Capacitance-Controlled Voltage Contrast Inspection in Charged Particle Beam Systems and Methods

Abstract

Systems and methods (400; 700) for detecting defects (638) in a sample (250) using a charged particle beam device are disclosed. A method (400; 700) for inspecting a sample (250) using a charged particle beam device comprises the steps of: causing a region of the sample (250) including a plurality of features (632) to be charged to a first polarity; causing the region to be switched from the first polarity to a second polarity under a switching condition—the switching condition includes the switching capacity of primary charged particles—; forming an inspection image of the region from signal charged particles generated upon interaction between the plurality of features (632) and the switching capacity of primary charged particles; and determining whether there is a defect in the feature (632) of the plurality of features (632) based on the gray level value of the feature (632) in the inspection image.

Description

Technology Field

[0001] This application claims priority to U.S. application 63 / 626,484 filed on January 29, 2024, the full text of which is incorporated herein by reference.

[0002] The embodiments provided herein disclose charged particle beam devices, in particular systems and methods for improving voltage contrast defect detection and defect classification. Background Technology

[0003] In the manufacturing processes of integrated circuits (ICs), incomplete or completed circuit components are inspected to ensure they are manufactured according to the design and are defect-free. Inspection systems utilizing optical microscopes or charged particle (e.g., electron) beam microscopes, such as scanning electron microscopes (SEM), may be adopted. As the complexity of device architectures increases, accurate inspection of 3D structures has become more critical. While voltage contrast inspection techniques may be adopted to detect physical or electrical defects embedded in these complex device structures, existing techniques suffer from issues such as low defect sensitivity, inability to detect high-resistance defects, or inaccurate defect type classification, which negatively impact defect capture rates, detection sensitivity, and inspection throughput.

[0004] One embodiment of the present invention relates to a method for detecting defects in a sample using a charged particle beam device. The method comprises the steps of: charging a region of a sample containing a plurality of features to a first polarity; switching the region from the first polarity to a second polarity under a switching condition—the switching condition includes a switching dosage of primary charged particles—forming an inspection image of the region from signal charged particles generated after the interaction of the plurality of features and the switching dosage of the primary charged particles; and determining whether there is a defect in a feature among the plurality of features based on the gray level value of the feature in the inspection image.

[0005] Another embodiment of the present invention relates to a method for inspecting a sample using a charged particle beam device. The method comprises the steps of: irradiating a region of a sample containing a plurality of features with a first primary charged particle capacity to charge the region with a first polarity; scanning the region with a plurality of scans of a second primary charged particle capacity to charge the region with a second polarity; forming a plurality of inspection images from signal charged particles generated after the interaction of the primary charged particles of each scan of the region and the plurality of scans; determining whether there is a defect in the features based on a comparison of gray level values ​​of the plurality of features in the inspection images of the plurality of inspection images; and, after determination, identifying the characteristics of the defect based on the inspection images and the corresponding primary charged particle capacity.

[0006] Another embodiment of the present invention relates to a charged particle beam device for sample inspection or defect detection. The device comprises a charged particle source configured to emit charged particles, the emitted charged particles form a primary charged particle beam, and the charged particle beam device is configured to cause a region of a sample including a plurality of features to be charged with a first polarity and, under a switching condition, cause the region to switch from the first polarity to a second polarity, wherein the switching condition includes a switching capacitance of the primary charged particles. The device further comprises a controller including a circuit configured to acquire an inspection image of the region from the signal charged particles generated upon interaction between the plurality of features and the switching capacitance of the primary charged particles, and to determine whether there is a defect in the feature based on the gray level value of the feature in the inspection image.

[0007] Another embodiment of the present invention relates to a charged particle beam device for sample inspection or defect detection. The device comprises a charged particle source configured to emit charged particles, wherein the emitted charged particles form a primary charged particle beam. The charged particle beam device is configured to cause a region of a sample comprising a plurality of features to be charged with a first polarity by irradiating the region with a first primary charged particle capacity, and to cause the region to be charged with a second polarity by scanning the region with a plurality of scans of a second primary charged particle capacity. The device further comprises a controller including a circuit configured to acquire a plurality of inspection images from signal charged particles generated after the interaction of the primary charged particles of each scan of the region and the plurality of scans, determine whether there is a defect in a feature based on a comparison of gray level values ​​of a plurality of features in the inspection images of the plurality of inspection images, and, after determination, identify the characteristics of the defect based on the inspection images and the corresponding primary charged particle capacity.

[0008] Another embodiment of the present invention relates to a non-transitory computer-readable medium storing a set of executable instructions to enable a charged particle beam device to perform a method of inspecting a sample by one or more processors of a charged particle beam device. The method comprises the steps of: activating a charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam—; irradiating a region of a sample containing a plurality of features using the primary charged particle beam to charge the region to a first polarity; irradiating the region using the primary charged particle beam to switch from the first polarity to a second polarity under a switching condition—the switching condition includes the switching capacitance of the primary charged particles—; forming an inspection image of the region from signal charged particles generated after the interaction of the plurality of features and the switching capacitance of the primary charged particles; and determining whether there is a defect in a feature among the plurality of features based on the gray level value of the feature in the inspection image.

[0009] Another embodiment of the present invention relates to a non-transient computer-readable medium that stores a set of executable instructions to enable a charged particle beam device to perform a method of inspecting a sample by one or more processors of a charged particle beam device. The above method comprises the steps of: activating a charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam—; irradiating a region of a sample containing a plurality of features using a first charged particle capacity of the primary charged particle beam to charge the region with a first polarity; scanning the region with a plurality of scans of a second charged particle capacity of the primary charged particle beam to charge the region with a second polarity; forming a plurality of inspection images from signal charged particles generated after the interaction of the primary charged particles of each scan of the region and the plurality of scans; determining whether there is a defect in a feature based on a comparison of gray level values ​​of a plurality of features in the inspection images of the plurality of inspection images; and, after determination, identifying the characteristics of the defect based on the inspection images and the corresponding primary charged particle capacity.

[0010] Other advantages of the embodiments of the present invention will become apparent from the following description taken together with the accompanying drawings, which describe the specified embodiments of the present invention in an illustrative and exemplary manner. Brief explanation of the drawing

[0011] FIG. 1 is a schematic diagram showing an exemplary electron beam inspection (EBI) system according to embodiments of the present invention. FIG. 2 is a schematic diagram showing an exemplary electron beam tool that may be part of the exemplary electron beam inspection system of FIG. 1, according to embodiments of the present invention. FIG. 3a is a schematic diagram showing a staircase structure of an exemplary 3D NAND memory device. FIG. 3b schematically illustrates defects in an exemplary multilayer structure and corresponding images observed using the electron beam inspection system of FIG. 1. Figure 3c schematically illustrates exemplary defects in a piping structure. FIG. 4a is a process flowchart of an exemplary method for sample inspection according to embodiments of the present invention. FIG. 4b schematically illustrates an exemplary methodology for defect detection used in sample inspection according to embodiments of the present invention. FIGS. 5A and FIGS. 5B schematically illustrate exemplary inspection images containing arrays of features. FIG. 6a schematically illustrates an exemplary methodology for defect detection used in sample inspection according to embodiments of the present invention. FIG. 6b shows a schematic representation of the number of defects detected for an applied capacity or acquired inspection image according to embodiments of the present invention. FIG. 6c schematically illustrates an exemplary inspection image including an array of features according to embodiments of the present invention. FIG. 7 is a process flowchart of an exemplary method for detecting defects according to embodiments of the present invention. Specific details for implementing the invention

[0012] Exemplary embodiments will now be described in detail, and such examples are illustrated in the drawings. The following description refers to the attached drawings, where the same numbers in different drawings represent identical or similar elements, unless otherwise indicated. The embodiments described in the following description of exemplary embodiments do not represent all embodiments conforming to the present invention. Instead, they are merely examples of apparatuses, systems, and methods conforming to embodiments related to the subject matter that may be mentioned in the appended claims. Without limiting the scope of the present invention, some embodiments may be described in relation to providing detection systems and detection methods in systems utilizing an electron beam (“e-beam”). However, the present invention is not so limited. Other types of charged particle beams (e.g., including protons, ions, muons, or any other particles carrying a charge) may be similarly applied. Additionally, other imaging systems such as optical imaging, photodetection, X-ray detection, extreme ultraviolet inspection, deep ultraviolet inspection, etc. may be used.

[0013] Electronic devices consist of circuits formed on a piece of silicon called a substrate. Semiconductor materials can include, for example, silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), or silicon germanium (SiGe). Many circuits can be formed together on the same part of silicon and are called integrated circuits, or ICs. With technological advancements, the size of these circuits has decreased dramatically, allowing more circuits to fit onto the substrate. For example, a smartphone IC chip can be as small as a fingernail and contain over 2 billion transistors, with each transistor being less than 1 / 1000 the width of a human hair.

[0014] Manufacturing these extremely small ICs is a complex, time-consuming, and costly process that often involves hundreds of individual steps. Even errors in a single step have the potential to induce defects in the finished IC, rendering it unusable. Therefore, one goal of the manufacturing process is to avoid these defects and maximize the number of functional ICs produced—that is, to improve the overall process yield.

[0015] One component of improving yield is monitoring the chip manufacturing process to ensure that it generates a sufficient number of functional integrated circuits. One way to monitor the process is to inspect chip circuit structures at the various stages of formation. Inspection can be performed using a scanning electron microscope (SEM). SEM is used to image these extremely small structures, effectively taking "photographs" of them. The images can be used to determine whether the structures have formed properly and in the correct locations. If a structure is defective, the process can be adjusted to minimize the likelihood of the defect recurring. Defects can occur during various stages of semiconductor processing. For the reasons mentioned above, it is important to detect defects accurately, efficiently, and as early as possible. To improve throughput (e.g., the number of samples processed per hour), it is desirable to perform inspections as quickly as possible.

[0016] The operating principle of a SEM is similar to that of a camera. A camera takes a picture by capturing and recording the brightness and color of light reflected or emitted from a person or object. A SEM takes a "picture" by capturing and recording the energy or amount of electrons reflected or emitted from structures. Before taking this "picture," an electron beam may be applied to the structures, and as electrons are reflected or emitted ("escape") from the structures, the SEM's detector can capture and record the energy or amount of those electrons to generate an image. To take this "picture," some SEMs use a single electron beam (called "single-beam SEM"), while others use multiple electron beams (called "multi-beam SEM") to take multiple "pictures" of a wafer. By using multiple electron beams, the SEM can provide more electron beams to the structures to obtain these multiple "pictures," causing more electrons to escape from the structures. Therefore, the detector can simultaneously receive more emitted electrons and generate images of wafer structures with higher efficiency and faster speed.

[0017] With continuous scaling and increased design and process complexity, the need for semiconductor manufacturing process control is growing. This need calls for advanced methods and more capable tools, as well as additional in-wafer, between-wafer, and lot-wide sampling to capture process variation and / or changes in process features. Integrated circuits (ICs) are expected to perform more complex tasks with higher efficiency and faster throughput at every new process technology node, which requires complex device architectures to accommodate higher-density active devices. In the context of the semiconductor device industry, a "technology node" (e.g., "10 nm") refers to the minimum size of a feature that can be reproducibly printed on a semiconductor wafer, such as the gate of a transistor or the half-pitch of a metal line.

[0018] In semiconductor devices, buried defects, such as voids or particles, can cause full open circuits and leakage (short circuits), or in some cases, partial open circuits or partial leakage. Conventional voltage contrast (VC) inspection techniques used to detect these defects involve flood exposure of negatively charged particles on the surface, such as electrons, and rely on differences in surface potential measurements of structures on the surface. The gray level of a pixel representing a surface region with a high surface potential is higher than the gray level of a pixel representing a region with a lower surface potential (appearing brighter in SEM images).

[0019] Conventional VC inspection or VC imaging techniques using electron beam devices such as SEMs operate in positive or negative voltage contrast modes. In either mode, features on the wafer under inspection [e.g., contact pad (340) in FIG. 3a] observed from above in the SEM device raise the electric potential by pre-charging the surface of the wafer with charged particles (e.g., electrons). Because they appear with different contrasts, floating and grounded conductors can be distinguished by visual inspection based on gray level values ​​accordingly. While conventional single-scan inspection techniques can be used to effectively determine the presence of defects, they may be unsuitable for determining the location of defects or classifying defects in stacked or laminated structures. In other words, while conventional VC inspection techniques can distinguish between defective and non-defective features, they may not be used for further defect classification, such as distinguishing between hard electrical open circuits and high-resistance defects. High-resistance defects do not generate many signal electrons, making them more difficult to detect by conventional single-scan VC inspection techniques. Although the sensitivity for detecting high-resistance defects is maximum in neutral mode, conventional inspection techniques are very unstable under neutral conditions.

[0020] Some embodiments of the present invention relate to apparatuses and methods for detecting defects in a sample by voltage contrast inspection. The method may include the step of pre-charging a sample to a first polarity using a beam of charged particles having a high average beam current. The polarity of the sample may be switched from the first polarity to a second polarity opposite to the first polarity under switching conditions by applying an incremental charged particle capacitance. The method may further include the step of acquiring an inspection image at each applied capacitance of the incremental capacitance, performing defect detection on each acquired image, and determining the presence of a defect based on the gray level value of a feature within the inspection image under switching conditions.

[0021] In the drawings, the relative dimensions of the components may be exaggerated for clarity. In the following description of the drawings, identical or similar reference numbers refer to identical or similar components or objects, and only differences in individual embodiments are described. As used herein, unless specifically stated otherwise, the term “or” includes all possible combinations except where impractical. For example, if it is stated that a component may include A or B, the component may include A, or B, or A and B, unless specifically stated otherwise or impractical otherwise. As a second example, if it is stated that a component may include A, B, or C, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C.

[0022] Now, referring to FIG. 1, which illustrates an exemplary electron beam inspection (EBI) system (100) according to embodiments of the present invention. As shown in FIG. 1, the charged particle beam inspection system (100) comprises a main chamber (10), a load-lock chamber (20), an electron beam tool (40), and an EFEM (equipment front end module: 30). The electron beam tool (40) is located within the main chamber (10). It is understood that while the description and drawings relate to electron beams, the embodiments are not intended to limit the present invention to specific charged particles.

[0023] The EFEM (30) includes a first loading port (30a) and a second loading port (30b). The EFEM (30) may include additional loading port(s). The first loading port (30a) and the second loading port (30b) receive wafer FOUPs (front opening unified pods) containing wafers to be inspected [e.g., semiconductor wafers or wafers made of other materials] or samples (hereinafter, wafers and samples are collectively referred to as "wafers"). One or more robot arms (not shown) within the EFEM (30) transfer the wafers to a load lock chamber (20).

[0024] The load lock chamber (20) is connected to a load / lock vacuum pump system (not shown) that removes gas molecules within the load lock chamber (20) to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robot arms (not shown) transfer the wafer from the load lock chamber (20) to the main chamber (10). The main chamber (10) is connected to a main chamber vacuum pump system (not shown) that removes gas molecules within the main chamber (10) to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is inspected by an electron beam tool (40). In some embodiments, the electron beam tool (40) may include a single-beam inspection tool. In other embodiments, the electron beam tool (40) may include a multi-beam inspection tool.

[0025] The controller (50) may be electronically connected to the electron beam tool (40) and may also be electronically connected to other components. The controller (50) may be a computer configured to perform various controls of the charged particle beam inspection system (100). Additionally, the controller (50) may include a processing circuit configured to perform various signal and image processing functions. Although the controller (50) is depicted in FIG. 1 as being outside the structure including the main chamber (10), load lock chamber (20), and EFEM (30), it is understood that the controller (50) may be part of the structure.

[0026] In some embodiments, the controller (50) may include one or more processors (not shown). A processor may be a general or specific electronic device capable of manipulating or processing information. For example, a processor may include any number of central processing units (or “CPU”), graphics processing units (or “GPU”), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLA), programmable array logic (PAL), general array logic (GAL), complex programmable logic devices (CPLD), field programmable gate arrays (FPGA), system-on-chip (SoC), application-specific integrated circuits (ASIC), neural network processing units (NPU), and any combination of any type of circuit capable of data processing. Additionally, a processor may be a virtual processor comprising one or more processors distributed across multiple machines or devices coupled through a network.

[0027] The present invention provides examples of a main chamber (10) housing an electron beam inspection system, but it should be noted that the embodiments of the present invention are not limited to a chamber housing an electron beam inspection system in the broadest sense. Rather, it is understood that the foregoing principles may be applied to other chambers.

[0028] Now, referring to FIG. 2, which shows a schematic diagram illustrating an exemplary configuration of an electron beam tool (40) that may be part of the exemplary charged particle beam inspection system (100) of FIG. 1 according to embodiments of the present invention. The electron beam tool (40) [also referred to herein as device (40)] may include an electron emitter, which may include a cathode (203), an extractor electrode (205), a gun aperture (220), and an anode (222). The electron beam tool (40) may further include a Coulomb aperture array (224), a focusing lens (226), a beam-limiting aperture array (235), an objective lens assembly (232), and an electron detector (244). The electron beam tool (40) may further include a sample holder (236) supported by a motorized stage (234) to hold the sample (250) to be inspected. It should be understood that other related components may be added or omitted as needed.

[0029] In some embodiments, the electron emitter may include a cathode (203) and an anode (222), and primary electrons may be emitted from the cathode and extracted or accelerated to form a primary electron beam (204) that forms a primary beam crossover (202). The primary electron beam (204) may be visualized as being emitted from the primary beam crossover (202).

[0030] In some embodiments, the electron emitter, focusing lens (226), objective lens assembly (232), beam-limiting aperture array (235), and electron detector (244) may be aligned with the primary optical axis (201) of the device (40). In some embodiments, the electron detector (244) may be positioned off the primary optical axis (201) and along a secondary optical axis (not shown).

[0031] In some embodiments, the objective lens assembly (232) may include a modified SORIL (swing objective retarding immersion lens), which includes a pole piece (232a), a control electrode (232b), a beam manipulator assembly including deflectors (240a, 240b, 240d, and 240e), and an exciting coil (232d). In a typical imaging process, a primary electron beam (204) emanating from the tip of the cathode (203) is accelerated by an acceleration voltage applied to the anode (222). A portion of the primary electron beam (204) passes through the apertures of the gun aperture (220) and the Coulomb aperture array (224), and is focused by a focusing lens (226) to pass completely or partially through the apertures of the beam-limiting aperture array (235). Electrons passing through the aperture of the beam-limited aperture array (235) can be focused by a modified SORIL lens to form a probe spot on the surface of the sample (250) and deflected by one or more deflectors of the beam manipulator assembly to scan the surface of the sample (250). Secondary electrons emanating from the sample surface can be collected by an electron detector (244) to form an image of the scanned region of interest.

[0032] In the objective lens assembly (232), the excitation coil (232d) and the electrode (232a) can generate a magnetic field. A portion of the sample (250) being scanned by the primary electron beam (204) can be immersed in the magnetic field and electrically charged, which in turn generates an electric field. The electric field can reduce the energy of the primary electron beam (204) colliding with the surface of the sample (250) and near it. A control electrode (232b), which is electrically insulated from the electrode (232a), can, for example, control the sample (250) and the electric field above it to reduce aberrations of the objective lens assembly (232), control the focusing situation of the signal electron beams for high detection efficiency, or protect the sample by preventing arcing. One or more deflectors of the beam manipulator assembly can deflect the primary electron beam (204) to facilitate beam scanning on the sample (250). For example, in the scanning process, the deflectors (240a, 240b, 240d, and 240e) may be controlled to deflect the primary electron beam (204) onto different locations on the top surface of the sample (250) at different times to provide data for image reconstruction of different parts of the sample (250). It should be noted that the order of 240a through 240e may differ in different embodiments.

[0033] When receiving a primary electron beam (204), backscattered electrons (BSEs) and secondary electrons (SEs) may be emitted from a portion of the sample (250). A beam splitter may direct the secondary or scattered electron beam(s), including the backscattered and secondary electrons, toward the sensor surface of an electron detector (244). The detected secondary electron beams may form corresponding beam spots on the sensor surface of the electron detector (244). The electron detector (244) may generate signals (e.g., voltages, currents) indicating the intensities of the received secondary electron beam spots and provide the signals to a processing system such as a controller (50). The intensities of the secondary or backscattered electron beams and the resulting secondary electron beam spots may vary depending on the external or internal structure of the sample (250). In addition, as previously discussed, the primary electron beam (204) can be deflected onto different locations on the top surface of the sample (250) to generate secondary or scattered electron beams (and resulting beam spots) of different intensities. Therefore, by mapping the intensities of the secondary electron beam spots to locations on the sample (250), the processing system can reconstruct an image reflecting internal or external structures of the wafer sample (250).

[0034] In some embodiments, the controller (50) may include an image processing system comprising an image acquirer (not shown) and a storage (not shown). The image acquirer may include one or more processors. For example, the image acquirer may include a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, or a combination thereof. The image acquirer may be connected to an electronic detector (244) of the device (40) via a medium such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the Internet, a wireless network, a wireless radio, or a combination thereof. In some embodiments, the image acquirer may receive a signal from the electronic detector (244) and construct an image. Accordingly, the image acquirer may acquire images of regions of the sample (250). Additionally, the image acquirer may perform various post-processing functions, such as generating contours and superimposing markers on the acquired images. The image acquirer may be configured to perform adjustments, such as brightness and contrast, of the acquired images. In some embodiments, the storage may be a storage medium such as a hard disk, a flash drive, cloud storage, RAM (random access memory), or other types of computer-readable memory. The storage may be coupled with an image acquirer and may be used to store scanned raw image data as original images and post-processed images.

[0035] In some embodiments, the controller (50) may include measurement circuits (e.g., analog-to-digital converters) to obtain the distribution of detected secondary electrons and backscattered electrons. The electron distribution data collected during the detection time window may be used to reconstruct images of the wafer structures under inspection by combining the corresponding scan path data of the primary beam (204) incident on the surface of the sample (e.g., wafer). The reconstructed images may be used to reveal various features of the internal or external structures of the sample (250), thereby revealing any defects that may be present in the wafer.

[0036] In some embodiments, the controller (50) may control the motorized stage (234) to move the sample (250) during inspection. In some embodiments, the controller (50) may allow the motorized stage (234) to continuously move the sample (250) in one direction at a constant speed. In other embodiments, the controller (50) may allow the motorized stage (234) to change the speed of movement of the sample (250) over time according to the steps of the scanning process.

[0037] As is generally known in the art, interactions between charged particles, such as electrons in a primary electron beam, and a sample can generate signal electrons containing compositional and topographical information regarding the probe regions of the sample. Secondary electrons (SEs) can be identified as signal electrons with low emission energies, and backscattered electrons (BSEs) can be identified as signal electrons with higher emission energies. Due to their low emission energies, the objective lens assembly can orient the SEs along electron paths and focus them onto the detection surface of an in-lens electron detector positioned within the SEM column. BSEs traveling along electron paths can also be detected by the in-lens electron detector. However, in some cases, BSEs with large emission angles may not be detected using additional electron detectors, such as backscattered electron detectors, or may not be detected at all, leading to a loss of sample information necessary for sample inspection or critical dimension measurements.

[0038] Detection and inspection of some defects in semiconductor manufacturing processes, such as particles embedded during photolithography, metal deposition, dry etching, or wet etching, can benefit from the inspection of surface features and the analysis of the composition of defect particles. In these scenarios, information obtained from secondary electron detectors and backscattered electron detectors may be desirable to the user for identifying defect(s), analyzing the composition of defect(s), and adjusting process parameters based on the obtained information.

[0039] Now, referring to FIG. 3a, which illustrates a schematic diagram of an exemplary memory device (300) having a “step-like” structure. The device (300) may include a plurality of memory cells stacked vertically on a substrate (310). The device (300) may be fabricated by depositing a plurality of alternating layers of dielectric materials, such as oxide and nitride films (325), for example. The memory device (300) may include horizontal word-lines (302), which may be formed by removing sacrificial layers, such as nitride films, from the stack and then refilling them with a conductive material such as tungsten. The formation of memory cells within the device (300) may further include step-like etching of pairs of dielectric films and metal filling of contact channels (330), including contact pads (340) for connecting bit-line bus contacts (not shown in FIG. 3a) to the word-lines. To provide an "up and down" shape of the WL steps used in 3D NAND devices, multiple wordline lithography steps may be performed with repeated vertical step etching and 2D trimming at each step. These series of process steps require precise etching step profiling for the WL contacts, trimming etching uniformity, and pull-back CD control. The length of the WL steps may be increased as more memory cells are stacked vertically to improve efficiency, storage density, etc. The device (300) may include a film stack that is thicker than 64 layers, thicker than 96 layers, or in some cases even thicker than 124 layers. Through the entire film stack, vertical channel holes (not shown) may be further created by high aspect ratio (HAR) etching. In some cases, the HAR may be greater than 100:1. Individual memory cells within the layers can be electrically connected through word-line replacement metal fillings provided by materials such as tungsten, for example.Word-line metal filling can involve void-free filling of complex and narrow lateral structures with minimal stress on the device stack. In practice, fabricating 3D NAND devices is very difficult, and it may be desirable to detect physical or electrical defects that occur during or after the fabrication of these complex device structures.

[0040] It can be difficult to detect buried defects in vertical high-density structures such as 3D NAND flash memory devices (300). One of the various ways to detect buried or surface-level electrical defects in these devices is to use voltage contrast methods in SEM. In this method, differences in electrical conductivity of the material, structure, or region of the sample cause contrast differences in SEM images. In the context of defect detection, since electrical defects beneath the sample surface can cause charge fluctuations on the sample surface, electrical defects can be detected by contrast in SEM images of the sample surface. To enhance voltage contrast, a process called pre-charging or flooding may be adopted, where the region of interest of the sample uses a small beam current but can be exposed to a large beam current prior to inspection with high imaging resolution. Regarding inspection, some of the benefits of flooding may include reducing the charge on the wafer to minimize image distortion caused by charge, and in some cases, increasing the charge on the wafer to enhance the difference between defective features and surrounding defect-free features in the image. Some inspection systems, such as SEMs, are equipped to detect wafer defects using voltage contrast methods and can operate in multiple modes, such as a flooding mode to highlight defects followed by an inspection mode to detect defects. In the flooding mode, to increase voltage contrast, it may be desirable to maximize the beam current of the primary electron beam irradiating the sample so that the maximum number of electrons pass through the aperture. However, in the inspection mode, a small probe spot with a small beam current may be desirable for high-resolution imaging.

[0041] In semiconductor devices, buried defects such as voids can cause full or hard open circuits, while the presence of high-resistance defects and unwanted particles can cause leakage (short circuits) or, in some cases, partial open circuits or partial leakage. Conventional voltage contrast (VC) inspection techniques used to detect these defects involve flood exposure of negatively charged particles, such as electrons, on a surface and rely on differences in surface potential measurements of structures on the surface. The gray level of a pixel representing a surface region with a high surface potential is higher than the gray level of a pixel representing a region with a lower surface potential (appearing brighter in SEM images). The gray levels of the structures are compared to a reference gray level to detect defects.

[0042] Defect detection is a critical aspect of semiconductor device manufacturing. Early detection, preferably across multiple manufacturing stages, allows the causes of defects to be identified and eliminated before they affect many wafers. In some cases, VC inspection techniques such as passive voltage contrast, bias voltage contrast, capacitive coupling voltage contrast, or electron beam probing may be used for failure analysis, but are not limited thereto. Conventional VC inspection or VC imaging techniques using electron beam devices, such as SEMs, operate in positive or negative voltage contrast modes. In either mode, features on the wafer under inspection [e.g., contact pad (340) in FIG. 3a] observed from above in the SEM device raise the electric potential by pre-charging the surface of the wafer with charged particles (e.g., electrons). Because they appear with different contrasts, floating and grounded conductors can be distinguished accordingly by visual inspection. An example of a floating conductor or electrical open circuit (305) and an example of a high-resistance fault (308) are shown in FIG. 3b. For comparison, an example of a grounded conductor [e.g., a contact channel (330)] is also shown in FIG. 3b.

[0043] In the positive voltage contrast mode, the floating conductor is charged with a voltage that is more positive than that of the grounded conductor. However, in the negative voltage contrast mode, the floating conductor is charged with a voltage that is more negative than that of the grounded conductor. In the positive voltage contrast mode, as shown in the exemplary secondary electron images of FIG. 3b, electrically isolated structures, e.g., unconnected gate contacts, can be positively charged because the emitted secondary electrons cannot be compensated. The isolated structures may appear dark in the secondary electron image because some of the emitted electrons may not reach the secondary electron detector due to the decelerating electric field near the surface [e.g., feature 305A corresponds to the electrical open (305)]. On the other hand, the grounded structure [e.g., the contact channel (330) electrically connected to the word-line (320)] is not charged and may appear brighter in the secondary electron image due to a higher secondary electron yield and more detectable emitted electrons. In negative voltage contrast mode, electrical hard open circuits may appear bright in the secondary electronic image, and grounded features may appear darker.

[0044] Referring to FIG. 3b, it further illustrates a schematic representation of the gray level value signals of contacts for a defect-free word-line and a defect word-line upon the application of a charged particle capacitance according to embodiments of the present invention. In FIG. 3b, image features 305A and 308A represent the gray level value signals of a defect feature (hard open and high-resistance defects, respectively), and image feature 325A represents the gray level value signal of a defect-free feature. In this context, a "defect-free" feature refers to a feature, structure, or device that does not have or is not associated with physical or electrical defects. In some cases, physical defects, such as insufficient etching of a metal line or excessive etching of a dielectric film, can induce electrical defects. In this context, a "defective" feature refers to a feature, structure, or device that has or is associated with one or more physical or electrical defects. An example of a defective feature may include a structure that fails to form a desired electrical connection with the underlying structure. As used herein, the gray level value of a feature refers to the grayscale level of the feature observed in an image (e.g., an SEM image). As an example, an 8-bit grayscale image may have 256 discrete grayscale levels, and each pixel may be assigned a grayscale value between "0" and "255", where gray level 0 represents a dark pixel and gray level 255 represents a bright pixel. In the context of the present invention, "dosage" refers to the total number of charged particles to which the feature may be exposed. In some embodiments, the charged particles may include electrons, for example, in an SEM. If the dosage includes electrons, the dosage may be expressed as the total number of electrons or the total charge carried by the total number of electrons (in Coulombs). The charge of an electron is 1.6 x 10⁻¹⁰ -19It must be understood that it can be a Coulomb. For example, the capacitance of charged particles can be applied by applying a voltage signal configured to supply a desired number of charges or charged particles to the contact.

[0045] As previously described, existing (VC) inspection techniques involve performing high-capacity (i.e., high beam current) pre-scan flooding or charging of a sample region of interest, followed by performing a low-capacity inspection scan to detect signal electrons generated from features on the sample. The low-capacity inspection scan may be a positive mode scan or a negative mode scan. In either case, the inspection technique includes a single inspection scan. While existing single-scan inspection techniques can be used to effectively determine the presence of defects, they may be unsuitable for determining the location of defects or classifying defects in stacked or laminated structures. In other words, while existing VC inspection techniques can distinguish between defective and non-defective features, they may not be used for further defect classification, such as distinguishing between hard electrical open circuits and high-resistance defects.

[0046] FIG. 3c schematically illustrates an exemplary logic device structure (370) including examples of electrical open or high-resistance defects. In the context of the invention, a high-resistance defect refers to a partially open electrical defect having a resistance of 1 MΩ (megaohm) or more. The structure (370) may include, but is not limited to, a plurality of metal layers (M2, M3, or M4) interconnected through one or more vias (V1, V2, or V3). One or more physical or electrical defects (305_1, 305_2, or 305_3) may occur during the fabrication of the structure (370). Defect 305_1 represents an "unlanding" defect or electrical open where the conductive via V3 fails to form electrical continuity between metal M4 and metal M3. Defect 305_2 represents a "single line open" (SLO) defect causing an electrical discontinuity within metal M3. Defect 305_3 represents another unlanding defect where the conductive via V2 fails to form an electrical continuity between metal M3 and metal M2. Typically, in conventional VC inspection techniques, a pre-charge capacitance can be set based on the highest value to capture all defects. While this approach can efficiently capture most defects, further classification of defects, including defect type or location relative to a reference feature, may be impossible. In this example, each defect (305_1, 305_2, and 305_3) may appear as a dark feature (electrical open or defective) without further classification of defect type or location. Therefore, it may be desirable to provide voltage contrast inspection systems and methods that detect and classify electrical defects based on applied charge particle capacitance.

[0047] Now, referring to FIG. 4a, which is a process flowchart illustrating an exemplary method (400) of sample inspection for defect detection using a charged particle beam device according to embodiments of the present invention. One or more steps of the method (400) may be performed by a controller (50) of an EBI system (100) as shown in FIG. 2, for example. Here, the controller (50) may instruct a module of the charged particle beam device to activate a charged particle source to generate a primary charged particle beam (e.g., an electron beam), apply an incremental capacity of charged particles to a region of interest of a sample [e.g., sample (250) in FIG. 2], acquire an inspection image based on detected signal charged particles generated from the sample, or perform other related functions.

[0048] In step 410, a charged particle source of a charged particle beam device, such as a SEM, is activated to emit charged particles (e.g., electrons). The charged particles can form a charged particle beam [e.g., the primary charged particle beam (204) in FIG. 2]. The electron source can be activated by a controller [e.g., the controller (50) in FIG. 2]. For example, the electron source can be controlled to emit primary electrons to form an electron beam along a primary optical axis [e.g., the primary optical axis (201) in FIG. 2]. The electron source can be activated remotely, for example, by software, an application, or a processor of the controller using a set of instructions to power the electron source through a control circuit. The primary electron beam can pass through a Coulomb aperture array [e.g., Coulomb aperture array (224) in FIG. 2] and a beam-limiting aperture array (not shown) to adjust the beam size or beam current of the primary electron beam and form a probing beam incident on a sample [e.g., sample (250) in FIG. 2].

[0049] Additionally, in step 410, the region of interest (ROI) of the sample is irradiated with incremental charge particle doses from a primary charge particle beam. The ROI may include multiple features, such as contacts or contact pads [e.g., contact pads (340) in FIG. 3a] for multiple word lines [e.g., word lines (320) in FIG. 3a]. Irradiating the ROI with charge particles involves irradiating each feature of interest within the region of interest with a first dose of charge particles, such as electrons from a primary electron beam of a SEM tool. Irradiating the features of interest may enable the identification of defects based on stored charges, which forms a gray level value contrast signal of the features in an acquired image, such as a SEM image. The primary charge particle beam may be a high-dose electron beam configured to inspect the sample for defects. As used herein, the high-dose electron beam comprises a primary electron beam having a high average beam current. In some embodiments, the average beam current may be in the range of 100 nA to 500 nA, or 200 nA to 500 nA, or 300 nA to 500 nA, or 400 nA to 500 nA. In some embodiments, the average beam current of the high-capacity electron beam may be higher as needed. The high-capacity electron beam may function as a probing or inspection beam, as well as a flooding or pre-scanning beam.

[0050] "Incremental capacity" as used herein refers to a gradual increase in the charged particle capacity applied through the irradiation of a charged particle beam onto the surface of a sample for multi-scan inspection. In such cases, when an ROI is scanned "n" times by the charged particle beam—where n is a positive integer and n ≥ 2—the capacity for the n-th scan (D n ) is the capacity (D) for the (n-1)-th scan n-1It is higher than ) by a known coefficient. In some embodiments, the capacitance on the substrate (e.g., wafer) is fixed and can be accumulated over multiple scans. For example, if the capacitance on the substrate for the first scan is D1, the accumulated capacitance on the substrate after the second scan may be twice the capacitance for the first scan, expressed mathematically as (D2) = 2*(D1), or the accumulated capacitance on the substrate after the third scan may be the sum of the capacitances for the first, second, and third scans (D3 = D1 + D2 + D3), or the accumulated capacitance on the substrate after the fourth scan may be the sum of the capacitances for the first, second, third, and fourth scans (D4 = D1 + D2 + D3 + D4), and so on.

[0051] In some embodiments, there may be substantially no time delay between consecutive scans in a multi-scan inspection. In some embodiments, the time delay between consecutive scans may be negligible, on the order of a few microseconds or less. For example, if the scanning frequency for the ROI is 1 Hertz (Hz) and the time delay is 100 microseconds (µs), the total time required to scan the ROI 10 times may be 10.0009 seconds, which adds 900 µs to the total scan time. In some embodiments, the time delay may be adjusted based on factors including—but not limited to—the charge-discharge rate of the features, the size of the ROI, the number of defects, the location of the defects, the type of defects, etc. In some embodiments, the capacities (D1, D2, and D3) may be the same (D1 = D2 = D3), in which case the capacities (D4) for the fourth scan may be equal to three times the capacities for the first scan (D4 = 3*D1). In some embodiments, the capacities increments (D1, D2-D1, and D3-D2) may be different, in which case D4 = D1 + D2 + D3. In some embodiments, the capacities (D4) for the fourth scan may be greater than the sum of the previous capacities (D1, D2, and D3) (D4 > D1 + D2 + D3). Although only the capacities for four scans are discussed above, it should be understood that there may be fewer or more scans as needed.

[0052] In step 420, as shown in FIG. 4b, inspection images of the region of interest (ROI) corresponding to each applied capacity of the incremental capacities may be obtained. The inspection images (452, 453, 454, 455, and 460) (also referred to herein as frames) correspond to each of the applied capacities (D1, D2, D3, D4, and D nIt corresponds to ). Since the capacity is maintained across each individual scan of the ROI, each inspection image or each frame corresponds to one scan. For example, the 5th frame may correspond to the 5th scan of the charged particle capacity (D5), where D5 = D4 + D3 + D2 + D1. The inspection images (e.g., inspection images 452, 453, 454, 455, or 460) may include SEM inspection images formed based on signal particles (e.g., secondary electrons, backscattered electrons, etc.) generated during the interaction of features within the ROI and charged particles. The acquired images may be stored in a database to allow for comparison and retrieval for defect inspection in subsequent stages.

[0053] In step 430 of FIG. 4a, defect detection may be performed for each inspection image to generate corresponding defect features for each acquired inspection image. Performing defect detection may include, but is not limited to, performing die-to-die comparisons, or performing cell-to-cell comparisons, or performing die-to-database pixel analysis. As used herein, "defect signature" refers to a spatial pattern or map of defects identified in a sample. A defect signature may be used as an identification characteristic of the sample.

[0054] In die-to-die mode, inspection images of two or more dies can be compared to detect defects within the inspection images. For example, multi-scan inspection of a sample containing multiple dies may involve acquiring 25 frames of each die on a wafer, and defects may be identified within each frame for all dies. In this scenario, for example, the 20th frame for all dies may be compared to identify defects. The comparison of frames or inspection images may include, for example, visual inspection to identify defects based on the gray level values ​​of features.

[0055] In cell-to-cell mode, defect detection may be based on the locations of features within a repeating unit of a cell or die. For example, multi-scan inspection of an ROI containing cells may involve acquiring multiple images of the cells. In an inspection image of a cell containing multiple arranged features, the presence of a feature at an unintended location or the absence of a feature at an expected location of the arrangement may indicate the presence of a defect. The intended or expected location may be based on the characteristics of the arranged pattern of features within the cell or other similar cells.

[0056] In die-to-database pixel counting mode, an inspection image of the die can be compared with a reference image or reference layout of the die. The reference image or reference layout may be a database image or a reference feature layout. Reference feature information may be obtained from an information file containing a wafer design layout in a Graphic Database System (GDS) format, Graphic Database System II format, or Open Artwork System Interchange Standard (OASIS) format, which contains a graphic representation of features on the wafer surface. The feature layout may be based on a pattern layout for configuring devices on the wafer. The wafer design layout may correspond to one or more photolithography masks or reticles used to transfer features from the photolithography mask or reticle to the wafer. The GDS information file or OASIS information file may contain feature information stored in a binary file format representing planar geometric shapes, text, and other information related to the wafer design layout.

[0057] Additionally, in step 430, data associated with all frames may be merged, and defects that are repeated across different frames may be identified as defects along with a label. The label may further include data indicating the frame containing the defect or the frames. In some embodiments, the merged data may be a spatial map of defects, or may be presented in a tabular format or any other suitable format.

[0058] In step 440, the identified defect(s) may be classified based on the characteristics of the defect. The defect classification may include, but is not limited to, hard open, high-resistance defect, partial open, short, partial leakage, or blinking defect. As used herein, a blinking defect refers to an electrical defect that may appear or disappear between frames. As one example, a blinking defect may appear in a second frame but disappear in a third frame or any subsequent frame. In some cases, though not necessarily, the defect may reappear in a subsequent frame and exhibit "blinking" characteristics. As another example, a blinking defect may appear in a first frame, disappear in the next frame, and then reappear in a subsequent frame where higher capacitance charged particles are applied. A blinking defect may be caused by a sudden breakdown of insulation of a feature. A feature may be slowly charged by exposing it to irradiation with charged particles, but may no longer retain charge due to dielectric breakdown, for example, and discharge may be rapid. If the breakdown is not catastrophic, the feature may be recharged with a higher capacity applied in a subsequent stage, but a similar failure mode may reappear and appear as a "bling" defect. FIG. 4b shows an exemplary bling defect (472) that first appears in inspection image 454, disappears in inspection image 455, and reappears in inspection image 460. The dashed circle (472M) indicates the absence of the defect (472) from its original location identified in inspection image (454) [to be used only as a visual aid to indicate the expected location of the defect (472)].

[0059] Defect identification and detection in existing VC inspection technologies may be unsuitable for consistently capturing blinking defects because defects are identified based on visual inspection differences between two frames and other frames are excluded from inspection. However, in the proposed sample inspection method, the output data includes information associated with each inspection image, and defect detection is performed on each inspection image. Defects are identified and classified based on a comparison of defect features from each inspection image, thereby significantly improving the defect capture rate.

[0060] In some embodiments, the characteristics of the defect are the time of appearance of the defect, or the frame in which the defect first appears, or the critical capacity (D) that causes the defect to appear in the frame. t It may include ), or the invariance of the defect, or the blinking period of the defect, etc. Critical capacity (D as used herein) t ) refers to the minimum dose of charged particles irradiated onto a sample to detect a defect in an inspection image. In some embodiments, the time of appearance of the defect in the image or the frame in which the defect first appears may be used to determine the threshold dose. As schematically illustrated in FIG. 4b, the number of detected defects may increase with increasing applied dose. Thus, the number of defects detected in the inspection image (455) corresponding to dose D4 may be greater than the number of defects detected in inspection images D3, D2, or D1, because D4 > D3 > D2 > D1. In other words, the threshold dose for defect detection may be based on data associated with the inspection image in which the defect first appears.

[0061] In some embodiments, critical capacity (D t) may be based on the defect type, or defect location, or detection sensitivity of the charged particle detector, etc. In some embodiments, the threshold capacity may be determined based on the capacitance of features associated with the defect. As one example, referring to the structure (370) of FIG. 3c, since the capacitance associated with V3 and M4 is smaller than the capacitance associated with V3, M4 and M3, the detection capacity applied to detect defect 305_1 may be smaller than the detection capacity applied to detect defect 305_2. As another example, the detection capacity for detecting defect 305_3, which is an electrical open between V2 and M2, is higher than the detection capacity for 305_1 and 305_2, so the threshold capacity (D t It is possible to identify the location of defects within the structure based on information related to the capacitance of ) or associated features.

[0062] In some embodiments, defect characteristics may include defect invariance or blinking period. If a defect appears consistently in each frame of a plurality of frames obtained, the defect may be a fixed defect. If the defect is a blinking defect such as blinking defect 472, the blinking period of the blinking defect (472) may be determined based on the time difference between the first appearance and the second appearance. Time information may be obtained based on the scan rate, scan frequency, or time delay between scans.

[0063] High-resistance defects, such as the defect (308) shown in FIG. 3b, typically do not generate many signal electrons, making them more difficult to detect by conventional single-scan VC inspection techniques. This is because thin resistive layers (e.g., oxide) that remain or are partially destroyed during inspection scanning provide tunneling paths for electrons, leading to low detection sensitivity. In negative mode or positive mode VC inspection, the voltage contrast difference between a defect-free feature [e.g., the contact channel (330) in FIG. 3b] and a defective feature [e.g., the contact channel (318) with the high-resistance defect (308)] is low, as shown in the corresponding feature images (325A and 308A), respectively. Therefore, it may be desirable to provide systems and methods that improve detection sensitivity for high-resistance defects by increasing the signal intensity difference between a defect-free feature and a defective feature.

[0064] Now, referring to FIGS. 5a and 5b, which schematically illustrate exemplary inspection images (510 and 520) of an ROI in a single positive mode scan and a single negative mode scan, respectively. Exemplary inspection image 510 represents a uniform feature array detected using a single positive mode scan VC inspection technique, and inspection image 520 represents a uniform feature array detected using a single negative mode scan VC inspection technique. In either mode, the ROI may be flooded with high-capacity charged particles to enhance voltage contrast signals by pre-scanning the ROI surface. Features 512 and 522 represent normal contacts or defect-free features in the inspection images (510 and 520), respectively. Features 518 and 528 represent defective features (e.g., high-resistance defects) in the inspection images (510 and 520), respectively. As previously explained, existing VC inspection technologies have low sensitivity for detecting high-resistance defects, so the difference in voltage contrast signals is small, making existing technologies unsuitable for detecting, identifying, or even classifying these defects.

[0065] Now, referring to FIGS. 6a and FIGS. 6b, which respectively illustrate an exemplary methodology (600) for sample inspection according to embodiments of the present invention and a schematic plot of an exemplary plot of the number and capacity (frames) of defects for defect detection and classification. The methodology (600) can be used to improve detection sensitivity for high-resistance defects by improving the voltage contrast between defect-free features and defect-free features.

[0066] In some embodiments, high-resistance defects such as defect 308 may be detected in a neutral mode, also referred to herein as a neutral state. In the context of the invention, "neutral mode" refers to a mode or state in which the potential of a sample surface is neither negative nor positive. A "neutral charged" surface or a "substantially neutral charged" sample refers to a surface or sample in which there is no net charge and the negative and positive charges cancel each other out. In this context, a negative mode of the sample refers to a state in which the signal electron yield of a conductive feature (e.g., metal) is smaller than the signal electron yield of an insulating feature (e.g., oxide), and a positive mode of the sample surface refers to a state in which the signal electron yield of a conductive feature is larger than the signal electron yield of an insulating feature. In the neutral mode, the signal electron yields of the insulating feature and the conductive feature are substantially similar. Here, signal electron yield refers to the ratio of the total number of signal electrons generated (e.g., secondary electrons and backscattered electrons) to the total number of primary electrons irradiating the sample.

[0067] As previously explained, high-resistance defects are more difficult to detect in a single-scan VC inspection mode (negative or positive mode) because they have low signal strength and signal sensitivity. Although the sensitivity for detecting high-resistance defects is maximum in neutral mode, existing inspection techniques are very unstable in the neutral state and are unsuitable for defect detection, identification, or classification.

[0068] In some embodiments, the methodology (600) for defect detection may include a pre-charging step (605), an inspection scan step (625), and a defect classification step (650). The pre-charging step (605) may include the step of pre-charging features within the ROI by exposing the ROI of the sample to a beam of charged particles. Flooding the sample with charged particles, such as electrons, can negatively charge the surface, thereby improving the signal and voltage contrast of the features within the ROI.

[0069] The inspection step (625) may include a step of irradiating the ROI of a sample with a first capacitance of a charged particle beam, such as an electron beam, so that features within the ROI acquire a first polarity. In some embodiments, the first polarity refers to a negative state in which the sample surface is negatively charged. However, in some embodiments, the first polarity may refer to a positive state in which the sample surface is positively charged. In some embodiments, the ROI may be irradiated with the first charged particle capacitance in a negative mode or a positive mode. In a negative mode, the landing energy of the primary charged particle beam on the sample may be high, and the potential of the control electrode [e.g., the control electrode (232b) in FIG. 2] may be negative. In a positive mode, the landing energy of the primary charged particle beam on the sample may be low, but the potential of the control electrode may be positive. The potential of the control electrode may be configured to adjust the surface electric field, which may affect charge accumulation on the surface. The adjustment of the surface electric field and the landing energy of primary charged particles investigating the ROI can affect the signal charged particle yield. As previously described, in negative mode, the signal electron yield of a conductive feature (e.g., metal) is lower than that of an insulating feature (e.g., oxide), and in positive mode, the signal electron yield of a conductive feature is higher than that of an insulating feature. In some embodiments, the landing energy of the primary charged particles and the potential of the control electrode can be adjusted to adjust the polarity, and the beam current can be adjusted to adjust the charged particle capacity. A negative state, also referred to herein as a negative charge or negative condition, can negatively charge features (e.g., contacts) so that the features appear as dark voltage contrast features.

[0070] In some embodiments, the first charged particle capacity may include electrons forming a primary electron beam having a high average beam current. In some embodiments, the average beam current may be in the range of 100 nA to 500 nA, or 200 nA to 500 nA, or 300 nA to 500 nA, or 400 nA to 500 nA. In some embodiments, the average beam current of the high-capacity electron beam may be higher as needed.

[0071] The inspection step (625) may further include a step of scanning the ROI with a second primary charged particle capacity to cause the polarity of the sample surface to switch or transition from a first polarity to a second polarity opposite to the first polarity. If, in the pre-charging step (605), the sample pre-scanning charges the sample surface negatively (first polarity), the second primary charged particle capacity may be configured to switch the polarity to charge the surface positively (second polarity), and vice versa. In some embodiments, scanning the ROI with the second capacity may include scanning in a positive mode. In this case, the landing energy of the primary charged particle beam on the sample may be adjusted to be low, and the potential of the control electrode may be positive.

[0072] Switching the polarity of a sample, for example from a negative state to a positive state, may involve switching the polarity by applying the incremental capacitance of primary charged particles in a positive mode. As previously described, incremental capacitance refers to a gradual increase in the capacitance of charged particles. When switching polarity, the incremental capacitance may be applied in the opposite mode of the existing state. For example, if the sample is negatively charged, the incremental capacitance of the charged particles may be applied in a positive mode so that the sample eventually becomes positively charged. In a positive mode, the signal electron yield of conductive features is greater than that of insulating features; therefore, defect-free contacts (conductive) may appear as bright voltage contrast features, while defective contacts (high-resistance or non-conductive) may appear dark.

[0073] The inspection step (625) may further include the step of acquiring a plurality of inspection images, each image corresponding to one capacity of the incremental capacity. As shown in FIG. 6a, inspection image 610 of the ROI may correspond to a negative state of the sample, inspection image 612 of the ROI may correspond to capacity D1 of the incremental capacity, inspection image 614 of the ROI may correspond to a higher capacity D2 of the incremental capacity, inspection image 616 of the ROI may correspond to a much higher capacity D3 of the incremental capacity, and inspection image 618 of the ROI may correspond to capacity D n It can correspond to. The polarity of the ROI can become increasingly positive from inspection image 610 to inspection image 618.

[0074] When transitioning from a negative state to a positive state through the application of charged particles in a positive mode, the polarity of the ROI can be switched from negative to positive under switching conditions including the switching capacity of the charged particles. As used herein, the switching capacity refers to the capacity of the charged particles that causes the polarity of the ROI to switch from one polarity to the opposite polarity. In some embodiments, the switching capacity may be a predetermined beam current, or a narrow beam current distribution, or a wider beam current distribution. An exemplary distribution of the beam current for the switching capacity is described later with reference to FIG. 6b.

[0075] The inspection step (625) of the methodology (600) may further include a step of performing defect detection in each inspection image. Defect detection may be performed for each inspection image to generate corresponding defect features for each acquired inspection image. Performing defect detection may include, but is not limited to, performing die-to-die comparison, or performing cell-to-cell comparison, or performing die-to-database pixel.

[0076] Referring to FIG. 6b, which shows an exemplary plot of the number of defects detected for a capacity or inspection image according to embodiments of the present invention. The number of detected defects is displayed on the vertical y-axis, and the frame number or inspection image corresponding to one capacity of the incremental capacity is displayed on the horizontal x-axis.

[0077] In inspection image 610, the ROI of the sample is in a negative state due to negative pre-scan conditions. In this state, upon detection, defects such as electrical openness, also known as hard openness (e.g., defect 305 in Fig. 3b), may appear as bright features with high gray level values. This is because, in negative mode, the signal electron yield of insulating features, such as open defects, is greater than that of conductive features. In inspection image 612, corresponding to the charged particle capacity D1, the number of detected defects may be greater than the number of defects detected in inspection image 610 due to the higher capacity of the applied primary charged particles.

[0078] In some embodiments, capacitance D2 is a switching capacitance (D) in which the polarity of the sample or the ROI of the sample is switched from negative to positive. s It can be ). As mentioned earlier, switching capacity (D s ) may be a predetermined capacitance or capacitance range as shown in FIG. 6b and may represent a switching condition. The sample may be neutrally charged under the switching condition. In other words, the net charge or polarity of the sample under the switching condition is substantially zero. As shown in FIG. 6b, in some embodiments, the switching capacitance (D s The ) range may include leading edges and trailing edges. Switching capacity (D s A leading edge in the range may indicate the onset of a high-resistance defect. Although not shown, multiple inspection images are acquired between inspection image 612 and inspection image 614, which can enable defect detection at every capacity step of the incremental capacity applied to the sample, thereby enabling the capture of a high-resistance defect in the neutral state.

[0079] In conventional VC inspection technologies, high-resistance defects appear as dark features similar to normal contacts, which can lead to poor detection sensitivity and a low defect capture rate. In inspection images 610 and 612, high-resistance defects and normal contacts may appear as dark features, while electrical open circuits may appear as bright features. The large voltage contrast difference between normal contacts and electrical open circuits can lead to high sensitivity. However, due to the low voltage contrast difference between normal contacts and high-resistance defects, the detection sensitivity for high-resistance defects is poor, leading to a low defect capture rate and low inspection throughput.

[0080] In the negative and positive states corresponding to inspection images 610 and 618, respectively, high-resistance defects may not be distinguishable from normal contacts because the difference in signal strength is small. Both high-resistance defects and normal contacts may appear dark in inspection image 610 and bright in inspection image 618, making it difficult to detect these defects. However, for high-resistance defects, the transition speed from negative polarity to positive polarity is slower than that of normal contacts. Therefore, under neutral or switching conditions, high-resistance defects (e.g., defect 638) may appear as darker features compared to normal contacts (e.g., feature 632), as shown in FIG. 6c, thereby allowing the defect to be captured, identified, or classified.

[0081] The methodology (600) may further include a defect classification step (650). When determined, defects may be identified and classified based on a comparison of defect features from each inspection image. Defects may be classified based on one or more defect characteristics. In some embodiments, the characteristics of the defect may be the time of appearance of the defect, or the frame in which the defect first appeared, or the threshold capacity (D) that causes the defect to appear in the frame. tIt may include ), or the invariance of the defect, or the blinking period of the defect, etc. Critical capacity (D as used herein) t ) refers to the minimum dose of charged particles irradiated onto a sample to detect a defect in an inspection image. In some embodiments, the time of appearance of the defect in the image or the frame in which the defect first appears may be used to determine the threshold dose. As schematically illustrated in FIG. 4b, the number of detected defects may increase with increasing applied dose. Thus, the number of defects detected in the inspection image (455) corresponding to dose D4 may be greater than the number of defects detected in inspection images D3, D2, or D1, because D4 > D3 > D2 > D1. In other words, the threshold dose for defect detection may be based on data associated with the inspection image in which the defect first appears. In some embodiments, the threshold dose (D t ) may be based on the defect type, or defect location, or detection sensitivity of the charged particle detector, etc. In some embodiments, the critical capacitance may be determined based on the capacitance of features associated with the defect. In some embodiments, defect characteristics may include defect invariance or bling period. If the defect appears consistently in each frame of a plurality of frames obtained, the defect may be a fixed defect. If the defect is a bling defect (such as bling defect 472), the bling period of the bling defect (472) may be determined based on the time difference between the first appearance and the second appearance. Time information may be obtained based on the scan rate, scan frequency, or time delay between scans.

[0082] Now, referring to FIG. 7, which is an exemplary flowchart illustrating an exemplary method (700) of sample inspection for defect detection using a charged particle beam device according to embodiments of the present invention. One or more steps of the method (700) may be performed by a controller (50) of an EBI system (100) as shown in FIG. 2, for example. Here, the controller (50) may instruct a module of the charged particle beam device to activate a charged particle source to generate a primary charged particle beam (e.g., an electron beam), to acquire an inspection image based on detected signal charged particles generated from a sample, or to perform other related functions.

[0083] In step 710, a region of the sample containing multiple features may be charged with a first polarity. A charged particle source of a charged particle beam device, such as a SEM, is activated to emit charged particles (e.g., electrons). The charged particles may form a charged particle beam [e.g., the primary charged particle beam (204) of FIG. 2 or a primary electron beam]. The electron source may be activated by a controller [e.g., the controller (50) of FIG. 2]. For example, the electron source may be controlled to emit primary electrons to form an electron beam along a primary optical axis [e.g., the primary optical axis (201) of FIG. 2]. The electron source may be activated remotely, for example, by software, an application, or a processor of the controller using a set of instructions to power the electron source through a control circuit. The primary electron beam can pass through a Coulomb aperture array [e.g., Coulomb aperture array (224) in FIG. 2] and a beam-limiting aperture array (not shown) to adjust the beam size or beam current of the primary electron beam and form a probing beam incident on a sample [e.g., sample (250) in FIG. 2]. The primary electron beam can be configured to precharge the sample by irradiating the ROI of the sample with high-capacity primary electrons.

[0084] In some embodiments, the first polarity refers to a negative state in which the sample surface is negatively charged. However, in some embodiments, the first polarity may refer to a positive state in which the sample surface is positively charged. In some embodiments, the ROI may be irradiated with a first charged particle capacity in a negative mode or a positive mode. In the negative mode, the landing energy of the primary charged particle beam on the sample may be high, and the potential of the control electrode [e.g., the control electrode (232b) in FIG. 2] may be negative. In the positive mode, the landing energy of the primary charged particle beam on the sample may be low, but the potential of the control electrode may be positive. In some embodiments, the landing energy of the primary charged particles and the potential of the control electrode may be adjusted to adjust the polarity, and the beam current may be adjusted to adjust the charged particle capacity. In some embodiments, the average beam current may be in the range of 100 nA to 500 nA, or 200 nA to 500 nA, or 300 nA to 500 nA, or 400 nA to 500 nA.

[0085] In step 720, the polarity of the ROI may be switched from a first polarity to a second polarity under a switching condition. The switching condition may include the switching capacitance of the primary charged particles. The ROI may be scanned with a second primary charged particle capacitance to cause the polarity of the sample surface to be switched from a first polarity to a second polarity opposite to the first polarity. If the sample pre-scan charges the sample surface negatively (first polarity), the second primary charged particle capacitance may be configured to switch the polarity to charge the surface positively (second polarity), and vice versa. In some embodiments, scanning the ROI with the second capacitance may include scanning in a positive mode. In this case, the landing energy of the primary charged particle beam on the sample may be adjusted to be low, and the potential of the control electrode may be positive. Switching the polarity of a sample, for example from a negative state to a positive state, may involve switching the polarity by applying the incremental capacitance of primary charged particles in a positive mode. As previously described, incremental capacitance refers to a gradual increase in the capacitance of charged particles. When switching polarity, the incremental capacitance may be applied in the opposite mode of the existing state. For example, if the sample is negatively charged, the incremental capacitance of the charged particles may be applied in a positive mode so that the sample eventually becomes positively charged. In a positive mode, the signal electron yield of conductive features is greater than that of insulating features; therefore, defect-free contacts (conductive) may appear as bright voltage contrast features, while defective contacts (high-resistance or non-conductive) may appear dark.

[0086] Switching capacity (D s ) refers to the capacitance of charged particles (e.g., electrons) that causes the polarity of a sample or the ROI of the sample to switch from negative to positive. Switching capacitance (D s) may be a predetermined capacitance or capacitance range as shown in FIG. 6b and may represent a switching condition. The sample may be neutrally charged under the switching condition. In other words, the net charge or polarity of the sample under the switching condition is substantially zero. In some embodiments, the switching capacitance may be a predetermined beam current, or a narrow beam current distribution, or a wider beam current distribution.

[0087] In step 730, an inspection image of the ROI may be formed from signal charged particles—such as secondary electrons, backscattered electrons, etc., generated upon interaction between the switching capacitance of primary charged particles and a plurality of features, but not limited thereto. In some embodiments, one or more inspection images may be obtained, each image corresponding to the applied capacitance of the incremental capacitance. In some embodiments, a charged particle detector may be used to detect signal charged particles generated from the ROI of the sample upon interaction with the charged particles of the primary charged particle beam. An image may be formed based on the detected signal charged particles. The image formed may include an SEM image or other suitable grayscale image.

[0088] In step 740, one or more defects may be detected in the inspection image corresponding to the switching capacity. Defect detection may be performed on the inspection image to generate corresponding defect features. Performing defect detection may include, but is not limited to, performing die-to-die comparison, performing cell-to-cell comparison, or performing die-to-database pixel analysis. In die-to-die mode, inspection images of two or more dies may be compared to detect defects within the inspection images. For example, multi-scan inspection of a sample containing multiple dies may include acquiring 25 frames of each die on the wafer, and defects may be identified within each frame for all dies. In this scenario, for example, the 20th frame for all dies may be compared to identify defects. The comparison of frames or inspection images may include, for example, visual inspection that identifies defects based on the gray level values ​​of features. In cell-to-cell mode, defect detection may be based on the locations of features within the iteration units of the cell or die. For example, multi-scan inspection of an ROI containing cells may include acquiring multiple images of the cells. In an inspection image of a cell containing multiple arranged features, the presence of a feature at an unintended location or the absence of a feature at an expected location of the arrangement may indicate the presence of a defect. The intended or expected location may be based on the characteristics of the arranged pattern of features within the cell or other similar cells. In die-database pixel counting mode, an inspection image of the die may be compared with a reference image or reference layout of the die. The reference image or reference layout may be a database image or a reference feature layout.Reference feature information can be obtained from an information file containing a wafer design layout in a Graphic Database System (GDS) format, Graphic Database System II format, or Open Artwork System Interchange Standard (OASIS) format containing a graphic representation of features on the wafer surface.

[0089] Defects can be detected based on the gray level values ​​of features in the acquired inspection image(s). In negative and positive states, high-resistance defects may not be distinguishable from normal contacts because the difference in signal strength is negligible. Both high-resistance defects and normal contacts may appear dark in the inspection image (e.g., inspection image 610 in FIG. 6a) and bright in the inspection image (e.g., inspection image 618 in FIG. 6a), making it difficult to detect these defects. However, for high-resistance defects, the transition speed from negative polarity to positive polarity is slower than that of normal contacts. Therefore, under neutral or switching conditions, high-resistance defects (e.g., defect 638) may appear as darker features compared to normal contacts (e.g., feature 632), as shown in FIG. 6c, thereby allowing the presence of defects to be determined based on the gray level values ​​of the features.

[0090] Some of the advantages of capacitance-controlled voltage contrast defect detection include improved inspection throughput, higher defect detection sensitivity, defect classification, improved detection signal, defect location identification, and compatibility with single-beam and multi-beam inspection devices.

[0091] A non-transient computer-readable medium may be provided for storing instructions for a processor of a controller [e.g., controller (50) of FIG. 1] to perform image inspection, image acquisition, charge-particle source activation, inspection of a region of a sample at a first charge particle dose, inspection of a region of a sample at a second charge particle dose different from the first dose, determination of the presence of defects based on gray level values ​​of features from the acquired image of a region of a sample, and the functions described in the methods (400 and 700). Common forms of non-transient media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tapes, or any other magnetic data storage media, CD-ROM (Compact Disc Read Only Memory), any other optical data storage media, any physical media having patterns of holes, RAM (Random Access Memory), PROM (Programmable Read Only Memory), and EPROM (Erasable Programmable Read Only Memory), FLASH-EPROM or any other flash memory, NVRAM (Non-Volatile Random Access Memory), caches, registers, any other memory chips or cartridges, and networked versions thereof.

[0092] Embodiments of the present invention may be further described using the following items:

[0093] 1. A method for inspecting a sample using a charged particle beam device,

[0094] A step of charging a region of a sample containing a plurality of features with a first polarity;

[0095] A step of causing the above region to switch from a first polarity to a second polarity under a switching condition - the switching condition includes the switching capacitance of primary charged particles - ;

[0096] A step of forming an inspection image of the region from signal charged particles generated after the interaction of switching capacities of a plurality of features and primary charged particles; and

[0097] A method comprising the step of determining whether a feature among a plurality of features has a defect based on the gray level value of the feature in an inspection image.

[0098] 2. A method in claim 1, wherein charging the zone to a first polarity comprises flooding the zone with a first capacity of primary charged particles emitted from a charged particle source of a charged particle beam device.

[0099] 3. A method in which, in claim 1 or 2, the first capacitance of the primary charged particles is configured to pre-charge the region.

[0100] 4. A method in any one of claims 1 to 3, wherein the switching capacity is smaller than the first capacity of the primary charged particles.

[0101] 5. A method further comprising the step of irradiating the zone with a second dose of primary charged particles configured to form a probing beam, in any one of claims 1 to 4.

[0102] 6. A method comprising, in any one of claims 1 to 5, further a step of adjusting an electric field associated with a zone to adjust the net charge of the investigated zone.

[0103] 7. In Clause 6, the step of adjusting the electric field is:

[0104] Adjusting the landing energy of primary charged particles on a sample; and

[0105] A method comprising controlling the accumulation of signal-charged particles on a sample.

[0106] 8. A method in any one of claims 1 to 7, wherein the first polarity of the zone comprises a negative charge and the second polarity of the zone comprises a positive charge.

[0107] 9. A method in which, in any one of claims 1 to 8, the zone is charged neutrally under switching conditions.

[0108] 10. A method in any one of claims 1 to 9 in which the gray level value of the defective feature is higher than the gray level value of the non-defective feature.

[0109] 11. A method further comprising the step of identifying a defect associated with a defective feature based on the switching capacity of primary charged particles in claim 10.

[0110] 12. In claim 11, the defect comprises an electrical open or high-resistance defect.

[0111] 13. A method in any one of claims 1 to 12, wherein the feature comprises a contact pad configured to form an electrical connection to a capacitor.

[0112] 14. In claim 13, the capacitor comprises a word-line of a memory device.

[0113] 15. A method for inspecting a sample using a charged particle beam device,

[0114] A step of charging a region of a sample containing a plurality of features to a first polarity by irradiating the region with a first primary charged particle capacity;

[0115] A step of making the above region charged with a second polarity by scanning the region with a plurality of scans of a second primary charged particle capacity;

[0116] A step of forming a plurality of inspection images from signal charged particles generated after the interaction of primary charged particles of each scan of the above-mentioned area and a plurality of scans;

[0117] A step of determining whether a feature has a defect based on a comparison of gray level values ​​of multiple features in multiple inspection images; and

[0118] A method comprising the step of identifying the characteristics of a defect based on an inspection image and the corresponding primary charged particle capacity after determination.

[0119] 16. A method in claim 15 further comprising the step of switching from a first polarity to a second polarity in the switching capacity of primary charged particles, wherein the switching capacity comprises at least one applied capacity of the second primary charged particle capacity.

[0120] 17. In claim 16, the switching capacity is smaller than the first primary charged particle capacity.

[0121] 18. A method in any one of claims 15 to 17, wherein the first primary charged particle capacity is configured to pre-charge the region.

[0122] 19. A method in any one of claims 15 to 18, wherein the second primary charged particle capacity is configured to form a probing beam.

[0123] 20. A method comprising, in any one of claims 15 to 19, further a step of adjusting an electric field associated with a zone to adjust the net charge of the investigated zone.

[0124] 21. In Clause 20, the step of adjusting the electric field is:

[0125] Adjusting the landing energy of primary charged particles on a sample; and

[0126] A method comprising controlling the accumulation of signal-charged particles on a sample.

[0127] 22. A method in any one of claims 15 to 21, wherein the first polarity of the zone comprises a negative charge and the second polarity of the zone comprises a positive charge.

[0128] 23. A method in which, in any one of claims 16 to 22, the area is charged neutrally in the switching capacity.

[0129] 24. A method in any one of claims 16 to 23 in which the gray level value of a defective feature is higher than the gray level value of a non-defective feature in an inspection image corresponding to the switching capacity.

[0130] 25. A method further comprising the step of identifying a defect associated with a defective feature based on the switching capacity of primary charged particles in claim 24.

[0131] 26. In paragraph 25, the defect comprises an electrical open or high-resistance defect.

[0132] 27. A method in any one of claims 15 to 26, wherein the feature comprises a contact pad, and the contact pad is configured to form an electrical connection to a capacitor.

[0133] 28. In claim 27, the capacitor comprises a word-line of a memory device.

[0134] 29. A method in any one of claims 15 to 28, wherein a plurality of scans includes a first scan and a second scan, and the capacity of the second scan is higher than the capacity of the first scan.

[0135] 30. In claim 29, the method in which the capacity for the second scan is the sum of the first scan and the second scan.

[0136] 31. A method in which, in claim 29 or 30, the plurality of scans further comprises a third scan, and the capacity of the third scan is the sum of the capacities for the first scan, the second scan, and the third scan.

[0137] 32. As a charged particle beam device,

[0138] A charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam, and the charged particle beam device is:

[0139] A region of a sample containing multiple features is charged with a first polarity, and

[0140] Under switching conditions, the above region is configured to switch from a first polarity to a second polarity, and the switching condition includes the switching capacitance of primary charged particles; and

[0141] Controller including circuit - This is:

[0142] Acquiring an inspection image of the said region from signal charged particles generated during the interaction of switching capacitances of multiple features and primary charged particles, and

[0143] A charged particle beam device comprising: configured to determine whether a feature is defective based on the gray level value of the feature in an inspection image.

[0144] 33. A charged particle beam device configured to charge the region to a first polarity by irradiating the region with a first charged particle capacity of a primary charged particle beam configured to pre-charge the region in claim 32.

[0145] 34. A charged particle beam device configured such that the first capacitance of primary charged particles in claim 32 or 33 pre-charges the said region.

[0146] 35. A charged particle beam device in any one of claims 32 to 34, wherein the switching capacity is smaller than the first capacity of the primary charged particles.

[0147] 36. A charged particle beam device configured to charge the region to a second polarity by irradiating the region with a second charged particle capacity of a primary charged particle beam configured to probe the region in any one of claims 32 to 35.

[0148] 37. A charged particle beam device further configured to adjust an electric field associated with a zone to adjust the net charge of the irradiated zone in any one of claims 32 to 36.

[0149] 38. In Clause 37, the adjustment of the electric field associated with the above zone is:

[0150] Coordination of the landing energy of primary charged particles on the sample; and

[0151] A charged particle beam device comprising the adjustment of the accumulation of signal-charged particles on a sample.

[0152] 39. A charged particle beam device in any one of claims 32 to 38, wherein the first polarity of the zone comprises a negative charge and the second polarity of the zone comprises a positive charge.

[0153] 40. A charged particle beam device configured to neutrally charge the region under switching conditions in any one of claims 32 to 39.

[0154] 41. A charged particle beam device in any one of claims 32 to 40, wherein the gray level value of a defective feature is higher than the gray level value of a non-defective feature.

[0155] 42. In claim 41, a charged particle beam device further configured such that a controller including a circuit identifies a defect associated with a defective feature based on the switching capacity of primary charged particles.

[0156] 43. In Clause 42, the defect is a charged particle beam device including an electrical open or high-resistance defect.

[0157] 44. In any one of claims 32 to 43, the feature comprises a charged particle beam device comprising a contact pad configured to form an electrical connection to a capacitor.

[0158] 45. In claim 44, the capacitor is a charged particle beam device comprising a word-line of a memory device.

[0159] 46. ​​As a charged particle beam device,

[0160] A charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam, and the charged particle beam device is:

[0161] A region of a sample including multiple features is charged with a first polarity by irradiating the region with a first primary charged particle capacity, and

[0162] The above region is configured to be charged with a second polarity by scanning the region with a plurality of scans of a second primary charged particle capacity- ; and

[0163] Controller including circuit - This is:

[0164] Acquiring multiple inspection images from signal charged particles generated after the interaction of primary charged particles of each scan of the above-mentioned area and multiple scans, and

[0165] Determining whether a feature has a defect based on a comparison of the gray level values ​​of multiple features in multiple inspection images,

[0166] A charged particle beam device comprising: configured to identify defect characteristics based on inspection images and corresponding primary charged particle capacities after determination.

[0167] 47. A charged particle beam device in claim 46, further configured to cause switching from a first polarity to a second polarity in the switching capacity of primary charged particles, wherein the switching capacity comprises at least one applied capacity of a second primary charged particle capacity.

[0168] 48. In claim 47, a charged particle beam device in which the switching capacity is smaller than the first primary charged particle capacity.

[0169] 49. A charged particle beam device configured such that, in any one of claims 46 to 48, the first primary charged particle capacity pre-charges a region.

[0170] 50. In any one of claims 46 to 49, a charged particle beam device configured such that the second primary charged particle capacity is configured to probe a zone.

[0171] 51. A charged particle beam device further configured to adjust an electric field associated with a zone to adjust the net charge of the irradiated zone in any one of claims 46 to 50.

[0172] 52. In Paragraph 51, the adjustment of the electric field associated with the zone is:

[0173] Coordination of the landing energy of primary charged particles on the sample; and

[0174] A charged particle beam device comprising the adjustment of the accumulation of signal-charged particles on a sample.

[0175] 53. A charged particle beam device in any one of claims 46 to 52, wherein the first polarity of the zone comprises a negative charge and the second polarity of the zone comprises a positive charge.

[0176] 54. A charged particle beam device further configured to neutrally charge the region in a switching capacity in any one of claims 46 to 53.

[0177] 55. A charged particle beam device in any one of claims 46 to 54, wherein the gray level value of a defective feature is higher than the gray level value of a non-defective feature in an inspection image corresponding to the switching capacity.

[0178] 56. In claim 55, a charged particle beam device further configured such that a controller including a circuit identifies a defect associated with a defective feature based on the switching capacity of primary charged particles.

[0179] 57. In claim 56, the defect is a charged particle beam device including an electrical open or high-resistance defect.

[0180] 58. A charged particle beam device in any one of claims 46 to 57, wherein the feature comprises a contact pad, and the contact pad is configured to form an electrical connection to a capacitor.

[0181] 59. In claim 58, the capacitor is a charged particle beam device comprising a word-line of a memory device.

[0182] 60. A charged particle beam device in any one of claims 46 to 59, wherein the plurality of scans includes a first scan and a second scan, and the capacity of the second scan is higher than the capacity of the first scan.

[0183] 61. A charged particle beam device in which, in claim 60, the capacity for the second scan is twice the capacity for the first scan.

[0184] 62. A charged particle beam device in claim 60 or 61, wherein the plurality of scans further comprises a third scan, and the capacity of the third scan is the sum of the capacities for the first scan and the second scan.

[0185] 63. A non-transient computer-readable medium storing a set of executable instructions to enable a charged particle beam device to perform a method of inspecting a sample by one or more processors of a charged particle beam device,

[0186] The above method is:

[0187] A step of activating a charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam— ;

[0188] A step of irradiating a region of a sample containing a plurality of features using a primary charged particle beam to charge said region with a first polarity;

[0189] A step of irradiating the above region using a primary charged particle beam to switch from a first polarity to a second polarity under switching conditions - the switching condition includes the switching capacitance of the primary charged particles - ;

[0190] A step of forming an inspection image of the region from signal charged particles generated after the interaction of switching capacities of a plurality of features and primary charged particles; and

[0191] A non-transient computer-readable medium comprising the step of determining whether a feature among a plurality of features is defective based on the gray level value of the feature in an inspection image.

[0192] 64. A non-transient computer-readable medium storing a set of executable instructions to enable a charged particle beam device to perform a method of inspecting a sample by one or more processors of a charged particle beam device,

[0193] The above method is:

[0194] A step of activating a charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam— ;

[0195] A step of irradiating a region of a sample containing a plurality of features using the first charged particle capacitance of a primary charged particle beam to charge said region with a first polarity;

[0196] A step of scanning the region with a plurality of scans of the second charged particle capacitance of the primary charged particle beam to charge the region with a second polarity;

[0197] A step of forming a plurality of inspection images from signal charged particles generated after the interaction of primary charged particles of each scan of the above-mentioned area and a plurality of scans;

[0198] A step of determining whether a feature has a defect based on a comparison of gray level values ​​of multiple features in multiple inspection images; and

[0199] A non-transient computer-readable medium comprising the step of identifying the characteristics of a defect based on an inspection image and the corresponding primary charged particle capacity after determination.

[0200] 65. In paragraph 64, the above method is:

[0201] A step of inspecting at least two of a plurality of inspection images;

[0202] A step of determining whether defective features exist in at least two inspection images; and

[0203] A non-transient computer-readable medium comprising the step of further storing information associated with at least two inspection images and corresponding capacities in a database after determination.

[0204] 66. In claim 65, the method further comprises the step of examining each image of a plurality of examination images in a non-transient computer-readable medium.

[0205] It will be understood that the embodiments of the present invention are not limited to the exact configurations described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The present invention has been described in relation to various embodiments, and other embodiments of the present invention will be apparent to those skilled in the art by considering the practice and specifications of the invention disclosed herein. Specifications and examples are to be regarded merely as illustrative, and the true scope and technical spirit of the present invention are intended to be indicated by the following claims.

[0206] The foregoing description is for illustrative purposes only and is not intended to be restrictive. Therefore, those skilled in the art will clearly understand that variations as described below can be made without departing from the scope of the claims set forth below.

Claims

Claim 1 A method for inspecting a sample using a charged particle beam device, comprising: a step of charging a region of a sample containing a plurality of features to a first polarity; a step of switching the region from the first polarity to a second polarity under a switching condition, wherein the switching condition includes a switching dosage of primary charged particles; a step of forming an inspection image of the region from signal charged particles generated after the interaction of the plurality of features and the switching dosage of the primary charged particles; and a step of determining whether there is a defect in the features of the plurality of features based on the gray level value of the features in the inspection image. Claim 2 As a charged particle beam device, a charged particle source configured to emit charged particles - the emitted charged particles form a primary charged particle beam, and said charged particle beam device: A region of a sample containing multiple features is charged with a first polarity, and A controller comprising a circuit, wherein the above region is configured to switch from the first polarity to the second polarity under a switching condition, and the switching condition includes the switching capacitance of primary charged particles; and the controller comprises: An inspection image of the region is obtained from signal charged particles generated during the interaction of the switching capacitance of the plurality of features and the primary charged particles, and A charged particle beam device comprising: configured to determine whether a feature has a defect based on the gray level value of the feature in the inspection image above. Claim 3 In claim 2, the charged particle beam device is configured to charge the region to the first polarity by irradiating the region with the first charged particle capacity of the primary charged particle beam configured to pre-charge the region. Claim 4 In claim 2, a charged particle beam device configured such that the first capacitance of the primary charged particles pre-charges the said region. Claim 5 In claim 2, the charged particle beam device, wherein the switching capacity is smaller than the first capacity of the primary charged particles. Claim 6 In claim 2, the charged particle beam device is configured to charge the region to the second polarity by irradiating the region with the second charged particle capacity of the primary charged particle beam configured to probe the region. Claim 7 A charged particle beam device according to claim 2, further configured to adjust an electric field associated with said zone to adjust the net charge of said zone. Claim 8 A charged particle beam device according to claim 7, wherein the adjustment of the electric field associated with the zone comprises: adjustment of the landing energy of primary charged particles on the sample; and adjustment of the accumulation of signal charged particles on the sample. Claim 9 A charged particle beam device according to claim 2, wherein the first polarity of the zone comprises a negative charge and the second polarity of the zone comprises a positive charge. Claim 10 In claim 2, the charged particle beam device is configured to neutralize the region under the switching conditions. Claim 11 In claim 2, a charged particle beam device in which the gray level value of a defective feature is higher than the gray level value of a non-defective feature. Claim 12 A charged particle beam device according to claim 11, wherein the controller including the circuit is further configured to identify a defect associated with the defective feature based on the switching capacity of the primary charged particles. Claim 13 In claim 12, the defect comprises an electrically open or high-resistance defect, a charged particle beam device. Claim 14 In claim 2, the charged particle beam device comprises a contact pad configured to form an electrical connection to a capacitor. Claim 15 A non-transitory computer-readable medium storing a set of executable instructions to cause one or more processors of a charged particle beam device to perform a method of inspecting a sample, wherein the method comprises: activating a charged particle source configured to emit charged particles—the emitted charged particles form a primary charged particle beam—; irradiating a region of a sample containing a plurality of features using a first charged particle capacity of the primary charged particle beam to charge the region with a first polarity; scanning the region with a plurality of scans of a second charged particle capacity of the primary charged particle beam to charge the region with a second polarity; forming a plurality of inspection images from signal charged particles generated after the interaction of the primary charged particles of each scan of the region and the primary charged particles of the plurality of scans; and determining whether there is a defect in the feature based on a comparison of the gray level values ​​of the plurality of features in the inspection images of the plurality of inspection images. A non-transient computer-readable medium comprising the step of identifying the characteristics of a defect based on the inspection image and the corresponding primary charged particle capacity after determination.

Images