Comparison of mechanical deflection and maximum stress of 3C SiC- and si-based pressure sensor diaphragms for extreme environment

The design of a capacitive-sensing pressure sensor for extreme environment is proposed in this project. The movable diaphragm (top plate) is made of either cubic silicon carbide (3C-SiC) or Silicon (Si), while the fix diaphragm (bottom plate) is made of Si. This paper specifically compares the mechanical performance of the movable diaphragm utilizing both materials. Two important parameters associated with the behavior of the diaphragm are examined, namely the maximum deflection and maximum stress, and they are simulated at a pressure of 0-100 MPa, and at temperature of 27-1000 °C. The graphs of maximum deflection and stress vs pressures at different temperatures and thicknesses are plotted to summarize the data. SiC diaphragm has lower deflection and stress compares to Si diaphragm at different thicknesses, pressures and temperatures. Then, a linear regression analysis is performed to determine the R-square value. It is shown from these analyses that SiC diaphragm exhibits better linear behavior compares to Si diaphragm. Generally, this work proves that SiC is a better material over Si for the development of a pressure sensor at extreme environment.