A distributed system for wafer print check

Abstract

A method for performing a distributed wafer print check includes: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; providing the defect locations of the zone of the first wafer to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein the zone of the first wafer is in a same location as the zone of the second wafer and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.

Description

A DISTRIBUTED SYSTEM FOR WAFER PRINT CHECKCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 609,858 which was filed on 13 December 2023 and which is incorporated herein in its entirety by referenceTECHNICAL FIELD

[0002] The embodiments provided herein relate to a wafer print check process, and more particularly to a method and system for a distributed wafer print check process.BACKGROUND

[0003] The wafer print check process finds particles (e.g., physical defects) falling on reticles (e.g., a photolithography mask) in extreme ultraviolet (EUV) scanners by inspecting printed wafers. Repeated defects found at the same locations in different inspection fields are reported as mask-caused defects. To find the mask-caused defects, a full field is first inspected to find defect candidates. As the defect candidates are reported once in a single field, it is not clear if they are repeated defects in other fields. These defect candidate locations are used to inspect in multiple fields of the wafer to check whether each defect candidate is repeated in other fields. Either optical bright field inspection (BFI) or multibeam inspection (MBI) may be used for full field inspection. The repeater defect detection may be performed by a scanning electron microscope (SEM) sequentially after the full wafer is inspected (e.g., by BFI) or after a full field inspection (e.g., by MBI).

[0004] The MBI full field inspection is slower than optical inspection tools (e.g., BFI). For example, an optical inspection tool can inspect a wafer within one hour, while an MBI tool with multiple beams may inspect one field of the wafer in the same time frame. BFI can be used to perform a full wafer inspection and do rough repeater analysis followed with additional defects reviewed by SEM tools. However, the MBI tool inspects one full field and it would take too long to inspect multiple full fields to perform the repeater analysis. If it is necessary to wait until the MBI tool finishes the full field inspection before starting the repeater defect detection, it adds to the total cycle time for the wafer print check process.SUMMARY

[0005] Some embodiments provide a method for performing a distributed wafer print check. The method may include: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; providing the defect locations of the zone of the first wafer to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein the zone of the first wafer is in a same location as the zone of the second wafer and the secondinspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.

[0006] Some embodiments provide a system for performing a distributed wafer print check. The system includes a plurality of first inspection tools, a plurality of second inspection tools, and a server communicatively coupled with the plurality of first inspection tools and the plurality of second inspection tools. Each of the plurality of first inspection tools is configured to receive a first wafer, inspect a zone of a full field of the first wafer, and determine defect locations in the zone of the first wafer. The server is configured to receive the defect locations of the zone of the first wafer from each of the plurality of first inspection tools and send the defect locations of the zone of the first wafer to one of the plurality of second inspection tools. Each of the plurality of second inspection tools is configured to receive a second wafer; determine whether the defect locations of the zone of the first wafer repeat in a zone of the second wafer, wherein the zone of the first wafer is in a same location as the zone of the second wafer; and inspect the zone of the second wafer while each of the plurality of first inspection tools inspects another zone of the first wafer.

[0007] Some embodiments provide a non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for performing a distributed wafer print check. The operations include: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; receiving the defect locations of the zone of the first wafer from the first inspection tool by a server; sending the defect locations of the zone of the first wafer from the server to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein the zone of the first wafer is in a same location as the zone of the second wafer and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer. Other advantages of the embodiments of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of the present invention.BRIEF DESCRIPTION OF FIGURES

[0008] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments, taken in conjunction with the accompanying drawings.

[0009] Fig. 1 is a flow diagram of an in-sequence repeater defect detection process.

[0010] Fig. 2 is a schematic diagram illustrating an example charged-particle beam inspection (CPBI) system, consistent with some embodiments of the present disclosure.

[0011] Fig. 3 is a schematic diagram illustrating an example charged-particle beam tool, consistent with some embodiments of the present disclosure that may be a part of the example charged-particle beam inspection system of Fig. 2.

[0012] Fig. 4 is a schematic diagram illustrating an example multi-beam tool, consistent with embodiments of the present disclosure that can be a part of the example charged-particle beam inspection system of Fig. 2.

[0013] Fig. 5 is a block diagram of an exemplary server, consistent with some embodiments of the present disclosure.

[0014] Fig. 6 is a flow diagram of an in-parallel repeater defect detection process, consistent with embodiments of the present disclosure.

[0015] Fig. 7 is a schematic diagram of a system for performing an in-parallel repeater defect detection process, consistent with embodiments of the present disclosure.

[0016] Fig. 8 is a schematic diagram of another system for performing an in-parallel repeater defect detection process, consistent with embodiments of the present disclosure.

[0017] Fig. 9 is a flowchart of an example method for a distributed wafer print check process, consistent with embodiments of the present disclosure.DETAILED DESCRIPTION

[0018] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations. Instead, they are merely examples of apparatuses and methods consistent with aspects related to the disclosed embodiments as recited in the appended claims. For example, although some embodiments are described in the context of utilizing electron beams, the disclosure is not so limited. Other types of charged-particle beams (e.g., including protons, ions, muons, or any other particle carrying electric charges) may be similarly applied. Furthermore, other imaging systems may be used, such as optical imaging, photon detection, x-ray detection, ion detection, etc.

[0019] Relative dimensions of components in drawings may be exaggerated for clarity. Within the following description of drawings, the same or like reference numbers refer to the same or like components or entities, and only the differences with respect to the individual embodiments are described. As used herein, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, if it is stated that a component may include A or B, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component may include A, B, or C, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0020] Electronic devices are constructed of circuits formed on a piece of semiconductor material called a substrate. The semiconductor material may include, for example, silicon, gallium arsenide,indium phosphide, or silicon germanium, or the like. Many circuits may be formed together on the same piece of silicon and are called integrated circuits or ICs. The size of these circuits has decreased dramatically so that many more of them can be fit on the substrate. For example, an IC chip in a smartphone can be as small as a thumbnail and yet may include over 2 billion transistors, the size of each transistor being less than 1 / lOOOth the size of a human hair.

[0021] Making these ICs with extremely small structures or components is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. Errors in even one step have the potential to result in defects in the finished IC, rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects to maximize the number of functional ICs made in the process; that is, to improve the overall yield of the process.

[0022] One component of improving yield is monitoring the chip-making process to ensure that it is producing a sufficient number of functional integrated circuits. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection can be carried out using a scanning charged-particle microscope (SCPM). For example, an SCPM may be a scanning electron microscope (SEM). An SCPM can be used to image these extremely small structures, in effect, taking a “picture” of the structures of the wafer. The image can be used to determine if the structure was formed properly in the proper location. If the structure is defective, then the process can be adjusted, so the defect is less likely to recur.

[0023] The working principle of an SCPM (e.g., an SEM) is similar to a camera. A camera takes a picture by receiving and recording intensity of light reflected or emitted from people or objects. An SCPM takes a “picture” by receiving and recording energies or quantities of charged particles (e.g., electrons) reflected or emitted from the structures of the wafer. Typically, the structures are made on a substrate (e.g., a silicon substrate) that is placed on a platform, referred to as a stage, for imaging. Before taking such a “picture,” a charged-particle beam may be projected onto the structures, and when the charged particles are reflected or emitted (“exiting”) from the structures (e.g., from the wafer surface, from the structures underneath the wafer surface, or both), a detector of the SCPM may receive and record the energies or quantities of those charged particles to generate an inspection image. To take such a “picture,” the charged-particle beam may scan through the wafer (e.g., in a line-by-line or zigzag manner), and the detector may receive exiting charged particles coming from a region under charged particle -beam projection (referred to as a “beam spot”). The detector may receive and record exiting charged particles from each beam spot one at a time and join the information recorded for all the beam spots to generate the inspection image. Some SCPMs use a single charged-particle beam (referred to as a “single-beam SCPM,” such as a single-beam SEM) to take a single “picture” to generate the inspection image, while some SCPMs use multiple charged-particle beams (referred to as a “multi-beam SCPM,” such as a multi-beam SEM) to take multiple “sub-pictures” of the wafer in parallel and stitch them together to generate the inspection image. By using multiple charged-particle beams, the SCPM may provide more charged-particle beams onto the structures for obtaining these multiple “sub-pictures,”resulting in more charged particles exiting from the structures. Accordingly, the detector may receive more exiting charged particles simultaneously and generate inspection images of the structures of the wafer with higher efficiency and faster speed.

[0024] As the physical sizes of IC components continue to shrink, accuracy and yield in defect detection become more important. Metrology tools can be used to determine whether the ICs are correctly manufactured by identifying a number of defects on each wafer, including at different levels of detail, such as a pattern level, an image (field of view) level, a die level, a care area level, or a wafer level.

[0025] Fig. 1 is a flow diagram of an in-sequence repeater defect detection process 100. The process 100 is performed by a full field inspection tool 102 and a repeater defect detection tool 104. The full field inspection tool 102 performs a full field inspection. As used herein, the terms “full field” or “field” indicate an area that can be inspected by a tool at one time. For example, the area may have a size of 26 millimeters (mm) by 33 mm. All defect candidates 106 that were detected during the full field inspection process are collected. When the full field is inspected, it is not certain whether those defects are repeating defects or not. If the defects repeat in different fields, it indicates that there are defects on the mask (i.e., if there is a mask defect, the particle will appear at the same location in all fields).

[0026] After the full field inspection is completed, a list of all the defect candidates 106 is sent to the repeater defect detection tool 104 for performing the repeater defect detection process. The repeater defect detection tool 104 looks at the locations identified in the list of defect candidates 106 in other fields to verify whether the detected defects repeat in the other fields. As noted above, if a defect repeats in more than one field, this indicates that the defect is caused by a mask defect. In some embodiments, the full field inspection tool 102 and the repeater defect detection tool 104 may be contained in a single tool. The repeater defect detection tool 104 reports the results of the repeater defect detection process to, for example, a user or an operator of the repeater defect detection tool 104.

[0027] Embodiments of the present disclosure can provide a way to perform a distributed wafer print check. According to some embodiments of the present disclosure, a zone (i.e., a portion) of a full field (i.e., an area that can be inspected by a tool at one time) of a first wafer is inspected by a first inspection tool (e.g., an MBI tool). A server receives a list of defect locations in the zone from the first inspection tool. The server sends the list of defect locations to a second inspection tool (e.g., an SBI tool), which inspects the same locations on a second wafer to determine whether the defect locations in the zone on the first wafer repeat in the same zone on the second wafer. The second wafer should be fabricated with the same process as the first wafer. If there are repeating defects in the same location on the second wafer, this indicates that there may be a mask-related defect that should be corrected. While the second inspection tool is inspecting the zone on the second wafer, the first inspection tool may inspect a different zone on the first wafer. By simultaneously inspecting the first wafer and the second wafer, the repeating defect determination may be completed faster than fully inspecting the first wafer and then performing repeat detection on the second wafer.

[0028] Fig. 2 illustrates an exemplary charged-particle beam inspection (CPBI) system 200 consistent with some embodiments of the present disclosure. CPBI system 200 may be used for imaging. For example, CPBI system 200 may use an electron beam for imaging. As shown in Fig. 2, CPBI system 200 includes a main chamber 201, a load / lock chamber 202, a beam tool 204, and an equipment front end module (EFEM) 206. Beam tool 204 is located within main chamber 201. EFEM 206 includes a first loading port 206a and a second loading port 206b. EFEM 206 may include additional loading port(s). First loading port 206a and second loading port 206b receive wafer front opening unified pods (FOUPs) that contain wafers (e.g., semiconductor wafers or wafers made of other material(s)) or samples to be inspected (the terms “wafers” and “samples” may be used interchangeably). A “lot” is a plurality of wafers that may be loaded for processing as a batch.

[0029] One or more robotic arms (not shown) in EFEM 206 may transport the wafers to load / lock chamber 202. Load / lock chamber 202 is connected to a load / lock vacuum pump system (not shown) which removes gas molecules in load / lock chamber 202 to reach a first pressure below the atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) may transport the wafer from load / lock chamber 202 to main chamber 201. Main chamber 201 is connected to a main chamber vacuum pump system (not shown) which removes gas molecules in main chamber 201 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subject to inspection by beam tool 204. Beam tool 204 may be a single-beam system or a multi-beam system.

[0030] A controller 209 is electronically connected to beam tool 204. Controller 209 may be a computer that may execute various controls of CPBI system 200. While controller 209 is shown in Fig. 2 as being outside of the structure that includes main chamber 201, load / lock chamber 202, and EFEM 206, it is appreciated that controller 209 may be a part of the structure.

[0031] In some embodiments, controller 209 may include one or more processors (not shown). A processor may be a generic or specific electronic device capable of manipulating or processing information. For example, the processor may include any combination of any number of a central processing unit (or “CPU”), a graphics processing unit (or “GPU”), an optical processor, a programmable logic controller, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a Programmable Logic Array (PLA), a Programmable Array Logic (PAL), a Generic Array Logic (GAL), a Complex Programmable Logic Device (CPLD), a Field- Programmable Gate Array (FPGA), a System On Chip (SoC), an Application-Specific Integrated Circuit (ASIC), a neural processing unit (NPU), and any type of circuit capable of data processing. The processor may also be a virtual processor that includes one or more processors distributed across multiple machines or devices coupled via a network.

[0032] In some embodiments, controller 209 may further include one or more memories (not shown). A memory may be a generic or specific electronic device capable of storing codes and data accessible by the processor (e.g., via a bus). For example, the memory may include any combination of any number of a random-access memory (RAM), a read-only memory (ROM), an optical disc, a magnetic disk, ahard drive, a solid-state drive, a flash drive, a security digital (SD) card, a memory stick, a compact flash (CF) card, or any type of storage device. The codes may include an operating system (OS) and one or more application programs (or “apps”) for specific tasks. The memory may also be a virtual memory that includes one or more memories distributed across multiple machines or devices coupled via a network.

[0033] Fig. 3 illustrates an example imaging system 300 consistent with some embodiments of the present disclosure. Beam tool 204 of Fig. 3 may be configured for use in CPBI system 200. Beam tool 204 may be a single beam apparatus or a multi-beam apparatus. As shown in Fig. 3, beam tool 204 includes a motorized sample stage 301, and a wafer holder 302 supported by motorized sample stage 301 to hold a wafer 303 to be inspected. Beam tool 204 further includes an objective lens assembly 304, a charged-particle detector 306 (which includes charged-particle sensor surfaces 306a and 306b), an objective aperture 308, a condenser lens 310, a beam limit aperture 312, a gun aperture 314, an anode 316, and a cathode 318. Objective lens assembly 304, in some embodiments, may include a modified swing objective retarding immersion lens (SORIL), which includes a pole piece 304a, a control electrode 304b, a deflector 304c, and an exciting coil 304d. Beam tool 204 may additionally include an Energy Dispersive X-ray Spectrometer (EDS) detector (not shown) to characterize the materials on wafer 303.

[0034] A primary charged-particle beam 320 (or simply “primary beam 320”), such as an electron beam, is emitted from cathode 318 by applying an acceleration voltage between anode 316 and cathode 318. Primary beam 320 passes through gun aperture 314 and beam limit aperture 312, both of which may determine the size of charged-particle beam entering condenser lens 310, which resides below beam limit aperture 312. Condenser lens 310 focuses primary beam 320 before the beam enters objective aperture 308 to set the size of the charged-particle beam before entering objective lens assembly 304. Deflector 304c deflects primary beam 320 to facilitate beam scanning on the wafer. For example, in a scanning process, deflector 304c may be controlled to deflect primary beam 320 sequentially onto different locations of top surface of wafer 303 at different time points, to provide data for image reconstruction for different parts of wafer 303. Moreover, deflector 304c may also be controlled to deflect primary beam 320 onto different sides of wafer 303 at a particular location, at different time points, to provide data for stereo image reconstruction of the wafer structure at that location. Further, in some embodiments, anode 316 and cathode 318 may generate multiple primary beams 320, and beam tool 204 may include a plurality of deflectors 304c to project the multiple primary beams 320 to different parts / sides of the wafer at the same time, to provide data for image reconstruction for different parts of wafer 303.

[0035] Exciting coil 304d and pole piece 304a generate a magnetic field that begins at one end of pole piece 304a and terminates at the other end of pole piece 304a. A part of wafer 303 being scanned by primary beam 320 may be immersed in the magnetic field and may be electrically charged, which, in turn, creates an electric field. The electric field reduces the energy of impinging primary beam 320 nearthe surface of wafer 303 before it collides with wafer 303. Control electrode 304b, being electrically isolated from pole piece 304a, controls an electric field on wafer 303 to prevent micro-arching of wafer 303 and to ensure proper beam focus.

[0036] A secondary charged-particle beam 322 (or “secondary beam 322”), such as secondary electron beams, may be emitted from the part of wafer 303 upon receiving primary beam 320. Secondary beam 322 may form a beam spot on sensor surfaces 306a and 306b of charged-particle detector 306. Charged- particle detector 306 may generate a signal (e.g., a voltage, a current, or the like) that represents an intensity of the beam spot and provide the signal to an image processing system 350. The intensity of secondary beam 322, and the resultant beam spot, may vary according to the external or internal structure of wafer 303. Moreover, as discussed above, primary beam 320 may be projected onto different locations of the top surface of the wafer or different sides of the wafer at a particular location, to generate secondary beams 322 (and the resultant beam spot) of different intensities. Therefore, by mapping the intensities of the beam spots with the locations of wafer 303, the processing system may reconstruct an image that reflects the internal or surface structures of wafer 303.

[0037] Imaging system 300 may be used for inspecting a wafer 303 on motorized sample stage 301 and includes beam tool 204, as discussed above. Imaging system 300 may also include an image processing system 350 that includes an image acquirer 360, storage 370, and controller 209. Image acquirer 360 may include one or more processors. For example, image acquirer 360 may include a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, and the like, or a combination thereof. Image acquirer 360 may connect with a detector 306 of beam tool 204 through a medium such as an electrical conductor, optical fiber cable, portable storage media, IR, Bluetooth, internet, wireless network, wireless radio, or a combination thereof. Image acquirer 360 may receive a signal from detector 306 and may construct an image. Image acquirer 360 may thus acquire images of wafer 303. Image acquirer 360 may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, and the like. Image acquirer 360 may perform adjustments of brightness and contrast, or the like of acquired images. Storage 370 may be a storage medium such as a hard disk, cloud storage, random access memory (RAM), other types of computer readable memory, and the like. Storage 370 may be coupled with image acquirer 360 and may be used for saving scanned raw image data as original images, post-processed images, or other images assisting of the processing. Image acquirer 360 and storage 370 may be connected to controller 209. In some embodiments, image acquirer 360, storage 370, and controller 209 may be integrated together as one control unit.

[0038] In some embodiments, image acquirer 360 may acquire one or more images of a sample based on an imaging signal received from detector 306. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image including a plurality of imaging areas. The single image may be stored in storage 370. The single image may bean original image that may be divided into a plurality of regions. Each of the regions may include one imaging area containing a feature of wafer 303.

[0039] Consistent with some embodiments of this disclosure, a computer-implemented method of training a machine learning model for defect detection may include obtaining training data that includes an inspection image of a fabricated integrated circuit (IC) and design layout data of the IC. The obtaining operation, as used herein, may refer to accepting, taking in, admitting, gaining, acquiring, retrieving, receiving, reading, accessing, collecting, or any operation for inputting data. An inspection image, as used herein, may refer to an image generated as a result of an inspection process performed by a charged-particle inspection apparatus (e.g., system 200 of Fig. 2 or system 300 of Fig. 3). For example, an inspection image may be an SCPM image generated by image processing system 350 in Fig. 3. A fabricated IC in this disclosure may refer to an IC manufactured on a sample (e.g., a wafer) in a semiconductor manufacturing process (e.g., a photolithography process). For example, the fabricated IC may be manufactured in a die of the sample. Design layout data of an IC, as used herein, may refer to data representing a designed layout of the IC. In some embodiments, the design layout data may include a design layout file in a GDS format (e.g., a GDS layout file). The design layout file may be visualized (also referred to as “rendered”) to be a 2D image (referred to as a “rendered image” herein) that presents the layout of the IC. The rendered image may include various geometric features (e.g., vertices, edges, corners, polygons, holes, bridges, vias, or the like) of the IC.

[0040] In some embodiments, the design layout data of the IC may include an image (e.g., the rendered image) rendered based on GDS clip data of the IC. GDS clip data of an IC, as used herein, may refer to design layout data of the IC that is to be fabricated in a die, which is of the GDS format. In some embodiments, the design layout data of the IC may include only a design layout file (e.g., the GDS clip data) of the IC. In some embodiments, the design layout data of the IC may include only the rendered image of the IC. In some embodiments, the design layout data of the IC may include only a golden image of the IC. In some embodiments, the design layout data may include any combination of the design layout file, the golden image, and the rendered image of the IC.

[0041] Fig. 4 illustrates a schematic diagram of an example multi-beam beam tool 204 (also referred to herein as apparatus 204) and an image processing system 490 that may be configured for use in EBI system 100 (Fig. 2), consistent with embodiments of the present disclosure.

[0042] Beam tool 204 comprises a charged-particle source 402, a gun aperture 404, a condenser lens 406, a primary charged-particle beam 410 emitted from charged-particle source 402, a source conversion unit 412, a plurality of beamlets 414, 416, and 418 of primary charged-particle beam 410, a primary projection optical system 420, a motorized wafer stage 480, a wafer holder 482, multiple secondary charged-particle beams 436, 438, and 440, a secondary optical system 442, and a charged- particle detection device 444. Primary projection optical system 420 can comprise a beam separator 422, a deflection scanning unit 426, and an objective lens 428. Charged-particle detection device 444 can comprise detection sub-regions 446, 448, and 450.

[0043] Charged-particle source 402, gun aperture 404, condenser lens 406, source conversion unit 412, beam separator 422, deflection scanning unit 426, and objective lens 428 can be aligned with a primary optical axis 460 of apparatus 204. Secondary optical system 442 and charged-particle detection device 444 can be aligned with a secondary optical axis 452 of apparatus 204.

[0044] Charged-particle source 402 can emit one or more charged particles, such as electrons, protons, ions, muons, or any other particle carrying electric charges. In some embodiments, charged-particle source 402 may be an electron source. For example, charged-particle source 402 may include a cathode, an extractor, or an anode, wherein primary electrons can be emitted from the cathode and extracted or accelerated to form primary charged-particle beam 410 (in this case, a primary electron beam) with a crossover (virtual or real) 408. For ease of explanation without causing ambiguity, electrons are used as examples in some of the descriptions herein. However, it should be noted that any charged particle may be used in any embodiment of this disclosure, not limited to electrons. Primary charged-particle beam 410 can be visualized as being emitted from crossover 408. Gun aperture 404 can block off peripheral charged particles of primary charged-particle beam 410 to reduce Coulomb effect. The Coulomb effect may cause an increase in size of probe spots.

[0045] Source conversion unit 412 can comprise an array of image-forming elements and an array of beam-limit apertures. The array of image-forming elements can comprise an array of micro-deflectors or micro-lenses. The array of image-forming elements can form a plurality of parallel images (virtual or real) of crossover 408 with a plurality of beamlets 414, 416, and 418 of primary charged-particle beam 410. The array of beam-limit apertures can limit the plurality of beamlets 414, 416, and 418. While three beamlets 414, 416, and 418 are shown in Fig. 4, embodiments of the present disclosure are not so limited. For example, in some embodiments, the apparatus 204 may be configured to generate a first number of beamlets. In some embodiments, the first number of beamlets may be in a range from 1 to 1000. In some embodiments, the first number of beamlets may be in a range from 200-500. In some embodiments, an apparatus 204 may generate 400 beamlets.

[0046] Condenser lens 406 can focus primary charged-particle beam 410. The electric currents of beamlets 414, 416, and 418 downstream of source conversion unit 412 can be varied by adjusting the focusing power of condenser lens 406 or by changing the radial sizes of the corresponding beam-limit apertures within the array of beam-limit apertures. Objective lens 428 can focus beamlets 414, 416, and 418 onto a wafer 430 for imaging, and can form a plurality of probe spots 470, 472, and 474 on a surface of wafer 430.

[0047] Beam separator 422 can be a beam separator of Wien filter type generating an electrostatic dipole field and a magnetic dipole field. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on a charged particle (e.g., an electron) of beamlets 414, 416, and 418 can be substantially equal in magnitude and opposite in a direction to the force exerted on the charged particle by magnetic dipole field. Beamlets 414, 416, and 418 can, therefore, pass straight through beam separator 422 with zero deflection angle. However, the total dispersion of beamlets 414, 416, and 418generated by beam separator 422 can also be non-zero. Beam separator 422 can separate secondary charged-particle beams 436, 438, and 440 from beamlets 414, 416, and 418 and direct secondary charged-particle beams 436, 438, and 440 towards secondary optical system 442.

[0048] Deflection scanning unit 426 can deflect beamlets 414, 416, and 418 to scan probe spots 470, 472, and 474 over a surface area of wafer 430. In response to the incidence of beamlets 414, 416, and 418 at probe spots 470, 472, and 474, secondary charged-particle beams 436, 438, and 440 may be emitted from wafer 430. Secondary charged-particle beams 436, 438, and 440 may comprise charged particles (e.g., electrons) with a distribution of energies. For example, secondary charged-particle beams 436, 438, and 440 may be secondary electron beams including secondary electrons (energies < 50 eV) and backscattered electrons (energies between 50 eV and landing energies of beamlets 414, 416, and 418). Secondary optical system 442 can focus secondary charged-particle beams 436, 438, and 440 onto detection sub-regions 446, 448, and 450 of charged-particle detection device 444. Detection sub-regions 446, 448, and 450 may be configured to detect corresponding secondary charged-particle beams 436, 438, and 440 and generate corresponding signals (e.g., voltage, current, or the like) used to reconstruct an inspection image of structures on or underneath the surface area of wafer 430.

[0049] The generated signals may represent intensities of secondary charged-particle beams 436, 438, and 440 and may be provided to image processing system 490 that is in communication with charged- particle detection device 444, primary projection optical system 420, and motorized wafer stage 480. The movement speed of motorized wafer stage 480 may be synchronized and coordinated with the beam deflections controlled by deflection scanning unit 426, such that the movement of the scan probe spots (e.g., scan probe spots 470, 472, and 474) may orderly cover regions of interest on the wafer 430. The parameters of such synchronization and coordination may be adjusted to adapt to different materials of wafer 430. For example, different materials of wafer 430 may have different resistance-capacitance characteristics that may cause different signal sensitivities to the movement of the scan probe spots.

[0050] The intensity of secondary charged-particle beams 436, 438, and 440 may vary according to the external or internal structure of wafer 430, and thus may indicate whether wafer 430 includes defects. Moreover, as discussed above, beamlets 414, 416, and 418 may be projected onto different locations of the top surface of wafer 430, or different sides of local structures of wafer 430, to generate secondary charged-particle beams 436, 438, and 440 that may have different intensities. Therefore, by mapping the intensity of secondary charged-particle beams 436, 438, and 440 with the areas of wafer 430, image processing system 490 may reconstruct an image that reflects the characteristics of internal or external structures of wafer 430.

[0051] In some embodiments, image processing system 490 may include an image acquirer 492, a storage 494, and a controller 496. Image acquirer 492 may comprise one or more processors. For example, image acquirer 492 may comprise a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, or the like, or a combination thereof. Image acquirer 492 may be communicatively coupled to charged-particle detection device 444 of beam tool 204through a medium such as an electric conductor, optical fiber cable, portable storage media, IR, Bluetooth, internet, wireless network, wireless radio, or a combination thereof. In some embodiments, image acquirer 492 may receive a signal from charged-particle detection device 444 and may construct an image. Image acquirer 492 may thus acquire inspection images of wafer 430. Image acquirer 492 may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, or the like. Image acquirer 492 may be configured to perform adjustments of brightness and contrast of acquired images. In some embodiments, storage 494 may be a storage medium such as a hard disk, flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, or the like. Storage 494 may be coupled with image acquirer 492 and may be used for saving scanned raw image data as original images, and post-processed images. Image acquirer 492 and storage 494 may be connected to controller 496. In some embodiments, image acquirer 492, storage 494, and controller 496 may be integrated together as one control unit.

[0052] In some embodiments, image acquirer 492 may acquire one or more inspection images of a wafer based on an imaging signal received from charged-particle detection device 444. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image comprising a plurality of imaging areas. The single image may be stored in storage 494. The single image may be an original image that may be divided into a plurality of regions. Each of the regions may comprise one imaging area containing a feature of wafer 430. The acquired images may comprise multiple images of a single imaging area of wafer 430 sampled multiple times over a time sequence. The multiple images may be stored in storage 494. In some embodiments, image processing system 490 may be configured to perform image processing steps with the multiple images of the same location of wafer 430.

[0053] In some embodiments, image processing system 490 may include measurement circuits (e.g., analog-to-digital converters) to obtain a distribution of the detected secondary charged particles (e.g., secondary electrons). The charged-particle distribution data collected during a detection time window, in combination with corresponding scan path data of beamlets 414, 416, and 418 incident on the wafer surface, can be used to reconstruct images of the wafer structures under inspection. The reconstructed images can be used to reveal various features of the internal or external structures of wafer 430, and thereby can be used to reveal any defects that may exist in the wafer.

[0054] In some embodiments, the charged particles may be electrons. When electrons of primary charged-particle beam 410 are projected onto a surface of wafer 430 (e.g., probe spots 470, 472, and 474), the electrons of primary charged-particle beam 410 may penetrate the surface of wafer 430 for a certain depth, interacting with particles of wafer 430. Some electrons of primary charged-particle beam 410 may elastically interact with (e.g., in the form of elastic scattering or collision) the materials of wafer 430 and may be reflected or recoiled out of the surface of wafer 430. An elastic interaction conserves the total kinetic energies of the bodies (e.g., electrons of primary charged-particle beam 410) of the interaction, in which the kinetic energy of the interacting bodies does not convert to other formsof energy (e.g., heat, electromagnetic energy, or the like). Such reflected electrons generated from elastic interaction may be referred to as backscattered electrons (BSEs). Some electrons of primary charged-particle beam 410 may inelastically interact with (e.g., in the form of inelastic scattering or collision) the materials of wafer 430. An inelastic interaction does not conserve the total kinetic energies of the bodies of the interaction, in which some or all of the kinetic energy of the interacting bodies convert to other forms of energy. For example, through the inelastic interaction, the kinetic energy of some electrons of primary charged-particle beam 410 may cause electron excitation and transition of atoms of the materials. Such inelastic interaction may also generate electrons exiting the surface of wafer 430, which may be referred to as secondary electrons (SEs). Yield or emission rates of BSEs and SEs depend on, e.g., the material under inspection and the landing energy of the electrons of primary charged-particle beam 410 landing on the surface of the material, among others. The energy of the electrons of primary charged-particle beam 410 may be imparted in part by its acceleration voltage (e.g., the acceleration voltage between the anode and cathode of charged-particle source 402 in Fig. 4). The quantity of BSEs and SEs may be more or fewer (or even the same) than the injected electrons of primary charged-particle beam 410.

[0055] Fig. 5 is a block diagram of an example server 500, consistent with some embodiments of the disclosure. As shown in Fig. 5, server 500 can include processor 502, which can be any type of circuitry capable of manipulating or processing information. For example, processor 502 can include any combination of any number of a central processing unit (“CPU”), a graphics processing unit (“GPU”), a neural processing unit (“NPU”), a microcontroller unit (“MCU”), an optical processor, a programmable logic controller, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a Programmable Logic Array (PLA), a Programmable Array Logic (PAL), a Generic Array Logic (GAL), a Complex Programmable Logic Device (CPLD), a Field- Programmable Gate Array (FPGA), a System On Chip (SoC), an Application-Specific Integrated Circuit (ASIC), or the like. In some embodiments, processor 502 can also be a set of processors grouped as a single logical component. For example, as shown in Fig. 5, processor 502 can include multiple processors, including processor 502a, processor 502b, and processor 502n.

[0056] Server 500 can also include memory 504 configured to store data (e.g., a set of instructions, computer codes, intermediate data, or the like). For example, as shown in Fig. 5, the stored data can include program instructions and data for processing. Processor 502 can access the program instructions and data for processing (e.g., via bus 510), and execute the program instructions to perform an operation or manipulation on the data for processing. Memory 504 can include a high-speed random-access storage device or a non-volatile storage device. In some embodiments, memory 504 can include any combination of any number of a random-access memory (RAM), a read-only memory (ROM), an optical disc, a magnetic disk, a hard drive, a solid-state drive, a flash drive, a security digital (SD) card, a memory stick, a compact flash (CF) card, or the like. Memory 504 can also be a group of memories (not shown in Fig. 5) grouped as a single logical component.

[0057] Bus 510 can be a communication device that transfers data between components inside server 500, such as an internal bus (e.g., a CPU-memory bus), an external bus (e.g., a universal serial bus port, a peripheral component interconnect express port), or the like.

[0058] For ease of explanation without causing ambiguity, processor 502 and other data processing circuits are collectively referred to as a “data processing circuit” in this disclosure. The data processing circuit can be implemented entirely as hardware, or as a combination of software, hardware, or firmware. In addition, the data processing circuit can be a single independent module or can be combined entirely or partially into any other component of server 500.

[0059] Server 500 can further include network interface 506 to provide wired or wireless communication with a network (e.g., the Internet, an intranet, a local area network, a mobile communications network, or the like). In some embodiments, network interface 506 can include any combination of any number of a network interface controller (NIC), a radio frequency (RF) module, a transponder, a transceiver, a modem, a router, a gateway, a wired network adapter, a wireless network adapter, a Bluetooth adapter, an infrared adapter, a near-field communication (“NFC”) adapter, a cellular network chip, or the like.

[0060] In some embodiments, optionally, server 500 can further include peripheral interface 508 to provide a connection to one or more peripheral devices. As shown in Fig. 5, the peripheral device can include, but is not limited to, a cursor control device (e.g., a mouse, a touchpad, or a touchscreen), a keyboard, a display (e.g., a cathode -ray tube display, a liquid crystal display, or a light-emitting diode display), a video input device (e.g., a camera or an input interface coupled to a video archive), or the like.

[0061] To reduce the total cycle time of the wafer print check process, in-parallel inspection between full field inspection and repeater defect detection is performed. When part of the full field inspection is completed, a MBI tool (e.g., multi-beam inspection tool of Fig. 4) saves the inspection results that are accessed by a control server from the MBI tool that monitors the results files on the MBI tool. For example, the full field inspection may be divided into multiple “zones,” where each zone is a subsection of the full field. For example, a zone may be a predetermined percentage of the full field (e.g., 5% or 10%) or may have a predetermined size (e.g., 5mm x 5mm). It is noted that the above examples for the sizes of a zone are merely exemplary and that other sizes for a zone are possible and are contemplated within the scope of the present disclosure. In some embodiments, the size of a zone may be optimized to help reduce the overhead in the repeater detection tool. For example, the overhead may result from moving a sample stage to move the wafer to enable the repeater detection tool to inspect the same zone in the different fields.

[0062] After the zone is scanned by the MBI tool, the results file for the zone is then accessed by a control server (e.g., server 500 of Fig. 5), which forwards the results file to a repeater detection tool (e.g., a single beam inspection (SBI) tool, such as the single -beam inspection tool of Fig. 3) to start repeater detection jobs. In some embodiments, two control wafers produced with the same process arepre-loaded onto the MBI tool and the SBI tool. As used herein, the term “control wafer” is a wafer containing simple film stacks printed on the wafer with the mask to be inspected. The control wafer is used for inspection purposes only. Because the process to produce each control wafer is the same, any mask-based defects in the two wafers would be the same (i.e., there would be defects in the same locations on both wafers). Using control wafers enables potential mask defect detection and correction prior to the start of production. Correcting mask defects prior to the start of or during production helps to improve the overall yield of the manufacturing process. The same processes described herein may be applied to production wafers for defect detection.

[0063] The SBI tool is configured to accept defect sampling locations on the fly while performing repeater defect detection to reduce the overhead time to re-start the inspection job when receiving different defect sampling locations. A user of the system may configure the system on how to split the full field inspection jobs and how many defects to report to the defect candidate list. For example, this configuration may be performed via a user interface for the system, such as a “recipe” configuration. Each zone results defect list should not be too large such that the SBI tool cannot finish the repeater defect detection before receiving the data for the next zone of the full field inspection. The defect list should also not be too small such that the SBI tool finishes the repeater detection before the results for the next zone of the full field inspection are received.

[0064] For example, the SBI tool may receive a first list of locations to inspect (e.g., a first zone) and may receive a second list of locations to inspect (e.g., a second zone) while the first list of locations is still being searched. In some embodiments, a size of the list of locations to inspect (e.g., in terms of area and not a number of potential defects) may be set such that the SBI tool can finish searching the first list just before the second list is received. Doing so would help to optimize the total cycle time.

[0065] The distribution of inspection jobs between the MBI tool and the SBI tool is not limited to splitting one full field on one MBI tool and one SBI tool. The principles of operation described herein can also support splitting the inspection job among multiple MBI tools and multiple SBI tools, as will be described in further detail elsewhere in this disclosure. By splitting the full field inspection job to multiple MBI tools, it reduces the total cycle time for the wafer print check process. For example, one full field inspection on one MBI tool may take two hours. If the job is split between two MBI tools, with each MBI tool inspecting one-half of the full field, the total full field inspection time is one hour. Each inspection job on each MBI tool may be further split as described in the flow above (e.g., with each MBI tool inspecting one or more zones) to enable in-parallel repeater defect detection on multiple SBI tools.

[0066] With such a distributed inspection system, a wafer print check process using CPBI tools (e.g., MBI tools and SBI tools) may be faster than bright field optical inspection tools by reducing the total cycle time in addition to providing a better defect capturing sensitivity. For example, in a traditional sequential flow, if one MBI tool can inspect a full field in two hours, and it sends 1000 defect candidatesfor defect repeater detection that takes another 0.5 hours, the total cycle time is 2.5 hours for 1000 verified defects.

[0067] In the in-parallel flow, one MBI tool can inspect a full field in two hours, while sending a defect list to the SBI tool every two minutes. The SBI tool starts the verification job two minutes after the MBI tool starts the full field inspection. Every SBI verification job is also completed in two minutes. Then the full wafer print check process is finished two minutes after the full field inspection is finished, such that the total cycle time is two hours and two minutes, compared to a total cycle time of 2.5 hours for the sequential flow. As the SBI tool can inspect more defects during the MBI inspection job without adding more cycle time, the SBI tool can verify more than 10000 repeater defects, for example. By allowing the full field inspection to report more defect candidates to the SBI tool, the inspection throughput on the MBI tool may also be improved.

[0068] The overall cycle time for the wafer print check process is important and it is desirable to process wafers as fast as possible. The in-parallel inspection process described herein saves time (i.e., the overall cycle time is lower) and also permits more time for repeater detection (i.e., it may be possible to inspect more potential defect locations while staying within the overall cycle time budget).

[0069] Fig. 6 is a flow diagram of an in-parallel repeater defect detection process 600, consistent with embodiments of the present disclosure. The process 600 is performed by a full field inspection tool 602 and a repeater defect detection tool 604. The full field inspection tool 602 inspects a zone of the full field. As described elsewhere in this disclosure, a zone may be defined based on a portion of the full field, e.g., a percentage of the full field or by a predetermined size that is smaller than the full field. After inspecting a first zone of the full field, the full field inspection tool 602 generates a list of defect candidates 606a, which is sent to the repeater defect detection tool 604 for repeater defect verification. After each zone is inspected by the full field inspection tool 602, a list of defect candidates is sent to the repeater defect detection tool 604 until all zones of the full field have been inspected (represented in Fig. 6 by list of defect candidates 606n).

[0070] Fig. 7 is a schematic diagram of a system 700 for performing an in-parallel repeater defect detection process, consistent with embodiments of the present disclosure. The system 700 includes an MBI tool 702 (e.g., multi-beam inspection tool of Fig. 4), an SBI tool 704 (e.g., single-beam inspection tool of Fig. 3), and a job control and data exchange server 706 (e.g., server 500 of Fig. 5).

[0071] The MBI tool 702 performs a full field inspection on a first wafer (wafer 1) 708. As shown in Fig. 7, the full field inspection includes the rectangular area of wafer 708. It is noted that the location of the area on the wafer 708 is exemplary and that any area of the wafer 708 may be inspected by the full field inspection. The MBI tool 702 generates a list of defect candidates 710 for each zone of the full field inspection, lists 710a-710n. As described elsewhere in this disclosure, a zone is a portion of the full field inspection.

[0072] As each list 710a-710n is generated by the MBI tool 702, the server 706 accesses the list 710 from the MBI tool 702. In some embodiments, the MBI tool 702 may upload the list 710 to the server706, for example, when the MBI tool 702 finishes inspecting a zone. The server 706 may temporarily store the list 710 before sending the list 710 to the SBI tool 704 for repeater defect detection. In some embodiments, the server 706 may delay sending the list 710 to the SBI tool 704 to control the timing of the repeater defect detection process.

[0073] The SBI tool 704 inspects a second wafer (wafer 2) 712. As shown in Fig. 7, the wafer 712 has multiple fields that will be inspected by the SBI tool 704 as shown by the rectangular areas. The SBI tool 704 inspects each field based on the list 710 received from the server 706. After completing the repeater defect detection, the SBI tool 704 provides a summary of repeater defects and saves the summary on a computer associated with the SBI tool 704 or uploads the summary to the server 706 (shown in Fig. 7 as optional summary 714). A user of the system 700 may access the results and monitor the repeater defects and take appropriate actions on the masks.

[0074] Fig. 8 is a schematic diagram of another system 800 for performing an in-parallel repeater defect detection process, consistent with embodiments of the present disclosure. The system 800 includes a plurality of MBI tools 802a-802n (e.g., multi-beam inspection tool of Fig. 4), a plurality of SBI tools 804a-804m (e.g., single-beam inspection tool of Fig. 3), and a job control and data exchange server 806 (e.g., server 500 of Fig. 5).

[0075] Each MBI tool 802a-802n performs a part of the full field inspection on a relevant wafer (wafer 1 to wafer N) 8O8a-8O8n. As shown in Fig. 8, the full field inspection includes the rectangular area of wafer 8O8a-8O8n. It is noted that the location of the area on the wafer 8O8a-8O8n is exemplary and that any area of the wafer 8O8a-8O8n may be inspected by the MBI tools. Each MBI tool 802a-802n generates a list of defect candidates 810 for each zone of the full field inspection, lists 810a-810n. As described elsewhere in this disclosure, a zone is a portion of the full field inspection.

[0076] As each list 810a-810n is generated by each MBI tool 802a-802n, the server 806 accesses the list 810 from each MBI tool 802a-802n. In some embodiments, each MBI tool 802a-802n may upload the list 810 to the server 806, for example, when each MBI tool 802a-802n finishes inspecting a zone. The server 806 may delay sending the list 810 to each SBI tool 804a-804m to control the timing of the repeater defect detection process. In some embodiments, the server 806 may store the list 810 to control the timing of the repeater defect detection performed by each SBI tool 804a-804m.

[0077] Each SBI tool 804a-804m inspects another set of wafers (wafer 3 to wafer M) 812a-812m. As shown in Fig. 8, each wafer 812a-812m has multiple fields that will be inspected by the respective SBI tool 804a-804m as shown by the rectangular areas. Each SBI tool 804a-804m inspects each field based on the list 810 received from the server 806. After completing the repeater defect detection, each SBI tool 804a-804m provides a summary 814 to the server 806 including whether any repeated defects were detected. The server 806 performs the aggregation analysis and reports all mask defects reported by each SBI tool 804a-804m.

[0078] In the distributed inspection system as shown in Fig. 7 and Fig. 8, the server 706, 806 manages how data will be ready from the MBI tool and coordinates sending the data to the SBI tool. The serveraccesses the data from the MBI tool. In some embodiments, the server can detect if the data is ready from the MBI tool, and then accesses the data. In some embodiments, the server may also be configured to upload the data to the SBI tool. In some embodiments, the SBI tool can store the data until it is ready to scan the next batch of defect candidates. The server may also be used for timing control in the system. The server attempts to coordinate the timing such that a first list of defect candidates is sent to the SBI tool (and repeater defect scanning is completed by the SBI tool) before a second list of defect candidates is accessed from the MBI tool. This coordination may help with overall cycle time optimization.

[0079] With multiple MBI tools (such as shown in Fig. 8), each MBI tool inspects the same field on its wafer but can inspect different zones of the field such that inspecting the full field may be divided among the multiple MBI tools. Doing so can help to reduce the total cycle time for the wafer print check process because multiple zones are being inspected at the same time. Each SBI tool receives a subset of the zones to search. Any SBI tool in the system can search any zones based on the defect candidate list received by the SBI tool, resulting in a flexible system-wide arrangement. It is noted that there does not have to be a one-to-one correspondence between each MBI tool and each SBI tool. For example, there may be multiple MBI tools and one SBI tool, one MBI tool and multiple SBI tools, or multiple MBI tools and multiple SBI tools in the system.

[0080] Fig. 9 is a flowchart of an example method 900 for a distributed wafer print check process, consistent with embodiments of the present disclosure. In some embodiments, the method 900 may be performed by image processing system 250 of Fig. 2, by the system 700 of Fig. 7, or by the system 800 of Fig. 8.

[0081] At step 902, zones of a full field of a wafer are inspected in a first tool. For example, the first tool may be an MBI tool such as MBI tool 702 shown in Fig. 7. The first tool generates a list of defect candidates for each zone of the full field inspection. As described elsewhere in this disclosure, a zone is a portion of the full field inspection.

[0082] At step 904, a control server accesses inspection results for one zone from the first tool. For example, the control server may be a server such as server 706 shown in Fig. 7. The server may be configured such that it periodically polls the first tool to access the inspection results for a zone. For example, if it is known that the first tool can inspect one zone in two minutes, then the server may be configured to access the inspection results from the first tool every two minutes. In some embodiments, the first tool may be configured to upload the inspection results for a zone to the server once the zone has been inspected.

[0083] At step 906, the control server sends the inspection results for the zones to a second tool for repeater defect detection. For example, the second tool may be an SBI tool such as SBI tool 704 shown in Fig. 7. The second tool is configured to perform repeater defect detection as described elsewhere in this disclosure.

[0084] At step 908, a determination is made whether all zones of the full field have been inspected for repeater defect detection by the second tool. If all zones of the full field have not been inspected (step908, “no” branch), then at step 904, the server accesses the inspection results for another zone from the first tool. If all zones of the full field have been inspected (step 908, “yes” branch), then at step 910, the second tool outputs the results of the repeater defect detection process to the server.

[0085] A non-transitory computer readable medium may be provided that stores instructions for a processor of a controller (e.g., controller 209 of FIG. 2) to carry out, among other things, image inspection, image acquisition, stage positioning, beam focusing, electric field adjustment, beam bending, condenser lens adjusting, activating charged particle source, beam deflecting, and operations of systems 700 and 800 and method 900. Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a Compact Disc Read Only Memory (CD-ROM), any other optical data storage medium, any physical medium with patterns of holes, a Random Access Memory (RAM), a Programmable Read Only Memory (PROM), and Erasable Programmable Read Only Memory (EPROM), a FLASH- EPROM or any other flash memory, Non-Volatile Random Access Memory (NVRAM), a cache, a register, any other memory chip or cartridge, and networked versions of the same.

[0086] The embodiments may further be described using the following clauses:1. A method for performing a distributed wafer print check, comprising: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; providing the defect locations of the zone of the first wafer to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein: the zone of the first wafer is in a same location as the zone of the second wafer; and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.2. The method of clause 1 , wherein the first inspection tool is a multi-beam inspection tool.3. The method of clauses 1 or 2, wherein the second inspection tool is a single beam inspection tool.4. The method of any one of clauses 1-3, wherein the full field is an area of the first wafer that the first inspection tool can inspect at one time.5. The method of any one of clauses 1-4, wherein the zone is a portion of the full field.6. The method of clause 5, wherein the zone is a predetermined percentage of the full field.7. The method of clause 5, wherein the zone is a predetermined size, the predetermined size being smaller than the full field.8. The method of any one of clauses 1-7, wherein the receiving includes accessing the defect locations of the zone of the first wafer from the first inspection tool by the server.9. The method of any one of clauses 1-8, wherein the receiving includes sending, by the first inspection tool, the defect locations of the zone of the first wafer to the server.10. The method of any one of clauses 1-9, further comprising:receiving results by the server from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.11. A system for performing a distributed wafer print check, comprising: a plurality of first inspection tools, wherein each of the plurality of first inspection tools is configured to: receive a first wafer; inspect a zone of a full field of the first wafer; and determine defect locations in the zone of the first wafer; a server communicatively coupled with the plurality of first inspection tools and a plurality of second inspection tools, wherein the server is configured to: receive the defect locations of the zone of the first wafer from each of the plurality of first inspection tools; and send the defect locations of the zone of the first wafer to one of the plurality of second inspection tools; and each of the plurality of second inspection tools is configured to: receive a second wafer; determine whether the defect locations of the zone of the first wafer repeat in a zone of the second wafer, wherein the zone of the first wafer is in a same location as the zone of the second wafer; and inspect the zone of the second wafer while each of the plurality of first inspection tools inspects another zone of the first wafer.12. The system of clause 11, wherein each of the plurality of first inspection tools is configured to inspect a different zone of the full field of the first wafer.13. The system of clauses 11 or 12, wherein each of the plurality of first inspection tools is a multibeam inspection tool.14. The system of any one of clauses 11-13, wherein each of the plurality of second inspection tools is a single beam inspection tool.15. The system of any one of clauses 11-14, wherein the server is further configured to access the defect locations of the zone of the first wafer from each of the plurality of first inspection tools.16. The system of any one of clauses 11-15, wherein each of the plurality of first inspection tools is further configured to send the defect locations of the zone of the first wafer to the server.17. The system of any one of clauses 11-16, wherein the server is further configured to receive results from each of the plurality of second inspection tools, the results indicating whether the second wafer contained defects in a same location as on the first wafer.18. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for performing a distributed wafer print check, the operations comprising:inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; receiving the defect locations of the zone of the first wafer from the first inspection tool by a server; sending the defect locations of the zone of the first wafer from the server to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein: the zone of the first wafer is in a same location as the zone of the second wafer; and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.19. The non-transitory computer readable medium of clause 18, wherein: the first inspection tool is a multi-beam inspection tool; and the second inspection tool is a single beam inspection tool.20. The non-transitory computer readable medium of clauses 18 or 19, wherein the operations further comprise: receiving results by the server from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.21. A method for performing a distributed wafer print check, comprising: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; receiving the defect locations of the zone of the first wafer from the first inspection tool by a server; sending the defect locations of the zone of the first wafer from the server to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein: the zone of the first wafer is in a same location as the zone of the second wafer; and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.22. The method of clause 21, wherein the first inspection tool is a multi-beam inspection tool.23. The method of clauses 21 or 22, wherein the second inspection tool is a single beam inspection tool.24. The method of any one of clauses 21-23, wherein the full field is an area of the first wafer that the first inspection tool can inspect at one time.25. The method of any one of clauses 21-24, wherein the zone is a portion of the full field.26. The method of clause 25, wherein the zone is a predetermined percentage of the full field.27. The method of clause 25, wherein the zone is a predetermined size, the predetermined size being smaller than the full field.28. The method of any one of clauses 21-27, wherein the receiving includes accessing the defect locations of the zone of the first wafer from the first inspection tool by the server.29. The method of any one of clauses 21-28, wherein the receiving includes sending, by the first inspection tool, the defect locations of the zone of the first wafer to the server.30. The method of any one of clauses 21-29, further comprising: receiving results by the server from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.31. A method for performing a distributed wafer print check, comprising: receiving inspection results for a zone of a first wafer from a first inspection tool by a server, the inspection results including defect locations of the zone of the first wafer; sending the defect locations of the zone of the first wafer from the server to a second inspection tool; and receiving inspection results from the second inspection tool at the server, the inspection results indicating whether a second wafer contained defects in a same location as on the first wafer, wherein the second inspection tool inspects a zone of the second wafer while the first inspection tool inspects another zone of the first wafer.32. The method of clause 31, wherein the first wafer and the second wafer are produced by a same process.33. A system for performing a distributed wafer print check, comprising: a first inspection tool configured to: receive a first wafer; inspect a zone of a full field of the first wafer; and determine defect locations in the zone of the first wafer; a server communicatively coupled with the first inspection tool and a second inspection tool, wherein the server is configured to: receive the defect locations of the zone of the first wafer from the first inspection tool; and send the defect locations of the zone of the first wafer to the second inspection tool; and the second inspection tool is configured to: receive a second wafer; determine whether the defect locations of the zone of the first wafer repeat in a zone of the second wafer, wherein the zone of the first wafer is in a same location as the zone of the second wafer; andinspect the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.34. The system of clause 33, wherein the first inspection tool is a multi-beam inspection tool.35. The system of clauses 33 or 34, wherein the second inspection tool is a single beam inspection tool.36. The system of any one of clauses 33-35, wherein the full field is an area of the first wafer that the first inspection tool can inspect at one time.37. The system of any one of clauses 33-36, wherein the zone is a portion of the full field.38. The system of clause 37, wherein the zone is a predetermined percentage of the full field.39. The system of clause 37, wherein the zone is a predetermined size, the predetermined size being smaller than the full field.40. The system of any one of clauses 33-39, wherein the server is further configured to access the defect locations of the zone of the first wafer from the first inspection tool.41. The system of any one of clauses 33-40, wherein the first inspection tool is further configured to send the defect locations of the zone of the first wafer to the server.42. The system of any one of clauses 33-41, wherein the server is further configured to receive results from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.

[0087] Block diagrams in the figures may illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer hardware or software products according to various exemplary embodiments of the present disclosure. In some embodiments, a non-transitory computer-readable medium is provided and can include instructions to perform the functions described in connection with any one or more of Figs. 6-9. In this regard, each block in a schematic diagram may represent certain arithmetical or logical operation processing that may be implemented using hardware such as an electronic circuit. Blocks may also represent a module, segment, or portion of code that comprises one or more executable instructions for implementing the specified logical functions. It should be understood that in some alternative implementations, functions indicated in a block may occur out of the order noted in the figures. For example, two blocks shown in succession may be executed or implemented substantially concurrently, or two blocks may sometimes be executed in reverse order, depending upon the functionality involved. Some blocks may also be omitted. It should also be understood that each block of the block diagrams, and combination of the blocks, may be implemented by special purpose hardware -based systems that perform the specified functions or acts, or by combinations of special purpose hardware and computer instructions.

[0088] It will be appreciated that the embodiments of the present disclosure are not limited to the exact construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The present disclosure has been described in connection with various embodiments, and other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the technologydisclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

CLAIMS1. A method for performing a distributed wafer print check, comprising: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; providing the defect locations of the zone of the first wafer to a second inspection tool; determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein: the zone of the first wafer is in a same location as the zone of the second wafer; and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.

2. The method of claim 1, wherein: the first inspection tool is a multi-beam inspection tool; and the second inspection tool is a single beam inspection tool.

3. The method of claim 1, wherein the full field is an area of the first wafer that the first inspection tool can inspect at one time.

4. The method of claim 1 , wherein the zone is a portion of the full field.

5. The method of claim 1, wherein the receiving includes accessing the defect locations of the zone of the first wafer from the first inspection tool by the server.

6. The method of claim 1 , wherein the receiving includes sending, by the first inspection tool, the defect locations of the zone of the first wafer to the server.

7. The method of claim 1, further comprising: receiving results by the server from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.

8. A system for performing a distributed wafer print check, comprising: a plurality of first inspection tools, wherein each of the plurality of first inspection tools is configured to: receive a first wafer; inspect a zone of a full field of the first wafer; and determine defect locations in the zone of the first wafer;a server communicatively coupled with the plurality of first inspection tools and a plurality of second inspection tools, wherein the server is configured to: receive the defect locations of the zone of the first wafer from each of the plurality of first inspection tools; and send the defect locations of the zone of the first wafer to one of the plurality of second inspection tools; and each of the plurality of second inspection tools is configured to: receive a second wafer; determine whether the defect locations of the zone of the first wafer repeat in a zone of the second wafer, wherein the zone of the first wafer is in a same location as the zone of the second wafer; and inspect the zone of the second wafer while each of the plurality of first inspection tools inspects another zone of the first wafer.

9. The system of claim 8, wherein each of the plurality of first inspection tools is configured to inspect a different zone of the full field of the first wafer.

10. The system of claim 8, wherein: each of the plurality of first inspection tools is a multi-beam inspection tool; and each of the plurality of second inspection tools is a single beam inspection tool.

11. The system of claim 8, wherein each of the plurality of first inspection tools is further configured to send the defect locations of the zone of the first wafer to the server.

12. The system of claim 8, wherein the server is further configured to receive results from each of the plurality of second inspection tools, the results indicating whether the second wafer contained defects in a same location as on the first wafer.

13. A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform operations for performing a distributed wafer print check, the operations comprising: inspecting a zone of a full field of a first wafer by a first inspection tool; determining defect locations in the zone of the first wafer by the first inspection tool; receiving the defect locations of the zone of the first wafer from the first inspection tool by a server; sending the defect locations of the zone of the first wafer from the server to a second inspection tool;determining whether the defect locations of the zone of the first wafer repeat in a zone of a second wafer by the second inspection tool, wherein: the zone of the first wafer is in a same location as the zone of the second wafer; and the second inspection tool inspects the zone of the second wafer while the first inspection tool inspects another zone of the first wafer.

14. The non-transitory computer readable medium of claim 13, wherein: the first inspection tool is a multi-beam inspection tool; and the second inspection tool is a single beam inspection tool.

15. The non-transitory computer readable medium of claim 13, wherein the operations further comprise: receiving results by the server from the second inspection tool, the results indicating whether the second wafer contained defects in a same location as on the first wafer.

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