Imaging patterns of intensity in topographically directed photolithography

Abstract

This article describes a process that consists of embossing a bas-relief pattern into the surface of a layer of photoresist and flood illuminating the embossed resist; this process uses the topography of the resist to generate a pattern of optical intensity inside the resist layer. Development of embossed, illuminated (λ=365–436nm) photoresist yields structures as small as 70nm. Numerical solutions of the Fresnel integral are used to calculate the pattern of intensity of light in the photoresist layer. Numeric simulation of a nondiffusion-limited development process results in theoretical structures that correlate well with the structures generated experimentally.