John H. Burnett, Zachary H. Levine & Eric L. Shirley, National Institute of Standards and Technology, Gaithersburg, MD, USA

ABSTRACT

Calcium fluoride and other crystalline fluoride materials are being exploited for latest generation lithography optics, making up a significant component of the optics of 193 nm lithography systems and being potentially the exclusive optical materials for 157 nm systems. Improvements in the crystalline material quality seemed to have brought the most troubling material property, stress-induced birefringence, into specification.