Extreme Ultraviolet Lithography

Abstract

Extreme ultraviolet (EUV) lithography is a leading contender to access the 32 nm node, and reach the 22 nm node and below. Phase shift masks (PSM) are evaluated as a possible option to push the resolution limit of EUV lithography.Low topology PSM masks have been investigated through optical simulation. Efforts were directed towards low topology structures, so as to reduce shadowing effect, and to determine the effective phase shift. In this paper we will show that phase shift is not only induced by step height but also sensitive to underlying structures.