Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
  • G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
  • G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/70605—Workpiece metrology
  • G03F7/70681—Metrology strategies
  • G03F7/70683—Mark designs
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/70605—Workpiece metrology
  • G03F7/70616—Monitoring the printed patterns
  • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/0002—Inspection of images, e.g. flaw detection
  • G06T7/0004—Industrial image inspection
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/30—Subject of image; Context of image processing
  • G06T2207/30108—Industrial image inspection
  • G06T2207/30148—Semiconductor; IC; Wafer

Definitions

• the present disclosure is related generally to overlay metrology and, more particularly, to overlay metrology using metrology targets for one-dimensional measurement of periodic misregistration.
• Overlay metrology targets are typically designed to provide diagnostic information regarding the alignment of multiple layers of a sample by characterizing an overlay target having target features located on sample layers of interest. Further, the overlay alignment of the multiple layers is typically determined by aggregating overlay measurements of multiple overlay targets at various locations across the sample. However, the accuracy of an overlay measurement of an overlay metrology target may be sensitive to the particular location on a 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 overlay metrology samples. Current methods of overlay metrology frequently involve metrology along two measurement directions (e.g., two-dimensional metrology). However, two-dimensional metrology often requires metrology targets of a larger size. [0004] Accordingly, it may be desirable to provide a metrology target compatible with one-dimensional metrology methods, where the metrology target may occupy a smaller area of an overlay metrology sample.
• the metrology target includes a first target structure set formed on one or more layers of a sample, wherein the first target structure set comprises at least one first target structure formed within at least one of a first working zone of the metrology target or a second working zone of the metrology target, wherein each first target structure comprises one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction; and a second target structure set formed on one or more layers of the sample, wherein the second target structure set comprises at least one second target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein each second target structure comprises one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, and wherein a center of symmetry of the first working zone of the metrology target and a center of symmetry of the second working zone of the metrology target overlap when an overlay error between one or more
• the system includes a controller communicatively couplable to one or more metrology sub-systems, wherein the controller includes one or more processors, wherein the one or more processors are configured to execute a set of program instructions maintained in memory, wherein the set of program instructions is configured to cause the one or more processors to: receive, from the one or more metrology sub-systems, one or more signals indicative of illumination emanating from a metrology target of a sample, wherein the metrology target of the sample comprises: a first target structure set formed on one or more layers of the sample, wherein the first target structure set comprises at least one first target structure formed within at least one of a first working zone of the metrology target or a second working zone of the metrology target, wherein each first target structure comprises one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction; and a second target structure set formed on one or more layers of the sample, where
• a method of measuring overlay of a sample is disclosed, in accordance with one or more embodiments of the present disclosure.
• the method of measuring overlay of a sample may include illuminating a sample having a metrology target, the metrology target comprising: a first target structure set formed on one or more layers of the sample, wherein the first target structure set comprises at least one first target structure formed within at least one of a first working zone of the metrology target or a second working zone of the metrology target, wherein each first target structure comprises one or more first pattern elements formed along at least one of a first measurement direction or a second measurement direction, and a second target structure set formed on one or more layers of the sample, wherein the second target structure set comprises at least one second target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein each second target structure comprises one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, and wherein a center of symmetry of the first working zone of the metrology
• the method of forming a metrology target may include forming a first target structure set on one or more layers of a sample, wherein the first target structure set comprises at least one first target structure formed within at least one of a first working zone of the metrology target or a second working zone of the metrology target, wherein each first target structure comprises 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 target structure set on one or more layers of the sample, wherein the second target structure set comprises at least one second target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein each second target structure comprises one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, and wherein a center of symmetry of the first working zone of the metrology target and a center of symmetry of the second working zone of the metrology target,
• FIG. 1 A is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 B is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 C is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 D is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 E is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 F is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 1 G is a top view of a metrology target, in accordance with one or more embodiments of the present disclosure.
• FIG. 2 is a conceptual view of a metrology system, in accordance with one or more embodiments of the present disclosure.
• FIG. 3A illustrates a conceptual view of a metrology sub-system, in accordance with one or more embodiments of the present disclosure.
• FIG. 3B illustrates a conceptual view of a metrology sub-system, in accordance with one or more embodiments of the present disclosure.
• FIG. 4 is a process flow diagram depicting the steps of a method of measuring overlay of a sample, in accordance with one or more embodiments of the present disclosure.
• FIG. 5 is a process flow diagram depicting the steps of a method of forming a metrology target, in accordance with one or more embodiments of the present disclosure.
• a semiconductor device may be formed as multiple printed layers of patterned material on a substrate. Each printed layer may be fabricated 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 fabrication processes, the printed layers may be formed using one or more photo resist materials. For example, a photo resist material may be deposited onto the substrate. The photo resist material may then be exposed to illumination, wherein the illumination produces a latent target pattern on the photo resist 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.
• the photo resist material is exposed to illumination to produce a latent target pattern on the photo resist 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.
• each printed layer must typically be fabricated within selected tolerances to properly construct the final device.
• the relative placement of printed elements in each layer e.g., the overlay or the overlay parameters
• metrology targets may be fabricated on one or more printed layers to enable efficient characterization of the overlay of the layers. Deviations of overlay target features on a printed layer may thus be representative of deviations of printed characteristics of printed device features on that layer.
• overlay measured at one fabrication step may be used to generate correctables for precisely aligning a process tool (e.g., a lithography tool, or the like) for the fabrication of an additional sample layer in a subsequent fabrication step.
• a process tool e.g., a lithography tool, or the like
• Metrology targets may typically include well-defined printed elements designed to provide an accurate representation of one or more printing characteristics.
• measured characteristics of printed elements of a metrology target e.g., by a metrology tool
• metrology targets are typically characterized as having one or more measurement cells, where each cell includes printed elements in one or more layers on the sample. A metrology measurement may then be based on any combination of measurements of the size, orientation, or location (e.g., pattern placement) of printed elements in a single cell or between multiple cells.
• one or more cells of an overlay metrology target may include printed elements on two or more sample layers arranged such that the relative positions of elements of each layer may be indicative of offset errors (e.g., pattern placement errors (PPE)) in a particular layer or overlay errors associated with registration errors between sample layers.
• process-sensitive metrology targets 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, or the like) are indicative of one or more process metrics including, without limitation, the dose of illumination during a lithography step or a focal position of the sample in a lithography tool during a lithography step.
• Overlay metrology is typically performed by fabricating one or more overlay targets across a sample, where each overlay target includes features in sample layers of interest, which are fabricated at the same time as features associated with a device or component being fabricated.
• overlay errors measured at a location of an overlay target may be representative of overlay errors of device features.
• overlay measurements may be used to monitor and/or control any number of fabrication tools to maintain production of devices according to specified tolerances.
• overlay measurements of a current layer with respect to a previous layer on one sample may be utilized as feed-back data to monitor and/or mitigate deviations of the fabrication of the current layer on additional samples within a lot.
• overlay measurements of a current layer with respect to a previous layer on one sample may be utilized as feed-forward data to fabricate a subsequent layer on the same sample in a way that takes into account the existing layer alignments.
• Overlay targets typically include features specifically designed to be sensitive to overlay errors between sample layers of interest.
• An overlay measurement may then be carried out by characterizing the overlay target using an overlay metrology tool and applying an algorithm to determine overlay errors on the sample based on the output of the metrology tool.
• an overlay metrology tool is typically configurable according to a recipe including a set of measurement parameters utilized to generate an overlay signal.
• a recipe of an overlay metrology tool may include, but is not limited to, an illumination wavelength, a detected wavelength of radiation emanating from the sample, a spot size of illumination on the sample, an angle of incident illumination, a polarization of incident illumination, a position of a beam of incident illumination on an overlay target, a position of an overlay target in the focal volume of the overlay metrology tool, or the like.
• an overlay recipe may include a set of measurement parameters for generating an overlay signal suitable for determining overlay of two or more sample layers.
• Overlay metrology tools may utilize a variety of techniques to determine the overlay of sample layers.
• image-based overlay metrology tools may illuminate an overlay target (e.g., an advanced imaging metrology (AIM) target, a box-in- box metrology target, or the like) and capture an overlay signal including an image of overlay target features located on different sample layers.
• overlay may be determined by measuring the relative positions of the overlay target features.
• scatterometry-based overlay metrology tools may illuminate an overlay target (e.g., a grating-over-grating metrology target, or the like) and capture an overlay signal including an angular distribution of radiation emanating from the overlay target associated with diffraction, scattering, and/or reflection of the illumination beam. Accordingly, overlay may be determined based on models of the interaction of an illumination beam with the overlay target.
• optical metrology tools e.g., light-based metrology tools using electromagnetic radiation for illumination and/or detection
• optical metrology tools For the purposes of the present disclosure, the term “optical metrology tools,” “optical metrology techniques,” and the like indicate metrology tools and techniques using 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.
• EUV extreme ultraviolet
• VUV vacuum ultraviolet
• DUV deep ultraviolet
• UV ultraviolet
• IR infrared
• sample generally refers to a substrate formed of a semiconductor or non-semiconductor material (e.g., a wafer, or the like).
• a semiconductor or non-semiconductor material may include, but is not limited to, monocrystalline silicon, gallium arsenide, and indium phosphide.
• a sample may include one or more layers.
• such layers may include, but are not limited to, a resist (including a photoresist), a dielectric material, a conductive material, and a semiconductive material.
• resist including a photoresist
• One or more layers formed on a sample may be patterned or unpatterned.
• a sample may include a plurality of dies, each having repeatable patterned features. Formation and processing of such layers of material may ultimately result in completed devices.
• Many different types of devices may be formed on a sample, and the term sample as used herein is intended to encompass a sample on which any type of device known in the art is being fabricated.
• the term sample and wafer should be interpreted as interchangeable.
• the terms patterning device, mask and reticle should be interpreted as interchangeable.
• FIG. 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 within at least one of a first working zone 106 of the metrology target 100 or a second working zone 108 of the metrology target 100.
• Each of the first working zone 106 and the second working zone 108 may be located within 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., an x-direction), or a second measurement direction (e.g., a 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.
• the one or more first pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode.
• SCOL scatterometry-based overlay
• the one or more first 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).
• 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.
• the one or more first pattern elements may be compatible with any image-based overlay metrology mode, including, without limitation, 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• AIM advanced imaging metrology mode
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• AIMid advanced imaging metrology in-die
• 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, without limitation, one or more lithographic steps, one or more direct etching steps, or the like.
• the first target structure set and/or the first target structures 102a and 102b may be formed in any shape, including, without limitation, a square shape, a round shape, a rhombus-like shape, or a star-like shape.
• 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 within at least one of the first working zone 106 of the metrology target 100 or the second working 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 the first measurement direction (e.g., an x-direction), or the second measurement direction (e.g., a 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.
• the one or more second pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode.
• 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 structure known in the art to be suitable for diffracting, scattering, and/or reflecting an illumination beam).
• the one or more second pattern elements may be compatible with any image-based overlay metrology mode, including, without limitation, 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• AIM advanced imaging metrology mode
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• AIMid advanced imaging metrology in-die
• 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, without limitation, one or more lithographic steps, one or more direct etching steps, or the like.
• the second target structure set and/or the second target structures 104a and 104b may be formed in any shape, including, without limitation, a square shape, a round shape, a rhombus-like shape, or a star-like shape.
• the first working zone 106 and the second working zone 108 may be formed in such a manner that the first working zone 106 and the second working zone 108 may facilitate one or more overlay measurements based on the exploitation of rotational symmetry of one or more elements of the first working zone 106 and the second working zone 108.
• the first working zone 106 may be formed such that elements of the first working zone 106 (e.g., the one or more first target structures 102a and 102b and/or the one or more second target structures 104a and 104b) have a center of symmetry
• the second working zone 108 may be formed such that elements of the second working zone 108 (e.g., the one or more first target structures 102a and 102b and/or the one or more second target structures 104a and 104b) have a center of symmetry, where each of the foregoing centers of symmetry overlap at a center of symmetry 110 of the metrology target 100.
• first working zone 106 and the second working zone 108 may be two-fold rotationally symmetric, but embodiments of the present disclosure are not limited to the first working zone 106 and the second working zone 108 having two-fold rotational symmetry.
• first working zone 106 and the second working zone 108 may be four-fold rotationally symmetric. It is noted that the rotational symmetry of the first working zone 106 and the second working zone 108 may mitigate certain issues arising in connection with one or more metrology sub-systems, including, without limitation, wafer angular misplacement error, which may arise during measurement.
• the first working zone 106 may be formed at a position adjacent to the second working zone 108 (e.g., adjacent along an x-direction, as shown in FIG. 1A). In other embodiments, as shown in FIG. 1B, the first working zone 106 may be formed at a position adjacent, along a y-direction, to the second working zone 108. It is noted that the relative positions of the first working zone 106 and the second working zone 108 may be chosen in order to comply with design size or metrology operation requirements. For example, the metrology target 100 may be configured to occupy less space on a metrology sample based on the relative placement of the first working zone 106 and the second working zone 108.
• any target structure set e.g., the first target structure set and/or the second target structure set
• any target structure e.g., the first target structures 102a and 102b, and/or the second target structures 104a and 104b
• a first portion of the second target structure 104 may be formed within the first working zone 106
• a second portion of the second target structure 104 may be formed within the second working zone 108.
• first working zone 106 and the second working zone 108 occupying a single area of the metrology target 100.
• each of the first working zone 106 and the second working zone 108 may be formed in a plurality of areas on the metrology target 100.
• the metrology target 100 may include a third target structure set formed on one or more layers of the metrology target 100.
• the third target structure set may include one or more third target structures 112a and 112b.
• the one or more third second structures 112a and 112b may be formed within at least one of the first working zone 106 of the metrology target 100 or the second working zone 108 of the metrology target 100.
• the one or more third target structures 112a and 112b may include one or more third pattern elements configured for measurement along at least one of the first measurement direction (e.g., an x-direction), or the second measurement direction (e.g., a y-direction).
• the one or more third pattern elements may be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure.
• the one or more third pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode.
• 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).
• the one or more third pattern elements may be compatible with any image-based overlay metrology mode, including, without limitation, 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• AIM advanced imaging metrology mode
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• AIMid advanced imaging metrology in-die
• 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, without limitation, one or more lithographic steps, one or more direct etching steps, or the like.
• the third target structure set and/or the third target structures 112a and 112b may be formed in any shape, including, without limitation, a square shape, a round shape, a rhombus-like shape, or a star-like shape.
• the metrology target 100 may include a fourth target structure set formed on one or more layers of the metrology target 100.
• the fourth target structure set may include one or more fourth target structures 114a and 114b.
• the one or more fourth second structures 114a and 114b may be formed within at least one of the first working zone 106 of the metrology target 100 or the second working zone 108 of the metrology target 100.
• the one or more fourth target structures 114a and 114b may include one or more fourth pattern elements configured for measurement along at least one of the first measurement direction (e.g., an x-direction), or the second measurement direction (e.g., a y-direction).
• the one or more fourth pattern elements may be compatible with any metrology mode known in the art to be suitable for the purposes contemplated by the present disclosure.
• the one or more fourth pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode.
• 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).
• the one or more fourth pattern elements may be compatible with any image-based overlay metrology mode, including, without limitation, 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• AIM advanced imaging metrology mode
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• AIMid advanced imaging metrology in-die
• 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, without limitation, one or more lithographic steps, one or more direct etching steps, or the like.
• the fourth target structure set and/or the fourth target structures 114a and 114b may be formed in any shape, including, without limitation, a square shape, a round shape, a rhombus-like shape, or a star-like shape.
• 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 within at least one of the first working zone 106 of the metrology target 100 or the second working 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 the first measurement direction (e.g., an x-direction), or the second measurement direction (e.g., a 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.
• the one or more fifth pattern elements may be compatible with a scatterometry-based overlay (SCOL) metrology mode.
• 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).
• the one or more fifth pattern elements may be compatible with any image-based overlay metrology mode, including, without limitation, 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• 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 an overlay signal (e.g., an image of overlay target features located on different sample layers).
• AIM advanced imaging metrology mode
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• AIMid advanced imaging metrology in-die
• 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, without limitation, one or more lithographic steps, one or more direct etching steps, or the like.
• the fifth target structure set and/or the fifth target structures 116a and 116b may be formed in any shape, including, without limitation, a square shape, a round shape, a rhombus-like shape, or a star-like shape.
• each of the first working zone 106 and the second working zone 108 may be of any shape, including, without limitation, any polygonal shape.
• any target structure set 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
• any target structure 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
• a first portion of the second target structure 104 may be formed within the first working zone 106
• a second portion of the second target structure 104 may be formed within the second working zone 108.
• FIG. 2 illustrates a simplified block diagram of a metrology system 200, in accordance with one or more embodiments of the present disclosure.
• the metrology system 200 includes one or more metrology sub-systems 202
• the one or more metrology sub-systems 202 may be configured to operate in either an imaging more or a non-imaging mode.
• individual overlay target elements may be resolvable within the illuminated spot on the sample (e.g., as part of a bright-field image, a dark-field image, a phase-contrast image, or the like).
• the one or more metrology sub-systems 202 may operate as a scatterometry-based overlay (SCOL) metrology tool in which radiation from the sample is analyzed at a pupil plane to characterize the angular distribution of radiation from the sample (e.g., associated with scattering and/or diffraction of radiation by the sample).
• SCOL scatterometry-based overlay
• the one or more metrology sub-systems 202 may direct illumination to a sample and may further collect radiation emanating from the sample to generate an overlay signal suitable for the determination of overlay of two or more sample layers.
• the one or more metrology sub-systems may include any type of overlay metrology tool known in the art suitable for generating overlay signals suitable for determining overlay associated with overlay targets on a sample, including, without limitation, 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, and the like), any particle-based metrology tool (e.g., an electron- beam metrology tool), or a scatterometry-based overlay (SCOL) metrology tool.
• AIM advanced imaging metrology
• AIMid advanced imaging metrology in-die
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• SCOL scatterometry-based overlay
• the embodiments of the present disclosure are not limited to a metrology system 200 having only one metrology sub-system 202, and that the metrology system 200 may include at least two metrology sub-systems.
• the metrology system 200 may include an optical metrology tool and a scatterometry-based overlay (SCOL) metrology tool.
• SCOL scatterometry-based overlay
• the one or more metrology sub-systems 202 may be configurable to generate overlay signals based on any number of recipes defining measurement parameters for the acquiring an overlay signal suitable for determining overlay of an overlay target.
• a recipe the one or more metrology sub-systems 202 may include, but are not limited to, an illumination wavelength, a detected wavelength of radiation emanating from the sample, a spot size of illumination on the sample, an angle of incident illumination, a polarization of incident illumination, wave plan of the incident beam, a position of a beam of incident illumination on an overlay target, a position of an overlay target in the focal volume of the overlay metrology tool, or the like.
• the overlay metrology system 200 includes a controller 204 communicatively coupled to the one or more metrology sub-systems 202.
• the controller 204 may be configured to direct the one or more metrology sub-systems 202 to generate overlay signals based on one or more selected recipes.
• the controller 204 may be further configured to receive data including, but not limited to, overlay signals from the one or more metrology sub-systems 202. Additionally, the controller 204 may be configured to determine overlay associated with an overlay target based on the acquired overlay signals.
• the controller 204 includes one or more processors 206.
• the one or more processors 206 may be configured to execute a set of program instructions maintained in a memory medium 208, or memory.
• the controller 204 may be configured to determine an overlay error of a sample having one or more metrology targets 100 based on one or more overlay measurements of the sample.
• the metrology sub-system 202 may direct illumination to a sample having one or more metrology targets 100.
• the metrology sub-system 202 may be configured to further collect radiation emanating from the sample to generate one or more overlay measurements (or one or more signals indicative of one or more overlay measurements) suitable for the determination of overlay of two or more sample layers.
• the metrology sub-system 202 may be configurable to generate overlay signals based on any number of recipes defining measurement parameters for the acquiring an overlay signal suitable for determining overlay of an overlay target.
• a recipe the metrology sub-system 202 may include, but is not limited to, an illumination wavelength, a detected wavelength of radiation emanating from the sample, a spot size of illumination on the sample, an angle of incident illumination, a polarization of incident illumination, a position of a beam of incident illumination on an overlay target, a position of an overlay target in the focal volume of the overlay metrology tool, or the like.
• the controller 204 may be configured to determine an overlay error of a sample having one or more metrology targets 100 based on one or more overlay measurements of the sample. For example, the controller 204 may be configured to generate one or more overlay measurements of the sample based on one or more signals indicative of illumination emanating from one or more portions of the sample 320 (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). The one or more overlay measurements of the sample 320 may correspond to an overlay position of one or more layers of the sample 320.
• the one or more processors 206 of the controller 204 may include any processor or processing element known in the art.
• processors may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more micro processor 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)).
• ASIC application specific integrated circuit
• FPGA field programmable gate array
• DSP digital signal processors
• the one or more processors 206 may include any device configured to execute algorithms and/or instructions (e.g., program instructions stored in memory).
• the one or more processors 206 may be embodied as a desktop computer, mainframe computer system, workstation, image computer, parallel processor, networked computer, or any other computer system configured to execute a program configured to operate or operate in conjunction with the metrology system 200, as described throughout the present disclosure. Further, the steps described throughout the present disclosure may be carried out by a single controller 204 or, alternatively, multiple controllers. Additionally, the controller 204 may include one or more controllers housed in a common housing or within multiple housings. In this way, any controller or combination of controllers may be separately packaged as a module suitable for integration into metrology system 200. Further, the controller 204 may analyze data received from the one or more metrology sub-systems 202 and feed the data to additional components within the metrology system 200 or external to the metrology system 200.
• 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.
• the memory medium 208 may include a non-transitory memory medium.
• the memory medium 208 may include, but is not limited to, a read-only memory (ROM), a random-access memory (RAM), a magnetic or optical memory device (e.g., disk), a magnetic tape, a solid-state drive and the like.
• ROM read-only memory
• RAM random-access memory
• magnetic or optical memory device e.g., disk
• magnetic tape e.g., a magnetic tape
• solid-state drive e.g., solid-state drive and the like.
• memory medium 208 may be housed in a common controller housing with the one or more processors 206.
• the memory medium 208 may be located remotely with respect to the physical location of the one or more processors 206 and controller 204.
• the one or more processors 206 of controller 204 may access a
• 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, and the like.
• the user interface includes a display used to display data of the metrology system 200 to a user.
• the display of the user interface may include any display known in the art.
• 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.
• LCD liquid crystal display
• OLED organic light-emitting diode
• CRT display Those skilled in the art should recognize that any display device capable of integration with a user interface is suitable for implementation in the present disclosure.
• a user may input selections and/or instructions responsive to data displayed to the user via a user input device of the user interface.
• the controller 204 is communicatively coupled to one or more elements of the metrology system 200.
• the controller 204 may transmit and/or receive data from any component of the metrology system 200.
• the controller 204 may be communicatively coupled to the detector 320, 322 to receive one or more images from the detector 320, 322. Further, the controller 204 may direct or otherwise control any component of the metrology system 200 by generating one or more control signals for the associated components.
• the one or more metrology sub systems 202 may include an optical metrology sub-system 202a, such as a metrology sub-system including an optical metrology tool.
• the optical metrology sub-system 202a may include any type of optical metrology tool known in the art suitable for generating metrology data of a sample, including, without limitation, 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.
• the one or more metrology sub-systems 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.
• AIM advanced imaging metrology
• AIMid advanced imaging metrology in-die
• TAIM triple advanced imaging metrology
• rAIM robust advanced imaging metrology
• the one or more metrology sub-systems 202a may include an optical illumination source 302 configured to generate an optical illumination beam 304.
• the optical illumination beam 304 may include one or more selected wavelengths of radiation including, but not limited to, x-ray, ultraviolet (UV) light, visible light, or infrared (IR) light.
• the optical illumination source 302 may include any type of illumination source suitable for providing an optical illumination beam 304.
• the optical illumination source 302 is a laser source.
• the optical illumination source 302 may include, but is not limited to, one or more narrowband laser sources, a broadband laser source, a supercontinuum laser source, a white light laser source, or the like.
• the optical illumination source 302 may provide an optical illumination beam 304 having high coherence (e.g., high spatial coherence and/or temporal coherence).
• the optical illumination source 302 includes a laser- sustained plasma (LSP) source.
• LSP laser- sustained plasma
• the optical illumination source 302 may include, but is not limited to, a LSP lamp, a LSP bulb, or a LSP chamber suitable for containing one or more elements that, when excited by a laser source into a plasma state, may emit broadband illumination.
• the optical illumination source 302 includes a lamp source.
• the optical illumination source 302 may include, but is not limited to, an arc lamp, a discharge lamp, an electrode-less lamp, or the like.
• the optical illumination source 302 may provide an optical illumination beam 304 having low coherence (e.g., low spatial coherence and/or temporal coherence).
• the optical illumination source 302 directs the optical illumination beam 304 to the sample 320 via an illumination pathway 310.
• the illumination pathway 310 may include one or more illumination pathway lenses 308 or additional optical components 306 suitable for modifying and/or conditioning the optical illumination beam 304.
• 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 pathway 310 may further include an objective lens 316 configured to direct the optical illumination beam 304 to the sample 320.
• the sample 320 is disposed on a sample stage 322.
• the sample stage 322 may include any device suitable for positioning and/or scanning the sample 320 within the one or more metrology sub-systems 202a.
• the sample stage 322 may include any combination of linear translation stages, rotational stages, tip/tilt stages, or the like.
• the one or more metrology sub-systems 202a include one or more detectors 324 configured to capture light emanating from the sample 320 through a collection pathway 314.
• the collection pathway 314 may include, but is not limited to, one or more collection pathway lenses 312, 318 for collecting light from the sample 320.
• the one or more detectors 324 may receive light reflected or scattered (e.g., via specular reflection, diffuse reflection, and the like) from the sample 320 via one or more collection pathway lenses 312, 318.
• 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, or the like).
• the one or more detectors 324 may receive one or more diffracted orders of light from the sample 320 (e.g., 0-order diffraction, ⁇ 1 order diffraction, ⁇ 2 order diffraction, and the like).
• 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.
• a 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, or the like.
• a detector 324 may include a spectroscopic detector suitable for identifying wavelengths of light emanating from the sample 320.
• the one or more detectors 324 are positioned approximately normal to the surface of the sample 320.
• the one or more metrology sub-systems 202a includes a beamsplitter oriented such that the objective lens 316 may simultaneously direct the optical illumination beam 304 to the sample 320 and collect light emanating from the sample 320. Further, the illumination pathway 310 and the collection pathway 314 may share one or more additional elements (e.g., objective lens 316, apertures, filters, or the like).
• the one or more metrology sub-systems 202 may include a particle-based metrology sub-system 202b, such as a metrology sub system including an electron-beam metrology tool (e.g., a SEM, a CD-SEM, or the like).
• a particle-based metrology sub-system 202b such as a metrology sub system including an electron-beam metrology tool (e.g., a SEM, a CD-SEM, or the like).
• an electron-beam metrology tool e.g., a SEM, a CD-SEM, or the like.
• the one or more metrology sub-systems 202b may include a particle source 325 (e.g., an electron beam source, an ion beam source, or the like) to generate a particle beam 326 (e.g., an electron beam, a particle beam, or the like).
• the particle source 325 may include any particle source known in the art suitable for generating a particle beam 326.
• the particle source 325 may include, but is not limited to, an electron gun or an ion gun.
• the particle source 325 is configured to provide a particle beam with a tunable energy.
• particle source 325 may include, but is not limited to, an electron source configured provide an accelerating voltage in the range of 0.1 kV to 30 kV.
• a particle source 325 including an ion source may, but is not required to, provide an ion beam with an energy in the range of 1 to 50 keV.
• the one or more metrology sub-systems 202b may include one or more particle focusing elements 328.
• 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 compound system.
• the one or more particle focusing elements 328 include a particle objective lens 330 configured to direct the particle beam 326 to the sample 320 located on the sample stage 322.
• the particle source 325 may include any type of electron lenses known in the art including, but not limited to, electrostatic, magnetic, uni potential, or double-potential lenses.
• the one or more metrology sub-systems 202b may include at least one particle detector 332 to image or otherwise detect particles emanating from the sample 320.
• the particle detector 332 includes an electron collector (e.g., a secondary electron collector, a backscattered electron detector, or the like).
• the particle detector 332 includes a photon detector (e.g., a photodetector, an x-ray detector, a scintillating element coupled to photomultiplier tube (PMT) detector, or the like) for detecting electrons and/or photons from the sample surface.
• PMT photomultiplier tube
• the one or more metrology sub-systems 202b may include a plurality (e.g., at least two) particle detectors 332. It is noted herein that certain types of particle detectors 332 (e.g., photomultiplier detectors) may increase sensitivity of the one or more metrology sub-systems 202b.
• the description of the one or more metrology sub systems 202 are provided solely for illustrative purposes and should not be interpreted as limiting.
• the one or more metrology sub-systems 202 may include a multi-beam and/or a multi-column system suitable for simultaneously interrogating a sample 320.
• one or more metrology sub-systems 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.
• the one or more metrology sub systems 202 may generate voltage contrast imaging data.
• the penetration depth of the particle beam 326 in the sample 320 may depend on the particle energy such that higher-energy beams typically penetrate deeper into the sample.
• the one or more metrology sub systems 202b may utilize different particle energies to interrogate different layers of the device based on the penetration depth of the particle beam 326 into the sample 320.
• the one or more metrology sub-systems 202b may utilize a relatively low-energy electron beam (e.g., approximately 1 keV or less) and may utilize a higher energy beam (e.g., approximately 10 keV or higher) to characterize a previously fabricated layer.
• the penetration depth as a function of particle energy may vary for different materials such that the selection of the particle energy for a particular layer may vary for different materials.
• the one or more metrology sub-systems 202 may include a controller 204 communicatively coupled to the one or more metrology sub systems 202.
• the controller 204 may be configured to direct the one or more metrology sub-systems 204 to generate overlay signals based on one or more selected recipes.
• the controller 204 may be further configured to receive data including, but not limited to, overlay signals from the one or more metrology sub-systems 202. Additionally, the controller 204 may be configured to determine overlay associated with an overlay target based on the acquired overlay signals.
• FIG. 4 illustrates a process flow diagram depicting the steps of a method 400 of measuring overlay of a sample, in accordance with one or more embodiments of the present disclosure.
• a sample including one or more metrology targets 100 is illuminated.
• the metrology system 200 may direct an illumination beam onto the sample 320.
• illumination beam may refer to any radiant beam, including, without limitation, the optical illumination beam 304 and/or the particle beam 326.
• Step 404 illumination emanating from the one or more metrology targets 100 is detected.
• the optical illumination beam 304 and/or the particle beam 326 may be detected.
• the one or more metrology sub-systems 202 may be configured to receive illumination emanating from one or more portions of the one or more metrology targets 100 (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).
• one or more first overlay measurements are generated.
• the controller 204 may be configured to generate one or more first overlay measurements of the sample 320 based on one or more signals indicative of illumination emanating from one or more portions of the first target structure set of the one or more metrology targets 100.
• Step 408 one or more second overlay measurements are generated.
• the controller 204 may be configured to generate one or more second overlay measurements of the sample 320 based on one or more signals indicative of illumination emanating from one or more portions of second target structure set of the one or more metrology targets 100.
• the method 400 includes a Step 410, wherein one or more third overlay measurements are generated.
• the controller 204 may be configured to generate one or more third overlay measurements of the sample 320 based on one or more signals indicative of illumination emanating from one or more portions of the third target structure set of the one or more metrology targets 100.
• the method 400 includes a Step 412, wherein one or more fourth overlay measurements are generated.
• the controller 204 may be configured to generate one or more fourth overlay measurements of the sample 320 based on one or more signals indicative of illumination emanating from one or more portions of the fourth target structure set of the one or more metrology targets 100.
• the method 400 includes a Step 414, wherein one or more fifth overlay measurements are generated.
• the controller 204 may be configured to generate one or more fifth overlay measurements of the sample 320 based on one or more signals indicative of illumination emanating from one or more portions of the fifth target structure set of the one or more metrology targets 100.
• 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 measurements.
• the method 400 may include one or more additional steps (not shown) wherein one or more overlay correctables are provided based on the one or more overlay values determined in at least Step 416.
• the one or more additional steps may include the controller 204 generating one or more control signals (or corrections to the control signals) for adjusting one or more parameters (e.g., fabrication settings, configuration, and the like) of one or more process tools (e.g., lithographic tools).
• the control signals (or corrections to the control signals) may be provided by the controller 204 as part of a feedback and/or feedforward control loop.
• the controller 204 may cause the one or more process tools to execute one or more adjustments to the 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, the controller 204 may alert a user to make the one or more adjustments. In this sense, the one or more control signals may compensate for errors of one or more fabrication processes of the one or more process tools, and thus may enable the one or more process tools to maintain overlay within selected tolerances across multiple exposures on subsequent samples in the same or different lots.
• FIG. 5 illustrates a process flow diagram illustrating the steps of a method 500 of forming a metrology target 100, in accordance with one or more embodiments of the present disclosure.
• a first target structure set is formed on one or more layers of the metrology target 100, wherein the first target structure set comprises at least one first target structure formed within at least one of a first working zone of the metrology target or a second working zone of the metrology target, wherein each first target structure comprises 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, lithographic, or etching steps.
• the first target structure set may be formed using one or more process tools (e.g., lithographic tools).
• a second target structure set is formed on one or more layers of the metrology target 100, wherein the second target structure set comprises at least one second target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein each second target structure comprises one or more second pattern elements formed along at least one of the first measurement direction or the second measurement direction, and wherein the first working zone of the metrology target and the second working 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, lithographic, or etching steps.
• the second target structure set may be formed using one or more process tools (e.g., lithographic tools).
• the method 500 includes a Step 506, wherein a third target structure set is formed on one or more layers of the metrology target 100, wherein the third target structure set comprises at least one third target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein the third target structure comprises 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, lithographic, or etching steps.
• the third target structure set may be formed using one or more process tools (e.g., lithographic tools).
• the method 500 includes a Step 508, wherein a fourth target structure set is formed on one or more layers of the metrology target 100, wherein the fourth target structure set comprises at least one fourth target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein the fourth target structure comprises 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, lithographic, or etching steps.
• the fourth target structure set may be formed using one or more process tools (e.g., lithographic tools).
• the method 500 includes a Step 510, wherein a fifth target structure set is formed on one or more layers of the metrology target 100, wherein the fifth target structure set comprises at least one fifth target structure formed within at least one of the first working zone of the metrology target or the second working zone of the metrology target, wherein the fifth target structure comprises one or more fifth pattern elements formed along at least one of the first measurement direction or the 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, lithographic, or etching steps.
• the fifth target structure set may be formed using one or more process tools (e.g., lithographic tools).
• All of the methods described herein may include storing results of one or more steps of the method embodiments 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.
• the results can be accessed in the memory and 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, and the like.
• the results may be stored “permanently,” “semi-permanently,” temporarily,” or for some period of time.
• the memory may be random access memory (RAM), and the results may not necessarily persist indefinitely in the memory.
• each of the embodiments of the method described above may include any other step(s) of any other method(s) described herein.
• each of the embodiments of the method described above may be performed by any of the systems described herein.
• One skilled in the art will recognize that the herein described components operations, devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components, operations, devices, and objects should not be taken as limiting.
• any two components so associated can also be viewed as being “connected,” or “coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “couplable,” to each other to achieve the desired functionality.
• Specific examples of couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.

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