Optimization design of immersion magnetic lenses in projection electron beam lithography

In this paper, a novel immersion magnetic lens used for projection electron beam lithography is optimized by Powell method. The optimized structure of an immersion magnetic lens can be reached with a criterion of minimum obje ctive parameter, which is the value of curvilinear axial astigmatism in the present paper. The results show that axial astigmatism is decreased from 2 43 nanometer to 50 nanometer after optimization. It can be seen that the Po well method is suitable for the optimization design of immersion magnetic l enses.