Surface acoustic wave pressure sensor on ScAlN/3C-SiC/Si layer structure incorporating biomimetic microcantilever: modelling and performance enhancement

Abstract

This paper presents a bio-inspired cantilever-type SAW pressure sensor based on Scandium-doped AlN (ScAlN)/3CSiC/Si layer structure. The proposed biomimetic microcantilever is configured with stress concentration region (SCR) comprising of a series of narrow slits. For a given depth, by properly setting the number and the width of those slits for a given depth, homogeneous stress/strain distribution in vicinity of SCR are achieved. Furthermore, multi-physics finite element modeling for evaluating the pressure coefficient of frequency (PCF) of a one-port SAW resonant sensor is performed and validated. Then the PCF for the proposed SAW pressure sensor with the optimized biomimetic microcantilever is analyzed. The dependence of ScAlN thin film thickness h ScAlN and scandium-doped concentration r of Sc r Al1-r N thin film on PCF for different SAW modes including Rayleigh mode and Sezawa mode are calculated. The investigation results show that the maximum PCF of −111 ppm bar−1 can be achieved for Rayleigh mode, which is 2.4 times larger than that of the previously reported ZnO/Si structure. In addition, its PCF has weak dependence on h ScAlN, which are quite favorable for manufacturing pressure sensors with good reproducibility. The conceived bio-inspired cantilever-type SAW devices based on ScAlN/3 CSiC/Si structure will open the door to develop pressure sensors with a stable and reliable performance and enhanced sensitivity.