Fabrication of comb-drive micro-actuators based on UV lithography of SU-8 and electroless plating technique

Comb-drive microactuators are widely used in MEMS devices. Most of the comb-drive microactuators reported in MEMS field are made using fabrication technology with silicon as the structural material. Recent progress in ultra violet (UV) lithography of SU-8 has made it feasible to fabricate ultra high aspect ratio microstructures with excellent sidewall quality. In this paper, a research work on fabrication and metallization of high aspect ratio SU-8 polymer comb-drive microactuators was reported. The fabrication process combined multi-step and multi-layer UV lithography of SU-8 on a silicon substrate and copper electroless plating to selectively metallize the SU-8 microstructure. The selective electroless plating was achieved by using UV modification of the SU-8 microstructures and the careful control of the exposure dosage. Preliminary experimental results have proved the feasibility of the microactuator and the fabrication technology.