OPC Method

Abstract

The present application discloses an OPC method, which includes: step 1: providing an initial target layer and setting a mask minimum resolution dimension; step 2: selecting a first pattern that will violate a mask rule check in subsequent MBOPC from the initial target layer; step 3: performing split processing on the first pattern to divide each side of the first pattern into a plurality of splits including corner splits and a middle split, the initial target layer after split processing being a second target layer; and step 4: performing MBOPC based on the second target layer and obtaining a mask pattern layer, the corner splits and the middle splits being corrected separately, the corner dimension of the first pattern in the mask pattern layer being controlled through the corner splits, the area of the first pattern in the mask pattern layer being controlled through the middle split.

Claims

1. An Optical Proximity Correction (OPC) method, comprising: step 1: providing an initial target layer and setting a mask minimum resolution dimension; step 2: selecting a first pattern that will violate a mask rule check in subsequent model-based OPC from the initial target layer according to the mask minimum resolution dimension; step 3: performing split processing on the first pattern, the split processing dividing each side of the first pattern into a plurality of splits, the splits of each side comprising corner splits and a middle split, one vertex of each corner split being a vertex of the side, the other vertex of each corner split being a vertex of an adjacent middle split, the initial target layer after split processing being a second target layer; and step 4: performing model-based OPC based on the second target layer and obtaining a mask pattern layer, the model-based OPC comprising several iterations, the corner splits and middle splits of each side of the first pattern being corrected separately in each iterative cyclic operation, a corner dimension of the first pattern in the mask pattern layer being controlled through the corner splits, an area of the first pattern in the mask pattern layer being controlled through the middle splits.

2. The OPC method according to claim 1, wherein, after step 4, the OPC method further comprises: step 5: performing the mask rule check on the mask pattern layer.

3. The OPC method according to claim 1, wherein, in step 1, the initial target layer is obtained through rule-based OPC of an initial layout.

4. The OPC method according to claim 2, wherein the mask minimum resolution dimension comprises a critical dimension minimum resolution value and a space minimum resolution value.

5. The OPC method according to claim 4, wherein, in step 5, when a critical dimension of the first pattern in the mask pattern layer is more than the critical dimension minimum resolution value and a space is more than the space minimum resolution value, the mask rule check passes.

6. The OPC method according to claim 4, wherein the first pattern comprises a square hole pattern.

7. The OPC method according to claim 6, wherein the square hole pattern comprises a via layer pattern.

8. The OPC method according to claim 7, wherein, in the initial target layer, an array structure formed through arrangement of each first pattern is a dense stagger pattern; and in the dense stagger pattern, diagonals of each first pattern are aligned and arranged periodically, a minimum space between the first patterns is equal to a distance between adjacent corners of two adjacent first patterns, and a pitch of the first patterns is equal to a sum of a length of the diagonal of the first pattern and the minimum space.

9. The OPC method according to claim 8, wherein the mask minimum resolution dimension is determined by a process node and mask manufacturing capacity.

10. The OPC method according to claim 9, wherein the critical dimension minimum resolution value and the space minimum resolution value are 18 nm or 12 nm at the same time.

11. The OPC method according to claim 10, wherein the minimum space between the first patterns is less than 20 nm, and the pitch of the first patterns is less than 115 nm.

12. The OPC method according to claim 10, wherein a target value of a side length of the first pattern is 68 nm and a dimension of the corner split in the split processing is 5-20 nm.

13. The OPC method according to claim 8, wherein, in step 3, the split processing divides each side of the first pattern into three splits, and the three splits comprise two corner splits and one middle split.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present application will be further described below in detail in combination with the specific embodiments with reference to the drawings.

[0036] FIG. 1 illustrates a flowchart of an existing OPC method.

[0037] FIG. 2A illustrates a schematic diagram of a pattern structure of a target layer in an existing OPC method.

[0038] FIG. 2B illustrates a schematic diagram of a pattern structure of a mask pattern layer formed by adopting an existing OPC method.

[0039] FIG. 3 illustrates a flowchart of an OPC method according to an embodiment of the present application.

[0040] FIG. 4A illustrates a schematic diagram of a pattern structure of an initial target layer in an OPC method according to an embodiment of the present application.

[0041] FIG. 4B illustrates a schematic diagram of a pattern structure of a second target layer in an OPC method according to an embodiment of the present application.

[0042] FIG. 4C illustrates a schematic diagram of a pattern structure of a mask pattern layer in an OPC method according to an embodiment of the present application.

[0043] FIG. 4D illustrates a schematic diagram of a contour formed through exposed pattern simulation by adopting the mask pattern layer in FIG. 4C.

[0044] FIG. 5A illustrates a simulation pattern of a mask pattern layer and a contour formed by adopting an existing OPC method.

[0045] FIG. 5B illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 5 nm in an OPC method according to an embodiment of the present application.

[0046] FIG. 5C illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 10 nm in an OPC method according to an embodiment of the present application.

[0047] FIG. 5D illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 15 nm in an OPC method according to an embodiment of the present application.

[0048] FIG. 5E illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 20 nm in an OPC method according to an embodiment of the present application.

DETAILED DESCRIPTION

[0049] Referring to FIG. 3, it illustrates a flowchart of an OPC method according to an embodiment of the present application. Referring to FIG. 4A, it illustrates a schematic diagram of a pattern structure of an initial target layer 301 in an OPC method according to an embodiment of the present application. Referring to FIG. 4B, it illustrates a schematic diagram of a pattern structure of a second target layer 301a in an OPC method according to an embodiment of the present application. Referring to FIG. 4C, it illustrates a schematic diagram of a pattern structure of a mask pattern layer 304 in an OPC method according to an embodiment of the present application. Referring to FIG. 4D, it illustrates a schematic diagram of a contour formed through exposed pattern simulation by adopting the mask pattern layer 304 in FIG. 4C. The OPC method provided by the present application includes the following steps:

[0050] In step 1, referring to FIG. 4A, an initial target layer 301 is provided and a mask minimum resolution dimension is set.

[0051] In the embodiment of the present application, the initial target layer 301 is obtained through rule-based OPC of an initial layout.

[0052] The mask minimum resolution dimension includes a critical dimension minimum resolution value and a space minimum resolution value.

[0053] The mask minimum resolution dimension is determined by a process node and mask manufacturing capacity.

[0054] In some embodiments, and the critical dimension minimum resolution value and the space minimum resolution value are 18 nm or 12 nm at the same time.

[0055] In step 2, a first pattern 302 that will violate a mask rule check in subsequent model-based OPC is selected from the initial target layer 301 according to the mask minimum resolution dimension. FIG. 4A shows only the first pattern 302 in the initial target layer 301. The initial target layer 301 also includes other types of patterns, which are not illustrated in FIG. 4A.

[0056] In the embodiment of the present application, the first pattern 302 includes a square hole pattern.

[0057] In some preferred embodiments, the square hole pattern includes a via layer pattern.

[0058] In the initial target layer 301, an array structure formed through arrangement of each first pattern 302 is a dense stagger pattern; in the dense stagger pattern, diagonals of each first pattern 302 are aligned and arranged periodically, the minimum space between the first patterns 302 is equal to a distance between adjacent corners of two adjacent first patterns 302, and the pitch of the first patterns 302 is equal to a sum of the length of the diagonal of the first pattern 302 and the minimum space.

[0059] In some embodiments, the minimum space between the first patterns 302 is less than 20 nm and the pitch of the first patterns 302 is less than 115 nm.

[0060] In step 3, referring to FIG. 4B, split processing is performed on the first pattern 302. The split processing divides each side of the first pattern 302 into a plurality of splits. The splits of each side include corner splits 303a and middle splits 303b. One vertex of each corner split 303a is a vertex of the side. The other vertex of each corner split 303a is a vertex of the adjacent middle splits 303b. The broken line between the corner split 303a and the middle splits 303b in FIG. 4B is only used for visually distinguishing the corner split 303a and the middle splits 303b. In fact, the corner split 303a and the middle splits 303b are connected together.

[0061] The initial target layer 301a after split processing is a second target layer 301a.

[0062] In the embodiment of the present application, the split processing divides each side of the first pattern 302 into three splits, and the three splits includes two corner splits 303a and one middle split 303b.

[0063] In some embodiment, a target value of the side length of the first pattern 302 is 68 nm and the dimension of the corner split 303a in the split processing is 5-20 nm.

[0064] In step 4, referring to FIG. 4C, model-based OPC is performed based on the second target layer 301a and a mask pattern layer 304 is obtained. The model-based OPC includes a plurality of iterative cyclic operations. The corner splits 303a and the middle split 303b of each side of the first pattern 302 are corrected separately in each iterative cyclic operation. The corner dimension of the first pattern 305 in the mask pattern layer 304 is controlled through the corner splits 303a. The area of the first pattern 305 in the mask pattern layer 304 is controlled through the middle splits 303b. In FIG. 4C, the first pattern is separately represented by reference sign 305. The first pattern 305 in FIG. 4C is formed by the first pattern 302 in FIG. 4A after MBOPC. It can be seen from FIG. 4C that the separate correction of the corner splits 303a and the middle split 303b of each side of the first pattern 302 can avoid that each side of the first pattern 302 needs to be moved as a whole in the process of MBOPC in the existing method, so that it can be moved in splits. In this way, the movement amount of the side of the first pattern 302 at the corner splits 303a is different from the movement amount at the middle splits 303b. By comparing with the first pattern 302 in the initial target layer 301 in FIG. 4A, it can be seen that the side of the first pattern 305 in FIG. 4C after MBOPC is no longer flat, a convex pattern 305a is formed at the corresponding position of the middle splits 303b, and the convex pattern 305a will increase the area of the first pattern 305.

[0065] In step 5, the mask rule check is performed on the mask pattern layer 304.

[0066] In step 5, when the critical dimension of the first pattern 305 in the mask pattern layer 304 is more than the critical dimension minimum resolution value and the space is more than the space minimum resolution value, the mask rule checks passes.

[0067] Referring to FIG. 4C, the critical dimension of the first pattern 305 is the minimum width, and the space between the first patterns 305 is corner-to-corner space d302.

[0068] The mask rule check will be inserted into each iteration of model-based OPC. Even when the corner-to-corner space d302 is close to the space minimum resolution value, the side at the middle splits 303b can still be corrected, that is, moved, thus avoiding the defect that the entire side cannot be moved when the corner-to-corner space d302 is close to the space minimum resolution value in the existing method. The side movement at the middle splits 303b can increase the area of the first pattern 305, so the embodiment of the present application can increase the area of the first pattern 305 under the condition that the corner-to-corner space d302 does not violate MRC.

[0069] The increase of the area of the first pattern 305 can increase the area of the corresponding exposed pattern, so that the exposed pattern conforms to the target value, that is, on-target. As illustrated in FIG. 4D, the contour 306 is a schematic diagram of the simulation pattern of the exposed pattern corresponding to the first pattern 305. Compared with the contour 205 of FIG. 2B, the contour 306 obtained in the embodiment of the present application has a larger area and is closer to the corresponding target pattern, thus eliminating the off-target defect corresponding to FIG. 2B.

[0070] However, in the prior art, since the sides of the first pattern 302 are not subjected to split processing before MBOPC, when the corner-to-corner space between the first patterns 302 is restricted from violating MRC in MBOPC and the iteration is stopped, the area of the first pattern 302 will remain small, and finally the contour of the first pattern 302 after MBOPC, that is, the simulation pattern of the exposed pattern, will be off target. After providing the initial target layer 301 in the embodiment of the present application, model-based OPC is not directly performed based on the initial target layer 301, but the first pattern 302 that will violate MRC in model-based OPC is selected according to the characteristics of the patterns in the initial target layer 301. After that, split processing is performed on the selected patterns the second target layer 301a is formed. Then, MBOPC is performed. After each side of the first pattern 302 is subjected to split processing, the corner splits 303a and the middle splits 303b can be corrected separately in each iterative cyclic operation of MBOPC, so that the corner dimension of the first pattern 302 and the dimension of the middle area can be adjusted separately. By adjusting the corner dimension of the first pattern 302, the corner-to-corner space between the first patterns 302 does not violate MRC. By adjusting the dimension of the middle area, the area of the first pattern 302 can be adjusted, so that the area of the first pattern 302 can be increased when the corner-to-corner space between the first patterns 302 meets the requirements of MRC. The increase of the area of the first pattern 302 after MBOPC can make the contour be on target, so that the pattern after actual exposure will also be on target.

[0071] The present application is particularly applicable to the OPC of square patterns in a dense stagger pattern, such as the via layer pattern, and can realize the dimension of the square patterns on the mask pattern layer 304. Under the condition of not violating the MRC, not only the simulation contour of the exposed pattern is on target, but also the pvband and meef under the PW meet the requirements of mass production.

[0072] Referring to FIG. 5A, it illustrates a simulation pattern of a mask pattern layer and a contour formed by adopting an existing OPC method. A mask pattern layer 401a includes a mask pattern 403a for performing MBOPC on a target pattern 402. The target pattern 402 corresponds to the pattern 202 in FIG. 2A, and the mask pattern 403a corresponds to the pattern 204 in FIG. 2B. The existing method is also equivalent to that the dimension of the corner split described in the embodiment method of the present application is 0 nm, i.e., Split 0 nm. A contour 404a is a simulation pattern of the exposed pattern corresponding to the mask pattern 403a. It can be seen that the contour 404a is greatly different from the target pattern 402 and is in an off-target state.

[0073] FIG. 5B illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 5 nm in an OPC method according to an embodiment of the present application. A mask pattern layer 401b includes a mask pattern 403b for performing MBOPC on a target pattern 402. The target pattern 402 corresponds to the pattern 302 in FIG. 4A, which is the same as the target pattern 402 in FIG. 5A. That is, different MBOPC operations are performed on the corresponding target patterns 402 to compare the correction results. A contour 404b is a simulation pattern of the exposed pattern corresponding to the mask pattern 403b. The dimension of the corner split in FIG. 5B is 5 nm, i.e., Split 5 nm. It can be seen that the contour 404b is close to the target pattern 402 and is in an on-target state.

[0074] FIG. 5C illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 10 nm in an OPC method according to an embodiment of the present application. A mask pattern layer 401c includes a mask pattern 403c for performing MBOPC on a target pattern 402. The target pattern 402 corresponds to the pattern 302 in FIG. 4A. A contour 404c is a simulation pattern of the exposed pattern corresponding to the mask pattern 403c. The dimension of the corner split in FIG. 5C is 10 nm, i.e., Split 10 nm. It can be seen that the contour 404c is close to the target pattern 402 and is in an on-target state.

[0075] FIG. 5D illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 15 nm in an OPC method according to an embodiment of the present application. A mask pattern layer 401d includes a mask pattern 403d for performing MBOPC on a target pattern 402. The target pattern 402 corresponds to the pattern 302 in FIG. 4A. A contour 404d is a simulation pattern of the exposed pattern corresponding to the mask pattern 403d. The dimension of the corner split in FIG. 5D is 15 nm, i.e., Split 15 nm. It can be seen that the contour 404d is close to the target pattern 402 and is in an on-target state.

[0076] FIG. 5E illustrates a simulation pattern of a mask pattern layer and a contour formed when a corner split dimension is 20 nm in an OPC method according to an embodiment of the present application. A mask pattern layer 401e includes a mask pattern 403e for performing MBOPC on a target pattern 402. The target pattern 402 corresponds to the pattern 302 in FIG. 4A. A contour 404e is a simulation pattern of the exposed pattern corresponding to the mask pattern 403e. The dimension of the corner split in FIG. 5E is 20 nm, i.e., Split 20 nm. It can be seen that the contour 404e is close to the target pattern 402 and is in an on-target state.

[0077] Test data corresponding to FIG. 5A to FIG. 5E are as shown in Table 1.

TABLE-US-00001 TABLE 1 Existing Method Split processing Results 0 nm 5 nm 10 nm 15 nm 20 nm Target/nm 67 67 67 67 67 Mask Space/nm 12.02 12.02 12.02 12.02 12.02 Mask CD/nm 70*69.1 71.4*71.5 71.7*71.9 73*73.2 74.3*74.4 Mask Area/nm2 4837 5117 5177 5129 5122 Contour/nm 57.2 67.1 67.1 66.9 67 PW_minCD/nm 51.1 62.7 62.6 62.6 62.6 Pvband/nm 5.4 3.9 3.9 3.9 3.9 Meef 6.1 4.6 4.6 4.8 4.9

[0078] The split dimension corresponding to the existing method, i.e., the dimension of the corner split, is 0 nm. The split processing is listed according to different split dimensions, i.e., 5 nm, 10 nm, 15 nm and 20 nm.

[0079] In the test results, Target represents the critical dimension of the target pattern 402;

[0080] Mask Space represents the space between the mask patterns;

[0081] Mask CD represents the critical dimension of the mask patterns;

[0082] Mask Area represents the area of the mask patterns;

[0083] Contour represents the critical dimension of the contour;

[0084] PW_minCD represents the minimum critical dimension of the process window.

[0085] Pvband represents the process variation band.

[0086] Meef represents the mask error enhancement factor.

[0087] It can be seen that under the condition that Mask Space does not violate MRC, the corresponding Mask CD, Mask Area and critical dimension of Contour in the embodiment of the present application will increase, the PW_minCD will increase, the Pvband will decrease and the Meef will decrease, all of which indicate that the OPC results of the method according to the embodiment of the present application are better.

[0088] The present application has been described in detail through the specific embodiments above, which, however, do not constitute limitations to the present application. Without departing from the principle of the present application, those skilled in the art may make many changes and improvements, which should also be considered as included in the scope of protection of the present application.