Vertically-Excited High-Order Guided Shear Vertical Surface Acoustic Wave Resonators for 5G and Beyond

This work reports novel solidly mounted acoustic resonators based on the high-order guided shear vertical surface acoustic wave (SV-SAW) mode. The design utilizes a high-velocity supporting substrate to suppress the leakage of the main mode, while incorporating a bottom electrode to establish a vertical electric field for acoustic wave excitation. Using the finite element method (FEM), structural parameters were optimized to achieve a resonator with large electromechanical coupling coefficient (${k}_{t}^{2}$), low loss, and weak spurious modes simultaneously. The layout and dimensions of the bottom electrode are optimized to minimize bulk acoustic wave leakage. Subsequently, two specifications of resonators based on X-cut LiNbO3/patterned metal/SiO2/SiC substrate were fabricated via a secondary transfer process of piezoelectric single-crystal film. The fabricated resonators aiming at the C-band exhibit${k}_{t}^{2}$ranging from 6% to 16%. Resonators operating at higher frequencies near 9 GHz were also fabricated, achieving$k_{t}^{2}$value up to 16%. With further optimization, this novel high-order guided SV-SAW resonator will offer a promising filtering solution for 5G New Radio (NR) and future 6G.[2025-0194]