example, one or more charged particle beams may be directed only to one or more locations of inspection features on the sample (e.g., point of interest) in a discrete manner of scanning rather than a typical line-by-line continuous scanning. Advantageously, only points of interest on the sample may be exposed to a charged particle beam.

[0024] In some embodiments, the system may adjust a scan rate of the one or more charged particle beams depending on whether a location in the FOV corresponds to an inspection feature or not. For example, the system may decrease the scan rate (and increase the dwell time) over inspection features and increase the scan rate over areas between each inspection feature. This method is particularly advantageous when inspection features are scattered across a sample.

[0025] In some embodiments, a controller or signal processing system may determine defect information based on one or more signals generated by the inspection system. For example, each signal corresponding to an inspection feature may vary based on the amount of accumulated charge on the inspection feature. In typical inspection systems, the system may generate voltage contrast images and analyze the voltage contrast images to determine whether features on a sample include a defect. Advantageously, the disclosed embodiments may determine the defect information without constructing any images of the inspection features using the one or more signals, thereby increasing throughput during VC inspection.

[0026] Relative dimensions of components in drawings may be exaggerated for clarity. Within the following description of drawings, the same or like reference numbers refer to the same or like components or entities, and only the differences with respect to the individual embodiments are described.

[0027] As used herein, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, if it is stated that a component may include A or B, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component may include A, B, or C, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0028] Without limiting the scope of the present disclosure, some embodiments may be described in the context of providing detectors and detection methods in systems utilizing electron beams. However, the disclosure is not so limited. Other types of charged particle beams may be similarly applied. Furthermore, systems and methods for detection may be used in other imaging systems, such as optical imaging, photon detection, x-ray detection, ion detection, etc.

[0029] Fig. 1 illustrates an exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure. EBI system 100 may be used for imaging. As shown in Fig. 1, EBI system 100 includes a main chamber 101, a load / lock chamber 102, an electron beam tool 104, and an equipment front end module (EFEM) 106. Electron beam tool 104 is located within main chamber 101. EFEM 106 includes a first loading port 106a and a second loading port 106b. EFEM 106 may include additional loading port(s). First loading port 106a and second loading port 106b receive wafer front opening unified pods (FOUPs) that contain wafers (e.g., semiconductor wafers or wafers made of other material(s)) or samples to be inspected (wafers and samples may be used interchangeably). A “lot” is a plurality of wafers that may be loaded for processing as a batch.

[0030] One or more robotic arms (not shown) in EFEM 106 may transport the wafers to load / lock chamber 102. Load / lock chamber 102 is connected to a load / lock vacuum pump system (not shown) which removes gas molecules in load / lock chamber 102 to reach a first pressure below the atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) may transport the wafer from load / lock chamber 102 to main chamber 101. Main chamber 101 is connected to a main chamber vacuum pump system (not shown) which removes gas molecules in main chamber 101 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subject to inspection by electron beam tool 104. Electron beam tool 104 may be a single-beam system or a multi-beam system.

[0031] A controller 109 is electronically connected to electron beam tool 104. Controller 109 may be a computer configured to execute various controls of EBI system 100. While controller 109 is shown in Fig. 1 as being outside of the structure that includes main chamber 101, load / lock chamber 102, and EFEM 106, it is appreciated that controller 109 may be a part of the structure.

[0032] In some embodiments, controller 109 may include one or more processors (not shown). A processor may be a generic or specific electronic device capable of manipulating or processing information. For example, the processor may include any combination of any number of a central processing unit (or “CPU”), a graphics processing unit (or “GPU”), an optical processor, a programmable logic controllers, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a Programmable Logic Array (PLA), a Programmable Array Logic (PAL), a Generic Array Logic (GAL), a Complex Programmable Logic Device (CPLD), a Field- Programmable Gate Array (FPGA), a System On Chip (SoC), an Application-Specific Integrated Circuit (ASIC), and any type circuit capable of data processing. The processor may also be a virtual processor that includes 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). A memory may be a generic or specific electronic device capable of storing codes and data accessible by the processor (e.g., via a bus). For example, the memory may include any combination of any number of a random-access memory (RAM), a read-only memory (ROM), an optical disc, a magnetic disk, a hard drive, a solid-state drive, a flash drive, a security digital (SD) card, a memory stick, a compact flash (CF) card, or any type of storage device. The codes may include an operating system (OS) and one or more application programs (or “apps”) for specific tasks. The memory may also be a virtual memory that includes one or more memories distributed across multiple machines or devices coupled via a network.

[0034] Embodiments of this disclosure may provide a single charged-particle beam imaging system (“single -beam system”). Compared with a single-beam system, a multiple charged-particle beam imaging system (“multi-beam system”) may be designed to optimize throughput for different scan modes. Embodiments of this disclosure provide a multi-beam system with the capability of optimizingthroughput for different scan modes by using beam arrays with different geometries and adapting to different throughputs and resolution requirements.

[0035] Reference is now made to Fig. 2A, which is a schematic diagram illustrating an exemplary electron beam tool 104 including a multi-beam inspection tool that is part of the EBI system 100 of Fig. 1, consistent with embodiments of the present disclosure. In some embodiments, electron beam tool 104 may be operated as a single-beam inspection tool that is part of EBI system 100 of Fig. 1. Multi-beam electron beam tool 104 (also referred to herein as apparatus 104) comprises 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 motorized stage 209 to hold a sample 208 (e.g., a wafer or a photomask) to be inspected. Multi-beam electron beam tool 104 may further comprise a secondary projection system 250 and an electron detection device 240. Primary projection system 230 may comprise an objective lens 231. Electron detection device 240 may comprise a plurality of detection elements 241, 242, and 243. A beam separator 233 and a deflection scanning unit 232 may be positioned inside primary projection system 230.

[0036] Electron source 201, Coulomb aperture plate 271, condenser lens 210, source conversion unit 220, beam separator 233, deflection scanning unit 232, and primary projection system 230 may be aligned with a primary optical axis 204 of apparatus 104. Secondary projection system 250 and electron detection device 240 may be aligned with a secondary optical axis 251 of apparatus 104.

[0037] Electron source 201 may comprise a cathode (not shown) and an extractor or anode (not shown), in which, during operation, 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 the anode to form a primary electron beam 202 that form a primary beam crossover (virtual or real) 203. Primary electron beam 202 may be visualized as being emitted from primary beam crossover 203.

[0038] Source conversion unit 220 may comprise an image-forming element array (not shown), an aberration compensator array (not shown), a beam-limit aperture array (not shown), and a pre-bending micro-deflector array (not shown). In some embodiments, the pre-bending micro-deflector array deflects a plurality of primary beamlets 211, 212, 213 of primary electron beam 202 to normally enter the beam-limit aperture array, the image-forming element array, and an aberration compensator array. In some embodiments, apparatus 104 may be operated as a single -beam system such that a single primary beamlet is generated. In some embodiments, condenser lens 210 is designed to focus primary electron beam 202 to become a parallel beam and be normally incident onto source conversion unit 220. The image-forming element array may comprise a plurality of micro-deflectors or micro-lenses to influence the plurality of primary beamlets 211, 212, 213 of primary electron beam 202 and to form a plurality of parallel images (virtual or real) of primary beam crossover 203, one for each of the primary beamlets 211, 212, and 213. In some embodiments, the aberration compensator array may comprise a field curvature compensator array (not shown) and an astigmatism compensator array (notshown). The field curvature compensator array may comprise a plurality of micro-lenses to compensate field curvature aberrations of the primary beamlets 211, 212, and 213. The astigmatism compensator array may comprise a plurality of micro-stigmators to compensate astigmatism aberrations of the primary beamlets 211, 212, and 213. The beam-limit aperture array may be configured to limit diameters of individual primary beamlets 211, 212, and 213. Fig. 2A shows three primary beamlets 211, 212, and 213 as an example, and it is appreciated that source conversion unit 220 may be configured to form any number of primary beamlets. Controller 109 may be connected to various parts of EBI system 100 of Fig. 1, such as source conversion unit 220, electron detection device 240, primary projection system 230, or motorized stage 209. In some embodiments, as explained in further details below, controller 109 may perform various image and signal processing functions. Controller 109 may also generate various control signals to govern operations of the charged particle beam inspection system.

[0039] Condenser lens 210 is configured to focus primary electron beam 202. Condenser lens 210 may further be configured to adjust electric currents of primary beamlets 211, 212, and 213 downstream of source conversion unit 220 by varying the focusing power of condenser lens 210. Alternatively, the electric currents may be changed by altering the radial sizes of beam-limit apertures within the beam-limit aperture array corresponding to the individual primary beamlets. The electric currents may be changed by both altering the radial sizes of beam-limit apertures and the focusing power of condenser lens 210. Condenser lens 210 may be an adjustable condenser lens that may be configured so that the position of its first principal plane is movable. The adjustable condenser lens may be configured to be magnetic, which may result in off-axis beamlets 212 and 213 illuminating source conversion unit 220 with rotation angles. The rotation angles change with the focusing power or the position of the first principal plane of the adjustable condenser lens. Condenser lens 210 may be an anti-rotation condenser lens that may be configured to keep the rotation angles unchanged while the focusing power of condenser lens 210 is changed. In some embodiments, condenser lens 210 may be an adjustable anti-rotation condenser lens, in which the rotation angles do not change when its focusing power and the position of its first principal plane are varied.

[0040] Objective lens 231 may be configured to focus beamlets 211, 212, and 213 onto a sample 208 for inspection and may form, in the current embodiments, three probe spots 221, 222, and 223 on the surface of sample 208. Coulomb aperture plate 271, in operation, is configured to block off peripheral electrons of primary electron beam 202 to reduce Coulomb effect. The Coulomb effect may enlarge the size of each of probe spots 221, 222, and 223 of primary beamlets 211, 212, 213, and therefore deteriorate inspection resolution.

[0041] Beam separator 233 may, for example, be a Wien filter comprising an electrostatic deflector generating an electrostatic dipole field and a magnetic dipole field (not shown in Fig. 2A). In operation, beam separator 233 may be configured to exert an electrostatic force by electrostatic dipole field on individual electrons of primary beamlets 211, 212, and 213. The electrostatic force is equal inmagnitude but opposite in direction to the magnetic force exerted by magnetic dipole field of beam separator 233 on the individual electrons. Primary beamlets 211, 212, and 213 may therefore pass at least substantially straight through beam separator 233 with at least substantially zero deflection angles.

[0042] Deflection scanning unit 232, in operation, is configured to deflect primary beamlets 211, 212, and 213 to scan probe spots 221, 222, and 223 across individual scanning areas in a section of the surface of sample 208. In response to incidence of primary beamlets 211, 212, and 213 or probe spots 221, 222, and 223 on sample 208, electrons emerge from sample 208 and generate three secondary electron beams 261, 262, and 263. Each of secondary electron beams 261, 262, and 263 typically comprise secondary electrons (having electron energy < 50eV) and backscattered electrons (having electron energy between 50eV and the landing energy of primary beamlets 211, 212, and 213). Beam separator 233 is configured to deflect secondary electron beams 261, 262, and 263 towards secondary projection system 250. Secondary projection system 250 subsequently focuses secondary electron beams 261, 262, and 263 onto detection elements 241, 242, and 243 of electron detection device 240. Detection elements 241, 242, and 243 are arranged to detect corresponding secondary electron beams 261, 262, and 263 and generate corresponding signals which are sent to controller 109 or a signal processing system (not shown), e.g., to construct images of the corresponding scanned areas of sample 208.

[0043] 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 comprise one or more pixels. The intensity signal output of a detection element may be a sum of signals generated by all the pixels within the detection element.

[0044] In some embodiments, controller 109 may comprise image processing system that includes an image acquirer (not shown), a storage (not shown). The image acquirer may comprise one or more processors. For example, the image acquirer may comprise a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, and the like, or a combination thereof. The image acquirer may be communicatively coupled to electron detection device 240 of apparatus 104 through a medium such as an electrical conductor, optical fiber cable, portable storage media, IR, Bluetooth, internet, wireless network, wireless radio, among others, or a combination thereof. In some embodiments, the image acquirer may receive a signal from electron detection device 240 and may construct an image. The image acquirer may thus acquire images of sample 208. The image acquirer may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, and the like. The image acquirer may be configured to perform adjustments of brightness and contrast, etc. of acquired images. In some embodiments, the storage 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 may be coupledwith the image acquirer and may be used for saving scanned raw image data as original images, and post-processed images.

[0045] In some embodiments, the image acquirer may acquire one or more images of a sample based on an imaging signal received from electron detection device 240. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image comprising a plurality of imaging areas. The single image may be stored in the storage. The single image may be an original image that may be divided into a plurality of regions. Each of the regions may comprise one imaging area containing a feature of sample 208. The acquired images may comprise multiple images of a single imaging area of sample 208 sampled multiple times over a time sequence. The multiple images may be stored in the storage. In some embodiments, controller 109 may be configured to perform image processing steps with the multiple images of the same location of sample 208.

[0046] In some embodiments, controller 109 may include measurement circuitries (e.g., analog-to- digital converters) to obtain a distribution of the detected secondary electrons. The electron distribution data collected during a detection time window, in combination with corresponding scan path data of each of primary beamlets 211, 212, and 213 incident on the wafer surface, can be used to reconstruct images of the wafer structures under inspection. The reconstructed images can be used to reveal various features of the internal or external structures of sample 208, and thereby can be used to reveal any defects that may exist in the wafer.

[0047] In some embodiments, controller 109 may control motorized stage 209 to move sample 208 during inspection of sample 208. In some embodiments, controller 109 may enable motorized stage 209 to move sample 208 in a direction continuously at a constant speed. In other embodiments, controller 109 may enable motorized stage 209 to change the speed of the movement of sample 208 over time depending on the steps of scanning process.

[0048] Although Fig. 2A shows that apparatus 104 uses three primary electron beams, it is appreciated that apparatus 104 may use one, two, or more number of primary electron beams. The present disclosure does not limit the number of primary electron beams used in apparatus 104. In some embodiments, apparatus 104 may be a SEM used for lithography. In some embodiments, electron beam tool 104 may be a single-beam system or a multi-beam system.

[0049] For example, as shown in Fig. 2B, an electron beam tool 100B (also referred to herein as apparatus 100B) may be a single -beam inspection tool that is used in EBI system 100, consistent with embodiments of the present disclosure. Apparatus 100B includes a wafer holder 136 supported by motorized stage 134 to hold a wafer 150 to be inspected. Electron beam tool 100B includes an electron emitter, which may comprise a cathode 103, an anode 121, and a gun aperture 122. Electron beam tool 100B further includes a beam limit aperture 125, a condenser lens 126, a column aperture 135, an objective lens assembly 132, and a detector 144. Objective lens assembly 132, in some embodiments, may be a modified SORIL lens, which includes a pole piece 132a, a control electrode132b, a deflector 132c, and an exciting coil 132d. In an imaging process, an electron beam 161 emanating from the tip of cathode 103 may be accelerated by anode 121 voltage, pass through gun aperture 122, beam limit aperture 125, condenser lens 126, and be focused into a probe spot 170 by the modified SORIL lens and impinge onto the surface of wafer 150. Probe spot 170 may be scanned across the surface of wafer 150 by a deflector, such as deflector 132c or other deflectors in the SORIL lens. Secondary or scattered primary particles, such as secondary electrons or scattered primary electrons emanated from the wafer surface may be collected by detector 144 to determine intensity of the beam and so that an image of an area of interest on wafer 150 may be reconstructed.

[0050] There may also be provided an image processing system 199 that includes an image acquirer 120, a storage 130, and controller 109. Image acquirer 120 may comprise one or more processors. For example, image acquirer 120 may comprise a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, and the like, or a combination thereof. Image acquirer 120 may connect with detector 144 of electron beam tool 100B through a medium such as an electrical conductor, optical fiber cable, portable storage media, IR, Bluetooth, internet, wireless network, wireless radio, or a combination thereof. Image acquirer 120 may receive a signal from detector 144 and may construct an image. Image acquirer 120 may thus acquire images of wafer 150. Image acquirer 120 may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, and the like. Image acquirer 120 may be configured to perform adjustments of brightness and contrast, etc. of acquired images. Storage 130 may be a storage medium such as a hard disk, random access memory (RAM), cloud storage, other types of computer readable memory, and the like. Storage 130 may be coupled with image acquirer 120 and may be used for saving scanned raw image data as original images, and post-processed images. Image acquirer 120 and storage 130 may be connected to controller 109. In some embodiments, image acquirer 120, storage 130, and controller 109 may be integrated together as one electronic control unit.

[0051] In some embodiments, image acquirer 120 may acquire one or more images of a sample based on an imaging signal received from detector 144. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image comprising a plurality of imaging areas that may contain various features of wafer 150. The single image may be stored in storage 130. Imaging may be performed on the basis of imaging frames.

[0052] The condenser and illumination optics of the electron beam tool may comprise or be supplemented by electromagnetic quadrupole electron lenses. For example, as shown in Fig. 2B, electron beam tool 100B may comprise a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lenses are used for controlling the electron beam. For example, first quadrupole lens 148 can be controlled to adjust the beam current and second quadrupole lens 158 can be controlled to adjust the beam spot size and beam shape.

[0053] Fig. 2B illustrates a charged particle beam apparatus in which an inspection system may use a single primary beam that may be configured to generate secondary electrons by interacting with wafer 150. Detector 144 may be placed along optical axis 105, as in the embodiment shown in Fig. 2B. The primary electron beam may be configured to travel along optical axis 105. Accordingly, detector 144 may include a hole at its center so that the primary electron beam may pass through to reach wafer 150.

[0054] Fig. 3 illustrates an exemplary graph showing a yield rate of secondary electrons relative to landing energy of primary electron beamlets, consistent with embodiments of the present disclosure. The graph illustrates the relationship of the landing energy of a primary electron beam (e.g., primary electron beam 202 of Fig. 2) and the yield rate of secondary electron beams). The yield rate indicates the number of secondary electrons that are produced in response to the impact of the primary electrons. For example, a yield rate greater than 1.0 indicates that more secondary electrons may be produced than the number of primary electrons that have landed on the wafer. Similarly, a yield rate of less than 1.0 indicates that less secondary electrons may be produced in response to the impact of the primary electrons.

[0055] As shown in the graph of Fig. 3, when the landing energy of the primary electrons is within a range from Ei to Ez, more secondary electrons may leave the surface of the wafer than land onto the surface of the wafer, which may result in a positive electrical potential at the surface of the wafer. In some embodiments, defect inspection may be performed in the foregoing range of landing energies, which is called “positive mode.” An electron beam tool (e.g., electron beam tool 104 of Fig. 2) may generate a darker voltage contrast image of a device structure with a more positive surface potential since a detection device (e.g., detection device 240 of Fig. 2) may receive less secondary electrons (see Fig. 4).

[0056] When the landing energy is lower than Ei or higher than Ez, less electrons may leave the surface of the wafer, thereby resulting in a negative electrical potential at the surface of the wafer. In some embodiments, defect inspection may be performed in this range of the landing energies, which is called “negative mode.” An electron beam tool (e.g., electron beam tool 104 of Fig. 2) may generate a brighter voltage contrast image of a device structure with a more negative surface potential a detection device (e.g., detection device 240 of Fig. 2) may receive more secondary electrons (see Fig. 4).

[0057] In some embodiments, the landing energy of the primary electron beams may be controlled by the total bias between the electron source and the wafer.

[0058] Fig. 4 illustrates a schematic diagram of a voltage contrast response of a wafer, consistent with embodiments of the present disclosure. In some embodiments, physical and electrical defects in a wafer (e.g., resistive shorts and opens, defects in deep trench capacitors, back end of line (BEOL) defects, etc.) can be detected using a voltage contrast method of a charged particle inspection system. Defect detection using voltage contrast images may use a pre-scanning process (i.e., a charging,flooding, neutralization, or prepping process), where charged particles are applied to an area of the wafer (e.g., sample 208 of Fig. 2) to be inspected before conducting the inspection.

[0059] In some embodiments, an electron beam tool (e.g., electron beam tool 104 of Fig. 2) may be used to detect defects in internal or external structures of a wafer by illuminating the wafer with a plurality of beamlets of a primary electron beam (e.g., plurality of beamlets 211, 212, or 213 of primary electron beam 202 of Fig. 2) and measuring a voltage contrast response of the wafer to the illumination. In some embodiments, the wafer may comprise a test device region 420 that is developed on a substrate 410. In some embodiments, test device region 420 may include multiple device structures 430 and 440 separated by insulating material 450. For example, device structure 430 is connected to substrate 410. In contrast, device structure 440 is separated from substrate 410 by insulating material 450 such that a thin insulator structure 470 (e.g., thin oxide) exists between device structure 440 and substrate 410.

[0060] The electron beam tool may generate secondary electrons (e.g., secondary electron beams 261, 262, or 263 of Fig. 2) from the surface of test device region 420 by scanning the surface of test device region 420 with a plurality of beamlets of a primary electron beam. As explained above, when the landing energy of the primary electrons is between Ei and Ez (i.e., the yield rate is greater than 1.0 in Fig. 3), more electrons may leave the surface of the wafer than land on the surface, thereby resulting in a positive electrical potential at the surface of the wafer.

[0061] As shown in Fig. 4, a positive electrical potential may build-up at the surface of a wafer. For example, after an electron beam tool scans test device region 420 (e.g., during a pre-scanning process), device structure 440 may retain more positive charges because device structure 440 is not connected to an electrical ground in substrate 410, thereby resulting in a positive electrical potential at the surface of device structure 440. In contrast, primary electrons with the same landing energy (i.e., the same yield rate) applied to device structure 430 may result in less positive charges retained in device structure 430 since positive charges may be neutralized by electrons supplied by the connection to substrate 410.

[0062] An image processing system (e.g., controller 109 of Fig. 2) of an electron beam tool may generate voltage contrast images 435 and 445 of corresponding device structures 430 and 440, respectively. For example, device structure 430 is shorted to the ground and may not retain built-up positive charges. Accordingly, when primary electron beamlets land on the surface of the wafer during inspection, device structure 430 may repel more secondary electrons thereby resulting in a brighter voltage contrast image. In contrast, because device structure 440 has no connection to substrate 410 or any other grounds, device structure 440 may retain a build-up of positive charges. This build-up of positive charges may cause device structure 440 to repel less secondary electrons during inspection, thereby resulting in a darker voltage contrast image.

[0063] An electron beam tool (e.g., multi-beam electron beam tool 104 of Fig. 2) may pre-scan the surface of a wafer by supplying electrons to build up the electrical potential on the surface of thewafer. After pre-scanning the wafer, the electron beam tool may obtain images of multiple dies within the wafer. In some embodiments, defects may be detected by comparing the differences in voltage contrast images from multiple dies. In some embodiments, defects may be identified by imaging the same locations (e.g., points of interests) in different dies and comparing voltage contrast images (e.g., grey levels in the images) of the same locations in different dies. In some embodiments, defects may be identified by imaging the same locations in different areas of the same die (where the areas have the same structure or layout) and comparing voltage contrast images of the different areas of the same die. Defects may be identified if the differences in voltage contrast or grey levels (e.g., due to different surface potentials caused by different electrical properties at the points of interest) exceed a predefined threshold. Pre-scanning is applied to the wafer under the assumption that the electrical surface potential built-up on the surface of the wafer during pre-scanning will be retained during inspection and will remain above the detection threshold of the electron beam tool.

[0064] In some embodiments, an effect of leakage current may occur in a structure with improperly formed materials or a high resistance metal layer, for example a cobalt silicide (e.g., CoSi, CoSiz, CozSi, Co sSi, etc.) layer between a tungsten plug and a source or drain area of a field-effect transistor (FET).

[0065] A defective etching process may leave a thin oxide resulting in unwanted electrical blockage (e.g., open circuit) between two structures (e.g., device structure 440 and substrate 410) intended to be electrically connected. For example, device structures 430 and 440 may be designed to make contact with substrate 410 and function identically, but due to manufacturing errors, insulator structure 470 may exist in device structure 440. In this case, insulator structure 470 may represent a defect susceptible to a breakdown effect.

[0066] Reference is now made to Fig. 5, an exemplary process 500 for inspection of a sample, consistent with embodiments of the present disclosure. It should be understood that process 500 may be performed in a multi-beam environment (e.g., electron beam tool 104 of Fig. 2A) or in a single beam environment (e.g., electron beam tool 104 of Fig. 2B).

[0067] At step 502, a system (e.g., electron beam tool 104 of Fig. 2A, electron beam tool 104 of Fig. 2B) may determine a plurality of locations on a sample (e.g., sample 208 of Fig. 2A, wafer 150 of Fig. 2B), each location corresponding to an inspection feature on the sample in a field of view (FOV).

[0068] In some embodiments, each location corresponding to an inspection feature on the sample in the FOV may be determined based on layout data. In some embodiments, a pattern of features of a sample may be a layout design, which may be stored in a layout file for a wafer design. The layout file can be in a Graphic Database System (GDS) format, Graphic Database System II (GDS II) format, an Open Artwork System Interchange Standard (OASIS) format, a Caltech Intermediate Format (CIF), etc. The wafer design may include patterns or structures for inclusion on the wafer. The patterns or structures can be mask patterns used to transfer features from the photolithography masks or reticles to a wafer. In some embodiments, a layout in GDS or OASIS format, among others, maycomprise feature information stored in a binary file format representing planar geometric shapes, text, and other information related to the wafer design. In some embodiments, a layout design may correspond to a FOV of an inspection system (e.g., a FOV of an inspection system may include one or more layout structures of a layout design).

[0069] For example, patterns of the sample (including periodic or repeating patterns of features) may be acquired from the layout data. In some embodiments, artificial intelligence (Al) and machine learning algorithms may be used to facilitate pattern acquisition and a scan path for inspection to further improve efficiency of the inspection. In some embodiments, Al and machine learning may be used to learn patterns of a sample based on previously obtained images or layout data.

[0070] In some embodiments, layout data for the sample may not be available or the pattern of the sample may be unknown. In these cases, the inspection system may scan a portion of the sample and generate at least one image based on the scanned portion of the sample. The inspection system may learn the patterns of features on the sample based on the image (e.g., based on periodic or repeating patterns of features). In some embodiments, Al and machine learning algorithms may be used to facilitate pattern acquisition and a scan path for inspection to further improve efficiency of the inspection. In some embodiments, Al and machine learning may be used to learn patterns of a sample based on previously obtained images.

[0071] In some embodiments, the system may align the sample with the inspection tool based on the known pattern of the sample (e.g., the sample may be aligned with the inspection tool such that based on the pattern, line features have the correct spacing between each line, line features are oriented in the correct direction). In some embodiments, the system may scan patterns on the sample (e.g., even when patterns of the sample are known or learned) to facilitate alignment of the sample. In some embodiments, alignment of the sample with the inspection tool may include adjusting the stage (e.g., motorized stage 209 of Fig. 2A, motorized stage 134 of Fig. 2B), adjusting the sample, adjusting scanning settings, etc.

[0072] In some embodiments, a location corresponding to an inspection feature may include a plurality of locations surrounding or near the inspection feature to account for misalignment errors. In some embodiments, the system may determine a plurality of locations surrounding or near the inspection feature, as opposed to scanning the entire area of the FOV, to increase inspection throughput. In some embodiments, the system may determine a plurality of locations such that a smaller area, which covers the points of interests, of a sample may be scanned. The system may generate SEM images of these scanned smaller areas and voltage contrast inspection may be used to identify features in the image and compare the gray level of the features to determine whether any defects are present. As a result, throughput may be improved since only part of the FOV, instead of the entire area within the FOV, is scanned.

[0073] At step 504, the system may provide one or more charged particle beams (e.g., primary beamlets 211, 212, 213 of primary electron beam 202 of Fig. 2A, primary electron beam 161 of Fig.2B) to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations. In some embodiments, before providing the one or more charged particle beams to the sample, a light source of the system (e.g., an ACC module) may be configured to emit one or more light beams (e.g., laser beams) at a corresponding location of the plurality of locations. For example, emitted light beams may illuminate points of interest of the sample, thereby adjusting or controlling the accumulated charge on the points of interest (e.g., charging the points of interest).

[0074] For example, one or more charged particle beams may be directed only to locations of inspection features on the sample (e.g., point of interest) in a discrete manner of scanning rather than a typical line-by-line continuous scanning. Advantageously, only points of interest on the sample may be exposed to a charged particle beam, thereby increasing throughput.

[0075] In some embodiments, the system may adjust a scan rate of the one or more charged particle beams depending on whether a location in the FOV corresponds to an inspection feature or not. For example, the system may decrease the scan rate (and increase the dwell time) over inspection features and increase the scan rate over areas between each inspection feature. This method is particularly advantageous when inspection features are scattered across a sample.

[0076] At step 506, the system may detect, for each location, particle emissions (e.g., secondary electron beams 261, 262, and 263 of Fig. 2A) resulting from the adjusted charge of the corresponding location. As discussed above, a beam separator (e.g., beam separator 233 of Fig. 2A) may be configured to deflect secondary electron beams (e.g., secondary electron beams 261, 262, and 263 of Fig. 2A) towards a secondary projection system (e.g., secondary projection system 250 of Fig. 2A). The secondary projection system may subsequently focus the secondary electron beams onto detection elements (e.g., detection elements 241, 242, and 243 of Fig. 2A) of an electron detection device (e.g., electron detection device 240 of Fig. 2A). The detection elements may be arranged to detect corresponding secondary electron beams.

[0077] The system may generate a plurality of signals, each signal corresponding to a particle emission of the plurality of particle emissions. For example, the detection elements may generate corresponding signals.

[0078] The system may analyze the plurality of signals. In some embodiments, the generated signals may be sent to a controller (e.g., controller 109 of Fig. 2A) or a signal processing system to be analyzed.

[0079] In some embodiments, resistance-capacitance (RC) data may be obtained from the generated signals and may be used to determine certain charge characteristics of a feature (e.g., whether a feature on the sample is grounded, whether a feature is open, whether a feature is shorted, etc.). In some embodiments, a charged particle beam may need to dwell at each feature on a sample for a predefined period of time. During the predefined period of time, a detection system may sample a generated signal at a plurality of times to determine a dynamic property of a feature on the sample (e.g., the voltage change vs. time). Based on the group of data, rather than a single data point of onesignal, the system may acquire a better estimation of the RC value of the feature. During this period of time, the beam current intensity may be constant or may be modulated (e.g., pulse modulated.). The modulation should be synchronized to the sampling in the detection channel. The light shining on the sample may also be either constant or modulated. If the light shining on the sample is modulated, the modulation should also be synchronized to the sampling of the detection system.

[0080] At step 508, the system may determine, for each location of interest, defect information of the sample based on the detected particle emissions. In some embodiments, the controller or signal processing system may determine defect information (e.g., whether an inspection feature contains a defect or is a normal functioning feature) based on the analyzed plurality of signals. For example, each signal corresponding to an inspection feature may vary based on the amount of accumulated charge on the inspection feature. In typical existing inspection systems, the system may generate voltage contrast images and analyze the voltage contrast images to determine whether features on a sample include a defect. When a signal is above or below a certain threshold, the controller may determine that the corresponding inspection feature includes a defect. Advantageously, the controller may determine the defect information without constructing any images of the inspection features using the signals.

[0081] In some embodiments, the system may modulate the beam current to provide more flexibility and to increase throughput during inspection. Typical systems adjust the scan rate to adjust the electron dose on features of a sample. However, scan rate adjustments cannot be fine-tuned. The disclosed embodiments may adjust the electron dose of an inspection feature (e.g., by tuning an electron beam source to vary the beam current, by using a fast blanker, by using an Advanced Charge Control (ACC), etc.), thereby improving the distinction between signals corresponding to defects on a sample and signals corresponding to normal features on the sample. For example, an ACC module may be employed to illuminate a light beam, such as a laser beam, on the inspection features, so as to control the accumulated charges due to effects such as photoconductivity, photoelectric, or thermal effects.

[0082] The disclosed embodiments are particularly advantageous and time-saving when points of interest are located further apart from each other on a sample because the areas on the sample in between the points of interest do not need to be scanned. Moreover, the amount of data that needs to be processed during inspection is reduced since only signals of points of interests are measured, instead of analyzing SEM images of the entire sample. An additional advantage of the reduced data is that any algorithms used in the system can be greatly simplified, which may help reduce the data analysis loads on the backend systems and the data transfer load from detection channel to the image computers. The inspection algorithm could even be run by a low power processor at the detection channel side. This advantage helps to improve the power efficiency of the system.

[0083] The disclosed embodiments may enhance the single beam VC inspection throughput by at least 1 to 2 orders of magnitudes due to scanning only scattered points of interest on the wafer ratherthan scanning the entire wafer area and obtaining SEM images of the entire wafer area. An efficiency factor FAmay be used to describe this increase in throughput. In a single beam system, if a typical VC inspection can achieve a throughput of m (e.g., area of sample inspected per unit time), then the method of the disclosed embodiments can increase the throughput to m X FA. As discussed above, in the disclosed embodiments, images of the sample do not need to be generated during inspection. Only the detected signal levels (e.g., corresponding to SEM image gray scale levels) of the specific SEM image pixels at points of interests need to be obtained. Similarly, in a multi-beam system, multiple electron beams may scan the points of interests simultaneously, which can further increase the throughput. Moreover, in multi-beam systems, each electron beam may have a partially independent deflection system so that each electron beam may be directed to a separate point of interest on the sample.

[0084] The disclosed embodiments provide more benefits than typical systems when migrating from a single beam system to a multi-beam system. For example, the throughput of a multi-beam system of the disclosed embodiments may be m X n X FAX FB, where n is the number of beams in the multibeam system. The efficiency factor FBmay be close to 1 if the beam grid formation and the scan actions of all the beams are properly arranged. In multi-beam systems of the disclosed embodiments, each beam needs at least a partially independent deflection system (e.g., not sharing the same deflection system) so that each beam can have at least partially independent scan actions. That is, each beam can scan and move different direction to reach their corresponding target instead of moving together synchronously, while still being synchronized with the detection system. In some embodiments, disclosed multi-beam systems may be a multi-column system such that each charged particle beam has at least a partially independent deflection system.

[0085] An additional advantage of the disclosed embodiments is that due to only a limited area on the sample being exposed to charged particles, the overall electron dose on the sample may be lower than in existing methods. In addition, due to only the points of interests being exposed to charged particles, sample charging or grounding issues may not be as severe as those in existing methods. This may also cause less damage to the sample. The signal to noise ratio (SNR) in the inspection can also be improved. To further improve the SNR, disclosed embodiments may increase the beam current during the charging phase or signal acquisition phase without charging issues. This enhanced SNR may further improve detection sensitivity and reduce false defect detection, thereby increasing throughput. This improvement may correspond to another efficiency factor Fcgreater than 1.

[0086] In disclosed embodiments, if the current single beam throughput is m, the overall throughput can be improved from m to up to: m X n X FAX FBX Fc. In some embodiments, the disclosed VC inspection method in a multi-beam, multi-column, or single beam environment may be used to improve VC inspections in production lines of the foundries research and development lines in the foundries.

[0087] A non-transitory computer readable medium may be provided that stores instructions for a processor of a controller (e.g., controller 109 of Fig. 1) for controlling the electron beam tool or other systems of other systems and servers, or components thereof, consistent with embodiments in the present disclosure. These instructions may allow the one or more processors to carry out image processing, data processing, beamlet scanning, graphical display, operations of a charged particle beam apparatus, or another imaging device, or the like for providing operations consistent with those described above for Fig. 5. In some embodiments, the non-transitory computer readable medium may be provided that stores instructions for a processor to perform the steps of process 500. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a Compact Disc Read Only Memory (CD-ROM), any other optical data storage medium, any physical medium with patterns of holes, a Random Access Memory (RAM), a Programmable Read Only Memory (PROM), and Erasable Programmable Read Only Memory (EPROM), a FLASH-EPROM or any other flash memory, Non-Volatile Random Access Memory (NVRAM), a cache, a register, any other memory chip or cartridge, and networked versions of the same.

[0088] The embodiments may further be described using the following clauses:1. A method for inspection of a sample, comprising: determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.2. The method of clause 1, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.3. The method of clause 1, wherein determining the plurality of locations on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining one or more patterns of the sample based on the generated image.4. The method of any one of clauses 1-3, further comprising aligning the sample with an inspection tool based on determined one or more patterns of features on the sample.5. The method of any one of clauses 1-4, wherein a location corresponding to an inspection feature comprises an area near the inspection feature.6. The method of any one of clauses 1-5, wherein a location corresponding to an inspection feature comprises the inspection feature.7. The method of any one of clauses 1-6, wherein the plurality of locations comprise an area less than an area of the FOV.8. The method of any one of clauses 1-7, further comprising adjusting a scan rate of the one or more charged particle beams such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.9. The method of any one of clauses 1-8, further comprising determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.10. The method of any one of clauses 1-9, further comprising modulating current of electron beamlets to adjust accumulated charges on an inspection feature.11. The method of any one of clauses 1-10, further comprising generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.12. The method of clause 11, further comprising analyzing the one or more signals.13. The method of any one of clauses 1-12, further comprising before providing the one or more charged particle beams to the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the plurality of locations.14. A method for inspection of a sample, comprising: determining a pattern of one or more inspection features on the sample in a field of view (FOV); charging the sample at one or more locations corresponding to the pattern of one or more inspection features; scanning the sample at one or more locations corresponding to the pattern of inspection features; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on detected one or more particle emissions.15. The method of clause 14, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.16. The method of clause 14, wherein determining the pattern of one or more inspection features on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining the pattern based on the generated image.17. The method of any one of clauses 14-16, further comprising aligning the sample with an inspection tool based on the determined pattern of one or more inspection features on the sample.18. The method of any one of clauses 14-17, wherein a location corresponding to the pattern of one or more inspection features comprises an area near the one or more inspection features.19. The method of any one of clauses 14-18, wherein a location corresponding to the one or more inspection features comprises the inspection feature.20. The method of any one of clauses 14-19, wherein the one or more locations comprise an area less than an area of the FOV.21. The method of any one of clauses 14-20, further comprising adjusting a scan rate of the scanning such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.22. The method of any one of clauses 14-21, further comprising determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.23. The method of any one of clauses 14-22, further comprising modulating current of electron beamlets to adjust accumulated charges on an inspection feature.24. The method of any one of clauses 14-23, further comprising generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.25. The method of clause 24, further comprising analyzing the one or more signals.26. The method of any one of clauses 14-25, further comprising before charging the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the one or more of locations.27. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for inspecting a sample, the operations comprising: determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.28. The non-transitory computer readable medium of clause 27, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.29. The non-transitory computer readable medium of clause 27, wherein determining the plurality of locations on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining one or more patterns of the sample based on the generated image.30. The non-transitory computer readable medium of any one of clauses 27-29, wherein the operations further comprise aligning the sample with an inspection tool based on determined one or more patterns of features on the sample.31. The non-transitory computer readable medium of any one of clauses 27-30, wherein a location corresponding to an inspection feature comprises an area near the inspection feature.32. The non-transitory computer readable medium of any one of clauses 27-31, wherein a location corresponding to an inspection feature comprises the inspection feature.33. The non-transitory computer readable medium of any one of clauses 27-32, wherein the plurality of locations comprise an area less than an area of the FOV.34. The non-transitory computer readable medium of any one of clauses 27-33, wherein the operations further comprise adjusting a scan rate of the one or more charged particle beams such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.35. The non-transitory computer readable medium of any one of clauses 27-34, wherein the operations further comprise determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.36. The non-transitory computer readable medium of any one of clauses 27-35, wherein the operations further comprise modulating current of electron beamlets to adjust accumulated charges on an inspection feature.37. The non-transitory computer readable medium of any one of clauses 27-36, wherein the operations further comprise generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.38. The non-transitory computer readable medium of clause 37, wherein the operations further comprise analyzing the one or more signals.39. The non-transitory computer readable medium of any one of clauses 27-38, wherein the operations further comprise before providing the one or more charged particle beams to the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the plurality of locations.40. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for inspecting a sample, the operations comprising: determining a pattern of one or more inspection features on the sample in a field of view (FOV); charging the sample at one or more locations corresponding to the pattern of one or more inspection features; scanning the sample at one or more locations corresponding to the pattern of inspection features;detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on detected one or more particle emissions.41. The non-transitory computer readable medium of clause 40, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.42. The non-transitory computer readable medium of clause 40, wherein determining the pattern of one or more inspection features on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining the pattern based on the generated image.43. The non-transitory computer readable medium of any one of clauses 40-42, wherein the operations further comprise aligning the sample with an inspection tool based on the determined pattern of one or more inspection features on the sample.44. The non-transitory computer readable medium of any one of clauses 40-43, wherein a location corresponding to the pattern of one or more inspection features comprises an area near the one or more inspection features.45. The non-transitory computer readable medium of any one of clauses 40-44, wherein a location corresponding to the one or more inspection features comprises the inspection feature.46. The non-transitory computer readable medium of any one of clauses 40-45, wherein the one or more locations comprise an area less than an area of the FOV.47. The non-transitory computer readable medium of any one of clauses 40-46, wherein the operations further comprise adjusting a scan rate of the scanning such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.48. The non-transitory computer readable medium of any one of clauses 40-47, wherein the operations further comprise determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.49. The non-transitory computer readable medium of any one of clauses 40-48, wherein the operations further comprise modulating current of electron beamlets to adjust accumulated charges on an inspection feature.50. The non-transitory computer readable medium of any one of clauses 40-49, wherein the operations further comprise generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.51. The non-transitory computer readable medium of clause 50, wherein the operations further comprise analyzing the one or more signals.52. The non-transitory computer readable medium of any one of clauses 40-51, wherein the operations further comprise before charging the sample: providing one or more light beams to thesample, each light beam being provided to adjust a charge of a corresponding location of the one or more of locations.53. A system to inspect a sample, the system comprising: a memory storing a set of instructions; and one or more processors configured to execute the set of instructions to cause the system to perform operations comprising: determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.54. The system of clause 53, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.55. The system of clause 53, wherein determining the plurality of locations on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining one or more patterns of the sample based on the generated image.56. The system of any one of clauses 53-55, wherein the operations further comprise aligning the sample with an inspection tool based on determined one or more patterns of features on the sample.57. The system of any one of clauses 53-56, wherein a location corresponding to an inspection feature comprises an area near the inspection feature.58. The system of any one of clauses 53-57, wherein a location corresponding to an inspection feature comprises the inspection feature.59. The system of any one of clauses 53-58, wherein the plurality of locations comprise an area less than an area of the FOV.60. The system of any one of clauses 53-59, wherein the operations further comprise adjusting a scan rate of the one or more charged particle beams such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.61. The system of any one of clauses 53-60, wherein the operations further comprise determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.62. The system of any one of clauses 53-61, wherein the operations further comprise modulating current of electron beamlets to adjust accumulated charges on an inspection feature.63. The system of any one of clauses 53-62, wherein the operations further comprise generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.64. The system of clause 63, wherein the operations further comprise analyzing the one or more signals.65. The system of any one of clauses 53-64, wherein the operations further comprise before providing the one or more charged particle beams to the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the plurality of locations.66. A system to inspect a sample, the system comprising: a memory storing a set of instructions; and one or more processors configured to execute the set of instructions to cause the system to perform operations comprising: determining a pattern of one or more inspection features on the sample in a field of view (FOV); charging the sample at one or more locations corresponding to the pattern of one or more inspection features; scanning the sample at one or more locations corresponding to the pattern of inspection features; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on detected one or more particle emissions.67. The system of clause 66, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.68. The system of clause 66, wherein determining the pattern of one or more inspection features on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining the pattern based on the generated image.69. The system of any one of clauses 66-68, wherein the operations further comprise aligning the sample with an inspection tool based on the determined pattern of one or more inspection features on the sample.70. The system of any one of clauses 66-60, wherein a location corresponding to the pattern of one or more inspection features comprises an area near the one or more inspection features.71. The system of any one of clauses 66-70, wherein a location corresponding to the one or more inspection features comprises the inspection feature.72. The system of any one of clauses 66-71, wherein the one or more locations comprise an area less than an area of the FOV.73. The system of any one of clauses 66-72, wherein the operations further comprise adjusting a scan rate of the scanning such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.74. The system of any one of clauses 66-73, wherein the operations further comprise determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.75. The system of any one of clauses 66-74, wherein the operations further comprise modulating current of electron beamlets to adjust accumulated charges on an inspection feature.76. The system of any one of clauses 66-75, wherein the operations further comprise generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.77. The system of clause 76, wherein the operations further comprise analyzing the one or more signals.78. The system of any one of clauses 66-77, wherein the operations further comprise before charging the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the one or more of locations.

[0089] It will be appreciated that the embodiments of the present disclosure are not limited to the exact construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

CLAIMS1. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for inspecting a sample, the operations comprising: determining a plurality of locations on the sample, each location corresponding to an inspection feature on the sample in a field of view (FOV); providing one or more charged particle beams to the sample, each charged particle beam being provided to a corresponding location of the plurality of locations; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on the one or more detected particle emissions.

2. The non-transitory computer readable medium of claim 1, wherein determining the plurality of locations on the sample is based on layout data of features on the sample.

3. The non-transitory computer readable medium of claim 1, wherein determining the plurality of locations on the sample comprises: scanning a portion of the sample; generating an image of the portion of the sample based on the scan; and determining one or more patterns of the sample based on the generated image.

4. The non-transitory computer readable medium of claim 1, wherein the operations further comprise aligning the sample with an inspection tool based on determined one or more patterns of features on the sample.

5. The non-transitory computer readable medium of claim 1, wherein a location corresponding to an inspection feature comprises an area near the inspection feature.

6. The non-transitory computer readable medium of claim 1, wherein a location corresponding to an inspection feature comprises the inspection feature.

7. The non-transitory computer readable medium of claim 1, wherein the plurality of locations comprise an area less than an area of the FOV.

8. The non-transitory computer readable medium of claim 1, wherein the operations further comprise adjusting a scan rate of the one or more charged particle beams such that a scan rate over an inspection feature is less than a scan rate over an area excluding the inspection feature.

9. The non-transitory computer readable medium of claim 1, wherein the operations further comprise determining that a corresponding inspection feature includes a defect when a generated signal is beyond a threshold.

10. The non-transitory computer readable medium of claim 1, wherein the operations further comprise modulating current of electron beamlets to adjust accumulated charges on an inspection feature.

11. The non-transitory computer readable medium of claim 1, wherein the operations further comprise generating one or more signals, each signal corresponding to a particle emission of the one or more particle emissions.

12. The non-transitory computer readable medium of claim 11, wherein the operations further comprise analyzing the one or more signals.

13. The non-transitory computer readable medium of claim 1, wherein the operations further comprise before providing the one or more charged particle beams to the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the plurality of locations.

14. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for inspecting a sample, the operations comprising: determining a pattern of one or more inspection features on the sample in a field of view (FOV); charging the sample at one or more locations corresponding to the pattern of one or more inspection features; scanning the sample at one or more locations corresponding to the pattern of inspection features; detecting, for each location, one or more particle emissions resulting from the charging of the corresponding location; and determining, for each location, defect information of the sample based on detected one or more particle emissions.

15. The non-transitory computer readable medium of claim 14, wherein the operations further comprise before charging the sample: providing one or more light beams to the sample, each light beam being provided to adjust a charge of a corresponding location of the one or more of locations.

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