CN118550150A - Optical proximity correction method - Google Patents
Optical proximity correction method Download PDFInfo
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- CN118550150A CN118550150A CN202310167917.XA CN202310167917A CN118550150A CN 118550150 A CN118550150 A CN 118550150A CN 202310167917 A CN202310167917 A CN 202310167917A CN 118550150 A CN118550150 A CN 118550150A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/36—Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/38—Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
- G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
- G03F7/70441—Optical proximity correction [OPC]
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Abstract
An optical proximity correction method, comprising: obtaining a layout to be corrected from a plurality of split layouts; acquiring a sparse graph in the layout to be corrected, wherein the graph density of the sparse graph is lower than a preset density; acquiring reference position information of split graphics in a plurality of split layouts except the layout to be corrected; setting an initial auxiliary graph in the layout to be corrected according to the reference position information, wherein the initial auxiliary graph is positioned around the sparse graph, and the size of the initial auxiliary graph is smaller than or equal to the size of the split graph at the corresponding reference position; and carrying out correction processing on the initial auxiliary graph for a plurality of times to obtain the auxiliary graph, wherein the auxiliary graph and the split graph in the to-be-corrected graph form a corrected graph, and the simulated exposure graph of the corrected graph is provided with an exposure graph corresponding to the auxiliary graph, so that non-uniformity of etching deviation caused by non-uniformity of graph density is reduced, and uniformity of graph density of the whole graph is improved.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to an optical proximity correction method.
Background
As critical dimensions of semiconductor devices continue to shrink, pattern density is becoming far above the limit that can be handled by a single exposure. For this reason, multiple lithography techniques, such as Double Exposure (DE) process, multiple (or double) lithography techniques, etc., have been developed on the basis of the general photoresist-exposure-development-etching process. In multiple lithography, the "le+cut" process uses lithography (litho, abbreviated L) and etching (etching, abbreviated E) to form one-dimensional lines, which are then cut (cut) to achieve the desired pattern. In the fabrication of middle metal contact (MOL contact), metal contact with complex patterns can be made using a simple photomask using a "le+cut" process.
The core of the multiple photoetching technology is to split the original pattern of one layer of photoetching onto two or more masks, and realize the original pattern of one layer of design by multiple photoetching and etching, and the multiple photoetching technology is beneficial to obtaining higher pattern density and realizing smaller process nodes. However, when photolithography and etching are performed using each split mask, the process risk is still present due to the etching deviation caused by the pattern density.
The specific reasons are as follows:
The etch bias (etch bias) is the difference between the line width of the pattern on the substrate after etching and the line width of the pattern on the photoresist. In order to obtain the pattern of the design layout on the wafer, before performing optical proximity correction (optical proximity correction, abbreviated as OPC) of photolithography, etching correction is also required to be performed on the design layout. The pattern density is an important factor affecting the etching deviation, and a pattern (DENSE PATTERN) which is densely distributed and a pattern (iso pattern) which is sparse are usually arranged in a layout, so that a loading effect (loading effect) exists between the pattern density and the etching rate, the etching deviation of the region with lower pattern density is smaller, and the etching deviation of the region with higher pattern density is larger.
As the line width and pitch (pitch) become smaller, the effect of the loading effect becomes more pronounced and the effect on process stability becomes greater. For etching a region with lower pattern density, under an extreme condition, even if etching deviation value is too small, the size of a theoretical photoresist developing detection (after development inspection, abbreviated as ADI) obtained through optical proximity correction is smaller than the minimum critical size (critical dimension, abbreviated as CD) of a photoetching process, at the moment, a sparse pattern is always selected to be large, basic process requirements are preferentially met, but the excessive pattern is likely to have higher process risk, bridging (bridge) between patterns is extremely easy to generate, and abnormal occurrence of electric leakage and the like is caused. The existing optical proximity correction method is based on correction of the layout after etching correction, and the difference problem of etching deviation cannot be thoroughly solved.
In summary, although the existing multiple lithography techniques are beneficial to obtain higher pattern density and smaller process nodes, the problem of uneven etching deviation caused by pattern density cannot be avoided, and the existing optical proximity correction method needs to be further improved.
Disclosure of Invention
The invention solves the technical problem of providing an optical proximity correction method to reduce the problem of uneven etching deviation caused by pattern density difference.
In order to solve the above problems, the technical solution of the present invention provides an optical proximity correction method, including: providing a cutting layout, wherein the cutting layout comprises a plurality of cutting patterns; splitting the cutting layout into a plurality of splitting layouts, wherein each splitting layout is provided with a plurality of splitting graphs, and the splitting graphs in the splitting layouts are used for being combined into the cutting graphs; obtaining a layout to be corrected from a plurality of split layouts; acquiring a sparse graph in the layout to be corrected, wherein the graph density of the sparse graph is lower than a preset density; acquiring reference position information of split graphics in a plurality of split layouts except the layout to be corrected; setting an initial auxiliary graph in the layout to be corrected according to the reference position information, wherein the initial auxiliary graph is positioned around the sparse graph, and the size of the initial auxiliary graph is smaller than or equal to the size of the split graph at the corresponding reference position; and carrying out correction processing on the initial auxiliary graph for a plurality of times to obtain an auxiliary graph, wherein the auxiliary graph and the split graph in the to-be-corrected graph form a correction layout, and the simulated exposure graph of the correction layout is provided with an exposure graph corresponding to the auxiliary graph.
Optionally, the several correction processing methods include: forming a first transition layout by the initial auxiliary graph and the split graph in the layout to be corrected; performing conflict checking on the first transition layout, taking the initial auxiliary graph as an intermediate auxiliary graph when the first transition layout has no conflict, and performing first deformation correction on the initial auxiliary graph to obtain the intermediate auxiliary graph when the first transition layout has the conflict; after the conflict check, replacing the initial auxiliary graph with the intermediate auxiliary graph to form a second transition layout; performing simulated exposure on the second transition layout to obtain a simulated exposure pattern; when the simulated exposure pattern is provided with an exposure pattern corresponding to the intermediate auxiliary pattern, the intermediate auxiliary pattern is taken as the auxiliary pattern; when the simulation exposure pattern does not have the exposure pattern corresponding to the intermediate auxiliary pattern, performing second deformation correction on the intermediate auxiliary pattern to obtain a transition auxiliary pattern; after the transition auxiliary graph is obtained, replacing the initial auxiliary graph with the transition auxiliary graph to form an updated first transition layout; and performing conflict check again on the updated first transition layout to obtain an updated intermediate auxiliary graph and an updated second transition layout until an exposure graph corresponding to the intermediate auxiliary graph is arranged in the simulated exposure graph of the second transition layout, and taking the intermediate auxiliary graph as the auxiliary graph.
Optionally, the first deformation correction method for the initial auxiliary graph includes: one or more of clearing the initial assist feature that violates the reticle rule, clearing the initial assist feature that violates the etch rule, changing the size of the initial assist feature, and changing the shape of the initial assist feature.
Optionally, the initial auxiliary pattern that violates the reticle rule includes: the size of the initial auxiliary pattern is smaller than one or more of a preset line width, the distance between the adjacent initial auxiliary patterns is smaller than a preset distance, the distance between the initial auxiliary pattern and the split pattern is smaller than the preset distance, and the pattern area of the initial auxiliary pattern is smaller than the preset area.
Optionally, the initial auxiliary pattern violating the etching rule includes: the size of the initial assist feature is less than the photolithographic process limit.
Optionally, the sparse patterns include a first type sparse pattern and a second type sparse pattern, and the pattern density of the first type sparse pattern is lower than the pattern density of the second type sparse pattern; the initial auxiliary graph comprises a first initial auxiliary graph and a second initial auxiliary graph, the first initial auxiliary graph is positioned around the corresponding sparse graph, and the second initial auxiliary graph is positioned around the first initial auxiliary graph and the corresponding sparse graph; the auxiliary graphics comprise a first auxiliary graphics and a second auxiliary graphics, wherein the first auxiliary graphics are positioned around the corresponding sparse graphics, and the second auxiliary graphics are positioned around the first auxiliary graphics and the corresponding sparse graphics.
Optionally, the method for acquiring the sparse graph includes: dividing the split pattern into a first type sparse pattern and a second type sparse pattern according to the distance between the split pattern in the layout to be corrected and the split pattern around the split pattern.
Optionally, before setting the initial auxiliary graph and after acquiring the sparse graph, the method further includes: and taking any sparse graph as a center, acquiring a first correction area and a second correction area, wherein the first correction area has a first radius, the second correction area has a second radius, and the first radius is smaller than the second radius.
Optionally, the method comprises the following steps: the initial first auxiliary graph is positioned in the first correction area or intersected with the edge of the first correction area; the initial second auxiliary pattern is located outside the first correction region and is located within or intersects the second correction region edge.
Optionally, the first radius has a size in the range of 1.0 microns to 2.5 microns; the second radius has a size in the range of 2.5 microns to 5 microns.
Optionally, the method for setting the initial auxiliary graph and the method for acquiring the auxiliary graph further comprise: taking any first type sparse graph as a center to acquire the first correction area and the second correction area; setting the initial first auxiliary graph around the first sparse graph; performing correction processing on the initial first auxiliary graph around the first type sparse graph for a plurality of times to obtain the first auxiliary graph around the first type sparse graph; after the first auxiliary graph is acquired around the first type sparse graph, setting the initial second auxiliary graph around the first type sparse graph; performing correction processing on the initial second auxiliary graph around the first type sparse graph for a plurality of times to obtain the second auxiliary graph around the first type sparse graph; after the auxiliary graphics are arranged around all the first type sparse graphics, taking any second type sparse graphics as a center to obtain the first correction area and the second correction area; setting the initial first auxiliary graph around the second type sparse graph; performing correction processing on the initial first auxiliary graph around the second type sparse graph for a plurality of times to obtain the first auxiliary graph around the second type sparse graph; after the first auxiliary graph is arranged around the second type sparse graph, the initial second auxiliary graph is arranged around the second type sparse graph; and carrying out correction processing on the initial second auxiliary graph around the second type sparse graph for a plurality of times to obtain the second auxiliary graph around the second type sparse graph.
Optionally, the method for dividing the split graphics into the first type sparse graphics and the second type sparse graphics includes: obtaining splitting graphs to be judged from a plurality of splitting graphs of the layout to be corrected; taking the splitting graph to be determined as a center, respectively acquiring a first determination area and a second determination area in the layout to be corrected, wherein the edge of the first determination area is a third size from the center of the splitting graph to be determined, the edge of the second determination area is a fourth size from the center of the splitting graph to be determined, and the third size is larger than the fourth size; if no split pattern is positioned in the first judging area and the no split pattern is intersected with the edge of the first judging area in the layout to be corrected, the split pattern to be judged is a first type sparse pattern; if a split pattern in the layout to be corrected is intersected with the edge of the first judging area or the split pattern is positioned in the first judging area and outside the second judging area, the split pattern to be judged is a second type sparse pattern; if the split pattern in the layout to be corrected is located in the second judging area or intersects with the edge of the second judging area, the split pattern to be judged is a dense pattern.
Optionally, the third dimension ranges from 2.5 microns to 5 microns; the fourth dimension ranges from 1.0 microns to 2.5 microns.
Optionally, after obtaining the corrected layout, the method further includes: etching correction is carried out on the correction layout, and an etching correction layout is obtained; and performing optical proximity correction on the etching correction layout to obtain an optical correction layout.
Optionally, the method further comprises: providing a photoetching layout, wherein the photoetching layout comprises a plurality of photoetching patterns, and when the photoetching layout and the cutting layout are laminated, overlapping areas are formed between the plurality of cutting patterns and the plurality of photoetching patterns.
Compared with the prior art, the technical scheme of the invention has the following advantages:
In the optical proximity correction method of the technical scheme, the cutting layout is split into a plurality of split layouts, reference position information of split graphics in a plurality of split layouts except the layout to be corrected is obtained, an initial auxiliary graphic is arranged in the layout to be corrected according to the reference position information, the initial auxiliary graphic is positioned around the sparse graphic, correction processing is carried out on the initial auxiliary graphic for a plurality of times to obtain an auxiliary graphic, the auxiliary graphic has a corresponding exposure graphic, the graphic density around the sparse graphic can be improved, the non-uniformity of etching deviation caused by the non-uniformity of the graphic density is further reduced, and the uniformity of the graphic density of the whole layout is improved; in addition, as the auxiliary graph is set according to the reference position information of the split graph in a plurality of split graphs except the to-be-corrected graph, the multiple overlapping exposure of the split graph does not influence the appearance of the final exposure graph due to the specificity of the split graph of a CUT layer (trimming layer) in the LE+CUT process, so that the added auxiliary graph can not influence the appearance of the exposure graph after being exposed while improving the uniformity of the graph density of the whole graph; secondly, the auxiliary graph is inserted around the sparse graph, so that the method has higher freedom degree compared with the dummy graph (dummy pattern) inserted around the sparse graph, and is more suitable for being used in the actual chip of the advanced node complex environment.
Further, the sparse patterns comprise a first type sparse pattern and a second type sparse pattern, the pattern density of the first type sparse pattern is lower than that of the second type sparse pattern, and correction can be carried out according to the severity of influence of the sparse patterns on etching deviation, so that correction efficiency and accuracy are improved.
Further, before the initial auxiliary graph is set, and after the sparse graph is acquired, a first correction area and a second correction area are acquired by taking any sparse graph as a center, the first correction area has a first radius, the second correction area has a second radius, the first radius is smaller than the second radius, the first correction area and the second correction area are used for limiting the position of the auxiliary graph, and the first correction area and the second correction area with different sizes can be selected, so that correction efficiency and accuracy are improved.
Drawings
FIG. 1 is a schematic diagram of a layout structure of an optical proximity correction method;
FIGS. 2 to 5 are flowcharts illustrating an optical proximity correction method according to an embodiment of the present invention;
fig. 6 to 12 are schematic layout structures of each step of the optical proximity correction method according to the embodiment of the present invention.
Detailed Description
As described in the background art, the existing optical proximity correction method needs to be further improved. The following will specifically explain.
In order to solve the problem of uneven etching deviation caused by pattern density, in an optical proximity correction method, the uniformity of pattern density is improved by adding dummy patterns (dummy patterns) on a layout, so as to reduce the problem of loading effect of the process, refer to fig. 1.
FIG. 1 is a schematic diagram of a layout structure of an optical proximity correction method.
Referring to fig. 1, in the layout structure, the layout structure includes: a main pattern 101; a number of dummy patterns 102 located around the main pattern 101.
In the layout structure, the main pattern 101 is a sparse pattern, and a plurality of dummy patterns 102 are added around the main pattern 101, so that pattern density in the layout can be balanced in an auxiliary manner, and excessive sparse pattern generation is avoided. However, the setting of the dummy pattern 102 needs to follow the setting rule of the dummy pattern, and in the actual chip, such as a logic device area, a complex pattern area, etc., the redundant area around the sparse pattern is smaller or the sparse pattern is irregular, so that the generation of the sparse pattern cannot be reduced by adding the dummy pattern in batches, and further, the problem that the sparse pattern is too small due to etching deviation and possibly even lower than the etching process limit cannot be solved.
In order to solve the problems, the invention provides an optical proximity correction method, wherein the cutting layout is split into a plurality of split layouts, reference position information of split graphics in a plurality of split layouts except the layout to be corrected is obtained, an initial auxiliary graphic is arranged in the layout to be corrected according to the reference position information, the initial auxiliary graphic is positioned around the sparse graphic, the initial auxiliary graphic is subjected to correction processing for a plurality of times to obtain an auxiliary graphic, the auxiliary graphic is provided with a corresponding exposure graphic, the graphic density around the sparse graphic can be improved, the non-uniformity of etching deviation caused by non-uniformity of the graphic density is further reduced, and the uniformity of the graphic density of the whole layout is improved; in addition, as the auxiliary graph is set according to the reference position information of the split graph in a plurality of split graphs except the to-be-corrected graph, the multiple overlapping exposure of the split graph does not influence the appearance of the final exposure graph due to the specificity of the split graph of a CUT layer (trimming layer) in the LE+CUT process, so that the added auxiliary graph can not influence the appearance of the exposure graph after being exposed while improving the uniformity of the graph density of the whole graph; and secondly, compared with the insertion of dummy patterns around the sparse patterns, the insertion of auxiliary patterns around the sparse patterns has higher degree of freedom, and is more suitable for the internal use of an actual chip in an advanced node complex environment.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Fig. 2 to 5 are flowcharts of an optical proximity correction method according to an embodiment of the present invention.
Referring to fig. 2, the optical proximity correction method includes the following steps:
Step S201, providing a cutting layout, wherein the cutting layout comprises a plurality of cutting figures;
Step S202, splitting the cutting layout into a plurality of split layouts, wherein each split layout is provided with a plurality of split graphics, and the split graphics in the split layouts are used for being combined into the cutting graphics;
Step S203, obtaining a layout to be corrected from a plurality of split layouts;
Step S204, acquiring sparse graphs in the layout to be corrected, wherein the graph density of the sparse graphs is lower than a preset density;
Step S205, obtaining reference position information of split graphics in a plurality of split layouts except the layout to be corrected;
Step S206, setting an initial auxiliary graph in the layout to be corrected according to the reference position information, wherein the initial auxiliary graph is positioned around the sparse graph, and the size of the initial auxiliary graph is smaller than or equal to the size of the split graph at the corresponding reference position;
Step S207, carrying out correction processing on the initial auxiliary graph for a plurality of times to obtain an auxiliary graph, wherein the auxiliary graph and the split graph in the to-be-corrected graph form a corrected layout, and the simulated exposure graph of the corrected layout is provided with an exposure graph corresponding to the auxiliary graph.
The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.
Fig. 6 to 12 are schematic layout structures of each step of the optical proximity correction method according to the embodiment of the present invention.
With continued reference to fig. 2 and with reference to fig. 6, a cut layout 30 is provided, the cut layout 30 including a number of cut patterns 301.
In this embodiment, a lithographic layout 40 is further provided, where the lithographic layout 40 includes a plurality of lithographic patterns 401, and when the lithographic layout 40 and the dicing layout 30 are stacked, there is an overlapping area between the plurality of dicing patterns 301 and the plurality of lithographic patterns 401.
Specifically, the photolithography pattern 401 is parallel to a first direction, the cutting pattern 301 is parallel to a second direction, and the first direction and the second direction are perpendicular to each other. After obtaining a preliminary exposure pattern using the lithographic layout 40, exposure is performed using the cut layout 30 to further trim (cut) the exposure pattern to obtain a final target exposure pattern.
With continued reference to fig. 2, and with reference to fig. 7 to 8, the cutting layout 30 (shown in fig. 6) is split into a plurality of split layouts, each split layout has a plurality of split graphics, and the split graphics in the split layouts are used to be combined into the cutting graphics 301 (shown in fig. 6).
In this embodiment, the dicing layout 30 is split into a first split layout 51 and a second split layout 52, i.e. the number of split layouts is two. In other embodiments, the cutting layout may be split into more than two split layouts according to actual needs.
Specifically, the first split layout 51 includes a plurality of first split patterns 511, and the second split layout 52 includes a plurality of second split patterns 521; the number of split graphics includes the number of first split graphics 511 and the number of second split graphics 521.
With continued reference to fig. 2 and 8, the layout to be modified is obtained from a plurality of split layouts.
The first split layout 51 will be described later as a version to be corrected.
With continued reference to fig. 2, and with reference to fig. 9, a sparse pattern is obtained in the layout to be corrected, where the pattern density of the sparse pattern is lower than a preset density.
Specifically, a sparse pattern is obtained in the first split layout 51.
In this embodiment, the sparse patterns include a first type sparse pattern and a second type sparse pattern, and the pattern density of the first type sparse pattern is lower than the pattern density of the second type sparse pattern.
In this embodiment, the method for acquiring the sparse graph includes: dividing the split pattern into a first type sparse pattern and a second type sparse pattern according to the distance between the split pattern in the layout to be corrected and the split pattern around the split pattern.
The purpose of dividing the sparse graph into a first type sparse graph and a second type sparse graph is that: the subsequent correction can be carried out according to the severity of the influence of the sparse graph on the etching deviation, so that the correction efficiency and accuracy are improved. In other embodiments, the sparse graph may not be classified, or may be classified into more classes according to the degree of sparseness of the graph density distribution of the split graph.
In this embodiment, referring to fig. 3, a method for dividing a split pattern into a first type of sparse pattern and a second type of sparse pattern includes the following steps:
Step S2041, obtaining split graphics to be judged from a plurality of split graphics of the layout to be corrected;
Step S2042, taking the splitting graph to be determined as a center, respectively obtaining a first determination area and a second determination area in the layout to be corrected, wherein the edge of the first determination area is a third size from the center of the splitting graph to be determined, the edge of the second determination area is a fourth size from the center of the splitting graph to be determined, and the third size is larger than the fourth size;
Step 2043, if no split pattern in the layout to be corrected is located in the first judgment area and no split pattern intersects with the edge of the first judgment area, the split pattern to be judged is a first type sparse pattern;
Step 2044, if there is a split pattern intersecting with the edge of the first determination area in the layout to be corrected, or if there is a split pattern located in the first determination area and located outside the second determination area, the split pattern to be determined is a second type sparse pattern;
Step 2045, if the split pattern in the layout to be corrected is located in the second determination area or intersects with the edge of the second determination area, the split pattern to be determined is a dense pattern.
The steps of the method for dividing the split pattern into the first type of sparse pattern and the second type of sparse pattern are described in detail below with reference to the accompanying drawings.
With continued reference to fig. 3 and 9, a split pattern to be determined is obtained from the split patterns 511 of the layout to be corrected.
For convenience of description, the first split pattern to be determined a, the second split pattern to be determined B, and the third split pattern to be determined C are described herein as split patterns to be determined, respectively.
With continued reference to fig. 3 and fig. 9, a first determination area and a second determination area are respectively obtained in the layout to be corrected with the splitting pattern to be determined as a center, the edge of the first determination area is a third size R3 from the center of the splitting pattern to be determined, the edge of the second determination area is a fourth size R4 from the center of the splitting pattern to be determined, and the third size R3 is greater than the fourth size R4.
In fig. 9, a first determination area and a second determination area centered on a first split pattern to be determined a, a second split pattern to be determined B, and a third split pattern to be determined C are shown by broken lines, respectively.
In this embodiment, the third dimension R3 ranges from 2.5 micrometers to 5 micrometers; the fourth dimension R4 ranges from 1.0 microns to 2.5 microns.
With continued reference to fig. 3 and fig. 9, if no split pattern in the layout to be corrected is located in the first determination area and no split pattern intersects with an edge of the first determination area, the split pattern to be determined is a first type sparse pattern; if a split pattern in the layout to be corrected is intersected with the edge of the first judging area or the split pattern is positioned in the first judging area and outside the second judging area, the split pattern to be judged is a second type sparse pattern; if the split pattern in the layout to be corrected is located in the second judging area or intersects with the edge of the second judging area, the split pattern to be judged is a dense pattern.
In this embodiment, for the first to-be-determined split pattern a, no split pattern in the layout to be corrected is located in the first determination area, and no split pattern intersects with an edge of the first determination area, so that the first to-be-determined split pattern a is a first type sparse pattern.
In this embodiment, for the second split pattern B to be determined, the split pattern in the layout to be corrected intersects with the edge of the first determination area, so that the second split pattern B to be determined is a second type sparse pattern.
In this embodiment, for the third splitting pattern C to be determined, the splitting pattern in the layout to be corrected intersects with the edge of the second determination area, so that the third splitting pattern C to be determined is a dense pattern.
Please continue to refer to fig. 2, and refer to fig. 10, to obtain information of reference position I of the split pattern in the plurality of split patterns except the layout to be corrected.
With continued reference to fig. 2, and with reference to fig. 11 to 12, setting an initial auxiliary pattern in the layout to be corrected according to the reference position I information, where the initial auxiliary pattern is located around the sparse pattern, and the size of the initial auxiliary pattern is smaller than or equal to the size of the split pattern (shown in fig. 7) at the corresponding reference position; and carrying out correction processing on the initial auxiliary graph for a plurality of times to obtain an auxiliary graph 603, wherein the auxiliary graph 603 and the split graph in the layout to be corrected form a corrected layout, and the simulated exposure graph of the corrected layout is provided with an exposure graph corresponding to the auxiliary graph.
The auxiliary pattern 603 has a corresponding exposure pattern, so that the pattern density around the sparse pattern can be improved, the non-uniformity of etching deviation caused by non-uniformity of the pattern density is further reduced, and the uniformity of the pattern density of the whole layout is improved; in addition, because the auxiliary graph 603 is set according to the reference position information of the split graph in a plurality of split graphs except the to-be-corrected graph, the multiple overlapping exposure of the split graph does not influence the appearance of the final exposure graph because of the specificity of the split graph of a CUT layer (trimming layer) in the LE+CUT process, so that the added auxiliary graph 603 can improve the graph density uniformity of the whole graph and the auxiliary graph 603 can not influence the appearance of the exposure graph after being exposed; secondly, the auxiliary graph is inserted around the sparse graph, so that the method has higher freedom degree compared with the dummy graph (dummy pattern) inserted around the sparse graph, and is more suitable for being used in the actual chip of the advanced node complex environment.
In this embodiment, the auxiliary pattern 603 and the split pattern 511 in the first split pattern 51 form a modified pattern, and an exposure pattern corresponding to the auxiliary pattern is included in a simulated exposure pattern of the modified pattern.
In this embodiment, please refer to fig. 4 for the several correction processing methods, which includes the following steps:
s2071, forming a first transition layout by the initial auxiliary graph and the split graph in the layout to be corrected;
S2072, performing conflict check on the first transition layout, taking the initial auxiliary graph as an intermediate auxiliary graph when the first transition layout has no conflict, and performing first deformation correction on the initial auxiliary graph to obtain the intermediate auxiliary graph when the first transition layout has conflict;
Step S2073, after the conflict check, replacing the initial auxiliary graph with the intermediate auxiliary graph to form a second transition layout;
S2074, performing simulated exposure on the second transition layout to obtain a simulated exposure pattern;
Step S2075, when the simulated exposure pattern has the exposure pattern corresponding to the intermediate auxiliary pattern, taking the intermediate auxiliary pattern as the auxiliary pattern;
step S2076, when the exposure pattern corresponding to the intermediate auxiliary pattern does not exist in the simulated exposure pattern, performing second deformation correction on the intermediate auxiliary pattern to obtain a transition auxiliary pattern;
Step S2077, after obtaining the transition auxiliary graph, replacing the initial auxiliary graph with the transition auxiliary graph to form an updated first transition layout;
And step S2078, performing conflict check again on the updated first transition layout to obtain an updated intermediate auxiliary graph and an updated second transition layout until an exposure graph corresponding to the intermediate auxiliary graph is arranged in the simulated exposure graph of the second transition layout, and taking the intermediate auxiliary graph as the auxiliary graph.
In this embodiment, the first deformation correction method for the initial auxiliary graph includes: one or more of clearing the initial assist feature that violates the reticle rule, clearing the initial assist feature that violates the etch rule, changing the size of the initial assist feature, and changing the shape of the initial assist feature.
In this embodiment, the initial auxiliary pattern violating the mask rule includes: the size of the initial auxiliary pattern is smaller than one or more of a preset line width, the distance between the adjacent initial auxiliary patterns is smaller than a preset distance, the distance between the initial auxiliary pattern and the split pattern is smaller than the preset distance, and the pattern area of the initial auxiliary pattern is smaller than the preset area.
In this embodiment, the initial auxiliary pattern violating the etching rule includes: the size of the initial assist feature is less than the photolithographic process limit.
In this embodiment, the second deformation correction method for the initial auxiliary graph includes: one or more of clearing the initial assist feature that violates the reticle rule, clearing the initial assist feature that violates the etch rule, changing the size of the initial assist feature, and changing the shape of the initial assist feature.
In this embodiment, before setting the initial auxiliary graph and after acquiring the sparse graph, the method further includes: taking any sparse graph as a center, acquiring a first correction area and a second correction area, wherein the first correction area has a first radius R1, the second correction area has a second radius R2, and the first radius R1 is smaller than the second radius R2.
The first correction area and the second correction area are used for limiting the position of the auxiliary graph, and the first correction area and the second correction area with different sizes can be selected, so that correction efficiency and accuracy are improved.
The first radius R1 has a size in the range of 1.0 to 2.5 microns; the second radius R2 has a size in the range of 2.5 microns to 5 microns. In this embodiment, the first radius R1 is the same as the fourth dimension R4, and the second radius R2 is the same as the third dimension R3.
In this embodiment, the initial auxiliary patterns include a first initial auxiliary pattern 601 and a second initial auxiliary pattern 602, where the first initial auxiliary pattern 601 is located around the corresponding sparse pattern, and the second initial auxiliary pattern 602 is located around the first initial auxiliary pattern 601 and the corresponding sparse pattern.
In this embodiment, the initial first auxiliary pattern 601 is located in the first correction area or intersects with the edge of the first correction area; the initial second auxiliary graphic 602 is located outside the first correction zone and within or intersecting the second correction zone edge. Specifically, the initial first auxiliary pattern 601 intersects with the first correction region edge; the initial second auxiliary graphic 602 is located outside the first correction region and intersects the second correction region edge.
In this embodiment, the auxiliary pattern includes a first auxiliary pattern and a second auxiliary pattern, where the first auxiliary pattern is located around the corresponding sparse pattern, and the second auxiliary pattern is located around the first auxiliary pattern and the corresponding sparse pattern. The first initial auxiliary pattern 601 is used to form the first auxiliary pattern, and the second initial auxiliary pattern 602 is used to form the second auxiliary pattern.
In this embodiment, correction is performed according to the severity of the influence of the sparse pattern on the etching deviation, that is, the sparse pattern is divided into two types of sparse patterns, namely, a first type sparse pattern and a second type sparse pattern, and meanwhile, the position where the auxiliary pattern is set is defined according to the distance from the sparse pattern, that is, the two correction areas, namely, the first correction area and the second correction area, are set. In other embodiments, only one type of sparse pattern may be defined, or only one correction region may be defined.
In this embodiment, the method for setting the initial auxiliary graph and the method for obtaining the auxiliary graph refer to fig. 5, and the method includes the following steps:
Step S2061, taking any first type sparse graph as a center, and acquiring the first correction area and the second correction area;
step S2062, setting the initial first auxiliary pattern around the first sparse pattern, where the initial first auxiliary pattern is located in the first correction area or intersects with the edge of the first correction area;
Step S2062, performing several times of correction processing on the initial first auxiliary graph around the first type sparse graph to obtain the first auxiliary graph around the first type sparse graph;
step S2063, after the first auxiliary pattern is acquired around the first type sparse pattern, setting the initial second auxiliary pattern around the first type sparse pattern, where the initial second auxiliary pattern is located outside the first correction area and is located in or intersects with the second correction area;
Step S2064, performing several times of correction processing on the initial second auxiliary graph around the first type sparse graph to obtain the second auxiliary graph around the first type sparse graph;
step S2065, after setting the auxiliary graphics around all the first type sparse graphics, obtaining the first correction area and the second correction area with any second type sparse graphics as a center;
Step S2066, setting the initial first auxiliary graph around the second type sparse graph;
step S2067, performing several times of correction processing on the initial first auxiliary graphics around the second type sparse graphics to obtain the first auxiliary graphics around the second type sparse graphics;
Step S2068, after setting the first auxiliary pattern around the second type sparse pattern, setting the initial second auxiliary pattern around the second type sparse pattern;
step S2069, performing several correction processes on the initial second auxiliary graphics around the second type sparse graphics to obtain the second auxiliary graphics around the second type sparse graphics.
In this embodiment, after the corrected layout is obtained, etching correction is further performed on the corrected layout, and an etching corrected layout is obtained.
The etching correction layout is used for compensating etching deviation, and the auxiliary graph 603 (shown in fig. 12) is provided with a corresponding exposure graph, so that the graph density around the sparse graph can be improved, the non-uniformity of the etching deviation caused by the non-uniformity of the graph density is further reduced, and the uniformity of the graph density of the whole layout is improved.
In this embodiment, optical proximity correction is further performed on the etching correction layout, and an optical correction layout is obtained. The optical correction layout is used as a mask layout for preparing a mask.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (15)
1. An optical proximity correction method, comprising:
Providing a cutting layout, wherein the cutting layout comprises a plurality of cutting patterns;
splitting the cutting layout into a plurality of splitting layouts, wherein each splitting layout is provided with a plurality of splitting graphs, and the splitting graphs in the splitting layouts are used for being combined into the cutting graphs;
Obtaining a layout to be corrected from a plurality of split layouts;
acquiring a sparse graph in the layout to be corrected, wherein the graph density of the sparse graph is lower than a preset density;
Acquiring reference position information of split graphics in a plurality of split layouts except the layout to be corrected;
setting an initial auxiliary graph in the layout to be corrected according to the reference position information, wherein the initial auxiliary graph is positioned around the sparse graph, and the size of the initial auxiliary graph is smaller than or equal to the size of the split graph at the corresponding reference position;
And carrying out correction processing on the initial auxiliary graph for a plurality of times to obtain an auxiliary graph, wherein the auxiliary graph and the split graph in the to-be-corrected graph form a correction layout, and the simulated exposure graph of the correction layout is provided with an exposure graph corresponding to the auxiliary graph.
2. The optical proximity correction method of claim 1, wherein the number of correction processing methods includes: forming a first transition layout by the initial auxiliary graph and the split graph in the layout to be corrected; performing conflict checking on the first transition layout, taking the initial auxiliary graph as an intermediate auxiliary graph when the first transition layout has no conflict, and performing first deformation correction on the initial auxiliary graph to obtain the intermediate auxiliary graph when the first transition layout has the conflict; after the conflict check, replacing the initial auxiliary graph with the intermediate auxiliary graph to form a second transition layout; performing simulated exposure on the second transition layout to obtain a simulated exposure pattern; when the simulated exposure pattern is provided with an exposure pattern corresponding to the intermediate auxiliary pattern, the intermediate auxiliary pattern is taken as the auxiliary pattern; when the simulation exposure pattern does not have the exposure pattern corresponding to the intermediate auxiliary pattern, performing second deformation correction on the intermediate auxiliary pattern to obtain a transition auxiliary pattern; after the transition auxiliary graph is obtained, replacing the initial auxiliary graph with the transition auxiliary graph to form an updated first transition layout; and performing conflict check again on the updated first transition layout to obtain an updated intermediate auxiliary graph and an updated second transition layout until an exposure graph corresponding to the intermediate auxiliary graph is arranged in the simulated exposure graph of the second transition layout, and taking the intermediate auxiliary graph as the auxiliary graph.
3. The optical proximity correction method of claim 2, wherein performing a first deformation correction method on the initial auxiliary pattern includes: one or more of clearing the initial assist feature that violates the reticle rule, clearing the initial assist feature that violates the etch rule, changing the size of the initial assist feature, and changing the shape of the initial assist feature.
4. The optical proximity correction method of claim 3 wherein the initial assist pattern that violates a reticle rule comprises: the size of the initial auxiliary pattern is smaller than one or more of a preset line width, the distance between the adjacent initial auxiliary patterns is smaller than a preset distance, the distance between the initial auxiliary pattern and the split pattern is smaller than the preset distance, and the pattern area of the initial auxiliary pattern is smaller than the preset area.
5. The optical proximity correction method of claim 3 wherein the initial assist pattern that violates an etch rule comprises: the size of the initial assist feature is less than the photolithographic process limit.
6. The optical proximity correction method according to claim 1, wherein the sparse pattern includes a first type sparse pattern and a second type sparse pattern, the first type sparse pattern having a pattern density lower than a pattern density of the second type sparse pattern; the initial auxiliary graph comprises a first initial auxiliary graph and a second initial auxiliary graph, the first initial auxiliary graph is positioned around the corresponding sparse graph, and the second initial auxiliary graph is positioned around the first initial auxiliary graph and the corresponding sparse graph; the auxiliary graphics comprise a first auxiliary graphics and a second auxiliary graphics, wherein the first auxiliary graphics are positioned around the corresponding sparse graphics, and the second auxiliary graphics are positioned around the first auxiliary graphics and the corresponding sparse graphics.
7. The optical proximity correction method of claim 6 wherein the method of acquiring the sparse pattern comprises: dividing the split pattern into a first type sparse pattern and a second type sparse pattern according to the distance between the split pattern in the layout to be corrected and the split pattern around the split pattern.
8. The optical proximity correction method of claim 7, further comprising, before setting an initial assist pattern and after acquiring the sparse pattern: and taking any sparse graph as a center, acquiring a first correction area and a second correction area, wherein the first correction area has a first radius, the second correction area has a second radius, and the first radius is smaller than the second radius.
9. The optical proximity correction method of claim 8, comprising: the initial first auxiliary graph is positioned in the first correction area or intersected with the edge of the first correction area; the initial second auxiliary pattern is located outside the first correction region and is located within or intersects the second correction region edge.
10. The optical proximity correction method of claim 8 wherein the first radius has a size in the range of 1.0 microns to 2.5 microns; the second radius has a size in the range of 2.5 microns to 5 microns.
11. The optical proximity correction method of claim 8 wherein the method of setting the initial assist pattern and the method of acquiring the assist pattern further comprise: taking any first type sparse graph as a center to acquire the first correction area and the second correction area; setting the initial first auxiliary graph around the first sparse graph; performing correction processing on the initial first auxiliary graph around the first type sparse graph for a plurality of times to obtain the first auxiliary graph around the first type sparse graph; after the first auxiliary graph is acquired around the first type sparse graph, setting the initial second auxiliary graph around the first type sparse graph; performing correction processing on the initial second auxiliary graph around the first type sparse graph for a plurality of times to obtain the second auxiliary graph around the first type sparse graph; after the auxiliary graphics are arranged around all the first type sparse graphics, taking any second type sparse graphics as a center to obtain the first correction area and the second correction area; setting the initial first auxiliary graph around the second type sparse graph; performing correction processing on the initial first auxiliary graph around the second type sparse graph for a plurality of times to obtain the first auxiliary graph around the second type sparse graph; after the first auxiliary graph is arranged around the second type sparse graph, the initial second auxiliary graph is arranged around the second type sparse graph; and carrying out correction processing on the initial second auxiliary graph around the second type sparse graph for a plurality of times to obtain the second auxiliary graph around the second type sparse graph.
12. The optical proximity correction method of claim 7, wherein the method of dividing the split pattern into the first type of sparse pattern and the second type of sparse pattern comprises: obtaining splitting graphs to be judged from a plurality of splitting graphs of the layout to be corrected; taking the splitting graph to be determined as a center, respectively acquiring a first determination area and a second determination area in the layout to be corrected, wherein the edge of the first determination area is a third size from the center of the splitting graph to be determined, the edge of the second determination area is a fourth size from the center of the splitting graph to be determined, and the third size is larger than the fourth size; if no split pattern is positioned in the first judging area and the no split pattern is intersected with the edge of the first judging area in the layout to be corrected, the split pattern to be judged is a first type sparse pattern; if a split pattern in the layout to be corrected is intersected with the edge of the first judging area or the split pattern is positioned in the first judging area and outside the second judging area, the split pattern to be judged is a second type sparse pattern; if the split pattern in the layout to be corrected is located in the second judging area or intersects with the edge of the second judging area, the split pattern to be judged is a dense pattern.
13. The optical proximity correction method of claim 12 wherein the third dimension ranges from 2.5 microns to 5 microns; the fourth dimension ranges from 1.0 microns to 2.5 microns.
14. The optical proximity correction method according to claim 1, characterized by further comprising, after obtaining the corrected layout: etching correction is carried out on the correction layout, and an etching correction layout is obtained; and performing optical proximity correction on the etching correction layout to obtain an optical correction layout.
15. The optical proximity correction method of claim 1, further comprising: providing a photoetching layout, wherein the photoetching layout comprises a plurality of photoetching patterns, and when the photoetching layout and the cutting layout are laminated, overlapping areas are formed between the plurality of cutting patterns and the plurality of photoetching patterns.
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