An efficient two-photon-generated photoacid applied to positive-tone 3D microfabrication

A two-photon-activatable photoacid generator, based on a bis[(diarylamino) styryl] benzene core with covalently attached sulfonium moieties, has been synthesized. The photoacid generator has both a large two-photon absorption cross section (delta=690 X 10(-50) centimeter(4) second per photon) and a high quantum yield for the photochemical generation of acid (phi(H)(+) = 0.5). Under near-infrared Laser irradiation, the molecule produces acid after two-photon excitation and initiates the polymerization of epoxides at an incident Intensity that is one to two orders of magnitude lower than that needed for conventional ultraviolet-sensitive initiators. This photoacid generator was used in conjunction with a positive-tone chemically amplified resist for the fabrication of a three-dimensional (3D) microchannel structure.