Critical dimension testing structure and measuring method thereof

Abstract

The embodiment of the invention relates to a critical dimension testing structure and a measuring method thereof. The test structure comprises a plurality of functional areas located in a target layer, the plurality of functional areas comprise: a positioning area comprising a positioning pattern, the geometric center of the positioning pattern coinciding with the geometric center of the positioning area; the first pattern area comprises a plurality of sub-patterns with critical dimensions, and the density of the sub-patterns in the first pattern area is equal to the density of the patterns with the critical dimensions in the product area; wherein the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the first direction is a first preset value, the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the second direction is a second preset value, and the second direction intersects with the first direction. And the shape and the extension direction of the sub-pattern are not influenced by the critical dimension test structure, so that the influence of the external environment on the measurement of the critical dimension is eliminated.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor technology, and in particular to a critical dimension test structure and a measurement method thereof. Background Art

[0002] In the process of preparing DRAM (Dynamic Random Access Memory), the size of the key dimensions, pitch, type of graphics (Line, Space, Hole, Pillar) and extension direction of each layer of graphics that need to be measured are different, which poses a great challenge to the design and measurement of key graphic measurement marks.

[0003] A typical key graphic measurement mark is an L-shaped graphic. This graphic has many blank areas and occupies a large area (40um*40um). It can only be placed in the scribe line area and can only be used to measure graphics in the horizontal and vertical directions. It is greatly affected by the process and cannot truly reflect the performance of key graphics in the product area. Sometimes it is necessary to directly measure the graphics in the product area, which not only destroys the graphics in the product area, but also makes the creation of the measurement program relatively complex and random. How to obtain the performance of the graphics in the product area by marking the graphics has become an urgent problem to be solved. Summary of the invention

[0004] The embodiments of the present application provide a critical dimension test structure and a measurement method thereof.

[0005] A critical dimension test structure includes a plurality of functional areas located in a target layer, wherein the plurality of functional areas include:

[0006] The positioning area includes a positioning pattern, wherein the geometric center of the positioning pattern coincides with the geometric center of the positioning area;

[0007] A first graphic area includes a plurality of sub-graphics having a critical size, wherein a density of the sub-graphics in the first graphic area is equal to a density of the critical size graphics in the product area;

[0008] Among them, the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the first direction is a first preset value, and the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the second direction is a second preset value, and the second direction intersects with the first direction.

[0009] In one embodiment, the plurality of functional areas further include:

[0010] The identification area corresponds one-to-one to the positioning area and the first graphic area.

[0011] In one embodiment, the first graphic area is a dense graphic area; the plurality of functional areas further include:

[0012] A sparse pattern area, including a reference pattern with the same critical dimensions as the sub-pattern;

[0013] Among them, the distance between the geometric center of the positioning area and the geometric center of the test area in the sparse graphic area in the first direction is a third preset value, and the distance between the geometric center of the positioning area and the geometric center of the test area in the sparse graphic area in the second direction is a fourth preset value.

[0014] In one embodiment, the dense graphic area includes: a first dense graphic area and a second dense graphic area arranged adjacent to each other in a first direction, and the sparse graphic area includes: a first sparse graphic area and a second sparse graphic area arranged adjacent to each other in a second direction;

[0015] The plurality of sub-patterns include a plurality of first sub-patterns arrayed in a first dense pattern area and a plurality of second sub-patterns arrayed in a second dense pattern area; the reference pattern includes a first reference pattern located in a first sparse pattern area and a second reference pattern located in a second sparse pattern area, the first reference pattern and the first sub-pattern are of the same type and have the same extension direction, and the second reference pattern and the second sub-pattern are of the same type and have the same extension direction;

[0016] The first sub-graph and the second sub-graph are linear graphs with different extension directions respectively;

[0017] Or, the first sub-pattern and the second sub-pattern are groove-shaped patterns with different extending directions;

[0018] Or, the first sub-pattern and the second sub-pattern are respectively hole-shaped patterns with different radial directions;

[0019] Alternatively, the first sub-graph and the second sub-graph are columnar graphs with different radial directions.

[0020] In one embodiment, the positioning area and the sparse graphic area are arranged adjacent to each other, the first graphic area is arranged on the same side of the positioning area and the sparse graphic area, and the plurality of functional areas are arranged in a square shape; the area of ​​the square is less than or equal to 100 μm 2 , and the sizes of the first dense graphic area and the second dense graphic area are both greater than or equal to 5um*5um.

[0021] In one embodiment, the test area in the first graphic area includes a first test area and a second test area, and the test area in the sparse graphic area includes a third test area and a fourth test area;

[0022] Among them, the geometric center of the first dense graphic area coincides with the geometric center of the first test area, the geometric center of the second dense graphic area coincides with the geometric center of the second test area, the geometric center of the first sparse graphic area coincides with the geometric center of the third test area, and the geometric center of the second sparse graphic area coincides with the geometric center of the fourth test area.

[0023] In one embodiment, the first sub-pattern and the second sub-pattern are both line-shaped patterns or both groove-shaped patterns; wherein,

[0024] The ends of the first sub-pattern located at the geometric center of the first dense pattern area are all provided with a first marking pattern;

[0025] The ends of the second sub-pattern located at the geometric center of the second dense pattern area are all provided with second marking patterns.

[0026] In one embodiment, the first sub-pattern and the second sub-pattern are both hole-shaped patterns or both column-shaped patterns; wherein,

[0027] A third marking pattern is arranged at the end of the central row and / or the central column of the first dense pattern area;

[0028] The end of the central row and / or central column of the second dense pattern area is provided with a fourth marking pattern.

[0029] In one of the embodiments, different target layers are stacked in the third direction, and orthographic projections of functional areas in different target layers on the horizontal plane do not overlap;

[0030] The third direction is perpendicular to a horizontal plane where the first direction and the second direction intersect.

[0031] The present disclosure also provides a method for measuring a critical dimension test structure, comprising:

[0032] Providing a substrate, on which the critical dimension test structure as described above is formed;

[0033] Positioning the critical dimension test structure according to the coordinate information of the geometric center of the positioning area;

[0034] The position of the sub-pattern is confirmed according to the corresponding relationship between the geometric center of the positioning area and the geometric center of the test area in the first pattern area, and the key size of the sub-pattern is measured.

[0035] In one embodiment, positioning the critical dimension test structure according to the coordinate information of the geometric center of the positioning area includes:

[0036] Coarsely locate the critical size test structure according to the coordinate information of the geometric center of the positioning area;

[0037] The critical dimension test structure is precisely positioned according to the geometric center of the positioning pattern.

[0038] The above-mentioned critical dimension test structure can be positioned to the geometric center of the test area in the first graphic area according to the geometric center of the positioning area, that is, to the position of the sub-graphic, so as to test and obtain the critical dimension of the critical dimension graphic. The shape and extension direction of the sub-graphic are not affected by the critical dimension test structure. The density of the sub-graphic in the first graphic area is equal to the density of the critical dimension graphic in the product area, eliminating the influence of the external environment on the critical dimension measurement.

[0039] The measurement method of the above-mentioned critical dimension test structure can locate the geometric center of the test area in the first graphic area through the coordinate information of the geometric center of the positioning area, that is, locate the position of the sub-graphic, so as to test and obtain the critical dimension of the critical dimension graphic. The shape and extension direction of the sub-graphic are not affected by the critical dimension test structure. The density of the sub-graphic in the first graphic area is equal to the density of the critical dimension graphic in the product area, eliminating the influence of the external environment on the critical dimension measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of a top view of a critical dimension test structure in an embodiment;

[0042] Figure 2 is a top view schematic diagram of the critical dimension test structure in the first embodiment;

[0043] Figure 3 is a schematic top view of a critical dimension test structure in the second embodiment;

[0044] Figure 4 is a top view schematic diagram of a critical dimension test structure in the third embodiment;

[0045] Figure 5 Schematic diagram of a process for testing a critical dimension test structure in one embodiment.

[0046] Description of reference numerals:

[0047] 100, critical dimension test structure; 102, positioning area; 104, first graphic area; 106, identification area; 108, sparse graphic area; 202, positioning pattern; 204, first dense graphic area; 206, second dense graphic area; 208, first sparse graphic area; 210, second sparse graphic area; 302, first sub-pattern; 304, second sub-pattern; 306, first reference pattern; 308, second reference pattern; 310, first gap pattern; 312, second gap pattern; 314, first dense graphic area geometric center; 316, first marking pattern; 318, second dense graphic area geometric center; 320, second marking pattern; 322, first test area; 324, second test area; 326, third test area; 328, fourth test area; 330, first sparse graphic area geometric center; 332, second sparse graphic area geometric center; 334, third marking pattern; 336, fourth marking pattern. DETAILED DESCRIPTION

[0048] In order to facilitate understanding of the embodiments of the present application, the embodiments of the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the embodiments of the present application are given in the drawings. However, the embodiments of the present application can be implemented in many different forms and are not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the embodiments of the present application more thorough and comprehensive.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the embodiments of the present application. The terms used herein in the specification of the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0050] In the description of the embodiments of the present application, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the methods or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0051] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first dense graphic area may be referred to as a second dense graphic area, and similarly, a second dense graphic area may be referred to as a first dense graphic area. Both the first dense graphic area and the second dense graphic area are dense graphic areas, but they are not the same dense graphic area.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0053] Figure 1 FIG. 1 is a schematic diagram of a top view of a critical dimension test structure in an embodiment. Figure 1 As shown, in this embodiment, a critical dimension test structure 100 is provided, comprising a plurality of functional areas located in a target layer, wherein the plurality of functional areas include: a positioning area 102 and a first graphic area 104; the positioning area 102 includes a positioning graphic 202, the geometric center of the positioning graphic 202 coincides with the geometric center of the positioning area 102; the first graphic area 104 includes a plurality of sub-graphics having a critical dimension, the density of the sub-graphics in the first graphic area 104 is equal to the density of the critical dimension graphics in the product area; wherein the distance between the geometric center of the positioning area 102 and the geometric center of the test area in the first graphic area 104 in the first direction X is a first preset value, and the distance between the geometric center of the positioning area 102 and the geometric center of the test area in the first graphic area 104 in the second direction Y is a second preset value, and the second direction X intersects the first direction Y. Exemplarily, the first direction X is perpendicular to the second direction Y.

[0054] Specifically, the target layer is a functional layer where a critical dimension pattern with a critical dimension is located; the positioning pattern 202 is a pattern whose geometric center set in the positioning area 102 coincides with the geometric center of the positioning area 102; the shape of the positioning pattern 202 includes but is not limited to a cross, a polygon, a circle or an ellipse. The sub-pattern is a pattern formed in the first pattern area 104 for measuring the critical dimension of the critical dimension pattern formed in the product area. The sub-pattern can be exactly the same as the shape of the critical dimension pattern, or it can be the same as the shape of a part of the critical dimension pattern. The first pattern area 104 is a separate area, so the shape and extension direction of the sub-pattern are not affected by the critical dimension test structure; the critical dimension pattern is a pattern formed in the target layer that needs to be paid attention to whether the size is abnormal. The product area is the area on the substrate where the device including the critical dimension pattern is located; the test area here is the area in the first pattern area 104 where the critical dimension is tested. The density of the sub-pattern in the first pattern area 104 is equal to the density of the critical dimension pattern in the product area, so that the sub-pattern and the critical dimension pattern are subject to the same focal length influence and the same energy during the exposure and development process, and the measurement value of the critical dimension obtained by measuring the sub-pattern is closer to the actual value of the critical dimension of the critical dimension pattern.

[0055] The above-mentioned critical dimension test structure can be positioned to the geometric center of the test area in the first graphic area 104 according to the geometric center of the positioning area 102, that is, to the position of the sub-graphic, so as to test and obtain the critical dimension of the critical dimension graphic. The shape and extension direction of the sub-graphic are not affected by the critical dimension test structure. The density of the sub-graphic in the first graphic area 104 is equal to the density of the critical dimension graphic in the product area, eliminating the influence of the external environment on the critical dimension measurement.

[0056] Continue to refer Figure 1 In one embodiment, the multiple functional areas also include: an identification area 106, and the identification area 106 corresponds one-to-one with the positioning area 102 and the first graphic area 104. The mark formed in the identification area 106 can be used as a graphic registration mark of a critical dimension test structure. When multiple critical dimension test structures are set in the same target layer, the location of the critical dimension test structure that needs to be measured can be accurately distinguished through the identification area 106. Optionally, the identification area 106 includes a digital mark and / or a letter mark. Exemplarily, the mark is set in the central area of ​​the identification area 106. The size and position of the mark formed in the marking area 106 must not interfere with the critical dimension graphic, the positioning graphic 202 and the sub-graphic.

[0057] Continue to refer Figure 1In one embodiment, the first graphic area 104 is a dense graphic area; at this time, the sub-graphic located in the test area of ​​the first graphic area 104 can reflect the influence of energy on the critical dimension graphic during the exposure and development process; the multiple functional areas also include: a sparse graphic area 108, including a reference graphic with the same critical dimension as the sub-graphic; the reference graphic here can be the same shape and size as the critical dimension graphic, or different, as long as it can reflect the size of the critical dimension in the critical dimension graphic. Among them, the distance between the geometric center of the positioning area 102 and the geometric center of the test area in the sparse graphic area 108 in the first direction X is a third preset value, and the distance between the geometric center of the positioning area 102 and the geometric center of the test area in the sparse graphic area 108 in the second direction Y is a fourth preset value. The reference graphic located in the test area of ​​the sparse graphic area 108 can reflect the influence of the focal length on the critical dimension graphic during the exposure and development process; when the test values ​​of the critical dimension obtained by measuring the sub-graphic and the reference graphic are both within the control range of the critical dimension, it is determined that the critical dimension graphic meets the process requirements.

[0058] Figure 2 is a top view schematic diagram of the key dimension test structure in the first embodiment, Figure 3 FIG. 1 is a top view of a critical dimension test structure in the second embodiment. Figure 1 , Figure 2 , Figure 3 As shown, in this embodiment, the first graphic area 104 (dense graphic area) includes: a first dense graphic area 204 and a second dense graphic area 206 arranged adjacent to each other in the first direction X, and the sparse graphic area 108 includes: a first sparse graphic area 208 and a second sparse graphic area 210 arranged adjacent to each other in the second direction Y; the multiple sub-graphics include a plurality of first sub-graphics 302 distributed in an array in the first dense graphic area 204 and a plurality of second sub-graphics 304 distributed in an array in the second dense graphic area 206; the reference graphic includes a first reference graphic 306 located in the first sparse graphic area 208 and a second reference graphic 308 located in the second sparse graphic area 210, the first reference graphic 306 and the first sub-graphic 302 are of the same type and have an extension direction, and the second reference graphic 308 and the second sub-graphic 304 are of the same type and have an extension direction.

[0059] Exemplarily, a first sub-graphic 302 and a first gap graphic 310 located between adjacent first sub-graphics 302 or on one side of adjacent first sub-graphics 302 are obtained by patterning the target material layer in the first dense graphic area 204; a second sub-graphic 304 and a second gap graphic 312 located between adjacent second sub-graphics 304 or on one side of adjacent second sub-graphics 304 are obtained by patterning the target material layer in the second dense graphic area 206, and the target layer is obtained after patterning the target material layer.

[0060] like Figure 2 As shown, when the first sub-graph 302 is a bar pattern formed by the remaining target material layer, extending along the third direction M and arranged at intervals in the vertical direction of the third direction M, and the second sub-graph 304 is a bar pattern formed by the remaining target material layer, extending along the fourth direction N and arranged at intervals in the vertical direction of the fourth direction N, the first sub-graph 302 and the second sub-graph 304 are line-shaped (line) graphs with different extension directions, wherein the fourth direction N intersects the third direction M. Exemplarily, the fourth direction N is perpendicular to the third direction M. When the first sub-graph 302 is a bar pattern extending along the third direction M and arranged at intervals in the vertical direction of the third direction M obtained after removing the target material layer, and the second sub-graph 304 is a bar pattern extending along the fourth direction N and arranged at intervals in the vertical direction of the fourth direction N obtained after removing the target material layer, the first sub-graph 302 and the second sub-graph 304 are groove-shaped (space) graphs with different extension directions. It can be understood that the third direction M can be parallel to the second direction Y, can be perpendicular to the second direction Y, or can intersect with the second direction Y; the fourth direction N can be parallel to the first direction X, can be perpendicular to the first direction X, or can intersect with the first direction X. By measuring the critical dimensions of the first sub-pattern 302 and the second sub-pattern 304 extending in the intersecting direction, it can be known whether there is an abnormality in the phase difference of the photolithography machine (scanner) during exposure.

[0061] like Figure 3 As shown, when the first sub-graphic 302 is a circular pattern, an elliptical pattern or a line segment pattern extending along the third direction M obtained after removing the target material layer, and is arranged at intervals in the third direction M and in a direction perpendicular to the third direction M, and the second sub-graphic 304 is a circular pattern, an elliptical pattern or a line segment pattern extending along the fourth direction N obtained after removing the target material layer, and is arranged at intervals in the fourth direction N and in a direction perpendicular to the fourth direction N, the first sub-graphic 302 and the second sub-graphic 304 are respectively hole-shaped graphics with different radial directions. When the first sub-graph 302 is a circular pattern, an elliptical pattern or a line segment pattern formed by the remaining target material layer, extending along the third direction M, and arranged at intervals in the third direction M and in a direction perpendicular to the third direction M, and the second sub-graph 304 is a circular pattern, an elliptical pattern or a line segment pattern formed by the remaining target material layer, extending along the fourth direction N, and arranged at intervals in the fourth direction N and in a direction perpendicular to the fourth direction N, the first sub-graph 302 and the second sub-graph 304 are respectively pillar patterns with different radial directions. Figure 3 The third direction M is parallel to the second direction Y, and the fourth direction N is parallel to the first direction X for exemplary description.

[0062] Continue to refer Figure 2 In one embodiment, the first sub-graph 302 and the second sub-graph 304 are both linear graphs or groove graphs; wherein the ends of the first sub-graph 302 located at the geometric center 314 of the first dense graph area are both provided with a first marking graph 316; and the ends of the second sub-graph 304 located at the geometric center 318 of the second dense graph area are both provided with a second marking graph 320.

[0063] Optionally, when the first sub-pattern 302 and the second sub-pattern 304 are both linear patterns, the top surface of the first mark pattern 316 may be higher than the top surface of the first gap pattern 310. When the first mark pattern 316 contacts the first sub-pattern 302, the constituent material of the first mark pattern 316 is different from the constituent material of the target material layer, so as to distinguish the first mark pattern 316 from the first sub-pattern 302. The top surface of the first mark pattern 316 may also be flush with the top surface of the first gap pattern 310 (i.e., the first mark pattern 316 is a groove). In this case, the first mark pattern 316 may be used as a part of the first gap pattern 310. By setting the first mark pattern 316, the first sub-pattern 302 located at the geometric center 314 of the first dense pattern area can be quickly found. The top surface of the second mark pattern 320 may be higher than the top surface of the second gap pattern 312. When the second mark pattern 320 contacts the second sub-pattern 304, the constituent material of the second mark pattern 320 is different from the constituent material of the target material layer, so as to distinguish the second mark pattern 320 from the second sub-pattern 304. The top surface of the second mark pattern 320 may also be flush with the top surface of the second gap pattern 312 (i.e., the second mark pattern 320 is a groove). In this case, the second mark pattern 320 may be used as a part of the second gap pattern 312. By setting the second mark pattern 320, the second sub-pattern 304 located at the geometric center 318 of the second set pattern area can be quickly found. Among them, the top surface of the second mark pattern 320 may be flush with the top surface of the first mark pattern 316, or may be different from the top surface of the first mark pattern 316. The constituent material of the second mark pattern 320 may be the same as the constituent material of the first mark pattern 316, or may be different from the constituent material of the first mark pattern 316.

[0064] Optionally, when both the first sub-pattern 302 and the second sub-pattern 304 are groove-shaped patterns, the top surface of the first mark pattern 316 may be higher than the top surface of the first sub-pattern 302, the constituent material of the first mark pattern 316 and the constituent material of the target material layer may be the same or different, and the top surface of the first mark pattern 316 may also be flush with the top surface of the first gap pattern 310 (i.e., the first mark pattern 316 is a stripe structure), and in this case, the first mark pattern 316 may be used as a part of the first gap pattern 310. The top surface of the first mark pattern 316 may be flush with the top surface of the first sub-pattern 302, and in this case, the first mark pattern 316 is spaced apart from the first sub-pattern 302, so as to distinguish the first mark pattern 316 from the first sub-pattern 302. By setting the first mark pattern 316, the first sub-pattern 302 located at the geometric center 314 of the first dense pattern area can be quickly found. The top surface of the second mark pattern 320 may be higher than the top surface of the second sub-pattern 304. The constituent material of the second mark pattern 320 and the constituent material of the target material layer may be the same or different. The top surface of the second mark pattern 320 may also be flush with the top surface of the second gap pattern 312 (i.e., the second mark pattern 320 is a stripe structure). In this case, the second mark pattern 320 may be used as a part of the second gap pattern 312. The top surface of the second mark pattern 320 may also be flush with the top surface of the first sub-pattern 302. In this case, the second mark pattern 320 is spaced apart from the second sub-pattern 304 to distinguish the second mark pattern 320 from the second sub-pattern 304. By setting the second mark pattern 320, the second sub-pattern 304 located at the geometric center 318 of the second dense pattern area may be quickly found.

[0065] It can be understood that the test area in the first graphic area 104 includes a first test area 322 in the first dense graphic area 204 and a second test area 324 in the second dense graphic area 206. Exemplarily, the first test area 322 is centered on the geometric center 314 of the first dense graphic area, that is, the geometric center of the first dense graphic area 204 coincides with the geometric center of the first test area 322. Exemplarily, one of the two intersecting sides of the first test area 322 is parallel to the extension direction of the first sub-graphic 302, and the other side is perpendicular to the extension direction of the first sub-graphic 302. The first test area 322 includes a partial area of ​​the first sub-graphic 302 located at the geometric center 314 of the first dense graphic area and partial areas of several first sub-graphics 302 adjacent to the first sub-graphics 302 located at the geometric center 314 of the first dense graphic area. By measuring the first sub-graphic 302 located at the geometric center 314 of the first dense graphic area, a test value closer to the true value of the critical dimension of the critical dimension graphic after being affected by the exposure and development energy can be obtained. Exemplarily, the number of first sub-graphs 302 in the first test area 322 is an odd number. Optionally, the second test area 324 is centered on the second dense pattern area geometric center 318, that is, the geometric center of the second dense pattern area 206 coincides with the geometric center of the second test area 324, and the second test area 324 is similar to the first test area 322. The distances between the geometric center of the positioning area 102 and the geometric center 314 of the first dense pattern area, and between the geometric center of the positioning area 102 and the geometric center 318 of the second dense pattern area in the first direction X and the second direction Y are all constant values. Therefore, the geometric center of the first dense pattern area 314 and the geometric center of the second dense pattern area 318 can be located according to the geometric center of the positioning area 102, and then the first sub-graph 302 located at the geometric center 314 of the first dense pattern area and the second sub-graph 304 located at the geometric center 318 of the second dense pattern area can be quickly found.

[0066] Optionally, the test area in the sparse pattern area 108 includes a third test area 326 in the first sparse pattern area 208 and a fourth test area 328 in the second sparse pattern area 210. Exemplarily, the third test area 326 is centered on the geometric center 330 of the first sparse pattern area, that is, the geometric center of the first sparse pattern area 208 coincides with the geometric center of the third test area 326. Exemplarily, one of the two intersecting sides of the third test area 326 is parallel to the extension direction of the first reference pattern 306, and the other side is perpendicular to the extension direction of the first reference pattern 306. The third test area 326 includes a partial area of ​​the first reference pattern 306 located at the geometric center 330 of the first sparse pattern area. By measuring the first reference pattern 306 located at the geometric center 330 of the first sparse pattern area, a test value closer to the true value of the key dimension of the key dimension pattern affected by the exposure and development focus can be obtained. Optionally, the fourth test area 328 is centered on the second sparse pattern area geometric center 332, that is, the geometric center of the second sparse pattern area 210 coincides with the geometric center of the fourth test area 328, and the fourth test area 328 is similar to the third test area 326. The distances between the geometric center of the positioning area 102 and the geometric center of the first sparse pattern area 330, and between the geometric center of the positioning area 102 and the geometric center of the second sparse pattern area 332 in the first direction X and the second direction Y are all constant values. Therefore, the geometric center of the first sparse pattern area 330 and the geometric center of the second sparse pattern area 332 can be located according to the geometric center of the positioning area 102, and then the first reference pattern 306 and the second reference pattern 308 can be quickly found.

[0067] like Figure 3 As shown, in one embodiment, the first sub-graphic 302 and the second sub-graphic 304 are both hole-shaped graphics or both column-shaped graphics; wherein, the third marking graphic 334 is arranged at the end of the center row and / or center column of the first dense graphic area 204; and the fourth marking graphic 336 is arranged at the end of the center row and / or center column of the second dense graphic area 206.

[0068] Optionally, in the third direction M (row direction of the first dense graphic area 204), the interval between adjacent first sub-graphics 302 is a first distance, and in the vertical direction of the third direction M (column direction of the first dense graphic area 204), the interval between adjacent first sub-graphics 302 is a second distance, wherein the first distance and the second distance may be equal or unequal. In the fourth direction N (row direction of the second dense graphic area 206), the interval between adjacent second sub-graphics 304 is a third distance, and in the vertical direction of the fourth direction N (column direction of the second dense graphic area 206), the interval between adjacent second sub-graphics 304 is a fourth distance, wherein the third distance and the fourth distance may be equal or unequal. It can be understood that the first distance is equal to the third distance, and the second distance is equal to the fourth distance.

[0069] Optionally, when the first sub-pattern 302 and the second sub-pattern 304 are both hole-shaped patterns, the top surface of the third mark pattern 334 may be higher than the top surface of the first sub-pattern 302, the constituent material of the third mark pattern 334 and the constituent material of the target material layer may be the same or different, and the top surface of the third mark pattern 334 may also be flush with the top surface of the first gap pattern 310 (i.e., the third mark pattern 334 is a columnar structure), and in this case, the third mark pattern 334 may be used as a part of the first gap pattern 310. The top surface of the third mark pattern 334 may be flush with the top surface of the first sub-pattern 302, and in this case, the third mark pattern 334 is spaced apart from the first sub-pattern 302, so as to distinguish the third mark pattern 334 from the first sub-pattern 302. By setting the third mark pattern 334, the first sub-pattern 302 located at the geometric center 314 of the first dense pattern area can be quickly found. The top surface of the fourth mark pattern 336 may be higher than the top surface of the second sub-pattern 304. The constituent material of the fourth mark pattern 336 and the constituent material of the target material layer may be the same or different. The top surface of the fourth mark pattern 336 may also be flush with the top surface of the second gap pattern 312 (i.e., the fourth mark pattern 336 is a columnar structure). In this case, the fourth mark pattern 336 may be used as a part of the second gap pattern 312. The top surface of the fourth mark pattern 336 may also be flush with the top surface of the first sub-pattern 302. In this case, the fourth mark pattern 336 is spaced apart from the second sub-pattern 304 to distinguish the fourth mark pattern 336 from the second sub-pattern 304. By setting the fourth mark pattern 336, the second sub-pattern 304 located at the geometric center 318 of the second dense pattern area may be quickly found.

[0070] Optionally, when both the first sub-pattern 302 and the second sub-pattern 304 are columnar patterns, the top surface of the third mark pattern 334 may be higher than the top surface of the first gap pattern 310. When the third mark pattern 334 contacts the first sub-pattern 302, the constituent material of the third mark pattern 334 is different from the constituent material of the target material layer, so as to distinguish the third mark pattern 334 from the first sub-pattern 302. The top surface of the third mark pattern 334 may also be flush with the top surface of the first gap pattern 310 (i.e., the third mark pattern 334 is a groove), and in this case, the third mark pattern 334 may be used as a part of the first gap pattern 310. By setting the third mark pattern 334, the first sub-pattern 302 located at the geometric center 314 of the first dense pattern area can be quickly found. The top surface of the fourth mark pattern 336 may be higher than the top surface of the second gap pattern 312. When the fourth mark pattern 336 contacts the second sub-pattern 304, the constituent material of the fourth mark pattern 336 is different from the constituent material of the target material layer, thereby distinguishing the fourth mark pattern 336 from the second sub-pattern 304. The top surface of the fourth mark pattern 336 may also be flush with the top surface of the second gap pattern 312 (i.e., the fourth mark pattern 336 is a groove). In this case, the fourth mark pattern 336 may be used as a part of the second gap pattern 312. By setting the fourth mark pattern 336, the second sub-pattern 304 located at the geometric center 318 of the second set pattern area can be quickly found. Among them, the top surface of the fourth mark pattern 336 may be flush with the top surface of the third mark pattern 334, or may be different from the top surface of the third mark pattern 334. The constituent material of the fourth mark pattern 336 may be the same as the constituent material of the third mark pattern 334, or may be different from the constituent material of the third mark pattern 334.

[0071] Continue to refer Figure 1 In one embodiment, the positioning area 102 and the sparse graphic area 108 are arranged adjacent to each other, the first graphic area 104 is arranged on the same side of the positioning area 102 and the sparse graphic area 108, and the plurality of functional areas are arranged in a square shape; the area of ​​the square is less than or equal to 100 μm 2 , and the sizes of the first dense pattern area 204 and the second dense pattern area 206 are both greater than or equal to 5um*5um. When the sizes of the first dense pattern area 204 and the second dense pattern area 206 are equal to 5um*5um, the distribution of the sub-patterns is the same as the distribution of the key size pattern in the product area, which can better reflect the key size of the key size pattern in the product area.

[0072] Optionally, the length of the square in the first direction X is 10um, and the length in the second direction Y is 10um. The width of the lines constituting the mark and positioning pattern 202 in the mark area 106 is greater than or equal to a preset width, which is the maximum value of the line width that requires optical proximity correction (OPC), and exemplarily, the preset width is 0.25um.

[0073] Optionally, a certain blank area is set between any two of the positioning pattern 202, the logo in the logo area 106, the first sub-pattern 302, the second sub-pattern 304, the first reference pattern 306, and the second reference pattern 308 to avoid the influence of focus, energy, etc. on adjacent patterns during exposure and development.

[0074] In one embodiment, different target layers are stacked in a third direction Z, and the orthographic projections of the functional areas in the different target layers on the horizontal plane do not overlap; wherein the third direction Z is perpendicular to the horizontal plane where the first direction X and the second direction Y intersect.

[0075] Figure 4 FIG. 1 is a top view of a critical dimension test structure in the third embodiment. Figure 4 As shown, in one embodiment, the first sparse graphic area 208 is close to the first graphic area 104, the second sparse graphic area 210 is away from the first graphic area 104, and the formation process of the first sub-graphic 302 and the second sub-graphic 304 has less influence on the reference graphic extending along the third direction M than on the reference graphic extending along the fourth direction N. Optionally,

[0076] Exemplarily, the third direction M is parallel to the second direction Y, and the extension direction of the first reference pattern 306 in the first sparse pattern area 208 is the same as the second direction Y.

[0077] Optionally, the critical dimension test structure is located in the product area or in the scribe line.

[0078] Figure 5 FIG. 1 is a flow chart of a method for testing a critical dimension test structure in an embodiment. Figure 5 As shown, the present disclosure also provides a method for measuring a critical dimension test structure, comprising:

[0079] S102, providing a substrate, on which the critical dimension test structure as described above is formed.

[0080] The target layer is located on a substrate, and the substrate can be undoped single crystal silicon, single crystal silicon doped with impurities, silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI), etc.

[0081] S104, positioning the critical dimension test structure according to the coordinate information of the geometric center of the positioning area.

[0082] S106, confirming the position of the sub-graphic according to the correspondence between the geometric center of the positioning area and the geometric center of the test area in the first graphic area, and measuring the critical size of the sub-graphic.

[0083] In one embodiment, positioning the critical dimension test structure according to the coordinate information of the geometric center of the positioning area includes:

[0084] Coarsely locate the critical size test structure according to the coordinate information of the geometric center of the positioning area;

[0085] The critical dimension test structure is precisely positioned according to the geometric center of the positioning pattern.

[0086] The measurement method of the above-mentioned critical dimension test structure can locate the geometric center of the test area in the first graphic area through the coordinate information of the geometric center of the positioning area, that is, locate the position of the sub-graphic, so as to test and obtain the critical dimension of the critical dimension graphic. The shape and extension direction of the sub-graphic are not affected by the critical dimension test structure. The density of the sub-graphic in the first graphic area is equal to the density of the critical dimension graphic in the product area, eliminating the influence of the external environment on the critical dimension measurement.

[0087] It should be understood that although Figure 5 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 5 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0088] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] The above-mentioned embodiments only express several implementation methods of the embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the embodiments of the present application, and these all belong to the protection scope of the embodiments of the present application.

Claims

1. A critical dimension test structure, characterized in that: The method comprises a plurality of functional areas located in a target layer, wherein the plurality of functional areas comprises: A positioning area, including a positioning pattern, wherein the geometric center of the positioning pattern coincides with the geometric center of the positioning area; A first graphic area, comprising a plurality of sub-graphics having a critical size, wherein a density of the sub-graphics in the first graphic area is equal to a density of the critical size graphics in the product area; Among them, the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the first direction is a first preset value, and the distance between the geometric center of the positioning area and the geometric center of the test area in the first graphic area in the second direction is a second preset value, and the second direction intersects with the first direction.

2. The critical dimension test structure according to claim 1, characterized in that: The plurality of functional areas also include: The identification area corresponds one-to-one to the positioning area and the first graphic area.

3. The critical dimension test structure according to claim 1, characterized in that: The first graphic area is a dense graphic area; the plurality of functional areas further include: a sparse pattern region including a reference pattern having the same critical dimensions as the sub-pattern; Among them, the distance between the geometric center of the positioning area and the geometric center of the test area in the sparse graphic area in the first direction is a third preset value, and the distance between the geometric center of the positioning area and the geometric center of the test area in the sparse graphic area in the second direction is a fourth preset value.

4. The critical dimension test structure according to claim 3, characterized in that: The dense graphic area includes: a first dense graphic area and a second dense graphic area arranged adjacent to each other in the first direction, and the sparse graphic area includes: a first sparse graphic area and a second sparse graphic area arranged adjacent to each other in the second direction; The plurality of sub-patterns include a plurality of first sub-patterns arrayed in the first dense pattern area and a plurality of second sub-patterns arrayed in the second dense pattern area; the reference pattern includes a first reference pattern located in the first sparse pattern area and a second reference pattern located in the second sparse pattern area, the first reference pattern and the first sub-pattern are of the same type and have the same extension direction, and the second reference pattern and the second sub-pattern are of the same type and have the same extension direction; Wherein, the first sub-graph and the second sub-graph are linear graphs with different extension directions respectively; Or, the first sub-pattern and the second sub-pattern are groove-shaped patterns with different extending directions respectively; Or, the first sub-pattern and the second sub-pattern are respectively hole-shaped patterns with different radial directions; Alternatively, the first sub-graph and the second sub-graph are columnar graphs with different radial directions.

5. The critical dimension test structure according to claim 4, characterized in that: The positioning area and the sparse graphic area are arranged adjacent to each other, the first graphic area is arranged on the same side of the positioning area and the sparse graphic area, and the plurality of functional areas are arranged in a square shape; the area of ​​the square is less than or equal to 100 μm 2 , and the sizes of the first dense graphic area and the second dense graphic area are both greater than or equal to 5um*5um.

6. The critical dimension test structure according to claim 4, characterized in that: The test area in the first graphic area includes a first test area and a second test area, and the test area in the sparse graphic area includes a third test area and a fourth test area; Among them, the geometric center of the first dense graphic area coincides with the geometric center of the first test area, the geometric center of the second dense graphic area coincides with the geometric center of the second test area, the geometric center of the first sparse graphic area coincides with the geometric center of the third test area, and the geometric center of the second sparse graphic area coincides with the geometric center of the fourth test area.

7. The critical dimension test structure according to claim 4, characterized in that: The first sub-pattern and the second sub-pattern are both the linear patterns or both the groove patterns; wherein, The ends of the first sub-pattern located at the geometric center of the first dense pattern area are all provided with a first marking pattern; The ends of the second sub-pattern located at the geometric center of the second dense pattern area are all provided with second marking patterns.

8. The critical dimension test structure according to claim 4, characterized in that: The first sub-graph and the second sub-graph are both the hole-shaped graphs or both the column-shaped graphs; wherein, A third marking pattern is provided at the end of the central row and / or central column of the first dense pattern area; The end of the central row and / or central column of the second dense pattern area is provided with a fourth marking pattern.

9. The critical dimension test structure according to any one of claims 1 to 8, characterized in that: Different target layers are stacked in the third direction, and the orthographic projections of the functional areas in different target layers on the horizontal plane do not overlap; The third direction is perpendicular to the horizontal plane where the first direction and the second direction intersect.

10. A method for measuring a critical dimension test structure, characterized in that: include: Providing a substrate, on which a critical dimension test structure as described in any one of claims 1 to 9 is formed; Positioning the critical dimension test structure according to coordinate information of the geometric center of the positioning area; The position of the sub-graphic is confirmed according to the correspondence between the geometric center of the positioning area and the geometric center of the test area in the first graphic area, and the critical size of the sub-graphic is measured.

11. The measuring method according to claim 10, characterized in that: Positioning the critical dimension test structure according to the coordinate information of the geometric center of the positioning area includes: Roughly positioning the critical dimension test structure according to coordinate information of the geometric center of the positioning area; The critical dimension test structure is precisely positioned according to the geometric center of the positioning pattern.

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