CN115729028B - Optical proximity correction method and mask - Google Patents
Optical proximity correction method and maskInfo
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- CN115729028B CN115729028B CN202111001006.7A CN202111001006A CN115729028B CN 115729028 B CN115729028 B CN 115729028B CN 202111001006 A CN202111001006 A CN 202111001006A CN 115729028 B CN115729028 B CN 115729028B
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Abstract
The optical proximity correction method comprises the steps of providing an original layout figure, obtaining an edge outline of the original layout figure, dividing the edge outline of the original layout figure into a plurality of segments, dividing the original layout figure by taking a first window as a unit, creating a second window by taking the first window as an inner window area, enabling the second window to comprise an outer window area of the first window, enabling the first window and the second window to be concentric, and executing accelerated iterative calculation on the edge placement errors of the segments of the inner and outer windows based on the information that the edge placement errors of the segments are influenced by correction amounts of adjacent segments, so as to correct the original layout figure, and obtain a target layout figure. The correction amount of each segment is determined to have higher precision because the correction amount of the adjacent segments is based on the information that the edge placement error of the segment is influenced by the correction amount of the adjacent segments when the original layout graph is corrected, namely, the correlation effect between the adjacent segments is considered.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to an optical proximity correction method and a mask.
Background
Photolithography is a technique of paramount importance in semiconductor fabrication technology, which enables transferring patterns from a reticle to a silicon wafer to form a semiconductor product that meets design requirements.
In semiconductor manufacturing, as the design dimensions continue to shrink, the diffraction effect of light becomes more and more pronounced, resulting in optical image degradation of the design pattern, and severe distortion of the actual lithographic pattern relative to the pattern on the reticle, resulting in the actual pattern being formed lithographically on the wafer and the design pattern being different, a phenomenon known as optical proximity effect (Optical Proximity Effect, OPE).
To correct for Optical proximity effects, an Optical proximity correction (Optical ProximityCorrection, OPC) is generated. The core idea of the optical proximity correction is to build an optical proximity correction model based on the consideration of canceling the optical proximity effect, and design a photomask pattern according to the optical proximity correction model, so that although the optical proximity effect occurs to the corresponding photomask pattern of the lithographic pattern, since the cancellation of the phenomenon is already considered when designing the photomask pattern according to the optical proximity correction model, the lithographic pattern after the lithography is close to the original layout pattern actually desired by the user.
In the existing optical proximity correction method, after an original layout pattern is provided, the whole optical proximity correction process comprises a plurality of loops, the original layout pattern is corrected for each loop to obtain an adjusted initial sub-pattern, an edge placement Error (EDGE PLACEMENT Error, EPE) is calculated, whether the correction is completed is judged by judging whether the edge placement Error reaches a standard or not, and finally the corrected pattern conforming to the standard is obtained.
Disclosure of Invention
The invention solves the problem of providing an optical proximity correction method and a mask plate so as to improve the accuracy of optical proximity correction.
In order to solve the above problems, the present invention provides an optical proximity correction method, which includes:
Providing an original layout figure;
Acquiring the edge contour of the original layout graph;
dividing the edge contour of the original layout graph into a plurality of segments;
dividing the original layout graph by taking a first window as a unit;
creating a second window by taking the first window as an inner window area, wherein the second window comprises an outer window area of the first window, and the first window and the second window are concentric;
And executing acceleration iterative computation on the edge placement errors of the segments in the inner region and the outer region of the window based on the information that the edge placement errors of the segments are influenced by the correction amounts of the adjacent segments, correcting the original layout graph, and obtaining a target layout graph.
Optionally, based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, performing accelerated iterative computation on the edge placement error of the segment in the inner region and the outer region of the window, correcting the original layout pattern, and obtaining the target layout pattern includes:
Providing a current layout figure, wherein the current layout figure is the original layout figure in the initial process;
traversing the first window of the current layout graph to obtain a traversed current first window and a corresponding second window;
Acquiring information of a target correction amount corresponding to each segment in a current first window based on information of influence of correction amount of each segment in the second window on edge placement errors of all segments in the second window;
Respectively shifting 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 is not traversed, acquiring a next first window as the current first window, and restarting the step of acquiring the information of the target correction amount corresponding to each segment in the current first window from the information based on 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 until the plurality of first windows are traversed, so as to acquire the corresponding corrected layout pattern;
When the first window in the current layout graph is determined to be traversed, judging whether a preset first iteration stop condition is reached;
When the first iteration stop condition is not met, taking the corrected layout pattern as the current layout pattern, traversing a first window of the current layout pattern, and restarting the step of acquiring the traversed current first window and a corresponding second window until the first iteration stop condition is met;
and when the first iteration stop condition is determined to be reached, the corrected layout pattern is used as the target layout pattern.
Optionally, the first iteration stop condition includes the number of iterations reaching a first threshold.
Optionally, the first threshold is 2-5 times.
Optionally, the step of obtaining information of the target correction amount corresponding to each segment in the current first window includes:
Obtaining the information of the current correction quantity of the segments in the second window, wherein the segments in the second window comprise other segments except the segments in the previous first window;
respectively applying corresponding current correction amounts to the segments in the second window to obtain a corrected second window graph;
Acquiring a simulated exposure pattern corresponding to the corrected second window pattern;
Comparing the corrected second window graph with the simulated exposure graph to obtain information of the edge placement error of the segments in the second window;
constructing an edge position interference matrix of the segment in the second window based on the current correction amount of the segment in the second window and the information of the edge placement error;
calculating information of a next correction amount of the segment in the second window based on the edge placement error information and the edge position interference matrix of the segment in the second window;
judging whether a preset second iteration stop condition is reached;
When the second iteration stop condition is not met, taking the next correction quantity of the segments in the second window as the current correction quantity of the segments in the second window, and respectively applying corresponding current correction quantities to the segments in the second window to acquire a corrected second window graph, wherein the step of restarting to execute until the second iteration stop condition is met;
And when the second iteration stop condition is determined to be met, acquiring information of the next correction quantity of each segment in the current first window from the next correction quantity of the segment in the second window, and taking the information as a target correction quantity of each segment in the current first window.
Optionally, the location interference matrix includes:
Diagonal elements representing edge placement errors generated by any one of the segments within the second window when a corresponding correction is applied to the segment, and
And off-diagonal elements representing the edge placement errors generated by any one of the segments within the second window, except for the segment within the second window, by applying a corresponding correction to the segment.
Optionally, the edge position interference matrix includes:
Wherein T ij denotes an element of an ith row and a jth column of the edge position interference matrix, The effect of the current correction amount Δf j of the j-th segment in the segments in the second window on the edge placement error Δepe i of the i-th segment is represented, and n represents the number of segments in the second window.
Optionally, the step of calculating information of a next correction amount of the segment within the second window includes:
calculating an inverse matrix of the edge position interference matrix;
and calculating information of the next correction quantity of the segment in the second window based on the inverse matrix and the edge placement error of the segment in the second window.
Optionally, in the step of obtaining the information of the target correction amount corresponding to each segment in the current first window, in the continuous at least two iterative processes, the inverse matrix of the edge position interference matrix is kept unchanged, and the edge placement error information of the segment in the second window is updated.
Optionally, the next correction of each segment in the second window is:
wherein Δepe j is the edge placement error of the jth segment in the second window, and Δf i is the next correction amount of the ith segment in the second window.
Optionally, the second iteration stop condition includes the number of iterations reaching a second threshold.
Optionally, the second threshold is 2-5 times.
Optionally, the first window is rectangular.
Optionally, the size of the first window is (1-3 μm) ×1-3 μm.
Optionally, the second window is rectangular.
Optionally, the size of the second window is (1-5 μm) ×1-5 μm.
Correspondingly, the embodiment of the invention also provides a mask plate, which comprises a mask plate pattern manufactured by adopting the optical proximity correction method.
Compared with the prior art, the technical scheme of the invention has the following advantages:
The optical proximity correction method comprises the steps of providing an original layout figure, obtaining an edge outline of the original layout figure, dividing the edge outline of the original layout figure into a plurality of segments, dividing the original layout figure by taking a first window as a unit, creating a second window by taking the first window as an inner window area, enabling the second window to comprise an outer window area of the first window, enabling the first window and the second window to be concentric, and executing accelerated iterative calculation on edge placement errors of segments of the inner and outer window areas based on information that the edge placement errors of the segments are influenced by correction amounts of adjacent segments, correcting the original layout figure, and obtaining a target layout figure. Because the original layout graph is corrected based on the information that the edge placement errors of the segments are influenced by the correction amounts of the adjacent segments, namely, the correlation effect between the adjacent segments is considered, the edge placement errors of the segments of the edge profile of the finally obtained target layout graph meet the requirements and have good critical dimension uniformity, and the determined correction amount of each segment has high precision.
Further, in the step of obtaining the information of the target correction amount corresponding to each segment in the current first window, in the continuous process of at least two iterations, the inverse matrix of the edge position interference matrix is kept unchanged, and the edge placement error information of the segment in the second window is updated, so that the operation time can be saved, and the efficiency of optical proximity correction is improved.
The attached drawings
FIG. 1 is a flow chart of an optical proximity correction method according to an embodiment of the invention;
FIG. 2 is a schematic diagram of an original layout pattern in accordance with an embodiment of the present invention;
FIG. 3 is a schematic diagram of a first window set in a current layout pattern in accordance with an embodiment of the present invention;
FIG. 4 is a flowchart corresponding to a step of correcting an original layout pattern to obtain a target layout pattern based on information that an edge placement error of a segment obtained by segmentation is influenced by a correction amount of an adjacent segment in an embodiment of the present invention;
FIG. 5 is a schematic diagram of a first window and a corresponding second window set in a current layout pattern according to an embodiment of the present invention;
FIG. 6 is a flowchart of a method for obtaining a target correction corresponding to each segment in a current first window according to an embodiment of the present invention;
Fig. 7 is a schematic diagram of a positional relationship between a neighboring first window and a neighboring second window in a current layout pattern according to an embodiment of the present invention.
Detailed Description
As known from the background art, the existing optical proximity correction method has the problem of lower precision.
The most widely used optical proximity correction method is a model-based optical proximity correction method at present, and the basic principle is that an exposure model based on specific photoetching conditions is established, an original layout figure is simulated to obtain a simulation error, then the original layout figure is divided into a plurality of corresponding segments according to a certain rule, the segments are offset compensated and re-simulated according to the simulation error, and a corrected layout with a simulation result consistent with a target layout is obtained after simulation and correction of a plurality of rounds.
The essence of the optical proximity correction method is mask optimization (Mask Optimization, MO). Existing optical proximity correction methods include global mask optimization (Global Mask Optimization, MO) methods and local mask optimization (Local Mask Optimization, LMO) methods.
The global mask optimization method obtains the correction amount of the segments by minimizing the cost function, and although the edge profile of the corrected layout graph has better critical dimension Uniformity (CD Uniformity), the edge placement error of some segments may not meet the standard requirement.
The local mask optimization method is to obtain the correction of each segment by minimizing the absolute value of the edge placement error of each segment, but the correction may cause larger fluctuation of the edge contour of the corrected layout pattern, so that the uniformity of the critical dimension is poor.
In order to solve the above problems, in the optical proximity correction method according to the embodiment of the present invention, the original layout pattern is corrected based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, that is, the correlation effect between the adjacent segments is considered, so that the edge placement errors of the segments of the edge profile of the final obtained target layout pattern all meet the requirements and have better critical dimension uniformity, and the final obtained target layout pattern has higher precision.
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Fig. 1 is a schematic flow chart of an optical proximity correction method in the implementation of the present invention.
Referring to fig. 1, step S101 is performed to provide an original layout pattern.
The original layout pattern is a preset pattern which needs to be generated in the mask plate and can be determined according to different semiconductor process requirements.
The original layout is built by adopting a rule-based target value resetting (retargeting) method.
The original layout graph is stored in an original layout file. The original layout file refers to a layout file containing design graphics, which is designed and formed by using an EDA tool. In general, the original layout file is a layout file that has passed the design rule verification (Design Rule Check, DRC).
In this embodiment, the file format of the original layout pattern is a GDS format. In other embodiments, the file format of the original layout graph may be other formats such as OASIS.
The original layout pattern comprises a plurality of initial sub-patterns. For example, referring to fig. 2, a plurality of initial sub-patterns 101 to 106 are respectively elongated, and the plurality of initial sub-patterns 101 to 106 are parallel to each other. In other embodiments, the initial sub-graph may have other shapes, such as an L-shape, and the invention is not limited in this regard.
With continued reference to fig. 1, step S102 is performed to obtain an edge contour of the original layout pattern.
And acquiring the edge contour of the original layout graph, namely acquiring the edge contour of a plurality of initial sub-graphs in the original layout graph.
In this embodiment, the edge profile of the original layout pattern is obtained by analyzing the original layout pattern.
In this embodiment, a plurality of initial sub-patterns in the original layout pattern are elongated, and edge outlines of the plurality of initial sub-patterns are rectangular correspondingly. In other embodiments, the outline of the initial sub-graph can also be a complex polygon formed by combining a plurality of rectangles or squares, such as an L-shape.
With continued reference to fig. 1, step S103 is performed to divide the edge contour of the original layout pattern into a plurality of segments.
And dividing the edge contour of the original layout graph into a plurality of segments, namely dividing the edge contour of the initial sub graph in the original layout graph into a plurality of segments.
In this embodiment, the length of each segment obtained by the segmentation is 20 nm-60 nm, and the length of each initial segment is different or at least partially different.
With continued reference to fig. 1, step S104 is performed to divide the original layout pattern in units of a first window.
Dividing the original layout graph by taking the first window as a unit, namely dividing the current layout graph into a plurality of corresponding areas by the plurality of first windows, and correcting the segments in the current layout graph by taking the first window obtained by dividing as a unit.
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 may also be a polygon or the like.
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) x (1-3 μm).
Referring to FIG. 3, a schematic diagram of a first window set in the current layout pattern is shown. Wherein the first window 30 includes a plurality of segments in one or more graphics to be corrected.
With continued reference to FIG. 1, step S105 is performed to create a second window for the intra-window region with the first window, the second window including an outer window region of the first window, the first window being concentric with the second window.
The corresponding second window is established with reference to the current first window. In this embodiment, the corresponding second window is established centered on the current first window. 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 taken as the inner area of the second window, and the portion of the second window except the first window is taken as the outer area of the window.
With continued reference to fig. 1, step S106 is executed to perform an accelerated iterative calculation on the edge placement error of the segment in the inner region and the outer region of the window based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, and correct the original layout pattern to obtain the target layout pattern.
The target layout pattern refers to an exposure pattern expected to meet the requirements of functions and production.
And performing one or more optical proximity corrections on the original layout pattern based on the information that the edge placement error of the segmented segment is affected by the correction amount of the adjacent segment, so as to obtain the target layout pattern, see fig. 4.
Referring to fig. 4, based on the information that the edge placement error of the segment is affected by the correction amount of the adjacent segment, performing an accelerated iterative calculation on the edge placement error of the segment in the inner region and the outer region of the window, correcting the original layout pattern, and acquiring the target layout pattern may specifically include:
step S401 is executed to provide the current layout pattern.
The current layout pattern is the original layout pattern or the corrected layout pattern obtained by the last iteration. The method comprises the steps of performing a first iteration, wherein the current layout figure is the original layout figure, and performing a second iteration to an N (N is an integer greater than or equal to 2) iteration, wherein the current layout figure is the corrected layout figure obtained in the last iteration.
Step S402 is executed, the first window of the current layout graph is traversed, and the traversed current first window and the corresponding second window are obtained.
In a specific implementation, the plurality of first windows in the current layout graph may be traversed according to a preset scanning sequence.
In this embodiment, the plurality of first windows in the current layout pattern are traversed in the order from left to right and from top to bottom. In other embodiments, the plurality of first windows in the current layout pattern may also be traversed in an order from top to bottom, from left to right, or from middle to four, which is not limited herein.
Referring to fig. 5, a schematic diagram of a first window and a corresponding second window is shown. Wherein, the dashed box 40 represents a first window, and the dashed box 50 represents a second window corresponding to the first window 40. The first windows 40 overlap the centers of the corresponding second windows 50, and the first windows 40 occupy the center regions of the corresponding second windows 50. The arrangement is such that the second window 50 includes not only segments having a neighbor effect with segments of the central region of the first window 40, but also segments having a neighbor effect with segments of the edge region of the first window 40.
The second window is preferably neither too large nor too small. When the second window is too large, the second window comprises a plurality of segments which do not have neighbor effect on the segments in the corresponding first window, the method is not beneficial to the follow-up acquisition of the target correction quantity in the current first window, the calculated quantity is obviously increased, and when the second window is too small, the segments which have neighbor effect on the segments positioned at the edge in the first window are excluded, so that the accuracy of the target correction quantity of the segments in the follow-up acquired first window is lower. Therefore, in this embodiment, the size of the second window is (1-5 μm).
Step S403 is executed, where information of the target correction amount corresponding to each segment in the current first window is obtained based on information of influence of the correction amount of each segment in the second window on the edge placement errors of all segments in the second window.
When the information of the target correction amount corresponding to each segment in the first window is acquired, the current first window is expanded to a second window taking the current first window as a central area, and for the segments in the current first window, not only the neighbor correlation effect of the segments in the central area of the first window is considered, but also the neighbor correlation effect of the segments at the edge of the first window is considered, so that the acquired target correction amount corresponding to each segment in the current first window is more accurate.
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, and refer to fig. 6 specifically.
With continued reference to fig. 4, step S404 is performed to offset the segments in the current first window by corresponding target correction amounts, respectively.
In a specific implementation, when the target correction amount corresponding to the segment in the current first window is obtained, the segment in the current first window is respectively offset by the corresponding target correction amount according to the information of the target correction amount of each segment.
Specifically, when the acquired target correction amount is a positive value, the corresponding segment is moved outward by a distance corresponding to the target correction amount, and when the acquired target correction amount is a negative value, the corresponding segment is moved outward by a distance corresponding to the absolute value of the target correction amount.
Step S405 is executed to determine whether the first window is traversed, step S406 may be executed if the determination result is negative, and step S407 may be executed if the determination result is negative.
Step S406 is executed to acquire the next first window as the current first window.
When it is determined that all the first windows in the current layout pattern are not traversed, taking the next first window as the current first window, and obtaining information of target correction amounts corresponding to each segment in the current first window to restart execution from step S403 based on information of influence of correction amounts of each segment in the second window on edge placement errors of all segments in the second window until traversing of a plurality of first windows in the current layout pattern is completed, so as to obtain corresponding corrected layout patterns.
Step S407 is executed to determine whether a preset first iteration stop condition is reached, when the determination result is no, step S408 may be executed, otherwise, step S409 may be executed.
In this embodiment, the first iteration stop condition is that the number of iterations reaches a preset first threshold.
The first threshold may be set according to actual process requirements. For example, the first threshold may be set to 2 to 5 times, etc.
And executing step S408, and taking the corresponding corrected layout pattern as the current layout pattern.
When it is determined that the first iteration stop condition is not met, the corrected layout graph obtained by the current iteration is used as the current layout graph, and the first window of the current layout graph is traversed from step S402, so that the traversed current first window and the corresponding second window are obtained to restart execution until the preset first iteration stop condition is met.
And executing step S409, wherein the corresponding corrected layout pattern is used as the target layout pattern.
And when the first iteration stopping condition is determined to be reached, outputting the corresponding corrected layout pattern obtained by executing the current iteration as a final target layout pattern.
Fig. 6 is a schematic flow chart of obtaining information of a target correction amount corresponding to each segment in a current first window based on information of influence of correction amounts of each segment in the second window on edge placement errors of all segments in the second window in the embodiment of the invention.
Referring to fig. 6, a step of obtaining a target correction amount corresponding to each segment in the current first window includes an iterative process, which may specifically include:
Step S601 is executed to acquire information of the current correction amount of the segment in the second window.
The current correction of the segment in the second window is the preset unit distance correction when the first sub-iteration is executed, and the current correction of the segment in the second window is the target correction obtained by executing the last iteration when the M-th iteration is executed (M is an integer greater than or equal to 2). The unit distance correction amount may be set according to actual needs or prior experience, and is not limited herein.
In this embodiment, the information of the current correction amount of the segment in the second window is obtained, which is the information of the current correction amounts of the segments in the second window graph except the segment in the previous first window. In other words, in an iteration process of obtaining the corresponding corrected layout pattern, when obtaining the target correction amount information of the segments in the first window and respectively shifting the segments in the first window to the corresponding target correction amounts, the positions of the segments in the first window will remain unchanged in the subsequent iteration process of obtaining the target correction amount information of the segments in other first windows.
For example, referring to fig. 7, for adjacent first windows 701 and 702, the respective second windows 701' and 702' have overlapping portions, and the second windows 702' include not only the first windows 702 but also the first windows 701. In an iterative process of obtaining the corresponding corrected layout pattern, after the target correction amounts of the segments in the first window 701 are obtained first and the segments in the first window 701 are respectively offset by the corresponding target correction amounts, the positions of the segments in the first window 701 will remain unchanged in a subsequent iterative process of obtaining the target correction amounts of the segments in the first window 702.
Step S602 is executed, where the corresponding current correction amounts are applied to the segments in the second window, so as to obtain a corrected second window graph.
When the current correction amount information of the segments in the second window is obtained, the segments in the second window are respectively shifted by the corresponding current correction amounts, so that a corrected second window graph is formed.
In this embodiment, the corresponding current correction amounts are applied to the segments in the second window respectively, and the corresponding current correction amounts are applied to the segments in the second window except the segment in the previous first window respectively.
Step S603 is executed to obtain a simulated exposure pattern corresponding to the corrected second window pattern.
The simulated exposure pattern is used for simulating the pattern formed on the wafer after the corrected second window pattern is subjected to the photoetching process.
In this embodiment, the shape of the initial sub-pattern in the original layout pattern unit is rectangular, and the shape of the corresponding pattern in the simulated exposure pattern is elliptical.
Step S604 is executed, where the corrected second window pattern is compared with the simulated exposure pattern, so as to obtain information of the edge placement error of the segment in the second window.
In this embodiment, the edge placement error of the segment in the second window graph may be calculated by using the following formula:
ΔEpei＝Di-Wi(1)
Wherein Δepe i represents an edge placement error of the ith segment in the second window, D i represents a position of the ith segment in the second window, and W i represents a position of the ith segment in the second window on the simulated exposure pattern.
Step S605 is executed to construct an edge position interference matrix of the segment in the second window based on the current correction amount of the segment in the second window pattern and the information of the edge placement error.
In this embodiment, the edge position interference matrix of the segments in the second window includes information of 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.
Specifically, in the position interference matrix, a diagonal element represents an edge placement error generated by any one of the segments in the second window when a corresponding correction amount is applied to the any one of the segments, and a non-diagonal element represents an edge placement error generated by any one of the segments in the second window when a corresponding correction amount is applied to any one of the segments in the first window, wherein the other segments except the any one of the segments in the first window.
As is clear from this, the position disturbance matrix includes not only the influence of the edge placement error itself when the current correction amount is corrected for any one of the segments, but also the influence of the edge placement errors for all the other segments.
The position interference matrix considers the neighbor (association) effect among all the segments in the segment neighborhood, so that the correction quantity of each determined segment is micro-movement, has higher precision, and is beneficial to enabling the correction of the original layout graph and the subsequent OPC iterative process to be converged rapidly.
Specifically, if the second window includes n segments, the corresponding position interference matrix may be expressed as:
Wherein T ij denotes an element of an ith row and a jth column of the edge position interference matrix, The influence of the current correction amount Δf j of the jth segment in the segments in the second window on the edge placement error Δepe i of the ith segment is represented, and n represents the number of segments in the second window graph.
Step S606 is executed to calculate information of a next correction amount of the segment in the second window pattern based on the edge placement error information of the segment in the second window and the edge position interference matrix.
When the corresponding current correction amount is applied to the segments in the second window and the edge placement error information and the edge position interference matrix of the segments in the second window are obtained, the information of the next correction amount of the segments in the second window graph can be calculated based on the edge placement error information and the edge position interference matrix of the segments in the second window.
Specifically, the following relationship is satisfied between the acquired 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:
according to the formula (3), the step of calculating the next correction of the segment in the second window comprises the steps of calculating an inverse matrix of the edge position interference matrix and calculating information of the next correction of the segment in the second window based on the inverse matrix and the edge placement error of the segment in the second window.
Specifically, the next correction amount of the segment in the second window may be obtained by calculating using the following formula:
wherein Δepe j is the edge placement error of the jth segment in the second window, and Δf i is the next correction amount of the ith segment in the second window.
Step S607 is performed to determine whether the preset second iteration stop condition is reached, and when the determination result is no, step S608 may be performed, otherwise, step S609 may be performed.
In this embodiment, the second iteration stop condition includes the number of iterations reaching a second threshold. Wherein the second threshold is 2-5 times.
Step S608 is executed to take the next correction amount of the segment in the second window pattern as the current correction amount of the segment in the second window pattern.
When it is determined that the preset second iteration stop condition is not reached, taking 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, and restarting execution from step S601 until the second iteration stop condition is reached.
Step S609 is executed to acquire information of a next correction amount of each segment in the current first window from the next correction amounts of segments in the second window graph, as a target correction amount of each segment in the current first window.
And when the second iteration stop condition is determined to be met, acquiring information of the next correction quantity of each segment in the current first window from the next correction quantity of the segment in the second window, and taking the information as a target correction quantity of each segment in the current first window.
In this embodiment, in the step of obtaining the information of the target correction amount corresponding to each segment in the current first window, in the continuous process of at least two iterations, the inverse matrix of the edge position interference matrix is kept unchanged, and the edge placement error information of the segment in the second window is updated, so as to save the calculation amount and increase the calculation speed.
As is clear from the above description of step S601 to step S609, when calculating the target correction amount of each segment in each first window, the first window is expanded to a corresponding second window, so that the second window includes not only the segments having the neighbor correlation effect with the segments of the central area of the first window, but also the segments having the neighbor correlation effect with the segments of the edge area of the first window, and the accuracy of the obtained target correction amounts of all the segments in the first window can be improved.
Correspondingly, the embodiment of the invention also provides a mask plate, which comprises a mask plate pattern manufactured by adopting the optical proximity correction method. The optical proximity correction method is described in the foregoing parts, and will not be described in detail.
The mask plate is used for exposing the photoresist on the wafer as a mask to form photoresist patterns of all chip areas on the wafer, and the chip areas of the wafer can be etched by the photoresist patterns, so that semiconductor structures such as a grid electrode, a metal interconnection line or a conductive plug and the like are formed in the chip areas of the wafer.
According to the embodiment, the obtained target layout pattern is adopted, and the original layout pattern is corrected based on the information that the edge placement error of the segment is influenced by the correction amount of the adjacent segment, namely, the correlation effect between the adjacent segments is considered, so that the edge placement error of the segment of the edge profile of the finally obtained target layout pattern meets the requirements and has good critical dimension uniformity, the determined correction amount of each segment has higher precision, and the pattern transfer precision is correspondingly improved.
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 (17)
1. An optical proximity correction method, comprising:
Providing an original layout figure;
Acquiring the edge contour of the original layout graph;
dividing the edge contour of the original layout graph into a plurality of segments;
dividing the original layout graph by taking a first window as a unit;
creating a second window by taking the first window as an inner window area, wherein the second window also comprises an outer window area of the first window, and the first window and the second window are concentric;
and executing accelerated iterative computation on the edge placement errors of the segments in each first window based on the information that the edge placement errors of each segment in the corresponding second window are influenced by the correction amounts of the adjacent segments, correcting the original layout graph, and obtaining the target layout graph.
2. The optical proximity correction method according to claim 1, wherein the step of performing an accelerated iterative calculation on the edge placement errors of the segments in the respective first windows based on information that the edge placement errors of each segment in the corresponding second window are affected by the correction amounts of the adjacent segments, correcting the original layout pattern, and obtaining the target layout pattern includes:
Providing a current layout figure, wherein the current layout figure is the original layout figure in the initial process;
traversing the first window of the current layout graph to obtain a traversed current first window and a corresponding second window;
Acquiring information of a target correction amount corresponding to each segment in a current first window based on information of influence of correction amount of each segment in the second window on edge placement errors of all segments in the second window;
Respectively shifting 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 is not traversed, acquiring a next first window as the current first window, and restarting the step of acquiring the information of the target correction amount corresponding to each segment in the current first window from the information based on 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 until the plurality of first windows are traversed, so as to acquire the corresponding corrected layout pattern;
When the first window in the current layout graph is determined to be traversed, judging whether a preset first iteration stop condition is reached;
When the first iteration stop condition is not met, taking the corrected layout pattern as the current layout pattern, traversing a first window of the current layout pattern, and restarting the step of acquiring the traversed current first window and a corresponding second window until the first iteration stop condition is met;
and when the first iteration stop condition is determined to be reached, the corrected layout pattern is used as the target layout pattern.
3. The optical proximity correction method of claim 2, wherein the first iteration stop condition includes a 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 acquiring information of the target correction amount corresponding to each segment in the current first window includes:
Obtaining the information of the current correction quantity of the segments in the second window, wherein the segments in the second window comprise other segments except the segments in the previous first window;
respectively applying corresponding current correction amounts to the segments in the second window to obtain a corrected second window graph;
Acquiring a simulated exposure pattern corresponding to the corrected second window pattern;
Comparing the corrected second window graph with the simulated exposure graph to obtain information of the edge placement error of the segments in the second window;
constructing an edge position interference matrix of the segment in the second window based on the current correction amount of the segment in the second window and the information of the edge placement error;
calculating information of a next correction amount of the segment in the second window based on the edge placement error information and the edge position interference matrix of the segment in the second window;
judging whether a preset second iteration stop condition is reached;
When the second iteration stop condition is not met, taking the next correction quantity of the segments in the second window as the current correction quantity of the segments in the second window, and respectively applying corresponding current correction quantities to the segments in the second window to acquire a corrected second window graph, wherein the step of restarting to execute until the second iteration stop condition is met;
And when the second iteration stop condition is determined to be met, acquiring information of the next correction quantity of each segment in the current first window from the next correction quantity of the segment in the second window, and taking the information as a target correction quantity of each segment in the current first window.
6. The optical proximity correction method according to claim 5, wherein the position interference matrix includes:
diagonal elements representing edge placement errors generated by any edge when a corresponding correction is applied to any one of the segments within the second window, and
And off-diagonal elements representing the edge placement errors generated by any one of the segments within the second window, except for the segment within the second window, by applying a corresponding correction to the segment.
7. The optical proximity correction method according to claim 5, wherein the edge position interference matrix includes:
Wherein T ij denotes an element of an ith row and a jth column of the edge position interference matrix, The effect of the current correction amount Δf j of the j-th segment in the segments in the second window on the edge placement error Δepe i of the i-th segment is represented, and 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 a next correction amount of the segment within the second window includes:
calculating an inverse matrix of the edge position interference matrix;
and calculating information of the next correction quantity of the segment in the second window based on the inverse matrix and the edge placement error of the segment in the second window.
9. The optical proximity correction method according to claim 8, wherein in the step of acquiring 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 maintained unchanged and the edge placement error information of the segment in the second window is updated during at least two successive iterations.
10. The optical proximity correction method of claim 8, wherein the next correction amount for each segment in the second window is:
wherein Δepe j is the edge placement error of the jth segment in the second window, and Δf i is the next correction amount of the ith segment in the second window.
11. The optical proximity correction method of claim 5, wherein the second iteration stop condition includes a number of iterations reaching a second threshold.
12. The method of claim 11, wherein the second threshold is 2-5 times.
13. The optical proximity correction method of claim 2, wherein the first window is rectangular.
14. The method of claim 13, wherein the first window has a size of (1-3 μm).
15. The optical proximity correction method according to claim 2, wherein the second window is rectangular.
16. The method of claim 15, wherein the second window has a size of (1-5 μm).
17. A reticle comprising a reticle pattern fabricated by the optical proximity correction method of any one of claims 1 to 16.
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