Abstract

"No sooner than we achieve a goal, we move the goalposts to create a new, more difficult one"¹ Offner’s ring-field all-reflecting triplet was the first successful projection system used in microlithography. It evolved over several generations, increasing NA and field size, reducing the feature sizes printed from 3 down to 1 micron. Because of its relative simplicity it became the dominant optical design used in microlithography until the early 1980’s, when the demise of optical lithography was predicted.

© 1998 Optical Society of America