Efficient and Robust Synthesis of Phase-Shifting Masks in Optical Lithography

Abstract

Phase-shifting masks (PSMs) are extensively used in semiconductor industry to push the limit of optical lithography. Their synthesis is generally performed via an optimization method under the nominal process condition, and the synthesis process is time-consuming. In this work, we apply a statistical strategy to optimize the average performance with respect to process fluctuations to enhance the robustness of the synthesized PSM pattern, and employ a cascadic multigrid algorithm to improve its computational efficiency. Moreover, we investigate and discuss the impact of the initial pattern on the synthesized result.