Analysis and compensation of shape distortion in UV-LIGA based on partial coherent light theory

摘要

How to fabricate high aspect ratio microstructures with high precision has become a very concerned issue. In this paper, the pattern transfer accuracy of proximity lithography is investigated and the related distortion compensation method is presented. According to partial coherent light theory, the propagation of partial coherent light, which is from an extended quasi-monochronmatic source and transferring through the illumination system, is analyzed. And based on the complex degree of coherence for any two points on mask plane, a mathematical model is constructed to analysis the propagation of mutual intensity from mask to photo-resist and the intensity distribution is attained. With the aerial image of mask pattern, the photo-resist profile is simulated. Then the pattern distortion is investigated, especially on the edges and corners of the profile. And a mask optimization method using genetic algorithm is proposed to improve pattern transfer accuracy. Theoretical model indicates an effective way for resist shape distortion analysis and compensation.