An optical proximity correction method

Abstract

This application provides an optical proximity correction method, the method comprising: providing a target pattern, the target pattern comprising a plurality of first sub-patterns arranged in an array, each first sub-pattern comprising a rectangle, the rectangle comprising a short side along the horizontal direction and a long side along the vertical direction; obtaining a virtual pattern based on the target pattern, moving both long sides of each first sub-pattern inward by a distance ΔV and moving both short sides of each first sub-pattern outward by a distance ΔH to obtain a plurality of second sub-patterns, the plurality of second sub-patterns being the virtual pattern; and performing optical proximity correction based on the virtual pattern to obtain a photomask pattern. This application provides an optical proximity correction method that obtains a corresponding virtual pattern based on a target pattern, and subsequently performs optical proximity correction based on the virtual pattern to obtain a photomask pattern, which can still guarantee the accuracy of optical proximity correction at nodes of 10nm and below.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to an optical proximity correction method. Background Technology

[0002] In semiconductor manufacturing, as design dimensions continue to shrink, the diffraction effect of light becomes increasingly pronounced. As a result, the optical image of the design pattern is degraded, and the actual pattern formed on the substrate by photolithography eventually differs from the design pattern. This phenomenon is known as the Optical Proximity Effect (OPE).

[0003] To correct the optical proximity effect, Optical Proximity Correction (OPC) was developed. The core idea of ​​OPC is to establish an optical proximity correction model based on the consideration of counteracting the optical proximity effect. The photomask pattern is designed according to the optical proximity correction model. In this way, although the lithographic pattern and the corresponding photomask pattern have optical proximity effect, the cancellation of this phenomenon has been considered when designing the photomask pattern according to the optical proximity correction model. Therefore, the lithographic pattern after photolithography is close to the target pattern actually desired by the user.

[0004] However, as design dimensions continue to shrink, current optical proximity correction methods may fail to converge effectively at nodes of 10nm and below, affecting the accuracy of optical proximity correction.

[0005] Therefore, it is necessary to provide a more efficient and reliable technical solution that can still guarantee the accuracy of optical proximity correction at 10nm and below nodes. Summary of the Invention

[0006] This application provides an optical proximity correction method that can still guarantee the accuracy of optical proximity correction at nodes of 10nm and below.

[0007] This application provides an optical proximity correction method, comprising: providing a target image, the target image including a plurality of first sub-images arranged in an array, each first sub-image including a rectangle, the rectangle including a short side along the horizontal direction and a long side along the vertical direction; obtaining a virtual image based on the target image, moving both long sides of each first sub-image inward by a distance ΔV and moving both short sides of each first sub-image outward by a distance ΔH to obtain a plurality of second sub-images, the plurality of second sub-images being the virtual image; and performing optical proximity correction based on the virtual image to obtain a photomask image.

[0008] In some embodiments of this application, the ΔV satisfies the following condition:

[0009]

[0010] Among them, MRC S The spacing parameters are defined by the mask rules; S1 is the horizontal spacing between adjacent first sub-patterns; W is the short side dimension of the first sub-pattern; MRC W Limit the width parameter for the photomask rule.

[0011] In some embodiments of this application, the range of ΔV is 0.1-50 nanometers.

[0012] In some embodiments of this application, the ΔH satisfies the following condition:

[0013]

[0014] Where S2 is the vertical spacing between adjacent first sub-figures; C is any positive number.

[0015] In some embodiments of this application, C is less than or equal to the minimum segment value in the optical proximity correction parameter.

[0016] In some embodiments of this application, the range of C is 0-50 nanometers.

[0017] In some embodiments of this application, the range of ΔH is 0.1-50 nanometers.

[0018] In some embodiments of this application, the method for optical proximity correction based on the virtual graphic includes: segmenting the virtual graphic, dividing the boundary of the virtual graphic into multiple segments; performing optical proximity correction operation on the segmented virtual graphic to obtain a corrected graphic; performing simulated lithography on the corrected graphic to obtain a simulated graphic; comparing the edge position error between the simulated graphic and the target graphic, and when the edge position error between the simulated graphic and the target graphic is greater than a threshold, moving the positions of the multiple segments, and re-performing the optical proximity correction operation and simulated lithography until the edge position error between the simulated graphic and the target graphic is less than or equal to the threshold, and using the corrected graphic corresponding to the simulated graphic as a photomask graphic.

[0019] In some embodiments of this application, the virtual graphics are segmented based on segmentation rules.

[0020] In some embodiments of this application, the length of the longer side is greater than the length of the shorter side.

[0021] This application provides an optical proximity correction method, which obtains a corresponding virtual image based on a target image, and then performs optical proximity correction based on the virtual image to obtain a photomask image. The method can still ensure the accuracy of optical proximity correction at nodes of 10nm and below. Attached Figure Description

[0022] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale.

[0023] in:

[0024] Figure 1 This is a flowchart of the optical proximity correction method described in the embodiments of this application;

[0025] Figure 2 This is a schematic diagram of the target pattern in the optical proximity correction method described in the embodiments of this application;

[0026] Figure 3 This is a schematic diagram illustrating the structural differences between the virtual graphic and the target graphic in the optical proximity correction method described in this application embodiment. Detailed Implementation

[0027] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0028] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0029] In some optical proximity correction (OPC) methods, after providing a target image, the edges of the target image are divided into small segments. By moving the positions of these segments and performing model simulation, the edge placement error (EPE) between the current simulated image and the target image is obtained, and the segment movement position for the next iteration is calculated. Finally, after dozens of iterations, the simulated image and the target image are brought as close as possible. The new image obtained after each segment movement is the OPC correction result, used for subsequent mask fabrication. Therefore, accelerating iterative convergence to reduce EPE is key to the OPC correction process.

[0030] However, as the pattern spacing continues to decrease, using the above method at nodes of 10nm and below may result in OPC results failing to converge effectively. Because two adjacent target patterns are too close, the spacing between them is smaller than the MRC setting (mask rule constraint, representing mask fabrication capability and one of the limiting parameters in the OPC fragment movement process). This prevents fragments that should move outward from moving normally due to MRC limitations, leading to a significant difference between the simulated pattern after OPC correction and the target pattern. Fabricating a mask based on this result will ultimately affect device performance.

[0031] To address the aforementioned issues, this application provides an optical proximity correction method. This method obtains a corresponding virtual image based on a target image, and then performs optical proximity correction based on the virtual image to obtain a photomask image. This method can still guarantee the accuracy of optical proximity correction at nodes of 10nm and below.

[0032] Figure 1 This is a flowchart of the optical proximity correction method described in an embodiment of this application. The optical proximity correction method described in the embodiment of this application will be described in detail below with reference to the accompanying drawings.

[0033] This application provides an optical proximity correction method, referencing... Figure 1 As shown, it includes:

[0034] Step S1: Provide a target graphic, the target graphic including a plurality of first sub-graphics arranged in an array, the first sub-graphic including a rectangle, the rectangle including a short side along the horizontal direction and a long side along the vertical direction;

[0035] Step S2: Based on the target graphic, obtain a virtual graphic, move the two long sides of each first sub-graphic inward by a distance ΔV and move the two short sides of each first sub-graphic outward by a distance ΔH to obtain several second sub-graphics, which are the virtual graphic;

[0036] Step S3: Perform optical proximity correction based on the virtual graphic to obtain the photomask graphic.

[0037] This application provides an optical proximity correction method, which obtains a corresponding virtual image based on a target image, and then performs optical proximity correction based on the virtual image to obtain a photomask image, thus avoiding the problem of reduced accuracy of optical proximity correction when the target image is at a node of 10nm and below.

[0038] Figure 2 This is a schematic diagram of the target pattern in the optical proximity correction method described in the embodiments of this application.

[0039] refer to Figure 1 and Figure 2 As shown, in step S1, a target pattern 100 is provided, which includes a plurality of first sub-patterns 101 arranged in an array. Specifically, the target pattern 100 includes multiple rows of first sub-patterns 101, with each row containing multiple first sub-patterns 101. The first sub-patterns 101 in adjacent rows are staggered, meaning they are not aligned. The target pattern 100 is a target for optical proximity correction, meaning that ideally, the photolithographic pattern formed on the substrate is consistent with the target pattern 100.

[0040] Continue to refer to Figure 2 As shown, the first sub-shape 101 includes a rectangle, which includes a short side along the horizontal direction and a long side along the vertical direction. It should be noted that, unless otherwise specified, the horizontal and vertical orientations mentioned in the embodiments of this application are based on the orientations shown in the accompanying drawings.

[0041] In some embodiments of this application, the length of the longer side is greater than the length of the shorter side.

[0042] Continue to refer to Figure 2 As shown, the horizontal spacing between adjacent first sub-figures 101 is marked as S1. The vertical spacing between adjacent first sub-figures 101 is marked as S2. The shorter side dimension (or width) of the first sub-figure 101 is marked as W.

[0043] In 10nm and below technology nodes, the horizontal and vertical spacing of adjacent first sub-patterns 101 is very small, already less than the MRC setting value (mask rule constraint, representing mask fabrication capability, one of the limiting parameters in the OPC segment movement process). During OPC correction, if segmentation and segment movement are directly performed based on the target pattern 100, segments that were originally intended to move outward may not be able to move normally due to MRC constraints, resulting in a significant difference between the simulated pattern after OPC correction and the target pattern. If a mask is fabricated based on this result, it will ultimately affect device performance.

[0044] Therefore, in the technical solution of this application, instead of directly using the target graphic 100 as the basis for optical proximity correction, the target graphic 100 is first processed to obtain a virtual graphic that meets the MRC limit, and then optical proximity correction is performed based on the virtual graphic. This avoids the problem that the accuracy of OPC correction results is affected because the target graphic 100 does not meet the MRC limit.

[0045] Figure 3This is a schematic diagram illustrating the structural differences between the virtual graphic and the target graphic in the optical proximity correction method described in this application embodiment.

[0046] refer to Figure 1 and Figure 3 As shown, in step S2, a virtual graphic 200 is obtained based on the target graphic 100. The two long sides of each first sub-graphic 101 are moved inward by a distance ΔV (i.e., the width of the short side is shortened) and the two short sides of each first sub-graphic 101 are moved outward by a distance ΔH (i.e., the length of the long side is increased) to obtain a number of second sub-graphics 201, which are the virtual graphic 200.

[0047] The virtual graphics 200 needs to meet MRC restrictions.

[0048] First, the width (short side dimension) of each second sub-graphic 201 in the virtual graphic 200 needs to meet the width limit parameter MRC of the photomask rule. W .

[0049] That is, W-2ΔV≥MRC W .

[0050] Second, the horizontal spacing between adjacent second sub-graphics 201 in the virtual graphic 200 needs to meet the photomask rule constraint spacing parameter MRC. S .

[0051] That is, S1+2ΔV≥MRC S .

[0052] Combining the first and second points above, we can conclude that ΔV satisfies the following condition:

[0053]

[0054] Among them, MRC S The spacing parameters are defined by the mask rules; S1 is the horizontal spacing between adjacent first sub-patterns; W is the short side dimension of the first sub-pattern; MRC W Limit the width parameter for the photomask rule.

[0055] In some embodiments of this application, the range of ΔV is 0.1-50 nanometers.

[0056] In order to improve OPC convergence efficiency while ensuring that the virtual graphic 200 meets the MRC constraints, this application also sets the long side dimension (length) of the second sub-graphic 201 in the virtual graphic 200.

[0057] Specifically, the minimum value of ΔH is half the vertical spacing between adjacent first sub-figures 101 in the target figure 100, so that there is a certain orthogonal projection between the second sub-figures 201 of the obtained virtual figure 200 to facilitate OPC convergence; the maximum value of ΔH is the minimum value plus a constant C, where C can be any positive number, and it is recommended that it not exceed the minimum segment value set in the OPC parameters to facilitate segmentation and convergence.

[0058] In some embodiments of this application, the ΔH satisfies the following condition:

[0059]

[0060] Where S2 is the vertical spacing between adjacent first sub-figures; C is any positive number.

[0061] In some embodiments of this application, C is less than or equal to the minimum segment value in the optical proximity correction parameter.

[0062] In some embodiments of this application, the range of C is 0-50 nanometers.

[0063] In some embodiments of this application, the range of ΔH is 0.1-50 nanometers.

[0064] In the technical solution of this application, a virtual graphic that meets the MRC limit is obtained based on the target graphic, and then optical proximity correction is performed based on the virtual graphic to obtain the photomask graphic. The accuracy of optical proximity correction can still be guaranteed at nodes of 10nm and below.

[0065] Continue to refer to Figure 1 As shown, in step S3, optical proximity correction is performed based on the virtual graphic 200 to obtain the photomask graphic.

[0066] In some embodiments of this application, the method for optical proximity correction based on the virtual graphic 200 includes: segmenting the virtual graphic 200, dividing the boundary of the virtual graphic 200 (specifically, the edge of each second sub-graphic 201) into multiple segments; performing optical proximity correction operation on the segmented virtual graphic 200 to obtain a corrected graphic (or OPC polygon); performing simulated lithography on the corrected graphic to obtain a simulated graphic; comparing the edge position error (EPE) between the simulated graphic and the target graphic, and when the edge position error between the simulated graphic and the target graphic 100 is greater than a threshold, moving the positions of the multiple segments, and re-performing the optical proximity correction operation and simulated lithography until the edge position error between the simulated graphic and the target graphic is less than or equal to the threshold, and using the corrected graphic corresponding to the simulated graphic as a photomask graphic.

[0067] In some embodiments of this application, the virtual graphic 200 is segmented based on a segmentation rule. In this embodiment, the virtual graphic 200 is segmented based on a segmentation rule. An equal division method can be used to segment the virtual graphic 200, dividing the boundaries of the virtual graphic 200 into multiple segments.

[0068] Specifically, in this embodiment, the boundary of the second sub-graphic 201 of the virtual graphic 200 includes a long side and a short side. The method for segmenting the virtual graphic 200 includes: dividing the long side of the second sub-graphic 201 into multiple first segments; and dividing the short side of the second sub-graphic 201 into one or multiple second segments.

[0069] It should be noted that in other embodiments, user-defined segmentation rules can also be used to segment the virtual graphic 200, dividing the boundary of the virtual graphic 200 into multiple segments.

[0070] The optical proximity correction operation includes multiple iterative calculations. During the optical proximity correction operation, the position of the first segment moves inward or outward, and the position of the second segment moves inward or outward, until all segments converge iteratively and the edge position error is within a preset range.

[0071] Specifically, the modified pattern (or OPC polygon) satisfies the following: simulated lithography is performed on the modified pattern (or OPC polygon) to obtain a simulated lithographic pattern; the positional difference between the simulated lithographic pattern and the target pattern is compared to obtain the edge position error EPE of the simulated lithographic pattern, and the edge position error EPE is within a preset range.

[0072] Traditional OPC correction methods that involve segmentation and movement on the target pattern are no longer sufficient to meet the process requirements of complex patterns at 10nm and below nodes. Therefore, this application proposes a novel optical proximity correction method to address the problem of OPC failing to converge due to MRC limitations caused by overly close patterns. The technical solution of this application generates an additional virtual pattern on top of the target pattern through pattern processing. This virtual pattern serves as the object for the first step of OPC segmentation and movement, while the original target pattern remains the actual target for calculating EPE during OPC iteration. This method yields an initial OPC segmentation / movement pattern that meets MRC requirements, ensuring OPC result convergence. The applicant's test results show that the OPC EPE obtained by the technical solution of this application is significantly better than that of traditional methods, with the contour line being closer to the target pattern. This indicates that the method provided in this application can effectively help improve the process window and increase yield.

[0073] This application provides an optical proximity correction method, which obtains a corresponding virtual image based on a target image, and then performs optical proximity correction based on the virtual image to obtain a photomask image. The method can still ensure the accuracy of optical proximity correction at nodes of 10nm and below.

[0074] In summary, after reading this application, those skilled in the art will understand that the foregoing application content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.

[0075] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.

[0076] It should also be understood that the terms “comprising,” “containing,” “including,” or “comprise”, when used in this application, indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof.

[0077] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.

[0078] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Therefore, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. Thus, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

Claims

1. An optical proximity correction method, characterized in that, include: A target graphic is provided, the target graphic comprising a plurality of first sub-graphics arranged in an array, the first sub-graphics comprising a rectangle, the rectangle comprising a short side along the horizontal direction and a long side along the vertical direction; Based on the target graphic, a virtual graphic is obtained. The two long sides of each first sub-graphic are moved inward by a distance ΔV and the two short sides of each first sub-graphic are moved outward by a distance ΔH to obtain several second sub-graphics. The several second sub-graphics are the virtual graphic. Optical proximity correction is performed based on the virtual graphic to obtain the photomask pattern; The ΔV satisfies the following condition: ； in, The spacing parameters are limited by the photomask rules; The horizontal spacing between adjacent first sub-figures; The dimension of the shorter side of the first sub-figure; Limit the width parameter for the photomask rule; The ΔH satisfies the following condition: ； in, denoted as the vertical spacing between adjacent first sub-figures; C is any positive number.

2. The optical proximity correction method as described in claim 1, characterized in that, The range of ΔV is 0.1-50 nanometers.

3. The optical proximity correction method as described in claim 1, characterized in that, C is less than or equal to the smallest segment value in the optical proximity correction parameter.

4. The optical proximity correction method as described in claim 3, characterized in that, The range of C is 0-50 nanometers.

5. The optical proximity correction method as described in claim 1, characterized in that, The range of ΔH is 0.1-50 nanometers.

6. The optical proximity correction method as described in claim 1, characterized in that, The method for optical proximity correction based on the virtual graphics includes: The virtual graphic is segmented, and the boundary of the virtual graphic is divided into multiple segments; Perform optical proximity correction calculations on the segmented virtual graphics to obtain the corrected graphics; The modified pattern is subjected to simulated photolithography to obtain a simulated pattern; The edge position error between the simulated pattern and the target pattern is compared. When the edge position error between the simulated pattern and the target pattern is greater than a threshold, the positions of the multiple segments are moved, and optical proximity correction calculation and simulated lithography are performed again until the edge position error between the simulated pattern and the target pattern is less than or equal to the threshold. The corrected pattern corresponding to the simulated pattern is used as the photomask pattern.

7. The optical proximity correction method as described in claim 6, characterized in that, The virtual graphics are segmented based on segmentation rules.

8. The optical proximity correction method as described in claim 1, characterized in that, The length of the longer side is greater than the length of the shorter side.

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