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

摘要

Surface acoustic wave devices based on LiNbO$_{3} /$ interlayer/substrate layered structure have attracted great attention due to the high electromechanical coupling coefficient $(mathrm{K}^{2})$ of LiNbO3 and the energy confinement effect of the layered structure. In this study, 30° YX-LiNbO3 (LN)/SiO$_{2} /$Si multilayered structure, which can excited shear-horizontal surface acoustic wave (SH-SAW) with high $mathrm{K}^{2}$, was proposed. The optimized orientation of LiNbO3 was verified by the effective permittivity method based on the stiffness matrix. The phase velocity, $mathrm{K}^{2}$ value, and temperature coefficient of frequency (TCF) of the SH-SAW were calculated as a function of the LiNbO3 thickness at different thicknesses of the SiO2 in 30° YX-LiNbO$_{3} /SiO_{2} /$Si multilayer structure by finite element method (FEM). The results show that the optimized LiNbO3 thickness is 0.1 and the optimized SiO2 thickness is 0.2$lambda$. The optimized Al electrode thickness and metallization ratio are 0.07 and 0.4, respectively. The $mathrm{K}^{2}$ of the SH-SAW is 29.89%, the corresponding phase velocity is 3624.00 m/s and TCF is about 10 ppm$/^{circ}mathrm{C}$ with the optimized IDT$/ 30^{circ}$ YX-LiNbO$_{3} /SiO_{2} /$Si layered structure.