Wafer bonding of polycrystalline spinel with LiNbO<inf>3</inf>/LiTaO<inf>3</inf> for temperature compensation of RF surface acoustic wave devices

Abstract

This paper proposes use of polycrystalline spinel for the temperature compensation of RF surface acoustic wave (SAW) devices. Spinel can be bonded with LiTaO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LT) and LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LN) wafers by using adhesive and direct bonding techniques. A series of RF SAW resonators were fabricated on the LT(LN)/spinel structure, and their performance including the temperature coefficient of frequency (TCF) was measured. For comparison, SAW resonators employing Si, sapphire and alumina in place of spinel were also fabricated. The result indicated that the polycrystalline spinel offers TCF improvement better than the other materials.