Optical proximity correction method and mask

Abstract

An optical proximity correction method and mask, the method comprising: providing an original layout pattern; obtaining an edge profile of the original layout pattern; dividing the edge profile of the original layout pattern into multiple segments; dividing the original layout pattern using a first window as a unit; creating a second window with the first window as the window inner area; the second window including the window outer area of ​​the first window, the first window and the second window being co-centered; performing accelerated iterative calculations on the edge placement errors of the segments in the inner and outer areas of the window based on information about how the edge placement errors of the segments are affected by the correction amounts of adjacent segments, correcting the original layout pattern, and obtaining a target layout pattern. Because the correction of the original layout pattern is based on information about how the edge placement errors of the segments are affected by the correction amounts of adjacent segments, i.e., taking into account the correlation effect between adjacent segments, the correction amount determined for each segment has a high degree of accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to an optical proximity correction method and a mask. Background Art

[0002] Photolithography is a crucial technology in semiconductor manufacturing. It can transfer patterns from the mask to the silicon wafer to form semiconductor products that meet the design requirements.

[0003] In semiconductor manufacturing, as design dimensions continue to shrink, the diffraction effect of light becomes increasingly pronounced, ultimately leading to optical image degradation of the designed pattern. The actual photolithographic pattern formed is severely distorted relative to the pattern on the mask, ultimately causing the actual pattern formed by photolithography on the silicon wafer to be different from the designed pattern. This phenomenon is called the Optical Proximity Effect (OPE).

[0004] In order to correct the optical proximity effect, Optical Proximity Correction (OPC) was created. The core idea of ​​optical proximity correction is to establish an optical proximity correction model based on the consideration of offsetting the optical proximity effect, and design the photomask pattern according to the optical proximity correction model. In this way, although the optical proximity effect will occur when the lithography pattern corresponds to the photomask pattern, since the offset of this phenomenon has been taken into account when designing the photomask pattern according to the optical proximity correction model, the lithography pattern after photolithography is close to the original layout pattern that the user actually wants to obtain.

[0005] In existing optical proximity correction methods, after providing the original layout pattern, the entire optical proximity correction process includes multiple cycles. Each cycle corrects the original layout pattern to obtain an adjusted initial sub-pattern and calculates the edge placement error (EPE). The completion of the correction is determined by judging whether the edge placement error meets the standard, and finally a corrected pattern that meets the standard is obtained. Summary of the Invention

[0006] The problem solved by the present invention is to provide an optical proximity correction method and a mask to improve the accuracy of optical proximity correction.

[0007] To solve the above problems, the present invention provides an optical proximity correction method, which includes:

[0008] Provide original layout graphics;

[0009] Obtaining the edge contour of the original layout graphic;

[0010] Segmenting the edge contour of the original layout graphic into multiple segments;

[0011] dividing the original layout graphic based on the first window;

[0012] Creating a second window with the first window as the window inner area; the second window includes the window outer area of ​​the first window, and the first window and the second window share a common center;

[0013] Based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, accelerated iterative calculation is performed on the edge placement error of the segment in the inner and outer areas of the window, the original layout pattern is corrected, and the target layout pattern is obtained.

[0014] Optionally, based on information about how the edge placement error of the segment is affected by the correction amount of the adjacent segment, performing accelerated iterative calculation on the edge placement error of the segment in the inner and outer areas of the window, correcting the original layout pattern, and obtaining the target layout pattern includes:

[0015] Providing a current layout graphic; initially, the current layout graphic is the original layout graphic;

[0016] Traversing the first window of the current layout graphic to obtain the current first window and the corresponding second window;

[0017] Based on information about the influence of the correction amount of each segment in the second window on the edge placement errors of all segments in the second window, obtaining information about the target correction amount corresponding to each segment in the current first window;

[0018] offsetting the segments in the current first window by corresponding target correction amounts;

[0019] When it is determined that the first window in the current layout pattern has not been traversed completely, obtaining the next first window as the current first window, and restarting the step of obtaining information of a target correction amount corresponding to each segment in the current first window based on information of an influence of a correction amount of each segment in the second window on edge placement errors of all segments in the second window, until the traversal of the multiple first windows is completed to obtain a corresponding corrected layout pattern;

[0020] When it is determined that the traversal of the first window in the current layout graph is completed, determining whether a preset first iteration stop condition is met;

[0021] When it is determined that the first iteration stop condition has not been met, taking the revised layout graphic as the current layout graphic, and restarting the step of traversing the first window of the current layout graphic to obtain the traversed current first window and the corresponding second window until the first iteration stop condition is met;

[0022] When it is determined that the first iteration stop condition is met, the revised layout pattern is used as the target layout pattern.

[0023] Optionally, the first iteration stopping condition includes the number of iterations reaching a first threshold.

[0024] Optionally, the first threshold is 2 to 5 times.

[0025] Optionally, the step of obtaining information of a target correction amount corresponding to each segment in the current first window includes:

[0026] Acquiring information on current correction amounts of segments within the second window; the segments within the second window include segments other than the segments within the previous first window;

[0027] Applying corresponding current correction amounts to each segment within the second window to obtain a corrected second window graphic;

[0028] Obtaining a simulated exposure pattern corresponding to the corrected second window pattern;

[0029] Comparing the corrected second window pattern with the simulated exposure pattern to obtain information on edge placement errors of segments within the second window;

[0030] constructing an edge position interference matrix for the segments within the second window based on information about the current correction amount and edge placement error of the segments within the second window;

[0031] Calculating information of a next correction amount for the segment within the second window based on the edge placement error information and the edge position interference matrix of the segment within the second window;

[0032] Determine whether the preset second iteration stop condition is reached;

[0033] When it is determined that the second iterative stopping condition has not been met, taking the next correction amount of the segment in the second window as the current correction amount of the segment in the second window, and restarting the step of applying the corresponding current correction amount to each segment in the second window to obtain a corrected second window graphic until the second iterative stopping condition is met;

[0034] When it is determined that the second iteration stop condition is met, information on the next correction amount of each segment in the current first window is obtained from the next correction amount of the segment in the second window as the target correction amount of each segment in the current first window.

[0035] Optionally, the position interference matrix includes:

[0036] a diagonal element representing an edge placement error generated by any of the segments in the second window when a corresponding correction amount is applied to any of the segments in the second window; and

[0037] The non-diagonal elements represent edge placement errors generated by applying a corresponding correction amount to any segment in the second window, except for the segment in the second window.

[0038] Optionally, the edge position interference matrix includes:

[0039]

[0040] Among them, T ij represents the element of the i-th row and j-th column of the edge position interference matrix, represents the current correction value Δf of the jth segment in the second window j The edge placement error ΔEpe for the i-th segment i The impact produced, n represents the number of segments in the second window.

[0041] Optionally, the step of calculating information of the next correction amount of the segment within the second window includes:

[0042] Calculating the inverse matrix of the edge position interference matrix;

[0043] Based on the inverse matrix and the edge placement error of the segment within the second window, information about the next correction amount of the segment within the second window is calculated.

[0044] Optionally, in the step of obtaining information on the target correction amount corresponding to each segment in the current first window, the inverse matrix of the edge position interference matrix is ​​kept unchanged during at least two consecutive iterations, and the edge placement error information of the segments in the second window is updated.

[0045] Optionally, the next correction amount for each segment in the second window is:

[0046]

[0047] Among them, ΔEpe j is the edge placement error of the jth segment in the second window, Δf i is the next correction value of the i-th segment in the second window.

[0048] Optionally, the second iteration stopping condition includes the number of iterations reaching a second threshold.

[0049] Optionally, the second threshold is 2 to 5 times.

[0050] Optionally, the first window is rectangular.

[0051] Optionally, the size of the first window is (1-3 μm)*(1-3 μm).

[0052] Optionally, the second window is rectangular.

[0053] Optionally, a size of the second window is (1-5 μm)*(1-5 μm).

[0054] Correspondingly, an embodiment of the present invention further provides a mask, wherein the mask includes a mask pattern manufactured using any one of the optical proximity correction methods described above.

[0055] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0056] The optical proximity correction method provided in an embodiment of the present invention includes: providing an original layout pattern; obtaining an edge contour of the original layout pattern; dividing the edge contour of the original layout pattern into multiple segments; dividing the original layout pattern using a first window as a unit; creating a second window with the first window as the window inner area; the second window including the window outer area of ​​the first window, the first window and the second window being concentric; based on information about how the edge placement error of the segment is affected by the correction amount of the adjacent segment, performing accelerated iterative calculation on the edge placement error of the segment in the inner and outer areas of the window, correcting the original layout pattern, and obtaining a target layout pattern. Since the original layout pattern is corrected based on the information about how the edge placement error of the segment is affected by the correction amount of the adjacent segment, that is, taking into account the correlation effect between adjacent segments, the edge placement error of the segment of the edge contour of the target layout pattern finally obtained meets the requirements and has good critical dimension uniformity, so that the correction amount determined for each segment has high accuracy.

[0057] Furthermore, in the step of obtaining information on the target correction amount corresponding to each segment in the current first window, the inverse matrix of the edge position interference matrix is ​​kept unchanged during at least two consecutive iterations, and the edge placement error information of the segments in the second window is updated, which can save calculation time and improve the efficiency of optical proximity correction.

[0058] Description of the attached figure

[0059] Figure 1 is a schematic flow chart of an optical proximity correction method according to an embodiment of the present invention;

[0060] Figure 2 A schematic diagram of an original layout graphic according to an embodiment of the present invention;

[0061] Figure 3 is a schematic diagram of a first window set in a current layout graphic according to an embodiment of the present invention;

[0062] Figure 4 A flowchart corresponding to the step of correcting the original layout pattern to obtain a target layout pattern based on information that the edge placement error of the segment obtained by segmentation is affected by the correction amount of the adjacent segment in an embodiment of the present invention;

[0063] Figure 5 is a schematic diagram of a first window and a corresponding second window set in a current layout graphic according to an embodiment of the present invention;

[0064] Figure 6 2 is a flow chart of obtaining a target correction value corresponding to each segment in the current first window according to an embodiment of the present invention;

[0065] Figure 7 Schematic diagram of the positional relationship between adjacent first windows and adjacent second windows in the current layout graph in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] As known from the background art, the existing optical proximity correction method has the problem of low precision.

[0067] The most widely used optical proximity correction method is the model-based optical proximity correction method. Its basic principle is to simulate the original layout pattern by establishing an exposure model based on specific lithography conditions to obtain the simulation error. Then, the original layout pattern is divided into multiple corresponding segments according to certain rules. The segments are offset compensated according to the simulation error and re-simulated. After several rounds of simulation and correction, the simulation results are consistent with the target layout. Figure 1 Corrected layout.

[0068] The essence of the optical proximity correction method is mask optimization (MO). Existing optical proximity correction methods include global mask optimization (MO) and local mask optimization (LMO).

[0069] The global mask optimization method obtains the segment correction amount by minimizing the cost function. Although it can make the edge contour of the corrected layout pattern have better critical dimension uniformity (CD Uniformity), it may cause the edge placement error of some segments to not meet the standard requirements.

[0070] The local mask optimization method obtains the segment correction amount by minimizing the absolute value of the edge placement error of each segment, but it may cause large fluctuations in the edge contour of the corrected layout pattern, resulting in poor uniformity of the critical dimension.

[0071] To solve the above problems, the optical proximity correction method in an embodiment of the present invention corrects the original layout graphic based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segments, that is, taking into account the correlation effect between adjacent segments, so that the edge placement errors of the segmented edge contours of the target layout graphic finally obtained meet the requirements and have good critical dimension uniformity, so that the target layout graphic finally obtained has higher accuracy.

[0072] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0073] Figure 1 A schematic flow chart of an optical proximity correction method in an embodiment of the present invention is shown.

[0074] See also Figure 1 , execute step S101 to provide an original layout graphic.

[0075] The original layout pattern is a pre-set pattern that needs to be generated in the mask, which can be determined according to different semiconductor process requirements.

[0076] The original layout is created using a rule-based retargeting method.

[0077] The original layout graphics are stored in an original layout file. The original layout file refers to a layout file containing design graphics designed using an EDA tool. Generally speaking, the original layout file is a layout file that has passed the Design Rule Check (DRC).

[0078] In this embodiment, the file format of the original layout graphics is GDS format. In other embodiments, the file format of the original layout graphics can also be other formats such as OASIS.

[0079] The original layout graph includes multiple initial sub-graphs. For example, see Figure 2 , the multiple initial sub-graphs 101 to 106 are respectively in the shape of long strips, and the multiple initial sub-graphs 101 to 106 are parallel to each other. In other embodiments, the initial sub-graphs can also be in other shapes, such as L-shaped, etc., and the present invention is not limited to this.

[0080] Continue to see Figure 1 , execute step S102 to obtain the edge contour of the original layout graphic.

[0081] Obtaining the edge contour of the original layout graphic, that is, obtaining the edge contours of multiple initial sub-graphics in the original layout graphic.

[0082] In this embodiment, the edge contour of the original layout pattern is obtained by analyzing the original layout pattern.

[0083] In this embodiment, the multiple initial sub-graphs in the original layout pattern are in the shape of strips, and the edge outlines of the multiple initial sub-graphs are correspondingly rectangular. In other embodiments, the outlines of the initial sub-graphs can also be complex polygons composed of multiple rectangles or squares, such as an L-shape.

[0084] Continue to see Figure 1 , execute step S103 to divide the edge contour of the original layout graphic into multiple segments.

[0085] The edge contour of the original layout pattern is divided into a plurality of segments, that is, the edge contour of the initial sub-pattern in the original layout pattern is divided into a plurality of segments.

[0086] In this embodiment, the length of each segment obtained by segmentation is 20 nm to 60 nm, and the length of each initial segment is different or at least partially different.

[0087] Continue to see Figure 1 , execute step S104 to divide the original layout graphic into units of the first window.

[0088] The original layout graphic is divided into units of first windows, that is, the multiple first windows divide the current layout graphic into corresponding multiple areas, so that the segments within the current layout graphic are subsequently corrected using the divided first windows as units.

[0089] The shape of the first window can be set according to actual needs. In this embodiment, the first window is rectangular. In other embodiments, the first window can also be polygonal, etc.

[0090] The size of the first window can be set according to actual needs. In this embodiment, the size of the first window is (1-3 μm)*(1-3 μm).

[0091] See also Figure 3 , which shows a schematic diagram of a first window set in the current layout graphic. The first window 30 includes multiple segments of one or more graphics to be corrected.

[0092] Continue to see Figure 1 , executing step S105, creating a second window with the first window as the window inner area; the second window includes the window outer area of ​​the first window, and the first window and the second window have the same center.

[0093] The corresponding second window is established based on the current first window. In this embodiment, the corresponding second window is established with the current first window as the center. In other words, the first window overlaps with the center of the corresponding second window, the first window occupies the inner area of ​​the second window, and the second window includes the first window and the outer area of ​​the first window. That is, the first window is used as the inner area of ​​the second window, and the part of the second window excluding the first window is used as the outer area.

[0094] Continue to see Figure 1 , execute step S106, based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, perform accelerated iterative calculation on the edge placement error of the segment in the inner and outer areas of the window, correct the original layout graphic, and obtain the target layout graphic.

[0095] The target layout pattern refers to the exposure pattern expected to be obtained in order to meet functional and production requirements.

[0096] Based on the information that the edge placement error of the segment obtained by segmentation is affected by the correction amount of the adjacent segment, one or more optical proximity corrections are performed on the original layout pattern to obtain the target layout pattern. For details, see Figure 4 .

[0097] See also Figure 4 The steps of performing accelerated iterative calculation on the edge placement errors of the segments in the inner and outer areas of the window based on information about how the edge placement errors of the segments are affected by correction amounts of adjacent segments, and correcting the original layout pattern to obtain the target layout pattern may specifically include:

[0098] Execute step S401 to provide a current layout graphic.

[0099] The current layout pattern is the original layout pattern or the revised layout pattern obtained in the previous iteration. Specifically, when executing the first iteration, the current layout pattern is the original layout pattern; when executing the second iteration to the Nth iteration (N is an integer greater than or equal to 2), the current layout pattern is the revised layout pattern obtained in the previous iteration.

[0100] Execute step S402 to traverse the first window of the current layout graphic to obtain the current first window and the corresponding second window.

[0101] In a specific implementation, the multiple first windows in the current layout graph may be traversed according to a preset scanning order.

[0102] In this embodiment, the multiple first windows in the current layout graphic are traversed in the order from left to right and from top to bottom. In other embodiments, the multiple first windows in the current layout graphic can also be traversed in the order from top to bottom, from left to right, or from the center to the surroundings, which is not limited here.

[0103] See Figure 5 , which shows a schematic diagram of a first window and a corresponding second window. The dashed box 40 represents the first window, and the dashed box 50 represents the second window corresponding to the first window 40. The first window 40 overlaps with the center of the corresponding second window 50, and the first window 40 occupies the central area of ​​the corresponding second window 50. This configuration ensures that the second window 50 includes not only segments that have a proximity effect with segments in the center area of ​​the first window 40, but also segments that have a proximity effect with segments in the edge area of ​​the first window 40.

[0104] The second window should not be too large or too small. When the second window is too large, it will include many segments that do not have a neighboring effect on the corresponding segments in the first window, which will not be helpful for the subsequent acquisition of the target correction amount in the current first window and will significantly increase the amount of calculation. When the second window is too small, the segments that have a neighboring effect on the segments located at the edge of the first window will be excluded, resulting in a lower accuracy of the target correction amount of the segments in the first window obtained later. Therefore, in this embodiment, the size of the second window is (1 to 5 μm) * (1 to 5 μm).

[0105] Execute step S403 to obtain information about a target correction amount corresponding to each segment in the current first window based on information about the impact of the correction amount of each segment in the second window on edge placement errors of all segments in the second window.

[0106] When obtaining information on the target correction amount corresponding to each segment in the first window, the current first window is expanded to a second window with the current first window as the center area. For the segments in the current first window, not only the neighbor correlation effect of the segments in the center area of ​​the first window is considered, but also the neighbor correlation effect of the segments at the edge of the first window is taken into account, so that the target correction amount corresponding to each segment in the current first window is more accurate.

[0107] In this embodiment, the step of obtaining the information of the target correction amount corresponding to each segment in the current first window includes an iterative process. For details, see Figure 6 .

[0108] Continue to see Figure 4 , execute step S404 to offset the segments in the current first window by the corresponding target correction amounts.

[0109] In a specific implementation, when obtaining the target correction amount corresponding to the segment in the current first window, the segment in the current first window is offset by the corresponding target correction amount according to the information of the target correction amount of each segment.

[0110] Specifically, when the target correction amount is positive, the corresponding segment is moved outward by a distance corresponding to the target correction amount; when the target correction amount is negative, the corresponding segment is moved outward by a distance corresponding to the absolute value of the target correction amount.

[0111] Execute step S405 to determine whether the traversal of the first window is completed; when the determination result is no, execute step S406; otherwise, execute step S407.

[0112] Execute step S406 to obtain the next first window as the current first window.

[0113] When it is determined that all first windows in the current layout graphic have not been traversed, the next first window is used as the current first window, and from step S403, based on the information of the impact of the correction amount of each segment in the second window on the edge placement error of all segments in the second window, the target correction amount corresponding to each segment in the current first window is obtained and the execution is restarted until the traversal of multiple first windows in the current layout graphic is completed and the corresponding corrected layout graphic is obtained.

[0114] Execute step S407 to determine whether the preset first iteration stop condition is met; when the determination result is no, execute step S408; otherwise, execute step S409.

[0115] In this embodiment, the first iteration stopping condition is that the number of iterations reaches a preset first threshold.

[0116] The first threshold value can be set according to actual process requirements. For example, the first threshold value can be set to 2 to 5 times.

[0117] Execute step S408 to use the corresponding revised layout graphic as the current layout graphic.

[0118] When it is determined that the first iteration stop condition has not been met, the revised layout graphic obtained in the current iteration is used as the current layout graphic, and from step S402, the first window of the current layout graphic is traversed, and the traversed current first window and the corresponding second window are obtained and the execution is restarted until the preset first iteration stop condition is met.

[0119] Execute step S409 to use the corresponding revised layout pattern as the target layout pattern.

[0120] When it is determined that the first iteration stop condition is met, the corresponding revised layout graphic obtained by executing the current iteration is output as the final target layout graphic.

[0121] Figure 6 A schematic diagram of a process for obtaining information on a target correction amount corresponding to each segment in the current first window based on information on the impact of the correction amount of each segment in the second window on the edge placement errors of all segments in the second window in an embodiment of the present invention is shown.

[0122] See Figure 6 A step of obtaining a target correction value corresponding to each segment in the current first window includes an iterative process, which may specifically include:

[0123] Execute step S601 to obtain information about the current correction amount of the segment within the second window.

[0124] Initially, that is, during the first sub-iteration, the current correction values ​​for each segment within the second window are all preset unit distance correction values. During the Mth iteration (M is an integer greater than or equal to 2), the current correction values ​​for each segment within the second window are the target correction values ​​obtained during the previous iteration. The unit distance correction values ​​can be set based on actual needs or prior experience and are not limited here.

[0125] In this embodiment, obtaining information about the current correction amount of a segment within the second window refers to obtaining information about the current correction amount of all segments in the second window pattern, excluding the segment within the previous first window. In other words, during one iteration of obtaining the corresponding correction layout pattern, if target correction amount information for a segment within the first window is obtained and the segments within the first window are offset by the corresponding target correction amount, the position of the segment within the first window will remain unchanged during subsequent iterations of obtaining target correction amount information for other segments within the first window.

[0126] For example, see Figure 7For adjacent first windows 701 and 702, corresponding second windows 701' and second windows 702' have overlapping portions, and second window 702' includes not only first window 702 but also first window 701. In an iterative process of obtaining the corresponding corrected layout pattern, after first obtaining the target correction amount for the segment within first window 701 and offsetting the segments within first window 701 by the corresponding target correction amount, in the subsequent iterative process of obtaining the target correction amount for the segment within first window 702, the position of the segment within first window 701 remains unchanged.

[0127] Step S602 is executed to apply corresponding current correction amounts to the segments in the second window respectively to obtain a corrected second window graphic.

[0128] When the current correction amount information of the segments in the second window is obtained, the segments in the second window are offset by the corresponding current correction amounts, thereby forming the corrected second window graphic.

[0129] In this embodiment, the corresponding current correction amount is applied to each segment in the second window, which corresponds to applying the corresponding current correction amount to each segment in the second window except the segment in the previous first window.

[0130] Execute step S603 to obtain a simulated exposure pattern corresponding to the corrected second window pattern.

[0131] The simulated exposure pattern is used to simulate a pattern formed on a wafer after the corrected second window pattern undergoes a photolithography process.

[0132] In this embodiment, the shape of the initial sub-pattern in the original layout pattern unit is a rectangle, and the shape of the corresponding pattern in the simulated exposure pattern is an ellipse.

[0133] Step S604 is executed to compare the corrected second window pattern with the simulated exposure pattern to obtain information on edge placement errors of the segments within the second window.

[0134] In this embodiment, the edge placement error of the segment within the second window graphic can be calculated using the following formula:

[0135] ΔEpe i =D i -W i (1)

[0136] Among them, ΔEpe i represents the edge placement error of the i-th segment in the second window, D i represents the position of the i-th segment in the second window, W irepresents the position of the i-th segment in the second window on the simulated exposure pattern.

[0137] Step S605 is executed to construct an edge position interference matrix of the segments in the second window based on the current correction amount and edge placement error information of the segments in the second window graphic.

[0138] In this embodiment, the edge position interference matrix of the segments in the second window includes information about the influence of the correction amount of each segment in the second window on the edge placement errors of all segments in the second window.

[0139] Specifically, in the position interference matrix, the diagonal elements represent the edge placement error generated by any segment in the second window when the corresponding correction amount is applied to the segment; the non-diagonal elements represent the edge placement error generated by all segments in the first window except any segment when the corresponding correction amount is applied to the segment in the second window.

[0140] It can be seen that the position interference matrix includes not only the impact of the edge placement error of any segment when the current correction amount is corrected, but also the impact on the edge placement errors of all other segments.

[0141] The position interference matrix takes into account the neighbor (correlation) effect between all segments in the segment neighborhood, and the correction amount of each segment determined thereby is a small movement with high precision, which is conducive to the correction of the original layout graphics and the subsequent OPC iteration process to converge quickly.

[0142] Specifically, the second window includes n segments, and the corresponding position interference matrix can be expressed as:

[0143]

[0144] Among them, T ij represents the element of the i-th row and j-th column of the edge position interference matrix, represents the current correction value Δf of the jth segment in the second window j The placement error ΔEpe of edge j of the i-th segment i The impact produced, n represents the number of segments in the second window graphics.

[0145] Step S606 is executed to calculate information on a next correction amount of the segment within the second window graphic based on the edge placement error information of the segment within the second window and the edge position interference matrix.

[0146] By applying the corresponding current correction amount to the segments within the second window and obtaining the edge placement error information and edge position interference matrix of the segments within the second window, the next correction amount information of the segments within the second window graphic can be calculated based on the edge placement error information and edge position interference matrix of the segments within the second window.

[0147] Specifically, the obtained edge placement error information of the segment in the second window, the edge position interference matrix, and the next correction amount of the segment in the second window graph satisfy the following relationship:

[0148]

[0149] According to the above formula (3), the step of calculating the next correction amount of the segment within the second window includes: calculating the inverse matrix of the edge position interference matrix; and calculating the information of the next correction amount of the segment within the second window based on the inverse matrix and the edge placement error of the segment within the second window.

[0150] Specifically, the next correction amount of the segment within the second window can be calculated using the following formula:

[0151]

[0152] Among them, ΔEpe j is the edge placement error of the jth segment in the second window, Δf i is the next correction value of the i-th segment in the second window.

[0153] Execute step S607 to determine whether the preset second iteration stop condition is met; when the determination result is no, execute step S608; otherwise, execute step S609.

[0154] In this embodiment, the second iteration stopping condition includes the number of iterations reaching a second threshold, wherein the second threshold is 2 to 5 times.

[0155] Step S608 is executed to use the next correction amount of the segment in the second window graph as the current correction amount of the segment in the second window graph.

[0156] When it is determined that the preset second iteration stop condition is not met, the next correction amount of the segment in the second window graphic is used as the current correction amount of the segment in the second window graphic, and the process is restarted from step S601 until the second iteration stop condition is met.

[0157] Execute step S609 to obtain information on the next correction amount of each segment in the current first window from the next correction amount of the segment in the second window graph as the target correction amount of each segment in the current first window.

[0158] When it is determined that the second iteration stop condition is met, information on the next correction amount of each segment in the current first window is obtained from the next correction amount of the segment in the second window as the target correction amount of each segment in the current first window.

[0159] In this embodiment, in the above-mentioned step of obtaining the information of the target correction amount corresponding to each segment in the current first window, the inverse matrix of the edge position interference matrix is ​​kept unchanged during at least two consecutive iterations, and the edge placement error information of the segment in the second window is updated to save calculation amount and speed up the calculation speed.

[0160] From the description of steps S601 to S609 above, it can be seen that when calculating the target correction amount of each segment in each first window, the first window is expanded into a corresponding second window, so that the second window not only includes segments with neighbor correlation effects with segments in the central area of ​​the first window, but also includes segments with neighbor correlation effects with segments in the edge area of ​​the first window, which can improve the accuracy of the target correction amounts of all segments obtained in the first window.

[0161] Accordingly, an embodiment of the present invention further provides a mask, the mask including a mask pattern produced by the optical proximity correction method. The optical proximity correction method is described in the above section and will not be described in detail.

[0162] The mask is used as a mask to expose the photoresist on the wafer to form a photoresist pattern for each chip area on the wafer. The chip area of ​​the wafer can be etched with the photoresist pattern to form semiconductor structures such as gates, metal interconnects or conductive plugs in the chip area of ​​the wafer.

[0163] It can be seen from the aforementioned embodiments that the target layout graphics obtained by the aforementioned embodiments are used to correct the original layout graphics based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segments, that is, taking into account the correlation effect between adjacent segments, so that the edge placement errors of the segmented edge contours of the target layout graphics finally obtained meet the requirements and have good critical dimension uniformity, so that the correction amount of each segment determined has high accuracy, thereby correspondingly improving the accuracy of the graphic transfer.

[0164] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. An optical proximity correction method, characterized in that: include: Provide original layout graphics; Obtaining the edge contour of the original layout graphic; Segmenting the edge contour of the original layout graphic into multiple segments; dividing the original layout graphic based on the first window; Creating a second window with the first window as the window inner area; the second window also includes the window outer area of ​​the first window, and the first window and the second window share a common center; Based on the information that the edge placement error of each segment in the corresponding second window is affected by the correction amount of the adjacent segment, accelerated iterative calculation is performed on the edge placement error of the segment in each first window, the original layout pattern is corrected, and the target layout pattern is obtained.

2. The optical proximity correction method according to claim 1, wherein: The steps of performing accelerated iterative calculation on the edge placement errors of the segments in each first window based on information that the edge placement error of each segment in the corresponding second window is affected by the correction amount of the adjacent segment, correcting the original layout pattern, and obtaining the target layout pattern include: Providing a current layout graphic; initially, the current layout graphic is the original layout graphic; Traversing the first window of the current layout graphic to obtain the current first window and the corresponding second window; Based on information about the influence of the correction amount of each segment in the second window on the edge placement errors of all segments in the second window, obtaining information about the target correction amount corresponding to each segment in the current first window; offsetting the segments in the current first window by corresponding target correction amounts; When it is determined that the first window in the current layout pattern has not been traversed completely, obtaining the next first window as the current first window, and restarting the step of obtaining information of a target correction amount corresponding to each segment in the current first window based on information of an influence of a correction amount of each segment in the second window on edge placement errors of all segments in the second window, until the traversal of the multiple first windows is completed to obtain a corresponding corrected layout pattern; When it is determined that the traversal of the first window in the current layout graph is completed, determining whether a preset first iteration stop condition is met; When it is determined that the first iteration stop condition has not been met, taking the revised layout graphic as the current layout graphic, and restarting the step of traversing the first window of the current layout graphic to obtain the traversed current first window and the corresponding second window until the first iteration stop condition is met; When it is determined that the first iteration stop condition is met, the revised layout pattern is used as the target layout pattern.

3. The optical proximity correction method according to claim 2, wherein: The first iteration stopping condition includes the number of iterations reaching a first threshold.

4. The optical proximity correction method according to claim 3, wherein: The first threshold is 2 to 5 times.

5. The optical proximity correction method according to claim 2, wherein: The step of obtaining information of the target correction amount corresponding to each segment in the current first window includes: Acquiring information on current correction amounts of segments within the second window; the segments within the second window include segments other than the segments within the previous first window; Applying corresponding current correction amounts to each segment within the second window to obtain a corrected second window graphic; Obtaining a simulated exposure pattern corresponding to the corrected second window pattern; Comparing the corrected second window pattern with the simulated exposure pattern to obtain information on edge placement errors of segments within the second window; constructing an edge position interference matrix for the segments within the second window based on information about the current correction amount and edge placement error of the segments within the second window; Calculating information of a next correction amount for the segment within the second window based on the edge placement error information and the edge position interference matrix of the segment within the second window; Determine whether the preset second iteration stop condition is reached; When it is determined that the second iterative stopping condition has not been met, taking the next correction amount of the segment in the second window as the current correction amount of the segment in the second window, and restarting the step of applying the corresponding current correction amount to each segment in the second window to obtain a corrected second window graphic until the second iterative stopping condition is met; When it is determined that the second iteration stop condition is met, information on the next correction amount of each segment in the current first window is obtained from the next correction amount of the segment in the second window as the target correction amount of each segment in the current first window.

6. The optical proximity correction method according to claim 5, wherein: The position interference matrix includes: A diagonal element represents an edge placement error generated by any edge when a corresponding correction amount is applied to any of the segments within the second window; and The non-diagonal elements represent edge placement errors generated by applying a corresponding correction amount to any segment in the second window, except for the segment in the second window.

7. The optical proximity correction method according to claim 5, wherein: The edge position interference matrix includes: Among them, T ij represents the element of the i-th row and j-th column of the edge position interference matrix, represents the current correction value Δf of the jth segment in the second window j The edge placement error ΔEpe for the i-th segment i The impact produced, n represents the number of segments in the second window.

8. The optical proximity correction method according to claim 7, wherein: The step of calculating information of the next correction amount of the segment within the second window includes: Calculating the inverse matrix of the edge position interference matrix; Based on the inverse matrix and the edge placement error of the segment within the second window, information about the next correction amount of the segment within the second window is calculated.

9. The optical proximity correction method according to claim 8, wherein: In the step of obtaining information on the target correction amount corresponding to each segment in the current first window, the inverse matrix of the edge position interference matrix is ​​kept unchanged during at least two consecutive iterations, and the edge placement error information of the segments in the second window is updated.

10. The optical proximity correction method according to claim 8, wherein: The next correction amount for each segment in the second window is: Among them, ΔEpe j is the edge placement error of the jth segment in the second window, Δf i is the next correction value of the i-th segment in the second window.

11. The optical proximity correction method according to claim 5, wherein: The second iteration stopping condition includes the number of iterations reaching a second threshold.

12. The optical proximity correction method according to claim 11, wherein: The second threshold is 2 to 5 times.

13. The optical proximity correction method according to claim 2, wherein: The first window is rectangular.

14. The optical proximity correction method according to claim 13, wherein: The size of the first window is (1-3 μm)*(1-3 μm).

15. The optical proximity correction method according to claim 2, wherein: The second window is rectangular.

16. The optical proximity correction method according to claim 15, wherein: The size of the second window is (1-5 μm)*(1-5 μm).

17. A mask, characterized in that: The invention comprises a mask pattern produced by the optical proximity correction method according to any one of claims 1 to 16.

Images