Projection system design method, lithography apparatus, and device manufacturing method

PROBLEM TO BE SOLVED: To provide a method of designing a projection system for a lithography projection apparatus, to provide a lithography apparatus comprising the projection system, and to provide a method for manufacturing a device by using the projection system. ; SOLUTION: In the first place, local optimization of the projection system is performed and a starting configuration corresponding to a local minimum point of a merit function is determined, or merely a known minimum point system is used as the starting configuration. In the next place, a zero thickness meniscus lens is inserted to faces in a local minimum point starting configuration having N pieces of faces, a saddle point having Morse index=1 which has N+2 pieces of faces is constructed, perturbation is added and optimization is performed on both sides of a saddle. Distances on introduced two faces are increased and two new configurations m1, m2which are new minimum points of the merit function are created. Resultantly, the respective configurations are output as computer file to be used for preparing an actual projection system, for example, as a table of parameters defining specification of the projection system.Applied Science