Elastic wave device and communication device

Abstract

An acoustic wave device includes a composite substrate and an excitation electrode located on an upper surface of the composite substrate. The composite substrate includes a support substrate, a multilayer film, and a piezoelectric film overlapping the upper surface of the multilayer film. The multilayer film includes a plurality of acoustic films stacked on an upper surface of the support substrate. Adjacent ones of the acoustic films in a direction in which the acoustic films are stacked are made of different materials. The excitation electrode is located on an upper surface of the piezoelectric film. A side surface of the composite substrate includes a step portion. The step portion has a step-like shape with two or more steps ascending from the support substrate side to the piezoelectric film side in a direction from an outside to an inside with respect to the side surface.

Dependencies are inferred from the claim text.