A novel electrostatic vertical comb actuator fabricated on [111] silicon wafer

In this study, a novel electrostatic vertical comb actuator (VCA) is designed and fabricated on a [111] silicon substrate. The BELST process was exploited to fabricate the proposed VCA. Three advantages for this VCA can be observed. Firstly, through some exquisite design the fabrication process has no critical alignment and bonding problems. Secondly, the relative vertical position between the moving and the stationary finger can be adjusted freely to optimize the performance of the VCA. Thirdly, both the large mirror structure and trimmed torsional spring are available through this process. Thus improved performance regarding enlarged traveling distance with reduced driving voltage can be obtained. According to the static test, this VCA can achieve optical scanning angle near 5 degree when driven at 90 V Moreover in the dynamic test, this actuator can deliver a significant output when driven near 4.1 kHz.