MEMS-based Pt film temperature sensor on an alumina substrate

A Pt film temperature sensor was prepared on the alumina substrate using a microelectromechanical system (MEMS) micromachining process. The Pt sensitive element had a width of 10 μm and a thickness of 200 nm. The resistance–temperature dependence was studied in the range of 25–900 °C. The effect of the annealing temperature on the initial resistivity and temperature coefficient of resistance (TCR) of Pt film sensor was discussed. The experimental results indicated that the initial resistivity decreased with increasing the annealing temperature when it was below 700 °C, which was probably attributed to the grown grain size and the preferred orientation of (111). With the increase of annealing temperature, TCR first increased from 1.94×10−3/°C of the as-deposited film sensor to 2.40×10−3/°C of the one annealed at 800 °C, and then decreased to 2.33×10−3/°C of the one annealed at 900 °C. The absolute average deviation decreased from 26.4 °C of the as-deposited film sensor to 3.4 °C of the one annealed at 900 °C, which indicated that the film sensor showed a high accuracy after being annealed at 900 °C.