High-Sensitivity 4H-Silicon Carbide MEMS Pressure Sensors for Extreme Temperature Ranges of −75 °C to 600 °C

The application potential of silicon carbide (SiC) semiconductor sensors for the surveillance of extreme environmental pressure is considerably promising. Herein, a series of 4H-SiC pressure sensors with different piezoresistor configurations based on microelectromechanical system (MEMS) technology are systematically developed to achieve pressure monitoring within an extreme temperature range from −75 °C to 600 °C. Utilizing femtosecond laser as the principal etching method, augmented by plasma and acid etching, enabled the preparation of thin 4H-SiC membranes with a minimal thickness of 25 μm. This innovative approach resulted in a notable increase in the sensitivity of 4H-SiC piezoresistive pressure sensors to 57.14 mV/MPa at 1.5 mA. The sensor in high-temperature package demonstrates a temperature coefficient of resistance of 427 ppm/°C, a temperature coefficient of zero output of 0.12% FSO/°C, and a temperature coefficient of sensitivity of 0.02% FSO/°C at 600 °C. The 4H-SiC sensor also performs exceptionally well at low temperatures, with its piezoresistor showing a variation of no more than 0.6 Ω at −75 °C. This research provides promising solutions for enhancing the sensitivity and temperature robustness of direct pressure monitoring in industrial systems operating under extreme temperatures.