Optical proximity correction method

Abstract

An optical proximity correction method, comprising: providing a correction layout including a plurality of correction patterns; obtaining an exposure layout including a plurality of first exposure patterns according to the correction layout; obtaining a plurality of sampling points on the outline of the first exposure patterns in sequence by a plurality of sampling steps to form a sampling pattern, the i-th sampling step comprising: obtaining an i-th sampling point on the outline of the first exposure pattern; obtaining an L-th position point on the correction pattern corresponding to the first exposure pattern, the L-th position point corresponding to the i-th sampling point; obtaining a curvature of the i-th sampling point; obtaining a first offset between the i-th sampling point and the L-th position point; obtaining a second offset of the correction pattern between an L-1-th position point and the L-th position point, the L-1-th position point corresponding to an i-1-th sampling point; obtaining an i+1-th sampling step length according to the curvature of the i-th sampling point, the first offset and the second offset; and obtaining an i+1-th sampling point on the first exposure pattern according to the i+1-th sampling step length. The method improves the prediction accuracy.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more particularly to an optical proximity correction method. Background Technology

[0002] To transfer a pattern from a photomask to the surface of a silicon wafer, the process typically involves an exposure step, a development step following the exposure step, and an etching step following the development step. In the exposure step, light passes through the light-transmitting areas of the photomask and shines onto the silicon wafer coated with photoresist, causing a chemical reaction in the photoresist. In the development step, the different solubility of the developer in the photoresist and the non-photoresist is utilized to form a photolithographic pattern, transferring the photomask pattern onto the photoresist. In the etching step, the silicon wafer is etched based on the photolithographic pattern formed by the photoresist layer, further transferring the photomask pattern onto the silicon wafer.

[0003] In semiconductor manufacturing, as design dimensions continue to shrink and approach the limits of photolithography imaging systems, the diffraction effect of light becomes increasingly pronounced, leading to optical image degradation of the final design pattern. The actual photolithographic pattern formed is severely distorted relative to the pattern on the mask, resulting in a difference between the actual pattern formed on the silicon wafer and the design pattern. This phenomenon is called the Optical Proximity Effect (OPE).

[0004] To correct the optical proximity effect, Optical Proximity Correction (OPC) was developed. The core idea of ​​OPC is to establish an OPC model based on the consideration of counteracting the optical proximity effect. The photomask pattern is designed according to the OPC model. In this way, although the lithographic pattern and the corresponding photomask pattern have an optical proximity effect, the cancellation of this phenomenon has been considered when designing the photomask pattern according to the OPC model. Therefore, the lithographic pattern after photolithography is close to the target pattern actually desired by the user.

[0005] However, the prediction accuracy of existing optical proximity correction models still needs to be improved. Summary of the Invention

[0006] The technical problem solved by this invention is to provide an optical proximity correction method to improve the prediction accuracy of existing optical proximity correction models.

[0007] To solve the above technical problems, the present invention provides an optical proximity correction method, comprising: providing a correction pattern, the correction pattern including a plurality of correction patterns extending along a first direction; obtaining an exposure pattern based on the correction pattern, the exposure pattern including a plurality of first exposure patterns corresponding to the correction patterns; and acquiring a plurality of sampling points on the contour of the first exposure patterns in a plurality of sampling steps to form a sampling pattern, wherein adjacent sampling points are separated by segments, the i-th sampling step comprising: acquiring the i-th sampling point on the contour of the first exposure pattern; and in the... The Lth position point is obtained on the correction pattern corresponding to the first exposure pattern, and the Lth position point corresponds to the i-th sampling point; the curvature of the i-th sampling point is obtained; the first offset between the i-th sampling point and the Lth position point is obtained; the second offset of the contour line of the correction pattern between the (L-1)th position point and the Lth position point is obtained, and the (L-1)th position point corresponds to the (i-1)th sampling point on the first exposure pattern is obtained; the (i+1)th sampling step size is obtained according to the curvature of the i-th sampling point, the first offset, and the second offset; the (i+1)th sampling point is obtained on the contour of the first exposure pattern according to the (i+1)th sampling step size.

[0008] Optionally, the method for obtaining the (i+1)th sampling step size based on the curvature of the i-th sampling point, the first offset, and the second offset includes: obtaining a first weight, a second weight, and a third weight; and obtaining the sampling step size based on the first weight, the second weight, the third weight, the curvature of the i-th sampling point, the first offset, and the second offset. ,in, Let be the first offset between the i-th sampling point and the L-th position point. To correct the second offset of the outline of the graphic between the (L-1)th position point and the Lth position point, Let be the curvature of the i-th sampling point. The minimum size for the graphic design rules is defined by N, which is an adjustable variable, and i is a natural number greater than 0. The value of L is the same as the value of i. As the first weight, As the second weight, It is the third weight.

[0009] Optionally, the method for obtaining the first weight includes: obtaining the maximum size Mmax of the corrected shape in the second direction, where the second direction is perpendicular to the first direction; obtaining the minimum size Mmin of the corrected shape in the second direction; and obtaining the first weight based on the maximum size Mmax and the minimum size Mmin. .

[0010] Optionally, the method for obtaining the third weight includes: obtaining the third weight w3=0.2w1 based on the first weight.

[0011] Optionally, the method for obtaining the second weight includes: obtaining the maximum curvature Curve of the first exposure graphic outline in the exposure map. max According to the maximum curvature Cur... max Obtain the second weight .

[0012] Optionally, the method for obtaining the curvature of the i-th sampling point includes: when i=0, the sampling point is the starting sampling point, and the curvature of the starting sampling point is 0; when i=1, the curvature of the first sampling point is the curvature of the segment between the first sampling point and the starting sampling point; when i=2, the curvature of the second sampling point is the curvature of the segment between the second sampling point and the first sampling point.

[0013] Optionally, the method for obtaining the second offset of the contour line of the corrected graphic between the (L-1)th position point and the Lth position point includes: when i=0, the second offset is 0; when i=1, the second offset is the offset of the contour line of the corrected graphic between the starting position point and the first position point; when i=2, the second offset is the offset of the contour line of the corrected graphic between the first position point and the second position point, wherein the starting position point corresponds to the starting sampling point, the first position point corresponds to the first sampling point, and the second position point corresponds to the second sampling point.

[0014] Optionally, the method for obtaining the first offset between the i-th sampling point and the L-th position point includes: when i=0, the first offset is the offset between the starting sampling point and the starting position point; when i=1, the first offset is the offset between the first sampling point and the first position point; when i=2, the first offset is the offset between the second sampling point and the second position point.

[0015] Optionally, it also includes: correcting edge placement errors in the sampled pattern.

[0016] Optionally, the method for obtaining the adjustable variable N includes: setting N to a value of 1, and using several sampling steps to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern, wherein there are segmentation segments between adjacent sampling points; determining the number of segmentation segments; if the number of segmentation segments is greater than a preset value, then decreasing the value of N to make the value of N less than 1; if the number of segmentation segments is less than a preset value, then increasing the value of N to make the value of N greater than 1; and using several sampling steps again to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern according to the value of N, until the number of segmentation segments meets the preset value range.

[0017] Optionally, if the number of line segments in the segmented section meets the range of a preset value, then N is set to 1.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0019] The technical solution of this invention obtains the (i+1)th sampling step size based on the curvature of the i-th sampling point, the first offset, and the second offset, and then obtains the (i+1)th sampling point on the contour of the first exposure pattern based on the (i+1)th sampling step size. This improves the prediction accuracy of the optical proximity correction method. Attached Figure Description

[0020] Figure 1 and Figure 2 This is a flowchart illustrating an optical proximity correction method according to an embodiment of the present invention;

[0021] Figures 3 to 5 This is a schematic diagram of the optical proximity correction process in an embodiment of the present invention. Detailed Implementation

[0022] As described in the background section, the prediction accuracy of existing optical proximity models still needs to be improved.

[0023] Specifically, in current optical proximity correction models, there are typically two methods for sampling the contour of the simulated exposure pattern: one is to sample the contour at a uniform interval, and the other is to sample the contour at a random interval. Neither of these sampling methods allows the optical proximity correction model to obtain sufficiently accurate prediction results.

[0024] This invention provides an optical proximity correction method. The method obtains the (i+1)th sampling step size based on the curvature of the i-th sampling point, a first offset, and a second offset. Then, it obtains the (i+1)th sampling point on the contour of the first exposure pattern based on the (i+1)th sampling step size. This improves the prediction accuracy of the optical proximity correction method.

[0025] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Figure 1 and Figure 2 This is a flowchart illustrating an optical proximity correction method according to an embodiment of the present invention.

[0027] Please refer to Figure 1 and Figure 2 The optical proximity correction method includes:

[0028] Step S10: Provide a revised layout, the revised layout including a plurality of revised graphics, the revised graphics extending along a first direction;

[0029] Step S20: Obtain an exposure pattern based on the corrected pattern, wherein the exposure pattern includes a plurality of first exposure patterns corresponding to the corrected pattern;

[0030] Step S30: Several sampling steps are performed to obtain several sampling points on the outline of the first exposed pattern to form a sampling pattern. Adjacent sampling points are divided into segments. The i-th sampling step includes:

[0031] Step S301: Obtain the i-th sampling point on the outline of the first exposure pattern;

[0032] Step S302: Obtain the Lth position point on the correction pattern corresponding to the first exposure pattern, wherein the Lth position point corresponds to the i-th sampling point;

[0033] Step S303: Obtain the curvature of the i-th sampling point;

[0034] Step S304: Obtain the first offset between the i-th sampling point and the L-th position point;

[0035] Step S305: Obtain the second offset of the contour line of the correction pattern between the L-1 position point and the L position point, wherein the L-1 position point corresponds to the i-1 sampling point on the first exposure pattern;

[0036] Step S306: Obtain the (i+1)th sampling step size based on the curvature of the i-th sampling point, the first offset, and the second offset;

[0037] Step S307: Obtain the (i+1)th sampling point on the contour of the first exposure pattern according to the (i+1)th sampling step size.

[0038] The optical proximity correction method obtains the (i+1)th sampling step size based on the curvature of the i-th sampling point, a first offset, and a second offset, and then obtains the (i+1)th sampling point on the contour of the first exposure pattern based on the (i+1)th sampling step size. This improves the prediction accuracy of the optical proximity correction method.

[0039] Next, each step will be analyzed and explained.

[0040] Please continue to refer to this. Figure 1 Step S10: Provide a revised layout, the revised layout including a plurality of revised graphics, the revised graphics extending along a first direction.

[0041] The corrected pattern is a pattern that has undergone optical proximity correction, and can be a corrected photomask pattern.

[0042] Figure 3A modified layout 100 is provided as a schematic diagram of the modified layout. The modified layout 100 includes a plurality of modified graphics 101, which extend along a first direction X.

[0043] Please continue to refer to this. Figure 1 Step S20: Obtain an exposure pattern based on the corrected pattern, wherein the exposure pattern includes several first exposure patterns corresponding to the corrected pattern.

[0044] The exposure map can be an actual exposure map or a simulated exposure map.

[0045] Figure 4 This is a schematic diagram of the exposure pattern. An exposure pattern 200 is obtained based on the modified pattern 100. The exposure pattern 200 includes a plurality of first exposure patterns 201 corresponding to the modified pattern 101.

[0046] Please continue to refer to this. Figure 1 and Figure 2 Step S30: Several sampling steps are performed to obtain several sampling points on the outline of the first exposed pattern to form a sampling pattern. Adjacent sampling points are divided into segments. The i-th sampling step includes:

[0047] Step S301: Obtain the i-th sampling point on the outline of the first exposure pattern;

[0048] Step S302: Obtain the Lth position point on the correction pattern corresponding to the first exposure pattern, wherein the Lth position point corresponds to the i-th sampling point;

[0049] Step S303: Obtain the curvature of the i-th sampling point;

[0050] Step S304: Obtain the first offset between the i-th sampling point and the L-th position point;

[0051] Step S305: Obtain the second offset of the contour line of the correction pattern between the L-1 position point and the L position point, wherein the L-1 position point corresponds to the i-1 sampling point on the first exposure pattern;

[0052] Step S306: Obtain the (i+1)th sampling step size based on the curvature of the i-th sampling point, the first offset, and the second offset;

[0053] Step S307: Obtain the (i+1)th sampling point on the contour of the first exposure pattern according to the (i+1)th sampling step size.

[0054] Figure 5 For a schematic diagram of the sampling pattern 202, please refer to... Figure 5A number of sampling steps are performed to obtain a number of sampling points on the outline of the first exposure pattern 201 to form a sampling pattern 202, wherein adjacent sampling points are segmented. The i-th sampling step includes:

[0055] Please continue to refer to this. Figure 2 and Figure 5 Step S301: Obtain the i-th sampling point Site i on the outline of the first exposure pattern 201.

[0056] i is a natural number greater than 0, such as Figure 5 As shown, Site 0 is the starting sampling point.

[0057] In this embodiment, the starting sampling point is located on the central axis of the first exposure pattern 201.

[0058] Please continue to refer to this. Figure 2 and Figure 5 Step S302: Obtain the Lth position point on the correction pattern 101 corresponding to the first exposure pattern 201, wherein the Lth position point corresponds to the i-th sampling point.

[0059] Please continue to refer to this. Figure 2 and Figure 5 Execute step S303: Obtain the curvature of the i-th sampling point. .

[0060] The curvature of the i-th sampling point Let be the curvature of the segment between the i-th sampling point and the (i-1)-th sampling point.

[0061] Obtain the curvature of the i-th sampling point The method includes: when i=0, the curvature of the starting sampling point Site 0 is 0; when i=1, the curvature of the first sampling point Site1 is the curvature of the segment between the first sampling point Site 1 and the starting sampling point Site 0; when i=2, the curvature of the second sampling point Site2 is the curvature of the segment between the second sampling point Site 2 and the first sampling point Site1.

[0062] Please continue to refer to this. Figure 2 and Figure 5 Execute step S304: Obtain the first offset between the i-th sampling point and the L-th position point. .

[0063] First offset It represents the offset between the i-th sampling point and the L-th position point.

[0064] Obtain the first offset between the i-th sampling point and the L-th position point. The methods include:

[0065] When i=0, the first offset Δp0 is the offset between the starting sampling point Site 0 and the starting position point 0. The starting sampling point Site 0 and the starting position point 0 correspond to each other.

[0066] When i=1, the first offset Δp1 is the offset between the first sampling point Site 1 and the first position point 1; the first position point 1 corresponds to the first sampling point Site 1.

[0067] When i=2, the first offset Δp2 is the offset between the second sampling point Site 2 and the second position point 2, and the second position point 2 corresponds to the second sampling point Site 2.

[0068] Please continue to refer to this. Figure 2 and Figure 5 Step S305: Obtain the second offset of the contour line of the corrected graphic 101 between the (L-1)th position point and the Lth position point. The L-1 position point corresponds to the i-1 sampling point on the first exposure pattern 201.

[0069] The method for obtaining the second offset of the contour line of the corrected graphic 101 between the (L-1)th position point and the Lth position point includes: when i=0, the second offset ΔM0 is 0; when i=1, the second offset ΔM1 is the offset of the contour line of the corrected graphic 101 between the starting position point 0 and the first position point 1; when i=2, the second offset ΔM2 is the offset of the contour line of the corrected graphic 101 between the first position point 1 and the second position point 2.

[0070] Please continue to refer to this. Figure 2 and Figure 5 Execute step S306: Based on the curvature of the i-th sampling point First offset Second offset Obtain the (i+1)th sampling step size, Space i+1.

[0071] In this embodiment, based on the curvature of the i-th sampling point First offset Second offset The method for obtaining the (i+1)th sampling step size Space i+1 includes: obtaining the first weight, the second weight, and the third weight; and obtaining the (i+1)th sampling step size Space i+1 based on the first weight, the second weight, the third weight, the curvature of the i-th sampling point, the first offset, and the second offset. ,in, Let be the first offset between the i-th sampling point and the L-th position point. To correct the second offset of the outline of the graphic between the (L-1)th position point and the Lth position point, Let be the curvature of the i-th sampling point. The minimum size for the graphic design rules is defined by N, which is an adjustable variable, and i is a natural number greater than 0. The value of L is the same as the value of i. As the first weight, As the second weight, It is the third weight.

[0072] In this embodiment, the first weight is obtained. The method includes: obtaining the maximum size Mmax of the corrected shape 101 in the second direction Y, where the second direction Y is perpendicular to the first direction X; obtaining the minimum size Mmin of the corrected shape 101 in the second direction Y; and obtaining a first weight based on the maximum size Mmax and the minimum size Mmin. .

[0073] In this embodiment, the third weight is obtained. The methods include: based on the first weight Obtain the third weight w3 = 0.2w1.

[0074] In this embodiment, the second weight is obtained. The method includes: obtaining the maximum curvature Curve of the outline of the first exposure pattern 201 in the exposure pattern 200. max According to the maximum curvature Cur... max Obtain the second weight .

[0075] Please continue to refer to this. Figure 2 and Figure 5 Step S307: Obtain the (i+1)th sampling point Site i+1 on the contour of the first exposure pattern 201 according to the (i+1)th sampling step Space i+1.

[0076] In this embodiment, the method further includes: obtaining the adjustable variable N.

[0077] The method for obtaining the adjustable variable N includes: setting N to a value of 1, and using several sampling steps to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern, wherein there are segmentation segments between adjacent sampling points; determining the number of segmentation segments; if the number of segmentation segments is greater than a preset value, then decreasing the value of N to make the value of N less than 1; if the number of segmentation segments is less than a preset value, then increasing the value of N to make the value of N greater than 1; and using several sampling steps again to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern according to the value of N, until the number of segmentation segments meets the preset value range.

[0078] If the number of line segments in the segmentation meets the preset value range, then N is 1.

[0079] Please continue to refer to this. Figure 1 It also includes: correcting edge placement errors in the sampled pattern.

[0080] The accuracy of the edge placement error correction is improved.

[0081] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An optical proximity correction method, characterized in that, include: A revised layout is provided, the revised layout comprising a plurality of revised graphics, the revised graphics extending along a first direction; An exposure pattern is obtained based on the corrected pattern, wherein the exposure pattern includes a plurality of first exposure patterns corresponding to the corrected pattern; A number of sampling points are sequentially acquired on the outline of the first exposed pattern through several sampling steps to form a sampling pattern. Adjacent sampling points are separated by segments. The i-th sampling step includes: Obtain the i-th sampling point on the outline of the first exposed pattern; The Lth position point is obtained on the correction pattern corresponding to the first exposure pattern, and the Lth position point corresponds to the i-th sampling point; Obtain the curvature of the i-th sampling point; Obtain the first offset between the i-th sampling point and the L-th position point; Obtain the second offset of the contour line of the correction pattern between the (L-1)th position point and the Lth position point, where the (L-1)th position point corresponds to the (i-1)th sampling point on the first exposure pattern; The sampling step size is obtained based on the curvature of the i-th sampling point, the first offset, and the second offset, including: obtaining the first weight, the second weight, and the third weight; and obtaining the sampling step size based on the first weight, the second weight, the third weight, the curvature of the i-th sampling point, the first offset, and the second offset. ,in, Let be the first offset between the i-th sampling point and the L-th position point. To correct the second offset of the outline of the graphic between the (L-1)th position point and the Lth position point, Let be the curvature of the i-th sampling point. The minimum size for the graphic design rules is defined by N, which is an adjustable variable, and i is a natural number greater than 0. The value of L is the same as the value of i. As the first weight, As the second weight, As the third weight, First weight Where Mmax is the maximum size of the corrected shape in the second direction, which is perpendicular to the first direction; Mmin is the minimum size of the corrected shape in the second direction; and the third weight w3 = 0.2w1. Second weight Where Curmax is the maximum curvature of the first exposure pattern outline in the exposure pattern; The (i+1)th sampling point is obtained on the contour of the first exposure pattern according to the (i+1)th sampling step size.

2. The optical proximity correction method as described in claim 1, characterized in that, The method for obtaining the curvature of the i-th sampling point includes: when i=0, the sampling point is the starting sampling point, and the curvature of the starting sampling point is 0; when i=1, the curvature of the first sampling point is the curvature of the segment between the first sampling point and the starting sampling point; when i=2, the curvature of the second sampling point is the curvature of the segment between the second sampling point and the first sampling point.

3. The optical proximity correction method as described in claim 1, characterized in that, The method for obtaining the second offset of the contour line of the corrected graphic between the (L-1)th position point and the Lth position point includes: when i=0, the second offset is 0; when i=1, the second offset is the offset of the contour line of the corrected graphic between the starting position point and the first position point; when i=2, the second offset is the offset of the contour line of the corrected graphic between the first position point and the second position point, wherein the starting position point corresponds to the starting sampling point, the first position point corresponds to the first sampling point, and the second position point corresponds to the second sampling point.

4. The optical proximity correction method as described in claim 1, characterized in that, The method for obtaining the first offset between the i-th sampling point and the L-th position point includes: when i=0, the first offset is the offset between the starting sampling point and the starting position point; when i=1, the first offset is the offset between the first sampling point and the first position point; when i=2, the first offset is the offset between the second sampling point and the second position point.

5. The optical proximity correction method as described in claim 1, characterized in that, Also includes: Edge placement error correction is performed on the sampled image.

6. The optical proximity correction method as described in claim 1, characterized in that, The method for obtaining the adjustable variable N includes: setting N to a value of 1, and using several sampling steps to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern, wherein there are segmentation segments between adjacent sampling points; determining the number of segmentation segments; if the number of segmentation segments is greater than a preset value, increasing the value of N to make the value of N less than 1; if the number of segmentation segments is less than a preset value, decreasing the value of N to make the value of N greater than 1; and using several sampling steps again to obtain several sampling points on the contour of the first exposed pattern to form a sampling pattern according to the value of N, until the number of segmentation segments meets the preset value range.

7. The optical proximity correction method as described in claim 6, characterized in that, If the number of line segments in the segmentation meets the preset value range, then N is 1.

Images