Measurement target for one-dimensional measurement of periodic displacement

Abstract

To provide a metrology target that is compatible with one-dimensional metrology methods, where the metrology target may occupy a smaller area of ​​the overlay metrology sample. The metrology target (100) includes a first target structure set having one or more first target structures (102a, 102b) formed within at least one of a first work zone (106) or a second work zone (108) of a specimen. The metrology target includes a second target structure set having one or more second target structures (104a, 104b) formed within at least one of the first work zone (106) or the second work zone. The first work zone may include a center of symmetry that overlaps with the center of symmetry of the second work zone when there is no overlay error of one or more layers of the specimen. The metrology target may further include a third target structure set, a fourth target structure set, and a fifth target structure set.

Description

[Technical Field]

[0001] The present disclosure relates generally to overlay metrology, and more particularly to overlay metrology using metrology targets for one-dimensional measurement of periodic misalignment. [Background technology]

[0002] REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 034,414 (filed June 4, 2020, ADVANCED DESIGN OF ONE-DIMENSIONAL PERIODIC MISREGISTRATION MEASUREMENT MARKS), Yoel Feler and Mark Ghinovker, which is incorporated herein by reference in its entirety.

[0003] Overlay metrology targets are typically designed to provide diagnostic information regarding the alignment of multiple layers of a sample by characterizing the overlay target with target features located on the sample layer of interest. Furthermore, the overlay alignment of multiple layers is typically determined by aggregating overlay measurements of multiple overlay targets at various locations across the sample. However, the accuracy of the overlay metrology of an overlay metrology target can be sensitive to specific locations on the sample. In this regard, as the size of overlay metrology samples continues to decrease, it becomes necessary to use overlay metrology targets configured to fit on and / or within the overlay metrology sample. Current methods of overlay metrology often involve measurements along two measurement directions (e.g., two-dimensional measurements). However, two-dimensional measurements often require larger-sized metrology targets. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2011 / 0058170 Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore desirable to provide a metrology target that is compatible with one-dimensional metrology methods, where the metrology target may occupy a smaller area of ​​the overlay metrology specimen. [Means for solving the problem]

[0006] A metrology target according to one or more embodiments of the present disclosure is disclosed. In one embodiment, the metrology target includes a first set of target structures formed on one or more layers of a specimen, the first set of target structures including at least one first target structure formed in at least one of a first work zone of the metrology target or a second work zone of the metrology target. Each first target structure includes one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction. A second set of target structures formed on one or more layers of the specimen, the second set of target structures including at least one second target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target, each second target structure including one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction. When there is no overlay error between one or more layers of the specimen, the center of symmetry of the first work zone of the metrology target and the center of symmetry of the second work zone of the metrology target overlap, and a difference in the overlap between the center of symmetry of the first work zone and the center of symmetry of the second work zone indicates one or more overlay errors between the layers of the metrology target along at least one of the first measurement direction or the second measurement direction.

[0007] A system according to one or more embodiments of the present disclosure is disclosed. In one embodiment, the system includes a controller communicatively coupleable to one or more metrology subsystems, the controller including one or more processors, the one or more processors configured to execute a set of program instructions maintained in a memory, the set of program instructions configured to cause the one or more processors to perform the following steps: receiving, from the one or more metrology subsystems, one or more signals indicative of illumination emanating from a measurement target of the specimen, the measurement target of the specimen comprising a first set of target structures formed on one or more layers of the specimen, the first target structure set including at least one first target structure formed in at least one of a first working zone of the metrology target or a second working zone of the metrology target, each first target structure including one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction; a second target structure set formed on one or more layers of the specimen, the second target structure set including at least one second target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target, each second target structure including one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, wherein when there is no overlay error between one or more layers of the specimen, a center of symmetry of the first work zone of the metrology target and a center of symmetry of the second work zone of the metrology target overlap, and a difference in overlap between the centers of symmetry of the first work zone and the second work zone indicates one or more overlay errors between the layers of the metrology target along at least one of the first measurement direction or the second measurement direction; and generating at least first overlay measurements based on one or more signals indicative of illumination emanating from one or more portions of the first target structure set.generating at least second overlay measurements based on one or more signals indicative of illumination emanating from one or more portions of the second set of target structures; and determining an overlay error of the specimen based on the first overlay measurement and the second overlay measurement.

[0008] In accordance with one or more embodiments of the present disclosure, a method for measuring overlay of a specimen is disclosed. The method for measuring overlay of a specimen may include irradiating a specimen having a metrology target, the metrology target comprising: a first set of target structures formed on one or more layers of the specimen, the first set of target structures including at least one first target structure formed in at least one of a first work zone of the metrology target or a second work zone of the metrology target, each first target structure including one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction; and a second set of target structures formed on one or more layers of the specimen, the second set of target structures including at least one second target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target, each second target structure including one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction. The method comprises the steps of: detecting illumination emanating from a measurement target of the specimen; generating at least a first overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the first set of target structures; generating at least a second overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the second set of target structures; and determining an overlay error of the specimen based on the first overlay measurement and the second overlay measurement; wherein when there is no overlay error between one or more layers of the specimen, the center of symmetry of a first working zone of the measurement target and the center of symmetry of a second working zone of the measurement target overlap; and a difference in the overlap between the center of symmetry of the first working zone and the center of symmetry of the second working zone indicates one or more overlay errors between layers of the measurement target along at least one of a first measurement direction or a second measurement direction.

[0009] According to one or more embodiments of the present disclosure, a method of forming a metrology target is disclosed. The method of forming the metrology target includes forming a first set of target structures on one or more layers of a specimen, the first set of target structures including at least one first target structure formed in at least one of a first work zone of the metrology target or a second work zone of the metrology target, each first target structure including one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction, and forming a second set of target structures on the one or more layers of the specimen, the second set of target structures including at least one second target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target, each second target structure including one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction. When there is no overlay error between the one or more layers of the specimen, a center of symmetry of the first work zone of the metrology target and a center of symmetry of the second work zone of the metrology target overlap. Additionally, a difference in the overlap between the center of symmetry of the first work zone and the center of symmetry of the second work zone indicates one or more overlay errors between the layers of the metrology target along at least one of the first measurement direction or the second measurement direction.

[0010] The many advantages of the present disclosure may be better understood by those skilled in the art by reference to the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1B] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1C] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1D]FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1E] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1F] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 1G] FIG. 1 is a top view of a metrology target in accordance with one or more embodiments of the present disclosure. [Figure 2] FIG. 1 is a conceptual diagram of a metrology system in accordance with one or more embodiments of the present disclosure. [Figure 3A] FIG. 1 illustrates a conceptual diagram of a metrology subsystem in accordance with one or more embodiments of the present disclosure. [Figure 3B] FIG. 1 illustrates a conceptual diagram of a metrology subsystem in accordance with one or more embodiments of the present disclosure. [Figure 4] FIG. 1 is a process flow diagram illustrating steps in a method for measuring overlay on a specimen in accordance with one or more embodiments of the present disclosure. [Figure 5] FIG. 1 is a process flow diagram illustrating steps in a method of forming a metrology target in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Semiconductor devices may be formed as multiple printed layers of patterned material on a substrate. Each printed layer may be processed through a series of process steps, such as, but not limited to, one or more material deposition steps, one or more lithography steps, or one or more etching steps. In some manufacturing processes, the printed layers may be formed using one or more photoresist materials. For example, a photoresist material may be deposited on a substrate. The photoresist material may then be exposed to illumination, which generates a latent target pattern in the photoresist material. The latent target pattern (or a developed target pattern formed from the latent target pattern) may then be used as a pattern for one or more lithography 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 generate a latent target pattern in 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.

[0013] During manufacturing, each printing layer must typically be fabricated within selected tolerances to properly construct the final device. For example, the relative placement of printing elements in each layer (e.g., overlay or overlay parameters) must be well characterized and controlled relative to previously fabricated layers. Accordingly, metrology targets can be fabricated on one or more printing layers to enable efficient characterization of the layer's overlay. Thus, deviations in overlay target features on a printing layer can represent deviations in the printing characteristics of printing device features on that layer. Furthermore, overlay measured in one manufacturing step (e.g., after fabrication of one or more sample layers) can be used to generate correctives for precisely aligning process tools (e.g., lithography tools) for fabrication of additional sample layers in subsequent manufacturing steps.

[0014] Metrology targets typically include well-defined printed elements designed to provide an accurate representation of one or more printing characteristics. In this regard, measured characteristics of the printed elements of a metrology target (e.g., by a metrology tool) can represent the printing device elements associated with the device being fabricated. Furthermore, metrology targets are typically characterized as having one or more measurement cells, each containing a printed element in one or more layers on the sample. Metrology measurements can then be based on any combination of measurements of the size, orientation, or position (e.g., pattern placement) of the printed elements within a single cell or between multiple cells. For example, one or more cells of an overlay metrology target can include printed elements on two or more sample layers arranged such that the relative position of the elements in each layer can indicate an offset error in a particular layer (e.g., pattern placement error (PPE)) or an overlay error associated with alignment errors between sample layers. As another example, a process-sensitive metrology target may include printed elements on a single sample layer, where one or more characteristics of the printed elements (e.g., width or critical dimension (CD), sidewall angle, position, etc.) are indicative of one or more process metrics, including, but not limited to, the dose of illumination during a lithography step or the focal position of the sample within a lithography tool during a lithography step.

[0015] Overlay metrology is typically performed by fabricating one or more overlay targets across a specimen, each overlay target containing features in a specimen layer of interest that are fabricated simultaneously with features associated with the fabricated device or component. In this regard, overlay errors measured at the locations of the overlay targets may represent overlay errors of device features. Overlay metrology may therefore be used to monitor and / or control any number of manufacturing tools to maintain the fabrication of devices according to specified tolerances. For example, overlay measurements of a current layer relative to a previous layer on a specimen may be utilized as feedback data to monitor and / or mitigate deviations in the fabrication of the current layer on additional specimens within a lot. As another example, overlay measurements of a current layer relative to a previous layer on one specimen may be utilized as feedforward data for fabricating subsequent layers on the same specimen, taking into account the existing layer alignment.

[0016] Overlay targets typically contain features specifically designed to be sensitive to overlay errors between sample layers of interest. Overlay metrology may be performed by characterizing the overlay target with an overlay metrology tool and applying an algorithm that determines the overlay error on the sample based on the output of the metrology tool.

[0017] Regardless of the overlay measurement technique, an overlay metrology tool is typically configurable according to a recipe that includes a set of measurement parameters utilized to generate an overlay signal. For example, an overlay metrology tool recipe may include, but is not limited to, illumination wavelength, detection wavelength of radiation emanating from the sample, illumination spot size on the sample, angle of incident illumination, polarization of incident illumination, position of the incident illumination beam on the overlay target, position of the overlay target in the focal volume of the overlay metrology tool, etc. Thus, an overlay recipe may include a set of measurement parameters for generating an overlay signal suitable for determining the overlay of two or more sample layers.

[0018] Overlay metrology tools may utilize various techniques to determine overlay of sample layers. For example, an image-based overlay metrology tool may illuminate an overlay target (e.g., an advanced imaging metrology (AIM) target, a box-in-box metrology target, etc.) and capture an overlay signal including images of overlay target features located on different sample layers. Thus, overlay may be determined by measuring the relative positions of the overlay target features. As another example, a scatterometry-based overlay metrology tool may illuminate an overlay target (e.g., a grating-over-grating metrology target, etc.) and capture an overlay signal including the angular distribution of radiation emitted from the overlay target associated with the diffraction, scattering, and / or reflection of the illumination beam. Thus, overlay may be determined based on a model of the interaction of the illumination beam with the overlay target.

[0019] It is recognized herein that a variety of overlay metrology tools can be used to measure overlay. For example, optical metrology tools (e.g., light-based metrology tools that use electromagnetic radiation for illumination and / or detection) can provide high-throughput overlay measurements using a number 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 scatterometry, in which overlay is determined based on light scattered and / or diffracted from a diffraction grating on multiple layers. For 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, such as, but not limited to, x-ray wavelengths, extreme ultraviolet (EUV) wavelengths, vacuum ultraviolet (VUV) wavelengths, deep ultraviolet (DUV) wavelengths, ultraviolet (UV) wavelengths, visible wavelengths, or infrared (IR) wavelengths. Nos. 8,330,281, 9,476,698, 7,541,201, 2013 / 0035888, 9,214,317, 10,527,951, 10,190,979, and PCT / US2016 / 039531, all of which relate to systems, methods, and apparatus generally related to overlay metrology, are incorporated herein by reference in their entirety.

[0020] As used throughout this disclosure, the term "specimen" generally refers to a substrate formed from a semiconductor or non-semiconductor material (e.g., a wafer, etc.). For example, semiconductor or non-semiconductor materials may include, but are not limited to, monocrystalline silicon, gallium arsenide, and indium phosphide. A specimen may include one or more layers. For example, such layers may include, but are not limited to, resist (including photoresist), dielectric materials, conductive materials, and semiconductor materials. Many different types of such layers are known in the art, and the term specimen, as used herein, is intended to encompass specimens upon which all types of such layers may be formed. One or more layers formed on a specimen may be patterned or unpatterned. For example, a specimen may include multiple dies, each having repeatable patterned features. The formation and processing of such layers of material may ultimately result in a completed device. Many different types of devices can be formed on a specimen, and the term specimen, as used herein, is intended to encompass specimens upon which any type of device known in the art is fabricated. Furthermore, for purposes of this disclosure, the terms specimen and wafer should be interpreted as interchangeable. Further, for the purposes of this disclosure, the terms patterning device, mask, and reticle should be considered interchangeable.

[0021] 1A is a top view of a metrology target 100 in accordance with one or more embodiments of the present disclosure. The metrology target 100 may include a first target structure set formed on one or more layers of the metrology target 100. The first target structure set may include one or more first target structures 102a and 102b. The one or more first target structures 102a and 102b may be formed in at least one of a first work zone 106 of the metrology target 100 or a second work zone 108 of the metrology target 100. Each of the first work zone 106 and the second work zone 108 may be located in one or more layers of the metrology target 100. The one or more first target structures 102a and 102b may include one or more first pattern elements configured for measurement along at least one of a first measurement direction (e.g., x-direction) or a second measurement direction (e.g., y-direction). The one or more first pattern elements may be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure. For example, the one or more first pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode. In this regard, the one or more first pattern elements may be configured to include periodic and / or segmented structures for metrology using a SCOL-based metrology method (e.g., a grating-over-grating structure, or any structure known in the art to be suitable for diffracting, scattering, and / or reflecting an illumination beam). As another example, the one or more first pattern elements may be compatible with any image-based overlay metrology mode, including, but not limited to, an advanced imaging metrology mode (e.g., AIM, triple advanced imaging metrology (TAIM), robust advanced imaging metrology (rAIM), advanced imaging metrology-in-die (AIMid), box-in-box metrology), or any other metrology mode known in the art to be suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers).It should be noted that the one or more first pattern elements may include any one-dimensional or two-dimensional structure, such as any one-dimensional or two-dimensional periodic structure, formed by any means known in the art, including, but not limited to, one or more lithography steps, one or more direct etching steps, or the like. The first target structure set and / or first target structures 102a and 102b may be formed in any shape, including, but not limited to, a square shape, a circular shape, a diamond shape, or a star shape.

[0022] The metrology target 100 may include a second target structure set formed on one or more layers of the metrology target 100. The second target structure set may include one or more second target structures 104a and 104b. The one or more first second structures 104a and 104b may be formed in at least one of the first work zone 106 of the metrology target 100 or the second work zone 108 of the metrology target 100. The one or more second target structures 104a and 104b may include one or more second pattern elements configured for measurement along at least one of a first measurement direction (e.g., x-direction) or a second measurement direction (e.g., y-direction). The one or more second pattern elements may be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure. For example, the one or more second pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode. In this regard, the one or more second pattern elements may be configured to include periodic and / or segmented structures for metrology using SCOL-based metrology methods (e.g., grating-over-grating structures, or any structures known in the art to be suitable for diffracting, scattering, and / or reflecting an illumination beam). As another example, the one or more second pattern elements may be compatible with any image-based overlay metrology mode, including, but not limited to, advanced imaging metrology modes (e.g., AIM, triple advanced imaging metrology (TAIM), robust advanced imaging metrology (rAIM), advanced imaging metrology-in-die (AIMid), box-in-box metrology), or any other metrology mode known in the art to be suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers).It should be noted that the one or more second pattern elements may include any one-dimensional or two-dimensional structure, such as any one-dimensional or two-dimensional periodic structure, formed by any means known in the art, including, but not limited to, one or more lithography steps, one or more direct etching steps, or the like. The second target structure set and / or second target structures 104a and 104b may be formed in any shape, including, but not limited to, a square shape, a circular shape, a diamond shape, or a star shape.

[0023] The first work zone 106 and the second work zone 108 may be formed such that the first work zone 106 and the second work zone 108 can facilitate one or more overlay measurements based on exploiting the rotational symmetry of one or more elements of the first work zone 106 and the second work zone 108. For example, the first work zone 106 may be formed such that the elements of the first work zone 106 (e.g., one or more first target structures 102a and 102b and / or one or more second target structures 104a and 104b) have a center of symmetry, and the second work zone 108 may be formed such that the elements of the second work zone 108 (e.g., one or more first target structures 102a and 102b and / or one or more second target structures 104a and 104b) have a center of symmetry, each of which overlaps at the center of symmetry 110 of the metrology target 100. In this manner, any differences in the overlap of the respective centers of symmetry may be attributable to or indicative of overlay error between layers of metrology target 100. It is contemplated that first work zone 106 and second work zone 108 may have two-fold rotational symmetry, although embodiments of the present disclosure are not limited to first work zone 106 and second work zone 108 having two-fold rotational symmetry. For example, first work zone 106 and second work zone 108 may have four-fold rotational symmetry. It should be noted that the rotational symmetry of first work zone 106 and second work zone 108 may mitigate issues arising in connection with one or more metrology subsystems, including, but not limited to, wafer angle misplacement errors, which may arise during measurement.

[0024] In some embodiments, the first work zone 106 may be formed adjacent to the second work zone 108 (e.g., adjacent along the x-direction, as shown in FIG. 1A). In other embodiments, the first work zone 106 may be formed adjacent to the second work zone 108 along the y-direction, as shown in FIG. 1B. It should be noted that the relative positions of the first work zone 106 and the second work zone 108 may be selected to suit design size or metrology operation requirements. For example, the metrology target 100 may be configured to occupy less space on the metrology specimen based on the relative placement of the first work zone 106 and the second work zone 108.

[0025] It should be noted that one or more portions of any of the target structure sets (e.g., the first target structure set and / or the second target structure set) or any of the target structures (e.g., first target structures 102a and 102b and / or second target structures 104a and 104b) may be formed on different layers of the metrology target or within each of the first and second work zones 106, 108. For example, as shown in Figures 1C and 1D, a first portion of the second target structure 104 may be formed within the first work zone 106 and a second portion of the second target structure 104 may be formed within the second work zone 108.

[0026] It is further noted that embodiments of the present disclosure are not limited to the first work zone 106 and the second work zone 108 occupying a single region of the metrology target 100. For example, each of the first work zone 106 and the second work zone 108 may be formed in multiple areas on the metrology target 100.

[0027] In another embodiment, as shown in FIG. 1E , the metrology target 100 can include a third target structure set formed on one or more layers of the metrology target 100. The third target structure set can include one or more third target structures 112a and 112b. The one or more third second structures 112a and 112b can be formed in at least one of the first work zone 106 of the metrology target 100 or the second work zone 108 of the metrology target 100. The one or more third target structures 112a and 112b can include one or more third pattern elements configured for measurement along at least one of a first measurement direction (e.g., x-direction) or a second measurement direction (e.g., y-direction). The one or more third pattern elements can be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure. For example, the one or more third pattern elements can be compatible with a scatterometry-based overlay (SCOL) metrology mode. In this regard, the one or more third pattern elements may be configured to include periodic and / or segmented structures for metrology using SCOL-based metrology methods (e.g., grating-over-grating structures, or any structure known in the art to be suitable for diffracting, scattering, and / or reflecting an illumination beam). As another example, the one or more third pattern elements may be compatible with any image-based overlay metrology mode, including, but not limited to, advanced imaging metrology modes (e.g., AIM, triple advanced imaging metrology (TAIM), robust advanced imaging metrology (rAIM), advanced imaging metrology-in-die (AIMid), box-in-box metrology), or any other metrology mode known in the art to be suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers).It should be noted that the one or more third pattern elements may include any one-dimensional or two-dimensional structure, such as any one-dimensional or two-dimensional periodic structure, formed by any means known in the art, including, but not limited to, one or more lithography steps, one or more direct etching steps, or the like. The third target structure set and / or third target structures 112a and 112b may be formed in any shape, including, but not limited to, a square shape, a circular shape, a diamond shape, or a star shape.

[0028] In another embodiment, as shown in FIG. 1F , the metrology target 100 can include a fourth target structure set formed on one or more layers of the metrology target 100. The fourth target structure set can include one or more fourth target structures 114a and 114b. The one or more fourth second structures 114a and 114b can be formed in at least one of the first work zone 106 of the metrology target 100 or the second work zone 108 of the metrology target 100. The one or more fourth target structures 114a and 114b can include one or more fourth pattern elements configured for measurement along at least one of a first measurement direction (e.g., x-direction) or a second measurement direction (e.g., y-direction). The one or more fourth pattern elements can be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure. For example, the one or more fourth pattern elements can be compatible with a scatterometry-based overlay (SCOL) metrology mode. In this regard, the one or more fourth pattern elements may be configured to include periodic and / or segmented structures for metrology using SCOL-based metrology methods (e.g., grating-over-grating structures, or any structure known in the art to be suitable for diffracting, scattering, and / or reflecting an illumination beam). As another example, the one or more fourth pattern elements may be compatible with any image-based overlay metrology mode, including, but not limited to, advanced imaging metrology modes (e.g., AIM, triple advanced imaging metrology (TAIM), robust advanced imaging metrology (rAIM), advanced imaging metrology-in-die (AIMid), box-in-box metrology), or any other metrology mode known in the art to be suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers).It should be noted that the one or more fourth pattern elements may include any one-dimensional or two-dimensional structure, such as any one-dimensional or two-dimensional periodic structure, formed by any means known in the art, including, but not limited to, one or more lithography steps, one or more direct etching steps, or the like. The fourth target structure set and / or fourth target structures 114a and 114b may be formed in any shape, including, but not limited to, a square shape, a circular shape, a diamond shape, or a star shape.

[0029] In another embodiment, as shown in FIG. 1G, the metrology target 100 may include a fifth target structure set formed on one or more layers of the metrology target 100. The fifth target structure set may include one or more fifth target structures 116a and 116b. The one or more fifth second structures 116a and 116b may be formed in at least one of the first work zone 106 of the metrology target 100 or the second work zone 108 of the metrology target 100. The one or more fifth target structures 116a and 116b may include one or more fifth pattern elements configured for measurement along at least one of a first measurement direction (e.g., x-direction) or a second measurement direction (e.g., y-direction). The one or more fifth pattern elements may be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure. For example, the one or more fifth pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode. In this regard, the one or more fifth pattern elements may be configured to include periodic and / or segmented structures for metrology using SCOL-based metrology methods (e.g., grating-over-grating structures, or any structure known in the art to be suitable for diffracting, scattering, and / or reflecting an illumination beam). As another example, the one or more fifth pattern elements may be compatible with any image-based overlay metrology mode, including, but not limited to, advanced imaging metrology modes (e.g., AIM, triple advanced imaging metrology (TAIM), robust advanced imaging metrology (rAIM), advanced imaging metrology-in-die (AIMid), box-in-box metrology), or any other metrology mode known in the art to be suitable for capturing overlay signals (e.g., images of overlay target features located on different sample layers).It should be noted that the one or more fifth pattern elements may include any one-dimensional or two-dimensional structure, such as any one-dimensional or two-dimensional periodic structure, formed by any means known in the art, including, but not limited to, one or more lithography steps, one or more direct etching steps, etc. The fifth target structure set and / or fifth target structures 116a and 116b may be formed in any shape, including, but not limited to, a square shape, a circular shape, a diamond shape, or a star shape.

[0030] It is noted herein that embodiments of the present disclosure are not limited to first and second work zones 106, 108 having uniform shapes. For example, as shown in FIG. 1G, each of first and second work zones 106, 108 may be any shape, including, but not limited to, any polygonal shape. Furthermore, it should be noted that one or more portions of any of the target structure sets (e.g., the first target structure set, the second target structure set, the third target structure set, the fourth target structure set, and / or the fifth target structure set) or any of the target structures (e.g., the first target structures 102a and 102b, the second target structures 104, 104a and 104b, the third target structures 112a and 112b, the fourth target structures 114a and 114b, and / or the fifth target structures 116a and 116b) may be formed on different layers of the metrology target or within each of the first and second work zones 106 and 108. For example, as shown in FIG. 1G, a first portion of the second target structure 104 may be formed within the first work zone 106, and a second portion of the second target structure 104 may be formed within the second work zone 108.

[0031] 2 shows a simplified block diagram of a metrology system 200 in accordance with one or more embodiments of the present disclosure. One or more metrology subsystems 202 can be configured to operate in either an imaging mode or a non-imaging mode. For example, in an imaging mode, individual overlay target elements can be resolvable within an illumination spot on the sample (e.g., that is part of a bright-field image, a dark-field image, a phase-contrast image, etc.). As another example, one or more metrology subsystems 202 can operate as a scatterometry-based overlay (SCOL) metrology tool, where radiation from the sample is analyzed at a pupil plane to characterize the angular distribution of radiation from the sample (e.g., related to scattering and / or diffraction of the radiation by the sample).

[0032] The one or more metrology subsystems 202 can direct illumination toward the sample and further collect radiation emanating from the sample to generate an overlay signal suitable for determining the overlay of two or more sample layers. The one or more metrology subsystems can include any type of overlay metrology tool known in the art that is suitable for generating an overlay signal suitable for determining the overlay associated with an overlay target on the sample, including, but not limited to, any optical metrology tool (e.g., an Advanced Imaging Metrology (AIM) tool, an Advanced Imaging Metrology-In-Die (AIMid) tool, a Triple Advanced Imaging Metrology (TAIM) tool, a Robust Advanced Imaging Metrology (rAIM) tool, etc.), any particle-based metrology tool (e.g., an electron beam metrology tool), or a scatterometry-based overlay (SCOL) metrology tool. Note that embodiments of the present disclosure are not limited to metrology system 200 having only one metrology subsystem 202, and metrology system 200 can include at least two metrology subsystems. For example, metrology system 200 can include an optical metrology tool and a scatterometry-based overlay (SCOL) metrology tool.

[0033] The one or more metrology subsystems 202 may be configurable to generate the overlay signal based on any number of recipes that define measurement parameters for obtaining an overlay signal suitable for determining the overlay of the overlay target. For example, the recipes for the one or more metrology subsystems 202 may include, but are not limited to, an illumination wavelength, a detected wavelength of radiation emanating from the sample, a spot size of the illumination on the sample, an angle of incident illumination, a polarization of the incident illumination, a wavefront plan of the incident beam, a position of the beam of incident illumination on the overlay target, a position of the overlay target in a focal volume of the overlay metrology tool, etc.

[0034] In another embodiment, the overlay metrology system 200 includes a controller 204 communicatively coupled to one or more metrology subsystems 202. The controller 204 may be configured to instruct the one or more metrology subsystems 202 to generate overlay signals based on one or more selected recipes. The controller 204 may further be configured to receive data including, but not limited to, the overlay signals from the one or more metrology subsystems 202. Furthermore, the controller 204 may be configured to determine an overlay associated with an overlay target based on the acquired overlay signals.

[0035] In another embodiment, the controller 204 includes one or more processors 206. For example, the one or more processors 206 may be configured to execute a set of program instructions maintained in the memory medium 208 or memory. The controller 204 may be configured to determine an overlay error of a specimen having one or more metrology targets 100 based on one or more overlay measurements of the specimen. For example, in one embodiment, the metrology subsystem 202 may direct illumination at the specimen having one or more metrology targets 100. In another embodiment, the metrology subsystem 202 may be configured to further collect radiation emanating from the specimen to generate one or more overlay measurements (or one or more signals indicative of one or more overlay measurements) suitable for determining the overlay of two or more specimen layers. The metrology subsystem 202 may be configurable to generate the overlay signal based on any number of recipes defining measurement parameters for obtaining an overlay signal suitable for determining the overlay of the overlay targets. For example, the recipe for the metrology subsystem 202 may include, but is not limited to, the illumination wavelength, the detection wavelength of the radiation emanating from the sample, the illumination spot size on the sample, the angle of incident illumination, the polarization of the incident illumination, the position of the beam of incident illumination on the overlay target, the position of the overlay target in the focal volume of the overlay metrology tool, etc.

[0036] The controller 204 may be configured to determine an overlay error of a specimen having one or more metrology targets 100 based on one or more overlay measurements of the specimen. For example, the controller 204 may be configured to generate one or more overlay measurements of the specimen based on one or more signals indicative of illumination emanating from one or more portions of the specimen 320 (e.g., the first set of target structures, the second set of target structures, the third set of target structures, the fourth set of target structures, and / or the fifth set of target structures). The one or more overlay measurements of the specimen 320 may correspond to overlay positions of one or more layers of the specimen 320.

[0037] The one or more processors 206 of the controller 204 may include any processor or processing element known in the art. For purposes of this disclosure, the term “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, the one or more processors 206 may include any device configured to execute algorithms and / or instructions (e.g., program instructions stored in memory). In one embodiment, the one or more processors 206 may be embodied as a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, a networked computer, or any other computer system configured to execute programs that operate or are configured to operate with the measurement 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. Furthermore, the controller 204 may include one or more controllers housed within a common housing or multiple housings. In this manner, any controller or combination of controllers can be separately packaged as a module suitable for integration into metrology system 200. Additionally, controller 204 can analyze data received from one or more metrology subsystems 202 and provide the data to additional components within metrology system 200 or external to metrology system 200.

[0038] The memory medium 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, the storage medium 208 may include a non-transitory storage medium. As another example, the storage medium 208 may include, but is not limited to, read-only memory (ROM), random access memory (RAM), magnetic or optical memory devices (e.g., disks), magnetic tape, solid-state drives, etc. Furthermore, it should be noted that the storage medium 208 may be housed within a common controller housing along with the one or more processors 206. In one embodiment, the memory medium 208 may be located remotely relative to the physical locations of the one or more processors 206 and the controller 204. For example, the one or more processors 206 of the controller 204 may access a remote memory (e.g., a server) accessible via a network (e.g., the Internet, an intranet, etc.).

[0039] In one embodiment, a user interface (not shown) is communicatively coupled to the controller 204. The user interface may include, but is not limited to, one or more desktops, laptops, tablets, etc. In another embodiment, the user interface includes a display used to display data from the measurement 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 integration with a user interface is suitable for implementation in the present disclosure. In another embodiment, a user may input selections and / or commands in response to data displayed to the user via a user input device of the user interface.

[0040] In another embodiment, the controller 204 is communicatively coupled to one or more elements of the metrology system 200. In this regard, the controller 204 can send and / or receive data from any component of the metrology system 200. For example, the controller 204 may be communicatively coupled to the detectors 320, 322 to receive one or more images therefrom. Additionally, the controller 204 can direct or otherwise control any component of the metrology system 200 by generating one or more control signals for the associated component.

[0041] 3A, the one or more metrology subsystems 202 may include an optical metrology subsystem 202a, such as a metrology subsystem including an optical metrology tool. The optical metrology subsystem 202a may include any type of optical metrology tool known in the art suitable for generating metrology data for a specimen, including, but not limited to, an optical metrology tool configured to generate and / or detect an optical illumination beam having x-ray, ultraviolet (UV), infrared (IR), or visible light wavelengths. As another example, the one or more metrology subsystems 202a may include an advanced imaging metrology (AIM) tool, an advanced imaging metrology-in-die (AIMid) tool, a triple advanced imaging metrology (TAIM) tool, or a robust advanced imaging metrology (rAIM) tool.

[0042] In one embodiment, the one or more metrology subsystems 202a may include an optical illumination source 302 configured to generate an optical illumination beam 304. The optical illumination beam 304 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.

[0043] The optical illumination source 302 may include any type of illumination source suitable for providing the optical illumination beam 304. In one embodiment, the optical illumination source 302 is a laser source. For example, the optical illumination source 302 may include, 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 regard, the optical illumination source 302 may provide the optical illumination beam 304 with high coherence (e.g., high spatial coherence and / or temporal coherence). In another embodiment, the optical illumination source 302 includes a laser-sustained plasma (LSP) source. For example, the optical illumination source 302 may include, but is not limited to, an LSP lamp, an LSP bulb, or an 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, the optical illumination source 302 includes a lamp source. For example, the optical illumination source 302 may include, but is not limited to, an arc lamp, a discharge lamp, an electrodeless lamp, etc. In this regard, the optical illumination source 302 may provide an optical illumination beam 304 having low coherence (eg, low spatial and / or temporal coherence).

[0044] In another embodiment, the optical illumination source 302 directs the optical illumination beam 304 toward the sample 320 via an illumination path 310. The illumination path 310 may include one or more illumination path lenses 308 or additional optical components 306 suitable for modifying and / or conditioning the optical illumination beam 304. For example, the one or more optical components 306 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. The illumination path 310 may further include an objective lens 316 configured to direct the optical illumination beam 304 toward the sample 320.

[0045] In another embodiment, the sample 320 is positioned on a sample stage 322. The sample stage 322 may include any device suitable for positioning and / or scanning the sample 320 within one or more metrology subsystems 202a. For example, the sample stage 322 may include any combination of a linear translation stage, a rotation stage, a tip / tilt stage, etc.

[0046] In another embodiment, the one or more metrology subsystems 202a include one or more detectors 324 configured to capture light emanating from the sample 320 through a collection path 314. The collection path 314 may include, but is not limited to, one or more collection path lenses 312, 318 for collecting light from the sample 320. For example, the one or more detectors 324 may receive light reflected or scattered (e.g., via specular reflection, diffuse reflection, etc.) from the sample 320 via the one or more collection path lenses 312, 318. As another example, the one or more detectors 324 may receive light generated by the sample 320 (e.g., luminescence associated with absorption of the optical illumination beam 304, etc.). As another example, the one or more detectors 324 may receive one or more diffraction orders of light from the sample 320 (e.g., 0th diffraction order, ±1st diffraction orders, ±2nd diffraction orders, etc.).

[0047] The one or more detectors 324 may include any type of detector known in the art suitable for measuring illumination received from the sample 320. For example, the detector 324 may include, 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, etc. In another embodiment, the detector 324 may include a spectroscopic detector suitable for identifying wavelengths of light emanating from the sample 320.

[0048] In one embodiment, one or more detectors 324 are positioned approximately perpendicular to the surface of the sample 320. In another embodiment, the one or more metrology subsystems 202a include a beam splitter oriented such that the objective lens 316 can simultaneously direct the optical illumination beam 304 onto the sample 320 and collect light emanating from the sample 320. Additionally, the illumination path 310 and the collection path 314 can share one or more additional elements (e.g., the objective lens 316, an aperture, a filter, etc.).

[0049] In one embodiment, as shown in FIG. 3B, the one or more metrology subsystems 202 may include a particle-based metrology subsystem 202b, such as a metrology subsystem that includes an electron beam metrology tool (e.g., an SEM, a CD-SEM, etc.).

[0050] In one embodiment, the one or more metrology subsystems 202b may include a particle source 325 (e.g., an electron beam source, an ion beam source, etc.) for generating a particle beam 326 (e.g., an electron beam, a particle beam, etc.). The particle source 325 may include any particle source known in the art suitable for generating the particle beam 326. For example, the particle source 325 may include, but is not limited to, an electron gun or an ion gun. In another embodiment, the particle source 325 is configured to provide a particle beam having an adjustable energy. For example, the particle source 325 may include, but is not limited to, an electron source configured to provide an acceleration voltage in the range of 0.1 kV to 30 kV. As another example, a particle source 325 including an ion source may provide an ion beam having an energy in the range of 1 keV to 50 keV, although this is not required.

[0051] In another embodiment, the one or more metrology subsystems 202b may include one or more particle focusing elements 328. For example, the one or more particle focusing elements 328 may include, but are not limited to, a single particle focusing element or one or more particle focusing elements forming a combined system. In another embodiment, the one or more particle focusing elements 328 include a particle objective lens 330 configured to direct the particle beam 326 toward the sample 320 located on the sample stage 322. Additionally, the particle source 325 may include any type of electron lens known in the art, including, but not limited to, an electrostatic lens, a magnetic lens, a monopotential lens, or a bipotential lens.

[0052] In another embodiment, one or more metrology subsystems 202b include at least one particle detector 332 to image or detect particles emanating from the sample 320. In one embodiment, the particle detector 332 includes an electron collector (e.g., a secondary electron collector, a backscattered electron detector, etc.). In another embodiment, the particle detector 332 includes a photon detector (e.g., a light detector, an x-ray detector, a scintillator element coupled to a photomultiplier tube (PMT) detector, etc.) for detecting electrons and / or photons from the sample surface. It is specifically contemplated that one or more metrology subsystems 202b may include multiple (e.g., at least two) particle detectors 332. It is noted herein that certain types of particle detectors 332 (e.g., photomultiplier tube detectors) may increase the sensitivity of one or more metrology subsystems 202b.

[0053] It should be understood that the description of the one or more metrology subsystems 202 depicted in Figures 3A-3B, and the related description above, is provided for illustrative purposes only and should not be construed as limiting. For example, the one or more metrology subsystems 202 may include a multi-beam and / or multi-column system suitable for simultaneously interrogating the sample 320. In further embodiments, the one or more metrology subsystems 202 may include one or more components (e.g., one or more electrodes) configured to apply one or more voltages to one or more locations of the sample 320. In this regard, the one or more metrology subsystems 202 may generate voltage contrast imaging data.

[0054] It is recognized herein that the penetration depth of the particle beam 326 within the sample 320 may depend on the particle energy, such that a higher energy beam typically penetrates deeper into the sample. In one embodiment, one or more metrology subsystems 202b may utilize different particle energies to interrogate different layers of a device based on the penetration depth of the particle beam 326 into the sample 320. For example, one or more metrology subsystems 202b may utilize a relatively low energy electron beam (e.g., about 1 keV or less) and a higher energy beam (e.g., about 10 keV or more) to characterize a previously fabricated layer. It is recognized herein that the penetration depth as a function of particle energy may vary for different materials, such that the selection of particle energy for a particular layer may vary for different materials.

[0055] As mentioned above, the one or more metrology subsystems 202 may include a controller 204 communicatively coupled to the one or more metrology subsystems 202. The controller 204 may be configured to instruct the one or more metrology subsystems 204 to generate overlay signals based on one or more selected recipes. The controller 204 may further be configured to receive data including, but not limited to, the overlay signals from the one or more metrology subsystems 202. Furthermore, the controller 204 may be configured to determine an overlay associated with an overlay target based on the acquired overlay signals.

[0056] FIG. 4 shows a process flow diagram illustrating steps in a method 400 for measuring overlay on a specimen, in accordance with one or more embodiments of the present disclosure.

[0057] In step 402, a sample including one or more metrology targets 100 is illuminated. For example, the metrology system 200 may direct an illumination beam onto the sample 320. As used herein, the term "illumination beam" may refer to any beam of radiation, including, but not limited to, the optical illumination beam 304 and / or the particle beam 326.

[0058] In step 404, illumination emanating from one or more metrology targets 100 is detected. For example, optical illumination beam 304 and / or particle beam 326 may be detected. As another example, one or more metrology subsystems 202 may be configured to receive illumination emanating from one or more portions of one or more metrology targets 100 (e.g., the first set of target structures, the second set of target structures, the third set of target structures, the fourth set of target structures, and / or the fifth set of target structures).

[0059] One or more first overlay measurements are generated in step 406. For example, the controller 204 may be configured to generate one or more first overlay measurements of the specimen 320 based on one or more signals indicative of illumination emanating from one or more portions of a first set of target structures of one or more metrology targets 100.

[0060] One or more second overlay measurements are generated at step 408. For example, the controller 204 may be configured to generate one or more second overlay measurements of the specimen 320 based on one or more signals indicative of illumination emanating from one or more portions of the second set of target structures of the one or more metrology targets 100.

[0061] In some embodiments, the method 400 includes a step 410 in which one or more third overlay measurements are generated. For example, the controller 204 may be configured to generate one or more third overlay measurements of the specimen 320 based on one or more signals indicative of illumination emanating from one or more portions of a third set of target structures of the one or more metrology targets 100.

[0062] In some embodiments, the method 400 includes step 412, where one or more fourth overlay measurements are generated. For example, the controller 204 may be configured to generate one or more fourth overlay measurements of the specimen 320 based on one or more signals indicative of illumination emanating from one or more portions of a fourth set of target structures of the one or more metrology targets 100.

[0063] In some embodiments, the method 400 includes step 414, where one or more fifth overlay measurements are generated. For example, the controller 204 may be configured to generate one or more fifth overlay measurements of the specimen 320 based on one or more signals indicative of illumination emanating from one or more portions of a fifth set of target structures of the one or more metrology targets 100.

[0064] In step 416, an overlay error is determined based on at least two of the one or more first overlay measurements, the one or more second overlay measurements, the one or more third overlay measurements, the one or more fourth overlay measurements, or the fifth overlay measurement.

[0065] In some embodiments, method 400 may include one or more additional steps (not shown) to provide one or more overlay correctable values ​​based on at least the one or more overlay values ​​determined in step 416. For example, the one or more additional steps may include controller 204 generating one or more control signals (or corrections to the control signals) to adjust one or more parameters (e.g., manufacturing settings, configurations, etc.) of one or more process tools (e.g., lithography tools). The control signals (or corrections to the 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 the one or more process tools based on the one or more control signals (or corrections to the control signals). In some embodiments, controller 204 may alert a user to make one or more adjustments. In this sense, the one or more control signals may compensate for one or more manufacturing process errors of one or more process tools, thus enabling the one or more process tools to maintain overlay within a selected tolerance across multiple exposures on subsequent samples in the same or different lots.

[0066] FIG. 5 shows a process flow diagram illustrating steps in a method 500 of forming a metrology target 100 in accordance with one or more embodiments of the present disclosure.

[0067] In step 502, a first target structure set is formed on one or more layers of the metrology target 100, the first target structure set including at least one first target structure formed in at least one of a first work zone of the metrology target or a second work zone of the metrology target. Each first target structure includes one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction. The first target structure set may be fabricated through one or more process steps, such as, but not limited to, one or more deposition, lithography, or etch steps. The first target structure set may be formed using one or more process tools (e.g., lithography tools).

[0068] In step 504, a second target structure set is formed on one or more layers of the metrology target 100, the second target structure set including at least one second target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target. Each second target structure includes one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, and the first work zone of the metrology target and the second work zone of the metrology target are two-fold rotationally symmetric. The second target structure set may be fabricated through one or more process steps, such as, but not limited to, one or more deposition, lithography, or etch steps. The second target structure set may be formed using one or more process tools (e.g., lithography tools).

[0069] In some embodiments, method 500 includes step 506, in which a third target structure set is formed on one or more layers of metrology target 100, the third target structure set including at least one third target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target. The third target structure includes one or more third pattern elements formed along at least one of the first measurement direction or the second measurement direction. The third target structure set may be fabricated through one or more process steps, such as, but not limited to, one or more deposition, lithography, or etch steps. The third target structure set may be formed using one or more process tools (e.g., lithography tools).

[0070] In some embodiments, method 500 includes step 508, in which a fourth target structure set is formed on one or more layers of metrology target 100, the fourth target structure set including at least one fourth target structure formed in at least one of the first work zone of the metrology target or the second work zone of the metrology target. The fourth target structure includes one or more fourth pattern elements formed along at least one of the first measurement direction or the second measurement direction. The fourth target structure set may be fabricated through one or more process steps, such as, but not limited to, one or more deposition, lithography, or etch steps. The fourth target structure set may be formed using one or more process tools (e.g., lithography tools).

[0071] In some embodiments, method 500 includes step 510, in which a fifth target structure set is formed on one or more layers of metrology target 100, the fifth target structure set including at least one fifth target structure formed in at least one of a first work zone of the metrology target or a second work zone of the metrology target. The fifth target structure includes one or more fifth pattern elements formed along at least one of a first measurement direction or a second measurement direction. The fifth target structure set may be fabricated through one or more process steps, such as, but not limited to, one or more deposition, lithography, or etch steps. The fifth target structure set may be formed using one or more process tools (e.g., lithography tools).

[0072] All of the methods described herein may include storing results of one or more steps of a method embodiment in memory. The results may include any of the 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 are stored, they can be accessed in memory, used by any of the method or system embodiments 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 necessarily persist in memory indefinitely.

[0073] It is further contemplated that each of the above-described method embodiments may include any other step(s) of any other method(s) described herein. In addition, each of the above-described method embodiments may be performed by any of the systems described herein.

[0074] Those skilled in the art will recognize that the component operations, devices, objects, and accompanying discussion described herein are used as examples for conceptual clarity, and that various configuration modifications are contemplated. Thus, as used herein, the specific examples described and accompanying discussion are intended to be representative of their more general classes. In general, the use of any specific example is intended to represent that class, and the non-inclusion of specific components, operations, devices, and objects should not be construed as limiting.

[0075] As used herein, directional terms such as "up," "down," "up," "down," "up," "upper," "lower," "lower," and the like are intended to provide relative positions for purposes of description and are not intended to indicate an absolute frame of reference. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments.

[0076] With respect to the use of virtually any plural and / or singular term herein, those skilled in the art will be able to convert from the plural to the singular and / or from the singular to the plural as appropriate to the context and / or application. The various singular / plural permutations are not expressly set forth herein for ease of understanding.

[0077] The subject matter described herein illustrates different components that are, in some cases, included within or connected to other components. It should be understood that such depicted architectures are merely exemplary, and that in fact many other architectures that achieve the same functionality may be implemented. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Thus, any two components herein that combine to achieve a particular function can be considered to be “associated” with each other such that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated can also be considered to be “connected” or “coupled” to each other to achieve the desired functionality, and any two components that can be so associated can also be considered to be “couplable” with each other to achieve the desired functionality. Specific examples of what can be coupled include, but are not limited to, physically coupleable and / or physically interacting components and / or wirelessly interacting and / or wirelessly interacting components and / or logically interacting and / or logically interacting components.

[0078] It should further be understood that the present invention is defined by the appended claims. In general, those skilled in the art will understand that the terms used in this specification, and particularly in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but not limited to," etc.). Those skilled in the art will further understand that if a specific number of introduced claim recitations is intended, such intention will be explicitly recited in the claim; in the absence of such recitation, no such intention exists. For example, as an aid to understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce the claim recitations. However, the use of such phrases should not be interpreted as meaning that the introduction of a claim recitation with the indefinite article "a" or "an" limits any particular claim containing such an introduced claim recitation to an invention containing only one such recitation. The same applies to the use of express articles used to introduce claim recitations, even when the same claim includes the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should typically be interpreted to mean "at least one" or "one or more"). Those skilled in the art will also recognize that even when a specific number of introduced claim recitations is explicitly recited, such a recitation should typically be interpreted to mean at least the recited number (e.g., a bare recitation of "two recitations" without other modifiers typically means at least two recitations, or two or more recitations).Furthermore, in instances where a conventional expression similar to "such as at least one of A, B, and C" is used, generally such a configuration is intended in the sense that one skilled in the art would understand the conventional expression (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together). In instances where a conventional expression similar to "such as at least one of A, B, or C" is used, generally such a configuration is intended in the sense that one skilled in the art would understand the conventional expression (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together). Those skilled in the art will further appreciate that virtually any disjunctive word and / or phrase presenting two or more alternative terms, wherever it appears in the description, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0079] It is believed that the present disclosure and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes can be made in the form, construction, and arrangement of the elements without departing from the disclosed subject matter or sacrificing all of its material advantages. The illustrated forms are merely illustrative, and it is the intent of the following claims to embrace and include such modifications. It is further understood that the invention is defined by the claims.

Claims

1. A measurement target, a first target structure set formed on the specimen, the first target structure set including a first working zone and a second working zone, a first target structure formed in the first working zone and a second target structure formed in the second working zone, the first target structure set including periodic structures along one measurement direction, and an orientation of one or more patterns in the first working zone different from an orientation of one or more patterns in the second working zone; a second target structure set formed on the specimen, the second target structure set including a first work zone and a second work zone, a first target structure formed in the first work zone, a first portion of a second target structure formed in the first work zone, a second portion of the second target structure formed in the second work zone, the second target structure set including a periodic structure along the one measurement direction, and an orientation of one or more patterns in the first work zone different from an orientation of one or more patterns in the second work zone; Equipped with The first work zone and the second work zone have a non-rectangular polygonal shape in a top view, and the first work zone and the second work zone are combined to form a rectangular shape; the first working zone and the second working zone are at least two-fold rotationally symmetric about a center of rotational symmetry; a difference between the center of rotational symmetry of the first work zone and the center of rotational symmetry of the second work zone indicates an overlay error along the one measurement direction. Measurement target.

2. 1. A system comprising: a controller communicatively coupleable to one or more metrology subsystems, the controller including one or more processors configured to execute a set of program instructions maintained in a memory, the set of program instructions causing the one or more processors to: receiving, from the one or more metrology subsystems, one or more signals indicative of illumination emanating from a metrology target on the specimen, the metrology target on the specimen comprising: a first set of target structures formed on the specimen, the first set of target structures comprising a first work zone and a second work zone, wherein a first target structure is formed in the first work zone and a second target structure is formed in the second work zone, the first set of target structures comprising periodic structures along one measurement direction, wherein an orientation of one or more patterns in the first work zone differs from an orientation of one or more patterns in the second work zone; and a second set of target structures formed on the specimen, the second set of target structures comprising a first work zone and a second work zone, wherein a first target structure is formed in the first work zone and a second target structure is formed in the second work zone. a second target structure set, wherein a first portion of a second target structure is formed in the first work zone and a second portion of the second target structure is formed in the second work zone, the second target structure set including a periodic structure along the one measurement direction, and an orientation of one or more patterns in the first work zone differs from an orientation of one or more patterns in the second work zone, the first work zone and the second work zone are at least two-fold rotationally symmetric about a center of rotational symmetry, the first work zone and the second work zone have a non-rectangular polygonal shape in a top view, and the first work zone and the second work zone combine to form a rectangular shape, and a difference between the center of rotational symmetry of the first work zone and the center of rotational symmetry of the second work zone indicates an overlay error along the one measurement direction; generating at least a first overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the first set of target structures; generating at least a second overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the second set of target structures; determining an overlay error along the one measurement direction of the specimen based on the first overlay measurement and the second overlay measurement; a controller configured to cause A system comprising:

3. The first measurement is performed in at least one of the first measurement direction and the second measurement direction.

3. The system of claim 2, further comprising overlay metrology measurements along a direction.

4. The system of claim 2 , wherein the second metrology measurement comprises an overlay metrology measurement along at least one of the first measurement direction or the second measurement direction.

5. The system of claim 2 , wherein the specimen comprises a semiconductor wafer.

6. 1. A method for measuring overlay of a sample, comprising: irradiating a specimen having a metrology target, the metrology target including: a first set of target structures formed on the specimen, the first set of target structures including a first working zone and a second working zone, the first target structures being formed in the first working zone and the second target structures being formed in the second working zone, the first set of target structures including periodic structures along one measurement direction, an orientation of one or more patterns in the first working zone being different from an orientation of one or more patterns in the second working zone; and a second set of target structures formed on the specimen, the second set of target structures including a first working zone and a second working zone, the first target structures being formed in the first working zone and the first target structures being periodic structures along one measurement direction, an orientation of one or more patterns in the second working zone being different from an orientation of one or more patterns in the second working zone. a second target structure set, wherein a portion of the first target structure is formed in the first work zone, a second portion of the second target structure is formed in the second work zone, the second target structure set including a periodic structure along the one measurement direction, and an orientation of one or more patterns of the first work zone differs from an orientation of one or more patterns of the second work zone, wherein the first work zone and the second work zone are at least two-fold rotationally symmetric about a center of rotational symmetry, the first work zone and the second work zone have non-rectangular polygonal shapes in a top view, and the first work zone and the second work zone combine to form a rectangular shape, and a difference between the center of rotational symmetry of the first work zone and the center of rotational symmetry of the second work zone indicates an overlay error along the one measurement direction; detecting illumination emanating from the measurement target on the specimen; generating at least a first overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the first set of target structures; generating at least a second overlay measurement based on one or more signals indicative of illumination emanating from one or more portions of the second set of target structures; determining an overlay error along the one measurement direction of the specimen based on the first overlay measurement and the second overlay measurement; A method for providing

7. The method of claim 6 , wherein the first metrology measurement comprises an overlay metrology measurement along at least one of the first measurement direction or the second measurement direction.

8. The method of claim 6 , wherein the second metrology measurement comprises an overlay metrology measurement along at least one of the first measurement direction or the second measurement direction.

9. The method of claim 6 , wherein the specimen comprises a semiconductor wafer.

10. 1. A method of forming a metrology target, comprising: forming a first set of target structures on a specimen, the first target structure set including a first working zone and a second working zone, a first target structure formed in the first working zone and a second target structure formed in the second working zone, the first target structure set including periodic structures along one measurement direction, and an orientation of one or more patterns in the first working zone differs from an orientation of one or more patterns in the second working zone; forming a second set of target structures on the specimen, the second target structure set including a first work zone and a second work zone, a first target structure formed in the first work zone, a first portion of a second target structure formed in the first work zone, and a second portion of the second target structure formed in the second work zone, the second target structure set including periodic structures along the one measurement direction, an orientation of one or more patterns in the first work zone differs from an orientation of one or more patterns in the second work zone, the first work zone and the second work zone are rotationally symmetric at least two times about a center of rotational symmetry, the first work zone and the second work zone have a non-rectangular polygonal shape in a top view, and the first work zone and the second work zone combine to form a rectangular shape, and a difference between the center of rotational symmetry of the first work zone and the center of rotational symmetry of the second work zone indicates an overlay error along the one measurement direction; A method for providing

11. 10. The metrology target of claim 1, wherein the first working zone and the second working zone are formed in different physical layers of the specimen.

12. 10. The metrology target of claim 1, wherein the first working zone and the second working zone are formed in the same physical layer and have different features.

13. The metrology target of claim 1 , wherein the first work zone and the second work zone include a set of pattern elements that are periodic in one dimension.

14. The metrology target of claim 1 , wherein the first work zone and the second work zone include a set of pattern elements that are periodic in two dimensions.

15. The metrology target of claim 1 , wherein the first work zone and the second work zone are different sizes.

16. The measurement target according to claim 1 , wherein the first working zone and the second working zone are formed in a plurality of areas.

17. 3. The system of claim 2, wherein the first working zone and the second working zone are formed in different physical layers of the specimen.

18. The system of claim 2 , wherein the first work zone and the second work zone are formed on the same physical layer and have different features.

19. The system of claim 2 , wherein the first work zone and the second work zone include a set of pattern elements that are periodic in one dimension.

20. The system of claim 2 , wherein the first work zone and the second work zone include a set of pattern elements that are periodic in two dimensions.

21. The system of claim 2 , wherein the first work zone and the second work zone are different sizes.

22. 3. The system of claim 2, wherein the first work zone and the second work zone are formed in a plurality of areas.

23. 7. The method of claim 6, wherein the first working zone and the second working zone are formed in different physical layers of the specimen.

24. The first working zone and the second working zone are formed in the same physical layer and are different 7. The method of claim 6, further comprising the steps of:

25. The method of claim 6, wherein the first work zone and the second work zone include a set of pattern elements that are periodic in one dimension.

26. The method of claim 6, wherein the first work zone and the second work zone include sets of pattern elements that are periodic in two dimensions.

27. 7. The method of claim 6, wherein the first work zone and the second work zone are different sizes.

28. 7. The method of claim 6, wherein the first work zone and the second work zone are formed in multiple areas.

29. 11. The method of claim 10, wherein the first working zone and the second working zone are formed in different physical layers of the specimen.

30. The method of claim 10 , wherein the first working zone and the second working zone are formed in the same physical layer and have different features.

31. The method of claim 10, wherein the first work zone and the second work zone include a set of pattern elements that are periodic in one dimension.

32. The method of claim 10, wherein the first work zone and the second work zone include a set of pattern elements that are periodic in two dimensions.

33. The method of claim 10, wherein the first work zone and the second work zone are different sizes.

34. 11. The method of claim 10, wherein the first work zone and the second work zone are formed in a plurality of areas.

35. 1. A system comprising: a controller communicatively coupleable to a metrology subsystem, the controller including one or more processors configured to execute a set of program instructions maintained in a memory, the set of program instructions causing the one or more processors to: receiving from the metrology subsystem one or more images of a metrology target on the specimen, the metrology target including first and second work zones; a first set of target structures formed on the specimen, the first set of target structures including a first work zone and a second work zone, a first target structure formed in the first work zone and a second target structure formed in the second work zone, the first set of target structures including periodic structures along one measurement direction, an orientation of one or more patterns in the first work zone different from an orientation of one or more patterns in the second work zone; and a second set of target structures formed on the specimen. a second target structure set including a first work zone and a second work zone, wherein a first target structure is formed in the first work zone, a first portion of a second target structure is formed in the first work zone, and a second portion of the second target structure is formed in the second work zone, wherein the second target structure set includes a periodic structure along the one measurement direction, wherein the first work zone and the second work zone have a non-rectangular polygonal shape in a top view, and the first work zone and the second work zone combine to form a rectangular shape, and wherein an orientation of one or more patterns in the first work zone is different from an orientation of one or more patterns in the second work zone; and determining an overlay error between one or more layers of the specimen containing features of the first and second work zones based on a difference between the centers of rotational symmetry of either of the first and second work zones; a controller configured to cause A system comprising:

36. 36. The system of claim 35, wherein at least some of the features in the first and second working zones are located in a first layer of the specimen and at least some of the features in the first and second working zones are located in a second layer of the specimen.

37. 36. The system of claim 35, wherein the features of at least one of the first and second work zones are located in a different layer of the specimen including the metrology target than the features of at least one other of the first and second work zones.

38. 36. The system of claim 35, wherein the features of the first and second working zones are disposed in a single layer of the specimen.

39. 36. The system of claim 35, wherein the metrology subsystem includes an advanced imaging metrology (AIM) tool, and the first and second working zones provide AIM targets.

40. the metrology subsystem is a robust advanced imaging metrology (rAIM) tool; 36. The system of claim 35, comprising: the first and second working zones providing an rAIM target.

41. 36. The system of claim 35, wherein all of the first and second work zones have at least one of a common size or a common shape.

42. 36. The system of claim 35, wherein at least one of the first and second work zones has at least one of a different size or a different shape than another of the at least one of the first and second work zones.

43. 36. The system of claim 35, wherein the features of the first and second work zones are periodic along a single direction.

44. 44. The system of claim 43, wherein the difference between the centers of rotational symmetry of either of the first and second working zones indicates an overlay error along the single direction between one or more layers of the specimen containing the features of the first and second working zones.

45. 44. The system of claim 43, wherein the difference between the centers of rotational symmetry of either of the first and second working zones indicates an overlay error between one or more layers of the specimen containing the features of the first and second working zones along the single direction and a direction orthogonal to the single direction.

46. 36. The system of claim 35, wherein the difference between the centers of rotational symmetry of either of the first and second working zones indicates an overlay error along the two directions between one or more layers of the specimen containing the features of the first and second working zones.

Images