A Simulation Approach to Study the Effect of SiC Polytypism Factor on Sensitivity of Piezoresistive MEMS Pressure Sensor

SiC is a well known wide band gap semiconductor explored for realizing the piezoresistive micro-electro-mechanical systems (MEMS) pressure sensors for harsh environments. In this work a thin SiC diaphragm based piezoresistive pressure sensor was designed by locating the resistors of different SiC polytypes such as 3C, 4H, and 6H-SiC, on highly stressed zone of the diaphragm and analyzed. The sensor design parameters were extensively studied by executing the finite element method (FEM) and piezoresistive simulation using device simulation software. The sensor characteristics were measured for different SiC polytypes and compared for different design parameter variations to obtain the optimum sensor performance under the influence of the pressure upto 8 MPa. Influence of temperature for heavily doped SiC polytypes is also studied. The simulation results shows that the pressure sensor with 3C-SiC polytype offers higher sensitivity 7.3 mu V/V/KPa as compared to 4H-SiC and 6H-SiC polytypes.