A novel out-of-plane MEMS tunneling accelerometer

A novel out-of-plane MEMS tunneling accelerometer is designed, fabricated and characterized. ICP process, which can generate large proof mass, is used for the first time to fabricate an out-of-plane tunneling accelerometer. To reduce the high Hooke's constant in out-of-plane direction of the ICP etching structure, the beams and the proof mass are dry-etched by double mask ICP process, which reduce the Hooke's constant, thereby enhance the sensitivity of the device. The tunneling current of open loop is tested in the air by HP4145B semiconductor analyzer, which verifies the presence of tunneling current and shows the needed driving voltage. The close-loop test shows sensitivity of 811 mV/g for feedback voltage (the sensitivity of actuate voltage is about 200 mV/g) and nonlinearity of 1% in the measurement range of 0 to +1 g. The spectrum measurement is performed in general environment and the resolution of the device is 0.5 mg/rtHz (1.25-100 Hz), which shows better low frequency property.