The design and simulation of a MOSFET-based MEMS pressure sensor using an integrated simulation approach

Abstract

A novel integrated design and simulation approach is applied to analyze the performance of a metal–oxide–semiconductor field-effect transistor (MOSFET)-based microelectromechanical systems (MEMS) pressure sensor circuit while varying circuit and CMOS parameters, viz. the supply voltage and threshold voltage (Vt), respectively. For effective mechanical pressure sensing, a sensor MOSFET is integrated near the fixed edge of a deformable silicon diaphragm for maximum stress exposure. The stress value where the sensor MOSFET is located on the diaphragm surface is calculated using the finite-element method (FEM). Additionally, the threshold voltage required to activate the sensor MOSFET is also extracted using the FEM. The extracted value of Vt along with the corresponding gate oxide thickness are used to design and simulate the sensor circuit in the SPICE tool. The FEM-based multiphysics simulation is linked to a standard direct-current (DC) model SPICE simulation using our proposed carrier mobility model for a MOSFET under mechanical stress. All the FEM computations are performed using COMSOL Multiphysics, all the electrical simulations are performed using LT-SPICE, and the full sensor circuit is designed and simulated by integrating COMSOL Multiphysics and LT-SPICE via a MATLAB script. The validity of the design is confirmed by comparing these results with analytical computations. The results obtained using the integrated simulation approach confirm that the design is reliable and enable the sensor performance to be examined in terms of its sensitivity, yielding a value of 30 mV/MPa.