Proximity Ultraviolet Lithography Based On Simulated Annealing Algorithm Of Error Correction

Proximity UV Lithography of photo-resist is the key procedures of UV-LIGA process. The collimation of UV light is low, and there is a diffraction effect. In the process of lithography, diffraction effect caused by the little gap between photo-mask and the surface of photo-resist engenders graphics distortion in contour. For the settling of the graphics distortion, 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 the photo mask. The optimization process is greatly simplified, with yet higher quality. The innovations of this thesis are described as the follow:1. The adverse lithography model based on the Simulated Annealing AlgorithmA Inverse Lithography Technology is adopted in this paper, considered the design of the mask pattern as a converse process, and solving the problem by calculating the whole mask pattern. The complexity of the mask pattern has no effect on the solving process, but the character of the optics system has, the objective mask pattern is just a convergence criterion during the solving process. For in theory the adverse algorithm could traverse overall the function solution space of the mask pattern, so finding a globally optimal solution is possible. The Simulated Annealing Algorithm is adoption as the adverse algorithm, unified the process of minimizing the energy steady state of the anneal system with the process of minimizing the objective function of the optimization, fulfilled the design and optimization of the mask pattern in adverse.2. Selection of the effective region on the mask patternEarly Simulated Annealing Algorithm has an unsatisfactory performance in the convergence efficiency and the precision of optimized result when the objective graph is complicated, to resolve this issue, through analyzing the law of the effective wave-front on diffraction field, obtain the effective region of a graph, and experiments have verified the calculation results. At last, the correction is just carried on the effective region of a graph, the optimization process is greatly simplified and time saving, with yet higher quality.3.Error correction of the designated graphics of proximity UV lithographyOn the basis of correcting the right-angled feature, optimize the mask pattern with right-angled corners in reverse, and inspired by the optimization, with that optimize the mask pattern with arc corners in reverse, make the photo-resist graphics is more close to the original mask pattern.