Theorectical Optimazation of Surface Acoustic Waves Resonator Based on 30^° Y-Cut Linbo3/SIO2/SI Multilayered Structure

Surface acoustic wave devices based on LiNbO ₃ /interlayer/substrate layered structure have attracted great attention due to the high electromechanical coupling coefficient (K ² ) of LiNbO ₃ and the energy confinement effect of the layered structure. In this study, 30° YX-LiNbO ₃ (LN)/SiO ₂ /Si multilayered structure, which can excited shear-horizontal surface acoustic wave (SH-SAW) with high K ² , was proposed. The optimized orientation of LiNbO ₃ was verified by the effective permittivity method based on the stiffness matrix. The phase velocity, K ² value, and temperature coefficient of frequency (TCF) of the SH-SAW were calculated as a function of the LiNbO ₃ thickness at different thicknesses of the SiO ₂ in 30° YX-LiNbO ₃ /SiO ₂ /Si multilayer structure by finite element method (FEM). The results show that the optimized LiNbO ₃ thickness is 0.1 and the optimized SiO ₂ thickness is 0.2λ. The optimized Al electrode thickness and metallization ratio are 0.07 and 0.4, respectively. The K ² of the SH-SAW is 29.89%, the corresponding phase velocity is 3624.00 m/s and TCF is about 10 ppm/°C with the optimized IDT/30° YX-LiNbO ₃ /SiO ₂ /Si layered structure.