Method for reducing correction time of optical proximity effect

Abstract

The invention provides a method for reducing optical proximity correction time, which comprises the following steps of: providing an initial target graph, performing OPC (Optical Proximity Correction) on the initial target graph to obtain a correction mask plate of the initial target graph, and comparing the correction mask plate of the initial target graph with the initial target graph to obtain a deviation table; a to-be-corrected target pattern is provided, the to-be-corrected target pattern is the same as the initial target pattern, the deviation table is imported into the OPC formula, OPC correction is conducted on the to-be-corrected target pattern, and the corrected mask plate of the to-be-corrected target pattern is obtained. According to the method for reducing the correction time of the optical proximity effect, after OPC is carried out on the initial target graph, a deviation table between a correction mask plate of the initial target graph and the initial target graph is obtained, and when to-be-corrected target graphs of the same graph are corrected subsequently, the deviation table is imported into an OPC formula to be corrected, so that the correction time of the optical proximity effect is shortened. The correction time is greatly reduced, and the OPC correction efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photolithography and relates to a method for reducing optical proximity effect correction time. Background Art

[0002] As process nodes continue to shrink, Optical Proximity Correction (OPC) technology is an indispensable part of improving line width accuracy. In advanced nodes, model-based OPC not only has better accuracy in small line width correction, but also can detect hot spots early through model simulation, becoming the mainstream optical proximity correction method in the industry.

[0003] However, model-based OPC has a disadvantage that cannot be ignored, which is that the correction time is too long. In order to improve accuracy, the OPC model must simulate the entire chip (full chip) every time it is corrected, and calculate whether the edge placement error (EPE) of each graphic is in place before correcting the mask. This usually requires several cycles, which also means that a lot of resources and time are required.

[0004] Therefore, how to provide a method for reducing the optical proximity effect correction time so as to reduce the OPC correction time and improve the correction efficiency has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for reducing the optical proximity effect correction time, so as to solve the problem of long OPC correction time in the prior art.

[0006] To achieve the above object and other related objects, the present invention provides a method for reducing the optical proximity effect correction time, comprising the following steps:

[0007] Providing an initial target pattern, performing OPC correction on the initial target pattern to obtain a correction mask of the initial target pattern, and comparing the correction mask of the initial target pattern with the initial target pattern to obtain a deviation table;

[0008] A target pattern to be corrected is provided, wherein the target pattern to be corrected is the same as the initial target pattern, the deviation table is imported into an OPC formula, and OPC correction is performed on the target pattern to be corrected to obtain a correction mask of the target pattern to be corrected.

[0009] Optionally, the deviation table is classified based on different line width patterns in the initial target graphic.

[0010] Optionally, the deviation table corresponding to the same line width pattern includes line end deviations, empty end deviations, one-dimensional structure deviations and two-dimensional structure deviations corresponding to different spacings.

[0011] Optionally, the step of obtaining a correction mask of the initial target pattern includes:

[0012] Based on the initial target graphic, an OPC model is formed to perform simulation to obtain a simulation contour graphic, and the simulation contour graphic is compared with the initial target graphic to obtain an EPE value;

[0013] Determine whether the EPE value is within a preset range. If the EPE value is within the preset range, the mask plate corresponding to the simulated contour graphic is a corrected mask plate of the initial target graphic. If the EPE value is not within the preset range, move the edge of the mask plate, and simulate the moved mask plate to obtain a simulated contour graphic again, until the EPE value is within the preset range, and the corresponding mask plate is a corrected mask plate of the initial target graphic.

[0014] Optionally, the simulation contour graph is obtained based on light intensity distribution.

[0015] Optionally, the initial target graphic is in a GDS file format, and the target graphic to be corrected is in a GDS file format.

[0016] Optionally, after obtaining the correction mask of the target pattern to be corrected, the method further includes a step of optical proximity effect correction verification.

[0017] As described above, in the method of reducing the optical proximity effect correction time of the present invention, after the initial target graphic is subjected to OPC correction, a deviation table between the correction mask plate of the initial target graphic and the initial target graphic is obtained, and when the target graphic to be corrected of the same graphic is subsequently corrected, the deviation table is imported into the OPC formula for correction, thereby greatly reducing the OPC correction time and improving the OPC correction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a flow chart of a method for reducing optical proximity effect correction time in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0020] See also Figure 1 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0021] This embodiment provides a method for reducing the optical proximity effect correction time. Figure 1 , including the following steps:

[0022] S1: providing an initial target pattern, performing OPC correction on the initial target pattern to obtain a correction mask of the initial target pattern, and comparing the correction mask of the initial target pattern with the initial target pattern to obtain a deviation table;

[0023] S2: providing a target pattern to be corrected, wherein the type of the target pattern to be corrected is consistent with that of the initial target pattern, importing the deviation table into an OPC formula, performing OPC correction on the target pattern to be corrected, and obtaining a correction mask of the target pattern to be corrected.

[0024] As an example, the step of obtaining a modified mask of the initial target pattern includes:

[0025] (1) forming an OPC model based on the initial target pattern to perform simulation, obtaining a simulation contour pattern, and comparing the simulation contour pattern with the initial target pattern to obtain an EPE value;

[0026] (ii) determining whether the EPE value is within a preset range; if the EPE value is within the preset range, the mask plate (photomask) corresponding to the simulated contour graphic is a corrected mask plate of the initial target graphic; if the EPE value is not within the preset range, moving the edge of the mask plate, and simulating the moved mask plate to obtain a simulated contour graphic again, until the EPE value is within the preset range, and the corresponding mask plate is a corrected mask plate of the initial target graphic.

[0027] Specifically, the initial target graphic is imported into the OPC software, an OPC model is constructed for simulation to obtain a simulated contour graphic, and then the simulated contour graphic is compared with the line width (CD) of the initial target graphic to obtain the EPE value, at which time the EPE will be larger; then the edge of the mask is moved and then simulated again to change the EPE value; usually several repetitions are required to obtain a lower EPE, because the amount of each movement of the mask edge is limited, and it cannot be moved significantly at one time to avoid the risk of over-correction. Ideally, the EPE after correction is 0, but in actual operation it is unlikely to be corrected to 0, and it is sufficient to correct it to an EPE close to 0, and the corresponding mask is the corrected mask of the initial target graphic.

[0028] As an example, in this embodiment, the initial target graphic is in the GDS (Graphic Data System) file format, which is widely used in the storage and transmission of graphic data in semiconductor manufacturing processes. Of course, in other examples, the file format of the initial target graphic can be changed according to needs, and is not limited to this embodiment.

[0029] As an example, the simulated contour graphic is obtained based on the light intensity distribution. The smaller the EPE is, the closer the simulated contour graphic is to the target graphic, and the closer the corresponding mask is to the final corrected mask.

[0030] As an example, because different graphic features have different requirements for OPC correction, the more complex the graphic and the smaller the line width, the more likely it is that the diffracted light will interfere with each other, increasing the correction amount. The deviations in different areas are sorted and classified according to the pattern type, spacing and line width.

[0031] As an example, please refer to Table 1 and Table 2, which respectively show the deviation table corresponding to the line width of 60nm and the deviation table corresponding to the line width of 70nm, including the line end deviation, space end deviation, one-dimensional structure (1D) deviation and two-dimensional structure (2D) deviation corresponding to different line pitches. Specifically, in the deviation table corresponding to the same line width, for different line pitches, the deviations of the same category will have roughly the same trend as the line pitch increases. In the deviation table corresponding to the same line width, for the same line pitch, the deviations of different types are also inconsistent, such as the one-dimensional structure deviation is the smallest, the line end deviation is the largest, and the deviation of the small line width (60nm) figure is greater than the deviation of the large line width (70nm) figure.

[0032] Table 1:

[0033]

[0034] Table 2:

[0035]

[0036] It should be noted that Table 1 and Table 2 only list the deviation tables corresponding to 60nm line width and 70nm line width. In the actual target graphics, graphics of other line widths are also included. The deviation tables corresponding to other line widths are obtained according to the needs.

[0037] As an example, the target graphic to be corrected is the same as the initial target graphic. The deviation table obtained in step S1 is used to estimate the correction amount of the target graphic to be corrected. Before the OPC correction is performed on the graphic to be corrected, the deviation table obtained in step S1 is imported into an OPC recipe, and then the OPC correction is performed on the target graphic to be corrected. Since the OPC recipe imports the deviation table, when the OPC correction is performed, the starting mask plate is similar to the corrected mask plate, so that the starting EPE is smaller, so that the correction time (OPC run time) can be reduced during the correction, and the corrected mask plate of the target graphic to be corrected is obtained in a shorter correction time.

[0038] As an example, in this embodiment, the target graphic to be corrected is in the GDS file format. Of course, in other examples, the file format of the target graphic to be corrected can be changed according to needs, and is not limited to this embodiment.

[0039] As an example, after obtaining the correction mask plate of the target pattern to be corrected through OPC correction, it also includes the step of optical proximity effect correction verification, and simulating the photolithography process of the correction mask plate of the target pattern to be corrected, and obtaining the simulated contour pattern and comparing it with the target pattern to be corrected to confirm whether it meets the requirements; of course, it can also be verified by experiment, after making the correction mask plate, performing the photolithography process in the machine, and comparing the photolithography pattern with the target pattern to be corrected to confirm whether it meets the requirements.

[0040] As an example, in the prior art, for example, the number of correction iterations of the OPC correction of the initial target graphic is 10, and when OPC correction is required to be performed on the target graphic to be corrected with the same graphic subsequently, the number of correction iterations is also 10; and through the solution of the present application, for example, the number of correction iterations of the OPC correction of the initial target graphic is 10, and when OPC correction is required to be performed on the target graphic to be corrected with the same graphic subsequently, the number of correction iterations is 2 or 3 to obtain the required correction mask, thereby reducing the correction time.

[0041] As an example, this embodiment only exemplifies the number of correction iterations for illustration. In actual correction, different numbers of correction iterations will be generated according to the graphic type and technical node, and this embodiment is not intended to limit the number of correction iterations.

[0042] In summary, in the method of reducing the optical proximity effect correction time of the present invention, after the initial target pattern is corrected by OPC, a deviation table between the correction mask of the initial target pattern and the initial target pattern is obtained. When the target pattern to be corrected of the same pattern is subsequently corrected, the deviation table is imported into the OPC formula for correction, which greatly reduces the correction time and improves the OPC correction efficiency. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for reducing optical proximity effect correction time, characterized in that: The following steps are involved: Providing an initial target pattern, performing OPC correction on the initial target pattern to obtain a correction mask of the initial target pattern, and comparing the correction mask of the initial target pattern with the initial target pattern to obtain a deviation table; A target pattern to be corrected is provided, wherein the target pattern to be corrected is the same as the initial target pattern, the deviation table is imported into an OPC formula, and OPC correction is performed on the target pattern to be corrected to obtain a correction mask of the target pattern to be corrected.

2. The method for reducing optical proximity effect correction according to claim 1, characterized in that: The deviation table is classified based on different line width patterns in the initial target graphic.

3. The method for reducing optical proximity effect correction according to claim 2, characterized in that: The deviation table corresponding to the same line width pattern includes line end deviations, empty end deviations, one-dimensional structure deviations and two-dimensional structure deviations corresponding to different spacings.

4. The method for reducing optical proximity effect correction according to claim 1, wherein: The step of obtaining a correction mask of the initial target pattern comprises: Based on the initial target graphic, an OPC model is formed to perform simulation to obtain a simulation contour graphic, and the simulation contour graphic is compared with the initial target graphic to obtain an EPE value; Determine whether the EPE value is within a preset range. If the EPE value is within the preset range, the mask plate corresponding to the simulated contour graphic is a corrected mask plate of the initial target graphic. If the EPE value is not within the preset range, move the edge of the mask plate, and simulate the moved mask plate to obtain a simulated contour graphic again, until the EPE value is within the preset range, and the corresponding mask plate is a corrected mask plate of the initial target graphic.

5. The method for reducing optical proximity effect correction time according to claim 4, characterized in that: The simulation contour graph is obtained based on the light intensity distribution.

6. The method for reducing optical proximity effect correction time according to claim 1, characterized in that: The initial target graphic is in the GDS file format, and the target graphic to be corrected is in the GDS file format.

7. The method for reducing optical proximity effect correction time according to claim 1, characterized in that: After obtaining the correction mask of the target pattern to be corrected, the method further includes a step of optical proximity effect correction verification.

Images