Optical proximity correction in DRAM cell using a new statistical methodology

An optical proximity correction algorithm based on statistical methodology is developed. The responce surface function (RSF) for the CD in the lithographic process is extended by introducing variables for the mask pattern size. The values of process paramemters and mask pattern size are concurrently optimized by using the RSF. This methodology allows design for manufacturbility, considering error distributions of process parameters such as focus position and exposure dose. The algorithm is applied to a DRAM cell pattern. The result indicates the annular illumination with larger coherency than that of the conventional illumination improve the CD limited yield.