Design, Simulation & Analysis of SOI based Micro Piezoresistive Pressure Sensor for High Temperature Applications

MEMS sensors are of great demand in the current era as in the recent years the world is turning smarter. MEMS pressure sensors are the most primitive commercialized sensors. Even though the MEMS pressure sensor design and manufacturing started way back in 1960's, there is still an increasing demand in the design and development of these sensors. Silicon is extensively used in the development of pressure sensors. In recent years the application bandwidth of these sensors has become wide. The paradigm of sensor development is now shifting towards the use of materials like SOI SiC, Diamond like Carbon etc., as they can with stand harsh environments involving high pressure & high temperatures. This paper presents design, simulation and analysis of a SOI Micro Piezoresistive Pressure Sensor, which provides better sensitivity at high temperatures compared to silicon piezoresistive pressure sensors. The design of the Si and SOI sensors has be optimally done, which enhances the sensitivity. The designed SOI pressure sensor model provides a sensitivity of 266mV/MPa. The paper also presents the design of the sensors using double Wheatstone bridge pressure measurement mechanism, which further enhances the sensitivity of the SOI sensor to 298mV/MPa over the Silicon only based sensor. Here the double Wheatstone bridge serves as a temperature compensation, providing capability of the sensor to operate with better sensitivity at high temperatures. The sensors are analyzed for parameters like displacement, output voltage, temperature, sensitivity & non-linearity. Overall the designed SOI pressure sensors shows better sensitivities both at normal and high temperature compared to Si pressure sensor.