Use of periodically slotted SiO₂ in a layered surface acoustic wave structure for transverse mode suppression

Abstract

This work demonstrates the applicability of periodically slotted SiO2 structures (PSS) for controlling the SAW slowness shape and eliminating the transverse modes in layered SAW structures represented by I.H.P. SAW. The use of PSS comprising SiO2 blocks and air gaps provides larger acoustic anisotropy for slowness shape manipulation. The effect of PSS on transverse mode suppression are revealed. The slowness curves and frequency responses with different structural parameters of PSS are calculated by FEM analysis. Then, electrode is designed for further spurious resonances suppression. Hammer-head configuration and Si3N4 overlay are applied. It is shown that higher order transverse modes in passband were well suppressed without reduction of the electromechanical coupling factor.