An improved fabrication process for realization of vertical comb capacitors is proposed, which can suppress the lateral etching problem in the normal silicon-on-glass process due to the heat conduction problem during the over etching. An out-of-plane electrostatic actuator with in-situ position sensing comb capacitors was fabricated to verify the feasibility of the proposed process. The total range of the open-loop static actuation is measured to be 13μm with the maximum actuation voltage of 32 volts.