Method for correcting optical proximity effects
By merging rectangular graphic transformation structures into the target graphic, the problems of insufficient compensation for diagonal structures and the minimum size limitation of the photomask in the prior art are solved, resulting in better exposure effects and avoiding graphic distortion and size mismatch issues.
Patent Information
- Application Number
- CN202210235443.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-11
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2042-03-11
AI Technical Summary
Existing technologies are prone to insufficient compensation or limitations imposed by the minimum size of the photomask when dealing with corner-to-corner structures in complex environments, resulting in distorted exposure patterns or dimensions that do not meet requirements.
By defining a hotspot structure in the target pattern, a rectangular pattern is merged to transform the structure. The long side of the rectangular pattern is parallel to the sides of the two convex corner structures, the short side is perpendicular to the sides of the convex corner structures, and its center point is located at the midpoint between the two vertices of the convex corner structures. Optical proximity effect correction is performed to obtain the third pattern and expose it on the wafer.
It achieves better correction results, avoids MRC errors, and ensures that the key dimensions at the center of the graphic match the target values, which is superior to traditional correction methods.
Smart Images
Figure CN114740688B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor technology, and in particular to a method for correcting optical proximity effect. BACKGROUND
[0002] With the continuous development of semiconductor process technology, the feature size of layout pattern is getting smaller and smaller, and the vertical layout corner inevitably produces rounding distortion phenomenon when exposed and imaged on the silicon wafer due to the resolution limit of optical imaging. Especially at the node below 28nm, double exposure technology is introduced, such as POC (gate line end cut pattern) of 28nm and M0C (metal 0 layer cut pattern) of 14Finfet, which has complex pattern structure and inevitably produces some corner-to-corner structures. Further, FAB OPC (optical proximity effect correction) often adds some cut patterns to reduce the hot spot structure of the gate or metal layer when processing, which also increases the generation of corner-to-corner structures. In addition, most of the ion implantation layers at the node of 28nm and below are generated by logical operation on the original design layer, and simple logical operation cannot guarantee that the generated pattern can fully meet the photolithography process friendly, which will also produce a large number of corner-to-corner structures that can easily cause hot spots.
[0003] For these corner-to-corner structures, due to the rounding distortion effect, if not well corrected and compensated, it will often cause many problems, such as causing the actual ion implantation layer pattern to be closer to the previous layer pattern, causing the size of the pattern corner to be reduced, or causing the mask size to violate the minimum mask size requirement, resulting in these corner-to-corner structures becoming actual process hot spots with insufficient window in the process.
[0004] The prior art is to use optical proximity correction (OPC) to correct, and directly use rule-based optical proximity correction (rule-based OPC) and model-based optical proximity correction (model-based OPC) to compensate for the original pattern in turn. However, for such problem structures in complex environment, it is easy to appear insufficient compensation or unable to compensate due to the limitation of mask rule check (MRC), as shown in FIG. 1(a), the final exposed pattern has obvious corner pattern distortion, and the size of the pattern center position is obviously smaller than the target value. Further, the traditional correction method is to directly and completely fill the opposite part, but due to the rounding effect, the size of the pattern center position will be larger than the target value (as shown in FIG. 1(b)), or the distance itself is smaller than the MRC size, which will cause MRC error (as shown in FIG. 2(b)). SUMMARY
[0005] In view of the above-mentioned defects of the prior art, the purpose of the present application is to provide a method for correcting optical proximity effect, which is used to solve the problem that the optical proximity correction method is usually used in the prior art to correct, but for such a structure in a complex environment, it is easy to appear undercompensation or unable to compensate due to the limitation of the minimum size structure of the mask, and the corner pattern distortion of the finally exposed pattern is obvious, and the size of the center position of the pattern is obviously smaller than the target value, and the further correction method is to directly and completely fill the opposite part, but due to the corner effect, the size of the center position of the pattern will be greater than the target value, or due to the distance itself being smaller than the MRC size, the MRC error is caused.
[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for correcting optical proximity effect, comprising:
[0007] Step one, obtaining a first layout containing a target pattern;
[0008] Step two, defining a hot spot structure in the target pattern, the hot spot structure satisfying:
[0009] Two adjacent convex corner structures, and the adjacent side length of the convex corner structure is greater than the minimum layout design pattern size; and the distance between the opposite sides of the two convex corners is not less than a set distance;
[0010] Step three, merging a rectangular pattern between the two opposite convex corner structures, the long side of the rectangular pattern being parallel to the opposite sides of the two convex corner structures, the short side of the rectangular pattern being perpendicular to the opposite sides of the two convex corner structures, and the center point of the rectangular pattern being located at the midpoint of the straight line segment between the two top points of the two convex corner structures, thereby obtaining a second layout;
[0011] Step four, performing optical proximity effect correction on the second layout to obtain a third layout, and then exposing the third layout on a wafer through lithography.
[0012] Preferably, the included angle of the adjacent side of the convex corner structure in step two is 90 degrees.
[0013] Preferably, the set distance in step two is not less than the minimum line width size of lithography and mask.
[0014] Preferably, the set distance in step two is 15 nanometers to 80 nanometers.
[0015] Preferably, the side length of the rectangular pattern in step three is 1 to 1.8 times the minimum line width size of the mask.
[0016] Preferably, the side length of the rectangular pattern in step three is 20 nanometers to 120 nanometers.
[0017] Preferably, the parallel length of the two convex corner structures in step three is not less than the long side of the rectangular pattern, and the short side of the rectangular pattern is greater than the distance between the two convex corner structures.
[0018] Preferably, the parallel length of the two convex corner structures in step three is less than the long side of the rectangular pattern, and the short side of the rectangular pattern is greater than the distance between the two convex corner structures.
[0019] Preferably, one side of the rectangular pattern in step three has a concave corner, and the rectangular pattern is offset to the side away from the concave corner.
[0020] Preferably, the distance between the side of the rectangular pattern and the concave corner in step three is 30-200 nm.
[0021] Preferably, the offset distance of the rectangular pattern in step three is 0-15 nm.
[0022] As described above, the optical proximity effect correction method of the present application has the following beneficial effects:
[0023] The present application can obtain better correction results than traditional methods by adding a filling pattern to convert the corner-to-corner structure with small spacing, solve the problem of process hot spots caused by the distortion of the above-mentioned corner-to-corner and other special structure layout patterns, and the size is smaller than the minimum manufacturing size limit of the mask plate. The corrected results according to the present application will not cause MRC error, and the center position of the pattern key size meets the target value, and the effect is better than that of the traditional correction method. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1a The present application is shown as a comparison diagram of the method correction of prior art example one;
[0025] Figure 1b The present application is shown as a comparison diagram of the direct correction of prior art example one;
[0026] Figure 1c The present application is shown as a comparison diagram of the method correction of prior art example two;
[0027] Figure 2a The present application is shown as a comparison diagram of the method correction of prior art example two;
[0028] Figure 2b The present application is shown as a comparison diagram of the direct correction of prior art example two;
[0029] Figure 2c The present application is shown as a comparison diagram of the method correction of prior art example three;
[0030] Figure 3a The present application is shown as a comparison diagram of the method correction of prior art example three;
[0031] Figure 3b A direct modification of the prior art embodiment three is shown in the comparative schematic diagram;
[0032] Figure 3c A modified schematic diagram of the embodiment three method of the present application is shown;
[0033] Figure 3d A schematic diagram of the embodiment three method of the present application after modification is shown;
[0034] Figure 4 A schematic diagram of the modified method of the present application is shown. DETAILED DESCRIPTION
[0035] The present application will be described by specific embodiments, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied by other different specific embodiments, and each detail in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application.
[0036] Please refer to Figure 4 The present application provides a method for modifying optical proximity effect, comprising:
[0037] Step one, obtaining a first layout containing a target pattern, the first layout is a complete original layout, and also includes a reference layer;
[0038] Step two, defining a hot spot structure in the target pattern, the hot spot structure satisfies:
[0039] Two adjacent convex corner structures, and the length of the adjacent edges of the convex corner structures are both greater than the minimum layout design pattern size; and the distance between the edges of the two opposite convex corners is not less than a set distance;
[0040] In an optional embodiment, the included angle of the edge of the convex corner structure in step two is 90 degrees.
[0041] In an optional embodiment, the set distance in step two is not less than the minimum line width size of the photolithography and the photomask.
[0042] In an optional embodiment, the set distance in step two is 15 nanometers to 80 nanometers.
[0043] Step three, according to the characteristics of the hotspot structure, the structure is transformed to obtain a new low-risk layout pattern, a rectangular pattern is merged between the two convex corner structures, the long side of the rectangular pattern is parallel to the opposite side of the two convex corner structures, the short side of the rectangular pattern is perpendicular to the opposite side of the two convex corner structures, and the center point of the rectangular pattern is located at the midpoint of the straight line segment between the two top points of the two convex corner structures, thereby obtaining a second layout;
[0044] In an optional embodiment, the edge length of the rectangular pattern in step three is 1 to 1.8 times the minimum line width size of the mask.
[0045] In an optional embodiment, according to different mask accuracy levels, the edge length of the rectangular pattern in step three is usually 20 to 120 nanometers.
[0046] Step four, the second layout is subjected to optical proximity correction to obtain a third layout, which can be transferred to a mask, and then the third layout on the mask is exposed on the wafer through photolithography.
[0047] Example one
[0048] In an optional embodiment, please refer to Figure 1c , the opposite parallel length of the two convex corner structures in step three is not less than the long side of the rectangular pattern, and the short side length of the rectangular pattern is the distance between the two convex corner structures.
[0049] The complete original layout containing the target pattern and the reference layer is obtained, and two convex corners with opposite side distance less than S1 are selected, S1 is in the range of 15-80nm.
[0050] In this embodiment, the opposite parallel length of the two convex corners is greater than 2 times the minimum manufacturing size of the mask, so a filling pattern with a length of A and a width of S1 is generated with the midpoint of the line connecting the two convex corners as the center point. The added rectangular is merged with the original target pattern to obtain a new target pattern, and the new layout pattern is subjected to normal OPC processing to obtain a mask layer (the new layout pattern transferred to the mask), and the mask layer is subjected to photolithography to expose the OPC correction result on the wafer.
[0051] Wherein, the minimum manufacturing size of the mask is 20-80nm, the length A of the added filling rectangular is determined by the minimum line width size M of the mask, and the preferred size is 1-1.8 times the size of M, according to different mask accuracy levels, the value of A is 20-120nm.
[0052] In this embodiment, the modified structure of the conventional method cannot compensate for the MRC limitation, and the final exposure result has obvious corner pattern distortion, and the pattern center position size is obviously smaller than the target value, as shown in Fig. 1(a). Further, the conventional correction method directly fills the opposite part completely, but due to the corner effect, the pattern center position size will be larger than the target value (as shown in Fig. 1(b)), and the corrected result of the present embodiment will not be limited by MRC, and the pattern center position key size meets the target value, which is better than the conventional correction method.
[0053] Embodiment Two
[0054] In an alternative embodiment, referring to Figure 2c , the parallel length of the two convex corner structures in step three is less than the long side of the rectangular pattern, and the short side length of the rectangular pattern is greater than the distance between the two convex corner structures.
[0055] An original complete layout containing a target pattern and a reference layer is obtained, and two convex corners with an opposite side distance less than S1 are selected, and S1 ranges from 15 to 80 nm. In this embodiment, the parallel length L of the two convex corners is less than the minimum manufacturing size of the mask, and then a filling pattern with a length A and a width B is generated with the midpoint of the line connecting the two convex corners as the center point, and the added rectangle is combined with the original target pattern to obtain a new target pattern. The new layout pattern is subjected to normal OPC processing to obtain a mask layer. The OPC correction result is exposed on the wafer by photolithography.
[0056] wherein the minimum manufacturing size of the mask is 20-80 nm, and the length and width A and B of the added filling rectangle are determined by the minimum line width size M of the mask manufacturing, and are preferably 1-1.8 times the size of M, and according to different mask accuracy levels, the values of A and B are 20-120 nm.
[0057] In this embodiment, due to the small pitch, the correction of the conventional method has small pitch or small line width, and the exposure result will have short circuit (as shown in Fig. 2(a)) or open circuit (as shown in Fig. 2(b)) defects, which will not cause actual circuit problems, but will become noise in defect scanning and affect defect analysis, and direct filling will generate line segments smaller than the manufacturing size of the mask, resulting in MRC error. The corrected result of the present embodiment will not cause MRC error and short circuit / open circuit hot spot problem, and the pattern center position key size meets the target value, which is better than the conventional correction method.
[0058] Embodiment Three
[0059] In an alternative embodiment, referring to Figure 3c , one side of the rectangular pattern in step three has a concave corner, and then the rectangular pattern is shifted away from the side away from the concave corner.
[0060] Referring to Figure 3aIn the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3. Figure 3b
[0061] In the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3.
[0062] In the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3.
[0063] In the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3. Figure 3d
[0064] In the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3.
[0065] In the embodiment, the original target pattern is shown in Fig. 1, and the reference layer is shown in Fig. 2. The original target pattern is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S1, and S1 is in the range of 15-80 nm. The reference layer is a rectangle pattern with two opposite corners. The distance between the two opposite corners is S2, and S2 is in the range of 30-200 nm. The distance between the two opposite corners of the original target pattern and the reference layer is E, and E is in the range of 0-15 nm. The OPC process is performed on the original target pattern, and the OPC result is shown in Fig. 3.
[0066] It is to be understood that the embodiments provided in the present application are only schematic and the actual implementation of the present application can be different from the embodiments provided in the present application. The embodiments provided in the present application are only used to explain the basic concept of the present application, and the components shown in the embodiments are not drawn according to the actual number, shape and size of the components, and the actual implementation of the components can be changed arbitrarily, and the layout of the components can be more complex.
[0067] In summary, the present application can obtain better correction results than the traditional method by adding a filling pattern to the corner-to-corner structure with small spacing, and solve the problems of process hot spots caused by the distortion of the pattern of the corner-to-corner structure and the size smaller than the limit of the minimum manufacturing size of the mask plate. The corrected results according to the present application will not cause MRC error, and the critical dimension of the center position of the pattern meets the target value, which is better than the traditional correction method. Therefore, the present application effectively overcomes the shortcomings of the prior art and has high industrial utilization value.
[0068] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.
Claims
1. A method of modifying optical proximity effects, characterized by, At least comprising: Step one, obtaining a first layout containing a target pattern; Step two, defining a hot spot structure in the target pattern, the hot spot structure satisfying: Two adjacent convex corner structures, and the length of the adjacent edges of the convex corner structures is greater than the minimum layout design pattern size; and the distance between the opposite edges of the two convex corner structures is not less than a set distance; Step three, merging a rectangular pattern between the two convex corner structures, the long side of the rectangular pattern being parallel to the opposite edges of the two convex corner structures, the short side of the rectangular pattern being perpendicular to the opposite edges of the two convex corner structures, and the center point of the rectangular pattern being located at the midpoint of the straight line segment between the two top points of the two convex corner structures, and wherein the parallel length of the opposite edges of the two convex corner structures is not less than the long side of the rectangular pattern, and the short side length of the rectangular pattern is the distance between the two convex corner structures, or the parallel length of the opposite edges of the two convex corner structures is less than the long side of the rectangular pattern, and the short side length of the rectangular pattern is greater than the distance between the two convex corner structures, thereby obtaining a second layout; Step four, performing optical proximity correction on the second layout to obtain a third layout, and then exposing the third layout on a wafer through photolithography.
2. The method of modifying optical proximity effects according to claim 1, wherein: The included angle of the adjacent edges of the convex corner structure in step two is 90 degrees.
3. The method of claim 1, wherein: The set distance in step two is not less than the minimum line width size of photolithography and photomask.
4. The method of modifying optical proximity effects according to claim 3, wherein: The set distance in step two is 15 nanometers to 80 nanometers.
5. The method of claim 3, wherein: The side length of the rectangular pattern in step three is 1 to 1.8 times the minimum line width size of the photomask.
6. The method of modifying optical proximity effects according to claim 5, wherein: The side length of the rectangular pattern in step three is 20 nanometers to 120 nanometers.
7. The method of claim 1, wherein: If one side of the rectangular pattern in step three has a concave corner, the rectangular pattern is offset to the side away from the concave corner.
8. The method of modifying optical proximity effects according to claim 7, wherein: The distance between one side of the rectangular pattern in step three and the concave corner is 30 nanometers to 200 nanometers.
9. The method of claim 8, wherein: The offset distance of the rectangular pattern in step three is 0 to 15 nanometers.
Citation Information
Patent Citations
OPC (optical proximity correction) method for graph corners
CN107479331A