A film bulk acoustic resonator-based high-performance pressure sensor integrated with temperature control system

Abstract

This paper presented a high-performance pressure sensor based on a film bulk acoustic resonator (FBAR). The support film of the FBAR chip was made of silicon nitride and the part under the resonator area was etched to enhance the sensitivity and improve the linearity of the pressure sensor. A micro resistor temperature sensor and a micro resistor heater were integrated in the chip to monitor and control the operating temperature. The sensor chip was fabricated, and packaged in an oscillator circuit for differential pressure detection. When the detected pressure ranged from −100 hPa to 600 hPa, the sensitivity of the improved FBAR pressure sensor was −0.967 kHz hPa−1, namely −0.69 ppm hPa−1, which was 19% higher than that of existing sensors with a complete support film. The nonlinearity of the improved sensor was less than ±0.35%, while that of the existing sensor was ±5%. To eliminate measurement errors from humidity, the temperature control system integrated in the sensor chip controlled the temperature of the resonator up to 75 °C, with accuracy of ±0.015 °C and power of 20 mW.