Design and fabrication of silicon-based 8×8 MEMS optical switch array

Silicon-based torsion-beam 8×8 optical switch array are designed and fabricated with bulk silicon micromachining technology. Torsion beams and cantilever beams with reflective micromirror situated on the same wafer are fabricated on (1 1 0) silicon. During fabricating the torsion beam actuating structure, the etched hillocks on (1 1 0) plane are obstacles to achieve smooth torsion beam. It is put forward the reasonable ratios mixtures of HF, HNO₃ and CH₃COOH to improve the processes of fabricating torsion beam actuating structure. The slanted under electrodes that can reduce the actuating voltage are designed and fabricated on tilting (1 1 1) plane by wet chemical etching. According to the etching characteristics of (1 1 1) silicon in KOH solution, two designed photomask patterns are proposed in this paper. According to the experimental results, for the 180 μm displacement of mirrors, the device presents the switching time less than 6 ms and the actuating voltage about 65 V. It shows that this optical switch array can make the meet of the optical communication network.