Multi-pitch SEM overlay marking and stitching area algorithm

Abstract

Improved systems and methods for determining stitch overlay and other metrology parameters in semiconductor fabrication are disclosed. The systems and methods may include acquiring a measurement image of a plurality of overlay marks within a single field of view of an inspection system; individually tuning the image processing algorithm parameters of the measurement image for each overlay mark to determine a measurement value for each overlay mark; and comparing the measurements to determine the suture overlay or other metrology parameters.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Application 63 / 535,179, filed on August 29, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] The embodiments provided herein relate to measurement and inspection techniques, and more particularly to suture overlay inspection using a charged particle beam inspection system. Background Technology

[0003] For example, photolithography apparatus can be used to manufacture integrated circuits (ICs). In this case, a mask or stencil can contain or provide a circuit pattern (“design layout”) corresponding to a single layer of the IC, and this circuit pattern can be transferred onto a target portion (e.g., comprising one or more dies) on a substrate (e.g., a silicon wafer). Misalignment of the pattern on the target portion can significantly impact process yield. Therefore, alignment can be monitored by inspecting the printed wafer during and after the fabrication of each layer in the IC.

[0004] Inspection systems utilizing optical microscopes or charged particle (e.g., electron) beam microscopes (such as scanning electron microscopes (SEM)) can be used to inspect overlays between adjacent exposure fields and overlays between two overlapping fields in different layers on a substrate. For example, when generating device layers with more than one exposure field, stitch overlay marks in a high numerical aperture (NA) EUV system can be provided on either side of the stitch boundary. Summary of the Invention

[0005] Some embodiments of this disclosure provide a non-transitory computer-readable medium. The non-transitory computer-readable medium may store a set of instructions executable by at least one processor of a device. The processor may execute the instructions to cause the device to perform operations, including: acquiring a measurement image of a region on a substrate, the region including a first set of markings and a second set of markings; performing a first tuning of first image processing algorithm parameters of the measurement image based on the first set of markings; calculating a first measurement value of the first set of markings based on the first tuning; performing a second tuning of second image processing algorithm parameters of the measurement image based on the second set of markings, the second tuning being different from the first tuning; calculating a second measurement value of the second set of markings based on the second tuning; and calculating a marking value based on the first and second measurement values.

[0006] Some embodiments of this disclosure provide a method for performing the operations discussed above.

[0007] Some embodiments of this disclosure provide a charged particle device. The charged particle device may include: a charged particle beam source configured to generate a primary charged particle beam; a charged particle optical system configured to guide the primary charged particle beam to a region on a substrate, the region including a first set of markings and a second set of markings; and a controller including one or more processors and configured to cause the charged particle beam device to perform the operations discussed above.

[0008] Some embodiments of this disclosure provide a method for determining suture markings, the method comprising: obtaining a charged particle image of a first set of markings from a first photolithographic exposure and obtaining a charged particle image of a second set of markings from a second photolithographic exposure, wherein the first markings are located on a first side of a suture boundary and the second markings are located on a second side of the suture boundary. The first set of markings may include a first plurality of structures separated by a first pitch and a second plurality of structures separated by a second pitch; and the second set of markings may include a third plurality of structures separated by a third pitch and a fourth plurality of structures separated by a fourth pitch. The method may further include: determining a first relative position between a first plurality of structures and a second plurality of structures in a first set of markings; calculating a first setting-obtained graph of design offset values ​​and measured offset values ​​between the first plurality of structures and the second plurality of structures; optimizing a first image processing algorithm until the first setting-obtained graph meets a first specified criterion; applying the optimized first image processing algorithm to the first set of markings in a charged particle image; determining a second relative position between a third plurality of structures and a fourth plurality of structures in a second set of markings; calculating a second setting-obtained graph of design offset values ​​and measured offset values ​​between the third plurality of structures and the fourth plurality of structures; optimizing a second image processing algorithm until the second setting-obtained graph meets a second specified criterion; applying the optimized second image processing algorithm to the second set of markings in a charged particle image; calculating a third setting-obtained graph of design offset values ​​and measured offset values ​​between the first set of markings and the second set of markings; and determining suture marking values ​​based on the intercept of the third setting-obtained graph.

[0009] Other advantages of the embodiments of this disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which certain embodiments of the invention are illustrated and exemplified. Attached Figure Description

[0010] The above and other aspects of this disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings.

[0011] Figures 1A to 1B This is a schematic representation of an example lithography system consistent with embodiments of this disclosure.

[0012] Figures 2A to 2BThis is a schematic representation of an example charged particle beam inspection system consistent with embodiments of this disclosure.

[0013] Figures 3A to 3B This is a schematic representation of an example of a wafer exposure field consistent with embodiments of this disclosure.

[0014] Figure 4 This is a schematic representation of an example overlay configuration based on a comparative embodiment.

[0015] Figures 5A to 5C This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0016] Figure 6 This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0017] Figure 7 This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0018] Figures 8A to 8B This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0019] Figures 9A to 9C This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0020] Figure 10 This is a schematic representation of an example overlay configuration consistent with embodiments of this disclosure.

[0021] Figure 11 This is a process flow diagram illustrating an exemplary overlay method consistent with embodiments of this disclosure. Detailed Implementation

[0022] 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, wherein, unless otherwise indicated, the same numerals in the different drawings denote the same or similar elements. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations. Rather, they are merely examples of apparatuses and methods consistent with various aspects of the disclosed embodiments as set forth in the appended claims. For example, although some embodiments are described in the context of the use of electron beams, this disclosure is not limited thereto. Other types of charged particle beams can be applied similarly. Furthermore, other imaging systems can be used, such as optical imaging, photoelectric detection, X-ray detection, etc.

[0023] Manufacturing integrated circuits (ICs) with extremely small structures or components is a complex, time-consuming, and expensive process, typically involving hundreds of individual steps. Even an error in one step can lead to a defect in the completed IC, rendering it unusable. Therefore, one goal of the manufacturing process is to avoid such defects in order to maximize the number of functional ICs manufactured in the process; that is, to increase the overall yield of the process.

[0024] For example, lithography apparatuses can be used to manufacture ICs. In this case, a mask or stencil can contain or provide a circuit pattern (“design layout”) corresponding to a single layer of the IC, and this circuit pattern can be transferred to the target portion (e.g., comprising one or more dies) on a substrate (e.g., a silicon wafer) by methods such as irradiating the target portion through the circuit pattern on the mask, which has been coated with a radiation-sensitive material (“resist”). As feature sizes continue to shrink, overlay, alignment, and other metrological measurements become increasingly important. Furthermore, some modern lithography systems can print on small exposure areas on the wafer, making it impossible to print an entire layer of an IC chip or other device in a single scan exposure. Therefore, multiple circuit patterns must be printed with their edges connected in contact or overlapping, so that the entire device layer can be “stitched” together. This places more challenging requirements on overlay within the system, and the space for overlay marks on modern wafers is shrinking. For example, high-NA EUV lithography systems may require multiple stitched exposure fields to produce the device layer, which may require compact overlay marks capable of producing accurate overlay measurements.

[0025] Embodiments of this disclosure provide systems and methods for suture alignment, overprinting, and other measurements using compact markers with a small footprint. In some embodiments, the suture overprinting markers can be made small enough that two corresponding markers on either side of the suture boundary can be fitted into a single image capture of the inspection device. The overprinting markers can be designed such that their precise position can be fine-tuned by further analysis of the captured image. By pre-tuning each overprinting marker before comparison, the placement and overprinting of the suture area can be monitored and controlled using compact markers within a scribe line in an area within the device or the suture area.

[0026] For clarity, the relative dimensions of components in the accompanying drawings may be exaggerated. Throughout the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only differences relative to the various embodiments are described. As used herein, unless otherwise specifically stated, the term "or" covers all possible combinations except those that are impractical. For example, if an illustrative component may include A or B, then unless otherwise specifically stated or impractical, the component may include A or B or A and B. As a second example, if an illustrative component may include A, B, or C, then unless otherwise specifically stated or impractical, the component may include A or B or C, or A and B, or A and C, or B and C, or A and B and C.

[0027] Figure 1A This is a schematic block diagram of various subsystems of a lithography system consistent with embodiments of this disclosure. For example... Figure 1A As shown, the photolithography system 10 may include an irradiation source 12, irradiation optics 14, a mask 16 (or a mask plate), and transmission optics 18. The irradiation source 12 may be a deep ultraviolet excimer laser source or other types of sources, including extreme ultraviolet (EUV) sources. The irradiation optics 14 may define partial coherence and may include optics 14a and 14b that shape the radiation from the irradiation source 12. The transmission optics 18 may project an image of the mask pattern onto a substrate plane 19. An adjustable filter or aperture at the pupil plane of the projection optics 18 may limit the range of beam angles impacting the substrate plane 19.

[0028] In a photolithography apparatus, an irradiation source 12 provides an irradiation (i.e., radiation) beam 13 to a mask 16, which can pattern the irradiation beam 13. For example, the mask 16 can include any patterning device, such as a photomask, a programmable mirror array (such as a digital micromirror device (DMD)), a computer-generated hologram (CGH), or other elements configured to selectively modulate or block portions of the irradiation beam 13 to pattern it. The pattern can include, for example, a layer in an integrated circuit or another semiconductor device pattern. A projection optics 18 can guide and shape the irradiation onto the substrate W via the mask 16. An adjustable filter or aperture 17 at the pupil plane of the projection optics can limit the range of beam angles impacting the substrate plane 19, where the maximum possible angle defines the numerical aperture NA of the projection optics as NA = sin(Θ). max ).

[0029] The term "projection optics" is broadly defined herein as any optical component that can alter the wavefront of the radiation beam. For example, projection optics may include at least some of illumination optics 14 and transmission optics 18. In some embodiments, projection optics 18 may project a scaled-down image of the illuminated pattern at a scaling ratio of, for example, 4:1 or 5:1. As discussed below, in some embodiments, projection optics may include a deformation system in which a first scaling ratio in a first direction on the pattern image may differ from a second scaling ratio in a second vertical direction on the pattern image.

[0030] For example, Figure 1B This is a schematic block diagram of various subsystems of the EUV lithography system 11 consistent with embodiments of this disclosure. The EUV lithography system 11 can correspond to... Figure 1A The lithography system 10. For example... Figure 1B As shown, the EUV lithography system 11 may include: an illumination system comprising a source collector module 112 and an illumination optics 114; a reflective mask or other patterning apparatus 116; and a projection optics 118. In the source collector module 112, EUV radiation may be generated by plasma. The EUV radiation may then be shaped by the illumination optics 114, patterned by the mask 116, and reflected toward the projection optics 118. The projection optics 118 may project a reduced image of the pattern from the mask 116 onto the wafer W. For example, the mask 116 and the wafer W may be scanned along the scanning direction illustrated by the double arrows.

[0031] EUV mirrors, masks, and other optical elements can operate within narrow angular ranges, such as at grazing or near-normal incidence. For example, in some embodiments, the incoming light 113a can be incident on the mask 116 within an incident angle range of, for example, 3 to 7 degrees. This can impose difficult constraints on the spatial relationships of mirrors and other elements within the illumination and projection system. For example, it may be difficult to arrange mirrors facing each other so that they do not block the beam as it passes through the side of the preceding mirror in a reflection sequence. Furthermore, it may be desirable to avoid overlap between the incoming light 113a toward the mask 116 and the outgoing light 113b reflected from the mask 116. This problem can occur, for example, when the NA is too large for a given principal ray angle.

[0032] To overcome these problems, in some embodiments... Figure 1A The projection optical element 18 and Figure 1B The NA or scaling factor of 118 in the mask may be anisotropic. For example, the spatial extent of the incoming light 113a and the outgoing light 113b may be compressed in a direction corresponding to the scanning direction. The representation of the pattern design layout on the mask 116 may be spatially distorted in a complementary manner, as shown below relative to Figure 3AFurther discussion follows. By using anamorphic projection optics with a first reduction ratio in the scanning direction and a second reduction ratio in the perpendicular non-scanning direction, the original distortion-free pattern design can be reproduced on the wafer W. For example, some high-NA EUV systems can use anamorphic optics with an 8x4 reduction ratio. Thus, in some embodiments, the reduction ratio in the scanning direction may be 8:1, and in the non-scanning direction it may be 4:1. Inspection systems such as charged particle beam inspection systems can be used to perform measurement and defect inspection of this pattern. For example, the inspection system can be used to determine the alignment between adjacent or overlay exposure fields.

[0033] Figure 2A An example electron beam inspection (EBI) system 100 consistent with embodiments of this disclosure is illustrated. The EBI system 100 can be used for imaging. Figure 2A As shown, the EBI system 100 includes a main chamber 101, a loading / locking chamber 102, a beam tool 104, and an Equipment Front End Module (EFEM) 106. The beam tool 104 is located within the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include multiple additional loading ports. The first loading port 106a and the second loading port 106b receive wafer front-opening transfer cassettes (FOUPs) containing wafers to be inspected (e.g., one or more semiconductor wafers made of (multiple) other materials) or samples (wafers and samples can be used interchangeably). A "batch" is a plurality of wafers that can be processed as a single load.

[0034] One or more robotic arms (not shown) in EFEM 106 can transport the wafer to loading / locking chamber 102. Loading / locking chamber 102 is connected to a loading / locking vacuum pump system (not shown), which removes gas molecules from loading / locking chamber 102 to achieve a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) can transport the wafer from loading / locking chamber 102 to main chamber 101. Main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from main chamber 101 to achieve a second pressure below the first pressure. After reaching the second pressure, the wafer is inspected by a beam tool 104. Beam tool 104 can be a single-beam system or a multi-beam system.

[0035] The controller 109 is electronically connected to the beam tool 104. The controller 109 may be a computer configured to perform various controls of the EBI system 100. Although in Figure 2A The controller 109 is shown outside the structure including the main chamber 101, the loading / locking chamber 102 and the EFEM 106, but it should be understood that the controller 109 may be part of the structure.

[0036] In some embodiments, controller 109 may include one or more processors (not shown). A processor may be a general-purpose or specific electronic device capable of manipulating or processing information. For example, a processor may include any number of central processing units (or “CPU”), graphics processing units (or “GPU”), optical processors, programmable logic controllers, microcontrollers, microprocessors, digital signal processors, intellectual property (IP) cores, programmable logic arrays (PLAs), programmable array logic (PALs), general-purpose array logic (GALs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), system-on-a-chip (SoCs), application-specific integrated circuits (ASICs), and any combination of any type of circuitry capable of data processing. A processor may also be a virtual processor, comprising one or more processors distributed across multiple machines or devices coupled via a network.

[0037] In some embodiments, controller 109 may also include one or more memories (not shown). The memories can be general-purpose or specific electronic devices capable of storing processor-accessible (e.g., via a bus) code and data. For example, the memories can include any number of random access memory (RAM), read-only memory (ROM), optical discs, magnetic disks, hard disks, solid-state drives, flash drives, secure digital cards (SD cards), memory sticks, compact flash (CF) cards, or any combination of any type of storage device. The code and data can include an operating system (OS) and one or more applications (or “applications”) for a specific task. The memories can also be virtual memory, which includes one or more memories distributed across multiple machines or devices coupled via a network.

[0038] Figure 2B The illustration shows an example multi-beam tool 104 (also referred to herein as apparatus 104) and an image processing system 290 consistent with embodiments of the present disclosure, which can be configured for use in EBI system 100 ( Figure 2A ).

[0039] The beam tool 104 includes a charged particle source 202, a gun aperture 204, a converging lens 206, a primary charged particle beam 210 emitted from the charged particle source 202, a source conversion unit 212, multiple beams 214, 216, and 218 of the primary charged particle beam 210, a primary projection optics system 220, a motorized wafer stage 280, a wafer holder 282, multiple secondary charged particle beams 236, 238, and 240, a secondary optics system 242, and a charged particle detection device 244. The primary projection optics system 220 may include a beam splitter 222, a deflection scanning unit 226, and an objective lens 228. The charged particle detection device 244 may include detection sub-regions 246, 248, and 250.

[0040] The charged particle source 202, the gun aperture 204, the converging lens 206, the source conversion unit 212, the beam splitter 222, the deflection scanning unit 226, and the objective lens 228 can be aligned with the primary optical axis 260 of the device 104. The secondary optical system 242 and the charged particle detection device 244 can be aligned with the secondary optical axis 252 of the device 104.

[0041] Charged particle source 202 can emit one or more charged particles, such as electrons, protons, ions, muons, or any other charged particles. In some embodiments, charged particle source 202 can be an electron source. For example, charged particle source 202 can include a cathode, extractor, or anode, wherein primary electrons can be emitted from the cathode and extracted or accelerated to form a primary charged particle beam 210 (in this case, a primary electron beam) with a cross (virtual or real) 208. For ease of explanation and without ambiguity, electrons are used as examples in some descriptions herein. However, it should be noted that any charged particle can be used in any embodiment of this disclosure, not limited to electrons. The primary charged particle beam 210 can be visualized as being emitted from the cross 208. The aperture 204 can block peripheral charged particles of the primary charged particle beam 210 to reduce the Coulomb effect. The Coulomb effect can lead to an increase in the probe spot size.

[0042] Source conversion unit 212 may include an image forming element array and a beam-limiting aperture array. The image forming element array may include an array of micro-deflectors or microlenses. The image forming element array can form multiple parallel images (virtual or real) at the intersection 208 of multiple beam waves 214, 216, and 218 of the primary charged particle beam 210. The beam-limiting aperture array can limit the multiple beam waves 214, 216, and 218. Although in Figure 2B Three beams 214, 216, and 218 are shown, but embodiments of this disclosure are not limited thereto. For example, in some embodiments, device 104 may be configured to generate a first number of beams. In some embodiments, the first number of beams may be in the range of 1 to 1000. In some embodiments, the first number of beams may be in the range of 200 to 500. In an exemplary embodiment, device 104 may generate 400 beams.

[0043] The converging lens 206 can focus the primary charged particle beam 210. The currents of the beams 214, 216, and 218 downstream of the source conversion unit 212 can be changed by adjusting the focusing capability of the converging lens 206 or by changing the radial dimensions of the corresponding beam-limiting apertures within the beam-limiting aperture array. The objective lens 228 can focus the beams 214, 216, and 218 onto the wafer 230 for imaging, and can form multiple probe spots 270, 272, and 274 on the surface of the wafer 230.

[0044] Beam splitter 222 can be a Wien filter type beam splitter that generates electrostatic dipole fields and magnetic dipole fields. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on the charged particles (e.g., electrons) of beam waves 214, 216, and 218 on the charged particles can be substantially equal in amplitude and opposite in direction to the force exerted by the magnetic dipole field on the charged particles. Therefore, beam waves 214, 216, and 218 can pass directly through beam splitter 222 with zero deflection angle. However, the total dispersion of beam waves 214, 216, and 218 generated by beam splitter 222 can also be non-zero. Beam splitter 222 can separate secondary charged particle beams 236, 238, and 240 from beam waves 214, 216, and 218 and guide secondary charged particle beams 236, 238, and 240 toward secondary optical system 242.

[0045] The deflection scanning unit 226 can deflect beams 214, 216, and 218 to scan probe spots 270, 272, and 274 on the surface region of wafer 230. In response to the incident beams 214, 216, and 218 at probe spots 270, 272, and 274, secondary charged particle beams 236, 238, and 240 can be emitted from wafer 230. The secondary charged particle beams 236, 238, and 240 can include charged particles (electrons) with an energy distribution. For example, the secondary charged particle beams 236, 238, and 240 can be a secondary electron beam comprising secondary electrons (energy ≤ 50 eV) and backscattered electrons (energy between 50 eV and the landing energy of beams 214, 216, and 218). The secondary optical system 242 can focus the secondary charged particle beams 236, 238, and 240 onto the detection sub-regions 246, 248, and 250 of the charged particle detection device 244. The detection sub-regions 246, 248, and 250 can be configured to detect the corresponding secondary charged particle beams 236, 238, and 240, and generate corresponding signals (e.g., voltage, current, etc.) for reconstructing an image of the structure on or below the surface region of the wafer 230.

[0046] The generated signals can represent the intensity of the secondary charged particle beams 236, 238, and 240, and can be provided to an image processing system 290 that communicates with the charged particle detection device 244, the primary projection optics system 220, and the motorized wafer stage 280. The movement speed of the motorized wafer stage 280 can be synchronized and coordinated with the beam deflection controlled by the deflection scanning unit 226, so that the movement of the scanning probe spots (e.g., scanning probe spots 270, 272, and 274) can orderly cover the region of interest on the wafer 230. The parameters of this synchronization and coordination can be adjusted to accommodate different materials of the wafer 230. For example, different materials of the wafer 230 may have different resistivity-capacitance characteristics, which may result in different signal sensitivities to the movement of the scanning probe spots.

[0047] The intensities of the secondary charged particle beams 236, 238, and 240 can vary depending on the external or internal structure of the wafer 230, thus indicating whether the wafer 230 contains defects or other errors. Furthermore, as discussed above, beams 214, 216, and 218 can be projected onto different locations on the top surface of the wafer 230 or different sides of a local structure of the wafer 230 to generate secondary charged particle beams 236, 238, and 240 with varying intensities. Therefore, by mapping the intensities of the secondary charged particle beams 236, 238, and 240 to regions of the wafer 230, the image processing system 290 can reconstruct an image reflecting the characteristics of the internal or external structure of the wafer 230.

[0048] In some embodiments, the image processing system 290 may include an image acquirer 292, a storage device 294, and a controller 296. The image acquirer 292 may include one or more processors. For example, the image acquirer 292 may include a computer, server, mainframe, terminal, personal computer, any kind of mobile computing device, or a combination thereof. The image acquirer 292 may be communicatively coupled to the charged particle detection device 244 of the beam tool 104 via a medium such as an electrical conductor, fiber optic cable, portable storage medium, IR, Bluetooth, Internet, wireless network, radio, or a combination thereof. In some embodiments, the image acquirer 292 may receive signals from the charged particle detection device 244 and may construct an image. The image acquirer 292 may thus acquire scanning charged particle microscopy (SCPM) images of the wafer 230. The image acquirer 292 may also perform various post-processing functions, such as generating contours, overlaying indicators on the acquired images, etc. The image acquirer 292 may be configured to perform adjustments to the brightness and contrast of the acquired images. In some embodiments, storage device 294 may be a storage medium such as a hard disk, flash drive, cloud storage device, random access memory (RAM), or other types of computer-readable storage. Storage device 294 may be coupled to image acquirer 292 and may be used to store scanned original image data as the original image and post-processed images. Image acquirer 292 and storage device 294 may be connected to controller 296. In some embodiments, image acquirer 292, storage device 294, and controller 296 may be integrated into a single control unit.

[0049] In some embodiments, image acquisition unit 292 may acquire one or more SCPM images of a wafer based on imaging signals received from charged particle detection device 244. The imaging signals may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image comprising multiple imaging regions. The single image may be stored in storage device 294. The single image may be an initial image that can be divided into multiple regions. Each region may include an imaging region containing features of wafer 230. The acquired images may include multiple images of a single imaging region of wafer 230 sampled multiple times over a time series. Multiple images may be stored in storage device 294. In some embodiments, image processing system 290 may be configured to perform image processing steps on multiple images of the same location on wafer 230.

[0050] In some embodiments, the image processing system 290 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain the distribution of detected secondary charged particles (e.g., secondary electrons). Charged particle distribution data collected during the detection time window can be combined with corresponding scan path data of beams 214, 216, and 218 incident on the wafer surface to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the internal or external structure of the wafer 230, and thus can be used to reveal any defects or other errors that may exist in the wafer.

[0051] In some embodiments, the charged particles can be electrons. When electrons from the primary charged particle beam 210 are projected onto the surface of the wafer 230 (e.g., probe spots 270, 272, and 274), the electrons from the primary charged particle beam 210 can penetrate the surface of the wafer 230 to a certain depth and interact with the particles of the wafer 230. Some electrons from the primary charged particle beam 210 can elastically interact with the material of the wafer 230 (e.g., in the form of elastic scattering or collision) and can be reflected or bounced off the surface of the wafer 230. Elastic interaction conserves the total kinetic energy of the interacting subjects (e.g., electrons from the primary charged particle beam 210), where the kinetic energy of the interacting subjects is not converted into other forms of energy (e.g., heat, electromagnetic energy, etc.). Such reflected electrons generated by elastic interaction can be called backscattered electrons (BSE). Some electrons from the primary charged particle beam 210 can inelastically interact with the material of the wafer 230 (e.g., in the form of inelastic scattering or collision). Inelastic interaction does not conserve the total kinetic energy of the interacting subjects, where some or all of the kinetic energy of the interacting subjects is converted into other forms of energy. For example, through inelastic interactions, the kinetic energy of some electrons in the primary charged particle beam 210 may lead to electronic excitation and transitions between material atoms. This inelastic interaction can also generate electrons that leave the surface of the wafer 230; these electrons can be referred to as secondary electrons (SEs). The yield or emission rate of BSEs and SEs depends, for example, on the material being examined and the landing energy of the electrons from the primary charged particle beam 210 on the material surface. The energy of the electrons in the primary charged particle beam 210 can be partly determined by its accelerating voltage (e.g., ...). Figure 2B The accelerating voltage between the anode and cathode of the charged particle source 202 is imparted. The amounts of BSE and SE can be more or less (or even the same) than the injected electrons of the primary charged particle beam 210.

[0052] SEM can scan overlay or other measurement marks on the wafer surface. For example, in-die marks may be located in unused areas of a patterned region, or functional features may be used for measurement purposes. Alternatively or additionally, overlay or other test marks may be located in scribe lines or other non-patterned areas around the perimeter of the exposure field. These marks can be used to measure, for example, misalignment or other spatial parameters between adjacent fields in the same device layer or overlapping fields in two different device layers. Furthermore, some circuit layers may be too large to be formed on a single standard-sized exposure die, such as 26 × 33 mm. Similarly, some lithography systems may not be able to print patterns of this size in a single exposure. In such cases, it may be necessary to “stitch” multiple exposures together side-by-side to form a single continuous device layer. Stitching exposure processes may impose stringent placement requirements to ensure the production of a fully functional device, and stitch overlay marks can be used on either side of the stitch boundary.

[0053] Figure 3A An example of an exposed wafer W consistent with embodiments of this disclosure is illustrated, each wafer having multiple fields 31. As... Figure 3A As shown, the wafer W can contain multiple fields 31, each field corresponding to a mask (e.g., Figure 1A Mask 16 or Figure 1B A region of (116). In some embodiments, mask 316 can be used to generate the same circuit pattern "C" in each of the plurality of fields 31, for example by using a photolithography system (e.g., Figure 1A lithography system 10 or Figure 1B (11). In some embodiments, each field 31 may include one or more dies.

[0054] In some embodiments, the illumination system can scan the exposure slit 313 on the mask 316 along a scanning direction (indicated by arrows) to progressively transfer different portions of the mask pattern onto the field 31. For example, in some embodiments, the field size can be 26 × 33 mm. The exposure slit 313 can span the width of the mask 316 and has a thickness of, for example, 1 to 2 mm, and can be scanned along the length of the mask area to transfer the pattern onto the field 31.

[0055] As discussed above, in addition to the patterned region “C” within the dashed box of mask 316, the exposure process can also transfer an additional alignment pattern 370 onto the wafer. For example, the alignment pattern 370 can be configured to determine the alignment, overlay, distortion, or other spatial parameters of pattern “C” relative to itself, adjacent patterns in the same layer, or overlapping patterns in previously or subsequently formed layers. Generally, in this disclosure, such patterns may be referred to as overlay patterns, and their corresponding printed features on the substrate may be referred to as overlay marks. In particular, embodiments of this disclosure can be described relative to stitch overlay, for example in high-NA EUV applications. However, it should be understood that in some embodiments of this disclosure, the systems and methods disclosed herein can be applied to other metrology processes. The overlay pattern 370 may be located around the periphery of the patterned region “A”, for example, in scribe lines or other non-patterned areas. In some embodiments, the overlay pattern 370 may be located within a device patterned area.

[0056] like Figure 3A As shown at the bottom, field 31 can be exposed using two masks. For example, a first mask 316a can be used to generate a first pattern "A" in the first subfield 31a during a first exposure, and a second mask 316b can be used to generate a second pattern "B" in the second subfield 31b during a second exposure. Patterns "A" and "B" can be stitched together along stitch boundary 381 to form a single continuous device layer. Stitch overlay patterns 370a / b can be arranged in masks 316a / b along mask stitch boundary 371 to enable overlay measurements. Each pair of stitch overlay marks from adjacent subfields can be measured relative to each other to determine overlay errors, such as translational or rotational offsets, distortion, etc.

[0057] In some embodiments, the design layout of patterns “A” and “B” may be distorted from the actual desired pattern to account for, for example, the anisotropic reduction ratio of the projection optics. When the reduction ratio is anisotropic, for example, 8 in the scanning direction and 4 in the direction perpendicular to the scanning direction, the representation on mask 316a / b can be spatially scaled by a factor of 8 in the scanning direction 4 in the non-scanning direction relative to the printed pattern on field 31. When, for example, an image of the pattern on mask 316a is projected onto subfield 31a, the projection optics can spatially scale the image by a factor of ⅛ in the scanning direction and by a factor of ¼ in the non-scanning direction. Thus, a 26 × 33 mm exposure area can be patterned using two subfields, each subfield being 26 × 16.5 mm. Due to the anisotropy of the reduction ratio, the shape and size of the features of mask 316a / b may differ from the corresponding features in the design layout. This distortion can make measurement operations such as stitching overlay particularly difficult, especially when aligning fine pattern feature types typically printed on high NA EUV systems.

[0058] While the foregoing examples illustrate a stitching embodiment of two subfields with different patterns being sewn together, embodiments of this disclosure are not limited thereto. For example, field 31 may comprise three, four, or more subfields arranged linearly or in a 2D array. Field 31 may include a single repeating device pattern at each subfield, or may use more than two unique device patterns. Furthermore, it should be understood that exposure field 31 is not limited to the size or shape of the examples given above, such as 26 × 33 mm.

[0059] Figure 3B The diagram schematically illustrates the effects of good and bad stitching on the same device layer and subsequent device layers. At the top of the figure, the first and second subfields 31a / b are aligned in the exposure field of the first device layer to form a properly stitched pattern. For example, the first device layer may correspond to... Figure 3A The bottom layer is shown. Subfields 31a / b can be printed from mask 316a / b using, for example, a high-NA EUV lithography system with anisotropic projection optics. The stitching pattern in the first device layer can be overlaid and aligned with region 31c in the second device layer. For example, the second layer can correspond to Figure 3A The layer shown at the top.

[0060] With proper stitching, subfields 31a / b are not only correctly aligned with each other, but they are also correctly aligned with field 31c. Poor stitching can lead to misalignment between subfields 31a and 31b, potentially causing further alignment errors in field 31c. These alignment errors can be more difficult to compensate for than those from a single field exposure. Therefore, precise measurement of the stitching alignment between subfields is necessary.

[0061] Conventional markings include optical overlay markings and SEM overlay markings. Existing optical overlay markings can include IBO (image-based overlay) markings, yielded star markings, including uDBO (micro-diffraction-based overlay) and cDBO (continuous diffraction-based overlay). SEM overlay markings can include, for example, contact hole patterns, line-space patterns, or device-like patterns. One problem with conventional optical overlay markings is that they consume a significant amount of space on the wafer. Current SEM overlay markings do not have built-in set-overlay values ​​in the 0.5 to 2 micrometer region.

[0062] Figure 4A suture overprinting system according to a comparative embodiment is schematically illustrated. By means of a comparative method, the suture overprinting marks may consume a large area on either side of the suture boundary. For example, a first subfield 41a corresponding to a first mask pattern may include a first suture overprinting mark 480a, and a second subfield 41b corresponding to a second mask pattern may include a second suture overprinting mark 480b. Suture overprinting marks 480a and 480b may each include a row of periodic structures 483 having an x-direction pitch Px. The structure in the first suture overprinting mark 480a on the first side of the suture boundary 481 may have a programmed offset dx with the structure in the second suture overprinting mark 480b on the second side of the suture boundary. The default programmed offset dx can be zero. An inspection device can acquire and analyze images of the overprinting marks to determine, for example, the average offset between two marks. To acquire sufficient data points for reliable measurements, a large number of periodic structures 483 may be required; however, due to the lack of known references, it is difficult to directly assess whether each data point from a corresponding pair of periodic structures will give the correct dx value.

[0063] Embodiments of this disclosure provide systems and methods for performing suture overlay and other metrological measurements using compact markers with a small footprint and known references. In some embodiments, the suture overlay markers can be made small enough that two corresponding markers on either side of the suture boundary can fit within a single high-resolution field of view of an inspection apparatus, such as a SEM inspection tool. By making the suture overlay markers small enough to fit within a single SEM field of view, it enables in-device region overlay metrology. In some embodiments, the total width of the overlay markers can be, for example, between 0.2 and 5 micrometers, or more specifically between 0.5 and 2 micrometers. Accurate results can be achieved within this small measurement footprint by performing a pre-tuning process before aligning the two markers with each other. For example, each overlay marker can be configured such that its image processing algorithm parameters can be individually tuned before determining the overlay or another measurement parameter.

[0064] Figures 5A to 5C An example stitching process consistent with embodiments of this disclosure is illustrated. Figure 5A Measurement images 582 of the first overlay mark 580a and the second overlay mark 580b are shown for the ideal case with no overlay error (top) and for the case with a non-zero overlay error value OPO on the product (bottom). Image 582 can be, for example, a charged particle beam image, such as an SEM image. For example, it can be used... Figure 2A EBI system 100 or Figure 2BAn electron beam tool 104 is used to acquire images. In some embodiments, image 582 may be an optical or other measurement image. In some embodiments, image 582 may be generated from a single field of view of an SEM or other inspection apparatus. For example, the field of view may have an x-dimensional dimension, for example, between 0.5 micrometers and 2 micrometers.

[0065] A first set of markings 580a can be printed on a portion of a first subfield 51a on the wafer, and a second marking 580b can be printed on a portion of a second subfield 51b on the wafer. In some embodiments, the wafer can correspond to, for example... Figures 3A to 3B For the wafer W, a first subfield may correspond to subfield 31a printed through mask 316a, and a second subfield may correspond to subfield 31b printed through mask 316b. Overlay marks 580a and 580b may be arranged on opposite sides of the stitch boundary 581. It should be understood that within other portions (not shown) of subfields 51a / b, functional device features may contact or cross the stitch boundary 581 to meet or overlap each other and form a continuous device layer.

[0066] The first set of markings 580a and the second set of markings 580b may each include one or more unit cells having at least two sets of structures. For example, the first set of markings 580a includes a plurality of first structures (solid circles) arranged at a first pitch Px1 and a plurality of second structures (hollow circles) arranged at a second pitch Px2. Similarly, the second set of markings 580b includes a plurality of third structures (solid circles) arranged at a first pitch Px1 and a plurality of fourth structures (hollow circles) arranged at a second pitch Px2. The discussion of the unit cells within each marking is given below with respect to the first set of markings 580a, but it applies similarly to the second set of markings 580b. Furthermore, although the markings are disclosed with respect to a single direction x, these structures may also have similar programmed offsets in another direction y to enable two-dimensional measurement.

[0067] Each structure within the first plurality of structures can be aligned with a corresponding structure in the second plurality of structures having a built-in offset. The first plurality of structures and the second plurality of structures can be arranged according to a designed (“set”) overlay value such that each successive pair is offset by an increment of the pitch difference dP, where dP = Px2 - Px1. For example, as... Figure 5A As shown, a unit cell may include five pairs of first and second structures, wherein these pairs are designed to have set-overlap values ​​of -2dP, -dP, 0, dP, and 2dP, respectively. Further, the first overlap mark 580a of the first field can be designed to be perfectly aligned with the second overlap mark 580b. Therefore, multiple second structures and multiple third structures can be designed to have the same overlap values ​​of -2dP, -dP, 0, dP, and 2dP, respectively.

[0068] However, as in Figure 5A As seen at the bottom, subfields 51a and 51b will actually print some non-zero overprint error (OPO) on the product, which must be measured and interpreted. Furthermore, individual structures within each overprint mark, or their images, may not be perfectly aligned with their set values. For example, while pitch control of multiple structures in a photolithography process may be very accurate, CD control may be less accurate and may struggle to produce a clear image of the structure. Therefore, to accurately measure OPO or other measurements using compact overprint marks, embodiments of this disclosure can independently tune the image processing algorithm parameters of the first and second overprint marks in each exposure area before comparing the marks to each other.

[0069] Figure 5B An example process for tuning image processing algorithm parameters, consistent with embodiments of this disclosure, is illustrated. This process may include comparing a set of design offset values ​​between a first plurality of structures and a second plurality of structures with a set of measured offset values ​​between the first plurality of structures and the second plurality of structures. Graphs (1) to (2) may correspond to, for example, […]. Figure 5A The measurement values ​​of the measurement images of the overlay marks 580a and 580b. The first curve (1) can correspond to the measurement values ​​from the first mask (such as, for example) Figure 3A The first curve (1) shows the initial measurement values ​​of the first overlay mark 580a in the first subfield printed by the first mask 316a. The setting values ​​along the x-axis can be obtained by design. For example, the x-axis of the first curve (1) can show the setting-overlay values ​​between the first and second structures, such as -2dP, -dP, 0, dP, 2dP, 3dP, etc., according to the design offset of the overlay mark. The y-axis of the first curve (1) can show the initial measurement (or "obtained") overlay value corresponding to each setting value. The initial obtained values ​​can be obtained by analyzing the measurement image to determine the measurement offset at each pair of first and second structures. Next, the image processing algorithm parameters of the measurement image can be iteratively tuned until the obtained overlay value closely matches the given setting value. For example, the image processing algorithm parameters can be adjusted until the curve fit between the setting value and the obtained value meets a predetermined criterion. For example, the curve fit can be a linear fit. The criterion can include a slope of essentially 1 or a y-intercept of essentially 0. For example, in some embodiments, image processing algorithm parameters can be tuned until the slope approaches 1 to within a first predetermined threshold, or the y-intercept approaches 0 to within a second predetermined threshold. In some embodiments, the criterion may include, for example, a weighted combination of slope and intercept thresholds. The result is a series of refined or tuned values ​​of the first overlay marking 580a, which can be used for stitching or other measurement processes. The refined or tuned values ​​may correspond to, for example, the center value in the x-direction of each individual structure.

[0070] The same process can be performed on the second set of markings 580b for the second setup-obtaining curve (2) in a similar manner. However, although the first set of markings and the second set of markings 580a / b can be captured in the same measurement image, the specific image tuning of the second set of markings 580b in the second curve (2) can be independent of the tuning in the first curve (1). Tuning parameters can include parameters used in any image processing algorithm. Image processing algorithms can be, for example, template matching, edge or contour finding, shape fitting, region segmentation, etc. Parameters can be any shape parameter (such as radius or line width), any edge search parameter (such as threshold, derivative parameter, etc.), any image enhancement parameter (such as image filter kernel parameter), grayscale tuning, or any other suitable image tuning parameter.

[0071] After tuning the values ​​obtained from the first and second sets of markings, these values ​​can be compared with each other to determine the desired measurement parameters. For example, Figure 5C An example process for identifying measurement parameters from tuning values ​​(such as OPO) consistent with embodiments of this disclosure is illustrated. Graph (3) illustrates the setup-obtaining graph of the offset between overlay marks 580a and 580b, which can be used to determine the overlay value OPO on a product. The offset can represent, for example, a global offset between the entire mark 580a and the entire mark 580b, or it can include offsets measured between structural subsets within each overlay mark. For example, as... Figure 5C As shown on the right, graph (3) can represent the setup-obtained graph of the differences between the multiple second structures of marker 580a and the multiple third structures of marker 580b. In this case, the x-axis will again show the same setup value for each crossover pair, as discussed above, in increments of dP. However, the value along the y-axis can correspond to the design offset dP at each pair of structures plus the overlay value on the product. By linearly fitting the points on graph (3), the y-intercept can be used as the average of the OPO values ​​from each pair of structures. Thus, the y-intercept can be accepted as the OPO value between markers 580a and 580b. The OPO value can be combined with other measurements from further stitching overlay markers to determine, for example, overlay parameters between the first and second subfields. For example, the measurements can be used to control process parameters in a semiconductor manufacturing system, such as Figures 1A to 1B The photolithography apparatus 10 or 11.

[0072] In some embodiments, a more complex structural arrangement can be provided in the overlay marks to generate additional information. For example, additional sets of structures can be arranged with additional pitches in the x and y directions. Furthermore, multiple rows of structures with the same pitch can be arranged at different distances from the stitch boundary or other edges of the exposure field.

[0073] Figure 6 A further set of examples of overlay marks 680a to 680d consistent with embodiments of the present disclosure is illustrated. In some embodiments, mark pairs 680a / b or 680c / d can be captured within a single field of view 682 of the inspection apparatus. Overlay marks 680a and 680b depict an array of two-pitch staggered structures. For example, overlay mark 680a may include a first plurality of structures arranged in a first 2D array having a first x-pitch Px1 and a first y-pitch Py1. A second plurality of structures may be staggered in a second 2D array with a second x-pitch Px2 and a second y-pitch Py2. Similarly, the second overlay mark 680b may include corresponding third and fourth plurality of structures staggered in a third and fourth array. The third and fourth arrays may be arranged in a manner consistent with the above. Figure 5A The arrangement discussed is similar to that at the first x-pitch and second x-pitch, as well as the first y-pitch and second y-pitch. Multiple setup-acquisition curves can be calculated for each pitch by providing additional marker rows. Multiple setup-acquisition curves can be combined in a weighted combination to calculate the optimal tuning parameters. Similarly, multiple setup-acquisition curves can be calculated when determining overlay errors or other measurement parameters on a product. Additionally, using a 2D array, setup-acquisition curves can be obtained in both the x and y directions.

[0074] In addition to providing multiple setup-acquisition curves for tuning and measurement, additional rows can further monitor proximity effects and local placement errors. For example, the first plurality of structures in overprint marking 680a may include multiple rows placed at continuously increasing distances from the stitch boundary 681. Even if the overprint pattern on the corresponding mask has the same pitch for each of these rows, the printed rows may not. For example, the pitch in the first structure row 683 closest to the stitch boundary 681 (i.e., closest to the edge of its exposure subfield) may differ from the pitch in the first structure row 684 furthest from the stitch boundary due to edge exposure and other proximity effects, as well as spatial frequency filtering and other optical effects of the projection system. Typically, proximity effects may gradually diminish with increasing distance from the stitch boundary 681 or other exposure edges. For example, in some embodiments, adjacent rows of the first structure may have substantially equal pitches at, for example, 1 to 2 micrometers from the stitch boundary 681. Therefore, in some embodiments, setup-acquisition curves of different rows can be used to determine proximity errors, edge placement errors, and other effects.

[0075] Typically, any number of staggered structures can be provided, as long as the entire marking can fit within a single field of view of the inspection device. For example, Figure 6The bottom illustration shows the 3-pitch staggered markings 680c and 680d. The features and advantages of these markings correspond to those described above for the 2-pitch markings 680a and 680b, but considering the additional pitch, they can be used to collect more data.

[0076] Furthermore, the 2D array of the structure does not need to be interleaved. For example, Figure 7 Further examples of overlay marks 780a to 780d consistent with embodiments of this disclosure are illustrated. In some embodiments, mark pairs 780a / b or 780c / d can be captured within a single field of view 782 of the inspection apparatus. Overlay marks 780a and 780b depict arrays of 2-pitch block structures. For example, overlay mark 780a may include a first plurality of structures arranged in a first 2D block array having a first x-pitch Px1 and a first y-pitch Py1. A second plurality of structures may be interleaved in a second 2D block array with a second x-pitch Px2 and a second y-pitch Py2. Similarly, the second overlay mark 780b may include corresponding third and fourth plurality of 2D structure block arrays. As discussed above, the third and fourth arrays may be arranged with a first x-pitch and a second x-pitch, and a first y-pitch and a second y-pitch. Typically, any number of block structures can be provided. For example, the marking 780c / d illustrates a 4-pitch block marking with a first pitch, a second pitch, a third pitch, and a fourth pitch in the x and y directions.

[0077] The setup-acquisition curve can be obtained in a manner similar to the embodiments described above, for example, by subtracting the block distance constant BD. For example, the center column of the first and second block arrays separated by the block distance BD can be used as the zero point on the setup-acquisition curve. Then, the incremental distance dP can be expressed in the form dP = Px2 - Px1 - BD. For example, the setup overlay value between the first pair of structures 785 can be -dP, and the setup overlay value between the second pair of structures 786 can be dP.

[0078] The advantage of providing structure within a separate block array is that the consistency of pattern shape and pattern density is greater in any given area than... Figure 6 The staggered structure is higher. This can reduce the computational burden of resolution enhancement techniques such as optical proximity correction. However, due to the large block distance (BD) in the block array design, the staggered design may be less sensitive to scaling errors caused by aberrations in lithography or SEM tools.

[0079] Furthermore, the block markers do not need to be arranged in a 2D array. Figures 8A to 8B The illustration shows another set of markings 880a to 880f consistent with embodiments of the present disclosure. In some embodiments, marking pairs 880a / b, 880c / d, or 880e / f can be captured within a single field of view 882 of the inspection device. Figure 8AThe overlay marks 880a / b and 880c / d depict a linear array of two-pitch block structures. For example, overlay mark 880a may include a first plurality of lines and spatial structures arranged in a first linear block having a first x-pitch Px1. A second plurality of lines and spatial structures may be arranged in a second linear block having a second x-pitch Px2. Figure 8A As illustrated at the top, by removing the block distance constant BD, the original pitch difference formula dP=Px2-Px1 can be recovered. In this way, simple lines and spatial patterns with unique pitches, such as two, four, or another number, can be used in compact spaces to provide high-quality measurement.

[0080] Alternative locations, such as Figure 8B As shown, a single pitch Px can be used, the difference of which is provided by the step size between adjacent sets of markers. For example, overlay markers 880e and 880f can both be set to equal pitch Px. Overlay marker 880e can include a linear array of single-pitch block structures (e.g., a set of four structures illustrated), where the unit cells of the structures are offset from each other by increasing distances Px+d, Px+2d, etc. For example, in some embodiments, d can have a value on the order of, for example, 1 nm. Although not illustrated in the figures, other structures with corresponding negative offsets Px-d, Px-2d, etc., can be arranged to the left. Thus, marker 880e can be tuned by constructing pairs of adjacent unit cells based on a set-to-obtain curve. For example, in the illustrated embodiment, each unit cell includes four linear structures. Thus, for each set overlay value d, 2d, etc., there may be four obtained values ​​that can be averaged or otherwise applied to the linear fit, as shown in the set-to-obtain curve (4).

[0081] At the same time, the spacing between the structures in the overlay mark 880f can, for example, remain constant. Figure 8B As shown, the stitching between two marks can be measured at different offsets such as d, 3d, 6d, and 10d. Alternatively, the stitching mark 880f may include further programmed offsets (not shown) to allow tuning of the image processing algorithm relative to the stitching mark 880f.

[0082] In some embodiments, the overlay marks on either side of the stitch boundary may include different pitches or different combinations of linear and 2D arrays. For example... Figures 9A to 9CThe illustration shows another set of overlay marks 98a to 98d in a suture overlay process consistent with embodiments of the present disclosure. In some embodiments, mark pairs 980a / b or 980c / d can be captured within a single field of view 982 of the inspection apparatus. Overlay mark 980a depicts a 2-pitch linear mark on a first side of the suture boundary 981. The 2-pitch linear mark may include a first plurality of structures arranged at a first x-pitch Px1 and a second plurality of structures arranged at a second x-pitch Px2. Overlay mark 980b depicts a 2-pitch 2D block mark on a second side of the suture boundary 981. The 2-pitch 2D block mark may include a third plurality of structures arranged at a third x-pitch Px3 and a third y-pitch Py3 and a fourth plurality of structures arranged at a fourth x-pitch Px4 and a fourth y-pitch Py4.

[0083] Therefore, the two overlay marks 980a / b can have different shapes, array sizes, and pitches. However, as Figures 9B to 9C As shown, the process used to determine suture markings and other measurement parameters can be compared with that used for... Figures 5B to 5C The basic principles of the discussion are the same (at least in the x-direction, for example, where both markers can be measured). For example, as in... Figure 9B As seen, a first setup-to-get curve (5) can be determined between the setup overlay and the obtained overlay of the first plurality of structures and the second plurality of structures in marker 980a. Based on this curve, the parameters of the image processing algorithm can be tuned until the accurate value of the structure center point is determined. For example, parameter tuning can be used to establish the center position in the x-direction for each structure within at least one of the first plurality of structures and the second plurality of structures. Next, a second setup-to-get curve (6) can be determined between the setup overlay and the obtained overlay of the third plurality of structures and the fourth plurality of structures in marker 980b. Note that due to different pitch pairs, the incremental value dP given in the first setup-to-get curve (5) may not correspond to the incremental value dP in the second setup-to-get curve (6). The same may be true for the third setup-to-get curve (7) discussed below. Further, since there are multiple rows of structures in the overlay marker 980b, in some embodiments, the second setup-to-get curve (7) may include, for example, a weighted combination of values. In some embodiments, only a subset of the third plurality of structures and the fourth plurality of structures may be selected for tuning. The image processing algorithm parameters can be tuned independently again relative to the 980b marker to determine the center position of each of the third and fourth plurality of structures in the x-direction.

[0084] Finally, as in Figure 9C As can be seen, a third setting—obtaining a curve—can be determined between two overlay marks. This third setting—obtaining a curve—can take various forms. For example, the third setting—obtaining a curve—can be... Figure 9CMeasurements are taken between any pair of linear and 2D arrays shown on the right, or it can include a combination of two other pairs. This third setting—obtaining the y-intercept of the graph—can be used as an overlay or other measurement value on the product. Figure 9A The same principle is illustrated at the bottom of the diagram relative to the four-pitch combination markers 980c and 980d. Typically, multiple different markers can be used together. For example, if the markers are configured to be independently tuned to establish a reliable center position in the measurement direction, they can be used together in some embodiments of this disclosure.

[0085] Additionally, while the features and advantages of this disclosure have been discussed in relation to stitching overlay, embodiments of this disclosure are not limited thereto. Other metrological measurements can be achieved by pre-tuning image processing algorithm parameters on two corresponding sets of markers within the same field of view using a setup-obtain graph, and using the tuned data points to determine the metrological measurement value. For example, embodiments of this disclosure can be applied to metrological measurements such as alignment, stitching overlay, cross-layer overlay, distortion, focusing, or any other measurement of distance between two or more structures within a single field of view.

[0086] Figure 10 An example overlay measurement process consistent with embodiments of this disclosure is illustrated. Four exposure fields 1001a to 1001d may exist in two layers of the exposure region 1031 on the wafer. For example, the exposure region 1031 may correspond to, for example... Figure 3A The wafer W is in field 31. Layer 1 of the exposure region 1031 may include a first subfield and a second subfield 1001a / b, respectively having overlay marks 1080a / b. Layer 2 of the exposure region 1031 may include a third subfield and a fourth subfield 1001c / d, respectively having overlay marks 1080c / d. In some embodiments, all mark pairs 1001a to 1001d can be captured within a single field of view 1082 of the inspection apparatus.

[0087] Overprint markings 1080a / b can each include, for example, those above relative to... Figure 8A The two-pitch linear block markers are discussed, and the stitching overlay measurement between the first and second subfields 1001a / b in layer 1 can be performed in a similar manner. Overlay markers 1080c / d can each include, for example, those described above relative to... Figure 7 The 2-pitch 2D block markings are discussed, and the suture overlay measurement between the third and fourth subfields 1001c / d in layer 2 can be performed in a similar manner.

[0088] Furthermore, the overlay measurement between layers 1 and 2 can follow essentially the same steps as in the other embodiments discussed above, where the overlay is performed across layers rather than across suture boundaries. For example, the measured image can include at least, for example, markers 1080a and 1080c within a single field of view 1082. A first setup-obtaining graph can be determined for the first and second plurality of linear block structures in marker 1080a, and image processing algorithm parameters can be tuned to determine the optimal center position of the linear block structures in the x-direction. For example, since layer 1 is the lower layer in a given example, image processing algorithm parameters can be tuned to better identify buried features. A second setup-obtaining graph can be determined for the third and fourth plurality of 2D block structures in marker 1080c. Image processing algorithm parameters for the measured image can again be independently tuned to determine the optimal center position of the 2D block structures in the x-direction. Using the determined positions, a third setup-obtaining graph of the overlay between markers 1080a and 1080c can be used to determine overlay values, such as by taking the y-intercept of the third setup-obtaining graph. The same process can be performed on markings 1080b and 1080d.

[0089] In some embodiments, layers 1 and 2 can be acquired under different conditions, such as from different SEM detectors. For example, the SEM tool can acquire both BSE and SE simultaneously, as discussed above. The BSE image can better capture the mask features of the lower layer 1, while the SE image can better capture the surface features of the upper layer 2. Each measurement image can be tuned according to different image processing algorithms to determine the optimal settings—to obtain the overlay curve. The measurement images can then be combined at their center locations to determine the overlay value across layers 1 and 2.

[0090] Figure 11 An example process 1100 for measuring measurement parameter values ​​consistent with embodiments of this disclosure is illustrated. For example, the measurement parameters may include, for example, alignment measurements or overlay measurements. In some embodiments, measurements may be taken using, for example... Figures 1A to 1B Measurements are performed on a wafer patterned by a photolithography system 10 or 11. In some embodiments, charged particle devices (such as...) can be used. Figure 2A EBI system 100 or Figure 2B The electron beam tool 104) performs the measurement. The illustrated process 1100 can be modified to change the order of steps and include additional or fewer steps.

[0091] In step 1101, a measurement image may be acquired. The measurement image may include, for example, a charged particle beam image, such as a SEM image. In some embodiments, the measurement image may include a single field of view, such as 582, 682, 782, 882, 982, or 1082, as shown in Figures 5 to 10. The measurement image may include at least a first set of markings and a second set of markings, such as, for example, markings 580a / b, 680a / b, 680c / d, 780a / b, 780c / d, 880a / b, 880c / d, 880e / f, 980a / b, 980c / d, 1080a / b, 1080c / d, 1080a / c, or 1080b / d, as shown in Figures 5 to 10.

[0092] For example, the first set of markings may be located in a first field on the wafer, and the second set of markings may be located in a second field on the wafer. The first and second fields may include, for example, two sub-fields within an exposure area of ​​the wafer. For example, the first and second fields may include... Figure 3A The first and second fields are subfields 31a / b of field 31. Alternatively, the first and second fields may include adjacent fields 31. Further, the first and second fields may include overlapping fields in the first and second layers of the wafer. Therefore, the first set of markings and the second set of markings can be separated by, for example, a stitch boundary or other in-plane boundary, or they can be separated into two different layers.

[0093] The first set of markings may include a first plurality of structures arranged at a first pitch and a second plurality of structures separated by a second pitch. The second set of markings may include a third plurality of structures arranged at a third pitch and a fourth plurality of structures separated by a fourth pitch. In some embodiments, the first pitch may be equal to the third pitch, or the second pitch may be equal to the fourth pitch. In some embodiments, each pitch may be different.

[0094] The first and second plurality of structures can be designed using a first increment set pitch difference dP1, and the third and fourth plurality of structures can be designed using a second increment set pitch difference dP2. As mentioned above, in some embodiments, the first increment set pitch difference dP1 can be equal to the second increment set pitch difference dP2. For example, as described above relative to... Figure 5A The first and second multiple structures, as well as the third and fourth multiple structures, can be separated by a single increment set pitch difference dP.

[0095] In step 1102, a first setup-obtaining graph can be calculated to represent the offset between the first plurality of structures and the second plurality of structures. The first setup-obtaining graph can, for example, plot the design offset values ​​between the first plurality of structures and the second plurality of structures along the x-axis versus the measured offset values ​​along the y-axis. For example, the first setup-obtaining graph can be... Figure 5BThe curve in (1) or Figure 9B The curve in the figure (4) is in the form of, and as relative to Figures 5A to 10 Any of the discussions.

[0096] In step 1103, image processing algorithm parameters of the measured image can be iteratively tuned to optimize the obtained values ​​of the first set-to-obtain curve. Image processing algorithm parameters can include parameters used in any image processing algorithm, such as template matching, edge or contour finding, shape fitting, region segmentation, etc. Parameters can include: shape parameters, such as radius or line width; edge search parameters, such as threshold, derivative parameters, etc.; image enhancement parameters, such as image filter kernel parameters, grayscale tuning, or any other suitable image tuning parameters. Optimization can include adjusting the image processing algorithm parameters until a linear fit between the set value and the obtained value comprises a slope that is substantially 1 and a y-intercept that is substantially 0. For example, in some embodiments, the image processing algorithm parameters can be tuned until the slope is close to 1 within a first predetermined threshold and the y-intercept is close to 0 within a second predetermined threshold. Based on the tuned image processing algorithm parameters, the accurate center positions of the first plurality of structures or the second plurality of structures are determined.

[0097] In steps 1104 and 1105, the same process as in steps 1102 and 1103 can be performed on the second mark. For example, a second setting of offsets between the third and fourth plurality of structures can be calculated—obtaining a graph—and the measured image can be independently tuned to optimize the second setting—obtaining the obtained value of the graph. Using the tuned image processing algorithm parameters, the accurate center position of the third or fourth plurality of structures is determined.

[0098] In step 1106, a third setting—obtaining a graph—can be calculated to determine the offset between the first set of markings and the second set of markings. This third setting—obtaining a graph—can, for example, plot the design offset value between the first and second sets of markings along the x-axis and the measured offset value along the y-axis. In some embodiments, the offset value can be taken between structural subsets within each of the first and second markings. For example, as... Figure 5C As illustrated in the curve (3), offset values ​​can be taken between the second plurality of structures of the first mark 580a and the third plurality of structures of the second mark 580b. The third setting—obtaining the curve—can typically be achieved using... Figure 5C The curve in (3) or Figure 9C The curve in the figure (7) is in the form of, and as relative to Figures 5A to 10 Any of the discussions.

[0099] In step 1107, measurement or other measurement parameter values ​​can be determined based on the third setting-acquired graph. For example, the y-intercept can be used as a parameter value by linearly fitting data points in the third setting-acquired graph. This value can be any other measurement, such as alignment, overlay, distortion, focus, or distance between two or more structures within a single field of view. Further, the parameter can include placement error, edge exposure parameters, or optical proximity effects.

[0100] In step 1108, adjustments may be performed based on the measured parameter values. For example, adjustments may include tuning or calibration of the process or apparatus involved in manufacturing the measurement sample. For instance, adjustments may be performed on lithography or other semiconductor manufacturing apparatus or processes based on the measured parameter values, such as by comparing them to target, threshold, or previously measured parameter values. In some embodiments, adjustments may be made for components of the lithography apparatus, such as, for example... Figure 1A lithography system 10 or Figure 1B 11, or adjustments can be made for processes performed by such systems.

[0101] Non-transitory computer-readable media may be provided, the storage of which is used for controller (e.g.) Figure 2A Controller 109 or Figure 2B Instructions of the processor of the image processing system 290) to perform image inspection, image acquisition, platform positioning, beam focusing, electric field adjustment, beam bending, converging lens adjustment, activation of charged particle sources, beam deflection, and at least some of the steps of method 1100. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tape or any other magnetic data storage media, compact disc read-only memory (CD-ROM), any other optical data storage media, any physical media with a hole pattern, random access memory (RAM), programmable read-only memory (PROM) and erasable programmable read-only memory (EPROM), flash memory EPROM or any other flash memory, non-volatile random access memory (NVRAM), cache, registers, any other memory chip or cassette tape and its networked version.

[0102] While specific references may be made herein to the use of embodiments in the manufacture of ICs, it should be clearly understood that the embodiments have many other possible applications. For example, they can be used in the manufacture of integrated optical systems, for guiding and detecting patterns in magnetic domain memories, liquid crystal display panels, thin-film magnetic heads, etc. Those skilled in the art will understand that, in the context of such alternative applications, any use of the terms “mask,” “wafer,” or “field” herein should be considered interchangeable with the more general terms “mask,” “substrate,” and “target portion,” respectively. In this document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., wavelengths of 365, 248, 193, 157, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., wavelengths in the range of 5 to 20 nm).

[0103] The embodiments disclosed herein may be further described by the following terms. 1. A non-transitory computer-readable medium storing an instruction set executable by at least one processor of a device to cause the device to perform operations, comprising: Acquire a measurement image of a region on a substrate, which includes a first set of markings and a second set of markings; First tuning of the parameters of the first image processing algorithm for measuring the image based on the first set of markings; The first measurement value of the first set of markings is calculated based on the first tuning; A second tuning of the second image processing algorithm parameters for the measurement image is performed based on the second set of markings, and this second tuning is different from the first tuning; The second measurement value of the second set of markings is calculated based on the second tuning; and The overlay value is calculated based on the first and second measurements. 2. A non-transitory computer-readable medium according to Clause 1, wherein the measurement image is an image of a charged particle beam. 3. A non-transitory computer-readable medium according to Clause 1, wherein acquiring a measurement image includes acquiring a measurement image from a single field of view of the inspection system. 4. A non-transitory computer-readable medium pursuant to Clause 1, wherein: The first set of markings includes a first plurality of structures separated by a first pitch in a first direction and a second plurality of structures separated by a second pitch in a first direction; and The second set of markings includes a third plurality of structures separated by a third pitch in the first direction and a fourth plurality of structures separated by a fourth pitch in the first direction. 5. A non-transitory computer-readable medium pursuant to Clause 4, wherein: The first pitch is equal to the third pitch; and The second pitch is equal to the fourth pitch. 6. A non-transitory computer-readable medium pursuant to Clause 4, wherein the operation further includes: In the first comparison, the set of design offset values ​​between the first plurality of structures and the second plurality of structures is compared with the set of measured offset values ​​between the first plurality of structures and the second plurality of structures, and In the second comparison, the design offset value set between the third and fourth plurality of structures is compared with the measured offset value set between the third and fourth plurality of structures, wherein... The first tuning is performed based on the first comparison, and The second tuning is performed based on the second comparison. 7. A non-transitory computer-readable medium according to Clause 6, wherein calculating the overlay value based on the first and second measurements includes, in a third comparison, comparing a set of design offset values ​​between the first and second overlay marks with a set of measured offset values ​​between the first and second overlay marks. 8. A non-transitory computer-readable medium pursuant to Clause 4, wherein the operation further includes: Calculate the design offset and measured offset values ​​between the first plurality of structures and the second plurality of structures in a first setting in a first direction—obtain a graph, where Performing the first tuning includes adjusting the parameters of the first image processing algorithm until the first settings—the obtained curve—meets a first predetermined criterion, and The calculation of the first set of markings based on the first tuning includes determining the position of the first plurality of structures or the second plurality of structures in the first direction. 9. A non-transitory computer-readable medium pursuant to Clause 8, wherein the predetermined criteria include a first setting—obtaining either the slope or the intercept of a curve fit for a graph. 10. A non-transitory computer-readable medium pursuant to Clause 8, wherein the operation further includes: Calculate the design offset and measurement offset values ​​between the third and fourth plurality of structures in a second setting in the first direction to obtain a graph, wherein... Performing the second tuning includes adjusting the image processing algorithm parameters until the second setting—the obtained curve—meets a second predetermined criterion, and Calculating the second measurement value of the second set of markings based on the second tuning includes determining the position of the third or fourth plurality of structures in the first direction. 11. A non-transitory computer-readable medium pursuant to Clause 10, wherein the operation further includes: Calculate the design offset value and measured offset value between the first set of markings and the second set of markings in a third setting in the first direction - obtain a curve, where Calculating the parameter value based on the first and second measurements includes determining the third setting—obtaining the intercept of the curve fit of the graph. 12. A non-transitory computer-readable medium according to Clause 4, wherein one of the first plurality of structures and the second plurality of structures comprises a two-dimensional array of structures having a fifth pitch in a second direction different from the first direction. 13. The non-transitory computer-readable medium pursuant to Clause 4, wherein one of the first plurality of structures, the second plurality of structures, the third plurality of structures, or the fourth plurality of structures comprises an array of linear or circular structures. 14. The non-transitory computer-readable medium according to Clause 4, wherein the first plurality of structures comprises an array of linear structures and the second plurality of structures comprises an array of circular structures. 15. A non-transitory computer-readable medium according to Clause 1, wherein a first set of markings is located on a first side of a suture boundary, and a second set of markings is located on a second side of the suture boundary. 16. A non-transitory computer-readable medium pursuant to Clause 15, wherein the operation further includes: The local placement error of the structure in the first set of markings or the second set of markings is calculated based on the distance from the suture boundary. 17. A non-transitory computer-readable medium according to Clause 1, wherein a first set of markings is located in a first layer of a substrate and a second set of markings is located in a second layer of a substrate. 18. A non-transitory computer-readable medium pursuant to Clause 1, wherein a first tuning of the parameters of a first image processing algorithm includes one of a tuning shape fitting parameter, an edge search parameter, a template matching parameter, a region segmentation parameter, or an image quality enhancement parameter. 19. A non-transitory computer-readable medium pursuant to Clause 1, wherein a first tuning of a first image processing parameter includes one of a tuning radius, linewidth, threshold, derivative parameter, image filter kernel parameter, or grayscale tuning parameter. 20. A non-transitory computer-readable medium pursuant to Clause 1, wherein the parameter values ​​include one of alignment or overlay. 21. A non-transitory computer-readable medium pursuant to Clause 1, wherein the operation further includes: Calculate one of the following: placement error, edge exposure parameters, or optical proximity effect. 22. A non-transitory computer-readable medium pursuant to Clause 1, wherein the operation further includes: Adjustments are made to the semiconductor manufacturing process or semiconductor manufacturing apparatus based on calculated overlay values. 23. A non-transitory computer-readable medium pursuant to Clause 1, wherein: The measurement images include a first image and a second image; The parameters of the first image processing algorithm include the tuning parameters of the first image; and The parameters of the second image processing algorithm include the tuning parameters of the second image. 24. A non-transitory computer-readable medium pursuant to Clause 23, wherein: The first image includes a backscattered electron (BSE) image; and The second image includes a secondary electron (SE) image. 25. A method comprising: Acquire measurement images of the first set of markings and the second set of markings on the substrate; First tuning of the parameters of the first image processing algorithm for measuring the image based on the first set of markings; The first measurement value of the first set of markings is calculated based on the first tuning; A second tuning of the second image processing algorithm parameters for the measurement image is performed based on the second set of markings, and this second tuning is different from the first tuning; The second measurement value of the second set of markings is calculated based on the second tuning; and The overlay value is calculated based on the first and second measurements. 26. The method according to Clause 25, wherein the measured image is an image of a charged particle beam. 27. The method according to Clause 25, wherein acquiring a measurement image comprises acquiring a measurement image from a single field of view of the inspection device. 28. The method according to Clause 25, wherein: The first set of markings includes a first plurality of structures separated by a first pitch in a first direction and a second plurality of structures separated by a second pitch in a first direction; and The second set of markings includes a third plurality of structures separated by a third pitch in the first direction and a fourth plurality of structures separated by a fourth pitch in the first direction. 29. The method according to Clause 28, wherein: The first pitch is equal to the third pitch; and The second pitch is equal to the fourth pitch. 30. The method pursuant to Clause 28 also includes: In the first comparison, the set of design offset values ​​between the first plurality of structures and the second plurality of structures is compared with the set of measured offset values ​​between the first plurality of structures and the second plurality of structures, and In the second comparison, the design offset value set between the third and fourth plurality of structures is compared with the measured offset value set between the third and fourth plurality of structures, wherein... The first tuning is performed based on the first comparison, and The second tuning is performed based on the second comparison. 31. The method according to Clause 30, wherein calculating the overlay value based on the first and second measurements includes, in a third comparison, comparing the set of design offset values ​​between the first and second overlay marks with the set of measured offset values ​​of the first and second overlay marks. 32. The method pursuant to Clause 28 also includes: Calculate the design offset and measured offset values ​​between the first plurality of structures and the second plurality of structures in a first setting in a first direction—obtain a graph, where Performing the first tuning includes adjusting the parameters of the first image processing algorithm until the first settings—the obtained curve—meets a first predetermined criterion, and The calculation of the first set of markings based on the first tuning includes determining the position of the first plurality of structures or the second plurality of structures in the first direction. 33. The method according to Clause 32, wherein the predetermined criteria include a first setting—obtaining either the slope or the intercept of the curve fit of the graph. 34. The method pursuant to Clause 32 also includes: Calculate the design offset and measured offset values ​​between the third and fourth plurality of structures in a second setting in the first direction—obtain a graph, where... Performing the second tuning involves adjusting the image processing algorithm parameters until the second settings—the obtained curve—meets the second predetermined criterion, and The second measurement value calculated based on the second tuning of the second set of markings includes determining the position of a third or fourth set of structures in the first direction. 35. The method pursuant to Clause 34 also includes: Calculate the design offset and measured offset values ​​between the first and second sets of markings in a third setting in the first direction—obtain a graph, where... Calculating parameter values ​​based on the first and second measurements includes determining a third setting—obtaining the intercept of the curve fit to the graph. 36. The method according to Clause 28, wherein one of the first plurality of structures and the second plurality of structures comprises a two-dimensional array of structures having a fifth pitch in a second direction different from the first direction. 37. The method according to Clause 28, wherein one of the first plurality of structures, the second plurality of structures, the third plurality of structures, or the fourth plurality of structures comprises an array of linear or circular structures. 38. The method according to Clause 28, wherein the first plurality of structures comprises an array of linear structures and the second plurality of structures comprises an array of circular structures. 39. The method according to Clause 25, wherein the first set of markings is located on the first side of the suture boundary and the second set of markings is located on the second side of the suture boundary. 40. The method pursuant to Clause 39 also includes: The local placement error of the structure in the first or second set of markings is calculated based on the distance from the suture boundary. 41. The method according to Clause 25, wherein the first set of markings is located in the first layer of the substrate and the second set of markings is located in the second layer of the substrate. 42. The method according to Clause 25, wherein the first tuning of the first image processing algorithm parameters includes tuning one of a shape fitting parameter, an edge search parameter, a template matching parameter, a region segmentation parameter, or an image quality enhancement parameter. 43. The method according to Clause 25, wherein the first tuning of the first image processing parameter includes one of a tuning radius, linewidth, threshold, derivative parameter, image filter kernel parameter, or grayscale tuning parameter. 44. The method according to Clause 25, wherein the parameter value includes one of alignment or overlay. 45. The method pursuant to Clause 25 also includes: Calculate one of the following: placement error, edge exposure parameters, or optical proximity effect. 46. ​​The method pursuant to Clause 25 also includes: Adjustments are made to the semiconductor manufacturing process or semiconductor manufacturing apparatus based on calculated overlay values. 47. The method according to Clause 25, wherein: The measurement images include a first image and a second image; The parameters of the first image processing algorithm include the tuning parameters of the first image; and The parameters of the second image processing algorithm include the tuning parameters of the second image. 48. The method according to Clause 47, wherein: The first image includes a backscattered electron (BSE) image; and The second image includes a secondary electron (SE) image. 49. A charged particle beam device, comprising: The charged particle beam source is configured to generate a primary charged particle beam; A charged particle optical system is configured to guide a primary charged particle beam to a region on a substrate, the region including a first set of markings and a second set of markings. The controller, including one or more processors and configured to cause the charged particle beam device to perform operations, includes: Irradiate the surface of a substrate with a beam to cause charged particles to be emitted from the surface; Charged particles on the charged particle detector of the charged particle beam detection device are used to generate measurement images of a first set of markings and a second set of markings. First tuning of the parameters of the first image processing algorithm for measuring the image based on the first set of markings; The first measurement value of the first set of markings is calculated based on the first tuning; A second tuning of the second image processing algorithm parameters for the measurement image is performed based on the second set of markings, and this second tuning is different from the first tuning; The second measurement value of the second set of markings is calculated based on the second tuning; and The overlay value is calculated based on the first and second measurements. 50. The apparatus according to Clause 49, wherein the measured image is an image of a charged particle beam. 51. The apparatus according to Clause 49, wherein acquiring a measurement image comprises acquiring a measurement image from a single field of view of the inspection apparatus. 52. The apparatus pursuant to Clause 49, wherein: The first set of markings includes a first plurality of structures separated by a first pitch in a first direction and a second plurality of structures separated by a second pitch in a first direction; and The second set of markings includes a third plurality of structures separated by a third pitch in the first direction and a fourth plurality of structures separated by a fourth pitch in the first direction. 53. The apparatus pursuant to Clause 52, wherein: The first pitch is equal to the third pitch; and The second pitch is equal to the fourth pitch. 54. The apparatus pursuant to Clause 52, wherein operation further includes: In the first comparison, the set of design offset values ​​between the first plurality of structures and the second plurality of structures is compared with the set of measured offset values ​​between the first plurality of structures and the second plurality of structures, and In the second comparison, the design offset value set between the third and fourth plurality of structures is compared with the measured offset value set between the third and fourth plurality of structures, wherein... The first tuning is performed based on the first comparison, and The second tuning is performed based on the second comparison. 55. The apparatus according to Clause 54, wherein calculating the overlay value based on the first and second measurements includes, in a third comparison, comparing a set of design offset values ​​between the first and second overlay marks with a set of measured offset values ​​between the first and second overlay marks. 56. The apparatus pursuant to Clause 52, wherein operation further includes: Calculate the design offset and measured offset values ​​between the first plurality of structures and the second plurality of structures in a first setting in a first direction—obtain a graph, where Performing the first tuning includes adjusting the parameters of the first image processing algorithm until the first settings—the obtained curve—meets a first predetermined criterion, and The calculation of the first set of markings based on the first tuning includes determining the position of the first plurality of structures or the second plurality of structures in the first direction. 57. The apparatus according to Clause 56, wherein the predetermined criteria include a first setting - obtaining either the slope or the intercept of the curve fit of the graph. 58. The apparatus pursuant to Clause 56, wherein operation further includes: Calculate the design offset and measured offset values ​​between the third and fourth plurality of structures in a second setting in the first direction—obtain a graph, where... Performing the second tuning involves adjusting the image processing algorithm parameters until the second settings—the obtained curve—meets the second predetermined criterion, and The second measurement value calculated based on the second tuning of the second set of markings includes determining the position of a third or fourth set of structures in the first direction. 59. The apparatus pursuant to Clause 58, wherein operation further includes: Calculate the design offset and measured offset values ​​between the first and second sets of markings in a third setting in the first direction—obtain a graph, where... Calculating parameter values ​​based on the first and second measurements includes determining a third setting—obtaining the intercept of the curve fit to the graph. 60. The apparatus according to Clause 52, wherein one of the first plurality of structures and the second plurality of structures comprises a two-dimensional array of structures having a fifth pitch in a second direction different from the first direction. 61. The apparatus according to Clause 52, wherein one of the first plurality of structures, the second plurality of structures, the third plurality of structures, or the fourth plurality of structures comprises an array of linear or circular structures. 62. The apparatus according to Clause 52, wherein the first plurality of structures comprises an array of linear structures and the second plurality of structures comprises an array of circular structures. 63. The apparatus according to Clause 49, wherein the first set of markings is located on the first side of the suture boundary and the second set of markings is located on the second side of the suture boundary. 64. The apparatus pursuant to Clause 63, wherein operation further includes: The local placement error of the structure in the first or second set of markings is calculated based on the distance from the suture boundary. 65. The apparatus according to Clause 49, wherein the first set of markings is located in a first layer of the substrate and the second set of markings is located in a second layer of the substrate. 66. The apparatus according to Clause 49, wherein the first tuning of the first image processing algorithm parameters includes tuning one of a shape fitting parameter, an edge search parameter, a template matching parameter, a region segmentation parameter, or an image quality enhancement parameter. 67. The apparatus according to Clause 49, wherein the first tuning of the first image processing parameter includes one of a tuning radius, linewidth, threshold, derivative parameter, image filter kernel parameter, or grayscale tuning parameter. 68. The apparatus according to Clause 49, wherein the parameter value includes one of alignment or overlay. 69. The apparatus pursuant to Clause 49, wherein operation further includes: Calculate one of the following: placement error, edge exposure parameters, or optical proximity effect. 70. The apparatus pursuant to Clause 49, wherein operation further includes: Adjustments are made to the semiconductor manufacturing process or semiconductor manufacturing apparatus based on calculated overlay values. 71. The apparatus pursuant to Clause 49, wherein: The measurement images include a first image and a second image; The parameters of the first image processing algorithm include the tuning parameters of the first image; and The parameters of the second image processing algorithm include the tuning parameters of the second image. 72. The apparatus pursuant to Clause 71, wherein: The first image includes a backscattered electron (BSE) image; and The second image includes a secondary electron (SE) image. 73. A method for determining suture notches, comprising: A first set of charged particle images with markings is obtained from a first photolithographic exposure, and a second set of charged particle images with markings is obtained from a second photolithographic exposure. The first marking is located on a first side of the stitch boundary, and the second marking is located on a second side of the stitch boundary. in: The first set of markings includes a first plurality of structures separated by a first pitch and a second plurality of structures separated by a second pitch; and The second set of markings includes a third plurality of structures separated by a third pitch and a fourth plurality of structures separated by a fourth pitch. The method also includes: Determine the first relative position between the first plurality of structures and the second plurality of structures in the first set of markings; Calculate the design offset and measurement offset values ​​between the first set of multiple structures and the second set of multiple structures to obtain a graph; Optimize the first image processing algorithm until the first setting—the obtained curve—meets the first specified criterion; The optimized first image processing algorithm is applied to the first set of markings in the charged particle image; Determine the second relative position between the third and fourth structures in the second set of markings; A second setting is used to calculate the design offset and measurement offset values ​​between the third and fourth multiple structures to obtain a graph; Optimize the second image processing algorithm until the second setting—the obtained curve—meets the second specified criterion; The optimized second image processing algorithm is applied to the second set of markings in the charged particle image; A third setting calculates the design offset and measured offset values ​​between the first and second sets of markings—to obtain a graph; and Based on the third setting - the intercept of the obtained curve is used to determine the suture set value. 74. The method according to Clause 73, wherein acquiring a measurement image comprises acquiring a measurement image from a single field of view of the inspection device. 75. The method according to Clause 73, wherein: The first pitch is equal to the third pitch; and The second pitch is equal to the fourth pitch. 76. The method according to Clause 73, wherein the first specified criterion includes the first setting—obtaining either the slope or the intercept of the curve fit of the graph. 77. The method according to Clause 73, wherein the second specified criterion includes the second setting—obtaining either the slope or the intercept of the curve fit of the graph. 78. The method according to Clause 73, wherein one of the first plurality of structures and the second plurality of structures comprises a two-dimensional array of structures having a fifth pitch in a second direction different from the first direction. 79. The method according to Clause 73, wherein one of the first plurality of structures, the second plurality of structures, the third plurality of structures, or the fourth plurality of structures comprises an array of linear or circular structures. 80. The method according to Clause 73, wherein the first plurality of structures comprises an array of linear structures and the second plurality of structures comprises an array of circular structures. 81. The method pursuant to Clause 73 also includes: The local placement error of the structure in the first or second set of markings is calculated based on the distance from the suture boundary. 82. The method according to Clause 73, wherein the first set of markings is located in the first layer of the substrate and the second set of markings is located in the second layer of the substrate. 83. The method according to Clause 73, wherein optimizing the first image processing algorithm includes tuning one of shape fitting parameters, edge search parameters, template matching parameters, region segmentation parameters, or image quality enhancement parameters. 84. The method according to Clause 73, wherein optimizing the first image processing algorithm includes one of tuning radius, line width, threshold, derivative parameter, image filter kernel parameter, or grayscale tuning parameter. 85. The method according to Clause 73 also includes determining one of placement error, edge exposure parameters, or optical proximity effect. 86. The method pursuant to Clause 73 also includes: Adjustments are made to the semiconductor manufacturing process or semiconductor manufacturing apparatus based on calculated overlay values. 87. The method according to Clause 73, wherein: The charged particle image includes a first image and a second image; Optimizing the first image processing algorithm includes tuning the first image processing algorithm relative to the first image; and Optimizing the second image processing algorithm includes tuning the second image processing algorithm relative to the second image. 88. The method according to Clause 87, wherein: The first image includes a backscattered electron (BSE) image; and The second image includes a secondary electron (SE) image.

[0104] The block diagrams in the accompanying drawings 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 this regard, each block in the diagrams may represent certain arithmetic or logical operations that can be implemented using hardware such as electronic circuits. A block may also represent a module, segment, or code portion, including one or more executable instructions for implementing a specified logical function. It should be understood that in some alternative implementations, the functions indicated in the blocks may not occur in the order mentioned in the drawings. For example, two blocks shown consecutively may be executed or implemented substantially concurrently, or the two blocks may sometimes be executed in reverse order, depending on the functionality involved. Some blocks may also be omitted. It should also be understood that each block of the block diagram, and combinations of blocks, may be implemented by a dedicated hardware-based system (performing the specified function or action) or a combination of dedicated hardware and computer instructions.

[0105] It should be understood that the embodiments of this disclosure are not limited to the precise constructions described above and illustrated in the accompanying drawings, and various modifications and changes can be made without departing from its scope. This disclosure has been described in conjunction with various embodiments, and other embodiments of the invention will be apparent to those skilled in the art in light of the specification and practice of the invention disclosed herein. The specification and examples are intended to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

Claims

1. A non-transitory computer-readable medium storing an instruction set, the instruction set being executable by at least one processor of a device to cause the device to perform operations, the operations including: Acquire a measurement image of a region on a substrate, the region including a first set of markings and a second set of markings; Perform the first tuning of the first image processing algorithm parameters for the measured image of the first set of markings; The first measurement value of the first set of engraved marks is calculated based on the first tuning; Perform a second tuning of the second image processing algorithm parameters for the second set of markings on the measured image, the second tuning being different from the first tuning; The second measurement value of the second set of markings is calculated based on the second tuning; as well as The overlay value is calculated based on the first measurement value and the second measurement value.

2. The non-transitory computer-readable medium according to claim 1, wherein the measurement image is a charged particle beam image. Acquiring the measurement image includes acquiring the measurement image from a single field of view of the inspection device, and each of the first image and the second image includes one of a backscattered electron (BSE) image and a secondary electron (SE) image.

3. The non-transitory computer-readable medium according to claim 1, wherein: The first set of markings includes: a first plurality of structures arranged at a first pitch in a first direction, and a second plurality of structures arranged at a second pitch in the first direction; and The second set of markings includes: a third plurality of structures arranged at a third pitch in the first direction, and a fourth plurality of structures arranged at a fourth pitch in the first direction, and in: The first pitch is equal to the third pitch; and The second pitch is equal to the fourth pitch.

4. The non-transitory computer-readable medium of claim 3, wherein the operation further comprises: In the first comparison, the set of design offset values ​​between the first plurality of structures and the second plurality of structures is compared with the set of measured offset values ​​between the first plurality of structures and the second plurality of structures. In the second comparison, the design offset value set between the third and fourth plurality of structures is compared with the measured offset value set between the third and fourth plurality of structures, wherein... The first tuning is performed based on the first comparison, and The second tuning is performed based on the second comparison.

5. The non-transitory computer-readable medium of claim 4, wherein calculating the overlay value based on the first measurement value and the second measurement value comprises: In the third comparison, the set of design offset values ​​between the first set of markings and the second set of markings is compared with the set of measured offset values ​​between the first set of markings and the second set of markings.

6. The non-transitory computer-readable medium of claim 4, wherein the operation further comprises: Calculate the design offset and measurement offset values ​​between the first plurality of structures and the second plurality of structures in a first setting along the first direction to obtain a graph. in Performing the first tuning includes: adjusting the parameters of the first image processing algorithm until the first settings-obtained curve satisfies a first predetermined criterion, and Calculating the first measurement value of the first set of markings based on the first tuning includes: determining the position of the first plurality of structures or the second plurality of structures in the first direction, wherein the predetermined criterion includes either the slope or the intercept of the curve fitting obtained from the first setting. Calculate the design offset and measurement offset values ​​between the third and fourth plurality of structures in a second setting in the first direction to obtain a graph, wherein... Performing the second tuning includes: adjusting the image processing algorithm parameters until the second setting—the obtained curve—meets a second predetermined criterion, and The calculation of the second measurement value of the second set of markings based on the second tuning includes: determining the position of the third or fourth plurality of structures in the first direction; and Calculate the design offset and measured offset values ​​between the first set of markings and the second set of markings in a third setting in the first direction—to obtain a graph, where... Calculating the parameter value based on the first and second measurements includes: determining the third setting - obtaining the intercept of the curve fitting of the curve graph.

7. The non-transitory computer-readable medium of claim 4, wherein one of the first plurality of structures and the second plurality of structures comprises a two-dimensional structure array having a fifth pitch in a second direction different from the first direction.

8. The non-transitory computer-readable medium of claim 4, wherein one of the first plurality of structures, the second plurality of structures, the third plurality of structures, or the fourth plurality of structures comprises a linear or circular array of structures.

9. The non-transitory computer-readable medium of claim 4, wherein the first plurality of structures comprises a linear structure array, and the second plurality of structures comprises a circular structure array.

10. The non-transitory computer-readable medium of claim 1, wherein the first set of markings is located on a first side of the suture boundary, and the second set of markings is located on a second side of the suture boundary.

11. The non-transitory computer-readable medium of claim 10, wherein the operation further comprises: Based on the distance from the suture boundary, calculate the local placement error of the structure in the first set of markings or the second set of markings.

12. The non-transitory computer-readable medium of claim 1, wherein the first set of markings is located in a first layer of the substrate, and the second set of markings is located in a second layer of the substrate.

13. The non-transitory computer-readable medium according to claim 1, wherein the measurement image comprises a first image and a second image; The first image processing algorithm parameters include the tuning parameters of the first image; and The second image processing algorithm parameters include the tuning parameters of the second image, and the first tuning of the first image processing algorithm parameters includes tuning one of the following: shape fitting parameters, edge search parameters, template matching parameters, region segmentation parameters, or image quality enhancement parameters.

14. The non-transitory computer-readable medium of claim 1, wherein the parameter value includes one of the following: alignment or overlay.

15. The non-transitory computer-readable medium of claim 1, wherein the operation further comprises: Calculate one of the following: placement error, edge exposure parameters, or optical proximity effect.

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