Design and fabrication of a micro-electromechanical system sandwich capacitive accelerometer

This paper reports a micro-gravity MEMS sandwich capacitive accelerometer with symmetrical double-sided folded beam-mass structure. The beam-mass structure is fabricated from a single double-device-layer SOI wafer (D-SOI). The fabrication process produced proof mass with though wafer thickness (860μm) to enable formation of a larger proof mass. The suspension system of eight folded beams with highly controllable dimension suspends the proof mass from both sides. A sandwich differential capacitive accelerometer based on symmetrical double-sided folded beams-mass structure is fabricated by three-layer silicon/silicon wafer direct bonding. The resonance frequency of the developed device is measured in an open-loop system by a network analyzer. The quality factor and the resonant frequency are 18 and 830Hz, respectively. The accelerometer has a closed-loop sensitivity of 1.8V/g and a nonlinearity of 0.52% over the range of 1g.