Modeling of sensitivity of fabricated capacitive pressure sensor

In this work modelling and analysis of a fabricated a fully integrated Double-Ring Capacitive Pressure Sensor (CPS) is described. The sensor fabrication is based on bulk-micromachining process, where silicon is etched from both sides to form a thin diaphragm. The silicon is then sealed by bonding to a glass wafer to form a hermetic chamber. Two metal electrodes which form the capacitor are deposited on the silicon diaphragm and glass, respectively. The difference between the pressures inside and outside of the chamber deforms the diaphragm which, in turn, changes the capacitance. Modelling the sensor capacitance and sensitivity versus applied pressure is given. Simulation results of the sensor capacitance and sensitivity are presented. Also measurement of the sensor sensitivity shows a very high sensitivity of 150 mu V/V-mmHg, which is the main advantage of the fabricated sensor.