Catadioptric redn. lens with beam splitter and concave mirror - has no additional lens gp. inserted between mirror and beams splitter giving 4:1 redn. in telecentric system

摘要

A microlithographic pattern in the object plane (0) is imaged onto a wafer (27) by a system incorporating a single convex lens (100), a gp. (200) of five lenses and an exactly cubical beamsplitter (300) with identical exit and re-entry surfaces (14,16). The concave mirror (15) has a fractional magnification and a screen at a distance from the final lens gp. (400) less than its focal length in air. All lenses are of identical quartz glass. USE/ADVANTAGE - With excimer laser for submicron photolithography. Substantially increased aperture on image side is associated with reduced sensitivity to adjustment.