Design and Fabrication of an SOI Optical Switch with Backside Release for Anti-high-Overload

This paper presents a new method for wafer-level packaging of MEMS silicon-on-insulator (SOI) sensors and actuators working in the situation of over-loading. The developed process starts with backside deep reactive ion etching (DRIE) of the substrate to define the support structures as down stop blocks. This is followed by hydrofluoric acid etching to remove excessive SiO2 layer underneath the structural area to free the movable device parts. Then, another step of DRIE was applied on the device layer to form the device features. As the area of support structures are much smaller than proof mass, no stiction was observed. Finally, a glass wafer was used to encapsulate the switch using an anodic bonding technique to form a up stop block. In the work described here, the process is demonstrated for micromachining of an optical switch surviving from the high-impact overload environment at 20,000 g with pulse-width 120 μs.