CN-115755518-B - Optical proximity correction method of layout and storage medium

CN115755518BCN 115755518 BCN115755518 BCN 115755518BCN-115755518-B

Abstract

The invention discloses an optical proximity correction method and a storage medium of a layout. The optical proximity correction method of the layout comprises the steps of establishing an expansion block corresponding to an initial block based on the initial block, wherein the expansion block comprises a core area with a size smaller than that of the initial block and an inner buffer area arranged around the core area, conducting OPC cyclic iteration operation on the expansion block corresponding to the initial block according to the priority of the initial block, averaging the vertex positions of geometric figures in an overlapped operation area of two adjacent expansion blocks when the OPC cyclic iteration operation is not conducted to the last cyclic iteration operation, conducting the next cyclic iteration operation, otherwise, averaging the vertex positions of geometric figures in the overlapped operation area of the two adjacent expansion blocks, and conducting the last OPC cyclic iteration operation on the core area only by taking the inner buffer area as the boundary condition of the core area. The invention can realize the convergence of the edges of the blocks.

Inventors

Du Yaojuan
Pei Zhuoran
XIAO GANG
CHEN HONG

Assignees

深圳国微福芯技术有限公司

Dates

Publication Date: 20260505
Application Date: 20221202

Claims (6)

1. An optical proximity correction method of a layout is characterized by comprising the following steps: performing partitioning processing on the layout to obtain initial partitions, and defining the priority of the initial partitions so that the priority of each partition is different from the priorities of the peripheral partitions; based on the initial block, establishing an expansion block corresponding to the initial block, wherein the size of the expansion block is larger than that of the initial block, and the expansion block comprises a core area with the size smaller than that of the initial block and an inner buffer area arranged around the core area; When the expansion block carries out OPC circulation iteration operation, an outer buffer area is arranged around an inner buffer area of each expansion block, the expansion block and the outer buffer area corresponding to the expansion block are used as one block to carry out OPC circulation iteration operation, and the part, close to the outer buffer area, of the inner buffer area is overlapped with the outer buffer area by two adjacent expansion blocks; when the OPC loop iteration operation is not carried out to the last loop iteration operation, after the OPC loop iteration operation is completed, averaging the vertex positions of geometric figures in the overlapped operation areas of two adjacent expansion blocks, and carrying out the next loop iteration operation; when the cyclic iterative operation of the OPC is the last cyclic iterative operation, the vertex positions of geometric figures in the overlapped operation areas of two adjacent expansion blocks are averaged, the inner buffer area is used as the boundary condition of the core area, and the cyclic iterative operation of the OPC of the last round is only carried out on the core area.
2. The method for optical proximity correction of a layout according to claim 1, wherein vertical distances from each boundary of the core area to a center of the initial segment are equal.
3. The optical proximity correction method of a layout according to claim 2, wherein vertical distances from each boundary of the inner buffer area to a center of the core area are equal.
4. The optical proximity correction method of a layout according to claim 3, wherein the width of the core area is W-L, the width of the inner buffer area is 2L, and W is the width of the initial block.
5. The method for optical proximity correction of a layout according to claim 1, wherein the priorities of the initial blocks are 4 kinds of priorities in total.
6. A computer readable storage medium storing a computer program, wherein the computer program when run performs the method of optical proximity correction of a layout according to any one of claims 1 to 5.

Description

Optical proximity correction method of layout and storage medium Technical Field The invention relates to the field of semiconductor manufacturing, in particular to a processing method of OPC operation of a layout. Background In order to transfer the pattern from the reticle to the surface of the silicon wafer, an exposure step, a development step performed after the exposure step, and an etching step after the development step are generally required. In the exposure step, light irradiates the silicon wafer coated with photoresist through a light-transmitting area in the mask, the photoresist is subjected to chemical reaction under the irradiation of the light, in the development step, a photoetching pattern is formed by utilizing the difference of the dissolution degree of the photosensitive photoresist and the non-photosensitive photoresist to the developer, the transfer of the pattern from the mask to the photoresist is realized, and in the etching step, the silicon wafer is etched based on the photoetching pattern formed by the photoresist layer, and the pattern of the mask is further transferred to the silicon wafer. In semiconductor manufacturing, as the design size is continuously reduced, the design size is more and more close to the limit of a photoetching imaging system, the diffraction effect of light becomes more and more obvious, optical image degradation is finally generated on a design pattern, the actually formed photoetching pattern is severely distorted relative to the pattern on a mask plate, and finally the actual pattern formed by photoetching on a silicon wafer is different from the design pattern, and the phenomenon is called optical proximity effect (OPE: optical Proximity Effect). In order to correct the optical proximity effect, an optical proximity correction (OPC: optical Proximity Correction) is generated. The core idea of the optical proximity correction is to build an optical proximity correction model based on the consideration of canceling the optical proximity effect, and design a photomask pattern according to the optical proximity correction model, so that although the optical proximity effect occurs in the lithographic pattern corresponding to the photomask pattern, since the cancellation of the phenomenon has been considered when designing the photomask pattern according to the optical proximity correction model, the lithographic pattern after lithography is close to the target pattern that the user actually wants. Currently the dominant technology node (65 nm and below manufacturing process) employs model-based OPC corrections. The mask is first optically modeled using the hopkins equation (Hopkin's equation) and the intensity distribution in air is obtained (AERIAL IMAGE). And then the light intensity distribution in the air is converted into photoacid distribution (RESIST IMAGE) in the photoresist by a photoresist compact model (compact model). The photoresist pattern after photoresist removal can be directly obtained by the distribution of the photoacid. Model-based OPC corrections themselves require a significant amount of computational resources. In particular, the size of the individual chips in the advanced nodes can be of the order of centimeters and the pattern density is high (pitch <100 nm). Model-based OPC corrections to such chips must employ distributed computation to reduce Turn Around Time (TAT) to an acceptable level. The current practice is to divide the entire layout into a number of blocks (as shown in fig. 1) of 20-30 microns. As shown in fig. three, the current OPC-based distributed processing of the blocks causes a problem of non-uniformity of the block edge area pattern. In the third diagram, the priority of the center block is priority-1, and the center block must wait for the end of OPC on the block with priority-0 around, before the OPC calculation can be started. In the center-block OPC calculation process, the patterns in the surrounding 8 blocks the neighboring tiles (2 blocks with priority 0, 2 blocks with priority 3 and 4 blocks with priority 2) remain unchanged and serve as reference patterns (boundary conditions) for the center block. The edge pattern of the center tile is affected by the adjacent 8 tiles. When an adjacent tile, such as a tile with a priority of 3, begins an OPC calculation, its edge pattern is again affected by the center tile. Such repeated cycling makes it difficult for the pattern of the tile edges to converge. Disclosure of Invention In order to solve the technical problem that edges cannot be converged when the layout is subjected to OPC correction processing in the prior art, the invention provides an optical proximity correction method and a storage medium of the layout. The optical proximity correction method of the layout provided by the invention comprises the following steps: Partitioning the layout to obtain initial partitioning, and defining the priority of the initial partitioning; based on the initial b