Microfabricated Torsional Actuators Using Self-Aligned Plastic Deformation of Silicon.

In this paper, we describe angular vertical-comb-drive torsional microactuators made in a new process that induces residual plastic deformation of single-crystal-silicon torsion bars. Critical dimensions of the vertically interdigitated moving-and fixed-comb actuators are self-aligned in the fabrication process and processed devices operate stably over a range of actuation voltages. We demonstrate MEMS scanning mirrors that resonate at 2.95 kHz and achieve optical scan angles up to 19.2 degrees with driving voltages of 40Vdc plus 13Vpp. After continuous testing of five billion cycles at the maximum scanning angle, we do not observe any signs of degradation in the plastically deformed silicon torsion bars. [ABSTRACT FROM AUTHOR]