Analysis and simulation for the compensation of distortion in thick film analog lithography

Optical lithography of thick film resist is an important approach to fabrication of continuous microstructures with large depth. However, factors of nonlinear distortion in the pattern transfer process should be taken into account, since these severely affect the profile quality of microstructures. In this work, nonlinear factors in thick film analog lithography are investigated. Combined with the simulated annealing algorithm (SAA), the transmission function of a mask is optimized in order to compensate for distortion in the pattern transfer. The coded gray-tone mask is adopted to realize the corresponding optical modulation based on the optimized transmission function. Simulation results are presented that show that the profile quality with compensation is obviously improved. This method clearly does promote the quality of the profile, but it does not lead to an increase in the difficulty of design and fabrication of the coded gray-tone mask.