Physical modelling of a MEMS based electron tunneling accelerometer

The paper presents a comprehensive physical model of a high precision tunneling accelerometer. It also elaborates the design and optimization of realizing the accelerometer structure in order to achieve targeted specs. Fabrication steps of the accelerometer are CMOS compatible. Moreover the actuation voltage is kept within CMOS bias levels. Electron tunneling based current sensing has been modeled using a quantum mechanical approach. The proposed structure uniquely combines the electron tunneling based sensing and capacitive actuation. A feedback controller is designed to measure the acceleration under constant gap mode of operation. The full dynamic range of operation is 1 mug to 200 mug with mug resolution. The cross- axis sensitivity is less than 1% and the shock survivability is 10 g for a 10 ms shock with 0.1 ms rise time. The Brownian noise floor of the system has also been studied and the squeeze film damping effects on the system has been analyzed. The fabrication steps to realize the accelerometer has been shown.