Optical proximity correction method and system, mask, apparatus, and storage medium

Abstract

An optical proximity correction method and system, a mask, a device and a storage medium, the optical proximity correction method comprising: providing a design pattern; along the contour of the design pattern, obtaining a step edge as a broken line edge, the broken line edge being alternately composed of a plurality of first line segments extending along the extension direction of the broken line edge, and second line segments connecting adjacent first line segments; performing step elimination processing on the broken line edge of the design pattern, replacing the broken line edge with a straight line type reference edge with the same extension direction as the first line segment, and enclosing a reference pattern corresponding to the design pattern; setting a plurality of initial evaluation points on the reference edge; mapping the plurality of initial evaluation points to the broken line edge along a direction perpendicular to the reference edge to form evaluation points located on the broken line edge; performing optical proximity correction processing on the design pattern until the edge placement error at the evaluation points meets a preset condition to form a corrected pattern. The present application improves the accuracy of optical proximity correction.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and more particularly to an optical proximity correction method and system, a photomask, an apparatus, and a storage medium. Background Technology

[0002] As manufacturing processes become increasingly advanced and device dimensions shrink, the linewidth and spacing of the patterns in the photomasks used to create these devices also become smaller, while the types and shapes of the patterns become more complex. After photolithography, the difference between the pattern on the chip surface and the original photomask pattern increases. To avoid inconsistencies between the pattern on the chip and the photomask pattern caused by optical proximity effect, the current solution typically involves optical proximity correction (OPC) of the photomask pattern, followed by pattern transfer based on the corrected photomask pattern.

[0003] Some photomasks may contain stepped patterns, such as interconnect plug patterns in the plug layer of SRAM. Stepped edges in the pattern are difficult to handle in terms of merit points or sampling sites, often requiring special processing. Inadequate processing can lead to difficulty in controlling optical proximity correction, resulting in unreasonable pattern correction, a large discrepancy from the ideal linewidth, and a decrease in yield. Summary of the Invention

[0004] The problem solved by the embodiments of the present invention is to provide an optical proximity correction method and system, mask, device and storage medium to improve the effect of optical proximity correction.

[0005] To address the aforementioned problems, this invention provides an optical proximity correction method, comprising: providing a design graphic; obtaining a stepped edge along the contour of the design graphic as a polygonal edge, the polygonal edge being alternately composed of multiple first line segments extending along the extension direction of the polygonal edge and second line segments connecting adjacent first line segments; performing step elimination processing on the polygonal edge of the design graphic, replacing the polygonal edge with a straight reference edge having the same extension direction as the first line segments, and forming a reference graphic corresponding to the design graphic; establishing multiple initial evaluation points on the reference edge; mapping the multiple initial evaluation points onto the polygonal edge along a direction perpendicular to the reference edge, forming evaluation points located on the polygonal edge; performing optical proximity correction processing on the design graphic until the edge placement error at the evaluation point meets a preset condition, forming a corrected graphic.

[0006] Accordingly, this embodiment of the invention also provides an optical proximity correction system, comprising: a graphic providing module for providing a design graphic; a polygonal edge acquisition module for acquiring an edge with steps as a polygonal edge along the outline of the design graphic, wherein the polygonal edge is alternately composed of multiple first line segments extending along the extension direction of the polygonal edge and second line segments connecting adjacent first line segments; a reference edge forming module for performing step elimination processing on the polygonal edge of the design graphic, replacing the polygonal edge with a straight reference edge having the same extension direction as the first line segment, and forming a reference graphic corresponding to the design graphic; an initial evaluation point generation module for establishing multiple initial evaluation points on the reference edge; an evaluation point generation module for mapping the multiple initial evaluation points onto the polygonal edge along a direction perpendicular to the reference edge, forming evaluation points located on the polygonal edge; and an optical proximity correction module for performing optical proximity correction processing on the target graphic until the edge placement error at the evaluation point meets a preset condition, forming a corrected graphic.

[0007] Accordingly, embodiments of the present invention also provide a photomask, including a pattern obtained using the optical proximity correction method provided in embodiments of the present invention.

[0008] Accordingly, embodiments of the present invention also provide an apparatus including at least one memory and at least one processor, wherein the memory stores one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the optical proximity correction method provided in embodiments of the present invention.

[0009] Accordingly, embodiments of the present invention also provide a storage medium storing one or more computer instructions, which are used to implement the optical proximity correction method provided in embodiments of the present invention.

[0010] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0011] In the optical proximity correction method provided in this embodiment of the invention, the broken edge of the design pattern is subjected to step elimination processing, and the broken edge is replaced with a straight reference edge with the same extension direction as the first line segment, forming a reference pattern corresponding to the design pattern. In this embodiment of the invention, when forming a straight reference edge corresponding to the broken edge of the design pattern, the initial evaluation points are set with the straight reference edge as the reference. The initial evaluation points are set relatively evenly across the entire reference edge. Correspondingly, the evaluation points mapped onto the broken edge are also set relatively evenly across the entire broken edge. Compared with the scheme of directly setting evaluation points on the broken edge, this embodiment of the invention is beneficial to avoid the correction model being affected by... By identifying the step positions of the broken line edges and mistaking the first line segments for different edges, and establishing evaluation points for each first line segment, this invention helps avoid the problems of uneven evaluation point placement and the easy loss of evaluation points near the step positions. Furthermore, this embodiment of the invention saves time that would otherwise be spent on special processing near the step positions to prevent uneven evaluation point placement and the loss of evaluation points near the step positions, thus improving the efficiency of optical proximity correction. Moreover, by setting evaluation points relatively evenly across the broken line edges, it is beneficial to control the edge placement error at the evaluation points, making the correction of the broken line edges more accurate, thereby improving the accuracy of the optical proximity correction. Attached Figure Description

[0012] Figure 1 This is a flowchart of an optical proximity correction method;

[0013] Figures 2 to 3 This is a schematic diagram of an optical proximity correction method;

[0014] Figure 4 This is a flowchart of an embodiment of the optical proximity correction method of the present invention;

[0015] Figures 5 to 10 This is a schematic diagram of each step in one embodiment of the optical proximity correction method of the present invention;

[0016] Figure 11 This is a functional block diagram of an embodiment of the optical proximity correction system of the present invention;

[0017] Figure 12 This is a hardware structure diagram of an embodiment of the device provided by the present invention. Detailed Implementation

[0018] The effectiveness of optical proximity correction needs improvement. This paper analyzes the reasons why the effectiveness of optical proximity correction needs further improvement, using one such method as an example.

[0019] Figure 1 This is a flowchart of an optical proximity correction method. (Refer to reference.) Figures 2 to 3The diagram shows the optical proximity correction method, which includes:

[0020] refer to Figure 2 Step s1: Provide design drawing 10, which includes a step (e.g., Figure 2 The broken line edge 10j (shown by the dashed circle in the middle) is a polygonal line.

[0021] Reference Figure 2 and Figure 3 Step s2: Establish evaluation point P on the edge of design graphic 10.

[0022] Continue to refer to Figure 2 and Figure 3 Step s3: Perform optical proximity correction processing on the design graphic 10 until the edge placement error (EPE) at the evaluation point P meets the preset conditions, thus forming the corrected graphic.

[0023] Because the design graphic 10 includes a broken line edge 10j with steps, when setting the evaluation point P, the correction model, due to identifying the step position of the broken line edge 10j, interrupted the broken line edge 10j at the step, mistakenly dividing the broken line edge 10j into different edges, and setting the evaluation point P separately for each interrupted part of the broken broken line edge 10j, such as... Figure 2 As shown, this can easily lead to uneven distribution of evaluation points P, and the evaluation points P may be missing near the step.

[0024] In particular, during the optical proximity correction process, an ideal simulation pattern 20 corresponding to the design pattern 10 is usually formed as a reference for measuring the edge placement error at the evaluation point P. At this time, the evaluation point P is usually set near the middle of an edge. Therefore, after the broken line edge 10j is broken, the evaluation point P is set for each broken part of the broken line edge 10j, which makes it easier to cause uneven setting of the evaluation point P and the problem that the evaluation point P is easily missing near the step position.

[0025] refer to Figure 3 In order to establish a suitable evaluation point P at the broken line edge 10j, the broken line edge 10j is selected for special processing. It is necessary to make corresponding evaluation point P special settings for each design graphic 10. For example, the evaluation point P is set at a distance of 10%, 30%, and 50% of the total length of the broken part of the broken line edge at a distance of 10% from the step. Therefore, the special processing steps are relatively cumbersome. At the same time, different processing is required for different design graphics 10. Furthermore, the evaluation point P established after special processing is difficult to be evenly and appropriately distributed, making it difficult to achieve a good optical proximity correction effect.

[0026] To address the aforementioned technical problem, embodiments of the present invention provide an optical proximity correction method. (Reference) Figure 4 The flowchart of an embodiment of the optical proximity correction method of the present invention is shown.

[0027] In this embodiment, the optical proximity correction method includes the following basic steps:

[0028] Step S1: Provide design graphics;

[0029] Step S2: Along the outline of the design graphic, obtain the edge with steps as the broken line edge. The broken line edge is composed of multiple first line segments extending along the extension direction of the broken line edge and second line segments connecting adjacent first line segments alternately.

[0030] Step S3: Perform step elimination processing on the broken line edge of the design graphic, replace the broken line edge with a straight reference edge with the same extension direction as the first line segment, and form a reference graphic corresponding to the design graphic;

[0031] Step S4: Establish multiple initial evaluation points on the reference edge;

[0032] Step S5: Map the multiple initial evaluation points onto the polyline edge along a direction perpendicular to the reference edge to form evaluation points located on the polyline edge;

[0033] Step S6: Perform optical proximity correction processing on the design graphic until the edge placement error at the evaluation point meets the preset conditions, thus forming the corrected graphic.

[0034] In this embodiment of the invention, a straight reference edge is formed corresponding to the polygonal edge of the design graphic. When setting initial evaluation points, the straight reference edge is used as a reference. The initial evaluation points are set relatively evenly across the reference edge. Correspondingly, the evaluation points mapped onto the polygonal edge are also set relatively evenly across the polygonal edge. Compared to the scheme of setting evaluation points directly on the polygonal edge, this embodiment of the invention helps to avoid the problem that the correction model might mistakenly identify the first line segment as a different edge due to the step position of the polygonal edge, and set evaluation points for each first line segment separately. This helps to avoid the problems of uneven evaluation point setting and the easy loss of evaluation points near the step position. At the same time, this embodiment of the invention also saves the time of performing special processing near the step position to prevent uneven evaluation point setting and the loss of evaluation points near the step position, thus improving the efficiency of optical proximity correction processing. Moreover, setting evaluation points relatively evenly across the polygonal edge helps to control the edge placement error at the evaluation points, making the correction of the polygonal edge more accurate, thereby improving the accuracy of optical proximity correction.

[0035] To make the above-mentioned objects, features and advantages of the embodiments of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] Figures 5 to 10 This is a schematic diagram of each step in one embodiment of the optical proximity correction method of the present invention.

[0037] refer to Figure 5 Step S1: Provide design graphics 100.

[0038] Design pattern 100 is a pattern that needs to be transferred to the wafer. After optical proximity correction is performed on design pattern 100, the obtained pattern is used to make a mask, and then photolithography is performed on the mask to form the corresponding mask pattern on the wafer.

[0039] In this embodiment, the design pattern 100 includes an interconnect plug pattern (share CT).

[0040] Interconnect plug patterns are used to form interconnect plug structures on a wafer. In SRAM devices, interconnect plug structures are typically used as leads for source and drain doped layers to electrically bring out the source and drain doped layers or to electrically interconnect the source and drain doped layers.

[0041] Continue to refer to Figure 5 Execute step S2: Along the outline of design graphic 100, obtain the step (e.g., Figure 5 The edge (shown by the dashed circle in the middle) is used as the broken line edge 100j, and the broken line edge 100j is composed of multiple extension directions along the broken line edge 100j (such as...). Figure 5 The first line segment 100a (as shown in the X direction) extends alternately, and the second line segment 100b connecting the adjacent first line segment 100a is formed.

[0042] Obtain the polyline edge 100j, which will be used as the object for subsequent step elimination processing.

[0043] In this embodiment, the design pattern 100 includes an interconnect plug pattern. The edges of the interconnect plug pattern typically include jog points or nub points, which are stepped polygonal edges 100j. Therefore, this embodiment is more suitable for modifying the interconnect plug pattern.

[0044] In this embodiment, the ratio of the length of the second line segment 100b to the length of the first line segment 100a is less than or equal to 1:3. Therefore, while meeting the design requirements, the length of the second line segment 100b is relatively small compared to the first line segment 100a, and is almost negligible. Thus, the broken line edge 100j should be treated as an independent edge for optical proximity correction.

[0045] In this embodiment, before performing optical proximity correction processing on the design graphic 100, the method further includes: segmenting the edges of the design graphic 100 to obtain a plurality of sequentially connected third line segments 100c.

[0046] For ease of illustration, Figure 5 The endpoint of the third line segment 100c is marked with a solid dot.

[0047] In the subsequent optical proximity correction process for the design graphic 100, to reduce the arbitrariness of edge movement, the position of line segments is adjusted (e.g., line segments are translated) to reduce edge placement errors. In this embodiment, the position of the third line segment 100c is subsequently adjusted for optical proximity correction.

[0048] In this embodiment, the edges corresponding to each side of the design graphic 100 are divided into multiple first line segments 100c. Since in this embodiment, other edges besides the polyline edge 100j are not adjusted, therefore... Figure 5 The division of other edges is not shown in the text.

[0049] Reference Figures 6 to 7 Step S3: Perform step elimination processing on the broken line edge 100j of the design graphic 100, replace the broken line edge 100j with a straight line reference edge 110j that extends in the same direction as the first line segment 100a, and form a reference graphic 110 corresponding to the design graphic 100.

[0050] In this embodiment, a straight reference edge 110j is formed corresponding to the polygonal edge 100j of the design graphic 100. When setting initial evaluation points later, the straight reference edge 110j is used as a reference, and the initial evaluation points are set relatively evenly across the entire reference edge 110j. Correspondingly, the evaluation points mapped onto the polygonal edge 100j are also set relatively evenly across the entire polygonal edge 100j. Compared to the scheme of directly setting evaluation points on the polygonal edge, this embodiment helps avoid the correction model mistaking the first line segment 100a for a different edge due to identifying the step position of the polygonal edge 100j, and thus addresses each... This embodiment addresses the issue of setting evaluation points for the first line segment 100a, thereby avoiding the problems of uneven evaluation point setting and the easy loss of evaluation points near the step position. At the same time, this embodiment also saves the time required for special processing near the step position to prevent uneven evaluation point setting and the loss of evaluation points near the step position, thus improving the efficiency of optical proximity correction processing. Moreover, the relatively uniform setting of evaluation points for the broken line edge 100j as a whole helps to control the edge placement error at the evaluation points, making the correction of the broken line edge 100j more accurate, thereby improving the accuracy of optical proximity correction.

[0051] It should be noted that the broken line edge 100j is replaced with a straight reference edge 110j that extends in the same direction as the first line segment 100a, and together with the other edges of the design pattern 100, they form a reference pattern 110. When the reference edge 110j is formed, if the reference edge 110j does not intersect with the other edges of the design pattern 100, the other edges of the design pattern 100 are extended to intersect with the reference edge 110j to form a closed reference pattern 110.

[0052] For clarity of illustration, Figures 6 to 9 The third line segment 100c is not shown in the text.

[0053] Specifically, refer to Figure 6 The steps for eliminating steps on the broken line edge 100j of the design graphic 100 include: selecting any first line segment 100a as the positioning line segment in the broken line edge 100j.

[0054] The positioning line segment is used to set the position of the formed reference edge 110j.

[0055] If any of the first line segments 100a is selected as the positioning line segment, then in the extension direction perpendicular to the first line segment 100a, the formation position of the reference edge 110j will not exceed the area occupied by the broken line edge 100j in the extension direction perpendicular to the first line segment 100a. As a result, the difference between the formed reference graphic 110 and the design graphic 100 is small. Therefore, the initial evaluation point established based on the reference graphic 110 can be mapped as the evaluation point of the design graphic 100.

[0056] In this embodiment, the first line segment 100a located on the outermost side of the design graphic 100 is selected as the positioning line segment.

[0057] If the first line segment 100a located on the outermost side of the design graphic 100 is selected as the positioning line segment, the resulting reference graphic 110 can include the design graphic 100. Each side of the reference graphic 110 can cover each side of the design graphic 100. Thus, when the graphic difference between the reference graphic 110 and the design graphic 100 is small, the complete length of each side of the design graphic 100 can be taken into account in the subsequent process of setting the initial evaluation point based on the reference graphic 110.

[0058] refer to Figure 7 The step of eliminating steps on the broken line edge 100j of the design graphic 100 further includes: translating the remaining first line segments 100a in the broken line edge 100j along a direction perpendicular to the first line segment 100a to a position flush with the positioning line segment, and connecting the translated first line segment 100a with the positioning line segment to form a straight reference edge 110j.

[0059] For clarity of illustration, Figures 7 to 9The design graphic 100 is represented by a dashed line.

[0060] By translating to form a reference edge 110j that connects the first line segment 100a with the positioning line segment, it is possible to obtain a straight reference edge 110j while ensuring that the reference edge 110j maintains the original length of the polyline edge 100j. Thus, the initial evaluation point set for the reference edge 110j can be mapped as the evaluation point of the polyline edge 110j.

[0061] In this embodiment, in the step of eliminating the steps of the broken edge 100j of the design graphic 100, the shape of the reference graphic 110 is a square or a rectangle.

[0062] If the shape of the reference figure 110 is a square or a rectangle, then all the sides of the reference figure 110 are straight lines, which facilitates the establishment of initial evaluation points based on the reference figure 110.

[0063] Continue to refer to Figure 6 Before setting multiple initial evaluation points on reference edge 110j, the process also includes: setting the design graphic 100 based on experience to obtain the ideal simulation graphic 200.

[0064] The ideal simulation pattern 200 is an ideal exposure pattern on the wafer after optical proximity correction processing. The ideal simulation pattern 200 is also used as a reference for the edge placement error of the exposure pattern obtained by photolithography simulation.

[0065] In actual exposure and development processes, a corner rounding effect often occurs. This means that right-angled corners of a pattern are typically exposed as rounded corners. Therefore, the actual pattern formed on the wafer from the designed pattern 100 has rounded corners. In this embodiment, the ideal simulated pattern 200 with rounded corners is used as a reference for edge placement error, which is closer to the actual process. When subsequently converging edge placement errors, less time and cost are required to converge the edge placement errors at the corners. This ensures the effectiveness of optical proximity correction in practical applications while improving correction efficiency and avoiding unnecessary time and cost waste.

[0066] In this embodiment, the step of setting the design graphic 100 based on experience to obtain the ideal simulation graphic 200 includes: rounding the corners of the adjacent sides of the design graphic 100, wherein the lengths of the two ends of the broken line edge 100j used for rounding are the first length L1 and the second length L2, respectively.

[0067] Based on actual exposure experience and the length of each side of the design graphic 100, the length of the corners of the adjacent sides of the design graphic 100 for rounding is set. The corners of the adjacent sides of the design graphic 100 are rounded to form an ideal simulation graphic 200. The length used for rounding is the part that does not need to be converged for edge placement error in the future.

[0068] In this embodiment, the lengths used for rounding at both ends of the broken edge 100j are the first length L1 and the second length L2, respectively. Therefore, the portions of the first length L1 and the second length L2 at both ends of the broken edge 100j do not need to undergo edge placement error convergence processing.

[0069] In the actual exposure and development process, the jog points and nub points of the pattern are usually exposed as smooth arcs. That is to say, the step in the design pattern 100 is actually a smooth arc on the wafer. Therefore, the step of obtaining the ideal simulated pattern 200 also includes: smoothing the step in the design pattern 100. The ideal simulated pattern 200 obtained can ensure the effect of optical proximity correction in actual application, and at the same time, it is conducive to improving the feasibility of subsequent edge placement error convergence.

[0070] It should be noted that the first length L1 should not be too large or too small. If the first length L1 is too large, the length of one end of the broken edge 100j used for rounding will be too large, resulting in an excessively large rounded portion of the formed ideal simulation pattern 200. This can easily lead to a large discrepancy between the ideal simulation pattern 200 and the design pattern 100. Since the ideal simulation pattern 200 will also serve as a reference for edge placement error, this can negatively impact the correction effect of optical proximity correction. Furthermore, if the length of one end of the broken edge 100j used for rounding is too large, the remaining length of the broken edge 100j will be too small. In other words, the portion of the broken edge 100j used for edge placement error convergence will be too small, making accurate optical proximity correction difficult. Conversely, if the first length L1 is too small, the length of one end of the broken edge 100j used for rounding will be too small, resulting in an excessively small rounded portion of the formed ideal simulation pattern 200. When the ideal simulation pattern 200 serves as a reference for edge placement error, the convergence standard for edge placement error will be too stringent, leading to difficulty in converging the edge placement error. This also increases the correction processing time and wastes unnecessary costs. Therefore, in this embodiment, the first length L1 is set to an appropriate value based on experience.

[0071] Similar to the first length L1, the second length L2 is set to an appropriate value based on experience.

[0072] refer to Figure 8 Step S4: Establish multiple initial evaluation points P0 on reference edge 110j.

[0073] The initial evaluation point P0 is used as a reference for the subsequent evaluation points in the design drawing 100.

[0074] In this embodiment, the distance between adjacent initial evaluation points P0 is equal.

[0075] If the spacing between adjacent initial evaluation points P0 is equal, the initial evaluation points P0 are set up relatively evenly. Correspondingly, the evaluation points mapped by the subsequent initial evaluation points are also relatively evenly distributed. As a result, when the edge placement error convergence processing is performed at the evaluation points, the distribution of evaluation points is relatively even, making the correction of the broken line edge 100j more accurate.

[0076] Specifically, in the step of setting up multiple initial evaluation points P0 on the reference edge 110j, a first length L1 and a second length L2 are respectively cut off at both ends of the reference edge 110j, and multiple initial evaluation points P0 are set on the remaining length of the reference edge 110j.

[0077] In this embodiment, the ideal simulated pattern 200 serves as a reference benchmark for the edge placement error of the exposure pattern obtained by photolithography simulation. The portions of the first length L1 and the second length L2 at both ends of the broken edge 100j do not require edge placement error convergence processing. That is, evaluation points are subsequently set up on the remaining length portion of the broken edge 100j, and the evaluation points are mapped from the initial evaluation points P0. Therefore, in this embodiment, the first length L1 and the second length L2 are respectively cut off at both ends of the reference edge 110j, and multiple initial evaluation points P0 only need to be set up on the remaining length of the reference edge 110j.

[0078] In this embodiment, the step of setting multiple initial evaluation points P0 on the remaining length of the reference edge 110j includes: dividing the remaining length of the reference edge 110j into multiple fourth line segments 100d; and selecting the midpoint of each fourth line segment 100d as the initial evaluation point P0.

[0079] For ease of illustration, Figure 8 The endpoint of the fourth line segment 100d is marked with a solid dot.

[0080] The remaining length of the reference edge 110j is divided into multiple fourth line segments 100d. The midpoint of each fourth line segment 100d is selected as the initial evaluation point P0. This allows for the acquisition of uniform initial evaluation points P0, as well as initial evaluation points P0 located at the center of each fourth line segment 100d. The initial evaluation points P0 are in a uniform and unbiased position relative to the remaining length of the reference edge 110j, ensuring that subsequent evaluation points are also in a uniform and unbiased position on the remaining length of the polygonal edge 100j, further making the correction of the polygonal edge 100j more accurate.

[0081] It should be noted that the length of the fourth line segment 100d should not be too large or too small. If the length of the fourth line segment 100d is too large, there will be too few fourth line segments 100d, resulting in too few initial evaluation points P0 and consequently too few subsequent evaluation points. This makes it difficult to achieve overall convergence of the polygonal edge 100j through edge placement error convergence processing at the evaluation points, thus affecting the results of the optical proximity correction processing. If the length of the fourth line segment 100d is too small, there will be too many fourth line segments 100d, resulting in too many initial evaluation points P0 and consequently too many subsequent evaluation points. This increases the number of unnecessary convergence points during edge placement error convergence processing at the evaluation points, making edge placement error convergence more difficult and increasing unnecessary correction processing time, thus affecting the progress of the optical proximity correction processing. Therefore, in this embodiment, the length of the fourth line segment 100d is set according to the size of the remaining length of the reference edge 110j, and an appropriate value is set based on experience.

[0082] Continue to refer to Figure 8 In this embodiment, the step of setting up multiple initial evaluation points P0 on the reference edge 110j further includes setting up multiple initial evaluation points P0 on other edges of the reference graphic 110.

[0083] In this embodiment, the reference graphic 110 and the design graphic 100 have very little difference in shape. Therefore, the initial evaluation points P0 corresponding to the evaluation points required for each side of the design graphic 100 can be set on the reference graphic 110 and then mapped uniformly. This unifies the steps of setting evaluation points, making the optical proximity correction process less complicated and easier to operate. Furthermore, since the reference graphic 110 is a rectangle or a square, the operation of setting the initial evaluation points P0 on the reference graphic 110 is even simpler.

[0084] refer to Figure 9 Execute step S5: Move multiple initial evaluation points P0 along a direction perpendicular to the reference edge 110j (e.g., ... Figure 9 The point P is mapped onto the broken line edge 100j (as shown in the Y direction) to form the evaluation point P located on the broken line edge 100j.

[0085] Evaluation point P is used as the specific location for comparing the difference between the simulated graphic and the target simulated graphic 200 in the optical proximity correction process, thereby obtaining the edge placement error used to determine whether the optical proximity correction is completed.

[0086] In this embodiment, the step of mapping multiple initial evaluation points P0 onto the broken line edge 100j along a direction perpendicular to the reference edge 110j to form an evaluation point P located on the broken line edge 100j further includes: mapping multiple initial evaluation points P0 established on other edges of the reference graphic 110 onto the design graphic 100 along a direction perpendicular to the corresponding other edges to form an evaluation point P located on the design graphic 100.

[0087] In this embodiment, by using the initial evaluation point P0 established by the reference graphic 110, the evaluation points of each side of the design graphic 100 are obtained. This avoids the problem of uneven establishment of evaluation points P and the easy loss of evaluation points P near the step position, while improving the efficiency of the establishment of evaluation points P, thereby improving the efficiency of optical proximity correction processing.

[0088] refer to Figure 10 Step S6: Perform optical proximity correction processing on the design graphic 100 until the edge placement error at the evaluation point P meets the preset conditions, forming the corrected graphic (not shown).

[0089] In this embodiment, model-based optical proximity correction (MB-OPC) is used to perform optical proximity correction on the design pattern 100. During the correction process, an optical model and a photoresist photochemical reaction model are used to calculate the simulated pattern of the design pattern 100 after exposure. The model-based optical proximity correction compares the exposed simulated pattern with the outline of the target simulated pattern 200, and the difference between them is called edge placement error (EPE). Edge placement error is an indicator used to measure the quality of correction. The smaller the edge placement error, the closer the exposed pattern is to the target pattern 100.

[0090] In other embodiments, rule-based optical proximity correction (OPC) or a combination of model-based and rule-based optical proximity correction can be used for optical proximity correction. In still other embodiments, other suitable optical proximity correction methods can be selected.

[0091] In this embodiment, the edge position error at evaluation point P is calculated, and optical proximity correction is performed by converging the edge position error at evaluation point P.

[0092] In this embodiment, in the step of performing optical proximity correction processing on the design graphic 100 until the edge placement error at evaluation point P meets the preset condition, the preset condition is that the absolute value of the edge placement error is less than or equal to a preset value. The preset value should not be too large or too small. If the preset value is too large, even when the absolute value of the edge placement error at evaluation point P is less than or equal to the preset value, the edge placement error is still large and has not converged, making it difficult to achieve the correction effect of optical proximity correction. If the preset value is too small, the correction accuracy of the optical proximity correction processing is raised to an unnecessarily high level, the requirement for edge placement error convergence is too stringent, the computational load of the optical proximity correction processing is increased, and the correction of the optical proximity correction processing becomes difficult. Therefore, in this embodiment, the preset value is set appropriately based on experience.

[0093] In this embodiment, the step of performing optical proximity correction processing on the design graphic 100 includes: adjusting the position of the third line segment 100c where the evaluation point P is located.

[0094] To reduce the arbitrariness of edge movement, edge placement errors are reduced by adjusting the position of line segments (e.g., translating line segments). In this embodiment, optical proximity correction is performed by adjusting the position of the third line segment 100c where the evaluation point P is located.

[0095] Specifically, please refer to Figure 10 The steps for optical proximity correction processing of the design graphic 100 include: performing one or more correction operations until the edge placement error at the evaluation point P meets the preset conditions. The correction operations include: performing simulated exposure on the design graphic 100 to obtain a simulated graphic 210.

[0096] The simulated graphic 210 is used to compare with the target simulated graphic 200 to obtain the edge placement error corresponding to the simulated graphic 210.

[0097] Continue to refer to Figure 10 Calculate the edge placement error between the simulated graphic 210 and the ideal simulated graphic 200 at the evaluation point P.

[0098] Correspondingly, at evaluation point P, if the edge placement error of the simulated graphic 210 is greater than 0, it means that the simulated graphic 210 is located outside the target simulated graphic 200; if the edge placement error of the simulated graphic 210 is less than 0, it means that the simulated graphic 210 is located inside the target simulated graphic 200; and if the edge placement error of the simulated graphic 210 is equal to 0, it means that the simulated graphic 210 is located on the target simulated graphic 200.

[0099] In other embodiments, a graphic with a certain bias based on the design graphic can be formed as an ideal graphic, thereby allowing the calculation of the edge placement error between the simulated graphic and the ideal graphic at the location of the evaluation point.

[0100] Continue to refer to Figure 10 Based on the edge placement error, adjust the position of the third line segment 100c where the evaluation point P is located.

[0101] Specifically, along the direction perpendicular to the third line segment 100c, when the edge placement error is greater than 0, the corresponding third line segment 100c is moved inward into the design graphic 100; when the edge placement error is less than 0, the corresponding third line segment 100c is moved outward from the design graphic 100; when the edge placement error is equal to 0, the position of the corresponding third line segment 100c is maintained, that is, the third line segment 100c is not moved.

[0102] It should be noted that after a correction operation, in the next correction operation of the iterative cycle, the design pattern 100 after moving the third line segment 100c in the previous correction operation is used as the design pattern 100 for simulated exposure. In other words, the design pattern 100 obtained after adjusting the position of the third line segment 100c is used as the design pattern 100 for simulated exposure in the next correction operation.

[0103] When the edge placement error of the evaluation point P meets the preset conditions, the design graphic 100 after adjusting the position of the third line segment 100c is used as the corrected graphic.

[0104] Accordingly, the present invention also provides an optical proximity correction system. Figure 11 This is a functional block diagram of an embodiment of the optical proximity correction system of the present invention.

[0105] In this embodiment, the optical proximity correction system 50 includes: a graphic providing module 501 for providing a design graphic; a polygonal edge acquisition module 502 for acquiring an edge with steps along the outline of the design graphic as a polygonal edge, wherein the polygonal edge is alternately composed of multiple first line segments extending along the extension direction of the polygonal edge and second line segments connecting adjacent first line segments; a reference edge forming module 503 for performing step elimination processing on the polygonal edge of the design graphic, replacing the polygonal edge with a straight reference edge with the same extension direction as the first line segment, and forming a reference graphic corresponding to the design graphic; an initial evaluation point generation module 504 for establishing multiple initial evaluation points on the reference edge; an evaluation point generation module 505 for mapping the multiple initial evaluation points onto the polygonal edge along a direction perpendicular to the reference edge, forming evaluation points located on the polygonal edge; and an optical proximity correction module 506 for performing optical proximity correction processing on the target graphic until the edge placement error at the evaluation point meets a preset condition, forming a corrected graphic.

[0106] The design pattern provided by the pattern providing module 501 is the pattern that needs to be transferred to the wafer. After optical proximity correction is performed on the design pattern, the obtained pattern is used to make a mask, and then the photolithography process is performed using the mask to form the corresponding mask pattern on the wafer.

[0107] In this embodiment, the design pattern includes interconnect plug patterns.

[0108] Interconnect plug patterns are used to form interconnect plug structures on a wafer. Typically, interconnect plug structures are formed in SRAM devices to serve as leads for source and drain doped layers, either to electrically bring out the source and drain doped layers or to electrically interconnect the source and drain doped layers.

[0109] The polyline edge acquisition module 502 is used to acquire the edge with steps as a polyline edge along the outline of the design graphic. The polyline edge is composed of multiple first line segments extending along the extension direction of the polyline edge and second line segments connecting adjacent first line segments alternately.

[0110] Obtain the polyline edge, which will be used as the object for subsequent step elimination processing.

[0111] In this embodiment, the design pattern includes an interconnect plug pattern. The edges of the interconnect plug pattern usually include jog points or nub points, which are broken line edges with steps. Therefore, this embodiment is more suitable for modifying the interconnect plug pattern.

[0112] In this embodiment, the ratio of the length of the second line segment to the length of the first line segment is less than or equal to 1:3. Therefore, while the design of the polygonal edge meets the design requirements, the length of the second line segment is relatively small, especially compared to the first line segment, the length of the second line segment is almost negligible. Thus, the polygonal edge should be treated as an independent edge for optical proximity correction.

[0113] In this embodiment, before performing optical proximity correction processing on the design graphic, the method further includes: segmenting the edges of the design graphic to obtain multiple sequentially connected third line segments.

[0114] In the subsequent optical proximity correction process for the design graphic, to reduce the arbitrariness of edge movement, the position of line segments is adjusted (e.g., line segment translation) to reduce edge placement errors. In this embodiment, the position of the third line segment is subsequently adjusted for optical proximity correction.

[0115] In this embodiment, the edges corresponding to each edge of the design graphic are divided into multiple first line segments.

[0116] The reference edge forming module 503 is used to perform step elimination processing on the polyline edge of the design graphic, replace the polyline edge with a straight reference edge that extends in the same direction as the first line segment, and form a reference graphic corresponding to the design graphic.

[0117] In this embodiment, a straight reference edge is formed corresponding to the polygonal edge of the design graphic. When setting initial evaluation points later, the straight reference edge is used as the benchmark, and the initial evaluation points are set relatively evenly across the reference edge. Correspondingly, the evaluation points mapped onto the polygonal edge are also set relatively evenly across the polygonal edge. Compared with the scheme of setting evaluation points directly on the polygonal edge, this embodiment helps to avoid the problem that the correction model might mistakenly identify the first line segment as a different edge due to the step position of the polygonal edge, and set evaluation points for each first line segment separately. This helps to avoid the problems of uneven evaluation point setting and the easy absence of evaluation points near the step position. At the same time, this embodiment also saves the time of performing special processing near the step position to prevent uneven evaluation point setting and the absence of evaluation points near the step position, thus improving the efficiency of optical proximity correction processing. Moreover, setting evaluation points relatively evenly across the polygonal edge helps to control the edge placement error at the evaluation points, making the correction of the polygonal edge more accurate, thereby improving the accuracy of optical proximity correction.

[0118] It should be noted that the broken line edge is replaced with a straight reference edge that extends in the same direction as the first line segment, and together with the other edges of the design graphic, they form a reference graphic. When the reference edge is formed, if it does not intersect with the other edges of the design graphic, the other edges of the design graphic are extended to intersect with the reference edge to form a closed reference graphic.

[0119] Specifically, within the broken line edge, select any first line segment as the positioning line segment.

[0120] Positioning segments are used to define the position of the reference edge to be formed.

[0121] If any first line segment is selected as the positioning line segment, the position of the reference edge in the direction perpendicular to the extension of the first line segment will not exceed the area occupied by the broken line edge in the direction perpendicular to the extension of the first line segment. As a result, the difference between the reference graphic and the design graphic is small. Therefore, the initial evaluation point established based on the reference graphic can be mapped as the evaluation point of the design graphic.

[0122] In this embodiment, the first line segment located on the outermost side of the design graphic is selected as the positioning line segment.

[0123] If the first line segment located on the outermost side of the design graphic is selected as the positioning line segment, the resulting reference graphic can include the design graphic. Each side of the reference graphic can cover each side of the design graphic. Thus, when the difference between the reference graphic and the design graphic is small, the complete length of each side of the design graphic can be taken into account in the subsequent process of setting initial evaluation points based on the reference graphic.

[0124] In this embodiment, the remaining first line segments in the broken line edge are all translated in a direction perpendicular to the first line segment to a position flush with the positioning line segment. The translated first line segments are connected with the positioning line segment to form a straight reference edge.

[0125] By translating to form a reference edge connecting the first line segment and the positioning line segment, it is possible to obtain a straight reference edge while ensuring that the reference edge maintains the original length of the polyline edge. Thus, the initial evaluation point set for the reference edge can be mapped as the evaluation point of the polyline edge.

[0126] In this embodiment, in the step of eliminating the steps on the broken edge of the design graphic, the shape of the reference graphic is a square or a rectangle.

[0127] If the reference figure is square or rectangular, then all its sides are straight lines, which facilitates the establishment of initial evaluation points based on the reference figure.

[0128] In this embodiment, the method further includes: setting the design graphic based on experience to obtain an ideal simulation graphic.

[0129] The ideal simulation pattern is the ideal exposure pattern on the wafer after optical proximity correction processing. The ideal simulation pattern is also used as a reference for the edge placement error of the exposure pattern obtained by photolithography simulation.

[0130] In actual exposure and development processes, a smoothing effect often occurs at corners. This means that right-angled corners of a pattern are typically exposed as rounded corners. Therefore, the actual pattern formed on the wafer has rounded corners. In this embodiment, an ideal simulated pattern with rounded corners is used as a reference for edge placement error, which is closer to the actual process. Subsequent edge placement error convergence does not require significant time and cost to converge the edge placement error at the corners. This ensures the effectiveness of optical proximity correction in practical applications while improving correction efficiency and avoiding unnecessary time and cost waste.

[0131] In this embodiment, the step of setting the design graphic based on experience to obtain an ideal simulated graphic includes: rounding the corners of adjacent sides of the design graphic, wherein the lengths of the two ends of the broken line edge used for rounding are the first length L1 and the second length L2, respectively.

[0132] Based on actual exposure experience and the length of each side of the design graphic, the length for rounding the corners of adjacent sides of the design graphic is set. The corners of adjacent sides of the design graphic are rounded to form an ideal simulation graphic. The length used for rounding is the part that does not need to be converged for edge placement error in the later stage.

[0133] In this embodiment, the lengths used for rounding the corners at both ends of the broken line edge are the first length L1 and the second length L2, respectively. Therefore, the portions of the first length L1 and the second length L2 at both ends of the broken line edge do not need to undergo edge placement error convergence processing.

[0134] In the actual exposure and development process, the jog points and nub points of the pattern are usually exposed as smooth arcs. That is to say, the steps in the design pattern are actually smooth arcs on the wafer. Therefore, the steps to obtain the ideal simulated pattern also include: smoothing the steps of the design pattern. The ideal simulated pattern obtained can ensure the effect of optical proximity correction in actual applications, and at the same time, it is conducive to improving the feasibility of subsequent edge placement error convergence.

[0135] It should be noted that the first length L1 should not be too large or too small. If the first length L1 is too large, the length used for rounding at one end of the polygonal edge is too large, resulting in an excessively large rounded portion of the ideal simulated graphic. This can easily lead to a large discrepancy between the ideal simulated graphic and the designed graphic. Since the ideal simulated graphic will subsequently serve as a reference for edge placement error, this can negatively impact the correction effect of optical proximity correction. Furthermore, if the length used for rounding at one end of the polygonal edge is too large, the remaining length of the polygonal edge will be too small. In other words, the portion of the polygonal edge used for edge placement error convergence will be insufficient, making accurate optical proximity correction difficult. If the first length L1 is too small, the length used for rounding at one end of the polygonal edge is too small, resulting in an excessively small rounded portion of the ideal simulated graphic. When the ideal simulated graphic serves as a reference for edge placement error, the convergence standard for edge placement error may become overly stringent, leading to difficulties in convergence and increasing correction processing time and unnecessary cost waste. Therefore, in this embodiment, the first length L1 is set to an appropriate value based on experience.

[0136] Similar to the first length L1, the second length L2 is set to an appropriate value based on experience.

[0137] The initial evaluation point generation module 504 is used to establish multiple initial evaluation points P0 on the reference edge.

[0138] The initial evaluation point P0 is used as a reference for the evaluation points in the subsequent formation of the design drawings.

[0139] In this embodiment, the distance between adjacent initial evaluation points P0 is equal.

[0140] If the distance between adjacent initial evaluation points P0 is equal, the initial evaluation points P0 are set up relatively evenly. Correspondingly, the evaluation points mapped by the subsequent initial evaluation points are also relatively evenly distributed. Therefore, when the edge placement error convergence processing is performed at the evaluation points, the distribution of evaluation points is relatively even, making the correction of the broken line edge more accurate.

[0141] Specifically, in the step of setting up multiple initial evaluation points P0 on the reference edge, a first length L1 and a second length L2 are respectively cut off at both ends of the reference edge, and multiple initial evaluation points P0 are set on the remaining length of the reference edge.

[0142] In this embodiment, the ideal simulated pattern serves as a reference benchmark for the edge placement error of the exposure pattern obtained by photolithography simulation. The portions of the first length L1 and the second length L2 at both ends of the broken edge do not require edge placement error convergence processing. That is, evaluation points are subsequently set up on the remaining length portion of the broken edge, and the evaluation points are mapped from the initial evaluation point P0. Therefore, in this embodiment, the first length L1 and the second length L2 are respectively cut off at both ends of the reference edge, and multiple initial evaluation points P0 only need to be set up on the remaining length of the reference edge.

[0143] In this embodiment, the remaining length of the reference edge is divided into multiple fourth line segments; the midpoint of each fourth line segment is selected as the initial evaluation point P0.

[0144] The remaining length of the reference edge is divided into multiple fourth segments. The midpoint of each fourth segment is selected as the initial evaluation point P0. This allows for the acquisition of uniform initial evaluation points P0, as well as initial evaluation points P0 located at the center of each fourth segment. The initial evaluation points P0 are in a uniform and unbiased position relative to the remaining length of the reference edge, ensuring that subsequent evaluation points are also in a uniform and unbiased position along the remaining length of the polyline edge, further making the correction of the polyline edge more accurate.

[0145] It should be noted that the length of the fourth line segment should not be too large or too small. If the length of the fourth line segment is too large, there will be too few fourth line segments, resulting in too few initial evaluation points P0 and consequently too few subsequent evaluation points. This makes it difficult to achieve overall convergence of the polygonal edge by performing edge placement error convergence processing at the evaluation points, thus affecting the result of the optical proximity correction processing. If the length of the fourth line segment is too small, there will be too many fourth line segments, resulting in too many initial evaluation points P0 and consequently too many subsequent evaluation points. This increases the number of unnecessary convergence points during edge placement error convergence processing at the evaluation points, making edge placement error convergence more difficult and increasing unnecessary correction processing time, thus affecting the progress of the optical proximity correction processing. Therefore, in this embodiment, the length of the fourth line segment is set to an appropriate value based on the size of the remaining reference edge length and on empirical evidence.

[0146] In this embodiment, it also includes: setting up multiple initial evaluation points P0 on other sides of the reference graphic.

[0147] In this embodiment, the difference between the reference graphic and the design graphic is very small. Therefore, the initial evaluation points P0 corresponding to the evaluation points required for each side of the design graphic can be set on the reference graphic and then mapped uniformly. This unifies the steps of setting evaluation points, making the optical proximity correction process less complicated and easier to operate. Furthermore, since the reference graphic is a rectangle or a square, the operation of setting the initial evaluation points P0 on the reference graphic is even simpler.

[0148] The evaluation point generation module 505 is used to map multiple initial evaluation points P0 onto the polyline edge along a direction perpendicular to the reference edge, forming evaluation points P located on the polyline edge.

[0149] Evaluation point P is used as the specific location of the difference between the simulated image and the target simulated image in the optical proximity correction process, thereby obtaining the edge placement error used to determine whether the optical proximity correction is completed.

[0150] In this embodiment, the method further includes: mapping multiple initial evaluation points P0 established on other sides of the reference graphic onto the design graphic in a direction perpendicular to the corresponding other sides, thereby forming evaluation points P located on the design graphic.

[0151] In this embodiment, by using the initial evaluation point P0 established by the reference graphic, the evaluation points of each side of the design graphic are obtained. This avoids the problem of uneven establishment of evaluation points P and the easy loss of evaluation points P near the step position, while improving the efficiency of establishing evaluation points P, thereby improving the efficiency of optical proximity correction processing.

[0152] The optical proximity correction module 506 is used to perform optical proximity correction processing on the design graphic until the edge placement error at the evaluation point P meets the preset conditions, thus forming the corrected graphic.

[0153] In this embodiment, model-based optical proximity correction (OPC) is used to correct the design pattern. During the correction process, an optical model and a photoresist photochemical reaction model are used to calculate the simulated pattern of the design pattern after exposure. The OPC compares the outline of the simulated pattern after exposure with the outline of the target simulated pattern; the difference between them is called edge placement error. Edge placement error is an indicator used to measure the quality of the correction; the smaller the edge placement error, the closer the exposed pattern is to the target pattern.

[0154] In other embodiments, optical proximity correction can be performed using empirical rule-based optical proximity correction, or a combination of model-based and empirical rule-based optical proximity correction. In still other embodiments, other suitable optical proximity correction methods can be selected.

[0155] In this embodiment, the edge position error at evaluation point P is calculated, and optical proximity correction is performed by converging the edge position error at evaluation point P.

[0156] In this embodiment, in the step of performing optical proximity correction processing on the design graphic until the edge placement error at evaluation point P meets the preset condition, the preset condition is that the absolute value of the edge placement error is less than or equal to a preset value. The preset value should not be too large or too small. If the preset value is too large, even when the absolute value of the edge placement error at evaluation point P is less than or equal to the preset value, the edge placement error is still large and has not converged, making it difficult to achieve the correction effect of optical proximity correction. If the preset value is too small, the correction accuracy of the optical proximity correction processing is increased to an unnecessarily high level, the requirement for edge placement error convergence is too stringent, increasing the computational load of the optical proximity correction processing and making the correction process difficult. Therefore, in this embodiment, the preset value is set appropriately based on experience.

[0157] In this embodiment, the position of the third line segment where the evaluation point P is located is adjusted.

[0158] To reduce the arbitrariness of edge movement, edge placement errors are reduced by adjusting the position of line segments (e.g., translating line segments). In this embodiment, optical proximity correction is performed by adjusting the position of the third line segment where the evaluation point P is located.

[0159] Specifically, one or more correction operations are performed until the edge placement error at the evaluation point P meets the preset conditions. The correction operations include: simulating exposure of the design graphic to obtain a simulated graphic.

[0160] The simulated graphic is used to compare with the target simulated graphic to obtain the edge placement error corresponding to the simulated graphic.

[0161] In this embodiment, the edge placement error between the simulated graphic and the ideal simulated graphic at the evaluation point P is calculated.

[0162] Correspondingly, at evaluation point P, if the edge placement error of the simulated graphic is greater than 0, it means that the simulated graphic is located outside the target simulated graphic; if the edge placement error of the simulated graphic is less than 0, it means that the simulated graphic is located inside the target simulated graphic; and if the edge placement error of the simulated graphic is equal to 0, it means that the simulated graphic is located on the target simulated graphic.

[0163] In other embodiments, a graphic with a certain bias based on the design graphic can be formed as an ideal graphic, thereby allowing the calculation of the edge placement error between the simulated graphic and the ideal graphic at the location of the evaluation point.

[0164] In this embodiment, the position of the third line segment where the evaluation point P is located is adjusted according to the edge placement error.

[0165] Specifically, along the direction perpendicular to the third line segment, when the edge placement error is greater than 0, the corresponding third line segment is moved into the design drawing; when the edge placement error is less than 0, the corresponding third line segment is moved out of the design drawing; when the edge placement error is equal to 0, the position of the corresponding third line segment is maintained, that is, the third line segment is not moved.

[0166] It should be noted that after each correction operation, the design graphic obtained by moving the third line segment in the previous correction operation is used as the design graphic for simulated exposure in the next iteration. In other words, the design graphic obtained after adjusting the position of the third line segment is used as the design graphic for simulated exposure in the next correction operation.

[0167] When the edge placement error of the evaluation point P meets the preset conditions, the design graphic after adjusting the position of the third line segment is used as the corrected graphic.

[0168] Accordingly, the present invention also provides a photomask, comprising: a pattern obtained using the optical proximity correction method provided in the embodiments of the present invention.

[0169] As can be seen from the foregoing embodiments, a straight reference edge is formed corresponding to the polygonal edge of the design graphic. When setting initial evaluation points, the straight reference edge is used as a reference. The initial evaluation points are set relatively evenly across the entire reference edge. Correspondingly, the evaluation points mapped onto the polygonal edge are also set relatively evenly across the entire polygonal edge. Compared to the scheme of directly setting evaluation points on the polygonal edge, the embodiments of the present invention help to avoid the problem that the correction model might mistakenly identify the first line segment as a different edge due to the step position of the polygonal edge, and set evaluation points separately for each first line segment. This helps to avoid uneven setting of evaluation points and the problem of uneven setting of evaluation points on the platform. This invention addresses the issue of missing evaluation points near step positions. Furthermore, it eliminates the time required for special processing near step positions to prevent uneven evaluation point placement and missing evaluation points, thus improving the efficiency of optical proximity correction. Moreover, the relatively uniform placement of evaluation points along the broken edge facilitates more precise correction of the broken edge by controlling edge placement errors at the evaluation points, thereby improving the accuracy of optical proximity correction. Correspondingly, the use of a mask to form a mask pattern on the wafer enhances the matching degree between the mask pattern formed on the wafer and the target pattern.

[0170] This invention also provides a device that can implement the optical proximity correction method provided in this invention by loading a program, as described above. An optional hardware structure of the terminal device provided in this invention can be as follows: Figure 12As shown, it includes: at least one processor 01, at least one communication interface 02, at least one memory 03, and at least one communication bus 04.

[0171] In this embodiment, the number of processor 01, communication interface 02, memory 03, and communication bus 04 is at least one, and the processor 01, communication interface 02, and memory 03 communicate with each other through communication bus 04. Communication interface 02 can be an interface of a communication module for network communication, such as the interface of a GSM module. Processor 01 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. Memory 03 may include high-speed RAM and may also include non-volatile memory (NVM), such as at least one disk storage device. Memory 03 stores one or more computer instructions, which are executed by processor 01 to implement the optical proximity correction method provided in this embodiment of the present invention.

[0172] It should be noted that the aforementioned terminal device may also include other devices (not shown) that may not be essential to understanding the content disclosed in the embodiments of the present invention; given that these other devices may not be essential for understanding the content disclosed in the embodiments of the present invention, the embodiments of the present invention will not describe them one by one.

[0173] This invention also provides a storage medium storing one or more computer instructions for implementing the optical proximity correction method provided in this invention.

[0174] In the optical proximity correction method provided by this invention, a straight reference edge is formed corresponding to the polygonal edge of the design pattern. When setting initial evaluation points, the straight reference edge is used as a reference. The initial evaluation points are set relatively evenly across the reference edge. Correspondingly, the evaluation points mapped onto the polygonal edge are also set relatively evenly across the polygonal edge. Compared with the scheme of setting evaluation points directly on the polygonal edge, this invention helps to avoid the problem that the correction model might mistakenly identify the first line segment as a different edge due to the step position of the polygonal edge, and set evaluation points for each first line segment separately. This helps to avoid the problems of uneven evaluation point setting and the easy loss of evaluation points near the step position. At the same time, this invention also saves the time of special processing near the step position to prevent uneven evaluation point setting and the loss of evaluation points near the step position, thus improving the efficiency of optical proximity correction processing. Moreover, setting evaluation points relatively evenly across the polygonal edge helps to control the edge placement error at the evaluation points, making the correction of the polygonal edge more accurate, thereby improving the accuracy of optical proximity correction.

[0175] The embodiments of the present invention described above are combinations of elements and features of the present invention. Unless otherwise stated, elements or features may be considered optional. Individual elements or features may be practiced without combination with other elements or features. Furthermore, embodiments of the present invention may be constructed by combining some elements and / or features. The order of operations described in the embodiments of the present invention may be rearranged. Some constructions of any embodiment may be included in another embodiment and may be replaced by corresponding constructions of another embodiment. It will be apparent to those skilled in the art that claims in the appended claims that are not expressly referenced in each other may be combined to form embodiments of the present invention, or may be included as new claims in amendments made after the filing of this application.

[0176] Embodiments of the present invention can be implemented by various means, such as hardware, firmware, software, or combinations thereof. In a hardware configuration, the method according to an exemplary embodiment of the present invention can be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc. In a firmware or software configuration, embodiments of the present invention can be implemented in the form of modules, processes, functions, etc. Software code can be stored in memory units and executed by a processor. The memory units are located inside or outside the processor and can send data to and receive data from the processor via various known means.

[0177] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

[0178] 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: Provide design graphics; Along the outline of the design graphic, an edge with steps is obtained as a polyline edge, which is alternately composed of multiple first line segments extending along the extension direction of the polyline edge and second line segments connecting adjacent first line segments. In the step of obtaining the edge with steps as the broken line edge along the outline of the design graphic, the ratio of the length of the second line segment to the length of the first line segment is less than or equal to 1:

3. The broken line edges of the design graphic are subjected to step elimination processing, and the broken line edges are replaced with straight reference edges that extend in the same direction as the first line segment, forming a reference graphic corresponding to the design graphic. Multiple initial evaluation points are established on the reference edge; Multiple initial evaluation points are mapped onto the polyline edge along a direction perpendicular to the reference edge to form evaluation points located on the polyline edge; The design graphic is subjected to optical proximity correction processing until the edge placement error at the evaluation point meets the preset conditions, thus forming the corrected graphic.

2. The optical proximity correction method as described in claim 1, characterized in that, The steps for eliminating steps on the broken line edges of the design graphic include: selecting any one of the first line segments as the positioning line segment in the broken line edges; The remaining first line segments in the broken line edge are all translated in a direction perpendicular to the first line segment to a position flush with the positioning line segment. The translated first line segments are connected with the positioning line segment to form the straight reference edge.

3. The optical proximity correction method as described in claim 2, characterized in that, In the step of selecting any one of the first line segments as the positioning line segment among the broken line edges, the first line segment located on the outermost side of the design graphic is selected as the positioning line segment.

4. The optical proximity correction method as described in claim 1, characterized in that, In the step of establishing multiple initial evaluation points on the reference edge, the spacing between adjacent initial evaluation points is equal.

5. The optical proximity correction method as described in claim 1, characterized in that, Before performing optical proximity correction processing on the design graphic, the method further includes: segmenting the edges of the design graphic to obtain a plurality of sequentially connected third line segments; The steps for performing optical proximity correction on the design graphic include: adjusting the position of the third line segment where the evaluation point is located.

6. The optical proximity correction method as described in claim 5, characterized in that, Before establishing multiple initial evaluation points on the reference edge, the method further includes: setting the design graphic based on experience to obtain an ideal simulation graphic; The steps of optical proximity correction processing for the design graphic include: performing one or more correction operations until the edge placement error at the evaluation point position meets the preset conditions. The correction operation includes: performing simulated exposure on the design graphic to obtain a simulated graphic. Calculate the edge placement error between the simulated graphic and the ideal simulated graphic at the location of the evaluation point; Based on the edge placement error, adjust the position of the third line segment where the evaluation point is located; Wherein, when the edge placement error of the evaluation point meets the preset conditions, the design graphic after adjusting the position of the third line segment is used as the corrected graphic.

7. The optical proximity correction method as described in claim 6, characterized in that, The step of setting the design graphic based on experience to obtain the ideal simulation graphic includes: rounding the corners of adjacent sides of the design graphic, wherein the lengths of the two ends of the broken line edge used for rounding are a first length and a second length, respectively; In the step of setting up multiple initial evaluation points on the reference edge, a first length and a second length are respectively cut off at both ends of the reference edge, and multiple initial evaluation points are set up on the remaining length of the reference edge.

8. The optical proximity correction method as described in claim 7, characterized in that, The step of establishing multiple initial evaluation points on the reference edge of the remaining length includes: dividing the reference edge of the remaining length into multiple fourth line segments; The midpoint of each of the fourth line segments is selected as the initial evaluation point.

9. The optical proximity correction method as described in claim 1, characterized in that, In the step of performing optical proximity correction processing on the design graphic until the edge placement error at the evaluation point meets the preset condition, the preset condition is: the absolute value of the edge placement error is less than or equal to the preset value.

10. The optical proximity correction method as described in claim 2, characterized in that, The step of setting up multiple initial evaluation points on the reference edge further includes setting up multiple initial evaluation points on other edges of the reference graphic; The step of mapping multiple initial evaluation points onto the polyline edge along a direction perpendicular to the reference edge to form evaluation points located on the polyline edge further includes: mapping multiple initial evaluation points established on other edges of the reference graphic onto the design graphic along a direction perpendicular to the corresponding other edges to form evaluation points located on the design graphic.

11. The optical proximity correction method as described in claim 1, characterized in that, In the step of eliminating steps on the broken edge of the design graphic, the shape of the reference graphic is a square or a rectangle.

12. The optical proximity correction method as described in claim 1, characterized in that, In the step of providing design drawings, the design drawings include interconnect plug drawings.

13. An optical proximity correction system, characterized in that, include: The graphics provider module is used to provide design graphics; The polyline edge acquisition module is used to acquire the edge with steps as a polyline edge along the outline of the design graphic. The polyline edge is composed of multiple first line segments extending along the extension direction of the polyline edge and second line segments connecting adjacent first line segments alternately. The ratio of the length of the second line segment to the length of the first line segment is less than or equal to 1:

3. The reference edge forming module is used to perform step elimination processing on the polyline edge of the design graphic, replace the polyline edge with a straight reference edge that extends in the same direction as the first line segment, and form a reference graphic corresponding to the design graphic. An initial evaluation point generation module is used to establish multiple initial evaluation points on the reference edge; The evaluation point generation module is used to map multiple initial evaluation points onto the polyline edge along a direction perpendicular to the reference edge, forming evaluation points located on the polyline edge; An optical proximity correction module is used to perform optical proximity correction processing on the design graphic until the edge placement error at the evaluation point meets the preset conditions, thus forming the corrected graphic.

14. A photomask, characterized in that, include: The image obtained using the optical proximity correction method as described in any one of claims 1-12.

15. A device, characterized in that, It includes at least one memory and at least one processor, the memory storing one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the optical proximity correction method as described in any one of claims 1-12.

16. A storage medium, characterized in that, The storage medium stores one or more computer instructions for implementing the optical proximity correction method as described in any one of claims 1-12.

Images