Optical Proximity Correction Method

Abstract

An optical proximity correction method includes: providing a target pattern, the target pattern comprising several groups of similar edges; segmenting each group of similar edges to obtain several segments; adjusting the position parameters of the control points of each segment in each group of similar edges, as well as the radius parameters of each corner of the target pattern, to establish an original parameter matrix; performing optical proximity corrections on the target pattern several times based on the original parameter matrix, obtaining exposure patterns after each optical proximity correction, and obtaining an optimal exposure pattern from the exposure patterns; and obtaining an optimal parameter allocation in the original parameter matrix corresponding to the optimal exposure pattern. Obtaining the optimal exposure pattern while ensuring that the target pattern is not enlarged effectively avoids the risk of short circuits, increases the area of ​​the exposure pattern, and improves the reliability of subsequent processes.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to an optical proximity correction method. Background Art

[0002] Photolithography is a crucial technology in semiconductor manufacturing. It enables the transfer of patterns from a mask onto the surface of a silicon wafer, creating semiconductor products that meet design requirements. The photolithography process consists of an exposure step, a development step following the exposure step, and an etching step following the development step. During the exposure step, light passes through the light-transmitting areas of the mask onto a silicon wafer coated with photoresist, causing the photoresist to undergo a chemical reaction under the irradiation of light. During the development step, the different solubility of the developer in the photosensitive and unsensitive photoresists is exploited to form a photoresist pattern, enabling the transfer of the mask pattern to the photoresist. During the etching step, the silicon wafer is etched based on the photoresist pattern formed in the photoresist layer, further transferring the mask pattern to the wafer.

[0003] In semiconductor manufacturing, as design dimensions continue to shrink, approaching the limits of photolithography imaging systems, the diffraction effect of light becomes increasingly pronounced, ultimately leading to optical image degradation of the designed pattern. The actual photolithography pattern formed is severely distorted relative to the pattern on the mask, and the actual pattern formed by photolithography on the silicon wafer is ultimately different from the designed pattern. This phenomenon is called the Optical Proximity Effect (OPE).

[0004] Optical Proximity Correction (OPC) was developed to correct for the optical proximity effect. The core concept of OPC is to establish an OPC model based on the consideration of offsetting the optical proximity effect. The photomask pattern is designed based on the OPC model. This allows the photomask pattern to be closer to the target pattern desired by the user, even though the optical proximity effect may occur in the photolithography pattern relative to the mask pattern after photolithography. This offset has been taken into account when designing the photomask pattern based on the OPC model.

[0005] However, there are still many problems with optical proximity correction in the prior art. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide an optical proximity correction method to improve the effect of optical proximity correction.

[0007] To solve the above-mentioned problem, the technical solution of the present invention provides an optical proximity correction method, comprising: providing a target graphic, the target graphic comprising a plurality of groups of edges of the same type; segmenting each group of edges of the same type to obtain a plurality of segments; adjusting the position parameters of the control points of each segment in each group of edges of the same type, and the radius parameters of each corner of the target graphic, to establish an original parameter matrix; performing optical proximity corrections on the target graphic several times according to the original parameter matrix, obtaining an exposure graphic after each optical proximity correction, and obtaining an optimal exposure graphic from the plurality of exposure graphics; and obtaining an optimal parameter allocation in the original parameter matrix corresponding to the optimal exposure graphic.

[0008] Optionally, the target graphic includes: a rectangle.

[0009] Optionally, the target graph includes relatively distributed first edges of the same type and relatively distributed second edges of the same type, and the first edges of the same type and the second edges of the same type are vertically connected.

[0010] Optionally, each group of the same type of edges is segmented to obtain a number of segmented segments, including: dividing the first same type of edges into a first corner segment, a second corner segment, and a number of first intermediate segments, and the number of first intermediate segments are located between the first corner segment and the second corner segment; dividing the second same type of edges into a third corner segment, a fourth corner segment, and a number of second intermediate segments, and the number of second intermediate segments are located between the third corner segment and the fourth corner segment.

[0011] Optionally, the first corner segment, the second corner segment, the third corner segment and the fourth corner segment are equal.

[0012] Optionally, the position parameters of the control points of each segment in each group of the same type of edges include: the vertical distance between the control point and the corresponding segment, wherein when the control point is located inside the target graphic, the vertical distance is negative, and when the control point is located outside the target graphic, the vertical distance is positive; the parallel distance between the control point and the endpoint of the corresponding segment after being projected onto the corresponding segment, wherein, when the segment is a corner segment, the parallel distance is the distance between the control point and the corner endpoint of the corresponding segment after being projected onto the corresponding segment, and when the segment is an intermediate segment, the parallel distance is the distance between the control point and the endpoint of the corresponding segment closest to the corner point of the target graphic after being projected onto the corresponding segment.

[0013] Optionally, the vertical distance ranges from -10 nanometers to 10 nanometers.

[0014] Optionally, the adjustment step size of the vertical distance is 1 nanometer.

[0015] Optionally, the range of the parallel distance is: 0 times to 1 times the length of the corresponding segment.

[0016] Optionally, the adjustment step of the parallel distance is 0.1 times of the corresponding segment.

[0017] Optionally, the radius parameter of each corner of the target graphic ranges from 0 times to 1 times the length of the corresponding corner segment.

[0018] Optionally, the adjustment step of the radius parameter is 0.2 times the corresponding corner segment.

[0019] Optionally, the method of performing several optical proximity corrections on the target graphic according to the original parameter matrix includes: obtaining a simplified parameter matrix from the original parameter matrix, wherein the adjustment step size of each parameter in the simplified parameter matrix is ​​larger than the adjustment step size in the original parameter matrix; performing several first optical proximity corrections on the target graphic according to the simplified parameter matrix, confirming the correction trend of each parameter in the simplified parameter matrix for the first optical proximity correction, and obtaining a better parameter area for each parameter in the simplified parameter matrix; and performing several second optical proximity corrections on the target graphic by applying the original parameter matrix in the better parameter area.

[0020] Optionally, the method for obtaining an optimal exposure pattern from the plurality of exposure patterns includes: obtaining an exposure pattern having an area greater than a threshold area from the plurality of exposure patterns; obtaining placement edge errors between corresponding sampling points of each exposure pattern having an area greater than the threshold and the target pattern; and obtaining placement edge error ratio values ​​of each exposure pattern having an area greater than the threshold according to a root mean square (RMS) formula, wherein:

[0021]

[0022] Among them, EPE i is the placement edge error of each sampling point in the exposure pattern with an area greater than the threshold, W i is the weight of the placement edge error of each sampling point; and the exposure pattern corresponding to the minimum placement edge error ratio value is used as the optimal exposure pattern.

[0023] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0024] In the optical proximity correction method of the present invention, an original parameter matrix is ​​established by adjusting the position parameters of the control points of each segment in each group of the same type of edges, as well as the radius parameters of each corner of the target pattern. Based on the original parameter matrix, the target pattern is subjected to multiple optical proximity corrections, and an exposure pattern is obtained after each optical proximity correction. The optimal exposure pattern is then obtained from the multiple exposure patterns. This optimal exposure pattern is obtained without enlarging the target pattern, thereby effectively avoiding the risk of short circuits, increasing the area of ​​the exposure pattern, and enhancing the reliability of subsequent processes.

[0025] Furthermore, the method of performing multiple optical proximity corrections on the target pattern based on the original parameter matrix includes: obtaining a simplified parameter matrix from the original parameter matrix, wherein the adjustment step size of each parameter in the simplified parameter matrix is ​​larger than the adjustment step size in the original parameter matrix; performing multiple first optical proximity corrections on the target pattern based on the simplified parameter matrix, determining the correction trend of each parameter in the simplified parameter matrix with respect to the first optical proximity correction, and obtaining an optimal parameter region for each parameter in the simplified parameter matrix; and applying the original parameter matrix to the target pattern within the optimal parameter region. Because the original parameter matrix contains a large number of combinations, the optimal parameter region can be quickly obtained based on the correction trend of the simplified parameter matrix, thereby reducing workload and improving correction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of an optical proximity correction method according to an embodiment of the present invention;

[0027] Figures 2 to 5 1 is a schematic structural diagram of each step of the optical proximity correction method in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] As described in the background art, there are still many problems with optical proximity correction in the prior art, which will be described in detail below.

[0029] As process nodes decrease, the optical proximity effect will cause deformation and distortion of patterns on the wafer. The phenomena can be divided into the following categories: size difference between dense patterns and isolated patterns, nonlinear ratio between mask size and pattern size on the wafer, corner rounding, and line end shortening.

[0030] Taking corner rounding as an example, isolated, small-area graphics in the metal layer layout design may have corner rounding issues, which may result in a smaller area of ​​the final exposed graphic, thus introducing risks in the process. The traditional correction method is to expand the edges of the small, isolated graphics to ensure that the exposed graphic area increases after optical proximity correction. However, due to the different surrounding environments of the small, isolated graphics, especially in areas with dense lines, expanding the edges may reduce the process window for the spacing between some metal lines, thereby introducing short circuit risks.

[0031] Based on this, the present invention provides an optical proximity correction method. This method establishes an original parameter matrix by adjusting the position parameters of the control points of each segment within each group of edges of the same type, as well as the radius parameters of each corner of the target pattern. The method then performs multiple optical proximity corrections on the target pattern based on the original parameter matrix, obtaining exposure patterns after each optical proximity correction. The optimal exposure pattern is then obtained from the multiple exposure patterns. This optimal exposure pattern is obtained without enlarging the target pattern, effectively avoiding the risk of short circuits, increasing the area of ​​the exposure pattern, and enhancing the reliability of subsequent processes.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Figure 1 is a flow chart of an optical proximity correction method according to an embodiment of the present invention, comprising:

[0034] Step S101, providing a target graph, wherein the target graph includes a plurality of groups of edges of the same type;

[0035] Step S102, segmenting each group of edges of the same type to obtain a number of segmented segments;

[0036] Step S103, adjusting the position parameters of the control points of each segment in each group of the same type of edges and the radius parameters of each corner of the target graphic to establish an original parameter matrix;

[0037] Step S104, performing optical proximity correction on the target pattern several times according to the original parameter matrix, obtaining an exposure pattern after each optical proximity correction, and obtaining an optimal exposure pattern from the exposure patterns;

[0038] Step S105 , obtaining the optimal parameter distribution in the original parameter matrix corresponding to the optimal exposure pattern.

[0039] The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.

[0040] Figures 2 to 5 1 is a schematic structural diagram of each step of the optical proximity correction method in an embodiment of the present invention.

[0041] Please refer to Figure 2 , providing a target graph 100, wherein the target graph 100 includes several groups of edges of the same type.

[0042] It should be noted that, in this embodiment, the target pattern 100 is a pattern after exposure under ideal conditions. However, due to the existence of the optical proximity effect, the pattern after exposure cannot remain consistent with the target pattern 100 .

[0043] In this embodiment, the target graphic 100 is a rectangle.

[0044] In other embodiments, the target pattern may also be an “L”-shaped or “Z”-shaped pattern.

[0045] In this embodiment, the target graph 100 includes: relatively distributed first edges L1 of the same type, and relatively distributed second edges L2 of the same type, wherein the first edges L1 of the same type are vertically connected to the second edges L2 of the same type.

[0046] It should be noted that, in this embodiment, the purpose of dividing the target graphic 100 into several groups of edges of the same type is that, in the subsequent process of optical proximity correction, only the parameters of one edge of the same type need to be input in each group of edges of the same type, and there is no need to input the parameters of each edge of the same type.

[0047] Please refer to Figure 3 , segment each group of the same type of edges to obtain a number of segmented segments.

[0048] In this embodiment, each group of the same type of edges is segmented, and the method for obtaining several segmented segments includes: dividing the first same type edge L1 into a first corner segment SLC1, a second corner segment SLC2 and several first intermediate segments SLR1, and the several first intermediate segments SLR1 are located between the first corner segment SLC1 and the second corner segment SLC2; dividing the second same type edge L2 into a third corner segment SLC3, a fourth corner segment SLC4 and several second intermediate segments SLR2, and the several second intermediate segments SLR2 are located between the third corner segment SLC3 and the fourth corner segment SLC4.

[0049] In this embodiment, the number of the plurality of first intermediate sections is 2, and the number of the plurality of second intermediate sections is 1.

[0050] In this embodiment, the first corner segment SLC1 , the second corner segment SLC2 , the third corner segment SLC3 , and the fourth corner segment SLC4 are equal.

[0051] Please refer to Figure 4 , adjusting the position parameters of the control points of each segment in each group of the same type of edges and the radius parameters of each corner of the target graphic to establish an original parameter matrix.

[0052] In this embodiment, the position parameters of the control points of each segment in each group of the same type of edges include: a vertical distance between the control point and the corresponding segment, wherein when the control point is located inside the target graphic, the vertical distance is negative, and when the control point is located outside the target graphic, the vertical distance is positive; a parallel distance between the control point and the endpoint of the corresponding segment after being projected onto the corresponding segment, wherein, when the segment is a corner segment, the parallel distance is the distance between the control point and the corner endpoint of the corresponding segment after being projected onto the corresponding segment, and when the segment is an intermediate segment, the parallel distance is the distance between the control point and the endpoint of the corresponding segment closest to the corner point of the target graphic after being projected onto the corresponding segment.

[0053] In this embodiment, the position parameters of the control point of the first corner segment SLC1 include: the vertical distance SLC1_t between the control point and the first corner segment SLC1; and the distance SLC1_s between the control point and the corner endpoint of the first corner segment SLC1 after the control point is projected onto the first corner segment SLC1.

[0054] In this embodiment, the position parameters of the control point of the second corner segment SLC2 include: the vertical distance SLC2_t between the control point and the second corner segment SLC2; the distance SLC2_t between the control point and the corner endpoint of the second corner segment SLC2 after the control point is projected onto the second corner segment SLC2.

[0055] In this embodiment, the position parameters of the control point of the third corner segment SLC3 include: the vertical distance SLC3_t between the control point and the third corner segment SLC3; the distance SLC3_s between the control point and the corner endpoint of the third corner segment SLC3 after the control point is projected onto the third corner segment SLC3.

[0056] In this embodiment, the position parameters of the control point of the fourth corner segment SLC4 include: the vertical distance SLC4_t between the control point and the fourth corner segment SLC4; the distance SLC4_s between the control point and the corner endpoint of the fourth corner segment SLC4 after the control point is projected onto the fourth corner segment SLC4.

[0057] In this embodiment, the position parameters of the control point of the first middle segment SLR1 include: the vertical distance SLR1_t between the control point and the first middle segment SLR1; the distance SLR1_s between the control point and the endpoint of the first middle segment SLR1 closest to the corner point of the target graphic after the control point is projected onto the first middle segment SLR1.

[0058] In this embodiment, the position parameters of the control point of the second middle segment SLR2 include: the vertical distance SLR2_t between the control point and the second middle segment SLR2; the distance SLR2_s between the control point and the endpoint of the second middle segment SLR2 closest to the corner point of the target graphic after the control point is projected onto the second middle segment SLR2.

[0059] In this embodiment, the vertical distance ranges from -10 nanometers to 10 nanometers.

[0060] In this embodiment, the adjustment step length of the vertical distance is 1 nanometer.

[0061] In this embodiment, the parallel distance ranges from 0 to 1 times the length of the corresponding segment, that is, SLC1_s=0 to SLC1, SLC2_s=0 to SLC2, SLC3_s=0 to SLC3, SLC4_s=0 to SLC4, SLR1_s=0 to SLR1, and SLR2_s=0 to SLR2.

[0062] In this embodiment, the adjustment step of the parallel distance is 0.1 times of the corresponding segment.

[0063] In this embodiment, the radius parameter of each corner of the target graphic ranges from 0 times to 1 times the length of the corresponding corner segment.

[0064] In this embodiment, the target graphic has four corners, and the radius parameters of the four corners are R1, R2, R3, and R4, respectively, wherein R1=0~SLC1, R2=0~SLC2, R3=0~SLC3, and R4=0~SLC4.

[0065] In this embodiment, the adjustment step of the radius parameter is 0.2 times the corresponding corner segment.

[0066] Please refer to Figure 5, performing optical proximity corrections on the target pattern 100 several times according to the original parameter matrix, obtaining an exposure pattern after each optical proximity correction, and obtaining an optimal exposure pattern 101 from the several exposure patterns.

[0067] In this embodiment, the method for performing multiple optical proximity corrections on the target pattern 100 based on the original parameter matrix includes: obtaining a simplified parameter matrix from the original parameter matrix, wherein the adjustment step size of each parameter in the simplified parameter matrix is ​​larger than the adjustment step size in the original parameter matrix; performing multiple first optical proximity corrections on the target pattern 100 based on the simplified parameter matrix, determining the correction trend of each parameter in the simplified parameter matrix with respect to the first optical proximity correction, and obtaining an optimal parameter region for each parameter in the simplified parameter matrix; and applying the original parameter matrix to the target pattern within the optimal parameter region. Because the original parameter matrix contains a large number of combinations, the optimal parameter region can be quickly obtained based on the correction trend of the simplified parameter matrix, thereby reducing workload and improving correction efficiency.

[0068] In this embodiment, the method for obtaining the optimal exposure pattern 101 from the plurality of exposure patterns includes: obtaining an exposure pattern having an area greater than a threshold area from the plurality of exposure patterns; obtaining placement edge errors between corresponding sampling points between each exposure pattern having an area greater than the threshold and the target pattern 100; and obtaining placement edge error ratio values ​​for each exposure pattern having an area greater than the threshold according to a root mean square (RMS) formula, wherein:

[0069]

[0070] Among them, EPE i is the placement edge error of each sampling point in the exposure pattern with an area greater than the threshold, W i is the weight of the placement edge error of each sampling point; and the exposure pattern corresponding to the minimum placement edge error ratio value is used as the optimal exposure pattern 101.

[0071] In this embodiment, an original parameter matrix is ​​established by adjusting the position parameters of the control points of each segment in each group of the same-type edges, as well as the radius parameters of each corner of the target pattern 100. Based on the original parameter matrix, several optical proximity corrections are then performed on the target pattern 100, and exposure patterns after each optical proximity correction are obtained. An optimal exposure pattern 101 is then obtained from the multiple exposure patterns. This optimal exposure pattern 101 is obtained without enlarging the target pattern 100, thereby effectively avoiding the risk of short circuits, increasing the area of ​​the exposure pattern, and enhancing the reliability of subsequent processes.

[0072] Please continue to refer to Figure 5 , obtaining the optimal parameter allocation in the original parameter matrix corresponding to the optimal exposure pattern 101.

[0073] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. An optical proximity correction method, characterized in that: include: providing a target graph, wherein the target graph includes a plurality of groups of edges of the same type; Segment each group of edges of the same type to obtain a number of segmented segments; Adjusting the position parameters of the control points of each segment in each group of the same type of edges and the radius parameters of each corner of the target graphic to establish an original parameter matrix; performing optical proximity corrections on the target pattern several times according to the original parameter matrix, obtaining an exposure pattern after each optical proximity correction, and obtaining an optimal exposure pattern from the exposure patterns; Obtaining optimal parameter allocation in the original parameter matrix corresponding to the optimal exposure pattern.

2. The optical proximity correction method according to claim 1, wherein: The target graphic includes: a rectangle.

3. The optical proximity correction method according to claim 2, wherein: The target graph includes relatively distributed first edges of the same type and relatively distributed second edges of the same type, wherein the first edges of the same type and the second edges of the same type are vertically connected.

4. The optical proximity correction method according to claim 3, wherein: The method of segmenting each group of the same type of edges to obtain a plurality of segmented segments includes: dividing the first same type of edges into a first corner segment, a second corner segment, and a plurality of first intermediate segments, wherein the plurality of first intermediate segments are located between the first corner segment and the second corner segment; dividing the second same type of edges into a third corner segment, a fourth corner segment, and a plurality of second intermediate segments, wherein the plurality of second intermediate segments are located between the third corner segment and the fourth corner segment.

5. The optical proximity correction method according to claim 4, wherein: The first corner segment, the second corner segment, the third corner segment, and the fourth corner segment are equal.

6. The optical proximity correction method according to claim 4, wherein: The position parameters of the control points of each segment in each group of the same type of edges include: a vertical distance between the control point and the corresponding segment, wherein when the control point is located inside the target graphic, the vertical distance is negative, and when the control point is located outside the target graphic, the vertical distance is positive; a parallel distance between the control point and the endpoint of the corresponding segment after being projected onto the corresponding segment, wherein, when the segment is a corner segment, the parallel distance is the distance between the control point and the corner endpoint of the corresponding segment after being projected onto the corresponding segment, and when the segment is an intermediate segment, the parallel distance is the distance between the control point and the endpoint of the corresponding segment closest to the corner point of the target graphic after being projected onto the corresponding segment.

7. The optical proximity correction method according to claim 6, wherein: The vertical distance ranges from -10 nanometers to 10 nanometers.

8. The optical proximity correction method according to claim 7, wherein: The adjustment step size of the vertical distance is 1 nanometer.

9. The optical proximity correction method according to claim 6, wherein: The range of the parallel distance is: 0 times to 1 times the length of the corresponding segment.

10. The optical proximity correction method according to claim 9, wherein: The adjustment step of the parallel distance is 0.1 times of the corresponding segment.

11. The optical proximity correction method according to claim 4, wherein: The range of the radius parameter of each corner of the target graphic is: 0 times to 1 times the length of the corresponding corner segment.

12. The optical proximity correction method according to claim 11, wherein: The adjustment step of the radius parameter is 0.2 times the corresponding corner segment.

13. The optical proximity correction method according to claim 1, wherein: The method for performing a plurality of optical proximity corrections on the target pattern according to the original parameter matrix includes: obtaining a simplified parameter matrix from the original parameter matrix, wherein an adjustment step size of each parameter in the simplified parameter matrix is ​​greater than an adjustment step size in the original parameter matrix; performing a plurality of first optical proximity corrections on the target pattern according to the simplified parameter matrix, confirming a correction trend of each parameter in the simplified parameter matrix with respect to the first optical proximity correction, and obtaining a preferred parameter region for each parameter in the simplified parameter matrix; and performing a plurality of second optical proximity corrections on the target pattern by applying the original parameter matrix in the preferred parameter region.

14. The optical proximity correction method according to claim 13, wherein: The method for obtaining an optimal exposure pattern from a plurality of exposure patterns includes: obtaining an exposure pattern having an area greater than a threshold area from the plurality of exposure patterns; obtaining placement edge errors between corresponding sampling points between each exposure pattern having an area greater than the threshold and a target pattern; and obtaining placement edge error ratio values ​​for each exposure pattern having an area greater than the threshold according to a root mean square (RMS) formula, wherein: Among them, EPE i is the placement edge error of each sampling point in the exposure pattern with an area greater than the threshold, W i is the weight of the placement edge error of each sampling point; and the exposure pattern corresponding to the minimum placement edge error ratio value is used as the optimal exposure pattern.

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