POLISHING OF FLUORIDE CRYSTAL OPTICAL LENSES AND PREFORMS USING CERIUM OXIDE FOR MICROLITHOGRAPHY

摘要

The invention provides a means for making below 200 nm VUV optical microlithography lens elements and preforms therefor. The inventive methods include polishing a fluoride optical lithography crystal with cerium to a surface roughness less than five angstroms. The invention includes making a 157 nm VUV optical lithography element preform by polishing a calcium fluoride crystal with cerium oxide polish.