OPC correction method for optimizing metal layer pattern

Abstract

The invention discloses an OPC (Optical Proximity Correction) method for optimizing a metal layer pattern. The method comprises the following steps of: 1, acquiring a first pattern with insufficient light intensity in the metal layer pattern; step 2, screening each edge in the first graph to obtain a first edge with the problem of insufficient light intensity; 3, the number and the positions of the correction points on the first edge are adjusted, and it is guaranteed that the width of the first graph can be enlarged to guarantee that the light intensity of the first graph is increased when the mask plate is generated and model fitting is conducted through the set correction points. According to the invention, the light intensity of a metal layer pattern, especially a comb-shaped pattern, with insufficient light intensity can be increased.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor integrated circuit, and in particular to an optical proximity correction (OPC) method for optimizing metal layer patterns. Background Art

[0002] Because metal layer patterns are complex and diverse, additional factors must be considered when correcting specific edges. The surrounding environment of these patterns is unique, which results in the inability to perform proper corrections on specific edges during optical proximity correction due to space limitations. This ultimately results in the width of the pattern corresponding to these edges being too small, indirectly leading to insufficient light intensity at these locations, making them unable to meet process requirements.

[0003] like Figure 1 As shown, it is a schematic diagram of a metal layer pattern with a problem of insufficient light intensity in the prior art; the metal layer pattern includes a comb pattern, which is formed by a plurality of patterns arranged crosswise. Figure 2 Taking the graphic 101a in FIG. 1 as an example, due to the structural limitation of the graphic 101a itself, it is easy to cause the problem of insufficient light intensity and eventually reduce the width.

[0004] There is an adjacent graphic on each side of the graphic 101a. Figure 1 In FIG. 1 , two adjacent graphics are marked with markers 101b and 101c, respectively.

[0005] Among them, adjacent pattern 101b is located in the middle area of ​​the comb pattern. Its neighbor is another pattern 101a. That is, adjacent pattern 101b and pattern 101a are structurally symmetrical, both have the same problem, and will undergo the same OPC correction. Adjacent pattern 101c is located at the edge of the comb pattern. It is not adjacent to pattern 101a, and the OPC corrections between adjacent pattern 101c and pattern 101a are not exactly the same.

[0006] The position having the problem of insufficient light intensity in the pattern 101a is located at the boundary position of the pattern 101a.

[0007] Figure 1 In the example, the width between the two sides of the graphic 101a is the minimum width.

[0008] The sum of the width of the pattern 101a and the width of the adjacent space is a pitch, and the size of the pitch is the minimum pitch. Figure 1In the example, the width of pattern 101a and the spacing between it and its adjacent pattern 101c on the left, and the corresponding stepping, are the minimum pitch. The spacing between pattern 101a and its adjacent pattern 101b on the right, and the corresponding stepping, are also the minimum pitch. Because both steppings are minimum, the process window for OPC correction of pattern 101a is small, making it prone to defects such as insufficient light intensity and width reduction below the minimum width.

[0009] Figure 1 , a pattern 102a corrected according to the regular OPC corresponding to the pattern 101a, a pattern 102b corrected according to the regular OPC corresponding to the adjacent pattern 101b, and a pattern 102c corrected according to the regular OPC corresponding to the adjacent pattern 101c are also shown.

[0010] In the existing method, a correction point (site) operation needs to be performed, that is, a correction point needs to be set and a model-based OPC correction (MBOPC) needs to be performed according to the setting of the correction point.

[0011] like Figure 2 As shown, the existing OPC correction Figure 1 The following diagram illustrates the site operation for a specific graphic. For graphic 101a, multiple correction points 103a and 103b are required. Correction point 103a reduces the width of the edges, while correction point 103b increases the width between the edges. The correction point settings for adjacent graphic 101b are the same as for graphic 101a. For adjacent graphic 101c, multiple correction points 103c are also required.

[0012] like Figure 3 As shown, it is along Figure 2 The light intensity distribution curve in the width direction of the metal layer pattern with insufficient light intensity is shown; it can be seen that the maximum light intensity is 0.163, and a smaller light intensity value will reduce the width of the simulated outline of the pattern 101a.

[0013] like Figure 4 As shown, it is the Figure 2 The graph after the site operation is subjected to MBOPC simulation; graph 104a is the graph obtained by model fitting of graph 102a. It can be seen that in the bottom area, the width w101 of graph 104a is smaller than the width w100 of graph 101a, and the width w100 is the target width. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to provide an OPC correction method for optimizing metal layer patterns, which can increase the light intensity of metal layer patterns with insufficient light intensity.

[0015] To solve the above technical problems, the present invention provides an OPC correction method for optimizing metal layer patterns, comprising the following steps:

[0016] Step 1: Obtain a first pattern with insufficient light intensity in a metal layer pattern.

[0017] Step 2: Screening each edge in the first graph to obtain a first edge with insufficient light intensity.

[0018] Step 3: Adjust the number and position of the correction points on the first side, and set the correction points to ensure that the width of the first pattern is expanded to increase the light intensity of the first pattern when generating the mask and performing model fitting.

[0019] A further improvement is that the first pattern includes a comb-shaped pattern.

[0020] There is an adjacent graphic on each side of the first graphic.

[0021] A further improvement is that the position in the first graphic where the light intensity problem occurs is located at a boundary position of the first graphic.

[0022] A further improvement is that, in step 2, each of the first edges is screened out at a boundary position of the first graphic.

[0023] A further improvement is that in step 2, the number of the first edges screened in the first graphic includes two, the two first edges are the length edges of the first graphic; and each first edge and the corresponding edge of the adjacent graphic have a spacing area.

[0024] A further improvement is that the width of the first graphic between two of the first sides is the minimum width.

[0025] The sum of the width of the first pattern and the width of the adjacent spaced area is a step, and the size of the step is a minimum step.

[0026] A further improvement is that, in step three, the number of the correction points on the two first sides is two and the correction points on the two first sides are symmetrically arranged along the center line in the length direction of the first figure.

[0027] A further improvement is that one of the correction points on the first side is located above the width top edge of the adjacent figure and another correction point is located below the width top edge of the adjacent figure.

[0028] A further improvement is that the model fitting is implemented using MBOPC.

[0029] A further improvement is that, during the OPC correction process, the widths of the two correction points of the two first sides located above the width top edge of the adjacent pattern are greater than the widths of the two correction points located below the width top edge of the adjacent pattern.

[0030] A further improvement is that the adjacent pattern is located in the middle area of ​​the comb-shaped pattern, and the adjacent pattern is another of the first patterns;

[0031] Alternatively, the adjacent pattern is located in an edge region of the comb-shaped pattern, and the adjacent pattern is not the first pattern.

[0032] For the special pattern in the metal layer, namely the first pattern, especially the comb-shaped pattern, which has the problem of insufficient light intensity, the present invention optimizes the number and position of the correction points, and can optimize the size of the first pattern in the mask during the subsequent program iteration process, thereby increasing the light intensity of the special pattern and improving the process window. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0034] Figure 1 It is a schematic diagram of a metal layer pattern having a problem of insufficient light intensity in the prior art;

[0035] Figure 2 Is the existing OPC correction Figure 1 Schematic diagram of the site operation of the graphic shown;

[0036] Figure 3 It is along Figure 2 Light intensity distribution curve in the width direction of the metal layer pattern with insufficient light intensity;

[0037] Figure 4 It's about passing Figure 2 The graphics after site operation are the graphics after MBOPC simulation;

[0038] Figure 5 is a flow chart of an OPC correction method for optimizing metal layer patterns according to an embodiment of the present invention;

[0039] Figure 6 is a schematic diagram of a first pattern in an OPC correction method for optimizing a metal layer pattern according to an embodiment of the present invention;

[0040] Figure 7 1 is a schematic diagram of a site operation of a first pattern by an OPC correction method for optimizing a metal layer pattern according to an embodiment of the present invention;

[0041] Figure 8 It is through Figure 7A light intensity distribution curve along the width direction of the first graphic after the site operation;

[0042] Figure 9 It's about passing Figure 7 The first graphic after the site operation is the graphic after the MBOPC simulation is performed. DETAILED DESCRIPTION

[0043] like Figure 5 FIG. 1 is a flow chart of an OPC correction method for optimizing metal layer patterns according to an embodiment of the present invention; FIG. Figure 6 FIG. 2 is a schematic diagram of a first pattern 201 a in an OPC correction method for optimizing a metal layer pattern according to an embodiment of the present invention. The OPC correction method for optimizing a metal layer pattern according to an embodiment of the present invention includes the following steps:

[0044] Step 1: Obtain a first pattern 201a having insufficient light intensity in a metal layer pattern.

[0045] In the embodiment of the present invention, the first pattern 201a includes a comb-shaped pattern.

[0046] There is an adjacent graphic on each side of the first graphic 201a. Figure 6 In FIG, two adjacent graphics are marked with markers 201b and 201c respectively.

[0047] The adjacent pattern 201b is located in the middle area of ​​the comb-shaped pattern and is another of the first pattern 201a. That is, the adjacent pattern 201b and the first pattern 201a are symmetrical in structure, have the same problem, and will undergo the same OPC correction.

[0048] The adjacent pattern 201c is located at the edge area of ​​the comb-shaped pattern. The adjacent pattern is not the first pattern 201a, that is, the OPC corrections between the adjacent pattern 201c and the first pattern 201a are not exactly the same.

[0049] The location of the first graphic 201a having the problem of insufficient light intensity is located at the boundary of the first graphic 201a.

[0050] Figure 6 , also displayed are a graphic 202a corrected according to regular OPC corresponding to the first graphic 201a, a graphic 202b corrected according to regular OPC corresponding to the adjacent graphic 201b, and a graphic 202c corrected according to regular OPC corresponding to the adjacent graphic 201c.

[0051] Step 2: Screen each edge in the first graphic 201a to obtain a first edge with insufficient light intensity.

[0052] In the embodiment of the present invention, each of the first edges is screened out at a boundary position of the first graphic 201 a .

[0053] The number of the first edges screened in the first graphic 201a includes two, and the two first edges are the length edges of the first graphic 201a; each of the first edges and the corresponding edge of the adjacent graphic has a spacing area.

[0054] The width of the first graphic 201a between two first sides is the minimum width.

[0055] In some embodiments, the sum of the width of the first pattern 201 a and the width of the adjacent spacer is a pitch, and the size of the pitch is a minimum pitch. Figure 6 In the example, the width of the first pattern 201a and the spacing between the adjacent pattern 201c on the left and the corresponding stepping are the minimum pitch. The spacing between the first pattern 201a and the adjacent pattern 201b on the right and the width of the adjacent pattern 201b and the corresponding stepping are also the minimum pitch. Because both steppings are minimum, the process window for OPC correction of the first pattern 201a is small, making it easy to cause defects such as insufficient light intensity and width reduction below the minimum width.

[0056] Step 3: Adjust the number and position of the correction points on the first side, and set the correction points to ensure that the width of the first graphic 201a is expanded when generating the mask and performing model fitting to ensure that the light intensity of the first graphic 201a is increased.

[0057] In the embodiment of the present invention, Figure 7 As shown, the number of the correction points on the two first sides is two, and the correction points on the two first sides are symmetrically arranged along the center line in the length direction of the first graphic 201a.

[0058] One of the correction points 203a on the first side is located above the width top side of the adjacent figure, and the other correction point 203b is located below the width top side of the adjacent figure.

[0059] During the OPC correction process, the widths of the two correction points of the two first sides located above the width top edge of the adjacent graphics are greater than the widths of the two correction points located below the width top edge of the adjacent graphics.

[0060] like Figure 7 As shown, the adjacent graph 201b also adopts the same setting of the correction points as the first graph 201a. However, the correction points 203c set in the adjacent graph 201c are the same as those in the existing method, such as Figure 2The setting of the correction point 103c in is the same.

[0061] like Figure 8 As shown, it is through Figure 7 A light intensity distribution curve along the width direction of the first graphic after the site operation; Figure 8 In the embodiment of the present invention, the light intensity of the first pattern 201a reaches 0.181, and Figure 3 Compared with 0.163, the embodiment of the present invention can increase the light intensity of the first graphic 201a.

[0062] In the embodiment of the present invention, the model fitting is implemented using MBOPC. Figure 9 As shown, it is the Figure 7 The first graphic after the site operation is performed is the graphic after the MBOPC simulation; Figure 9 In the figure, the figure 204a is the figure obtained by fitting the first figure 201a with the model. It can be seen that the figure 204a and the first figure 201a overlap well, and the width w201 of the two is basically the same, that is, the simulated structure is consistent with the target. Figure 4 The simulated width w101 is smaller than the target width w100.

[0063] Therefore, the embodiment of the present invention can enhance the light intensity of the first pattern 201 a and thereby increase the width of the first pattern 201 a.

[0064] For the special pattern in the metal layer having the problem of insufficient light intensity, namely the first pattern 201a, especially the comb-shaped pattern, the embodiment of the present invention optimizes and adjusts the number and position of the correction points, thereby optimizing the size of the first pattern 202a in the mask during the subsequent program iteration process, thereby increasing the light intensity of the special pattern and improving the process window.

[0065] In the embodiment of the present invention, by applying restriction conditions to a pattern, a special pattern with insufficient light intensity is obtained. The special pattern is a comb-shaped pattern with high repeatability and is located at the boundary of the comb-shaped pattern.

[0066] Afterwards, the special edges of special graphics with light intensity issues at the boundaries are screened out;

[0067] Afterwards, the number and position of sites on this edge are adjusted. When generating the mask template and the subsequent model fitting, the width of the pattern at this location can be expanded, thereby increasing the light intensity at this location.

[0068] In the embodiment of the present invention, the width of the special pattern, ie, the first pattern, is enlarged, and the corresponding light intensity is also enhanced.

[0069] The fitting results of special graphics are more stable and more accurate;

[0070] Therefore, the embodiment of the present invention solves the light intensity problem at the root, reduces the secondary repair actions of the subsequent optical proximity correction inspection, and saves a lot of time.

[0071] The present invention has been described in detail above by means of specific embodiments, but these do not constitute limitations of the present invention. Without departing from the principles of the present invention, those skilled in the art may make many variations and improvements, which should also be considered as the scope of protection of the present invention.

Claims

1. An OPC correction method for optimizing metal layer patterns, characterized in that: The steps include: Step 1: obtaining a first pattern with insufficient light intensity in a metal layer pattern; Step 2: Screening each edge in the first graph to obtain a first edge with insufficient light intensity; Step 3: Adjust the number and position of the correction points on the first side, and set the correction points to ensure that the width of the first pattern is expanded to increase the light intensity of the first pattern when generating the mask and performing model fitting.

2. The OPC correction method for optimizing metal layer patterns according to claim 1, wherein: The first pattern includes a comb-shaped pattern; There is an adjacent graphic on each side of the first graphic.

3. The OPC correction method for optimizing metal layer patterns according to claim 2, wherein: The position of the first graphic having the problem of insufficient light intensity is located at a boundary position of the first graphic.

4. The OPC correction method for optimizing metal layer patterns according to claim 3, wherein: In step 2, each of the first edges is selected at a boundary position of the first graphic.

5. The OPC correction method for optimizing metal layer patterns according to claim 3, wherein: In step 2, the number of the first edges screened in the first graphic includes two, and the two first edges are length edges of the first graphic; each of the first edges and the corresponding edge of the adjacent graphic has a spacing area.

6. The OPC correction method for optimizing metal layer patterns according to claim 5, wherein: The width of the first figure between two of the first sides is the minimum width; The sum of the width of the first pattern and the width of the adjacent spaced area is a step, and the size of the step is a minimum step.

7. The OPC correction method for optimizing metal layer patterns according to claim 5, wherein: In step three, the number of the correction points on the two first sides is two, and the correction points on the two first sides are symmetrically arranged along the center line in the length direction of the first figure.

8. The OPC correction method for optimizing metal layer patterns according to claim 7, wherein: One of the correction points on the first side is located above the width top side of the adjacent figure and another of the correction points is located below the width top side of the adjacent figure.

9. The OPC correction method for optimizing metal layer patterns according to claim 8, wherein: The model fitting was achieved using MBOPC.

10. The OPC correction method for optimizing metal layer patterns according to claim 9, wherein: During the OPC correction process, the widths of the two correction points of the two first sides located above the width top edge of the adjacent graphics are greater than the widths of the two correction points located below the width top edge of the adjacent graphics.

11. The OPC correction method for optimizing metal layer patterns according to claim 2, wherein: The adjacent graphic is located in the middle area of ​​the comb-shaped graphic, and the adjacent graphic is another first graphic; Alternatively, the adjacent pattern is located in an edge region of the comb-shaped pattern, and the adjacent pattern is not the first pattern.

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