Method for radiation projection and lens assembly for semiconductor exposure tools

摘要

A lens assembly with materials that densify and rarefy as a function of radiation dose. The lens assembly can be provided for use in photolithographic exposure tools. The combination of densifying and rarefying materials in the lens elements of exposure tools compensates for changes in the index of refraction of the materials. The lens assembly of the present invention corrects, by design, for radiation-induced changes in the indices of refraction of the lens element materials. By compensating for radiation-induced changes, the lens assembly has a longer useful lifetime.