Sensitivity and Linearity Enhancement of Piezoresistive Pressure Sensor Using Stress Concentration Structure

Piezoresistive pressure sensors are one of the most important and oldest applications of microelectromechanical systems (MEMS). In this paper, a conventional piezoresistive pressure sensor has been simulated and thoroughly analyzed for is output characteristics using finite element method (FEM) tool COMSOL Multiphysics (R). The stress distribution and displacement on the surface of the diaphragm is ascertained and the positions of the piezoresistors are optimized in order to obtain the best possible sensitivity and the linearity of the piezoresistive pressure sensor. The goal in pressure sensor design is to obtain best possible sensitivity, without compromising on the linearity. This goal can be achieved by realizing some structures on the diaphragm, where the stresses are concentrated, namely stress concentration structures (SCS). In this work, a cross beam-membrane (CBM) structure has been taken as a case study for SCS. The conventional pressure sensor structure is compared with CBM structure in terms of sensitivity and linearity using FEM analysis and the results are reported.