Hybrid algorithm for reducing mask complexity in inverse lithography technique

초록

In ILT, the mask is usually divided into two-dimensionally array of pixels, and the mask pattern is specified with the amplitude transmittances of all constituent pixels. Basically, SA is the optimization algorithm to search the optimal mask pattern by randomly flipping the amplitude transmittances of every pixel according to a probability. Owing to this global searching nature of SA, the optimized mask pattern cannot but have the very complicate structure. This problem can be overcome by combining SA with well-known bacteria algorithm, where the flipping is limitedly tried to pixels on the boundary of the mask pattern being optimized. The limited flipping will be helpful for reducing the mask complexity as well as the optimization time.