Simultaneous Formation of Non-coplanar Resonant Beams and Supporting Beams of Bulk Micromachining Resonant Accelerometers by Maskless Anisotropic Wet Etching

Abstract

The paper presents the design principles and fabrication sequence of a newly developed mechanical structure of bulk micromachining resonant Z axis accelerometers on the same silicon substrate by maskless anisotropic wet etching technique. Four resonant beams are located at the top surface of silicon substrates in order to facilitate the patterning of excited resistors, piezoresistive resistors or electrode plates, whereas the gravity centre of the proof mass lies within the neutral plane of eight supporting beams to minimize the rotating of proof mass under in-plane acceleration. Compared with early reported mechanical structures, the simple structures can eliminate the bending moments caused by in-plane acceleration, as a result, avoid the rotating of the proof mass.