A bonded body includes a supporting substrate and piezoelectric material layer. The supporting substrate is composed of sialon. The material of the piezoelectric material layer is LiAO.sub.3 (A represents one or more element selected from the group consisting of niobium and tantalum). It is included an interface layer present along an interface between the supporting body and piezoelectric material layer and a supporting substrate-side intermediate layer present between the interface layer and supporting substrate. Each of the interface layer and supporting substrate-side intermediate layer contains nitrogen, oxygen, aluminum, silicon and one or more element selected from the group consisting of niobium and tantalum as main components.

An acoustic wave device includes a piezoelectric substrate made of LiNbO.sub.3 or LiTaO.sub.3 and including first and second main surfaces that face each other, a functional electrode provided on the first main surface of the piezoelectric substrate to excite acoustic waves, and a Li.sub.2CO.sub.3 layer provided on the second main surface of the piezoelectric substrate.

An acoustic wave device includes a support substrate including a main surface including first and second regions adjacent to each other in a plan view; a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; an IDT electrode on the piezoelectric layer of the multilayer body; and an insulating film in the second region of the support substrate to cover the side surface of the multilayer body. An angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film.

Of a plurality of acoustic wave resonators, the acoustic wave resonator electrically closest to a first terminal is an antenna end resonator, the antenna end resonator is a first acoustic wave resonator and at least one acoustic wave resonator other than the antenna end resonator of the plurality of acoustic wave resonators is a second acoustic wave resonator. An acoustic wave device satisfies a first condition. The first condition is a condition that a high acoustic velocity layer of the first acoustic wave resonator and a high acoustic velocity layer of the second acoustic wave resonator each include a silicon substrate, a surface closer to a piezoelectric layer in the silicon substrate of the first acoustic wave resonator is a plane or a plane, and a surface closer to a piezoelectric layer in the silicon substrate of the second acoustic wave resonator is a plane.

An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

An electronic component including a pad electrode provided on a wiring electrode and a Au bump provided on the pad electrode, wherein the uppermost layer of the wiring electrode is a first Ti layer, the uppermost layer of the pad electrode is a Au layer, and the thickness of the first Ti layer in at least a portion on which the Au bump is superposed in plan view is greater than the thickness of at least a portion of the first Ti layer in a portion on which the Au bump is not superposed in plan view.

It is proposed a bonded body having a supporting substrate and piezoelectric material layer. The supporting substrate is composed of mullite, and the material of the piezoelectric material layer is LiAO.sub.3 (A represents one or more element selected from the group consisting of niobium and tantalum). It is included an interface layer present along an interface between the supporting body and piezoelectric material layer and a supporting substrate-side intermediate layer present between the interface layer and supporting substrate. Each of the interface layer and supporting substrate-side intermediate layer contains oxygen, aluminum, silicon and one or more element selected from the group consisting of niobium and tantalum as main components.

A bonded body includes a supporting substrate and piezoelectric material layer. The supporting substrate is composed of sialon. The material of the piezoelectric material layer is LiAO.sub.3 (A represents one or more element selected from the group consisting of niobium and tantalum). It is included an interface layer present along an interface between the supporting body and piezoelectric material layer and a supporting substrate-side intermediate layer present between the interface layer and supporting substrate. Each of the interface layer and supporting substrate-side intermediate layer contains nitrogen, oxygen, aluminum, silicon and one or more element selected from the group consisting of niobium and tantalum as main components.

An elastic wave device includes a lamination layer film including a piezoelectric thin film on a support substrate. The lamination layer film is not partially present in a region located in an outer side portion of a region where IDT electrodes are provided. A first insulation layer extends from at least a portion of a region where the lamination layer film is not present to an upper portion of the piezoelectric thin film. A wiring electrode extends from the upper portion of the piezoelectric thin film to an upper portion of the first insulation layer, and extends onto a section of the first insulation layer in the region.

An elastic wave device includes a lamination layer film including a piezoelectric thin film on a support substrate. The lamination layer film is not partially present in a region located in an outer side portion of a region where IDT electrodes are provided. A first insulation layer extends from at least a portion of a region where the lamination layer film is not present to an upper portion of the piezoelectric thin film. A wiring electrode has a width of about 6 m and extends from the upper portion of the piezoelectric thin film to an upper portion of the first insulation layer, and extends onto a section of the first insulation layer in the region.