Optical proximity correction method and device
By detecting EPE in the optical proximity correction method and correcting only the EPE near the EPE, the problem of waste of optical proximity correction time and resource in the prior art is solved, and time and resource savings are achieved.
Patent Information
- Application Number
- CN202410170220.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-06
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, the optical proximity correction method has problems of time and resource waste in the lithography process. Although the mask version has been corrected, subsequent iteration calculations are still performed according to the original set number of iterations.
By detecting the EPE after each OPC iteration, it is determined whether there is an EPE and does not reach the maximum number of iterations. Only the graphs near the EPE are corrected, and the new graphs to be corrected are selected for the next iteration until the EPE disappears or the maximum number of iterations is reached.
While ensuring that the accuracy of optical proximity correction remains unchanged, the execution time and resource consumption of optical proximity correction are significantly reduced, and the cost is reduced.
Smart Images
Figure CN120447299A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to an optical proximity correction method and device. Background Art
[0002] Before the photolithography process begins, the design pattern must be copied onto a mask using specialized equipment. The pattern on the mask is then transferred to the silicon wafer surface using the photolithography equipment, creating a semiconductor product that meets the design requirements. However, as design dimensions continue to shrink, the diffraction effect of light becomes increasingly pronounced, causing the actual pattern formed by the photolithography to be severely distorted relative to the pattern on the mask. This phenomenon is known as the optical proximity effect (OPE).
[0003] In order to solve the above problem, it is necessary to perform optical proximity correction (OPC) on the mask, that is, to perform pre-modification compensation processing on the mask before lithography so that the amount of modification compensation can just make up for the error caused by the optical proximity effect.
[0004] Currently, the industry primarily uses model-based OPC for iterative OPC mask calculations. This involves setting the number of iterations. Each iteration corrects all patterns in the OPC mask according to the set number, and the same number of OPC iterations is performed on all patterns in the layout. Experiments have shown that OPC iteration time is linearly proportional to the number of iterations. Furthermore, even after the OPC mask has been fully corrected, subsequent iterations will still be performed according to the set number of iterations, wasting time and resources. Summary of the Invention
[0005] An object of the present invention is to provide an optical proximity correction method and apparatus, which can significantly reduce the execution time of the optical proximity correction while ensuring that the accuracy of the optical proximity correction remains unchanged.
[0006] To solve the above technical problems, according to a first aspect of the present invention, there is provided an optical proximity correction method, comprising the following steps:
[0007] S1: Perform the first OPC iteration;
[0008] S2: Perform EPE check on the OPC iteration result;
[0009] S3: Determine whether there is an EPE and whether the number of iterations has not reached the set maximum number. If there is an EPE and the number of iterations has not reached the set maximum number, a region to be corrected is delineated with the point where the EPE exists as the center, and the figure that contacts the region to be corrected is used as the new figure to be corrected and the next OPC iteration is performed, and then return to S2; if there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is terminated.
[0010] Optionally, the area to be corrected is a square area with the point where the EPE exists as the center and a set length as the side length; or, the area to be corrected is a circular area with the point where the EPE exists as the center and a set length as the radius.
[0011] Optionally, the set length is between 1 μm and 3 μm.
[0012] Optionally, the set length is 2 μm.
[0013] Optionally, in S3, the remaining patterns of all the patterns in the mask layout except the new pattern to be corrected are incorporated into the SRAF as auxiliary patterns to assist the next OPC iteration.
[0014] To solve the above technical problems, according to a second aspect of the present invention, an optical proximity correction device is provided, comprising:
[0015] OPC iteration module: performs OPC iteration;
[0016] EPE detection module: performs EPE detection on the OPC iteration results after each OPC iteration;
[0017] Determination module: Determine whether there is EPE and whether the number of iterations has not reached the set maximum number. If there is EPE and the number of iterations has not reached the set maximum number, the next OPC iteration is performed. If there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is terminated.
[0018] Target resetting module: a region to be corrected is defined with the point where the EPE exists as the center, and the graphics that touch the region to be corrected are redefined as the new graphics to be corrected for the next OPC iteration.
[0019] Optionally, the target resetting module demarcates a square area with a set side length with the point where the EPE exists as the center as the area to be corrected; or, the target resetting module demarcates a circular area with a set radius with the point where the EPE exists as the center as the area to be corrected.
[0020] Optionally, the set side length or the set radius is between 1 μm and 3 μm.
[0021] Optionally, the set side length or the set radius is 2 μm.
[0022] Optionally, the target resetting module incorporates the remaining patterns of all the patterns in the mask layout except the new pattern to be corrected into the SRAF as auxiliary patterns to assist the next OPC iteration.
[0023] In summary, in the optical proximity correction method and device provided by the present invention, the first OPC iteration is first performed, followed by an EPE detection. It is then determined whether an EPE exists and whether the number of iterations has not reached the set maximum number. If an EPE exists and the number of iterations has not reached the set maximum number, an area to be corrected is delineated with the point where the EPE exists as the center. The figure that contacts the area to be corrected is used as the new figure to be corrected and the next OPC iteration is performed. The OPC iteration is then returned to the EPE detection step. If no EPE exists or the number of iterations has reached the set maximum number, the OPC iteration is terminated. The present invention detects the EPE after each OPC iteration to determine whether another iteration is required. Except for the first OPC iteration, only the figure to be corrected near the EPE is corrected during each OPC iteration. While ensuring that the OPC accuracy remains unchanged, the execution time of the OPC can be reduced, thereby saving time and resources and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.
[0025] Figure 1 FIG. 4 is a flow chart of an optical proximity correction method provided by one embodiment of the present invention.
[0026] Figure 2 4 is a structural block diagram of an optical proximity correction device provided by one embodiment of the present invention. DETAILED DESCRIPTION
[0027] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.
[0028] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense including "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense including "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense including "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features.
[0029] The optical proximity correction method in the prior art is to perform a set number of OPC iterations on all graphics in the mask layout. Even if some graphics have been corrected, iterations still need to be performed. Even if the mask has been corrected, subsequent iterative calculations will still be performed according to the originally set number of iterations. This makes the entire optical proximity correction time-consuming, wastes time and resources, and leads to relatively high costs.
[0030] The optical proximity correction method provided by the present invention determines whether to perform the next iteration based on the result of each OPC iteration, and the next iteration selects the graphics near the EPE in the previous iteration as the new graphics to be corrected, and there is no need to correct all graphics. Under the premise of ensuring that the OPC accuracy remains unchanged, the execution time of OPC can be reduced, thereby saving time and resources and reducing costs.
[0031] Figure 1 This is a flow chart of an optical proximity correction method provided by an embodiment of the present invention. Figure 1 As shown, the optical proximity correction method provided by the embodiment of the present invention includes the following steps:
[0032] Step S1: perform the first OPC iteration;
[0033] Step S2: Perform EPE check on the OPC iteration result;
[0034] Step S3: Determine whether there is an EPE and whether the number of iterations has not reached the set maximum number. If there is an EPE and the number of iterations has not reached the set maximum number, a region to be corrected is delineated with the point where the EPE exists as the center, and the figure that contacts the region to be corrected is used as the new figure to be corrected and the next OPC iteration is performed, and then return to S2; if there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is terminated.
[0035] In step S1 , the first OPC iteration is performed.
[0036] For example, a model-based OPC correction method can be used to perform OPC iterations. This method typically undergoes multiple corrections (each correction is called an iteration) until the corrected simulation result matches the target pattern, or the error between the corrected simulation value and the target value is within an allowable range. In this embodiment, a single OPC iteration is performed using the model-based OPC correction method. All patterns in the mask layout are corrected in this iteration.
[0037] In step S2, an EPE check is performed on the OPC iteration result.
[0038] The OPC iteration result in step S1 is tested for EPE (Edge Placement Error). EPE is the difference between the edge of the photoresist pattern after exposure simulated by the photolithography software and the designed pattern.
[0039] In step S3, it is determined whether there is an EPE and whether the number of iterations has not reached the set maximum number. If there is an EPE and the number of iterations has not reached the set maximum number, an area to be corrected is delineated with the point where the EPE exists as the center, and the figure that contacts the area to be corrected is used as a new figure to be corrected and the next OPC iteration is performed, and the process returns to step S2; if there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is terminated.
[0040] A determination is made as to whether an EPE exists and the number of iterations has not reached the maximum number of preset times. If an EPE exists and the number of iterations has not reached the maximum number of preset times, a new pattern to be corrected is determined and the next OPC iteration is performed. In this embodiment, a region to be corrected is defined with the point where the EPE exists as the center, and all patterns that contact the region to be corrected are considered new patterns to be corrected. Contact with the region to be corrected means being within the region to be corrected or partially overlapping with the region to be corrected.
[0041] In one embodiment of the present invention, the area to be corrected is a square area centered at the point where the EPE exists and with a set length as the side length. The set length can be determined based on actual needs. For example, the selected set length needs to ensure that the graphics with EPE will be corrected next time, but will not include or will not include too many graphics that have already been corrected, so as not to increase unnecessary correction time. Exemplarily, the set length is between 1μm and 3μm, and preferably, the set length is 2μm.
[0042] In another embodiment of the present invention, the area to be corrected is a circular area centered at the point where the EPE exists and with a set length as the radius. The set length can be determined based on actual needs. For example, the selected set length needs to ensure that the graphics with EPE will be corrected next time, but will not include or will not include too many graphics that have already been corrected, so as not to increase unnecessary correction time. Exemplarily, the set length is between 1μm and 3μm, and preferably, the set length is 2μm.
[0043] In other embodiments, the area to be corrected may also be other shapes known to those skilled in the art. The present invention is not limited to this and may be selected according to actual needs. For example, a shape that is relatively simple to correct may be selected as the shape of the area to be corrected, that is, the selected shape will not increase the difficulty of correction.
[0044] In one embodiment of the present invention, the graphics near the EPE are used as new graphics to be corrected in the next iteration. At the same time, the remaining graphics of all the graphics in the mask plate except the new graphics to be corrected can be incorporated into the SRAF (Sub-Resolution Assistant Feature) as auxiliary graphics to assist the next OPC iteration.
[0045] Determine whether there is an EPE and whether the number of iterations has not reached the set maximum number. If there is no EPE or the number of iterations has reached the set maximum number, no further OPC iteration is required, and the OPC iteration ends.
[0046] In this step, the next iteration is performed using the new pattern to be corrected, and then the process returns to step S2. That is, after each OPC iteration, the OPC iteration result is checked for EPE. If EPE exists and the number of iterations has not reached the maximum number, a new pattern to be corrected is determined and the next OPC iteration is performed. If EPE does not exist or the number of iterations has reached the maximum number, the OPC iteration ends.
[0047] In this embodiment, after each OPC iteration, an EPE check is performed on the OPC iteration result to determine whether the next OPC iteration is required and to determine the graphics to be corrected (i.e., the new graphics to be corrected) in the next OPC iteration. Compared with the prior art method of performing OPC iteration on all graphics in the layout, the number of graphics to be corrected is reduced. Compared with the prior art method of performing iterations according to a set number of iterations, the iteration is terminated if no EPE exists or the number of iterations reaches a set maximum number, thereby reducing the number of iterations. Therefore, while maintaining OPC accuracy, the execution time of OPC can be reduced, thereby saving time and resources and reducing costs.
[0048] Table 1
[0049]
[0050] Table 1 is a comparison of the optical proximity correction method in the prior art and the optical proximity correction method provided by an embodiment of the present invention, wherein iteration 1 refers to the first iteration and iteration 2 refers to the second iteration. The number of graphics (i.e., all graphics in the layout) in the first iteration of the prior art and the present invention is the same, the iteration time is also the same, and the number of EPEs after the first iteration is also the same. The number of graphics in the second iteration of the prior art is the same as the number of graphics in the first iteration, that is, all graphics in the layout are iterated, and the number of iterated graphics is 8181329, and the time spent is 3327s. In the present invention, only the graphics near the EPE after the first iteration are iterated, and the number of iterated graphics is only 678, and the time spent is only 197s. There is no EPE after the second iteration, so the iteration is terminated. Comparing the prior art with the present invention, it can be seen that the optical proximity correction method provided by the present invention saves the execution time of OPC. Moreover, since the number of graphics in the first iteration is the same and the time spent is the same, and Table 1 is an explanation based on 2 iterations as an example, it has saved nearly half of the time. If the number of iterations is relatively large, the time saved will be more.
[0051] In the optical proximity correction method provided by the present invention, the first OPC iteration is first performed, followed by an EPE detection. It is then determined whether an EPE exists and whether the number of iterations has not reached a set maximum number. If an EPE exists and the number of iterations has not reached the set maximum number, a correction area is demarcated with the point where the EPE exists as the center. The figure that contacts the correction area is used as the new correction area and the next OPC iteration is performed. The OPC iteration is then returned to the EPE detection step. If no EPE exists or the number of iterations has reached the set maximum number, the OPC iteration is terminated. The present invention detects the EPE after each OPC iteration to determine whether another iteration is needed. Except for the first OPC iteration, only the correction area near the EPE is corrected during each OPC iteration. While maintaining the OPC accuracy, the OPC execution time can be reduced, thereby saving time and resources and reducing costs.
[0052] Correspondingly, the present invention also provides an optical proximity correction device for performing the optical proximity correction method described above.
[0053] Figure 2 4 is a structural block diagram of an optical proximity correction device provided by one embodiment of the present invention. Figure 2 according to Figure 1 The sequence of the method shown uses arrowed lines to represent the relationship between the components of the optical proximity correction device. Figure 2As shown, the optical proximity correction device provided by the embodiment of the present invention includes an OPC iteration module 11 , an EPE detection module 12 , a determination module 13 and a target resetting module 14 .
[0054] The OPC iteration module 11 is used to perform OPC iteration; the EPE detection module 12 performs EPE detection on the OPC iteration result after each OPC iteration; the determination module 13 determines whether there is EPE and whether the number of iterations has not reached the set maximum number. If there is EPE and the number of iterations has not reached the set maximum number, the next OPC iteration is performed; if there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is ended; the target resetting module 14 demarcates an area to be corrected with the point where the EPE exists as the center, and redefines the figure that contacts the area to be corrected as the new figure to be corrected for the next OPC iteration.
[0055] Please refer to Figure 1 and Figure 2 As shown, first, the OPC iteration module 11 is used to perform the first OPC iteration, and then the EPE detection module 12 is used to perform an EPE check on the OPC iteration result. Then, the determination module 13 is used to determine whether EPE exists and whether the number of iterations has not reached the set maximum number. If EPE exists and the number of iterations has not reached the set maximum number, the target resetting module 14 is used to define a to-be-corrected area with the point where EPE exists as the center, and the figure that contacts the to-be-corrected area is re-determined as the new to-be-corrected figure for the next OPC iteration. Then, the OPC iteration module 11 is used to perform an OPC iteration, and the process returns to the step of performing an EPE check on the OPC iteration result using the EPE detection module 12. If EPE does not exist or the number of iterations reaches the set maximum number, the OPC iteration is terminated.
[0056] In one embodiment of the present invention, the target resetting module 14 demarcates a square area with a set side length with the point where the EPE exists as the center as the area to be corrected. The set side length can be determined according to actual needs. For example, the selected set length needs to ensure that the graphics with EPE will be corrected next time, but will not include or will not include too many graphics that have already been corrected, so as not to increase unnecessary correction time. Exemplarily, the set side length is between 1μm and 3μm. Preferably, the set side length is 2μm.
[0057] In another embodiment of the present invention, the target resetting module 14 defines a circular area with a set radius as the area to be corrected with the point where the EPE exists as the center. The set radius can be determined according to actual needs. For example, the selected set length needs to ensure that the graphics with EPE will be corrected next time, but will not include or will not include too many graphics that have already been corrected, so as not to increase unnecessary correction time. Exemplarily, the set radius is between 1μm and 3μm, and preferably, the set radius is 2μm.
[0058] In other embodiments, the target resetting module 14 can also define other shapes known to those skilled in the art as the area to be corrected with the point where the EPE exists as the center. The present invention is not limited to this and can be selected according to actual needs. For example, a shape that is relatively simple to correct can be selected as the shape of the area to be corrected, that is, the selected shape will not increase the complexity of the correction.
[0059] In one embodiment of the present invention, the target resetting module 14 uses the graphics near the EPE as the new graphics to be corrected in the next iteration. At the same time, the remaining graphics of all the graphics in the mask plate except the new graphics to be corrected can be incorporated into the SRAF (Sub-Resolution Assistant Feature) as auxiliary graphics to assist the next OPC iteration.
[0060] In summary, in the optical proximity correction method and device provided by the present invention, the first OPC iteration is first performed, followed by an EPE detection. It is then determined whether an EPE exists and whether the number of iterations has not reached the set maximum number. If an EPE exists and the number of iterations has not reached the set maximum number, an area to be corrected is delineated with the point where the EPE exists as the center. The figure that contacts the area to be corrected is used as the new figure to be corrected and the next OPC iteration is performed. The OPC iteration is then returned to the EPE detection step. If no EPE exists or the number of iterations has reached the set maximum number, the OPC iteration is terminated. The present invention detects the EPE after each OPC iteration to determine whether another iteration is required. Except for the first OPC iteration, only the figure to be corrected near the EPE is corrected during each OPC iteration. While ensuring that the OPC accuracy remains unchanged, the execution time of the OPC can be reduced, thereby saving time and resources and reducing costs.
[0061] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.
Claims
1. An optical proximity correction method, characterized in that: The following steps are involved: S1: Perform the first OPC iteration; S2: Perform EPE check on the OPC iteration result; S3: Determine whether there is an EPE and whether the number of iterations has not reached the set maximum number. If there is an EPE and the number of iterations has not reached the set maximum number, a region to be corrected is delineated with the point where the EPE exists as the center, and the figure that contacts the region to be corrected is used as a new figure to be corrected and the next OPC iteration is performed, and then return to S2; If there is no EPE or the number of iterations reaches the set maximum number, the OPC iteration ends.
2. The optical proximity correction method according to claim 1, wherein: The area to be corrected is a square area with the point where the EPE exists as the center and the set length as the side length; or, the area to be corrected is a circular area with the point where the EPE exists as the center and the set length as the radius.
3. The optical proximity correction method according to claim 2, wherein: The set length is between 1 μm and 3 μm.
4. The optical proximity correction method according to claim 3, wherein: The set length is 2 μm.
5. The optical proximity correction method according to any one of claims 1 to 4, characterized in that: In S3, the remaining patterns of all the patterns in the mask layout except the new pattern to be corrected are incorporated into the SRAF as auxiliary patterns to assist the next OPC iteration.
6. An optical proximity correction device, characterized in that: include: OPC iteration module: performs OPC iteration; EPE detection module: performs EPE detection on the OPC iteration results after each OPC iteration; Determination module: Determine whether there is EPE and whether the number of iterations has not reached the set maximum number. If there is EPE and the number of iterations has not reached the set maximum number, the next OPC iteration is performed. If there is no EPE or the number of iterations has reached the set maximum number, the OPC iteration is terminated. Target resetting module: a region to be corrected is defined with the point where the EPE exists as the center, and the graphics that touch the region to be corrected are redefined as the new graphics to be corrected for the next OPC iteration.
7. The optical proximity correction device according to claim 6, wherein: The target resetting module demarcates a square area with a set side length with the point where the EPE exists as the center as the area to be corrected; or, the target resetting module demarcates a circular area with a set radius with the point where the EPE exists as the center as the area to be corrected.
8. The optical proximity correction device according to claim 7, wherein: The set side length or the set radius is between 1 μm and 3 μm.
9. The optical proximity correction device according to claim 8, wherein: The set side length or the set radius is 2 μm.
10. The optical proximity correction device according to any one of claims 6 to 9, characterized in that The target resetting module incorporates the remaining patterns of all the patterns in the mask layout except the new pattern to be corrected into the SRAF as auxiliary patterns to assist the next OPC iteration.