Development of Laser-Micromachined 4H-SiC MEMS Piezoresistive Pressure Sensors for Corrosive Environments
Lukang Wang, You Zhao, Yu Yang, Xing Pang, Le Hao, Yulong Zhao, Jiakai Liu
Abstract
Making full use of the availability and excellent performance of silicon carbide (SiC) substrates, SiC-based MEMS piezoresistive pressure sensors have been extensively investigated. In this article, a femtosecond laser was adopted instead of dry plasma etching technology to realize mass fabrication of 128 bulk SiC piezoresistive pressure sensor diaphragms from half a 4H-SiC wafer. These diaphragms were completed in 2 h with an average thickness error of less than 7.5% and a surface roughness of 108 nm. The 4H-SiC sensor was characterized with a nonlinear error of 0.13% FS and a repeatability error of 1.49% FS in the pressure range of 0–5 MPa at room temperature. The tolerance to temperature was measured in high and low temperature of −50 °C–300 °C with the temperature coefficient of sensitivity (TCS) of −0.11% FS°C at −50 °C and −0.16% FS°C at 300 °C. In addition, resistance measurement of the sensor in strongly alkaline corrosive solution proved the robustness with an average daily drift of only 1.61%. This integrated solution that combines femtosecond laser technology and MEMS processing provides exciting opportunities for rapid and large-scale manufacturing of bulk SiC pressure sensors.