Optical proximity correction method

Abstract

An optical proximity correction method comprises: providing an initial design layout, the initial design layout having a reference pattern and a plurality of main patterns, the reference pattern having a reference edge, and each main pattern having a plurality of main edges; taking each main edge as a reference, obtaining a first search parameter to determine a first search region; when the reference edge has an overlapping part with any one of the first search regions, marking the main edge corresponding to the first search region as a candidate edge; taking the reference edge as a reference, obtaining a second search parameter according to the first search parameter to determine a second search region; and when any one of the candidate edges has an overlapping part with the second search region, marking the candidate edge as a selected edge. The bidirectional edge selection mechanism of the first search region and the second search region is used for edge selection operation, the cases of multiple selection or misselection are reduced, the edge selection result is more accurate, and the effect of subsequent optical proximity correction is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to an optical proximity correction method. Background Technology

[0002] Photolithography is a crucial technology in semiconductor manufacturing. It transfers patterns from a photomask to the surface of a silicon wafer, forming semiconductor products that meet design requirements. The photolithography process includes an exposure step, a development step following exposure, and an etching step following development. In the exposure step, light passes through the light-transmitting areas of the photomask and shines onto the silicon wafer coated with photoresist, causing a chemical reaction in the photoresist. In the development step, the different solubility of the developer in the photoresist and the non-photoresist is used to form a photolithographic pattern, transferring the photomask pattern onto the photoresist. In the etching step, the silicon wafer is etched based on the photolithographic pattern formed by the photoresist layer, further transferring the photomask pattern onto the silicon wafer.

[0003] In semiconductor manufacturing, as design dimensions continue to shrink and approach the limits of photolithography imaging systems, the diffraction effect of light becomes increasingly pronounced, leading to optical image degradation of the final design pattern. The actual photolithographic pattern formed is severely distorted relative to the pattern on the mask, resulting in a difference between the actual pattern formed on the silicon wafer and the design pattern. This phenomenon is called the Optical Proximity Effect (OPE).

[0004] To correct the optical proximity effect, Optical Proximity Correction (OPC) was developed. The core idea of ​​OPC is to establish an OPC model based on the consideration of counteracting the optical proximity effect. The photomask pattern is designed according to the OPC model. In this way, although the lithographic pattern and the corresponding photomask pattern have an optical proximity effect, the cancellation of this phenomenon has been considered when designing the photomask pattern according to the OPC model. Therefore, the lithographic pattern after photolithography is close to the target pattern actually desired by the user.

[0005] Currently, in the process of optical proximity correction, the edges of the pattern need to be readjusted according to the etch bias table for different environments. Therefore, the selection of the pattern edges is particularly important in the process of optical proximity correction.

[0006] However, existing technologies still have many problems in the edge selection operation of optical proximity correction. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide an optical proximity correction method to reduce the occurrence of over-selection or misselection during the edge selection process of optical proximity correction.

[0008] To solve the above-mentioned technical problems, the present invention provides an optical proximity correction method, comprising: providing an initial design layout, wherein the initial design layout has a reference graphic and several main graphics, the reference graphic having a reference edge, and each main graphic having several main edges; obtaining a first search parameter based on each main edge to determine a first search region; when the reference edge overlaps with any of the first search regions, marking the main edge corresponding to the first search region as a candidate edge; obtaining a second search parameter based on the reference edge and according to the first search parameter to determine a second search region; when any of the candidate edges overlaps with the second search region, i.e., when the reference edge and the candidate edge are mutually selected by the first search region and the second search region, marking the candidate edge as a selected edge.

[0009] Optionally, the positional relationship between the reference edge and the candidate edge includes: the reference edge is parallel to all the candidate edges, or the angle between the reference edge and at least one candidate edge is an acute angle α.

[0010] Optionally, the first search parameters include: a first inward value M_in, a first outward value M_out, a first start value M_start, and a first end value M_end, wherein: the first inward value M_in is the distance between the main edge and the edge of the first search region, oriented towards the main graphic and perpendicular to the main edge; the first outward value M_out is the distance between the main edge and the edge of the first search region, oriented towards the direction away from the main graphic and perpendicular to the main edge; the first start value M_start is the distance between the first endpoint of the main edge and the edge of the first search region, oriented towards the direction away from the main graphic and parallel to the main edge; the first end value M_end is the distance between the second endpoint of the main edge and the edge of the first search region, oriented towards the direction away from the main graphic and parallel to the main edge; wherein the first endpoint and the second endpoint are two opposite endpoints of the main edge.

[0011] Optionally, the first search area is a rectangle.

[0012] Optionally, the second search parameters include: a second inward value R_in, a second outward value R_out, a second start value R_start, and a second end value R_end, wherein: the second inward value R_in is the distance between the reference edge and the edge of the second search region, oriented towards the direction close to the reference graphic and perpendicular to the reference edge; the second outward value R_out is the distance between the reference edge and the edge of the second search region, oriented towards the direction away from the reference graphic and perpendicular to the reference edge; the second start value R_start is the distance between the third endpoint of the reference edge and the edge of the second search region, oriented towards the direction away from the reference graphic and parallel to the reference edge; the second end value R_end is the distance between the fourth endpoint of the reference edge and the edge of the second search region, oriented towards the direction away from the reference graphic and parallel to the reference edge; wherein the third endpoint and the fourth endpoint are two opposite endpoints of the reference edge.

[0013] Optionally, the second search area is a rectangle.

[0014] Optionally, when the reference edge is parallel to all the candidate edges, the method for obtaining the second search parameter based on the first search parameter includes: obtaining the second inward value R_in = M_in based on the first inward value M_in; obtaining the second outward value R_out = M_out based on the first outward value M_out; obtaining the second start value R_start = M_start based on the first start value M_start; and obtaining the second end value R_end = M_end based on the first end value M_end.

[0015] Optionally, when the angle between the reference edge and at least one of the candidate edges is an acute angle α, the method for obtaining the second search parameter based on the first search parameter includes: obtaining the second inward value R_in = M_in based on the first inward value M_in; obtaining the second outward value R_out = max(M_start, M_end)*sinα based on the first start value M_start, the first end value M_end, and the acute angle α; obtaining the second start value R_start = M_out / sinα based on the first outward value M_out and the acute angle α; and obtaining the second end value R_end = M_out / sinα based on the first outward value M_out and the acute angle α.

[0016] Optionally, after marking the candidate edge as the selected edge, the method further includes: moving the selected edge according to the etching deviation table, so that the corresponding main graphic forms an adjustment graphic, and so that the initial design layout forms a design layout.

[0017] Optionally, after the main graphic forms the adjusted graphic, the process further includes: performing several iterations of optical proximity correction on the design layout.

[0018] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0019] The optical proximity correction method provided by the present invention performs edge selection through a bidirectional edge selection mechanism of the first search region and the second search region. Only when the reference edge and the edge to be selected have been mutually selected by the first search region and the second search region is the edge to be selected marked as the selected edge. This edge selection mechanism can effectively eliminate interfering edges, thereby reducing the possibility of over-selection or misselection, making the edge selection result more accurate, and thus improving the effect of subsequent optical proximity correction.

[0020] Furthermore, after marking the candidate edge as the selected edge, the process further includes: moving the selected edge according to the etching bias table, so that the corresponding main pattern forms an adjusted pattern, and so that the initial design layout forms a design layout. This preliminary processing of the main pattern based on the etching bias table before optical proximity correction can reduce the number of iterations in subsequent optical proximity corrections and improve process efficiency. Attached Figure Description

[0021] Figure 1 A schematic diagram of the edge selection process in an optical proximity correction method;

[0022] Figure 2 This is a flowchart of the optical proximity correction method according to an embodiment of the present invention;

[0023] Figures 3 to 8 This is a schematic diagram of the specific process of the optical proximity correction method according to an embodiment of the present invention.

[0024] Figure 9 This is a schematic diagram of the specific steps of the optical proximity correction method according to another embodiment of the present invention. Detailed Implementation

[0025] As described in the background section, existing technologies still have many problems in the edge selection operation of optical proximity correction. These will be explained in detail below with reference to the accompanying drawings.

[0026] Figure 1 A schematic diagram of the edge selection process in an optical proximity correction method.

[0027] Please refer to Figure 1An initial design layout 100 is provided, which includes a reference graphic 101 and several main graphics 102. The reference graphic 101 has a reference edge 101a, and each of the main graphics 102 has several main edges 102a. Based on each main edge 102a, search parameters are obtained to determine a search region S. When the reference edge 101a overlaps with any of the search regions S, the main edge 102a corresponding to the search region S is marked as a selected edge 103.

[0028] In this embodiment, the search area S is determined based on an internal query box algorithm. The search area S is then used to find the relationships between edges, thereby achieving edge selection. The search parameters include: inward value (in), outward value (out), start value (start), and end value (end). The inward value (in) is the distance from the main edge 102a towards the main graphic 102; the outward value (out) is the distance from the main edge 102a away from the main graphic 102; the start value (start) is the distance from the first endpoint O1 of the main edge 102a away from the main graphic 102; and the end value (end) is the distance from the second endpoint O2 of the main edge 102a opposite to the first endpoint O1 away from the main graphic 102. The final determined search area S is a rectangle.

[0029] It should be noted that, Figure 1 Only the search area S corresponding to the selected edge 103 is shown in the image.

[0030] However, when performing edge selection operations using the defined search area S, multiple selected edges are often determined simultaneously. According to the etch bias table, in cases where the search area S needs to pass through the main pattern 102 to reach the main edge 102a (such as...), the selected edges are often... Figure 1 As shown in Part A, these areas do not need to be selected. The search area S cannot be clearly distinguished in this situation, easily leading to multiple selections or incorrect selections.

[0031] To address the aforementioned technical problems, the present invention provides an optical proximity correction method. This method employs a bidirectional edge selection mechanism between a first search region and a second search region. Only when the reference edge and the edge to be selected have been mutually selected by both the first and second search regions is the edge to be selected marked as the selected edge. This edge selection mechanism effectively eliminates interfering edges, thereby reducing over-selection or misselection, resulting in more accurate edge selection and improved subsequent optical proximity correction.

[0032] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] Figure 2 This is a flowchart of an optical proximity correction method according to an embodiment of the present invention, including:

[0034] Step S101: Provide an initial design layout, which has a reference graphic and several main graphics. The reference graphic has reference edges, and each main graphic has several main edges.

[0035] Step S102: Based on each of the main edges, obtain the first search parameters to determine the first search area;

[0036] Step S103: When the reference edge overlaps with any of the first search regions, the main edge corresponding to the first search region is marked as a candidate edge;

[0037] Step S104: Using the reference edge as a reference, obtain the second search parameters according to the first search parameters to determine the second search area;

[0038] Step S105: When any one of the candidate edges overlaps with the second search area, that is, when the reference edge and the candidate edge are mutually selected by the first search area and the second search area, the candidate edge is marked as the selected edge.

[0039] The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.

[0040] Figures 3 to 8 This is a schematic diagram of the specific steps of the optical proximity correction method according to an embodiment of the present invention.

[0041] Please refer to Figure 3 An initial design layout 200 is provided, which includes a reference graphic 201 and several main graphics 202. The reference graphic 201 has a reference edge 201a, and each of the main graphics 202 has several main edges 202a.

[0042] It should be noted that, in this embodiment, the several main graphics 202 are graphics corresponding to the fabrication of each device structure in the current layer, and the reference figure 201 can be a graphic corresponding to the fabrication of the device structure in the current layer or a graphic corresponding to the fabrication of device structures in other layers.

[0043] It should be noted that, in this embodiment, the main edges 202a of the main graphic 202 are specifically: the edges that surround and form the main graphic 202.

[0044] Please refer to Figure 4 Based on each of the main edges 202a, first search parameters are obtained to determine the first search region S1.

[0045] In this embodiment, the first search parameters include: a first inward value M_in, a first outward value M_out, a first start value M_start, and a first end value M_end, wherein: the first inward value M_in is the direction toward the main graphic 202 and perpendicular to the main edge 202a, and the distance between the main edge 202a and the edge of the first search region S1; the first outward value M_out is the direction away from the main graphic 202 and perpendicular to the main edge 202a, and the distance between the main edge 202a and the edge of the first search region S1. The distance between the edges; the first start value M_start is the distance between the first endpoint O1 of the main edge 202a and the edge of the first search region S1, in a direction that is away from the main graphic 202 and parallel to the main edge 202a; the first end value M_end is the distance between the second endpoint O2 of the main edge 202a and the edge of the first search region S1, in a direction that is away from the main graphic 202 and parallel to the main edge 202a; wherein, the first endpoint O1 and the second endpoint O2 are two opposite endpoints of the main edge 202a.

[0046] In this embodiment, the first search area S1 is a rectangle.

[0047] Please refer to Figure 5 When the reference edge 201a overlaps with any of the first search regions S1, the main edge 202a corresponding to the first search region S1 is marked as a candidate edge.

[0048] It should be noted that, in this embodiment, Figure 5 Only the first search region S1 corresponding to the edge to be selected is shown in the figure. Figure 5 The first candidate edge 203a and the second candidate edge 203b in the equation.

[0049] In this embodiment, the positional relationship between the reference edge 201a and the candidate edges is as follows: the reference edge 201a is parallel to all the candidate edges, that is... Figure 5 The reference edge 201a is parallel to the first candidate edge 203a, and the reference edge 201a is parallel to the second candidate edge 203b.

[0050] Please refer to Figure 6 Using the reference edge 201a as a reference, the second search parameters are obtained according to the first search parameters to determine the second search region S2.

[0051] In this embodiment, the second search parameters include: a second inward value R_in, a second outward value R_out, a second start value R_start, and a second end value R_end, wherein: the second inward value R_in is the direction toward the reference pattern 201 and perpendicular to the reference edge 201a, and the distance between the reference edge 201a and the edge of the second search region S2; the second outward value R_out is the direction away from the reference pattern 201 and perpendicular to the reference edge 201a, and the distance between the reference edge 201a and the edge of the second search region S2. The distance from the edge; the second start value R_start is the distance from the third endpoint O3 of the reference edge 201a to the edge of the second search area S2, in a direction that is away from the reference graphic 201 and parallel to the reference edge 201a; the second end value R_end is the distance from the fourth endpoint O4 of the reference edge 201a to the edge of the second search area S2, in a direction that is away from the reference graphic 201 and parallel to the reference edge 201a; wherein, the third endpoint O3 and the fourth endpoint O4 are two opposite endpoints of the reference edge 201.

[0052] In this embodiment, the second search area S2 is a rectangle.

[0053] In this embodiment, the reference edge 201a is parallel to all the candidate edges. The method for obtaining the second search parameter based on the first search parameter is as follows: based on the first inward value M_in, obtain the second inward value R_in = M_in; based on the first outward value M_out, obtain the second outward value R_out = M_out; based on the first start value M_start, obtain the second start value R_start = M_start; based on the first end value M_end, obtain the second end value R_end = M_end.

[0054] Please refer to Figure 7When any of the candidate edges overlaps with the second search area S2, that is, when the reference edge 201a and the candidate edge are mutually selected by the first search area S1 and the second search area S2, the candidate edge is marked as the selected edge 204.

[0055] It should be noted that, in this embodiment, Figure 7 The first candidate edge 203a and the second search area S2 have an overlapping portion, so the first candidate edge 203a is marked as the selected edge 204. However, the second candidate edge 203b does not have an overlapping portion with the second search area S2, so the second candidate edge 203b is not marked as the selected edge 204.

[0056] In this embodiment, edge selection is performed through a bidirectional edge selection mechanism using the first search region S1 and the second search region S2. Only when the reference edge 201a and the edge to be selected have been mutually selected by both the first search region S1 and the second search region S2 is the edge to be selected marked as the selected edge. This edge selection mechanism effectively eliminates interfering edges to be selected, thereby reducing the possibility of over-selection or misselection, resulting in more accurate edge selection and improving the effect of subsequent optical proximity correction.

[0057] Please refer to Figure 8 After marking the candidate edge as the selected edge 204, the selected edge is moved according to the etching deviation table, so that the corresponding main pattern 202 forms the adjustment pattern 205 and the initial design layout 200 forms the design layout 300.

[0058] In this embodiment, the preliminary processing of the main pattern 202 before optical proximity correction based on the etch bias table can reduce the number of iterations of subsequent optical proximity correction and improve process efficiency.

[0059] Please continue to refer to this. Figure 8 After the main graphic 202 forms the adjusted graphic 205, the design layout 300 undergoes several iterations of optical proximity correction.

[0060] Figure 9 This is a schematic diagram of the specific steps of the optical proximity correction method according to another embodiment of the present invention.

[0061] This embodiment further illustrates the optical proximity correction method based on the above embodiments. The difference between this embodiment and the above embodiments is that the angle between the reference edge 201a and at least one of the candidate edges is an acute angle α. Please refer to [link / reference] for details. Figure 9 .

[0062] Please refer to Figure 9 The angle between the reference edge 201a and at least one of the candidate edges is an acute angle α.

[0063] It should be noted that, in this embodiment, Figure 9 The diagram shows that the angle between the reference edge 201a and the first candidate edge 203a is an acute angle α, and the reference edge 201a is parallel to the second candidate edge 203b.

[0064] In this embodiment, the angle between the reference edge 201a and at least one of the candidate edges is an acute angle α. The method for obtaining the second search parameter based on the first search parameter includes: obtaining the second inward value R_in = M_in based on the first inward value M_in; obtaining the second outward value R_out = max(M_start, M_end)*sinα based on the first start value M_start, the first end value M_end, and the acute angle α; obtaining the second start value R_start = M_out / sinα based on the first outward value M_out and the acute angle α; and obtaining the second end value R_end = M_out / sinα based on the first outward value M_out and the acute angle α.

[0065] Please continue to refer to this. Figure 9 In this embodiment, Figure 9 The first candidate edge 203a and the second search area S2 have an overlapping portion, so the first candidate edge 203a is marked as the selected edge 204. However, the second candidate edge 203b does not have an overlapping portion with the second search area S2, so the second candidate edge 203b is not marked as the selected edge 204.

[0066] In this embodiment, edge selection is performed through a bidirectional edge selection mechanism using the first search region S1 and the second search region S2. Only when the reference edge 201a and the edge to be selected have been mutually selected by both the first search region S1 and the second search region S2 is the edge to be selected marked as the selected edge. This edge selection mechanism effectively eliminates interfering edges to be selected, thereby reducing the possibility of over-selection or misselection, resulting in more accurate edge selection and improving the effect of subsequent optical proximity correction.

[0067] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An optical proximity correction method, characterized in that, include: An initial design layout is provided, which includes a reference graphic and several main graphics. The reference graphic has reference edges, and each of the main graphics has several main edges. Based on each of the principal edges, first search parameters are obtained to determine the first search region; When the reference edge overlaps with any of the first search regions, the main edge corresponding to the first search region is marked as a candidate edge; Using the reference edge as a reference, the second search parameters are obtained according to the first search parameters to determine the second search area; When any of the candidate edges overlaps with the second search area, that is, when the reference edge and the candidate edge are mutually selected by the first search area and the second search area, the candidate edge is marked as the selected edge.

2. The optical proximity correction method as described in claim 1, characterized in that, The positional relationship between the reference edge and the candidate edge includes: the reference edge is parallel to all the candidate edges, or the angle between the reference edge and at least one candidate edge is an acute angle α.

3. The optical proximity correction method as described in claim 2, characterized in that, The first search parameters include: a first inward value M_in, a first outward value M_out, a first start value M_start, and a first end value M_end, wherein: The first inward value M_in is the direction toward the main graphic and perpendicular to the main edge, and the distance between the main edge and the edge of the first search region; The first outward value M_out is the direction toward the main graphic and perpendicular to the main edge, and the distance between the main edge and the edge of the first search region; The first starting value M_start is the direction that is away from the main graphic and parallel to the main edge, and the distance between the first endpoint of the main edge and the edge of the first search region; The first end value M_end is the distance between the second endpoint of the main edge and the edge of the first search region, which is the direction away from the main graphic and parallel to the main edge; Wherein, the first endpoint and the second endpoint are the two opposite endpoints of the main edge.

4. The optical proximity correction method as described in claim 3, characterized in that, The first search area is a rectangle.

5. The optical proximity correction method as described in claim 4, characterized in that, The second search parameters include: a second inward value R_in, a second outward value R_out, a second start value R_start, and a second end value R_end, wherein: The second inward value R_in is the direction toward the reference graphic and perpendicular to the reference edge, and the distance between the reference edge and the edge of the second search region; The second outward value R_out is the direction that is away from the reference graphic and perpendicular to the reference edge, and the distance between the reference edge and the edge of the second search region; The second start value R_start is the direction that is away from the reference graphic and parallel to the reference edge, and the distance between the third endpoint of the reference edge and the edge of the second search region; The second end value R_end is the direction that is away from the reference graphic and parallel to the reference edge, and the distance between the fourth endpoint of the reference edge and the edge of the second search area; The third endpoint and the fourth endpoint are two opposite endpoints of the reference edge.

6. The optical proximity correction method as described in claim 5, characterized in that, The second search area is a rectangle.

7. The optical proximity correction method as described in claim 6, characterized in that, When the reference edge is parallel to all the candidate edges, the method for obtaining the second search parameter based on the first search parameter includes: Based on the first inward value M_in, obtain the second inward value R_in = M_in; Based on the first outgoing value M_out, obtain the second outgoing value R_out = M_out; Based on the first start value M_start, obtain the second start value R_start = M_start; Based on the first end value M_end, obtain the second end value R_end = M_end.

8. The optical proximity correction method as described in claim 6, characterized in that, When the angle between the reference edge and at least one of the candidate edges is an acute angle α, the method for obtaining the second search parameter based on the first search parameter includes: Based on the first inward value M_in, obtain the second inward value R_in = M_in; Based on the first start value M_start, the first end value M_end, and the acute angle α, obtain the second outward value R_out = max(M_start, M_end) * sinα; Based on the first outward value M_out and the acute angle α, obtain the second starting value. R_start = M_out / sinα; Based on the first outward value M_out and the acute angle α, obtain the second end value R_end = M_out / sinα.

9. The optical proximity correction method as described in claim 1, characterized in that, After marking the candidate edge as the selected edge, the method further includes: moving the selected edge according to the etching deviation table, so that the corresponding main graphic forms an adjustment graphic, and so that the initial design layout forms a design layout.

10. The optical proximity correction method as described in claim 9, characterized in that, After the main graphic is formed into the adjusted graphic, the process further includes: performing several iterations of optical proximity correction on the design layout.

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