Real-time scatter overlay metrology target

Abstract

According to one or more embodiments of the present disclosure, a metrology target is disclosed. The metrology target includes a first set of pattern elements having a first pitch, wherein the first set of pattern elements includes segmented pattern elements. The metrology target includes a second set of pattern elements having a second pitch, wherein the second set of pattern elements includes segmented pattern elements. The metrology target includes a third set of pattern elements having a third pitch, wherein the third set of pattern elements includes segmented pattern elements.

Description

Technical Field

[0001] This disclosure generally relates to superposition metrology, and more specifically to real-time scattering superposition metrology. Background Technology

[0002] Superimposed metrological targets are typically designed to provide diagnostic information about the alignment of multiple layers of a sample by characterizing superimposed targets with target features positioned on the layers of the sample of interest. Furthermore, the superimposed alignment of multiple layers is typically determined by summing superimposed measurements of multiple superimposed targets at various locations across the sample. Some superimposed metrological targets (e.g., scattering superimposed (SCOL) metrological targets) contain periodic structures configured to produce diffraction patterns that can be analyzed to determine metrological measurements. The diffraction pattern is generated by illuminating the periodic structure along the measurement direction of the periodic structure (e.g., an element perpendicular to the grating). A typical SCOL metrological target contains a periodic structure within multiple cells, wherein the periodic structure is configured for illumination along at least two measurement directions. However, a typical SCOL metrological target containing multiple cells occupies a larger surface area of ​​the sample, and metrological measurements using such targets require more time compared to SCOL metrological targets with cells configured for metrological measurements along a single measurement direction.

[0003] Therefore, it would be advantageous for SCOL metrology targets to have units configured to perform metrological measurements along a single measurement direction. Summary of the Invention

[0004] According to one or more embodiments of this disclosure, a measurement target is disclosed. In one embodiment, the measurement target includes a first unit. In another embodiment, the first unit includes a first portion of a first set of pattern elements formed along a first measurement direction, wherein the first set of pattern elements includes segmented pattern elements having a first pitch. In another embodiment, the measurement target includes a first portion of a second set of pattern elements formed along the first measurement direction, wherein the second set of pattern elements includes segmented pattern elements having a second pitch. In another embodiment, the measurement target includes a first portion of a third set of pattern elements formed along the first measurement direction, wherein the third set of pattern elements includes segmented pattern elements having a third pitch.

[0005] According to one or more embodiments of this disclosure, a system is disclosed. In one embodiment, the system includes one or more controllers having one or more processors communicatively coupled to one or more metrology subsystems, wherein the one or more processors are configured to execute a set of program instructions maintained in memory, wherein the set of program instructions are configured to cause the one or more processors to: receive from the one or more metrology subsystems one or more signals indicating illumination emitted from a first set of pattern elements, a second set of pattern elements, and a third set of pattern elements from one or more metrology targets of a sample, wherein the one or more metrology targets of the sample include: a first unit, the first unit including a first portion of the first set of pattern elements formed along a first measurement direction. The first set of pattern elements includes segmented pattern elements with a first pitch; a first portion of a second set of pattern elements formed along the first measurement direction, wherein the second set of pattern elements includes segmented pattern elements with a second pitch; and a first portion of a third set of pattern elements formed along the first measurement direction, wherein the third set of pattern elements includes segmented pattern elements with a third pitch; a first superimposed measurement is obtained based on the first set of pattern elements; a second superimposed measurement is obtained based on the second set of pattern elements; a third superimposed measurement is obtained based on the third set of pattern elements; and a superimposed error is determined based on at least two of the first superimposed measurement, the second superimposed measurement, or the third superimposed measurement.

[0006] According to one or more embodiments of this disclosure, a method for measuring superposition is disclosed. In one embodiment, the method includes illuminating a sample having one or more metrological targets. In another embodiment, the method includes detecting one or more signals indicating illumination emitted from a first set of pattern elements, a second set of pattern elements, and a third set of pattern elements of the one or more metrological targets of the sample, wherein the one or more metrological targets of the sample include: a first unit comprising a first portion of a first set of pattern elements formed along a first measurement direction, wherein the first set of pattern elements includes segmented pattern elements having a first pitch; a first portion of a second set of pattern elements formed along the first measurement direction, wherein the second set of pattern elements includes segmented pattern elements having a second pitch; and a first portion of a third set of pattern elements formed along the first measurement direction, wherein the third set of pattern elements includes segmented pattern elements having a third pitch. In another embodiment, the method includes acquiring a first superposition measurement based on the one or more signals indicating illumination emitted from the first set of pattern elements. In another embodiment, the method includes acquiring a second superposition measurement based on the one or more signals indicating illumination emitted from the second set of pattern elements. In another embodiment, the method includes acquiring a third superposition measurement based on one or more signals indicating illumination emitted from the third set of pattern elements. In another embodiment, the method includes determining a superposition error based on at least one of the first superposition measurement, the second superposition measurement, or the third superposition measurement.

[0007] According to one or more embodiments of this disclosure, a method for forming a measurement target is disclosed. In one embodiment, the method includes forming a first unit comprising a first portion of a first set of pattern elements formed along a first measurement direction, wherein the first set of pattern elements includes segmented pattern elements having a first pitch; a first portion of a second set of pattern elements formed along the first measurement direction, wherein the second set of pattern elements includes segmented pattern elements having a second pitch; and a first portion of a third set of pattern elements formed along the first measurement direction, wherein the third set of pattern elements includes segmented pattern elements having a third pitch. Attached Figure Description

[0008] Those skilled in the art will better understand the many advantages of this disclosure by referring to the accompanying drawings.

[0009] Figure 1A This is a top view of a measurement target according to one or more embodiments of the present disclosure.

[0010] Figure 1B This is a top view of a measurement target according to one or more embodiments of the present disclosure.

[0011] Figure 1C This is a top view of a measurement target according to one or more embodiments of the present disclosure.

[0012] Figure 1D This is a side view of a measurement target according to one or more embodiments of the present disclosure.

[0013] Figure 2 This is a conceptual view of a metering system according to one or more embodiments of the present disclosure.

[0014] Figure 3 A conceptual view illustrating a metering subsystem according to one or more embodiments of this disclosure.

[0015] Figure 4 This is a flowchart depicting the steps of a method for superimposing measurement samples according to one or more embodiments of the present disclosure.

[0016] Figure 5 This is a process flow diagram depicting the steps of a method for forming a measurement target according to one or more embodiments of the present disclosure. Detailed Implementation

[0017] Semiconductor devices can be formed as multiple printed layers of patterned material on a substrate. Each printed layer can be fabricated through a series of process steps (e.g., but not limited to, one or more material deposition steps, one or more photolithography steps, or one or more etching steps). In some manufacturing processes, one or more photoresist materials can be used to form the printed layers. For example, a photoresist material can be deposited onto a substrate. The photoresist material can then be exposed to illumination, where the illumination creates a latent target pattern on the photoresist material. The latent target pattern (or a developed target pattern formed from the latent target pattern) can then be used as a pattern for one or more photolithography and / or one or more etching steps configured to form a final target pattern on the substrate for use in overlay and / or metrology applications. In other manufacturing processes, a photoresist material is exposed to illumination to create a latent target pattern on the photoresist material, and the latent target pattern (or a developed target pattern formed from the latent target pattern) is used in overlay and / or metrology applications.

[0018] During manufacturing, each printed layer must typically be manufactured within selected tolerances to correctly construct the final device. For example, the relative placement of printed elements in each layer (e.g., stacking or stacking parameters) must be well characterized and controlled relative to previously manufactured layers. Therefore, metrological targets can be created on one or more printed layers to achieve efficient characterization of layer stacking. Thus, deviations in the stacking target features on printed layers can represent deviations in the printed characteristics of the printed device features on those layers. Furthermore, the stacking measured in a manufacturing step (e.g., after the manufacture of one or more sample layers) can be used to generate calibrable amounts for accurately aligning process tools (e.g., lithography tools or the like) used to manufacture additional sample layers in subsequent manufacturing steps.

[0019] A metrological target typically comprises well-defined printed elements designed to provide an accurate representation of one or more printing characteristics. In this respect, the measurable characteristics of the printed elements of a metrological target (e.g., via a metrological tool) can represent printed apparatus elements associated with a manufactured device. Furthermore, a metrological target is typically characterized by having one or more measurement units, each containing printed elements in one or more layers on a sample. Thus, metrological measurements can be based on any combination of measurements of the size, orientation, or position (e.g., pattern placement) of the printed elements in or between individual units. For example, one or more units of a superimposed metrological target can contain printed elements on two or more sample layers, the printed elements being arranged such that the relative position of the elements in each layer can indicate offset errors (e.g., pattern placement errors (PPE)) in a particular layer or superposition errors associated with registration errors between sample layers. By way of another example, process-sensitive metrology targets may be contained in a printed element on a single sample layer, wherein one or more characteristics of the printed element (e.g., width or critical dimension (CD), sidewall angle, position or the like) indicate one or more of the following process metrics: illumination dose during the lithography step, or the focal position of the sample in the lithography tool during the lithography step.

[0020] Overlay metrology is typically performed by manufacturing one or more overlay targets across samples, where each overlay target contains features in the sample layer of interest that are manufactured simultaneously with features associated with the manufactured device or component. In this respect, overlay error measured at the location of the overlay target can represent overlay error of the device features. Therefore, overlay measurements can be used to monitor and / or control any number of manufacturing tools to maintain device production according to specified tolerances. For example, an overlay measurement of the current layer relative to a previous layer on a sample can be used as feedback data for monitoring and / or mitigating manufacturing deviations of the current layer on additional samples within a batch. By another example, an overlay measurement of the current layer relative to a previous layer on a sample can be used as feedforward data to manufacture subsequent layers on the same sample in a manner that takes into account existing layer alignment.

[0021] Stacking targets typically include features specifically designed to be sensitive to stacking errors between layers of interest. Stacking measurements can then be performed by characterizing the stacking targets using a stacking metrology tool and applying an algorithm to determine the stacking error on the samples based on the output of the metrology tool.

[0022] Regardless of the stacking measurement technique, stacking metrology tools are typically configured according to a recipe containing a set of measurement parameters used to generate a stacking signal. For example, the recipe for a stacking metrology tool may include (but is not limited to) illumination wavelength, detected wavelength of radiation emitted from the sample, size of the illumination spot on the sample, angle of incident illumination, polarization of the incident illumination, position of the incident illumination beam on the stacking target, position of the stacking target in the focal volume of the stacking metrology tool, or the like. Therefore, a stacking recipe may contain a set of measurement parameters suitable for generating a stacking signal applicable to determining the stacking of two or more sample layers.

[0023] Superposition metrology tools can utilize various techniques to determine the superposition of sample layers. For example, image-based superposition metrology tools illuminate the superposition target (e.g., an advanced imaging metrology (AIM) target, a box-in-box metrology target, or the like) and capture a superposition signal containing images of superposition target features located on different sample layers. Therefore, superposition can be determined by measuring the relative positions of the superposition target features. As another example, scattering-based superposition metrology tools illuminate the superposition target (e.g., a grating-on-grating metrology target, or the like) and capture a superposition signal containing the angular distribution of radiation emitted from the superposition target associated with diffraction, scattering, and / or reflection of the illumination beam. Therefore, superposition can be determined based on a model of the interaction between the illumination beam and the superposition target.

[0024] As should be understood herein, various superposition metrology tools can be used to measure superpositions. For example, optical metrology tools (e.g., light-based metrology tools that use electromagnetic radiation for illumination and / or detection) can provide high-throughput superposition measurements using a variety of techniques, such as (but not limited to) determining the relative positions of spatially separated features on multiple layers in an image, directly measuring PPE on multiple layers, or determining superposition scattering measurements based on light scattered and / or diffracted from diffraction gratings on multiple layers. For the purposes of this disclosure, the terms “optical metrology tool,” “optical metrology technique,” ​​and the like refer to metrology tools and techniques that use electromagnetic radiation of any wavelength (e.g., but not limited to, X-ray wavelengths, extreme ultraviolet (EUV) wavelengths, vacuum ultraviolet (VUV) wavelengths, deep ultraviolet (DUV) wavelengths, ultraviolet (UV) wavelengths, visible light wavelengths, or infrared (IR) wavelengths). Systems, methods, and apparatuses related to overlay measurements are generally described in the following: U.S. Patent No. 8,330,281, issued December 11, 2012, entitled “Overlay Marks, Methods of Overlay Mark Design and Methods of Overlay Measurements”; U.S. Patent No. 9,476,698, issued October 25, 2016, entitled “Periodic Patchters and Technique to Control Misalignment Between Two Layers”; and U.S. Patent No. 9,476,698, issued June 2, 2009, entitled “Apparatus and Methods for Determining Overlay of Structure Shaping Rotational or Mirror Symmetry”. U.S. Patent No. 7,541,201, entitled “Symmetry”; U.S. Patent Publication No. 2013 / 0035888, published on February 7, 2013, entitled “Method and System for Providing Aquatic Metrics for Improved Process Control”; and U.S. Patent No. 9,214,317, published on December 15, 2015, entitled “System and Method of Scanning Electron Microscopy Overlay Metrology”.U.S. Patent No. 10,527,951B2, issued January 7, 2020, entitled "Compound Imaging Metrological Targets"; U.S. Patent No. 10,190,979B2, issued January 29, 2019, entitled "Metrological Imaging Targets Having Reflection-Symmetric Pairs of Reflection-Asymmetric Structures"; and U.S. Patent Application No. 10,190,979B2, filed June 27, 2016, entitled "Apparatus and Method for the Measurement of Pattern Placement and Size of Pattern and Computer Program". The entire contents of PCT application No. PCT / US2016 / 039531, entitled "THEREFOR", are incorporated herein by reference.

[0025] As used throughout this disclosure, the term "sample" generally refers to a substrate (e.g., a wafer or the like) formed of a semiconductor or non-semiconductor material. For example, semiconductor or non-semiconductor materials may include (but are not limited to) monocrystalline silicon, gallium arsenide, and indium phosphide. A sample may comprise one or more layers. For example, such layers may include (but are not limited to) resists (including photoresists), dielectric materials, conductive materials, and semiconducting materials. Many different types of such layers are known in the art, and the term "sample" as used herein is intended to cover samples on which all types of such layers can be formed. The one or more layers formed on a sample may be patterned or unpatterned. For example, a sample may comprise multiple dies, each having repeatable patterned features. The formation and processing of such material layers can ultimately result in a finished device. Many different types of devices can be formed on a sample, and the term "sample" as used herein is intended to cover samples on which any type of device known in the art is manufactured. Furthermore, for the purposes of this disclosure, the terms "sample" and "wafer" should be interpreted as interchangeable. Furthermore, for the purposes of this disclosure, the terms patterning device, mask, and photomask should be interpreted as interchangeable.

[0026] Figure 1AThis is a top view of a metrological target 100 according to one or more embodiments of the present disclosure. The metrological target 100 may include a first unit 101. The first unit 101 may include a first portion 102a of a first set of pattern elements 102. The first set of pattern elements 102 may be compatible with any metrological mode known in the art, including (but not limited to) any scattering-based superposition (SCOL) metrological mode. In this respect, the first set of pattern elements 102 may be configured to include periodic and / or segmented structures (e.g., grating-on-grating structures, or any structures known in the art suitable for diffracting, scattering, and / or reflecting illumination beams) for metrological purposes using SCOL-based metrological methods. The first set of pattern elements 102 may have a first pitch (e.g., the periodic distance between repeating reference features of the first set of pattern elements 102). By another example, the first set of pattern elements 102 is compatible with any image-based overlay metrology mode, including (but not limited to) advanced imaging metrology (AIM) mode, frame-to-frame metrology mode, or any other metrology mode known in the art suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers). A first portion 102a of the first set of pattern elements 102 can be configured for metrology along a first measurement direction. For example, the first portion 102a of the first set of pattern elements 102 can be configured for measurement along the y-direction.

[0027] The first unit 101 may include a first portion 104a of the second set of pattern elements 104. The second set of pattern elements 104 may be compatible with any metrology mode known in the art along the first measurement direction, including (but not limited to) any scattering-based superposition (SCOL) metrology mode. In this regard, the second set of pattern elements 104 may be configured to include periodic and / or segmented structures (e.g., grating-on-grating structures, or any structures known in the art suitable for diffraction, scattering, and / or reflection of illumination beams) for metrology using SCOL-based metrology methods. The second set of pattern elements 104 may have a second pitch (e.g., the periodic distance between repeating reference features of the second set of pattern elements 104). By another example, the second set of pattern elements 104 may be compatible with any image-based superposition metrology mode, including (but not limited to) advanced imaging metrology (AIM) modes, frame-to-frame metrology modes, or any other metrology mode known in the art suitable for capturing superimposed signals (e.g., images of superimposed target features located on different sample layers). It should be noted specifically that in some embodiments, the second pitch may not be equivalent to the first pitch.

[0028] The first unit 101 may include a first portion 106a of a third set of pattern elements 106. The third set of pattern elements 106 may be compatible with any metrology mode known in the art along a first measurement direction, including (but not limited to) any scattering-based superposition (SCOL) metrology mode. In this respect, the third set of pattern elements 106 may be configured to include periodic and / or segmented structures (e.g., grating-on-grating structures, or any structures known in the art suitable for diffraction, scattering, and / or reflection of illumination beams) for metrology using SCOL-based metrology methods. The third set of pattern elements 106 may have a third pitch (e.g., the periodic distance between repeating reference features of the third set of pattern elements 106). By another example, the third set of pattern elements 106 may be compatible with any image-based superposition metrology mode, including (but not limited to) advanced imaging metrology (AIM) modes, frame-to-frame metrology modes, or any other metrology mode known in the art suitable for capturing superimposed signals (e.g., images of superimposed target features located on different sample layers). The third set of pattern elements 106 may have a third pitch. It should be noted specifically that in some embodiments, the third pitch may not be equivalent to either the first pitch or the second pitch.

[0029] Figure 1B This is a top view of a measurement target 100 according to one or more embodiments of the present disclosure. The measurement target 100 may include a second unit 103. The second unit 103 may include a second portion 102b of a first set of pattern elements 102. The second portion 102b of the first set of pattern elements 102 may be configured for measurement along a second measurement direction. For example, the second portion 102b of the first set of pattern elements 102 may be configured for measurement along the x-direction. The second unit 103 may include a second portion 104b of a second set of pattern elements 104. The second portion 104b of the second set of pattern elements 104 may be configured for measurement along the second measurement direction. The second unit 103 may include a second portion 106b of a third set of pattern elements 106. The second portion 106b of the third set of pattern elements 106 may be configured for measurement along the second measurement direction.

[0030] The first unit 101 and the second unit 103 can be formed such that the first unit 101 and the second unit 103 are adjacent to each other. For example, as Figure 1BAs shown, the second unit 103 may be formed to the side of the first unit 101. It should be noted that each of the first unit 101 and the second unit 103 may be configured such that each of the first and second measurement directions is perpendicular to each other. In this respect, the first unit 101 and the second unit 103 may be four-fold rotationally symmetric. In another embodiment, the first unit 101 and the second unit 103 may be two-fold rotationally symmetric. In some embodiments, the size of the first unit 101 and / or the second unit 103 may allow the measurement target 100 to be used in a small region of the sample. For example, in some embodiments, the measurement target 100 may be configured to include only the first unit 101 to comply with spatial considerations regarding the sample. In other embodiments, the measurement target 100 may be configured to include only the second unit 103 to comply with spatial considerations regarding the sample. In other embodiments, the measurement target 100 may be configured to include both the first unit 101 and the second unit 103 to comply with spatial considerations regarding the sample.

[0031] In some embodiments, such as Figure 1C and 1D As shown, the measurement target 100 can be configured to occupy a small amount of surface area on the sample. For example, the measurement target 100 can be configured such that the first unit 101 and the second unit 103 form a "grating on grating" structure. By another example, the first unit 101 can be formed in a first layer of the measurement target 100, and the second unit 103 can be formed in a second layer of the measurement target 100. In this respect, the second unit 103 can be formed on top of the first unit 101 (e.g., along the z-direction) such that the first portion 102a of the first group of pattern elements, the first portion 104a of the second group of pattern elements, and the first portion 106a of the third group of pattern elements can form a "grating on grating" structure occupying a small surface area on the sample.

[0032] It should be noted that the pattern elements of the metrological target 100 (e.g., the first element 101 and / or the second element 103) may be configured such that incident radiation directed to one or more portions of the first element 101 and / or the second element 103 may be diffracted by one or more portions of the first set of pattern elements 102, the second set of pattern elements 104 and / or the third set of pattern elements 106, and the diffracted radiation may be detected and analyzed (e.g., by one or more metrological subsystems) to determine one or more superimposed measurements based on the diffracted radiation and / or one or more signals indicating the diffracted radiation.

[0033] It should be noted that embodiments of this disclosure that include (but are not limited to) components of the metrology target 100 (e.g., first unit 101, second unit 103, first group of pattern elements 102, second group of pattern elements 104, and / or third group of pattern elements 106) can be configured to reduce the amount of time required to perform superimposed measurements. For example, because each of the first portion 102a of the first group of pattern elements, the first portion 104a of the second group of pattern elements, and the first portion 106a of the third group of pattern elements is configured for measurement along a first measurement direction, the configuration of the first unit 101 can reduce the time required for the metrology subsystem to capture signals from each of the pattern elements of the first unit 101. In this respect, by forming each of the portions of the pattern elements of the first unit 101 along the first measurement direction, the metrology subsystem can capture signals from such pattern elements without adjusting one or more measurement parameters associated with the measurement direction (i.e., the metrology subsystem can receive signals from the metrology target 100 only along one measurement direction relative to a given unit).

[0034] Figure 2 A simplified block diagram of a metrology system 200 according to one or more embodiments of the present disclosure is provided. In one embodiment, the metrology system 200 includes one or more metrology subsystems 202. The one or more metrology subsystems 202 may be configured to operate in an imaging mode or a non-imaging mode. For example, in imaging mode, individual superimposed target elements may be resolved within an illuminated spot on the sample (e.g., as part of a bright-field image, a dark-field image, a phase-contrast image, or the like). By another example, the one or more metrology subsystems 202 may operate as a scattering-based superposition (SCOL) metrology tool, wherein radiation from the sample is analyzed at the pupil plane to characterize the angular distribution of radiation from the sample (e.g., associated with scattering and / or diffraction of radiation by the sample).

[0035] One or more metrology subsystems 202 can direct illumination to the sample and further collect radiation emitted from the sample to generate a superposition signal suitable for determining the superposition of two or more sample layers. The one or more metrology subsystems may include any type of superposition metrology tool known in the art for generating a superposition signal suitable for determining the superposition associated with a superposition target on the sample, including (but not limited to) any optical metrology tool (e.g., Advanced Imaging Metrology (AIM) tool, Advanced Imaging in Die (AIMid) tool, Triple Advanced Imaging Metrology (Triple AIM) tool, and the like), any particle-based metrology tool (e.g., electron beam metrology tool), or scattering-based superposition (SCOL) metrology tool. It should be noted that embodiments of this disclosure are not limited to a metrology system 200 having only one metrology subsystem 202, and a metrology system 200 may include at least two metrology subsystems. For example, a metrology system 200 may include an optical metrology tool and a scattering-based superposition (SCOL) metrology tool.

[0036] One or more metrology subsystems 202 may be configured to generate a superposition signal based on any number of recipes defined for acquiring a superposition signal suitable for determining the superposition target. For example, the recipes of one or more metrology subsystems 202 may include (but are not limited to) illumination wavelength, detected wavelength of radiation emitted from the sample, size of the illumination spot on the sample, angle of incident illumination, polarization of the incident illumination, wave plane of the incident beam, position of the incident illumination beam on the superposition target, position of the superposition target in the focal volume of the superposition metrology tool, or the like.

[0037] In another embodiment, the overlay metering system 200 includes a controller 204 communicatively coupled to one or more metering subsystems 202. The controller 204 may be configured to direct one or more metering subsystems 202 to generate overlay signals based on one or more selected recipes. The controller 204 may be further configured to receive data from one or more metering subsystems 202, including (but not limited to) the overlay signals. Additionally, the controller 204 may be configured to determine an overlay associated with an overlay target based on the acquired overlay signals.

[0038] In another embodiment, controller 204 includes one or more processors 206. For example, one or more processors 206 may be configured to execute a set of program instructions held in memory device 208 or memory. The one or more processors 206 of controller 204 may include any processing element known in the art. In this sense, one or more processors 206 may include any microprocessor-type device configured to execute algorithms and / or instructions. Furthermore, memory device 208 may include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 206. For example, memory device 208 may include non-transitory memory media. As additional examples, memory device 208 may include (but is not limited to) read-only memory, random access memory, magnetic or optical memory devices (e.g., magnetic disks), magnetic tape, solid-state drives, and the like. It should be further noted that memory device 208 may be housed together with one or more processors 206 in a common controller housing.

[0039] In one embodiment, metrology subsystem 202 can direct illumination to a sample and further collect radiation emitted from the sample to generate a superposition signal suitable for determining the superposition of two or more sample layers. Metrology subsystem 202 can be configured to generate the superposition signal based on any number of recipes that define measurement parameters used to acquire the superposition signal suitable for determining the superposition target. For example, the recipes of metrology subsystem 202 may include (but are not limited to) illumination wavelength, detected wavelength of radiation emitted from the sample, spot size of illumination on the sample, angle of incident illumination, polarization of the incident illumination, position of the incident illumination beam on the superposition target, position of the superposition target in the focal volume of the superposition metrology tool, or the like.

[0040] In one embodiment, such as Figure 3 As shown, one or more metrology subsystems 202 may include an optical metrology subsystem 202, such as a metrology subsystem containing optical metrology tools. The optical metrology subsystem 202 may include any type of optical metrology tool known in the art for generating metrological data from samples, including (but not limited to) optical metrology tools configured to generate and / or detect optical illumination beams having X-ray, ultraviolet (UV), infrared (IR), or visible light wavelengths. By another example, one or more metrology subsystems 202 may include an advanced imaging metrology (AIM) tool, an advanced in-die imaging metrology (AIMid) tool, or a triple advanced imaging metrology (triple AIM) tool.

[0041] In one embodiment, one or more metering subsystems 202 may include an optical illumination source 324 configured to generate an optical illumination beam 326. The optical illumination beam 326 may include radiation of one or more selected wavelengths, including (but not limited to) X-rays, ultraviolet (UV) light, visible light, or infrared (IR) light.

[0042] Optical illumination source 324 may comprise any type of illumination source suitable for providing optical illumination beam 326. In one embodiment, optical illumination source 324 is a laser source. For example, optical illumination source 324 may comprise (but is not limited to) one or more narrowband laser sources, broadband laser sources, supercontinuum laser sources, white light laser sources, or the like. In this respect, optical illumination source 324 may provide optical illumination beam 326 with high coherence (e.g., high spatial coherence and / or temporal coherence). In another embodiment, optical illumination source 324 comprises a laser continuous plasma (LSP) source. For example, optical illumination source 324 may comprise (but is not limited to) an LSP lamp, LSP bulb, or LSP chamber suitable for housing one or more elements capable of emitting broadband illumination when excited into a plasma state by a laser source. In another embodiment, optical illumination source 324 comprises a lamp source. For example, optical illumination source 324 may comprise (but is not limited to) an arc lamp, discharge lamp, electrodeless lamp, or the like. In this regard, the optical illumination source 324 can provide an optical illumination beam 326 with low coherence (e.g., low spatial coherence and / or temporal coherence).

[0043] In another embodiment, optical illumination source 324 guides optical illumination beam 326 to sample 316 via illumination path 328. Illumination path 328 may include one or more illumination path lenses 334 or additional optical components 332 adapted to modify and / or adjust optical illumination beam 326. For example, one or more optical components 332 may include (but are not limited to) one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, or one or more beam shapers. Illumination path 328 may further include objective lens 338 configured to guide optical illumination beam 326 to sample 316.

[0044] In another embodiment, sample 316 is placed on sample stage 318. Sample stage 318 may include any means suitable for positioning and / or scanning sample 316 within one or more metrology subsystems 202. For example, sample stage 318 may include any combination of linear translation stage, rotation stage, tilting / tilting stage, or the like.

[0045] In another embodiment, one or more metrology subsystems 202 include one or more detectors 322 configured to capture light emitted from sample 316 via light-collecting path 330. Light-collecting path 330 may include (but is not limited to) one or more light-collecting path lenses 336, 340 for collecting light from sample 316. For example, one or more detectors 322 may receive light reflected or scattered from sample 316 (e.g., via specular reflection, diffuse reflection, and the like) via one or more light-collecting path lenses 336, 340. By another example, one or more detectors 322 may receive light generated by sample 316 (e.g., emission associated with absorption of optical illumination beam 326, or the like). By another example, one or more detectors 322 may receive one or more diffraction orders of light from sample 316 (e.g., 0th order diffraction, ±1st order diffraction, ±2nd order diffraction, and the like).

[0046] It should be noted that one or more detectors 322 may be configured to simultaneously capture light emitted from multiple portions of the sample 316 (e.g., the first set of pattern elements 102, the second set of pattern elements 104, and / or the third set of pattern elements 106). In this way, the metrology system 200 can be configured to reduce the amount of time required to determine the superposition error, because the operation of the metrology system 200 can be performed "in real time" and the operation does not need to be interrupted between each individual superposition measurement.

[0047] One or more detectors 322 may comprise any type of detector known in the art suitable for measuring illumination received from sample 316. For example, detector 322 may comprise (but is not limited to) a CCD detector, a TDI detector, a photomultiplier tube (PMT), an avalanche photodiode (APD), a complementary metal-oxide-semiconductor (CMOS) sensor, or the like. In another embodiment, detector 322 may comprise a spectral detector suitable for identifying the wavelength of light emitted from sample 316.

[0048] In one embodiment, one or more detectors 322 are positioned approximately normal to the surface of sample 316. In another embodiment, one or more metrology subsystems 202 include beam splitters oriented such that objective lens 338 can simultaneously direct optical illumination beam 326 to sample 316 and collect light emitted from sample 316. Furthermore, illumination path 328 and light-collecting path 330 may share one or more additional elements (e.g., objective lens 338, aperture, filter, or the like).

[0049] As previously described, one or more metering subsystems 202 may include a controller 204 communicatively coupled to one or more metering subsystems 202. The controller 204 may be configured to direct one or more metering subsystems 202 to generate a superposition signal based on one or more selected recipes. The controller 204 may be further configured to receive data from one or more metering subsystems 202, including (but not limited to) the superposition signal. Additionally, the controller 204 may be configured to determine a superposition associated with a superposition target based on the acquired superposition signal.

[0050] The controller 204 can be configured to determine the superposition value of sample 316 based on one or more superposition measurements of the sample. For example, the controller 204 can be configured to generate one or more superposition measurements of sample 316 based on one or more signals indicating illumination emitted from one or more portions of sample 316 (e.g., the first set of pattern elements 102, the second set of pattern elements 104, and / or the third set of pattern elements 106). The one or more superposition measurements of sample 316 may correspond to the superposition positions of one or more layers of sample 316.

[0051] One or more superimposed measurements of sample 316 may include one or more measurements of the intensity of illumination emitted from the first set of pattern elements 102, the second set of pattern elements 104, and / or the third set of pattern elements 106. For example, controller 204 may be configured to determine the intensity of illumination collected by one or more detectors 322 (and / or particle detector 320). By another example, controller 204 may be configured to determine the intensity of illumination emitted from the first set of pattern elements 102 (with pitch P1), the second set of pattern elements 104 (with pitch P2), and / or the third set of pattern elements 106 (with pitch P3) according to Equation 1 as sample 316 moves at a velocity v (e.g., by translation of stage 318).

[0052] Equation 1

[0053]

[0054] It should be noted that the intensity determined by controller 204 using Equation 1 is presented in the context of having a +1 diffraction order. It should be clearly considered that embodiments of this disclosure are not limited to this context, and controller 204 may be configured to determine the intensity of illumination emitted from sample 316 having various diffraction orders (e.g., -1 diffraction order).

[0055] The controller 204 may be configured to further determine the relative variations in the intensity of illumination emitted from various portions of the sample 316 (e.g., the intensity difference between illumination emitted from the first group of pattern elements 102 and the second group of pattern elements 104 and / or the third group of pattern elements 106). For example, the controller 204 may determine the intensity variations between illumination emitted from the first group of pattern elements 102 and the second group of pattern elements 104 and / or the third group of pattern elements 106 according to Equation 2.

[0056] Equation 2

[0057]

[0058] It should be noted that the intensity determined by controller 204 using Equation 2 is presented in the context of illumination having a +1 diffraction order. It should be clearly considered that embodiments of this disclosure are not limited to this context, and controller 204 may be configured to determine the intensity of illumination emanating from sample 316 having various diffraction orders (e.g., -1 diffraction order).

[0059] The controller 204 can further be configured to determine the phase difference with respect to the illumination emitted from the first set of pattern elements 102, the second set of pattern elements 104, and / or the third set of pattern elements 106. For example, the controller 204 can determine the phase difference between the illumination emitted from the first set of pattern elements 102 and the second set of pattern elements 104 according to Equation 3 (this phase difference is determined by σ). 12 (represented by) the phase difference between the illumination emitted from the second group of pattern elements 104 and the third group of pattern elements 106 (this phase difference is represented by б). 23 (represented) and / or the phase difference between the illumination emitted from the first group of pattern elements 102 and the third group of pattern elements 106 (this phase difference is represented by б) 13 express).

[0060] Equation 3

[0061]

[0062]

[0063]

[0064] Controller 204 may be further configured to determine the superposition value (e.g., superposition error) between the two layers of sample 316 based on the phase difference calculated according to Equation 3. For example, controller 204 may be configured to determine the superposition error (e.g., OVL) between the first layer and the second layer of sample 316 according to Equation 4. 1-2 ).

[0065] Equation 4

[0066]

[0067] One or more processors 206 of controller 204 may comprise any processor or processing element known in the art. For the purposes of this disclosure, the terms “processor” or “processing element” may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application-specific integrated circuit (ASIC) devices, one or more field-programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, one or more processors 206 may comprise any device configured to execute algorithms and / or instructions (e.g., program instructions stored in memory). In one embodiment, one or more processors 206 may embody a desktop computer, host computer system, workstation, graphics computer, parallel processor, networked computer, or any other computer system configured to execute a program (which is configured to operate or in conjunction with metering system 200), as described throughout this disclosure. Furthermore, the steps described throughout this disclosure may be performed by a single controller 204 or alternatively by multiple controllers. Additionally, controller 204 may comprise one or more controllers housed in a common enclosure or within multiple enclosures. In this way, any controller or combination of controllers can be individually packaged as a module suitable for integration into the metering system 200. Furthermore, the controller 204 can analyze data received from one or more metering subsystems 202 and feed the data to additional components within or outside the metering system 200.

[0068] Memory media 208 may comprise any storage medium known in the art suitable for storing program instructions executable by one or more associated processors 206. For example, memory media 208 may comprise a non-transitory memory medium. By another example, memory media 208 may comprise (but is not limited to) read-only memory (ROM), random access memory (RAM), magnetic or optical storage devices (e.g., magnetic disks), magnetic tape, solid-state drives, and the like. It should further be noted that memory media 208 may be housed together with one or more processors 206 within a common controller housing. In one embodiment, memory media 208 may be remotely located relative to the physical location of one or more processors 206 and controller 204. For example, one or more processors 206 of controller 204 may access remote storage (e.g., a server) accessible via a network (e.g., the Internet, an intranet, and the like).

[0069] In one embodiment, a user interface (not shown) is communicatively coupled to controller 204. The user interface may include (but is not limited to) one or more desktop computers, laptop computers, tablet computers, and the like. In another embodiment, the user interface includes a display for displaying data from the metering system 200 to a user. The display of the user interface may include any display known in the art. For example, the display may include (but is not limited to) a liquid crystal display (LCD), an organic light-emitting diode (OLED) based display, or a CRT display. Those skilled in the art will recognize that any display device capable of being integrated with the user interface is suitable for the embodiments described in this disclosure. In another embodiment, a user may input selections and / or commands via a user input device of the user interface in response to data displayed to the user.

[0070] In another embodiment, controller 204 is communicatively coupled to one or more elements of metering system 200. In this respect, controller 204 may transmit data and / or receive data from any component of metering system 200. For example, controller 204 may be communicatively coupled to detectors 320, 322 to receive one or more images from detectors 320, 322. Furthermore, controller 204 may direct or otherwise control any component of metering system 200 by generating one or more control signals for associated components.

[0071] Figure 4 A flowchart illustrating the steps of a method 400 for superimposing measurement samples according to one or more embodiments of the present disclosure.

[0072] In step 402, the illumination includes samples of one or more metrological targets 100. For example, the metrological system 200 may direct an illumination beam onto sample 316. As used herein, the term "illumination beam" may refer to any beam of radiation, including (but not limited to) optical illumination beam 326.

[0073] In step 404, illumination emitted from the first set of pattern elements 102, the second set of pattern elements 104, and the third set of pattern elements 106 of the measurement target 100 is detected. For example, an optical illumination beam 326 may be detected.

[0074] In step 406, one or more first superposition measurements are generated. For example, controller 204 may be configured to generate one or more first superposition measurements of sample 316 based on one or more signals indicating illumination emitted from one or more portions of the first set of pattern elements 102. The one or more first superposition measurements of sample 316 may include one or more intensity measurements (e.g., controller 204 may determine one or more intensity and / or phase differences according to Equations 1 to 3).

[0075] In step 408, one or more second superimposed measurements are generated. For example, controller 204 may be configured to generate one or more second superimposed measurements of sample 316 based on one or more signals indicating illumination emitted from one or more portions of the second set of pattern elements 104. The one or more second superimposed measurements of sample 316 may include one or more intensity measurements (e.g., controller 204 may determine one or more intensity and / or phase differences according to Equations 1 to 3).

[0076] In step 410, one or more third superimposed measurements are generated. For example, controller 204 may be configured to generate one or more third superimposed measurements of sample 316 based on one or more signals indicating illumination emitted from one or more portions of the third set of pattern elements 106. The one or more third superimposed measurements of sample 316 may include one or more intensity measurements (e.g., controller 204 may determine one or more intensity and / or phase differences according to Equations 1 to 3).

[0077] In step 412, the superposition error is determined based on one or more first superposition measurements, one or more second superposition measurements, and / or one or more third superposition measurements. For example, controller 204 may be configured to use Equation 4 to generate the superposition error between the first layer and the second layer of sample 316.

[0078] In some embodiments, method 400 may include one or more additional steps (e.g., optional step 414) wherein one or more superposition correctable amounts are provided based on one or more superposition values ​​determined in at least step 412. For example, one or more additional steps may include controller 204 generating one or more control signals (or corrections to control signals) for adjusting one or more parameters (e.g., manufacturing settings, configurations, and the like) of one or more process tools (e.g., lithography tools). The control signals (or corrections to control signals) may be provided by controller 204 as part of a feedback and / or feedforward control loop. Controller 204 may cause one or more process tools to perform one or more adjustments to one or more parameters of one or more process tools based on one or more control signals (or corrections to control signals). In some embodiments, controller 204 may alert a user to make one or more adjustments. In this sense, one or more control signals may compensate for errors in one or more manufacturing processes of one or more process tools, and thus enable one or more process tools to maintain superposition within selected tolerances across multiple exposures on subsequent samples in the same or different batches.

[0079] Figure 5 The process flow diagram described below illustrates the steps of a method 500 for forming a metering target 100, according to one or more embodiments of the present disclosure.

[0080] In step 502, a first set of pattern elements 102 is formed within the first unit 101 and the second unit 103 of the sample. For example, a first portion of the first set of pattern elements 102 may be formed within the first unit 101, and a second portion of the first set of pattern elements 102 may be formed within the second unit 103. The first set of pattern elements 102 may be manufactured through one or more process steps (e.g., but not limited to one or more deposition, photolithography, or etching steps). The first set of pattern elements 102 may be formed using one or more process tools (e.g., photolithography tools).

[0081] In step 504, a second set of pattern elements 104 is formed within the first unit 101 and the second unit 103 of the sample. For example, a first portion of the second set of pattern elements 104 may be formed within the first unit 101, and a second portion of the second set of pattern elements 104 may be formed within the second unit 103. The second set of pattern elements 104 may be fabricated through one or more process steps (e.g., but not limited to one or more deposition, photolithography, or etching steps). The second set of pattern elements 104 may be formed using one or more process tools (e.g., photolithography tools).

[0082] In step 506, a third set of pattern elements 106 is formed within the first unit 101 and the second unit 103 of the sample. For example, a first portion of the third set of pattern elements 106 may be formed within the first unit 101, and a second portion of the third set of pattern elements 106 may be formed within the second unit 103. The third set of pattern elements 106 may be fabricated through one or more process steps (e.g., but not limited to one or more deposition, photolithography, or etching steps). The third set of pattern elements 106 may be formed using one or more process tools (e.g., photolithography tools).

[0083] All methods described herein may include storing the results of one or more steps of the method embodiments in memory. The results may include any results described herein and may be stored in any manner known in the art. The memory may include any memory described herein or any other suitable storage medium known in the art. After the results have been stored, they may be accessed in memory and used by any method or system embodiment described herein, formatted for display to a user, used by another software module, method, or system, etc. Furthermore, the results may be stored "permanently," "semi-permanently," "temporarily," or for a period of time. For example, the memory may be random access memory (RAM), and the results may not need to be stored in memory indefinitely.

[0084] Upon further careful consideration, each of the embodiments of the methods described above may include any other steps of any other method described herein. Furthermore, each of the embodiments of the methods described above can be executed by any system described herein.

[0085] Those skilled in the art will recognize that, for clarity of concept, the components, operations, devices, objects, and accompanying discussions described herein are used as examples, with careful consideration given to various configuration modifications. Therefore, as used herein, the specific examples illustrated and the accompanying discussions are intended to represent their more general categories. In general, the use of any specific example is intended to represent its category, and the omission of specific components, operations, devices, and objects should not be considered limiting.

[0086] As used herein, directional terms such as “top,” “bottom,” “above,” “below,” “up,” “down,” “down,” and “towards” are intended to provide relative positions for descriptive purposes and are not intended to specify an absolute frame of reference. Those skilled in the art will appreciate various modifications to the described embodiments, and the general principles defined herein may be applied to other embodiments.

[0087] Regarding the use of any plural and / or singular terms in this document, those skilled in the art can convert plural to singular and / or singular to plural depending on the context and / or application. For clarity, various singular / plural arrangements are not explicitly described herein.

[0088] The objects described herein sometimes refer to different components contained within or connected to other components. It should be understood that such depicted architectures are merely exemplary, and many other architectures can in fact be implemented to achieve the same functionality. Conceptually, any arrangement of components used to achieve the same functionality is effectively “associated” to achieve the desired functionality. Therefore, any two components combined herein to achieve a particular functionality can be considered “associated” with each other to achieve the desired functionality, regardless of the architecture or intermediate components. Similarly, any two such associated components can also be considered “connected” or “coupled” to each other to achieve the desired functionality, and any two components that can be suchly associated can also be considered “coupleable” to each other to achieve the desired functionality. Specific examples of coupleability include (but are not limited to) physically mating and / or physically interacting components and / or wirelessly interacting and / or logically interacting components.

[0089] Furthermore, it should be understood that the invention is defined by the appended claims. Those skilled in the art will understand that, generally, the terminology used herein and particularly in the appended claims (e.g., the body of the appended claims) is intended to be “open-ended” (e.g., the term “comprising” should be interpreted as “including (but not limited to)”, the term “having” should be interpreted as “at least having”, the term “includes” should be interpreted as “including (but not limited to)”, and the like). Those skilled in the art will further understand that if a particular number is intended to be introduced by the claims, then this intention will be explicitly stated in the claims, and in the absence of such a statement, this intention will not exist. For example, as an aid to understanding, the appended claims may contain the introductory phrases “at least one” and “one or more” to introduce the claims. However, the use of such phrases should not be interpreted as implying that introducing a claim statement with the indefinite article "a (a / an)" limits any particular claim containing this introduced claim statement to an invention containing only one of such statements, even if the same claim contains the introductory phrase "a or more" or "at least one" and an indefinite article such as "a (a / an)" (e.g., "a (a and / or an)" should generally be interpreted as meaning "at least one" or "a or more"); the same applies to the use of definite articles used to introduce a claim statement. Furthermore, even if a specific number of statements is explicitly stated in the introduced claim statement, those skilled in the art will recognize that such a statement should generally be interpreted as meaning at least the number stated (e.g., the basic statement of "two statements" (without other modifiers) generally means at least two statements or two or more statements). Furthermore, in examples where conventional expressions such as "at least one of A, B, and C and similar ones" are used, a person skilled in the art will generally understand the meaning of such conventional expressions and anticipate this construction (e.g., "a system having at least one of A, B, and C" would include (but is not limited to) systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). In examples where conventional expressions such as "at least one of A, B, or C and similar ones" are used, a person skilled in the art will generally understand the meaning of such conventional expressions and anticipate this construction (e.g., "a system having at least one of A, B, or C" would include (but is not limited to) systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). Those skilled in the art will further understand that any conjunction and / or phrase presenting two or more alternatives, whether in the description, claims or drawings, should be understood to imply the possibility of including one, any, or both of the items.For example, the phrase “A or B” will be understood as containing the possibility of “A” or “B” or “A and B”.

[0090] It will be understood from the foregoing description that this disclosure and its many accompanying advantages will be clear, and that various changes can be made to the form, construction, and arrangement of the components without departing from the subject matter of the disclosure or sacrificing all its material advantages. The forms described are merely illustrative, and the following claims are intended to cover and encompass such changes. Furthermore, it should be understood that the invention is defined by the appended claims.

Claims

1. A measurement target comprising a first unit, wherein the first unit comprises: A first portion of a first set of pattern elements is formed in a first sample layer along a first measurement direction, wherein the first set of pattern elements includes segmented pattern elements having a first pitch; The first part of the second set of pattern elements is formed in the second sample layer along the first measurement direction, wherein the second set of pattern elements includes segmented pattern elements with a second pitch; and The first part of the third group of pattern elements is formed in the first sample layer along the first measurement direction, wherein the third group of pattern elements includes segmented pattern elements with a third pitch. Wherein, when the sample moves at a certain speed, at least one of the intensity or phase variation of the diffraction order of the illumination beam incident by the first part of the first group of pattern elements, the first part of the second group of pattern elements, and the first part of the third group of pattern elements is determined, and the at least one of the intensity or phase variation is related to the superposition between the first sample layer and the second sample layer along the first measurement direction.

2. The measurement target according to claim 1, further comprising a second unit, wherein the second unit comprises: The second portion of the first group of pattern elements, wherein the second portion of the first group of pattern elements is formed along a second measurement direction; The second portion of the second set of pattern elements, wherein the second portion of the second set of pattern elements is formed along the second measurement direction; and The second portion of the third group of pattern elements, wherein the second portion of the third group of pattern elements is formed along the second measurement direction.

3. The metrological target according to claim 2, wherein the metrological target is compatible with the scattering superposition (SCOL) metrological mode.

4. The measurement target according to claim 3, wherein the measurement target is compatible with one or more real-time measurement modes.

5. The measurement target according to claim 1, wherein the sample comprises a semiconductor wafer.

6. The metrological target of claim 1, wherein at least one of the intensity or phase variation of the diffraction order of the illumination beam incident from the first portion of the first set of pattern elements, the first portion of the second set of pattern elements, and the first portion of the third set of pattern elements comprises: At least one of the +1 diffraction order or the -1 diffraction order.

7. A system comprising: One or more controllers having one or more processors communicatively coupled to one or more metering subsystems, wherein the one or more processors are configured to execute a set of program instructions maintained in memory, wherein the set of program instructions are configured to cause the one or more processors to: The system receives one or more signals from the one or more metrology subsystems indicating illumination emitted from a first set of pattern elements, a second set of pattern elements, and a third set of pattern elements from one or more metrology targets of the sample, wherein the one or more metrology targets of the sample include: a first unit comprising a first portion of a first set of pattern elements formed along a first measurement direction on a first sample layer, wherein the first set of pattern elements includes segmented pattern elements having a first pitch; a first portion of a second set of pattern elements formed along the first measurement direction on a second sample layer, wherein the second set of pattern elements includes segmented pattern elements having a second pitch; and a first portion of a third set of pattern elements formed along the first measurement direction on the first sample layer, wherein the third set of pattern elements includes segmented pattern elements having a third pitch. The first overlay measurement is obtained based on the first set of pattern elements; The second superposition measurement is obtained based on the second set of pattern elements; A third overlay measurement is obtained based on the third set of pattern elements; and The superposition error is determined based on at least two of the first superposition measurement, the second superposition measurement, or the third superposition measurement obtained when the sample moves at a certain speed.

8. The system of claim 7, wherein the one or more measurement targets of the sample further include a second unit, wherein the second unit comprises: The second portion of the first group of pattern elements, wherein the second portion of the first group of pattern elements is formed along a second measurement direction; The second portion of the second set of pattern elements, wherein the second portion of the second set of pattern elements is formed along the second measurement direction; and The second portion of the third group of pattern elements, wherein the second portion of the third group of pattern elements is formed along the second measurement direction.

9. The system according to claim 7, wherein the one or more metering subsystems comprise: Lighting source; One or more lighting elements configured to direct a beam of illumination from the lighting source onto the sample; One or more detectors; and One or more projection elements configured to collect illumination emitted from the sample and direct the illumination to the one or more detectors.

10. The system of claim 9, wherein the one or more metrology subsystems include one or more scattering-based superposition (SCOL) metrology subsystems.

11. The system of claim 9, wherein the first superimposed measurement, the second superimposed measurement, and the third superimposed measurement are acquired in real time.

12. The system of claim 7, wherein the sample comprises a semiconductor wafer.

13. The system of claim 7, wherein when the sample moves at a certain speed, at least one of the intensity or phase variation of the diffraction order of the illumination beam incident by the first portion of the first set of pattern elements, the first portion of the second set of pattern elements, and the first portion of the third set of pattern elements is determined, the at least one of the intensity or phase variation being related to the superposition between the first sample layer and the second sample layer along the first measurement direction, and the at least one of the intensity or phase variation of the diffraction order of the illumination beam incident by the first portion of the first set of pattern elements, the first portion of the second set of pattern elements, and the first portion of the third set of pattern elements comprises: At least one of the +1 diffraction order or the -1 diffraction order.

14. A method for measuring superposition, comprising: The lighting has a sample with one or more measurement targets; The detection indicates one or more illumination signals emitted from a first set of pattern elements, a second set of pattern elements, and a third set of pattern elements of one or more measurement targets of the sample, wherein the one or more measurement targets of the sample include: a first unit comprising a first portion of a first set of pattern elements formed along a first measurement direction in a first sample layer, wherein the first set of pattern elements includes segmented pattern elements having a first pitch; a first portion of a second set of pattern elements formed along the first measurement direction in a second sample layer, wherein the second set of pattern elements includes segmented pattern elements having a second pitch; and a first portion of a third set of pattern elements formed along the first measurement direction in the first sample layer, wherein the third set of pattern elements includes segmented pattern elements having a third pitch. A first superposition measurement is obtained based on one or more signals indicating illumination emitted from the first set of pattern elements; A second superposition measurement is obtained based on one or more signals indicating illumination emitted from the second set of pattern elements; A third superposition measurement is obtained based on one or more signals indicating illumination emitted from the third set of pattern elements; and The superposition error is determined based on at least one of the first superposition measurement, the second superposition measurement, or the third superposition measurement obtained when the sample moves at a certain speed.

15. The method of claim 14, wherein the one or more measurement targets of the sample further include a second unit, wherein the second unit comprises: The second portion of the first group of pattern elements, wherein the second portion of the first group of pattern elements is formed along a second measurement direction; The second portion of the second set of pattern elements, wherein the second portion of the second set of pattern elements is formed along the second measurement direction; and The second portion of the third group of pattern elements, wherein the second portion of the third group of pattern elements is formed along the second measurement direction.

16. The method of claim 14, wherein the one or more metrological targets are compatible with a scattering-based superposition (SCOL) metrological mode.

17. The method of claim 14, wherein the first superimposed measurement, the second superimposed measurement, and the third superimposed measurement are acquired in real time.

18. The method of claim 14, wherein the sample comprises a semiconductor wafer.

19. The method of claim 14, wherein determining at least one of the intensity or phase variation of the diffraction order of an illumination beam incident on the first portion of the first set of pattern elements, the first portion of the second set of pattern elements, and the first portion of the third set of pattern elements while the sample moves at a certain speed, the at least one of the intensity or phase variation being related to the superposition between the first sample layer and the second sample layer along the first measurement direction, and the at least one of the intensity or phase variation of the diffraction order of the illumination beam incident on the first portion of the first set of pattern elements, the first portion of the second set of pattern elements, and the first portion of the third set of pattern elements comprises: At least one of the +1 diffraction order or the -1 diffraction order.

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