Design and Numerical Simulation of Capacitive Pressure Sensor Based on Silicon Carbide

In this study, a capacitive pressure sensor based on silicon carbide is designed and simulated. This sensor is suitable for extremely harsh environments such as high hydraulic pressure and high temperature. This study aims to overcome the challenges faced by conventional silicon capacitive pressure sensors that suffer from small range and high-temperature intolerance. The sensor consists of an aluminum nitride (AlN) ceramic substrate and a silicon carbide sensing chip encapsulated on the substrate. It utilizes a cylindrical sandwich structure based on a vacuum cavity to ensure high sensitivity and low nonlinearity of the output capacitance. The key structural parameters of the new device were optimized using Taguchi's method to achieve the optimal dimensions. In Section IV-C , the temperature characteristics of the sensor are investigated based on the optimal structural dimensions. The results yield a maximum sensitivity of 1.34 fF/MPa for the novel capacitive pressure sensor with a low nonlinearity of 0.094 FS over the pressure range of 0-150 MPa when temperature effects are not considered. When temperature effects are considered, the sensitivity of the sensor increases with operating temperature. At an operating temperature of 20 °C and a bonding temperature of 70 °C, the sensor has a sensitivity of 1.25 fF/MPa and a nonlinearity of 0.089 FS. In addition, a hysteresis of 0.35% FS and a repeatability of 0.02% FS were obtained based on the results of three pressure cycles.