Method for improving optical proximity correction line end convergence

Abstract

The application provides a method for improving optical proximity correction line end convergence, providing a target pattern, forming a to-be-corrected pattern at the contour edge of the target pattern, obtaining a first post-exposure contour according to the to-be-corrected pattern, and the first post-exposure contour has a first edge placement error with the target pattern; setting a first negative feedback coefficient and a first feedback value of each line segment according to the first edge placement error; introducing the first feedback coefficient and the first feedback value into an optical proximity correction program, moving the corresponding line segment by using the first feedback coefficient and the first feedback value, obtaining a second correction pattern, so that a second edge placement error of the second correction pattern is less than a set threshold; and iterating the second correction pattern by using the optical proximity correction program. The feedback value is set in the first step of the line end correction of the to-be-corrected ion implantation layout by the application, so that in the first step of the correction, the moving distance of the line segment is avoided to be too large, and the line end contour of the final correction pattern is as possible as to conform to the target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a method for improving line-end convergence of optical proximity correction. BACKGROUND

[0002] For the process of advanced technology node, the OPC corrects the design layout based on the lithography process model. The process of OPC correction for the layout is as follows: first, the edges of the layout pattern are cut into fragments (line segments), and then the fragments are divided into corner fragments (corner line segments) and center fragments (center line segments) according to whether the fragments contact the corners of the layout pattern.

[0003] In the case of ion implantation layout with large line-end convergence, the edge placement error (EPE) of part of the line end cannot be made to be zero or below 2nm, and the edge placement error of the line end will be affected by the adjacent corner fragment. Although the edge placement error of the line end moves in the direction of approaching zero in each iteration, the final result after all iterations will select the optimal solution for 1D (one-dimensional pattern) and 2D (two-dimensional pattern), which will cause the edge placement error of the like line end to be large.

[0004] To solve the above problems, a new method for improving line-end convergence of optical proximity correction is needed. SUMMARY

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a method for improving line-end convergence of optical proximity correction, which is used to solve the problem that in the prior art, in the case of large line-end convergence, the edge placement error (EPE) of part of the line end cannot be made to be zero or below 2nm, and the edge placement error of the line end will be affected by the adjacent corner fragment. Although the edge placement error of the line end moves in the direction of approaching zero in each iteration, the final result after all iterations will select the optimal solution for 1D and 2D, which will cause the edge placement error of the like line end to be large.

[0006] To achieve the above-mentioned purposes and other related purposes, the present application provides a method for improving line-end convergence of optical proximity correction, comprising:

[0007] Step one, providing a target pattern, forming a to-be-corrected pattern composed of a plurality of sequentially connected line segments on the contour edge of the target pattern, obtaining a first post-exposure contour according to the to-be-corrected pattern, the first post-exposure contour having a first edge placement error with the target pattern;

[0008] Step two, setting a first feedback coefficient and a first feedback value of each of the line segments according to the first edge placement error respectively;

[0009] Step three, importing the first feedback coefficient and the first feedback value into the optical proximity correction program, moving the corresponding line segments by using the first feedback coefficient and the first feedback value, obtaining a second correction pattern, so that a second edge placement error of the second correction pattern is less than a set threshold value;

[0010] Step four, iterating the second correction pattern by using the optical proximity correction program.

[0011] Preferably, the shape of the target pattern in step one is a rectangle.

[0012] Preferably, the target pattern in step one is an ion implantation layout.

[0013] Preferably, the length of each of the line segments in step one is equal.

[0014] Preferably, the length of each of the line segments in step one is 140 nanometers.

[0015] Preferably, the length of each of the line segments in step one is 100 nanometers.

[0016] Preferably, the negative feedback coefficient in step two is greater than or equal to 0 and less than or equal to 1.

[0017] Preferably, the method for moving the corresponding line segments according to the first feedback coefficient and the first feedback value in step three to obtain the second correction pattern is that: the distance Y1 moved by each of the line segments is A1+K1*X1, wherein A1 is the first feedback value, X1 is the first edge placement error, and K1 is the first feedback coefficient.

[0018] Preferably, the edge placement error of the final pattern after iteration of the second correction pattern in step four approaches 1 nanometer.

[0019] As described above, the method for improving the convergence of the line end of the optical proximity correction according to the present application has the following beneficial effects:

[0020] The present application sets a feedback value in the first step of the line end correction of the ion implantation layout to be corrected in advance, so that in the first step of correction, the movement distance of the line segment is avoided to be too large, and the line end profile of the final correction pattern is made to conform to the target as much as possible by combining with the appropriate line segment, negative feedback coefficient and iteration setting. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure shows the schematic diagram of the optical proximity correction method of the present application;

[0022] Figure 2 A schematic diagram showing the optical proximity correction parameter setting of the present application;

[0023] Figure 3 A schematic diagram showing the edge placement error after the first iteration of the target pattern of the present application;

[0024] Figure 4 A schematic diagram showing the result after the first iteration of the embodiment of the present application;

[0025] Figure 5 A schematic diagram showing the final exposure profile of the present application. DETAILED DESCRIPTION

[0026] The present application can be implemented or applied in other different embodiments, and the details in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0027] Referring to Figure 1 The present application provides a method for improving the line-end convergence of optical proximity correction, comprising:

[0028] Step one, providing a target pattern, forming a to-be-corrected pattern of a plurality of sequentially connected line segments (fragments) on the contour edge of the target pattern, the line segment (fragment) being the smallest moving unit in optical proximity correction, obtaining a first exposure profile according to the to-be-corrected pattern, the first exposure profile having a first edge placement error with the target pattern; in the prior art, the optical proximity correction program usually sets the line segment length (ajd fragment), the negative feedback coefficient (feedback), and the iteration setting (iteration movement) to correct the target pattern.

[0029] In the embodiment of the present application, the shape of the target pattern in step one is a rectangle.

[0030] In the embodiment of the present application, the target pattern in step one is an ion implantation layout, and the corner in the ion implantation layout is a corner fragment (corner line segment). In the case of large line-end convergence (line-end short) of the ion implantation layout, the edge placement error (epe) of part of the line end cannot be made to be zero or below 2 nm, and the edge placement error of the line end will be affected by the adjacent corner fragment.

[0031] In the embodiment of the present application, the length of each line segment in step one is equal.

[0032] In the embodiment of the present application, the length of each line segment in step one is 140 nanometers.

[0033] In the embodiment of the present application, the length of each line segment in step one is 100 nanometers.

[0034] Step two, setting the first feedback coefficient and the first feedback value of each line segment according to the first edge placement error, that is, the first feedback value is added in this step to avoid the line segment moving too far or too little in the first optical proximity correction, which leads to the edge placement error not reaching the target value in the subsequent iteration process.

[0035] In the embodiment of the present application, the negative feedback coefficient in step two is greater than or equal to 0 and less than or equal to 1.

[0036] Step three, importing the first feedback coefficient and the first feedback value in the optical proximity correction program, moving the corresponding line segment by using the first feedback coefficient and the first feedback value to obtain a second correction pattern, so that the second edge placement error of the second correction pattern is less than the set threshold, that is, the second correction pattern obtained after the line segment is moved in the first optical proximity correction has a reduced edge placement error between the profile after exposure and the original pattern.

[0037] In the embodiment of the present application, please refer to Figure 2 , the method for moving the corresponding line segment according to the first feedback coefficient and the first feedback value to obtain the second correction pattern in step three is: the distance Y1 moved by each line segment = A1 + K1 * X1, wherein A1 is the first feedback value, X1 is the first edge placement error, K1 is the first feedback coefficient, and K1 is usually set empirically. If the edge placement error at this position is large, the set value of A1 is increased. If the edge placement error at this position is small, the set value of A1 is decreased. By setting different parameters, a pattern as shown in Figure 3 can be obtained.

[0038] Step four, iterating the second correction pattern by using the optical proximity correction program.

[0039] In the embodiment of the present application, the edge placement error of the final pattern after the iteration of the second correction pattern in step four tends to be 1 nanometer.

[0040] In the embodiment of the present application, the length of the line segment of the control group is 140 nm, the negative feedback coefficient is 0.2, the first edge placement error at one side of the graph to be corrected is 30 nm, then the moving distance of the line segment at the side after the first iteration is 20+30*0.2=26 nm; the length of the line segment of the first experimental group is 100 nm, the negative feedback coefficient is 0.2, the first edge placement error at one side of the graph to be corrected is 30 nm, then the moving distance of the line segment at the side after the first iteration is 20+30*0.2=26 nm, the first iteration result is shown in Figure 4 , the simulated exposure profiles of the two are shown in Figure 5 , the epe of the line end approaches 1 nm, and the corner rounding is improved by 2.5 nm.

[0041] It should be noted that the diagrams provided in the embodiment only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, rather than the number, shape and size of the components when actually implemented. The type, number and proportion of the components when actually implemented can be arbitrarily changed, and the layout type of the components can be more complex.

[0042] In summary, the present application sets the feedback value in the first step of the correction of the line end of the ion implantation graph to be corrected in advance, so that the moving distance of the line segment is avoided to be too large in the first step of the correction, and the line end profile of the final corrected graph is made to conform to the target as much as possible by combining the appropriate line segment, negative feedback value and iteration setting. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0043] The above embodiment only exemplarily illustrates the principle and effect of the present application, and is not used to limit the present application. Any person skilled in the art can modify or change the above embodiment without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method of improving line end convergence of optical proximity correction, characterized by, At least comprising: Step one, providing a target pattern, forming a plurality of sequentially connected line segments on the contour edge of the target pattern to form a to-be-corrected pattern, obtaining a first exposure contour according to the to-be-corrected pattern, the first exposure contour has a first edge placement error X1 with the target pattern, the length of each line segment is equal, and the length of each line segment is 100 nanometers; Step two, setting a first negative feedback coefficient K1 and a first feedback value A1 of each line segment according to the first edge placement error X1; Step three, importing the first negative feedback coefficient K1 and the first feedback value A1 into an optical proximity correction program, moving the corresponding line segment by using the first negative feedback coefficient K1 and the first feedback value A1, and obtaining a second correction pattern, wherein the distance Y1 moved by each line segment is A1+K1*X1, so that the second edge placement error of the second correction pattern is less than a set threshold value; Step four, iteratively using the optical proximity correction program on the second correction pattern.

2. The method of improving line end convergence of optical proximity correction of claim 1, wherein: The shape of the target pattern in step one is a rectangle.

3. The method of improving line end convergence of optical proximity correction of claim 2, wherein: The target pattern in step one is an ion implantation layout.

4. The method of improving line end convergence of optical proximity correction of claim 1, wherein: The negative feedback coefficient in step two is greater than or equal to 0 and less than or equal to 1.

5. The method of improving line end convergence of optical proximity correction of claim 1, wherein: The edge placement error of the final pattern after iteration of the second correction pattern in step four approaches 1 nanometer.

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