Optical proximity correction process

An optical proximity correction process for designing a mask with a pattern, wherein the pattern has a plurality of edges, the mask with the pattern is designed according to a target exposure intensity of each of the edges, each of the edges is at a corresponding current edge position on the mask and each current edge position corresponds to a current exposure intensity, the optical proximity correction process comprising:

• repeating a convergence process on each of the edges of the pattern to determine an adjusted position for each of the edges of the pattern until an adjusted exposure intensity of each of the edges at the adjusted position is substantially equal to the corresponding target exposure intensity, wherein, for each of the edges, the convergence process comprises:
• comparing the target exposure intensity with the current exposure intensity to determine an in-position of the edge correlating to a first exposure intensity and an out-position of the edge correlating to a second exposure intensity, wherein the target exposure intensity is within a range between the first exposure intensity and the second exposure intensity;
• performing an interpolation to obtain the adjusted position of the edge between the in-position and the out-position on the mask according to the target exposure intensity;
• and
• updating the pattern so that the edge is shifted from the current edge position to the adjusted position and assigning the adjusted position to be the current edge position of the edge.