Design, Simulation and Analysis of MEMS Capacitive Pressure Sensor

Abstract

This paper presents the analysis of MEMS capacitive pressure sensor using ANSYS and MEMSPro. Metal-Insulator-Metal type of sensor is designed with gold metal electrodes and silicon nitrate dielectric as insulator with a thickness of 10 µm. The pressure sensor design is based on the parallel-plate capacitive configuration in which the membrane deflects due to the input pressure, resulting in the change in the air gap and capacitance. The sensitivity is calculated based on the change in capacitance for various input pressure. The membrane deflection, capacitance and sensitivity of the pressure sensors are simulated and analyzed upon variations in input pressure, membrane material and membrane geometry using ANSYS. The input pressure range exerted on the membrane is from 0 kPa to 200 kPa. Flexible membrane materials simulated and analyzed are silicon carbide, silicon nitrate, aluminum oxide and aluminum nitride with three membrane geometries: circular, square and octagonal. From the simulation results of various membrane geometries and membrane materials, the most suitable configuration of the MEMS Capacitive Pressure Sensor is circular membrane made of silicon nitrate which has the highest sensitivity of 9.18 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-18</sup> pF/Pa at 200 kPa. In this paper, the fabrication process of the pressure sensor is also simulated and a 3D model is generated using MEMSPro.