New Vertical Array Actuators Using Extended Sbm And Deep Pn Junction Isolation

Abstract

This paper presents a single-wafer, large-displacement electrostatic vertical motion actuator, using the extended sacrifical bulk micromachining (SBM) technology. The driving scheme is a torsional lever mechanism that achieves a large vertical displacement, which is achieved using a low driving voltage by novel small-gap vertical combs. The extended SBM process is used to fabricate combs that have different heights. These combs achieve about 10 μm vertical motion at 60 volts. The vertical displacement on the opposite end is 30 μm by the 3:1 lever ratio. A new process for electrode isolation is also developed for hign aspect ratio microstructure. The process uses doping sidewalls for an effective PN junction. The developed process is used to fabricated a single on-off optical switch as well as a 4×4 array switches. The switches use shutters for optical switching. The fabricated optical switch has a 2.3 degree of tilt angle at a 60 V driving voltage. The 2.5 degree tilt angle gives 30 μm displacement at the optical shutter. Optical signal off to on time is 0.09 ms and optical signal on to off time is 0.10 ms, which is sufficiently fast for optical switch applications.