SOI-based fabrication processes of the scanning mirror having vertical comb fingers

Abstract

A 1500 μm×1200 μm scanning mirror having vertical comb fingers has been fabricated by using silicon-on-insulator (SOI)-based fabrication processes. It is a vertically driven electrostatic scanner and composed of two structures having vertical comb fingers. The comb fingers are etched by deep inductively coupled plasma reactive ion etching (ICPRIE) and assembled by the flip chip aligner bonder. The buried oxide layer is used as an etch stop to acquire the uniform thickness of torsion bars of the upper structure. Using an oxide mask process, we acquired the uniform comb fingers at the lower structure without the planarization process. The handling difficulty of a thin silicon wafer is improved by using an anodic bonding and following mechanical polishing. This scanning mirror showed a linear actuating performance. It can be used for laser display as a galvanometric vertical scanner.