Design and Optimization of Photomask Based on the Phase Field Model Considering Manufacturability

摘要

This paper proposes a new design and optimization approach of photomask based on the phase field model. A phase field function is used to represent different material regions by a novel nonlinear exponential mapping, which can suppress the intermediate gray values. The design sensitivity is derived and filtered for obtaining the smoothed shape derivative. The perimeter constraint based on the phase field function is proposed for tackling the ill-posedness problem which also has effect on the smoothness of the optimized mask considering the mask manufacturing. The optimal geometric layout of mask is obtained by solving the Allen-Cahn equation without re-initialization. Finally, results with different initializations for partially coherent system with annular illumination are presented to show the advantages of the proposed method for the shape optimization of photomask.