Proceedings PaperImproving ArF lens performance and new generation high-NA KrF optical system
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Last year we developed an optics system for new generation ArF scanner. The optics’ NA was 0.85, the lens field size was 26mm X 8 mm and the lens now is equipped onto FPA-6000AS4. Various performance improvements are made to FPA-6000AS4 to respond to tougher and tougher requirement of the lithography process. The optics improvement is not limited to aberration reduction but extends to such lens manufacturing technology as minimizing the impact of birefringence of the glass element at lens assembly. In the first part of the paper enhancement method and accomplishment of lens manufacturing technology is discussed. Lithography technology is not limited only to ArF. We developed 0.86 NA KrF system, too. The system aims to realize easy, inexpensive leading edge lithography by taking advantage of matured, highly performing resist and low process cost. The lens resolves 90nm pattern using usual halftone reticle and goes down to 85nm with strong RET, Levenson mask etc. By utilizing the accomplishments realized for ArF lens, aberration of the lens is extremely small. Performance evaluation result of this high NA KrF lens and extendibility of 248nm with RET is reported in the latter part of this paper.