Self-aligned multiple patterning mark

Abstract

The present application provides a self-aligned multiple patterning mark. The mark includes a set of patterns disposed on a substrate and a cover layer. The set of patterns includes a plurality of strip patterns extending in a first direction and disposed parallel to each other, and ends of two adjacent strip patterns are connected to each other to form an independent ring. The cover layer is disposed on the substrate and covers the set of patterns. The cover layer has openings extending in a second direction which is staggered with the first direction, and the cover layer covers opposite ends of each strip pattern.

Description

Technical Field

[0001] This invention relates to a marking for semiconductor processes, and more particularly to a self-aligned multiple patterning marking. Background Technology

[0002] In semiconductor manufacturing, alignment marks are used to check the positional alignment of a wafer or chip, while overlay marks are used to check the alignment between the previous layer and the current layer. Generally, alignment marks or overlay marks are formed in the dicing area of ​​the substrate, and after the alignment marks or overlay marks are formed, optical instruments are used to measure and determine whether the alignment is within the acceptable range through image signals.

[0003] In current self-aligned multiple patterning processes, alignment marks or overlay marks with the same or similar patterns as the components in the component area are typically formed simultaneously in the cut-out region. For example, depending on the self-aligned multiple patterning process, the alignment marks or overlay marks in the cut-out region usually include multiple strip patterns and a cover layer that partially covers these strip patterns, with the cover layer having openings exposing the strip patterns. The cover layer located in the component area is a cut layer well-known in the art. However, when performing alignment measurements with optical instruments, the boundary of the cover layer often causes poor image signals, leading to alignment measurement errors. Furthermore, for alignment marks or overlay marks, the strip patterns exposed by the openings in the cover layer are prone to tipping over. Summary of the Invention

[0004] This invention relates to a self-aligned multi-patterned mark that effectively avoids the problem of pattern tilting and improves the accuracy of alignment measurement.

[0005] According to an embodiment of the present invention, a self-aligned multi-patterned mark includes a set of patterns and a cover layer disposed on a substrate. The set of patterns includes a plurality of strip patterns extending in a first direction and arranged parallel to each other, with the ends of two adjacent strip patterns connected to each other to form independent loops. The cover layer is disposed on the substrate and covers the set of patterns. The cover layer has openings extending in a second direction intersecting the first direction, and the cover layer covers the two opposite ends of each strip pattern.

[0006] According to an embodiment of the present invention, a self-aligned multi-patterned mark includes a set of patterns and a cover layer disposed on a substrate. The set of patterns includes a plurality of strip patterns extending in a first direction and arranged parallel to each other, with the ends of two adjacent strip patterns connected to each other to form independent loops. The cover layer is disposed on the substrate and covers the set of patterns. The cover layer has a first opening and a second opening, each extending in a second direction intersecting the first direction, and the first opening and the second opening respectively expose opposite first and second ends of each strip pattern.

[0007] Based on the above, in one embodiment of the present invention, the overlay layer of the self-aligned multi-patterned mark covers the end of each strip pattern, thus effectively preventing the strip pattern from tilting. Furthermore, the opening in the overlay layer exposes a portion of the strip pattern; therefore, when the self-aligned multi-patterned mark of this embodiment is used as an alignment mark or overlay mark, the resolution of the image signal obtained by the optical instrument can be effectively improved through the boundary of the opening and the area exposed by the opening, thereby increasing the accuracy of alignment measurement.

[0008] Furthermore, in another embodiment of the invention, the overlay layer of the self-aligned multi-patterned mark covers the portion beyond the end of each strip pattern, thus effectively preventing the strip pattern from tilting. Moreover, when the self-aligned multi-patterned mark of this embodiment is used as an alignment mark or overlay mark, the resolution of the image signal obtained by the optical instrument can be effectively improved through the boundary of the opening and the area exposed by the opening, thereby increasing the accuracy of alignment measurement. Attached Figure Description

[0009] Figures 1A to 1B This is a top view schematic diagram of the manufacturing process of a self-aligned multi-patterned mark according to the first embodiment of the present invention;

[0010] Figures 2A to 2B For along Figures 1A to 1B A schematic diagram of the cross section of section II in the diagram;

[0011] Figures 3A to 3B For along Figures 1A to 1B A schematic diagram of the cross section along section II-II in the diagram;

[0012] Figure 4 This is a top view schematic diagram of a self-aligned multiple patterned mark according to a second embodiment of the present invention. Detailed Implementation

[0013] The following description provides detailed examples and accompanying drawings, but these examples are not intended to limit the scope of the invention. Furthermore, the drawings are for illustrative purposes only and are not drawn to scale. For ease of understanding, the same elements will be referred to by the same symbols in the following description.

[0014] The self-aligned multiple patterning mark of the present invention is formed in the dicing region of the substrate. It can serve as an alignment mark for checking the positional alignment of a wafer or chip, or as an overlay mark for checking the alignment between a previous layer and the current layer; the present invention is not limited thereto. Furthermore, the mark of the present invention can be formed in various self-aligned multiple patterning processes, such as self-aligned double patterning (SADP), self-aligned triple patterning (SATP), and self-aligned quadruple patterning (SAQP). The following description uses the SADP process as an example, and in this case, the mark of the present invention can be referred to as an SADP mark, but the present invention is not limited thereto.

[0015] Reference Figure 1A , Figure 2A and Figure 3A A plurality of strip-shaped dummy patterns 102 are formed on a substrate 100. The substrate 100 is the target substrate, i.e., the substrate to be patterned. For example, the substrate 100 may be a silicon substrate, and the patterned substrate 100 may be used, for example, to define trench patterns formed in the substrate 100. Alternatively, the substrate 100 may be a dielectric substrate, and the patterned substrate 100 may be used, for example, to define circuit patterns formed in the substrate 100. Alternatively, the substrate 100 may be a conductive substrate, and the patterned substrate 100 may be used, for example, to define word line structures, bit line structures, etc. However, the substrate 100 in this invention is not limited to the above descriptions.

[0016] The substrate 100 can be divided into a component region 100a and a dicing region 100b. The dicing region 100b surrounds the component region 100a. A plurality of strip-shaped dummy patterns 102 are formed on the substrate 100 in the component region 100a and the dicing region 100b, respectively. In this embodiment, in the component region 100a, each dummy pattern 102 extends in the X direction, and these dummy patterns 102 are parallel to each other in the Y direction and continuously arranged at the same spacing. Furthermore, in this embodiment, to facilitate the identification of image signals of alignment marks or overlay marks, for example, four sets of dummy patterns are formed in the dicing region 100b, and the four sets of dummy patterns are arranged parallel to each other in the Y direction and spaced apart, wherein the spacing between two adjacent sets of dummy patterns is greater than the spacing between two adjacent dummy patterns 102 in each set. However, the invention is not limited to the above-described number. In each set, each dummy pattern 102 extends in the X direction, and the layout of each set is the same.

[0017] Then, spacers 104 are formed on the sidewalls of each dummy pattern 102. Viewed from above the substrate 100, the spacers 104 surround each dummy pattern 102. The spacers 104 are formed, for example, by first conformally forming a spacer material layer on the substrate 100, and then performing an anisotropic etching process to remove a portion of the spacer material layer.

[0018] Reference Figure 1B , Figure 2B and Figure 3B The dummy pattern 102 is removed. At this time, the spacers 104 remaining on the substrate 100 in the component region 100a can serve as mask patterns for a self-aligned dual patterning process. Specifically, after removing the dummy pattern 102, a plurality of parallel strip patterns 104a, composed of spacers 104, are formed on the substrate 100. The ends of two adjacent strip patterns 104a are connected to each other to form independent annular patterns. In this embodiment, four sets of patterns are formed in the dicing region 100b, each set including four elongated annular patterns. Furthermore, each set of patterns is arranged parallel to each other on the substrate 100, and each set of patterns is identical. The distance between two adjacent strip patterns 104a in each set is equal. The distance between two adjacent sets of patterns is greater than the distance between two adjacent strip patterns 104a in each set, so that adjacent sets of patterns can be clearly separated.

[0019] Next, a capping layer 106 is formed on the substrate 100. In this embodiment, the capping layer 106 is, for example, a photoresist layer, but the invention is not limited thereto. The capping layer 106 has openings 106a and 106b in the element region 100a and the dicing region 100b, respectively, to expose a portion of the elongated annular pattern formed by the spacers 104. Specifically, in the element region 100a, the capping layer 106 covers the end of each elongated annular pattern formed by the spacers 104, and the opening 106a exposes the strip pattern 104a. Furthermore, in the dicing region 100b, the capping layer 106 covers the end of each elongated annular pattern formed by the spacers 104, and the opening 106b exposes the strip pattern 104a. In this way, the SADP mark of this embodiment, including the strip pattern 104a and the capping layer 106, is formed in the dicing region 100b. In other words, the fabrication of the SADP mark in this embodiment is integrated into the self-SADP process of the component area. Subsequently, subsequent processes can be performed, such as anisotropic etching using the cover layer 106 and the exposed strip pattern 104a as an etching mask, to complete the self-aligned dual patterning process of the substrate 100.

[0020] In this embodiment, in the cutting channel area 100b, the covering layer 106 covers the end of each elongated annular pattern formed by the spacer 104, thus effectively preventing the elongated annular patterns from tipping over. Furthermore, the opening 106b of the covering layer 106 exposes the strip pattern 104a. According to one embodiment of the invention, in the X direction (i.e., the extension direction of the strip pattern 104a), the ratio (L1 / L2) of the length L1 of the strip pattern 104a to the length L2 of the end of the annular pattern covered by the covering layer 106 is greater than 18. According to one embodiment of the invention, in the Y direction (i.e., the extension direction of the opening 106b), the ratio (D2 / D1) of the distance D2 between two adjacent sets of dummy patterns to the distance D1 between the boundary of the opening 106b and the adjacent strip pattern 104a is greater than 1 and less than 5. According to one embodiment of the present invention, the ratio (D1 / L2) of the distance D1 between the boundary of the opening 106b and the adjacent strip pattern 104a to the length L2 of the end of the annular pattern covered by the covering layer 106 is greater than 2. In this way, when the mark of this embodiment is used as an alignment mark or overlay mark, the resolution of the image signal obtained by the optical instrument can be effectively improved, thereby increasing the accuracy of alignment measurement.

[0021] Figure 4This is a top view schematic diagram of a self-aligned multiple patterned mark according to a second embodiment of the present invention. The difference between this embodiment and the first embodiment lies in the arrangement of the elongated annular patterns in the cutting area and the arrangement of the openings in the cover layer. Therefore, in this embodiment, the same components and processes as in the first embodiment will not be described again.

[0022] Reference Figure 4 In this embodiment, viewed from above the substrate 100, each elongated annular pattern formed by spacers 104 extends in the Y direction. That is, the strip pattern 104a extends in the Y direction, and the ends of two adjacent strip patterns 104a are connected to each other to form an independent ring. Furthermore, multiple strip patterns 104a are arranged parallel to each other and continuously in the X direction to form a set of patterns.

[0023] The markings in this embodiment include five sets of patterns arranged parallel to each other in the Y direction, and each set has the same layout. Each set of patterns includes 10 elongated ring patterns, that is, each set of patterns includes 20 strip patterns 104a, and the ends of two adjacent strip patterns 104a are connected to each other to form an independent ring. However, the present invention is not limited to the above-mentioned number. In each set of patterns, the distance between two adjacent strip patterns 104a is equal.

[0024] Furthermore, in this embodiment, the cover layer 106 has a plurality of openings 106b in the cut channel area 100b. These openings 106b are arranged parallel to each other in the Y direction, and each opening 106b extends in the X direction. These openings 106b expose the two opposite ends of each strip pattern 104a, that is, expose the portion where two adjacent strip patterns 104a are connected to each other. In these openings 106b, one opening 106b can expose the ends of the opposite strip patterns 104a in two adjacent sets of patterns. In other words, as shown, for two adjacent sets of patterns, the end of the strip pattern 104a in one set of patterns and the adjacent end of the strip pattern 104a in another set of patterns can be exposed through the same opening 106b. In this embodiment, viewed from above the substrate 100, the ratio (D4 / D3) of the distance D4 between two adjacent sets of patterns in the Y direction (i.e., the extension direction of the strip pattern 104a) to the distance D3 between the boundary of the opening 106b and the adjacent gap wall 104 is greater than 1 and less than 5, so that the two adjacent sets of patterns can be clearly separated.

[0025] In this embodiment, the capping layer 106 covers the portion of each set of patterns other than the ends of the strip pattern 104a. In this embodiment, the ratio (L3 / L4) of the length L3 of the annular pattern to the length L4 of the strip pattern 104a covered by the capping layer 106 is greater than 1 and less than 2. This effectively prevents the long, annular patterns from tipping over. In particular, for shorter annular patterns (e.g., less than 800 nm), tipping is also effectively prevented because the capping layer 106 covers them.

[0026] In this embodiment, since the cover layer 106 has a plurality of parallel openings 106b and these openings 106b expose the two opposite ends of each strip pattern 104a respectively, and the cover layer 106 covers the portion outside the ends of the strip pattern 104a in each group of patterns, when the mark of this embodiment is used as an alignment mark or overlay mark, the resolution of the image signal obtained by the optical instrument can be effectively improved through the boundaries of these openings 106b and the area exposed by the openings 106b, thereby increasing the accuracy of alignment measurement.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-aligned multi-patterned mark, characterized in that, include: The first set of patterns is disposed on the substrate, including multiple strip patterns that extend in a first direction and are arranged parallel to each other, and the ends of two adjacent strip patterns are connected to each other to form an independent ring; The second set of patterns is the same as the first set of patterns, wherein the first set of patterns and the second set of patterns are arranged parallel to each other on the substrate in a second direction in which the plurality of strip patterns are arranged, the second direction being different from the first direction, and the distance between the first set of patterns and the second set of patterns is greater than the distance between two adjacent strip patterns in the first set of patterns; as well as A cover layer disposed on the substrate and covering the ends of the plurality of strip patterns, wherein the cover layer has an opening extending in the second direction to expose portions beyond the ends of the plurality of strip patterns, and each boundary of the opening at its end is separated from the adjacent strip pattern.

2. The self-aligned multi-patterned mark according to claim 1, characterized in that, In the first set of patterns, the distance between two adjacent strip patterns is equal.

3. The self-aligned multi-patterned mark according to claim 1, characterized in that, In the first direction, the ratio of the length of the strip pattern to the length of the end covered by the covering layer is greater than 18.

4. The self-aligned multi-patterned mark according to claim 1, characterized in that, The ratio of the distance between the first set of patterns and the second set of patterns to the distance between the boundary of the opening and the adjacent strip pattern is greater than 1 and less than 5.

5. The self-aligned multi-patterned mark according to claim 4, characterized in that, The ratio of the distance between the boundary of the opening and the adjacent strip pattern to the length of the end covered by the covering layer is greater than 2.

6. A self-aligned multi-patterned mark, characterized in that, include: The first set of patterns, disposed on the substrate, includes a plurality of strip patterns extending in a first direction and arranged parallel to each other, wherein the ends of two adjacent strip patterns are connected to each other to form an independent ring; as well as A cover layer is disposed on the substrate and covers the first set of patterns, wherein the cover layer has a first opening and a second opening, the first opening and the second opening extending in a second direction intersecting the first direction, and the first opening and the second opening exposing the opposite first end and second end of each strip pattern, respectively.

7. The self-aligned multi-patterned mark according to claim 6, characterized in that, In the first set of patterns, the distance between two adjacent strip patterns is equal.

8. The self-aligned multi-patterned mark according to claim 6, characterized in that, It also includes a second set of patterns, wherein the first set of patterns and the second set of patterns are disposed parallel to each other on the substrate in the first direction, the second set of patterns is the same as the first set of patterns, and the cover layer further has a third opening, wherein the first opening exposes the first end of each strip pattern in the first set of patterns, the second opening exposes the second end of each strip pattern in the first set of patterns and one end of each strip pattern in the second set of patterns, and the third opening exposes the other end of each strip pattern in the second set of patterns.

9. The self-aligned multi-patterned mark according to claim 8, characterized in that, In the first direction, the ratio of the distance between the first set of patterns and the second set of patterns to the distance between the boundary of the opening and the adjacent independent ring is greater than 1 and less than 5.

10. The self-aligned multi-patterned mark according to claim 9, characterized in that, The ratio of the length of the independent ring to the length of the strip pattern covered by the covering layer is greater than 1 and less than 2.

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