Modeling and Optimization of CMOS Compatible Various ZnO/SiO2/Si Multilayer Structure for SAW Devices Using FEM

Abstract

This article presents a design, modeling and optimization of Surface Acoustic Wave (SAW) resonator with CMOS compatible piezoelectric crystal material and characterized for wireless 915 MHz ISM frequency band. Simulation study for the realization of SAW resonator based on CMOS compatible piezoelectric thin film of Zinc oxide (ZnO) on passivated silicon (SiO2/Si) substrate is performed. The SAW properties of ZnO film on SiO2/Si were analyzed with three composite structures as (IDT)/ZnO/SiO2/Si, ZnO/(IDT)/ZnO/SiO2/Si, and ZnO/(IDT)/SiO2/Si using COMSOL Multiphysics Software. The properties of ZnO/(IDT)/SiO2/Si structure revealed good SAW properties such as maximum coupling coefficient and acoustic velocity compared to other structures. The effects of piezoelectric Zinc oxide (ZnO) layer, interdigital transducer (IDT) materials, and SiO2 thin film thickness on the evolution of the phase velocity and electromechanical coupling coefficient (K2) were studied by employing a finite element method. The design and simulations of multilayered SAW structure carried out for 915 MHz and ZnO/(IDT)/SiO2/Si structure provide excellent overall performance.