Design and Fabrication of a Dual-Axis MEMS Electrostatic Micromirror Based on a Planar Comb Drive

This paper designs and fabricates an electrostatic-driven dual-axis MEMS micromirror capable of out-of-plane torsional motion about both the X and Y axes. Both torsional axes employ planar comb structures for their drive mechanisms, effectively reducing the fabrication complexity. By leveraging the structural asymmetry introduced during processing in conjunction with resonant operating modes, the inherent disadvantage of planar comb structures for torsional motion is overcome. This study explores the operating principle, structural design, performance simulation, fabrication process, and testing of the micromirror. It proposes an indirect simulation method suitable for planar comb drive structures, providing theoretical support for device fabrication. During fabrication, optimising the removal of isolation material through oxygen-silicon growth enhances the reliability of subsequent processes. Test results demonstrate that the fabricated MEMS micromirror achieves a 26°×22° field of view at a 35 V drive voltage, outputting Lissajous-type scanning patterns. This design aims to propose an indirect simulation method and optimise the process accordingly. Experimental test results show that the simulation method is relatively accurate, with minimal deviation from actual tests. Process optimization improves wafer cleanliness and reduces the time cost of the corresponding process.