Performance optimization of SiC piezoresistive pressure sensor through suitable piezoresistor design

Silicon carbide is considered as a more suitable material for piezoresistive pressure sensors in a high-temperature environment due to its excellent characteristics. In this paper, fundamental research on the structural design of SiC piezoresistive pressure sensors was carried out through the finite element method (FEM) to accurately estimate the optimal output characteristics. The effects of various boundary conditions on the deflection and stress distribution of SiC circular diaphragm were analyzed to determine the difference between the edge-clamped structure in traditional theory and the bottom-fixed structure in actual pressure sensors. Furthermore, on the basis of appropriate boundary conditions, the design considerations for SiC piezoresistors were discussed in detail to study the influence of different parameters on the sensitivity and nonlinearity of pressure sensors, including the shape, placement, dimension, and connection methods with metal lines. Both simulation results and theoretical analysis indicated that the suitable piezoresistor design can achieve larger resistance variations in both longitudinal and transverse piezoresistors and less difference between them, which is beneficial to the performance optimization of SiC piezoresistive pressure sensors.