An acoustic wave device includes a piezoelectric film and an IDT electrode on the piezoelectric film. The IDT electrode includes first and second busbars, at least one first electrode finger, and at least one second electrode finger. When an overlap region is defined as a region in which the first and second electrode fingers overlap each other in an acoustic wave propagation direction, points A2, B2, C2, and D2, defined as follows, are all outside the cavity when, at the points A2, B2, C2, and D2, xa>about 25 μm, ya>about 25 μm, xb>about 25 μm, yb>about 25 μm, xc>about 25 μm, yc>about 25 μm, xd>about 25 μm, and yd>about 25 μm.

An acoustic wave device assembly is disclosed. The acoustic wave device assembly can include a first acoustic wave device that includes a first substrate, a first piezoelectric layer, a first solid acoustic mirror that is disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode that has a first portion embedded in the first piezoelectric layer and a second portion disposed over a surface of the first piezoelectric layer. The acoustic wave device assembly can include a second acoustic wave device that includes a second substrate, a second piezoelectric layer, a second solid acoustic mirror that is disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode that is in contact with the second piezoelectric layer. The second acoustic wave device is stacked over the first acoustic wave device. The first acoustic wave device and the second acoustic wave device are spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, a functional electrode on the piezoelectric layer, first and second electrode films on the piezoelectric layer, facing each other, and having different electric potentials from each other, and a dielectric film between at least one of at least a portion of the first electrode film and the piezoelectric layer and at least a portion of the second electrode film and the piezoelectric layer.

An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, a functional electrode on the piezoelectric layer, and first and second electrode films on the piezoelectric layer, facing each other, and having different electric potentials from each other. When a region between the first and second electrode films in a plan view is an inter-electrode film region, and a region overlapping with the first electrode film or the second electrode film in a plan view is an electrode film underlying region, a thickness of the piezoelectric layer in at least a portion of the inter-electrode film region is smaller than a thickness of the piezoelectric layer in the electrode film underlying region.

An acoustic wave device includes a piezoelectric substrate, and an IDT electrode on the piezoelectric substrate, and the IDT electrode includes an intersection region in which first and second electrode fingers overlap each other in an acoustic wave propagation direction, the intersection region includes a central region and first and second low acoustic velocity regions outside the central region on respective sides in an extending direction of the first and second electrode fingers, first and second busbars include first and second cavities, respectively, first and second inner busbar portions on one side of the first and second cavities, and first and second outer busbar portions on another side are connected by first and second connecting portions, and at least one of the first connecting portions and at least one of the second connecting portions are a first wide width connecting portion and a second wide width connecting portion having a width wider than that of each of remaining first and second connecting portions.

An acoustic wave device includes a piezoelectric layer made of one of lithium niobate or lithium tantalate and including first and second main surfaces, and first and second electrode fingers on the first main surface of the piezoelectric layer. The first and second electrode fingers are adjacent electrodes. When a center thickness of the piezoelectric layer in a region between the first and second electrode fingers is denoted by t.sub.p1, and a center-to-center distance between the first and second electrode fingers is denoted by p, t.sub.p1/p is about 0.5 or less. When a thickness of the piezoelectric layer in a region where the first electrode finger is located is denoted by t.sub.p2, t.sub.p1 > t.sub.p2.

An elastic wave device in which an IDT electrode defines an excitation electrode on a piezoelectric layer, an acoustic reflection layer is laminated on a first main surface of the piezoelectric layer, the acoustic reflection layer includes high acoustic impedance layers with a relatively high acoustic impedance and low acoustic impedance layers with a relatively low acoustic impedance, and the acoustic reflection layer has an unwanted wave reflection suppression structure in which reflection of unwanted waves toward the piezoelectric layer side is significantly reduced or prevented.

A resonance apparatus that processes an electrical loss using a conductive material and a method of manufacturing the resonance apparatus are provided. The resonance apparatus includes a lower electrode formed at a predetermined distance from a substrate, and a piezoelectric layer formed on the lower electrode. The resonance apparatus further includes an upper electrode formed on the piezoelectric layer, and a conductive layer formed on the upper electrode or the lower electrode.

Aspects of this disclosure relate to a bulk acoustic wave device with a floating raised frame structure. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a floating raised frame structure positioned on a same side of the piezoelectric layer as the first electrode and spaced apart from the first electrode. The floating raised frame structure is at a floating potential. The bulk acoustic wave device can suppress a raised frame mode. Related methods, filters, multiplexers, radio frequency front ends, radio frequency modules, and wireless communication devices are disclosed.

A film bulk acoustic wave resonator (FBAR) includes a piezoelectric film disposed in a central region defining a main active domain in which a main acoustic wave is generated during operation, and in recessed frame regions disposed laterally on opposite sides of the central region. The piezoelectric film disposed in the recessed frame regions includes a greater concentration of defects than a concentration of defects in the piezoelectric film disposed in the central region.