Optical proximity correction method, mask and semiconductor structure forming method

Abstract

The invention discloses an optical proximity correction method, a mask plate and a semiconductor structure forming method, and the optical proximity correction method comprises the steps: obtaining a reference layout which comprises a plurality of first metal wire patterns, a plurality of second metal wire patterns and a plurality of cutting patterns; a to-be-corrected graph is obtained from the multiple cut-off graphs, the to-be-corrected graph comprises a first to-be-corrected graph and a second to-be-corrected graph, the first to-be-corrected graph and the second to-be-corrected graph are adjacent, and the distance between the first to-be-corrected graph and the second to-be-corrected graph is smaller than a first preset size; determining a target reference pattern corresponding to the to-be-corrected pattern from the plurality of second metal wire patterns; on the basis of the target reference graph, the first to-be-corrected graph and the second to-be-corrected graph are combined and corrected, a combined graph is obtained, the combined graph is formed, and the situation that a mask design rule is violated is avoided.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to an optical proximity correction method, a photomask, and a method for forming semiconductor structures. Background Technology

[0002] In semiconductor manufacturing, as design dimensions continue to shrink, the optical proximity effect (OPE) caused by the exposure system becomes increasingly pronounced. To address this, optical proximity correction (OPC) is employed to correct errors in the photolithography process. This involves pre-processing the photomask before photolithography to achieve pre-correction, ensuring that the amount of correction and compensation precisely compensates for the OPE caused by the exposure system. The photomask fabricated from the OPC-corrected wafer pattern, after photolithography, can produce the desired target pattern on the wafer.

[0003] As the critical dimensions of semiconductor devices continue to shrink, pattern density is becoming far beyond the limits of single-exposure processing. Therefore, based on the conventional coating-exposure-development-etching process, multi-layer lithography has been developed. The core of multi-layer lithography is to split the pattern originally created in a single layer onto two or more masks, using multiple lithography and etching processes to achieve the original single-layer design. Multi-layer lithography is advantageous for achieving higher pattern density and smaller process nodes. In one type of multi-layer lithography process, one-dimensional lines are first formed using techniques such as lithography and etching (LE), double lithography (LELE), or self-aligned double imaging (SADP). Then, another lithography and etching process is used to cut these one-dimensional lines to achieve the desired pattern.

[0004] However, as critical dimensions continue to shrink, the distance between the patterns used for cutting also decreases further, exceeding the resolution limit of the current layer's light source, which violates the Mask Rule Check (MRC). This situation leads to a sharp drop in the process window, making the process uncontrollable.

[0005] Therefore, there is an urgent need for a method to perform optical proximity correction on the cut pattern in order to obtain the desired target pattern on the wafer. Summary of the Invention

[0006] The technical problem solved by this invention is to provide an optical proximity correction method, a photomask, and a method for forming semiconductor structures to improve the accuracy of forming target patterns on wafers.

[0007] To address the aforementioned problems, the present invention provides an optical proximity correction method, comprising: acquiring a reference pattern, the reference pattern including: a plurality of first metal line patterns, a plurality of second metal line patterns, and a plurality of cut patterns, wherein the plurality of first metal line patterns and the plurality of second metal line patterns extend along a first direction and are arranged along a second direction, each of the first metal line patterns being located between two adjacent second metal line patterns, and the plurality of cut patterns extending along the second direction, and having an overlapping area between the plurality of cut patterns and the plurality of first metal line patterns; acquiring a pattern to be corrected from the plurality of cut patterns, the pattern to be corrected including a first pattern to be corrected and a second pattern to be corrected, the first pattern to be corrected and the second pattern to be corrected being adjacent, and the distance between the first pattern to be corrected and the second pattern to be corrected being less than a first preset size; determining a target reference pattern corresponding to the pattern to be corrected from the plurality of second metal line patterns; and performing a first merging correction on the first pattern to be corrected and the second pattern to be corrected based on the target reference pattern to obtain a merged pattern.

[0008] Optionally, determining the target reference pattern corresponding to the pattern to be corrected from the plurality of second metal line patterns includes: using the first metal line pattern that overlaps with the first pattern to be corrected as a first reference pattern; using the first metal line pattern that overlaps with the second pattern to be corrected as a second reference pattern; and determining the second metal line pattern between the first reference pattern and the second reference pattern as the target reference pattern.

[0009] Optionally, the step of merging and correcting the first and second images to be corrected based on the target reference image to obtain a merged image includes: obtaining the centerline of the target reference image, the centerline being parallel to the first direction; extending the first and second images to be corrected along the second direction to their ends exceeding the target length of the centerline, respectively, to obtain a first corrected image and a second corrected image, the target being half of a second preset size; establishing a connecting image with the centerline as the center line, the width of the connecting image being the second preset size, one end of the connecting image being flush with the end of the first corrected image and the other end being flush with the end of the second corrected image in the second direction, and one end of the connecting image overlapping the side of the first corrected image and the other end overlapping the side of the second corrected image in the first direction; merging the first corrected image, the second corrected image, and the connecting image to form the merged image.

[0010] Optionally, the step of extending the first and second shapes to be corrected along the second direction to the ends exceeding the target length of the centerline to obtain the first and second corrected shapes includes: extending the first and second shapes to be corrected along the second direction to the ends being flush with the centerline; extending the first shape to be corrected further along the second direction to the target length to obtain the first corrected shape; and extending the second shape to be corrected further along the second direction to the target length to obtain the second corrected shape.

[0011] Optionally, the method for forming the merged pattern further includes: before merging the first modified pattern, the second modified pattern, and the connecting pattern, further including: enlarging the first modified pattern and the second modified pattern along the first direction to a third preset size; the third preset size is the limit size of the photolithography process.

[0012] Optionally, the first preset size is the limit size of the photolithography process; the second preset size is greater than or equal to the limit size of the photolithography process.

[0013] Optionally, the plurality of first metal line patterns include a plurality of first type metal line patterns; the plurality of second metal line patterns include a plurality of power rail patterns and a plurality of second type metal line patterns, wherein the width of the power rail pattern is greater than the width of the first type metal line pattern.

[0014] Optionally, both the first reference pattern and the second reference pattern are the first type of metal line pattern, and the target reference pattern is the power rail pattern.

[0015] Optionally, the optical proximity correction method further includes: forming a cut-off layout using the cut-off pattern other than the pattern to be corrected in the merged pattern and the reference layout.

[0016] Optionally, it also includes: forming a first metal layer layout with a plurality of first metal line patterns; and forming a second metal layer layout with a plurality of second metal line patterns.

[0017] Optionally, the method for obtaining the reference layout includes: providing an initial layout, the initial layout including a plurality of initial graphics; splitting the initial layout to obtain the reference layout, wherein the plurality of initial graphics are split into a plurality of first metal line graphics, a plurality of second metal line graphics and a plurality of cut-off graphics.

[0018] Accordingly, the technical solution of the present invention also provides a photomask having a pattern formed using the optical proximity correction method described above.

[0019] Accordingly, the present invention also provides a method for forming a semiconductor structure, comprising: obtaining a cutting mask having a pattern formed by the optical proximity correction method described above; providing a substrate; forming a metal layer on the surface of the substrate, the metal layer comprising a plurality of metal line structures, the plurality of metal line structures being parallel to a third direction and arranged along a fourth direction, the third direction and the fourth direction being perpendicular to each other and parallel to the surface of the substrate; forming a pattern transfer layer and a photoresist layer on the metal layer; using the cutting mask as a mask, patterning the photoresist layer to transfer the pattern on the cutting mask to the photoresist layer; using the patterned photoresist layer as a mask, etching the pattern transfer layer and the metal layer to form an opening in the metal line structure, the opening penetrating the metal line structure along the fourth direction; forming a sidewall material layer in the opening, the sidewall material layer in the opening serving as an isolation structure.

[0020] Accordingly, the present invention also provides another method for forming a semiconductor structure, comprising: obtaining a cutting mask having a pattern formed by the optical proximity correction method described above; providing a substrate having a second metal layer on its surface, the second metal layer including a plurality of second metal line structures and a plurality of grooves, the grooves being located between adjacent second metal line structures, the plurality of second metal line structures being parallel to a third direction and arranged along a fourth direction, the third direction and the fourth direction being perpendicular to each other; forming a pattern transfer layer and a photoresist layer on the pattern transfer layer on the substrate surface and in the grooves; patterning the photoresist layer using the cutting mask as a mask to transfer the pattern on the cutting mask to the photoresist layer; etching the pattern transfer layer using the patterned photoresist layer as a mask to form an opening in the pattern transfer layer in the grooves; and forming an isolation structure in the opening.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] In the optical proximity correction method of the present invention, among several cut patterns, a first pattern to be corrected and a second pattern to be corrected that violate the mask design rules are obtained. By merging and correcting the first pattern to be corrected and the second pattern to be corrected, a merged pattern is obtained, which avoids the situation of violating the mask design rules. The corrected merged pattern can be converted into a pattern that the light source can resolve, so that it is completely controllable in the entire process, thereby expanding the process window and improving the degree of design freedom.

[0023] Furthermore, the first and second images to be corrected are merged and corrected to obtain a merged image, which includes: obtaining the centerline of the target reference image, the centerline being parallel to the first direction; and extending the first and second images to be corrected along the second direction to the ends exceeding the target length of the centerline, respectively, to obtain the first and second corrected images, the target length being half of a second preset size. In the above method, the extension length of the first and second images to be corrected does not need to be preset to a fixed value. The extension length depends on the position of the centerline and the second preset size. The position of the centerline depends on the structure of the layout, and the second preset size can be adjusted according to the process node. Therefore, it can adapt to different process nodes and different layout structures, making the optical proximity correction method simpler and more universal. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a metal layer layout;

[0025] Figure 2 and Figure 3 This is a flowchart of the optical proximity correction method according to an embodiment of the present invention;

[0026] Figures 4 to 14 This is a schematic diagram of the layout structure of each step of the optical proximity correction method in an embodiment of the present invention;

[0027] Figures 15 to 17 This is a schematic diagram of the steps in the method for forming a semiconductor structure according to an embodiment of the present invention;

[0028] Figures 18 to 19 This is a schematic diagram of the steps in the method for forming a semiconductor structure according to another embodiment of the present invention. Detailed Implementation

[0029] As described in the background section, there is a need for a method for optical proximity correction of cut patterns to obtain the desired target pattern on a wafer. This will be explained in detail below with reference to the accompanying drawings.

[0030] Figure 1 This is a schematic diagram of the structure of a metal layer layout.

[0031] Please refer to Figure 1The metal layer layout includes: a plurality of first metal line patterns 101, a plurality of power line patterns 102, a plurality of second metal line patterns 103, and a plurality of cut patterns 104. The plurality of first metal line patterns 101, the plurality of power line patterns 102, and the plurality of second metal line patterns 103 are all parallel to a first direction X, and the plurality of cut patterns 104 are parallel to a second direction Y. The first direction X and the second direction Y are perpendicular to each other, and there is a first overlap area between the plurality of cut patterns 104 and the plurality of first metal line patterns 101.

[0032] For the purpose of explanation, Figure 1 A via layer is also superimposed on the metal layer layout. The via layer includes a plurality of metal via patterns 105, and there is a second overlap region between the plurality of metal via patterns 105 and the plurality of first metal line patterns 101. The metal layer layout is used to provide the pattern for forming the metal layer. Specifically, a plurality of first metal line patterns 101 and a plurality of power line patterns 102 constitute the first metal layer layout, a plurality of second metal line patterns 103 constitute the second metal layer layout, and a plurality of cut patterns 104 constitute the cut layout.

[0033] In the fabrication of the back-end metal conductive layers, as the critical pitch gradually approaches the resolution limit of the DUV lithography machine, and the pitch of the metal vias continues to shrink, higher process requirements are placed on the formation of head-to-head patterns for small-cycle and small-size metal layers. Therefore, to obtain the required patterns, multiple lithography processes are required. Here, lithography and etching are performed based on the first metal pattern to form one-dimensional lines. Based on the cut pattern 104 in the cut pattern, the lines are then cut again using lithography and etching to obtain the required head-to-head patterns.

[0034] However, due to limitations in the design of the through-hole layer (see reference) Figure 1 The distribution of the through-hole pattern 105 in the metal conductor layer results in a high head-to-head density, causing the cut-off patterns 104 to be too close together (as shown by the dashed line), exceeding the resolution limit of the current layer's light source and violating the MRC (Mean Correction Control). This situation leads to a sharp decrease in the process window, making the process uncontrollable.

[0035] To address the aforementioned problems, this invention provides an optical proximity correction method, a photomask, and a semiconductor structure formation method. In this method, among several cut patterns, a first pattern to be corrected and a second pattern to be corrected that violate photomask design rules are obtained. By performing a first merging correction on the first and second patterns to be corrected, a merged pattern is obtained. This avoids violations of photomask design rules and allows the corrected merged pattern to be converted into a pattern that the light source can resolve, thus making it completely controllable throughout the entire process. This achieves the goal of expanding the process window and increasing design freedom.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Figure 2 and Figure 3 This is a flowchart of the optical proximity correction method according to an embodiment of the present invention.

[0038] Please refer to Figure 2 The optical proximity correction method includes the following steps:

[0039] Step S201: Obtain a reference layout, which includes a plurality of first metal line patterns, a plurality of second metal line patterns, and a plurality of cut patterns. The plurality of first metal line patterns and the plurality of second metal line patterns extend along a first direction and are arranged along a second direction. Each first metal line pattern is located between two adjacent second metal line patterns. The plurality of cut patterns extend along the second direction and have overlapping areas with the plurality of first metal line patterns.

[0040] Step S202: Obtain the pattern to be corrected from the plurality of cut patterns. The pattern to be corrected includes a first pattern to be corrected and a second pattern to be corrected. The first pattern to be corrected and the second pattern to be corrected are adjacent to each other, and the distance between the first pattern to be corrected and the second pattern to be corrected is less than a first preset size.

[0041] Step S203: Determine the target reference pattern corresponding to the pattern to be corrected from the plurality of second metal line patterns.

[0042] Step S204: Based on the target reference graphic, perform a first merging correction on the first graphic to be corrected and the second graphic to be corrected to obtain a merged graphic.

[0043] In this embodiment, the optical proximity correction method further includes:

[0044] Step S205: The cut layout is formed by combining the merged graphic and the cut graphic other than the graphic to be corrected in the reference layout.

[0045] The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.

[0046] Figures 4 to 12 This is a schematic diagram of the layout structure of each step of the optical proximity correction method in an embodiment of the present invention.

[0047] Please refer to Figure 4 and Figure 5 , Figure 4 The image shows the areas where several cut patterns 501 are located. Figure 5 The area containing several second cut patterns 601 is shown. The reference layout includes several first metal wire patterns 301, several second metal wire patterns 401, and several cut patterns 501. The several first metal wire patterns 301 and several second metal wire patterns 401 extend along a first direction X and are arranged along a second direction Y. Each first metal wire pattern 301 is located between two adjacent second metal wire patterns 401. The several cut patterns 501 extend along the second direction Y and have overlapping areas with the several first metal wire patterns 301.

[0048] In this embodiment, the plurality of first metal line patterns 301 include a plurality of first type metal line patterns 3011; the plurality of second metal line patterns 401 include a plurality of power track patterns 4010 and a plurality of second type metal line patterns 4011, wherein the width of the power track pattern 4010 is greater than the width of the first type metal line pattern 3011.

[0049] In semiconductor manufacturing, a first metal line is obtained by splitting the pattern onto a first metal layer mask and a first cutting mask, forming the first metal line through a single photolithography and etching process, and then cutting the first metal line through another photolithography and etching process. The first metal layer mask has a pattern obtained after modifying several first metal line patterns 301, and the first cutting mask has a pattern obtained after modifying several cutting patterns 501.

[0050] Specifically, the first metal wire pattern 301 is used to form a first metal wire structure, the first metal wire structure includes a first type of metal wire structure, and the cutting pattern 501 is used to form a pattern for cutting the first metal wire structure.

[0051] More specifically, the first type of metal wire pattern 3011 is used to form a first type of metal wire structure, and the cutting pattern 501 is a pattern used to cut the first type of metal wire structure.

[0052] More specifically, the overlapping areas between the plurality of cut patterns 501 and the plurality of first-type metal wire patterns 3011 correspond to the areas where the first-type metal wire structure is cut.

[0053] It should be noted that the width mentioned in this article refers to the dimension along the second direction Y.

[0054] In this embodiment, the plurality of first metal line patterns 301 further include a plurality of second power track patterns 3010, wherein the width of the second power track pattern 3010 is greater than the width of the first type of metal line 3011.

[0055] In this embodiment, the reference layout further includes a plurality of second cut patterns 601, which extend along the second direction Y, and have overlapping areas with the plurality of second type metal wire patterns 4011.

[0056] In semiconductor manufacturing, a second metal line is obtained by splitting the pattern onto a second metal layer mask and a second cutting mask, forming the second metal line through a single photolithography and etching process, and then cutting the second metal line through another photolithography and etching process. The second metal layer mask has a plurality of patterns obtained after modifying the second metal line pattern 401, and the second cutting mask has a plurality of patterns obtained after modifying the second cutting pattern 601.

[0057] Specifically, the second metal wire pattern 401 is used to form a second metal wire structure, the second metal wire structure includes a second type of metal wire structure, and the second cutting pattern 601 is used to form a pattern for cutting the second metal wire structure.

[0058] More specifically, the second type of metal wire pattern 4011 is used to form a second type of metal wire structure, and the second cutting pattern 601 is used to form a pattern for cutting the second type of metal wire structure.

[0059] More specifically, the overlapping areas between the second cut patterns 601 and the second type of metal wire patterns 4011 correspond to the areas where the second type of metal wire structure is cut.

[0060] In this embodiment, the method for obtaining the reference layout includes: providing an initial layout, the initial layout including a plurality of initial graphics; splitting the initial layout to obtain the reference layout, wherein the plurality of initial graphics are split into a plurality of first metal line graphics 301, a plurality of second metal line graphics 401, and a plurality of cut graphics 501.

[0061] In this embodiment, the initial patterns are further divided into a number of second cut-off patterns 601.

[0062] Please Figure 4 Based on, refer to Figure 6In a plurality of cut-off patterns 501, a pattern to be corrected is obtained. The pattern to be corrected includes a first pattern to be corrected 5011 and a second pattern to be corrected 5012. The first pattern to be corrected 5011 and the second pattern to be corrected 5012 are adjacent to each other, and the distance d1 between the first pattern to be corrected 5011 and the second pattern to be corrected 5012 is less than a first preset size.

[0063] In this embodiment, the first preset size is the limit size of the photolithography process. The subsequent objective is to: modify the first pattern to be modified 5011 and the second pattern to be modified 5012 to convert them into patterns that can be resolved by the light source, and after transferring the modified patterns to the wafer surface, make the pattern on the wafer surface conform to expectations, thereby making the final semiconductor structure conform to expectations.

[0064] Please continue to refer to this. Figure 4 and Figure 6 A target reference pattern 301c corresponding to the pattern to be corrected is determined from the plurality of second metal line patterns 401.

[0065] In this embodiment, determining the target reference pattern corresponding to the pattern to be corrected from the plurality of second metal line patterns 401 includes: taking the first metal line pattern 301 that has an overlapping area with the first pattern to be corrected 5011 as the first reference pattern 301a; taking the first metal line pattern 301 that has an overlapping area with the second pattern to be corrected 5012 as the second reference pattern 301b; and determining the second metal line pattern 401 between the first reference pattern 301a and the second reference pattern 301b as the target reference pattern 301c.

[0066] In this embodiment, the first reference pattern 301a and the second reference pattern 301b are both the first type of metal line pattern 3011, and the target reference pattern 301c is the power rail pattern 4010.

[0067] Please refer to Figures 7 to 12 Based on the target reference graphic 301c, the first graphic to be corrected 5011 and the second graphic to be corrected 5012 are merged and corrected to obtain a merged graphic.

[0068] In this embodiment, based on the target reference graphic 301c, the first graphic to be corrected 5011 and the second graphic to be corrected 5012 are merged and corrected to obtain a merged graphic. Please refer to [the relevant documentation]. Figure 3 This includes the following steps:

[0069] Step S2041: Obtain the centerline of the target reference graphic, wherein the centerline is parallel to the first direction;

[0070] Step S2042: The first shape to be corrected and the second shape to be corrected are extended along the second direction until their ends exceed the target length of the centerline, respectively, to obtain the first corrected shape and the second corrected shape, wherein the target length is half of the second preset size;

[0071] Step S2043: Using the center line as the center line, establish a connecting pattern. The width of the connecting pattern is the second preset size. One end of the connecting pattern is flush with the end of the first correction pattern in the second direction, and the other end is flush with the end of the second correction pattern. In the first direction, one end of the connecting pattern overlaps with the side of the first correction pattern, and the other end overlaps with the side of the second correction pattern.

[0072] Step S2044: Merge the first corrected graphic, the second corrected graphic, and the connecting graphic to form the merged graphic.

[0073] The following is in conjunction with the appendix Figures 7 to 12 Please provide a detailed explanation.

[0074] Please refer to Figure 7 The centerline NN' of the target reference pattern 301c is obtained, and the centerline NN' is parallel to the first direction X.

[0075] In this embodiment, the method for obtaining the centerline NN' includes: using the center-line algorithm built into the EDA tool to generate the centerline of the target reference graphic 301c.

[0076] Subsequently, the first and second shapes to be corrected are extended along the second direction until their ends exceed the target length of the centerline, respectively, to obtain the first and second corrected shapes.

[0077] Here, the extension lengths of the first and second patterns to be corrected do not need to be preset to a fixed value. The extension lengths depend on the position of the center line and the second preset size. The position of the center line depends on the structure of the layout, and the second preset size can be adjusted according to the process node. Therefore, it can adapt to different process nodes and different layout structures, making the optical proximity correction method simpler and more universal.

[0078] In this embodiment, the first and second shapes to be corrected are extended along the second direction until their ends exceed the target length of the centerline, respectively, to obtain the first and second corrected shapes. Please refer to [the relevant documentation] for details. Figures 8 to 9 .

[0079] Please refer to Figure 8The first shape to be corrected 5011 and the second shape to be corrected 5012 are respectively extended along the second direction Y to their ends and flush with the centerline NN'.

[0080] In this embodiment, the algorithm for extending the first graphic to be corrected 5011 and the second graphic to be corrected 5012 along the second direction Y to the end that is flush with the centerline NN' includes the grow-until algorithm.

[0081] Here, the centerline NN' is generated using the center-line algorithm built into the EDA tool, and the grow-until algorithm is used to extend the first and second graphics to be corrected to the centerline NN'. The extension length does not need to be preset to a fixed value. Therefore, it can adapt to the structure of different nodes and different layouts, making the optical proximity correction method simpler and more universal.

[0082] Please refer to Figure 9 The first pattern to be corrected 5011 is extended along the second direction Y to the target length to obtain the first corrected pattern 5013; the second pattern to be corrected 5012 is extended along the second direction Y to the target length to obtain the second corrected pattern 5014.

[0083] The target length is half of the second preset size d2.

[0084] In this embodiment, the second preset size d2 is greater than or equal to the photolithography process limit size.

[0085] Please refer to Figure 10 With the center line NN' as the center line, a connecting pattern 5015 is established. The width of the connecting pattern 5015 is the second preset size. One end of the connecting pattern 5015 is flush with the end of the first modified pattern 5013 in the second direction Y, and the other end is flush with the end of the second modified pattern 5014. In the first direction X, one end of the connecting pattern 5015 overlaps with the side of the first modified pattern 5013, and the other end overlaps with the side of the second modified pattern 5014.

[0086] Subsequently, the first corrected graphic 5013, the second corrected graphic 5014, and the connecting graphic 5015 are merged to form the merged graphic.

[0087] In this embodiment, before merging the first corrected graphic 5013, the second corrected graphic 5014, and the connecting graphic 5015, please refer to... Figure 11 .

[0088] Please refer to Figure 11This enlarges the first corrected graphic 5013 and the second corrected graphic 5014 to a third preset size along the first direction X.

[0089] Specifically, the two adjacent ends of the first corrected pattern 5013 and the second corrected pattern 5014 are kept stationary, and the first corrected pattern 5013 and the second corrected pattern 5014 are enlarged along the second direction Y.

[0090] In this embodiment, the third preset size is the limit size of the photolithography process. The purpose of enlarging the first modified pattern 5013 and the second modified pattern 5014 along the first direction X is to make the pattern size large enough to be exposed.

[0091] Please refer to Figure 12 The first corrected graphic 5013, the second corrected graphic 5014, and the connecting graphic 5015 are merged to form a merged graphic 5016.

[0092] Thus, among the several cut patterns, a first pattern 5011 and a second pattern 5012 that violate the mask design rules are obtained. By performing a first merging correction on the first pattern 5011 and the second pattern 5012, a merged pattern is obtained, which avoids the situation of violating the mask design rules. The corrected merged pattern can be converted into a pattern that the light source can resolve, thereby making it completely controllable throughout the process, so as to expand the process window and improve the degree of design freedom.

[0093] In this embodiment, after the first corrected pattern 5013 and the second corrected pattern 5014 are enlarged along the second direction Y, the first corrected pattern 5013, the second corrected pattern 5014 and the connecting pattern 5015 are merged to form a merged pattern 5016.

[0094] It should be noted that, since the overlapping area between the merged pattern and the first metal line pattern corresponds to the cutting area of ​​the first metal line, and the connecting pattern 5015 is located between adjacent first metal line patterns, adding the connecting pattern 5015 will not add extra cutting to the first metal line.

[0095] In this embodiment, please refer to the optical proximity correction method. Figure 2 This includes: forming a cut layout using the merged graphic 5016 and the cut graphic 501 other than the graphic to be corrected in the reference layout.

[0096] In this embodiment, a third and a fourth pattern to be corrected are also obtained from a plurality of the second cut-out patterns 601, and the third and fourth patterns to be corrected are merged and corrected to obtain a second merged pattern. Specifically, please refer to... Figure 5 Based on this, continue to refer to Figure 13 and Figure 14 .

[0097] Please refer to Figure 13 In a plurality of second cutting patterns 601, a third pattern to be corrected 6011 and a fourth pattern to be corrected 6012 are obtained, wherein the third pattern to be corrected 6011 and the fourth pattern to be corrected 6012 are adjacent, and the distance between the third pattern to be corrected 6011 and the fourth pattern to be corrected 6012 is less than the first preset size; and a second target reference pattern 401c is determined from a plurality of first metal wire patterns 301.

[0098] Specifically, the second type of metal line pattern 4011, which has an overlapping area with the third pattern to be corrected 6011, is designated as the fourth reference pattern 401a; the second type of metal line pattern 4011, which has an overlapping area with the second pattern to be corrected 6012, is designated as the fifth reference pattern 401b; and the second power track pattern 3010 between the fourth reference pattern and the fifth reference pattern is designated as the second target reference pattern 401c.

[0099] Please refer to Figure 14 Based on the second target reference graphic, the third graphic to be corrected 401a and the fourth graphic to be corrected 401b are merged and corrected to obtain the second merged graphic 6013.

[0100] In this embodiment, the step of merging and correcting the third image to be corrected 401a and the fourth image to be corrected 401b based on the second target reference image to obtain the second merged image 6013 includes: obtaining the second centerline MM' of the second target reference image 401c, wherein the second centerline MM' is parallel to the first direction X; extending the third image to be corrected 6011 along the second direction Y to its end flush with the second centerline MM'; extending the fourth image to be corrected 6012 along the second direction Y to its end flush with the second centerline MM'; and continuing to extend the third image to be corrected 6011 along the second direction Y for a length equal to half of the second preset size to obtain the third image 6013. A positive shape (not shown in the figure); the fourth shape to be corrected 6012 is extended along the second direction Y, with an extension length of half the second preset size, to obtain a fourth corrected shape (not shown in the figure); a second connecting shape (not shown in the figure) is established with the second centerline MM' as the center line, one end of the second connecting shape is flush with the end of the third corrected shape in the second direction Y, and the other end is flush with the end of the fourth corrected shape; one end of the second connecting shape overlaps with the side of the third corrected shape in the first direction X, and the other end overlaps with the side of the fourth corrected shape; the third corrected shape, the fourth corrected shape and the second connecting shape are merged to form a second merged shape 6013.

[0101] It should be noted that the method for forming the second merged graphic is the same as the method for forming merged graphics described above, and will not be repeated here.

[0102] In this embodiment, the optical proximity correction method further includes: forming a second cut pattern with the second merged pattern 6013 and the second cut pattern 601 other than the pattern to be corrected in the reference pattern.

[0103] In this embodiment, a first metal layer layout is formed by a plurality of first metal line patterns 301; and a second metal layer layout is formed by a plurality of second metal line patterns 401.

[0104] Accordingly, embodiments of the present invention also provide a photomask having a pattern formed using the optical proximity correction method described above.

[0105] Accordingly, embodiments of the present invention also provide a method for forming a semiconductor structure, please refer to... Figures 15 to 17 .

[0106] Figures 15 to 17 This is a schematic diagram of the steps in the method for forming a semiconductor structure according to an embodiment of the present invention.

[0107] In this embodiment, the method for forming the semiconductor structure includes: obtaining a cutting mask having a pattern formed by the optical proximity correction method as described above.

[0108] Specifically, the cutting mask is generated based on the cutting pattern in the optical proximity correction method described above.

[0109] Please refer to Figure 15 A substrate 701 is provided; a first metal layer is formed on the surface of the substrate 701, the first metal layer including a plurality of first metal line structures 702, the plurality of first metal line structures 702 being parallel to a third direction x and arranged along a fourth direction y, the third direction x and the fourth direction y being perpendicular to each other and parallel to the surface of the substrate 701.

[0110] In this embodiment, the material of several metal wire structures 702 is amorphous silicon.

[0111] In this embodiment, a first metal mask is formed based on the first metal layer pattern in the optical proximity correction method described above. The first metal mask is used to form the first metal layer, and the first metal line pattern is used to form the pattern of the first metal line structure 702.

[0112] Please refer to Figure 16 A pattern transfer layer (not shown in the figure) and a photoresist layer (not shown in the figure) are formed on the first metal layer; the photoresist layer is patterned using the cutting mask as a mask so that the pattern on the cutting mask is transferred to the photoresist layer; the patterned photoresist layer is used as a mask to etch the pattern transfer layer and the first metal layer to form an opening 703 in the first metal line structure 702, the opening 703 penetrating the first metal line structure 702 along the fourth direction y.

[0113] In this embodiment, the material of the pattern transfer layer is spin-on carbon (SOC).

[0114] Please refer to Figure 17 A sidewall material layer 704 is formed within the opening 703, and the sidewall material layer 704 within the opening 703 serves as an isolation structure 705.

[0115] Accordingly, embodiments of the present invention also provide another method for forming a semiconductor structure, please refer to... Figure 18 and Figure 19 .

[0116] The main difference between this embodiment and the previous embodiment is that the method of forming the isolation structure is different.

[0117] Figures 18 to 19 This is a schematic diagram of the steps in the method for forming a semiconductor structure according to another embodiment of the present invention.

[0118] In this embodiment, the method for forming the semiconductor structure includes: obtaining a cutting mask having a pattern formed by the optical proximity correction method as described above.

[0119] Specifically, the cutting mask is generated based on the cutting pattern in the optical proximity correction method described above.

[0120] Please refer to Figure 18 A substrate 801 is provided, the surface of which has a second metal layer. The second metal layer includes a plurality of second metal line structures 802 and a plurality of grooves 805. The grooves 805 are located between adjacent second metal line structures 802. The plurality of second metal line structures 802 are parallel to a third direction x and arranged along a fourth direction y. The third direction x and the fourth direction y are perpendicular to each other.

[0121] In this embodiment, the second metal wire structure 802 has a second opening (not shown in the figure), and the second opening penetrates the second metal wire structure 802 along the fourth direction y; the surface of the substrate 801, the inside of the second opening and the surface of the second metal wire structure 802 have sidewall material 804, and the sidewall material 804 inside the second opening is used to cut the second metal wire structure 802.

[0122] Here, based on the second metal layer layout in the optical proximity correction method described above, the pattern of the second metal line structure 802 is formed, and based on the second cut-off layout in the optical proximity correction method described above, the pattern of the first opening is formed.

[0123] Please refer to Figure 19 A pattern transfer layer (not shown) and a photoresist layer (not shown) on the pattern transfer layer are formed on the surface of the substrate 801 and in the groove 805. The photoresist layer is patterned using the cutting mask as a mask so that the pattern on the cutting mask is transferred to the photoresist layer. The pattern transfer layer is etched using the patterned photoresist layer as a mask to form an opening (not shown) in the pattern transfer layer in the groove 805. An isolation structure 806 is formed in the opening.

[0124] After the isolation structure 806 is formed, the graphics transfer layer is also removed.

[0125] Subsequently, a first metal mask is formed based on the first metal layer pattern in the optical proximity correction method described above; using the first metal mask as a mask, the pattern is transferred onto the substrate 801 to form a first metal line structure (not shown in the figure) between adjacent second metal line structures 802, and the isolation structure 806 penetrates the first metal line structure along the fourth direction y to cut the first metal line structure.

[0126] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An optical proximity correction method, characterized in that, include: Obtain a reference layout, the reference layout including: a plurality of first metal line patterns, a plurality of second metal line patterns and a plurality of cut patterns, the plurality of first metal line patterns and the plurality of second metal line patterns all extend along a first direction and are arranged along a second direction, each of the first metal line patterns is located between two adjacent second metal line patterns, the plurality of cut patterns extend along the second direction, and there is an overlapping area between the plurality of cut patterns and the plurality of first metal line patterns; A pattern to be corrected is obtained from several cut patterns. The pattern to be corrected includes a first pattern to be corrected and a second pattern to be corrected. The first pattern to be corrected and the second pattern to be corrected are adjacent to each other, and the distance between the first pattern to be corrected and the second pattern to be corrected is less than a first preset size. A target reference pattern corresponding to the pattern to be corrected is determined from the plurality of second metal line patterns; based on the target reference pattern, the first pattern to be corrected and the second pattern to be corrected are merged and corrected to obtain a merged pattern.

2. The optical proximity correction method as described in claim 1, characterized in that, The step of determining the target reference pattern corresponding to the pattern to be corrected from the plurality of second metal line patterns includes: taking the first metal line pattern that has an overlapping area with the first pattern to be corrected as the first reference pattern; taking the first metal line pattern that has an overlapping area with the second pattern to be corrected as the second reference pattern; and determining the second metal line pattern between the first reference pattern and the second reference pattern as the target reference pattern.

3. The optical proximity correction method as described in claim 1, characterized in that, The step of merging and correcting the first and second images to be corrected based on the target reference image to obtain a merged image includes: obtaining the centerline of the target reference image, the centerline being parallel to the first direction; extending the first and second images to be corrected along the second direction to their ends exceeding the target length of the centerline, respectively, to obtain a first corrected image and a second corrected image, the target length being half of a second preset size; establishing a connecting image with the centerline as the center line, the width of the connecting image being the second preset size, one end of the connecting image being flush with the end of the first corrected image and the other end being flush with the end of the second corrected image in the second direction, and one end of the connecting image overlapping the side of the first corrected image and the other end overlapping the side of the second corrected image in the first direction; and merging the first corrected image, the second corrected image, and the connecting image to form the merged image.

4. The optical proximity correction method as described in claim 3, characterized in that, The step of extending the first and second shapes to be corrected along the second direction to their ends beyond the target length of the centerline to obtain the first and second corrected shapes includes: extending the first and second shapes to be corrected along the second direction to their ends flush with the centerline; extending the first shape to be corrected further along the second direction to the target length to obtain the first corrected shape; and extending the second shape to be corrected further along the second direction to the target length to obtain the second corrected shape.

5. The optical proximity correction method as described in claim 3, characterized in that, The method for forming the merged pattern further includes: before merging the first modified pattern, the second modified pattern, and the connecting pattern, enlarging the first modified pattern and the second modified pattern along the first direction to a third preset size; the third preset size is the limit size of the photolithography process.

6. The optical proximity correction method as described in claim 3, characterized in that, The first preset size is the limit size of the photolithography process; the second preset size is greater than or equal to the limit size of the photolithography process.

7. The optical proximity correction method as described in claim 2, characterized in that, The plurality of first metal line patterns include a plurality of first type metal line patterns; the plurality of second metal line patterns include a plurality of power rail patterns and a plurality of second type metal line patterns, wherein the width of the power rail patterns is greater than the width of the first type metal line patterns.

8. The optical proximity correction method as described in claim 7, characterized in that, Both the first reference pattern and the second reference pattern are the first type of metal line pattern, and the target reference pattern is the power rail pattern.

9. The optical proximity correction method as described in claim 1, characterized in that, The optical proximity correction method further includes: forming a cut-off layout using the cut-off pattern other than the pattern to be corrected in the merged pattern and the reference layout.

10. The optical proximity correction method as described in claim 1, characterized in that, Also includes: The first metal layer layout is composed of several first metal line patterns; The second metal layer layout is composed of several second metal line patterns.

11. The optical proximity correction method as described in claim 1, characterized in that, The method for obtaining the reference layout includes: providing an initial layout, the initial layout including a plurality of initial graphics; splitting the initial layout to obtain the reference layout, wherein the plurality of initial graphics are split into a plurality of first metal line graphics, a plurality of second metal line graphics and a plurality of cut-off graphics.

12. A photomask, characterized in that, The mask has a pattern formed using the optical proximity correction method as described in any one of claims 1 to 11.

13. A method for forming a semiconductor structure, characterized in that, include: A cutting mask is obtained, the cutting mask having a pattern formed by the optical proximity correction method as described in any one of claims 1 to 11; Provide substrate; A first metal layer is formed on the surface of the substrate. The first metal layer includes a plurality of first metal line structures. The plurality of first metal line structures are parallel to a third direction and arranged along a fourth direction. The third direction and the fourth direction are perpendicular to each other and parallel to the surface of the substrate. A pattern transfer layer and a photoresist layer are formed on the first metal layer; Using the cutting mask as a mask, the photoresist layer is patterned so that the pattern on the cutting mask is transferred to the photoresist layer; Using the patterned photoresist layer as a mask, the pattern transfer layer and the first metal layer are etched to form an opening in the first metal line structure, the opening penetrating the first metal line structure along the fourth direction; A sidewall material layer is formed within the opening, and the sidewall material layer within the opening serves as an isolation structure.

14. A method for forming a semiconductor structure, characterized in that, include: A cutting mask is obtained, the cutting mask having a pattern formed by the optical proximity correction method as described in claims 1 to 11; A substrate is provided, the surface of which has a second metal layer, the second metal layer including a plurality of second metal line structures and a plurality of grooves, the grooves being located between adjacent second metal line structures, the plurality of second metal line structures being parallel to a third direction and arranged along a fourth direction, the third direction and the fourth direction being perpendicular to each other; A pattern transfer layer and a photoresist layer on the pattern transfer layer are formed on the substrate surface and within the groove; Using the cutting mask as a mask, the photoresist layer is patterned so that the pattern on the cutting mask is transferred to the photoresist layer; Using the patterned photoresist layer as a mask, the pattern transfer layer is etched to form an opening in the pattern transfer layer within the groove; An isolation structure is formed within the opening.

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