Holographic lithography with thick photoresist

Abstract

Gratings with periods as fine as 199 nm and height-to-width ratios ∼5:1 have been produced directly in photoresist by holographic lithography using a technique that reduces ‘‘orthogonal standing wave’’ problems. The technique uses a single layer of photoresist to attenuate the ‘‘orthogonal standing wave,’’ as well as record the grating pattern. The technique is tolerant of process variations and produces structures suitable for further processing steps such as liftoff and etching.