KR102473825B1 - Overlay targets with orthogonal underlayer dummyfill - Google Patents

Abstract

The present disclosure relates to the design and use of overlay targets having orthogonal underlayer dummy fills. According to various embodiments, an overlay target may include one or more segmented overlay pattern elements forming at least one overlay target structure. The overlay target may further include one or more inactive pattern elements forming at least one dummyfill target structure. Each of the one or more inactive pattern elements may include a dummy fill segmented along an axis orthogonal to the segmentation axis of the at least one proximal overlay pattern element. In some embodiments, each of the target structures or layers may be formed in a separate processing layer sequentially disposed on a substrate, such as a silicon wafer. In some embodiments, the overlay and dummyfill target structures may be 2- or 4-fold rotationally symmetric to allow for certain manufacturing or metrology advantages.

Description

Overlay target with orthogonal underlayer dummy fill {OVERLAY TARGETS WITH ORTHOGONAL UNDERLAYER DUMMYFILL}

The present disclosure relates generally to the field of overlay targets for overlay metrology, and more specifically to designing and using overlay targets with orthogonal underlayer dummyfills.

Semiconductor devices are usually manufactured by creating a plurality of layers disposed on a substrate such as a silicon wafer. Typically, the alignment between the various processing layers is controlled to ensure the functionality and performance of the resulting device. Misalignment between device features or structures formed in two or more successive layers is often referred to as overlay error. The ability to detect and correct for overlay errors between patterned layers on a wafer is critical to the manufacture of integrated circuits and other semiconductor devices.

Overlay metrology is a known technique for determining overlay error or misalignment between patterned device layers, typically by analyzing an overlay “target” or “mark” placed proximate to one or more device layers of interest. For example, overlay measurements can be performed via test patterns (ie, one or more overlay target structures) that are printed along with the various patterned device layers on a wafer. The overlay metrology system may include an imaging tool configured to collect image frames that are analyzed by the processing unit to determine relative displacement or misalignment of pattern elements comprising the device and target layers.

Currently, several techniques can be applied to maintain or improve the process compatibility of the substrates supporting the overlay target. For example, one or more patterned layers of dummy fills (i.e., non-functional structures or features) are placed on a substrate to achieve spatial or physical characteristics required by specific semiconductor manufacturing or test equipment design rules. It can be. Moreover, the pattern elements forming the target structures or layers of the metrology target may be composed of features that are nominally smaller than the segmentation or sub-pattern selected to improve process compatibility.

Despite existing solutions, deficiencies in the technology continue to cause process damage to overlay metrology targets or lack of target compatibility with semiconductor manufacturing design rules. Some deficiencies of the current state of the art include: dishing near or within the target due to chemical mechanical polishing, etch bias near the target due to incompatible pattern density, subsequent parasitic capacitance in the fabricated device due to violation of the design rule of the target, These include lithographic incompatibility of the target causing metrology bias in overlay measurements, and increased metrology footprint on the reticle and wafer due to excessive target size.

The present disclosure is directed to an overlay target design that includes orthogonal underlayer dummyfills to address one or more deficiencies of the current state of the art. In one aspect, the present disclosure relates to an overlay target comprising one or more segmented overlay pattern elements forming at least one overlay target structure. The overlay target further includes one or more inactive pattern elements forming at least one dummyfill target structure. Each of the one or more inactive pattern elements may include a dummy fill segmented along an axis orthogonal to the segmentation axis of the at least one proximal overlay pattern element. According to various embodiments, each of the target structures or layers may be formed in a separate processing layer sequentially disposed on a substrate, such as a silicon wafer.

In another aspect, the present disclosure relates to an overlay metrology system for performing overlay measurements on a substrate. The system can include a sample stage configured to support a substrate having an overlay target disposed thereon, the overlay target including one or more segmented overlay pattern elements forming at least one overlay target structure, the overlay target further comprises one or more inactive pattern elements forming at least one dummyfill target structure, each of the one or more inactive pattern elements segmented along an axis orthogonal to the segmentation axis of the at least one proximal overlay pattern element; May include a misspelling. The system may further include at least one illumination source configured to illuminate the overlay target and at least one detector configured to receive illumination reflected, scattered or radiated from the overlay target. At least one computing system communicatively coupled to the detector uses information (e.g., one or more image frames or contrast data) associated with the light reflected, scattered, or radiated from the overlay target to detect at least two layers disposed on the substrate. It may be configured to determine misalignment of the liver. In some embodiments, overlay and dummyfill target structures are twofold or fourfold rotationally symmetric to allow for certain manufacturing or metrology advantages. However, 2-fold or 4-fold rotational symmetry is not required by all applications, such as those using scatterometry overlay (SCOL) or diffraction based overlay (DBO) metrology targets.

In another aspect, the present disclosure relates to a method of performing overlay metrology on a substrate, the method comprising: illuminating an overlay target disposed on the substrate; detecting reflected, scattered or emitted illumination from the overlay target; and determining a misalignment between at least two layers disposed on the substrate using information associated with the detected illumination, wherein the overlay target comprises one or more segmented overlay pattern elements forming at least one overlay target structure. and the overlay target further comprises one or more inactive pattern elements forming at least one dummyfill target structure, each of the one or more inactive pattern elements being orthogonal to a segmentation axis of the at least one proximately disposed overlay pattern element. It may include a dummy fill segmented along an axis.

It will be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and do not necessarily limit the present disclosure. The accompanying drawings, which are incorporated in and constitute a part of the specification, represent the subject matter of the present disclosure. Together, the description and drawings serve to explain the principles of the present disclosure.

Many of the advantages of the present disclosure may be better understood by those skilled in the art by referring to the accompanying drawings.
1A illustrates an overlay target, in accordance with an embodiment of the present disclosure.
1B illustrates a portion of an overlay target, in accordance with an embodiment of the present disclosure, where a segmentation axis of a dummy fill pattern element is orthogonal to a segmentation axis of an overlay pattern element.
2A illustrates a two-fold/four-fold symmetric overlay target, in accordance with an embodiment of the present disclosure.
2B illustrates an overlay target structure and a dummyfill target structure of a 2/4 times symmetric overlay target, in accordance with an embodiment of the present disclosure.
3A illustrates a two-fold/four-fold symmetric overlay target, in accordance with an embodiment of the present disclosure.
3B illustrates an overlay target structure and a dummyfill target structure of a 2/4 times symmetric overlay target, in accordance with an embodiment of the present disclosure.
4A illustrates a 2/4 symmetric overlay target, in accordance with an embodiment of the present disclosure.
4B illustrates an overlay target structure and a dummyfill target structure of a 2/4 times symmetric overlay target, in accordance with an embodiment of the present disclosure, where each of the target structures includes a plurality of pattern elements.
5A shows a two-fold symmetric overlay target, in accordance with an embodiment of the present disclosure, wherein a first portion of overlay pattern elements is printed onto a dummy fill according to a first exposure.
5B shows a two-fold symmetric overlay target, in accordance with an embodiment of the present disclosure, wherein a second portion of the overlay pattern elements is printed onto the dummy fill according to a second exposure.
6 illustrates an overlay target, in accordance with an embodiment of the present disclosure.
7 is a block diagram illustrating an overlay metrology system, in accordance with an embodiment of the present disclosure.
8 is a flowchart illustrating a method of performing overlay metrology, according to an embodiment of the present disclosure.

Reference will now be made in detail to the disclosed subject matter appearing in the accompanying drawings.

1A-8 generally illustrate the design and use of an overlay with an orthogonal underlayer dummyfill, in accordance with various embodiments of the present disclosure. US patent application Ser. No. 13/186,144 describes, at least in part, the orthogonal alignment of a dummyfill with an overlay target structure disposed below or over the dummyfill. Additionally, US patent application Ser. No. 12/455,640 describes a metrology target that at least partially includes a dummy fill, referred to as a "dummy field." US Patent Application Serial Nos. 13/186,144 and 12/455,640 are incorporated by reference as if fully set forth herein. The following embodiments are provided for illustrative purposes, and it is to be understood that the features and apparatus described below may be combined to create additional embodiments. For example, those skilled in the art will appreciate that some of the following embodiments can be combined to achieve an overlay metrology system or overlay target that conforms to a set of manufacturing design rules or satisfies a selected level of process compatibility.

1A shows an overlay metrology target 100, in accordance with an embodiment of the present disclosure. The overlay target 100 may include a plurality of target structures. In some embodiments, the target structures are sequentially disposed on a substrate such as a silicon wafer and fabricated in separate process layers. The overlay target 100 may include one or more inactive pattern elements 102a-102d consisting essentially of segmented dummyfills. The inactive pattern elements 102a-102d may form at least a first “dummyfill” target structure. The overlay target 100 includes one or more overlay pattern elements 104a formed from overlay features known in the art, such as those described or referenced in U.S. Patent Application Serial Nos. 13/186,144 and/or 12/455,640. -104d) may be further included.

The overlay pattern elements 104a - 104d may form at least a second "overlay" target structure disposed proximate to the dummyfill target structure. For example, an overlay target structure may be subsequently disposed on a substrate over a dummyfill target structure. Accordingly, the dummyfill target structure may be referred to as a "dummyfill underlayer". Dummy fills 102a-102d and/or overlay pattern elements 104a-104d may be segmented according to a make/test design rule, or according to a selected range or selected deviation from a design rule. As shown in FIG. 1B , each dummyfill pattern element 102 can be segmented along a first “dummyfill” segmentation axis 106, which first “dummyfill” segmentation axis 106 is a dummyfill. Orthogonal to a second "overlay" segmentation axis 108 corresponding to at least one segmented overlay pattern element 104 disposed above or below the pattern element 102. Moreover, in some embodiments, the at least first set of one or more dummyfill pattern elements 102a, 102c is segmented in a direction orthogonal to the segmentation direction of the second set of one or more dummyfill pattern elements 102b, 102d. do.

Segmented dummyfill pattern elements 102 are disposed on an empty area reserved for pattern elements, such as device or overlay pattern elements, that are subsequently disposed along one or more successive processing layers of the substrate. A dummy fill may be included. Dummyfill pattern elements 102 may further include an inner edge (e.g., one or more rectangular openings) enabling location estimation of at least one overlay or dummyfill pattern element constituting a portion of overlay target 100. have. 2A and 2B show a dummy fill target structure formed of a plurality of dummy fill pattern elements 202a to 202d disposed proximate to an overlay target structure 203 formed of a plurality of overlay pattern elements 204a to 204d ( 201) shows a 2/4-fold symmetric overlay target 200. In some embodiments, each target structure 201 and 203 is 2-fold or 4-fold rotationally symmetric, such that the resulting target structure formed by the placement of the overlay target structure 203 over the dummyfill target structure 201 ( 200) is correspondingly 2-fold or 4-fold rotationally symmetric. In some embodiments, for example, target 200 is four-fold rotationally symmetric. Furthermore, each of the dummyfill pattern elements 202a-202d may include a single axis segmentation dummyfill that forms a two-fold rotationally symmetrical subpattern.

In some embodiments, dummyfill subpatterns 202a-202d are segmented along a selected axis, where the size and spacing of the dummyfill segments along the segmentation axis are printed over the dummyfill pattern elements 202a-202d. It is selected according to the spatial or physical characteristics of the overlay pattern elements 204a-204d. For example, dummyfill segmentation may be performed on the feature size, spacing of subsequently printed overlay pattern elements 204a-204d to avoid contamination of metrology signals associated with overlay features disposed on the substrate orthogonal to the dummyfill segment. , and/or may be selected according to segmentation. In some embodiments, the pitch and/or feature size of the dummyfill segmentation is substantially greater than the minimum design rule for an exposure tool, such as a lithographic exposure tool, through which the dummyfill subpatterns are exposed (i.e. , printed or disposed on the surface of the substrate). Oversize segmentation can advantageously reduce end-of-line pullback (eg, asymmetric pullback).

As shown in FIG. 3A , overlay metrology target 300 may include single axis segmented dummyfill pattern elements 302a - 302d with closely spaced overlay pattern elements 304a - 304d , whereby , the boundaries of subsequently overlaid subpatterns are completely within the boundaries formed by the dummyfill subpatterns. 3B further illustrates a dummy fill target structure 301 formed from dummy fill pattern elements 302a-302d and an overlay target structure 303 formed from overlay pattern elements 304a-304d. In some embodiments, the selected distance between the boundary of the dummyfill subpatterns and the boundary of the overlaid subpatterns is greater than a predetermined light blocking zone. The distance between the boundaries may be greater than the predetermined light blocking zone only in an axis perpendicular to or parallel to the dummyfill segmentation axis, or in both parallel and perpendicular directions.

As shown in FIGS. 4A and 4B , the 2/4 rotationally symmetric overlay target 400 may include a plurality of overlay and dummyfill subpatterns in each quadrant. For example, each quadrant of overlay target 400 may include six dummyfill pattern elements 402a - 402d forming dummyfill target structure 401 . Each quadrant may further include five overlay pattern elements 404a - 404d forming an overlay target structure 403 disposed on top of the dummy fill target structure 401 . A two-fold rotationally symmetric overlay target can be similarly designed using multiple overlay and dummyfill subpatterns on the top and bottom halves, respectively, or on the right and left halves, respectively.

In some embodiments, portions of the dummyfill or overlay subpatterns are printed separately on the substrate in two or more side by side exposures. For example, in the embodiment of overlay target 500 shown in FIGS. 5A and 5B , overlay pattern elements 504a and 504b are formed according to a first exposure (see FIG. 5A ) and a second exposure (see FIG. 5B ). It is printed on the dummy fill underlayers 502a and 502b. Segmented dummyfill subpatterns can be printed in separate exposures without blocking zones between overlay subpatterns. Moreover, the dummyfill segmentation can be the same for each of the dummyfill subpatterns and can be aligned according to the lithographic overlay tolerance. In some embodiments, the overlay target may further include subsequently overlaid segmented dummyfill subpatterns aligned within the lithographic overlay pattern and having the same segmentation.

In some embodiments, such as the example embodiment shown in FIGS. 2A and 2B , the overlay target 200 has an interior that can be measured to estimate a position of at least one pattern element defining an overlay or dummyfill subpattern. It may further include overlay subpatterns 204a-204d and/or dummyfill subpatterns 202a-202d with edges (ie, including rectangular openings or "windows"). Thus, the overlay target 200 may include a device that enables subpattern position estimation in directions parallel and/or perpendicular to the segmentation axis of each overlay or dummyfill pattern element. In some embodiments, subpattern position estimation may be performed only in the direction perpendicular to the dummyfill segmentation line to avoid enhanced scanner aberration sensitivity, particularly at edge locations, as a function of scanner focus. Alternatively, subpattern position estimation may be performed only in a direction parallel to the dummyfill segmentation line to avoid design rule violation.

Certain embodiments of an overlay target may be advantageous for specific metrology or process compatibility requirements. In one embodiment, for example, a 4-fold rotationally symmetric overlay target may include multiple layers (eg, four layers). The overlay target of each quadrant may include two segmented dummyfill subpatterns enabling measurement of the overlay along a first axis orthogonal to the dummyfill segmentation. Each quadrant may further include two segmented overlay subpatterns subsequently disposed over the dummyfill pattern elements. The overlaid subpatterns may be arranged to enable measurement of the overlay along a second axis orthogonal to the first axis (ie, the measurement axis for dummyfill subpatterns). Alternatively, the overlaid subpatterns may be arranged to allow measurement of the overlay along a second axis parallel to the first axis.

In another exemplary embodiment, the (two-layer) four-fold rotationally symmetric overlay target in each quadrant is a single axis segmented dummy fill that substantially fills the respective quadrant except for openings (or windows) with inner edges. May contain subpatterns. The inner edge of the opening may be measured for subpattern location estimation in a direction parallel to the dummyfill segmentation. The target may further include a segmented overlay subpattern subsequently disposed over the dummyfill subpattern. Overlay subpatterns can be segmented according to manufacturing design rules. Additionally, the edges of the overlay subpattern may be measured for subpattern position estimation in a direction parallel to the dummyfill segmentation axis.

In another exemplary embodiment, a two-fold rotationally symmetric (four layer) overlay target may include four segmented dummyfill subpatterns (two in the X direction and two in the Y direction). Each of the dummyfill subpatterns may be arranged to enable measurement of overlay along a separate measurement axis. The overlay target may further include 12 segmented overlay subpatterns (6 in the X direction and 6 in the Y direction). Each of the subsequently printed overlay subpatterns over the dummyfill subpatterns may be arranged to further enable measurement of the overlay along a separate measurement axis.

Those skilled in the art will understand that the nature of the above exemplary embodiments, such as those described herein, are to be understood as exemplary and are not intended to limit the present disclosure in any way. In some embodiments, the segmentation is based on a feature size of the device or overlay layers exceeding a minimum design rule, thereby increasing the process window of the subpattern to be larger than that of the resulting device. Moreover, the segmentation can be relatively small compared to the geometry of the subpattern itself. According to various embodiments, a segmented single axial dummyfill underlayer may cover at least 50% of the processing layer to improve metrology performance and process compatibility. For example, the segmented dummyfill may cover most of at least one layer disposed on the substrate.

Various variations in segmentation spacing/pitch, number of processing layers, symmetry, and other properties of the metrology target are contemplated. The foregoing embodiments illustrate various features, but are not intended to limit the present disclosure in any way. For example, while various embodiments herein describe 2- or 4-fold rotationally symmetric overlay metrology targets, 2-/4-fold symmetry is not required for all applications. In some embodiments shown in FIG. 6 , the overlay metrology target 600 is neither entirely 2-fold rotationally symmetric nor 4-fold rotationally symmetric. However, various portions of overlay target 600, such as individual subpatterns or groupings of two or more subpatterns, may be at least twice symmetrical.

Some applications, such as SCOL or DBO instrumentation, do not require 2/4 symmetric targets. For example, the overlay target 600 includes a first plurality of overlay pattern elements 602a-602d forming a first overlay target structure, and a second plurality of overlay pattern elements forming a second overlay target structure ( 604a to 604d), and both target structures formed successively on the dummy fill underlayer may include orthogonally aligned inactive pattern elements 606a to 606d. As further illustrated in FIG. 6 , dummy fill segmentation (ie, spacing and pitch) in the first (X) direction may be different from dummy fill segmentation in the second (Y) direction.

In some embodiments, the target 600 allows overlay measurement in a first direction according to a first target structure or layer defined by the first plurality of overlay pattern elements 602a - 602d. Moreover, the overlay can be measured in at least a second direction according to a second target structure or layer defined by the second plurality of overlay pattern elements 604a - 604d. Those skilled in the art will appreciate that the number of layers and types (eg, device, dummyfill, or overlay layers) may be varied without departing from the scope of the present disclosure.

7 is a block diagram illustrating an overlay metrology system 700, in accordance with an embodiment of the present disclosure. The overlay metrology system 700 may include an optical metrology system, such as the system described or referenced in US Patent Application Serial No. 13/186,144. The system 700 can include at least one illumination source 702 configured to illuminate an overlay metrology target 704 disposed on a substrate 706, wherein the overlay target 704 is configured according to the embodiments above. include the target. The substrate 706 can be supported by a sample stage 708, which can include at least one linear or rotary actuator that translates or rotates the substrate into a selected position.

The system is configured to direct illumination from an illumination source 702 along at least a first (object) path to a second (reference) path described by an overlay target 704 and a reference optic 716, such as a reference mirror. One beam splitter 712 may be included. Illumination reflected, scattered, or radiated from the surface of the substrate 706 including the overlay target 704 may be collected through an optical lens 714 and directed along a collection path to at least one detector 710. have. At least one computing system 718 in communication with detector 710 may be configured to collect imaging data associated with illumination received from the surface of substrate 706 . Computing system 718 uses information (e.g., image frames or contrast data) associated with the imaging data collected for overlay target 704 to determine overlay error or spatial misalignment between at least two layers formed on substrate 706. It can be configured to determine.

It should be appreciated that the various steps and functions described throughout this disclosure may be performed by a single computing system or by multiple computing systems. For example, computing system 718 may include, but is not limited to, a personal computing system, mainframe computing system, workstation, visual computer, parallel processor, or any other device known in the art. In general, computing system 718 may include at least one single-core or multi-core processor configured to execute program instructions 722 from at least one delivery medium 720 .

8 generally shows a method 800 of performing overlay metrology according to overlay metrology system 700 . However, it is recognized that one or more steps of method 800 may be practiced with a system or device that varies from the foregoing embodiments of system 700 without departing from the essence of the present disclosure. In an embodiment, method 800 may include at least the following steps. In step 802, the overlay metrology target 704 disposed on the substrate 706 is illuminated. In step 804, illumination reflected, scattered or emitted from the target is collected through collection optics, such as an optical lens 714, and directed to at least one imaging detector 710, such as a TDI camera. At step 806, the imaging data is processed to determine misalignment between at least two layers disposed on the substrate. It is noted herein that imaging data may be processed according to any overlay metrology algorithm known in the art. For example, a spatial comparison between a target structure formed from device features and/or pattern elements forming the pattern may be performed to determine relative displacement (ie, overlay error).

In some embodiments, only the inner edges of the dummy fill pattern elements are measured to avoid abrasive damage. In some embodiments, a position of at least one dummyfill pattern element is determined through measurement in a first direction, and a position of at least one overlay pattern element subsequently disposed on substrate 706 is determined in a second direction ( eg along an axis orthogonal to the first direction). Additionally, the edge positions of the segmented overlay or dummyfill subpattern in directions parallel and orthogonal to the measurement direction can be measured to determine the measurement bias induced in the direction of the segments.

There are various means (eg, hardware, software, and/or firmware) by which the processes and/or systems and/or other technologies described herein may be effected, with the preferred means being the process and/or system and/or other technologies. Those skilled in the art will understand that other techniques will vary depending on the context in which they are deployed. Program instructions implementing methods such as those described herein may be transmitted over or stored on a transmission medium. A transmission medium may include a transmission medium such as a wire, cable, or wireless transmission link. Transmission media may also include storage media such as read only memory, random access memory, magnetic or optical disks, or magnetic tape.

All methods described herein may include storing results of one or more steps of the method embodiments in a storage medium. Results may include any of the results described herein, and may be stored in any manner known in the art. The storage medium may include any storage medium described herein or any other suitable storage medium known in the art. After the results are stored, the results on the storage medium can be accessed, used by any of the method or system embodiments described herein, and can be formatted for display to a user. and may be used by other software modules, methods, or systems. Furthermore, results may be "permanent", "semi-permanent", "temporary" or stored for a period of time. For example, the storage medium may be random access memory (RAM), and results do not necessarily persist indefinitely on the storage medium.

Although specific embodiments of the present invention have been illustrated, it is apparent that various modifications and embodiments of the present invention can be made by those skilled in the art without departing from the spirit and scope of the foregoing disclosure. Accordingly, the scope of the present invention should be limited only by the claims appended hereto.

Claims (74)

In the overlay measurement tool,
An illumination source for illuminating an overlay target on a sample, the overlay target comprising:
A first layer target structure on the first layer of the sample, the first layer target structure comprising:
one or more first layer overlay regions comprising first layer overlay pattern elements; and
the first layer target structure including one or more first layer dummyfill regions proximate to one or more overlay pattern elements, the one or more first layer dummyfill regions comprising inactive dummyfill pattern elements; and
A second layer target structure on the second layer of the sample, the second layer target structure comprising one or more second layer overlay regions overlapping the first layer dummyfill region, the second layer overlay region comprising a first layer overlay region. comprising a second layer target structure comprising a two layer overlay pattern element;
a detector for generating imaging data associated with the overlay target in response to the illumination; and
a controller communicatively coupled to the detector, the controller including one or more processors comprising: the first layer overlay pattern elements and the second layer overlay identified using imaging data from the detector; and configured to execute program instructions that cause the one or more processors to determine an overlay error between the first layer and the second layer of the sample based on relative positions of pattern elements. The overlay metrology tool of claim 1 , wherein the first layer target structure and the second layer target structure are two-fold symmetric. The overlay metrology tool of claim 1 , wherein the first layer target structure and the second layer target structure are four-fold symmetric. The overlay metrology tool of claim 1 , wherein the second layer overlay pattern elements of the one or more second layer overlay regions are segmented. 5. The overlay metrology tool of claim 4, wherein the inactive dummyfill pattern elements of the one or more first layer overlay regions are periodic along a direction orthogonal to a segmentation direction of an overlapping portion of the second layer overlay region. 5. The overlay metrology tool of claim 4, wherein the inactive dummyfill pattern elements of the one or more first layer overlay regions are periodic along a direction parallel to a segmentation direction of an overlapping portion of the second layer overlay region. The overlay metrology tool of claim 1 , wherein the one or more second layer overlay pattern elements are unsegmented. The overlay metrology tool of claim 1 , wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented based on at least one of design rules or device dimensions. 2. The overlay metrology tool of claim 1, wherein the inactive dummyfill pattern elements of the one or more first layer dummyfill regions are segmented with a dimension that exceeds a minimum design rule. According to claim 1,
further comprising at least one second layer dummyfill region proximate to the at least one second layer overlay region and overlapping the first layer overlay region, wherein the second layer dummyfill region comprises an inactive dummyfill pattern element. In and overlay metrology tools. delete The overlay metrology tool of claim 1 , wherein the second layer is disposed on the first layer. The overlay metrology tool of claim 1 , wherein the first layer is disposed on the second layer. In the overlay target,
A first layer target structure on a first layer of a sample, the first layer target structure comprising:
one or more first layer overlay regions comprising first layer overlay pattern elements; and
the first layer target structure including one or more first layer dummyfill regions proximate to one or more overlay pattern elements, the one or more first layer dummyfill regions comprising inactive dummyfill pattern elements; and
a second layer target structure on a second layer of the sample, the second layer target structure including one or more second layer overlay regions overlapping the first layer dummyfill region, the second layer overlay region comprises a second layer overlay pattern element, wherein an overlay between the first layer and the second layer of the sample is determined based on the relative positions of the first layer overlay pattern element and the second layer overlay pattern element. , which is the overlay target. 15. The overlay target of claim 14, wherein the first layer target structure and the second layer target structure are two-fold symmetric. 15. The overlay target of claim 14, wherein the first layer target structure and the second layer target structure are 4-fold symmetric. 15. The overlay target of claim 14, wherein the second layer overlay pattern elements of the one or more second layer overlay regions are segmented. 18. The overlay target of claim 17, wherein the inactive dummyfill pattern elements of the at least one first-layer overlay region are periodic along a direction orthogonal to a segmentation direction of an overlapping portion of the second-layer overlay region. 18. The overlay target of claim 17, wherein the inactive dummyfill pattern elements of the at least one first-layer overlay region are periodic along a direction parallel to a segmentation direction of an overlapping portion of the second-layer overlay region. 15. The overlay target of claim 14, wherein the one or more second layer overlay pattern elements are unsegmented. 15. The overlay target of claim 14, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented based on at least one of design rules or device dimensions. 15. The overlay target of claim 14, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented with a dimension that exceeds a minimum design rule. According to claim 14,
further comprising at least one second layer dummyfill region proximate to the at least one second layer overlay region and overlapping the first layer overlay region, wherein the second layer dummyfill region comprises an inactive dummyfill pattern element. In, the overlay target. delete 15. The overlay target of claim 14, wherein the second layer is disposed on the first layer. 15. The overlay target of claim 14, wherein the first layer is disposed on the second layer. In the overlay measurement tool,
An illumination source for illuminating an overlay target on a sample, the overlay target comprising:
a first layer target structure on the first layer of the sample, the first layer target structure comprising at least one first layer overlay region comprising a first layer overlay pattern element;
a second layer target structure on a second layer of the sample, the second layer target structure comprising at least one second layer overlay region proximate to the first layer overlay region, the second layer overlay region comprising a second layer overlay region; the second layer target structure comprising an overlay pattern element; and
one or more dummy fill regions overlapping at least a portion of the one or more first layer overlay regions or the one or more second layer overlay regions;
a detector for generating imaging data associated with the overlay target in response to the illumination; and
a controller communicatively coupled to the detector, the controller including one or more processors comprising: the first layer overlay pattern elements and the second layer overlay identified using imaging data from the detector; and configured to execute program instructions that cause the one or more processors to determine an overlay error between the first layer and the second layer of the sample based on relative positions of pattern elements. 28. The overlay metrology tool of claim 27, wherein the first layer target structure and the second layer target structure are two-fold symmetric. 28. The overlay metrology tool of claim 27, wherein the first layer target structure and the second layer target structure are 4-fold symmetric. 28. The overlay metrology tool of claim 27, wherein the second layer overlay pattern elements of the one or more second layer overlay regions are segmented. 31. The overlay metrology tool of claim 30, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are periodic along a direction orthogonal to a segmentation direction of an overlapping portion of the second layer overlay region. 31. The overlay metrology tool of claim 30, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are periodic along a direction parallel to the segmentation direction of the overlapping portion of the second layer overlay region. 28. The overlay metrology tool of claim 27, wherein the first layer overlay pattern elements of the at least one first layer overlay region are segmented. 34. The overlay metrology tool of claim 33, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are periodic along a direction orthogonal to a segmentation direction of an overlapping portion of the first layer overlay region. 34. The overlay metrology tool of claim 33, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are periodic along a direction parallel to the segmentation direction of the overlapping portion of the first layer overlay region. The method of claim 27,
wherein the inactive dummyfill pattern elements of the one or more first layer dummyfill regions are segmented based on at least one of design rules or device dimensions. The method of claim 27,
wherein the inactive dummyfill pattern elements of the one or more first layer dummyfill regions are segmented with a dimension exceeding a minimum design rule. 28. The overlay metrology tool of claim 27, wherein the second layer is disposed on the first layer. 28. The overlay metrology tool of claim 27, wherein the first layer is disposed on the second layer. delete In the overlay measurement tool,
An illumination source for illuminating an overlay target on a sample, the overlay target comprising:
A first layer target structure on a first layer of a sample, the first layer target structure comprising one or more first layer dummyfill regions comprising an inactive dummyfill pattern element, each of the one or more first layer dummyfill regions wherein the first layer target structure comprises an aperture having an inner edge enabling localization of the aperture; and
a second layer target structure on the second layer of the sample, the second layer target structure comprising one or more second layer overlay pattern elements overlapping the one or more first layer dummyfill regions and positioned proximate one or more openings; comprising the second layer target structure comprising;
a detector for generating imaging data associated with the overlay target in response to the illumination; and
a controller communicatively coupled to the detector, the controller including one or more processors comprising: the second layer overlay pattern elements identified using the imaging data from the detector and the first layer overlay pattern elements; and configured to execute program instructions that cause the one or more processors to determine an overlay error between the first layer and the second layer of the sample based on the relative position of the dummyfill region. 42. The overlay metrology tool of claim 41, wherein the first layer target structure and the second layer target structure are two-fold symmetric. 42. The overlay metrology tool of claim 41, wherein the first layer target structure and the second layer target structure are 4-fold symmetric. 42. The overlay metrology tool of claim 41, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented based on at least one of design rules or device dimensions. 42. The overlay metrology tool of claim 41, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented with a dimension that exceeds a minimum design rule. 42. The overlay metrology tool of claim 41, wherein the second layer is disposed on the first layer. 42. The overlay metrology tool of claim 41, wherein the first layer is disposed on the second layer. In the overlay measurement tool,
An illumination source for illuminating an overlay target on a sample, the overlay target comprising:
a first layer target structure on a first layer of a sample, the first layer target structure comprising at least one first layer dummyfill region comprising an inactive dummyfill pattern element; and
a second layer target structure on a second layer of the sample, the second layer target structure overlapping the one or more first layer dummyfill regions associated with a first exposure on the second layer of the sample; a first set of second layer overlay pattern elements, the second layer target structure of the sample, without an exclusion zone between the first and second sets of second layer overlay pattern elements. comprising said second set of second layer overlay pattern elements overlapping said one or more first layer dummyfill regions associated with a second exposure of a second layer;
a detector for generating imaging data associated with the overlay target in response to the illumination; and
a controller communicatively coupled to the detector, the controller including one or more processors comprising: the second layer overlay pattern elements identified using the imaging data from the detector and the first layer overlay pattern elements; and configured to execute program instructions that cause the one or more processors to determine an overlay error between the first layer and the second layer of the sample based on the relative position of the dummyfill region. 49. The overlay metrology tool of claim 48, wherein the first layer target structure and the second layer target structure are two-fold symmetric. 49. The overlay metrology tool of claim 48, wherein the first layer target structure and the second layer target structure are 4-fold symmetric. 49. The overlay metrology tool of claim 48, wherein the first set and the second set of second layer overlay pattern elements are segmented. 52. The method of claim 51, wherein the inactive dummyfill pattern elements of the one or more first layer dummyfill regions are directed in a direction orthogonal to a segmentation direction of overlapping portions of the first set and the second set of second layer overlay pattern elements. Follow the periodic, overlay instrumentation tool. 52. The method of claim 51 wherein said inactive dummyfill pattern elements of said at least one first layer dummyfill region are directed in a direction parallel to a segmentation direction of overlapping portions of said first set and said second set of second layer overlay pattern elements. Follow the periodic, overlay instrumentation tool. 49. The overlay metrology tool of claim 48, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented based on at least one of design rules or device dimensions. 49. The overlay metrology tool of claim 48, wherein the inactive dummyfill pattern elements of the one or more first-layer dummyfill regions are segmented to a dimension that exceeds a minimum design rule. 49. The overlay metrology tool of claim 48, wherein the first set and the second set of second layer overlay pattern elements are aligned according to a lithographic overlay tolerance. 49. The overlay metrology tool of claim 48, wherein the second layer is disposed on the first layer. 49. The overlay metrology tool of claim 48, wherein the first layer is disposed on the second layer. In the overlay measurement tool,
An illumination source for illuminating an overlay target on a sample, the overlay target comprising:
a first layer target structure on a first layer of a sample, the first layer target structure comprising at least one first layer overlay region having a first layer overlay pattern element;
a second layer target structure on the second layer of the sample, the second layer target structure comprising one or more second layer overlay regions having second layer overlay pattern elements, the one or more second layer overlay regions comprising: the second layer target structure overlapping at least one first layer overlay region; and
one or more dummy fill regions having periodic inactive dummy fill pattern elements, the dummy fill regions overlapping the first layer overlay region and the second layer overlay region, and the first layer overlay pattern within the overlapping region; element and the second layer overlay pattern elements are periodic along a common direction orthogonal to the direction of periodicity of the inactive dummy fill pattern elements in the overlapping region;
a detector for capturing light from the overlay target in response to the illumination; and
a controller communicatively coupled to the detector, wherein the controller includes one or more processors configured to: Based on the relative positions of the first layer overlay pattern elements and the second layer overlay pattern elements identified using data from the detector, the one or more processors determine the overlay between the first layer and the second layer of the sample. An overlay metrology tool, comprising: configured to execute program instructions that cause an error to be determined. 60. The overlay metrology tool of claim 59, wherein at least one of pitch or spacing of the first layer overlay pattern elements and the second layer overlay pattern elements are the same. 60. The overlay metrology tool of claim 59, wherein at least one of pitch or spacing of the first layer overlay pattern elements and the second layer overlay pattern elements are different. 60. The overlay metrology tool of claim 59, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are segmented based on at least one of design rules or device dimensions. 60. The overlay metrology tool of claim 59, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are segmented with a dimension that exceeds a minimum design rule. 60. The overlay metrology tool of claim 59, wherein the second layer is disposed on the first layer. 60. The overlay metrology tool of claim 59, wherein the first layer is disposed on the second layer. delete In the diffraction-based overlay target,
a first layer target structure on a first layer of a sample, the first layer target structure comprising at least one first layer overlay region having a first layer overlay pattern element;
a second layer target structure on the second layer of the sample, the second layer target structure comprising one or more second layer overlay regions having second layer overlay pattern elements, the one or more second layer overlay regions comprising: the second layer target structure overlapping at least one first layer overlay region; and
one or more dummy fill regions having periodic inactive dummy fill pattern elements, the dummy fill regions overlapping the first layer overlay region and the second layer overlay region, and the first layer overlay pattern within the overlapping region; element and the second layer overlay pattern elements are periodic along a common direction orthogonal to the direction of periodicity of the inactive dummyfill pattern elements in the overlapping region, the overlay between the first layer and the second layer of the sample. wherein the error is determined based on the relative positions of the first layer overlay pattern elements and the second layer overlay pattern elements identified by the diffraction of light from the first layer overlay pattern elements and the second layer overlay pattern elements. , a diffraction-based overlay target. 68. The diffraction-based overlay target of claim 67, wherein at least one of a pitch or spacing of the first layer overlay pattern elements and the second layer overlay pattern elements is the same. 68. The diffraction-based overlay target of claim 67, wherein at least one of pitch or spacing of the first layer overlay pattern elements and the second layer overlay pattern elements are different. 68. The diffraction-based overlay target of claim 67, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are segmented based on at least one of design rules or device dimensions. 68. The diffraction-based overlay target of claim 67, wherein the inactive dummyfill pattern elements of the one or more dummyfill regions are segmented with a dimension exceeding a minimum design rule. 68. The diffraction-based overlay target of claim 67, wherein the second layer is disposed on the first layer. 68. The diffraction-based overlay target of claim 67, wherein the first layer is disposed on the second layer.


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