This work describes a simple process method for obtaining sub-micron and high aspect ratio lateral electrode gaps for rectangular plate micro-resonators and the resulting advantages. The structures are built of [110] single crystal silicon substrate by KOH etching, a novel combined two step oxidation processes and post-process electrostatic actuation method is proposed to achieve nearly smooth vertical walls and 100nm electrode resonator gaps. This is below the fabrication limitation given by conventional optical lithography. The process sequence and simulation results for submicron electrostatic gaps are presented.