Electrostatic actuation of surface/bulk micromachined single-crystal silicon microresonators

In fabricating microelectromechanical systems (MEMS), bulk micromachining using (100) and (110) single crystal silicon and surface micromachining using polycrystalline silicon are used. However, both micromachining methods have drawbacks, and micromachining actuating or sensing MEMS using single crystal silicon has been an active research topic in resent years. This paper presents electrostatic actuation of a resonator fabricated by the SBM (surface/bulk micromachining) process. The SBM process allows fabricating released structures in single crystal silicon. To fabricate electrodes and to electrically isolate them, a junction isolation method using reverse-biased diodes is developed. The breakdown voltage of this isolation method is measured to be larger than 150 volts. A SBM processed microresonator is actuated at 36 kHz. A displacement of several μm is achieved in atmosphere with a 20 volts peak-to-peak supply