High-sensitivity material systems for two-photon three dimensional microfabrication

Abstract

A photoacid generator (PAG) is described that can be efficiently activated by two-photon excitation and can be used for high-sensitivity three-dimensional micro-patterning of acid-sensitive media. The molecule has been specifically engineered to have both a large peak two-photon absorption cross section (δ = 690 × 10 -50 cm 4 s photon -1 at 705 nm) and a high quantum yield for the photochemical generation of acid (φ H + ≈ 0.5). Under near-infrared laser irradiation, the PAG produces acid subsequent to two-photon excitation and initiates the polymerization of epoxides. The PAG was used in conjunction with the epoxide resist SU-8 for negative-tone three-dimensional microfabrication and was incorporated into a specially formulated chemically amplified resist for positive-tone fabrication of a three-dimensional grating structure. These material systems expand the potential of three-dimensional microfabrication as a tool for manufacturing micro-electromechanical systems, micro-fluidics, and micro-optical structures.