A Study on Sensitivity Performance of CMOS-MEMS Pressure Sensors utilizing Split Channel MOSFET Structures

Abstract

The paper presents a simulation study on the sensitivity performance of CMOS-MEMS pressure sensors utilizing the Split channel MOSFET structures. These pressure sensors have been designed as split circular curved and split square curved channel MOSFETs integrated on corresponding silicon based circular and square diaphragms. These pressure sensors operate using the piezoresistive effect of MOSFET as a transduction mechanism, referred to as piezo-MOS. The research has been carried out using n-MOS, p-MOS, and CMOS (integrated p-MOS and n-MOS) current mirror circuits. Each circuit has been individually integrated with both diaphragm geometries. The proposed pressure sensors were redesigned using SCL 180 nm CMOS technology, with a 100 μm channel width and 10 μm channel length. The piezo-MOS structure has been split into four segments, resulting in a current mirror integrated split curved channel MOSFET pressure sensor. The mechanical properties of the proposed pressure sensors have been studied using the finite element analysis solver, COMSOL Multiphysics software. The circuit characteristics have been evaluated using Tanner T-Spice. The external pressure ranging from 0 kPa to 450 kPa has been applied to the pressure sensors. The sensitivities of n-MOS, p-MOS, and CMOS (integrated p-MOS and n-MOS) current mirrors, for Split circular curved channel pressure sensor, have been obtained as 122.051, 0.249, and 377.611 mV/MPa, respectively. Similarly, for the Split square curved channel, it has been obtained as 138.821, 0.401, and 492.250 mV/MPa, respectively, for the corresponding readout circuits. The sensitivity variation over different temperature ranges has also been studied and compared for the proposed pressure sensors. Enhanced sensitivity and compatibility with CMOS technology could make the proposed pressure sensors suitable for the nextgeneration pressure sensing devices.