Heterogeneous integration of lithium tantalate thin film on quartz for high performance surface acoustic wave resonator
Yang Chen, Jinbo Wu, Xiaomeng Zhao, Zhongxu Li, Xinjian Ke, Shibin Zhang, Min Zhou, Kai Huang, Xin Ou
Abstract
Abstract Surface acoustic wave (SAW) resonator based on the piezo film on a foreign substrate is promising to enhance the performance of radio frequency filters. In this work, the 4 inch wafer-scale lithium tantalate thin film on quartz (LTOQ) heterogenous substrate was fabricated by ion-cut process. The cut angle of quartz was optimized to achieve high-quality factor ( Q ) based on finite element analysis. The average film thickness and the film nonuniformity for the whole wafer are 602 nm and ±2.2%, respectively. The lithium tantalate film exhibits single-crystalline quality where the full width at half-maximum of high-resolution X-ray diffraction rocking curve is 47.4 arcsec. The shear horizonal surface acoustic wave resonator based on the LTOQ structure exhibits a maximum Bode- Q exceeding 3000 and the electromechanical coupling coefficient of 10.26%. The temperature coefficient of frequency at resonant frequency and anti-resonant frequency are −25.21 ppm °C −1 and −35.22 ppm °C −1 , respectively.