Acoustic wave device

Abstract

An acoustic wave device includes a support substrate, an intermediate layer on the support substrate, a piezoelectric layer on the intermediate layer, and an IDT electrode on the piezoelectric layer and including a plurality of electrode fingers. When a thickness of a portion of the piezoelectric layer in which the IDT electrode is provided is d, and a distance between centers of adjacent electrode fingers is p, d/p is about 0.5 or smaller. A cavity is between the piezoelectric layer and the support substrate, and overlaps with the IDT electrode in plan view. The acoustic wave device further includes one of a silicon nitride film, an amorphous silicon film, or a polycrystalline silicon film each including at least a portion provided between the support substrate and the intermediate layer and each facing the piezoelectric layer with at least one of the cavity and the intermediate layer therebetween.

Dependencies are inferred from the claim text.