Abstract

Since only fused silica can be obtained with good enough homogeneity, most lithographic objectives for use below 300 nm are only corrected for very narrow wavelength ranges. As a result these objectives have to be used with wavelength narrowed excimer lasers. By going to catadioptric objectives both high N.A. and moderate chromatic correction can be obtained, still using only one material. A first such objective was built for use with a mercury source at 248 nm. A second objective is being built for use with an argon fluoride laser at 193 nm. The design and the methods used in building these objectives will be described.

© 1992 Optical Society of America