Characterization of the polymerization of SU-8 photoresist and its applications in micro-electro-mechanical systems (MEMS)

In this paper, we report the optimization results of SU-8 EPON-based photoresist (PR) polymerization and its possible microfluidic and MEMS applications. First, the optimization results of SU-8 polymerization under near UV lithography are reported. The parameters which could have influence on the lithography quality were chosen and optimized by a three level, L9 Orthogonal Array of Taguchi Method. By optimization, the optimal range and the weighted percent effect of different parameters on the final results were determined. For SU-8 5 and SU-8 50, many microstructures with thickness more than 100 or 500 mum and aspect ratio more than 20 or 50 respectively, were obtained with high resolution. The optimization results had shown that prebake time plays a key role in the quality, which was different from the previously published results. With the optimization results obtained, some possible applications of SU-8 were developed and demonstrated. These applications included using SU-8 as a structural material for microfluidic systems like microcapillary electrophoresis system, as a micromold for electroplating, as a master for plastic hot-embossing, and as a mask for some wet-etching processes. Some other possible applications were also reviewed. (C) 2001 Elsevier Science Ltd. All rights reserved.