Patterning flood illumination with microlens arrays

Abstract

We describe a convenient lithographic technique that can produce simple, repetitive micropatterns over large areas (several square centimeters). The technique uses an illuminated array of micrometer-scale lenses to generate an array of optical patterns in an image plane located within micrometer distances from the lens array. A layer of photoresist, placed in the image plane, records the patterns. Microlenses with different sizes, profiles, composition, and indices of refraction produce corresponding patterns in exposed and developed photoresist. Both spherical and nonspherical microlenses were examined. Several types of optical element containing arrays of microlenses were fabricated and used to demonstrate that this technique can generate uniform micropatterns over large areas (>4 cm2) in a single exposure. The smallest features produced had dimensions of approximately 100 nm.