Reliable before-fabrication forecasting of MEMS piezoresistive pressure sensor: mathematical modelling and numerical simulation

Micro-mechanical systems (MEMS) based piezoresistive pressure sensors have significant importance in several pressure sensor devices in real world, i.e., aviation, IoT and consumer electronics, nuclear and thermal power plants. Mathematical analysis for modelling piezoresistive pressure sensors is gaining significant importance. MEMS piezoresistive pressure sensors utilize diaphragms of several shapes and geometries. In this work, a MEMS piezoresistive pressure sensor having a square diaphragm and piezoresistive elements attached in a Wheatstone bridge configuration useful in harsh environmental conditions has been thoroughly analyzed and presented. Silicon carbide (SiC) has higher Young's Modulus, carrier mobility, corrosion tolerance, Poisson's ratio, poses extreme chemical inertness and is extremely wear resistant-properties which are absolutely essential for application in harsh environments. Hence, Silicon carbide is most preferred for fabricating these sensors. Sensitivity is a crucial parameter that defines the sensor's performance. According to thin plate mechanics, thinner the diaphragm membrane, more it has deflection, stress and sensitivity, but it deteriorates the linearity of the sensor which happens to be a crucial parameter. Thus, optimal structural parameters need to be chosen to improve the sensitivity of the pressure sensor. Different device characteristics of these sensors have been measured, analyzed and compared to get the best performance out of them. The simulation of this piezoresistive pressure sensor is carried out in MATLAB. The authors have presented a detailed mathematical model in this work which assists in assessing the affectability of piezoresistive SiC-based pressure sensors analytically and their working in harsh environmental conditions prior to going for the fabrication process.