High-Linearity MEMS Accelerometer with Lateral Comb Finger Groups

Abstract

Most capacitive MEMS (Microelectromechanical Systems) accelerometers sense capacitance gap change due to inertial force. Since capacitance is inversely proportional to capacitance gap, this results in nonlinearity of its output response. In this paper, a high-linearity and high-sensitivity capacitive MEMS accelerometer based on overlap length change instead of capacitance gap change has been reported. Since capacitance is directly proportional to the overlap length, the proposed accelerometer has inherent high-linear relationship between its differential capacitance output and input acceleration. The proposed accelerometer utilizes threefold beam structure, which leads to improved device sensitivity. The working principle of the accelerometer is discussed. Theoretical analysis was performed to guide the device design optimization. The proposed MEMS accelerometer is to be fabricated with bulk-micromachining using silicon DRIE (deep reactive ion etching) and silicon-glass anodic bonding techniques. ANSYS simulation is used to verify the function of the designed MEMS accelerometer.