On-Diaphragm Thermistor for High-Temperature Dynamic Pressure Sensors

This article presents the fabrication and characterization of on-diaphragm Pt thermistors for temperature-compensated calibration of piezoelectric pressure sensors. The micromachined pressure-sensitive diaphragms are 700 μm in diameter and employ AlN as the piezoelectric material. The thermistors reside on top of the diaphragms and are patterned into a 100-nm-thick sputtered Pt electrode layer. Experimental characterization up to 600 °C demonstrates the importance of annealing to realize hysteresis-free resistance vs. temperature characteristics. Dynamic frequency response measurements of the pressure-sensitive diaphragms vs. temperature demonstrate a marked shift in compliance with temperature, and therefore demonstrates the importance of temperature-compensated pressure calibration in high-temperature measurement environments.