Analytical modeling and simulation of MEMS piezoresistive pressure sensors with a square silicon carbide diaphragm as the primary sensing element under different loading conditions

摘要

Although silicon is the preferred choice for microelectromechanical systems (MEMS) piezoresistive pressure sensors, such devices are not preferred for application in harsh environmental conditions due to the exponential increase in leakage current with temperature. To alleviate such shortcomings of silicon-based pressure sensors in extreme conditions including elevated temperature and intense vibration, this study strives to shift focus from core complementary metal–oxide–semiconductor (CMOS) materials to silicon carbide. In this work, we adopt an analytical and simulation approach to model and analyze various characteristics of such silicon carbide piezoresistive sensors and determine an optimal design. A square diaphragm is modeled using the analytical expressions for a thin plate in combination with small-deflection theory, providing quick insight for estimation of critical parameters and thus the behavior of the pressure sensor. Both clamped and freely supported edge conditions of the diaphragm are explored. Although many studies and discussions are available on the rigidly supported loading condition, the freely supported edge condition for a square diaphragm has received little attention. The deflection, stress, strain, and sensitivity of the square diaphragm under both loading conditions are reported herein then compared to understand which of the two loading conditions results in more significant outputs.