Surface acoustic wave temperature sensor based on Pt/AlN/4 H-SiC structure for high-temperature environments

In this study, a two-dimensional finite element model (2D-FEM) of surface acoustic wave sensors based on Pt/ AlN/SiC structure was first constructed using the commercial software COMSOL Multiphysics. The hightemperature performance of SAW temperature sensors based on this structure was predicted by simulations. To improve the accuracy of the simulation, a set of pre-validated physical constants of both AlN and SiC were considered. And the relevant temperature coefficients of each layer of material were quoted. Following this, the fabrication of the SAW resonator was completed by the MEMS fabrication process. In order to measure the hightemperature performance of the SAW sensor, a specific probe station was established to make effective measurements from room temperature to 800 degrees C. The results show that the response of the SAW resonator is well linear with respect to temperature and it exhibits good stability. The temperature coefficient of frequency (TCF) was measured to be approximately - 25.9 ppm/degrees C, which is approximately consistent with the simulation results.