A contact layer OPC method

Abstract

The application provides a contact layer OPC method, which comprises the following steps: selecting a feature OPC pattern in a target pattern of a contact layer, and selecting a corresponding first sub-resolution auxiliary pattern to obtain a second sub-resolution auxiliary pattern; generating a third sub-resolution auxiliary pattern by taking a feature target pattern edge corresponding to the feature OPC pattern as a target; and performing model-based OPC according to the target pattern and the third sub-resolution auxiliary pattern to obtain a final OPC pattern. The contact layer OPC method provided by the application can improve the overall process window as a whole, avoid the generation of OPC hot spots, and improve the process window of the hot spot via pattern by optimizing the sub-resolution auxiliary pattern in the OPC processing flow, without the need to repeatedly perform the OPC flow, thereby reducing the OPC method optimization flow and OPC publishing time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microelectronic layout data optical correction, in particular to a contact layer OPC method. BACKGROUND

[0002] Model-based optical proximity correction has been widely used in the process of contact layer lithography, by compensating the size deviation caused by optical proximity effect, the accuracy of contact layer lithography can be improved significantly. In order to improve the accuracy of contact layer correction and the overall process window, sub-resolution assist features are introduced into the OPC process of contact layer in 55nm technology node, by enhancing the interference, changing the normalized image slope (NILS) of the via pattern, sub-resolution assist features not only improve the process window of contact layer pattern, but also make the OPC result more easily converge by changing the mask error enhancement factor (MEEF) of the pattern.

[0003] Sub-resolution assist features addition can be divided into rules-based sub-resolution assist features addition method and model-based sub-resolution assist features addition method, although the model-based sub-resolution assist features addition tool has higher accuracy, however, the long simulation operation time leads to the model-based sub-resolution assist features addition is still an auxiliary method; therefore, in the OPC correction process, the rules-based sub-resolution assist features addition method is still the main tool. One of the main problems of rules-based sub-resolution assist features is the conflict of adding assist features to adjacent vias, such as diagonal vias, although some rules are introduced to handle the conflict area, however, the conflict area addition rule is not suitable for all pattern structures, so different OPC hotspots will still be generated. In order to solve the OPC hotspot, the sub-resolution assist features of the related via pattern must be optimized, and the entire OPC correction process must be executed again, which will inevitably increase the overall publishing time. SUMMARY

[0004] The purpose of the present application is to provide a contact layer OPC method to improve the process window of hotspot via pattern, reduce the OPC method optimization process and OPC publishing time.

[0005] To achieve the above purpose, the present application provides a contact layer OPC method, comprising:

[0006] inputting a target pattern of a contact layer;

[0007] generating a first sub-resolution assist feature according to the target pattern;

[0008] performing a first model-based OPC correction according to the target pattern and the first sub-resolution assist feature, to obtain a first OPC pattern;

[0009] According to the first OPC pattern, a feature OPC pattern is selected, and a feature target pattern corresponding to the feature OPC pattern is obtained;

[0010] According to the feature OPC pattern and the feature target pattern, a second sub-resolution auxiliary pattern is obtained;

[0011] According to the feature target pattern and the second sub-resolution auxiliary pattern, a third sub-resolution auxiliary pattern is obtained;

[0012] According to the target pattern and the third sub-resolution auxiliary pattern, a second model-based OPC correction is performed to obtain a second OPC pattern.

[0013] In an optional embodiment of the present application, the target pattern of the contact layer comprises a square via pattern.

[0014] In an optional embodiment of the present application, generating the first sub-resolution auxiliary pattern according to the target pattern comprises:

[0015] According to the collected silicon wafer data of the sub-resolution auxiliary test pattern, a sub-resolution auxiliary pattern adding rule is established;

[0016] The sub-resolution auxiliary pattern adding rule comprises a standard sub-resolution auxiliary pattern adding rule and a conflict pattern sub-resolution auxiliary pattern adding rule.

[0017] In an optional embodiment of the present application, the first model-based OPC correction is an OPC correction based on a standard model established according to normal exposure conditions.

[0018] In an optional embodiment of the present application, the feature OPC pattern is a first OPC pattern with a length-width ratio greater than R after the target pattern is subjected to the first model-based OPC correction, wherein 1.8 < R < 2.5.

[0019] In an optional embodiment of the present application, obtaining the second sub-resolution auxiliary pattern according to the feature OPC pattern and the feature target pattern comprises:

[0020] A conflict checking region is obtained by extending outward along a vertical direction of a side length of the feature target pattern as a starting side.

[0021] The first sub-resolution auxiliary pattern that overlaps or contacts the conflict checking region is screened from the first sub-resolution auxiliary pattern.

[0022] The second sub-resolution auxiliary pattern is obtained by subtracting the first sub-resolution auxiliary pattern from the first sub-resolution auxiliary pattern.

[0023] In an alternative embodiment of the present application, the edge length extended along the feature target pattern corresponds to the short edge of the feature OPC pattern.

[0024] In an alternative embodiment of the present application, the extension distance is equal to the sum of the minimum distance from the first sub-resolution assist pattern to the target pattern and the minimum width of the first sub-resolution assist pattern.

[0025] In an alternative embodiment of the present application, the edge length extended along the feature target pattern is targeted, and the second sub-resolution assist pattern is used as the reference pattern, and the third sub-resolution assist pattern is generated according to the standard pattern sub-resolution assist pattern addition rule.

[0026] In an alternative embodiment of the present application, the second model-based OPC correction includes a standard model-based OPC correction and a process window model-based OPC correction.

[0027] In summary, the contact layer OPC method provided by the present application selects a feature OPC pattern in the contact layer target pattern, and selects a corresponding first sub-resolution assist pattern to obtain a second sub-resolution assist pattern, generates a third sub-resolution assist pattern with the edge of the feature target pattern corresponding to the feature OPC pattern as the target, and performs model-based OPC according to the target pattern and the third sub-resolution assist pattern to obtain a final OPC pattern. The contact layer OPC method provided by the present application can improve the overall process window as a whole, avoid the generation of OPC hotspots, and improve the process window of the hotspot via pattern by optimizing the sub-resolution assist pattern in the OPC processing flow, without the need to repeatedly perform the OPC flow, thereby reducing the OPC method optimization flow and OPC publishing time. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A flowchart of the contact layer OPC method provided by an embodiment of the present application;

[0029] Figures 2A to 2D A structure schematic diagram corresponding to each step of the contact layer OPC method provided by an embodiment of the present application;

[0030] Figure 3A An OPC pattern obtained by using a traditional contact layer OPC method;

[0031] Figure 3B An OPC pattern obtained by using the contact layer OPC method provided by the present application;

[0032] Figure 4A A simulation pattern obtained by using a traditional contact layer OPC method;

[0033] Figure 4B A simulation pattern obtained by using the contact layer OPC method provided by the present application.

[0034] Wherein, the reference signs are:

[0035] 100 - target pattern;

[0036] 110 - first OPC pattern;

[0037] 110a, 120a - feature OPC pattern;

[0038] 100a - feature target pattern;

[0039] 120 - second OPC pattern;

[0040] 210 - first sub-resolution assist pattern;

[0041] 220 - second sub-resolution assist pattern;

[0042] 230 - third sub-resolution assist pattern;

[0043] 210a - first sub-sub-resolution assist pattern;

[0044] 230a - second sub-sub-resolution assist pattern. DETAILED DESCRIPTION

[0045] In order to make the content of the present application more clear and easy to understand, the content of the present application is further explained below in combination with the drawings of the specification. Of course, the present application is not limited to this specific embodiment, and general substitutions well known to those skilled in the art are also covered within the protection scope of the present application.

[0046] Secondly, the present application is described in detail using a schematic diagram. In the detailed description of the examples of the present application, the schematic diagram is not enlarged in part according to the general proportion, and this should not be taken as a limitation of the present application.

[0047] For ease of description, some embodiments of the present application can use spatial relative terms such as "above", "below", "top", "bottom", etc. to describe the relationship between one element or component and another (or other) element or component as shown in the drawings of the embodiments. It should be understood that, in addition to the orientation described in the drawings, the spatial relative terms are also intended to include different orientations of the device in use or operation. For example, if the device in the drawings is turned over, the element or component described as "below" or "under" the other element or component will then be positioned "above" or "over" the other element or component. The terms "first", "second", etc. in the following are used to distinguish between similar elements, and are not necessarily used to describe a specific order or time sequence.

[0048] In the sub-resolution auxiliary pattern adding process, for the adding conflict area, a new sub-resolution auxiliary pattern can be formed by certain rules, usually this new sub-resolution auxiliary pattern mainly takes care of the via pattern with relatively small process window, so as to improve the overall process window. Since all the adding rules are based on the selected pattern structure, when a new pattern structure appears and the existing rules cannot cover it, it is easy to cause new OPC hot spot or defect.

[0049] For example, in the OPC correction process of the contact layer, if the simulation error of the via pattern in a certain direction (X direction or Y direction) is large, and the sub-resolution auxiliary pattern adding is not optimized, a large correction amount is needed to make the OPC result converge, so that the post-OPC simulation error meets the specification. Therefore, for the square contact layer via pattern, it will cause the OPC result to have a large aspect ratio, such as shown in FIG. 1B, and generally the process window of such large aspect ratio OPC pattern is small, which is easy to become an OPC hot spot. Figure 3A

[0050] In order to solve the above problems, the present application provides a contact layer OPC method, selecting a feature OPC pattern and selecting a corresponding first sub-resolution auxiliary pattern to obtain a second sub-resolution auxiliary pattern, generating a third sub-resolution auxiliary pattern with the feature target pattern edge corresponding to the feature OPC pattern as a target, performing model-based OPC according to the target pattern and the third sub-resolution auxiliary pattern to obtain a final OPC pattern. The contact layer OPC method provided by the present application can improve the overall process window as a whole, avoid the generation of OPC hot spot, and through the optimization of the sub-resolution auxiliary pattern in the OPC processing flow, improve the process window of the hot spot via pattern without the need to repeatedly perform the OPC flow, thereby reducing the OPC method optimization flow and OPC publishing time.

[0051] Figure 1 The flowchart of the contact layer OPC method provided by an embodiment of the present application is shown in FIG. 1A. As shown in FIG. 1A, the contact layer OPC method provided by the present embodiment comprises the following steps. Figure 1

[0052] Step S01: input the target pattern of the contact layer;

[0053] Step S02: generate the first sub-resolution auxiliary pattern according to the target pattern;

[0054] Step S03: perform the first model-based OPC correction according to the target pattern and the first sub-resolution auxiliary pattern to obtain the first OPC pattern;

[0055] Step S04: select the feature OPC pattern according to the first OPC pattern, and obtain the feature target pattern corresponding to the feature OPC pattern;

[0056] ​​Step S05: obtaining a second sub-resolution auxiliary pattern according to the feature OPC pattern and the feature target pattern;

[0057] Step S06: obtaining a third sub-resolution auxiliary pattern according to the feature target pattern and the second sub-resolution auxiliary pattern;

[0058] Step S07: performing a second model-based OPC correction according to the target pattern and the third sub-resolution auxiliary pattern to obtain a second OPC pattern.

[0059] Figures 2A to 2D The structure diagram corresponding to each step of the contact layer OPC method provided in the embodiment is shown in the following Figure 1 、 Figures 2A to 2D The contact layer OPC method provided in the embodiment is described in detail.

[0060] Specifically, first, as shown in Figure 2A , steps S01 and S02 are performed, the target pattern 100 of the contact layer is input, and the first sub-resolution auxiliary pattern 210 is generated according to the target pattern 100.

[0061] In the embodiment, the target pattern 100 of the contact layer is a square via pattern.

[0062] The first sub-resolution auxiliary pattern 210 is generated according to the target pattern 100, including:

[0063] According to the collected silicon wafer data of the sub-resolution auxiliary test pattern, a sub-resolution auxiliary pattern adding rule is established.

[0064] The sub-resolution auxiliary pattern adding rule includes a standard sub-resolution auxiliary pattern adding rule and a conflict pattern sub-resolution auxiliary pattern adding rule.

[0065] Next, continuing to refer to Figure 2A , steps S03 and S04 are performed, the first model-based OPC correction is performed according to the target pattern 100 and the first sub-resolution auxiliary pattern 210 to obtain the first OPC pattern 110, the feature OPC pattern 110a is selected according to the first OPC pattern 110, and the feature target pattern 100a corresponding to the feature OPC pattern 110a is obtained.

[0066] The first model-based OPC correction is an OPC correction based on a standard model established based on normal exposure conditions.

[0067] Select the target graphic 100 corresponding to the feature OPC graphic 110a to obtain the feature target graphic 100a, wherein the feature OPC graphic 110a is the first OPC graphic 110 with an aspect ratio greater than R after the target graphic 100 has undergone the first OPC correction based on the standard model, where 1.8 < R < 2.5, for example, R = 2.

[0068] Next, refer to Figure 2B and Figure 2C As shown, step S05 is executed to obtain the second sub-resolution auxiliary graphic 220 based on the feature OPC graphic 110a and the feature target graphic 100a.

[0069] Specifically, the second sub-resolution auxiliary graphic 220 obtained based on the feature OPC graphic 110a and the feature target graphic 100a includes:

[0070] Taking the side length B of the feature target graphic 100a as the starting side, extend outward along the vertical direction of the side length by an extension distance E to obtain the conflict check area C.

[0071] Filter the first sub-sub-resolution auxiliary graphic 210a that overlaps with or contacts the conflict check region C in the first sub-resolution auxiliary graphic 210;

[0072] Subtracting the first sub-sub-resolution auxiliary graphic 210a from the first sub-resolution auxiliary graphic 210 yields the second sub-resolution auxiliary graphic 220.

[0073] Wherein, the side length B extending along the feature target graphic 100a corresponds to the short side A of the feature OPC graphic 110a, such as Figure 2B As shown.

[0074] Furthermore, the expansion distance E extending outward from the side length B of the feature target graphic 100a is equal to the minimum distance from the first sub-resolution auxiliary graphic 210 to the target graphic 100 plus the minimum width of the first sub-resolution auxiliary graphic 210, that is, the sum of the minimum distance from the first sub-resolution auxiliary graphic 210 to the target graphic 100 and the minimum width of the first sub-resolution auxiliary graphic 210.

[0075] In this embodiment, the first sub-resolution auxiliary graphic 210 includes several first sub-sub-resolution auxiliary graphics 210a. These first sub-sub-resolution auxiliary graphics 210a are distributed at different positions with different sizes. After determining the conflict checking region C according to the above method, the first sub-sub-resolution auxiliary graphics 210a that overlap or contact the conflict checking region C will be deleted. That is, the first sub-sub-resolution auxiliary graphics 210a within region D will be deleted. The first sub-resolution auxiliary graphics 210 after deleting the first sub-sub-resolution auxiliary graphics 210a within region D constitutes the second sub-resolution auxiliary graphic 220. Figure 2C As shown.

[0076] Next, referring to Figure 2C and Figure 2D , steps S06 and S07 are performed to obtain a third sub-resolution assist feature 230 according to the feature target pattern 100a and the second sub-resolution assist feature 220, and to perform a second model-based OPC correction according to the target pattern 100 and the third sub-resolution assist feature 230 to obtain a second OPC pattern 120.

[0077] Specifically, the edge length of the feature target pattern 100a is taken as a target, and the second sub-resolution assist feature 220 is taken as a reference pattern, and the third sub-resolution assist feature 230 is generated according to a standard pattern sub-resolution assist feature addition rule.

[0078] Since the first sub-resolution assist feature 210 in the region D is deleted, the region D is empty, and the second sub-resolution assist feature 230a is generated in the region D in the third sub-resolution assist feature 230 generated according to the standard pattern sub-resolution assist feature addition rule, as shown in Figure 2D , so that the via pattern with a relatively small process window can be better taken care of, and the OPC hotspot can be avoided.

[0079] The second model-based OPC correction includes a standard model-based OPC correction and a process window model-based OPC correction.

[0080] Continuing to refer to Figure 2D , after the second model-based OPC correction according to the target pattern 100 and the third sub-resolution assist feature 230 is performed to obtain the second OPC pattern 120, the aspect ratio of the feature OPC pattern 120a corresponding to the feature target pattern 100a is reduced compared with the first OPC pattern 110 obtained by the first model-based OPC correction.

[0081] In another embodiment of the present application, the OPC pattern obtained by using a conventional contact layer OPC method is as shown in Figure 3A , the OPC pattern obtained by using the contact layer OPC method of the present application is as shown in Figure 3B , and Figure 3A and Figure 3B , it can be seen that the aspect ratio of the OPC pattern obtained by using the method provided by the present application is smaller, the via pattern with a relatively small process window can be taken care of, the overall process window is improved, and the OPC hotspot is avoided.

[0082] Further, the simulation pattern obtained by using the conventional contact layer OPC method is as shown in Figure 4A , the simulation pattern obtained by using the contact layer OPC method of the present application is as shown in Figure 4B , and Figure 4Aand Figure 4B As shown in the simulation results, the simulation error of the conventional contact layer OPC method is relatively large, about 1.3 nm, while the simulation error of the contact layer OPC method according to the present application is relatively small, about 0.4 nm.

[0083] In addition, the via layer OPC method according to the present application can improve the process window of the hot spot via pattern and does not need to repeat the OPC process, thereby significantly reducing the OPC method optimization process and OPC publishing time.

[0084] In summary, the present application provides a contact layer OPC method, which comprises: generating a first sub-resolution assist pattern according to a contact layer target pattern, performing a first model-based OPC correction to obtain a first OPC pattern, selecting a feature OPC pattern in the first OPC pattern and obtaining a feature target pattern corresponding to the feature OPC pattern, obtaining a second sub-resolution assist pattern according to the feature OPC pattern and the feature target pattern, then obtaining a third sub-resolution assist pattern according to the feature target pattern and the second sub-resolution assist pattern, and performing a second model-based OPC correction to obtain a second OPC pattern. The contact layer OPC method according to the present application can take care of the via pattern with a relatively small process window, improve the overall process window, and avoid the generation of OPC hot spots. Further, the present application can improve the process window of the hot spot via pattern and does not need to repeat the OPC process, thereby significantly reducing the OPC method optimization process and OPC publishing time.

[0085] The above description is only a description of the preferred embodiments of the present application and does not limit the scope of the present application in any way. Any modification or change made by a person skilled in the art according to the above disclosure is within the scope of protection of the claims.

Claims

1. A contact layer OPC method, characterized in that, include: Input the target graphic of the contact layer; Generate a first sub-resolution auxiliary graphic based on the target graphic; The first model-based OPC correction is performed based on the target graphic and the first sub-resolution auxiliary graphic to obtain the first OPC graphic; Based on the first OPC graphic, a feature OPC graphic is selected, and the corresponding feature target graphic is obtained. The feature OPC graphic is the first OPC graphic with an aspect ratio greater than R after the first model-based OPC correction of the target graphic, where 1.8 <R<2.5; Starting with one side of the feature target graphic as the starting edge, extend outward along the vertical direction of that edge by an extension distance to obtain the conflict detection area; Filter the first sub-sub-resolution auxiliary graphics that overlap or contact the conflict check region from the first sub-resolution auxiliary graphics; The second sub-sub-resolution auxiliary graphic is obtained by subtracting the first sub-sub-resolution auxiliary graphic from the first sub-resolution auxiliary graphic. Based on the feature target image and the second sub-resolution auxiliary image, the third sub-resolution auxiliary image is obtained; A second model-based OPC correction is performed based on the target graphic and the third sub-resolution auxiliary graphic to obtain the second OPC graphic.

2. The OPC method for the contact layer according to claim 1, characterized in that, The target pattern of the contact layer includes a square through-hole pattern.

3. The OPC method for the contact layer according to claim 1 or 2, characterized in that, Generating a first sub-resolution auxiliary graphic from the target graphic includes: Based on the collected silicon wafer data of sub-resolution auxiliary test patterns, rules for adding sub-resolution auxiliary patterns are established; The sub-resolution auxiliary graphics addition rules include: standard sub-resolution auxiliary graphics addition rules and conflicting graphics sub-resolution auxiliary graphics addition rules.

4. The OPC method for the contact layer according to claim 3, characterized in that, The first model-based OPC correction is an OPC correction performed based on a standard model established under normal exposure conditions.

5. The OPC method for the contact layer according to claim 1, characterized in that, The side length extended along the feature target graphic corresponds to the short side of the feature OPC graphic.

6. The OPC method for the contact layer according to claim 5, characterized in that, The extended distance is equal to the sum of the minimum distance from the first sub-resolution auxiliary graphic to the target graphic and the minimum width of the first sub-resolution auxiliary graphic.

7. The OPC method for the contact layer according to claim 6, characterized in that, Using the side length of the extended feature target graphic as the target and the second sub-resolution auxiliary graphic as the reference graphic, a third sub-resolution auxiliary graphic is generated according to the rules for adding sub-resolution auxiliary graphics of the standard graphic.

8. The OPC method for the contact layer according to claim 7, characterized in that, The second model-based OPC correction includes: OPC correction based on the standard model and OPC correction based on the process window model.

Images