Influence of sensitizer on two-photon initiated polymerization (TPIP) in photoresist SU-8

Abstract

Influence of photosensitizer on two-photon initiated polymerization (TPIP) of epoxide resin have been investigated. The three-dimensional (3D) micro-structures were fabricated to estimate rate of cationic polymerization by using TPIP. The line width and thickness of 3D micro-structures were measured as a function of laser-pulse energy, irradiation wavelength, and scanning speed to elucidate the rate of polymerization (Rp). It was demonstrated that volume of 3D micro-structures depends on the square of input intensity and proportional to two-photon absorption cross section and irradiation time of laser. Rp strongly depends on the quantum yield of H+ rather than efficiency of electron transfer from photosensitizer to initiator. Experimental results were compared with an original mathematical model. ©2007TAPJ.