Design of high-frequency surface acoustic wave resonator based on IDT/etched-AlN/IDT/AlN/diamond multilayer structure

This study presents a high-frequency surface acoustic wave (SAW) resonator based on interdigital transducers (IDT)/etched aluminum nitride (AlN)/IDT/AlN/diamond multilayer structure. Through COMSOL simulations, the influence laws of the piezoelectric layer thickness, the position of the second electrode, and the electrode thickness on the device's phase velocity (Vp), electromechanical coupling coefficient (K2), and quality factor (Q) are systematically analyzed. The results show that the multi-layer structure significantly enhances energy localization efficiency through a dual-IDT coupling mechanism, achieving a Vp of 11210 m/s compared to a traditional etched AlN structure. The K2 is elevated to 3.09%, and the Q value reaches 2480. The optimized resonator achieves a quality factor figure of merit (FOM) of 76.6 at a frequency of 5.57 GHz, with comprehensive performance surpassing that of existing AlN/diamond-based SAW devices. This research presents a high-frequency SAW device design scheme applicable to fields such as 5G communications and high-frequency signal processing.