Chip-level orthometric surface acoustic wave device with AlN/metal/Si multilayer structure for sensing strain at high temperature

A new AlN film-based surface acoustic wave (SAW) device was explored for sensing strain at high tem-perature. AlN/metal/Si multilayer composite structure was proposed to construct the strain sensing chip, and the corresponding theoretical analysis on SAW propagation were performed by using finite element method (FEM). High-quality AlN piezoelectric thin-film was prepared by using magnetron sputtering on Si substrate, and Pt electrodes was then lithographically prepared to build the sensing chips with one-port resonator pattern operating at 607 MHz and 620 MHz. To compensate the temperature cross sensitivity and enhance the strain sensitivity, two sensing chips were positioned perpendicular on a ceramic package, then the differential frequency signal was extracted to evaluate the applied strain. A high-temperature strain testing platform was constructed to characterize the prepared strain sensor with orthometric structure, larger strain sensitivity of 0.84 ppm/mu epsilon at 550 degrees C in the range 0 - 500 mu epsilon and excellent temperature stability of 0.624 ppm/degrees C at the temperature range of 20-600 degrees C were achieved successfully. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A new AlN film-based surface acoustic wave (SAW) sensor was developed for high-temperature strain detection, with improved strain sensitivity achieved through differential frequency signal extraction. The sensor demonstrated a maximum sensitivity of 0.84 ppm/mu epsilon at 550 degrees C and excellent temperature stability in the range of 20-600 degrees C.