Optimization of partial photo mask based on wave-front division theory in proximity lithography

Graphics distortion caused by the diffraction in proximity lithography exposure process in UV-LIGA technology affects quality of MEMS structure.A theoretical model based on wave-front division is presented.The mask pattern is divided into sub-regions and the impact of their wave-fronts on the diffraction field is investigated.For interference cancellation of the diffraction light,disturbances caused by wave-front on some regions are equal to zero approximatively.So a special region can be finally attained,in which the wave-front has the most contribution to the field point and experiments have verified the calculation results.A method which employed the Simulated Annealing Algorithm(SA)was studied to optimize the characteristic regions of photo mask.The optimization process is greatly simplified,with yet higher quality.