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.

A method for forming a bulk acoustic wave resonance device is provided, includes: forming a first stack, and said forming the first stack includes providing a first substrate; forming a piezoelectric layer on the first substrate; forming a first electrode layer on the piezoelectric layer; forming a cavity preprocessing layer on the piezoelectric layer, and a cavity is to be formed based on the cavity preprocessing layer, the cavity preprocessing layer at least covers a first end of the first electrode layer, and the cavity preprocessing layer is in contact with the piezoelectric layer, a first side of the first stack corresponds to a side of the first substrate, and a second side of the first stack corresponds to a side of the cavity preprocessing layer; forming a second stack, and said forming the second stack includes providing a second substrate; joining the first stack and the second stack, and the second stack is disposed at the second side; removing the first substrate, and the first side corresponds to a side of the piezoelectric layer; forming a second electrode layer at the first side, and the second electrode layer is in contact with the piezoelectric layer; and removing the second stack.

A method of manufacturing an acoustic wave device is disclosed. The method includes attaching a support layer to a ceramic layer. The support layer has a higher thermal conductivity than the ceramic layer. The ceramic layer can be a polycrystalline spinel layer. The method also includes bonding a piezoelectric layer to a surface of the ceramic layer. The method further includes forming an interdigital transducer electrode over the piezoelectric layer.

An acoustic wave device includes a support, a piezoelectric layer on the support, a functional electrode at the piezoelectric layer, a frame-shaped support frame on the piezoelectric layer and surrounding the functional electrode in plan view in a stacking direction of the support and the piezoelectric layer, and a lid covering an opening of the support frame, wherein the support includes a first cavity overlapping at least a portion of the functional electrode in the plan view, a second cavity defined by the piezoelectric layer, the support frame, and the lid between the piezoelectric layer and the lid, the piezoelectric layer includes a through hole communicating with the first and second cavities, and a gas is provided in the first and second cavities.

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 an IDT electrode with an inclined IDT structure on a piezoelectric substrate. An intersection region, where a first electrode finger and a second electrode finger overlap each other when viewed in an acoustic wave propagation direction, includes a central region and first and second low acoustic velocity regions on both sides of the central region. The first and second low acoustic velocity regions have an asymmetric shape about a central axis extending in a length direction of the first and second electrode fingers.

Aspects of acoustic resonators and methods of manufacture of acoustic resonators are described, including acoustic resonators with thinner layers of piezoelectric material. In one example, a method of manufacturing an acoustic resonator includes providing a substrate, depositing a layer of piezoelectric material over the substrate by atomic layer deposition (ALD), and forming an electrode in contact with the layer of piezoelectric material. ALD is used to deposit highly uniform and conformal thin films of piezoelectric material and, in some cases, electrodes and encapsulation layers. The acoustic resonators described herein are better suited for the demands of new radio frequency (RF) filters, duplexers, transformers, and other components in front-end radio electronics and other applications.

Harmonic suppression in bulk acoustic wave duplexer. In some embodiments, a filter circuit can include an input node and an output node, and a first assembly having one or more bulk acoustic wave (BAW) resonators implemented electrically between the input node and the output node, and configured to filter a signal. The filter circuit can further include a second assembly having one or more surface acoustic wave (SAW) resonators implemented electrically relative to the first assembly, and configured to suppress one or more harmonics resulting from the filtering of the signal by the first assembly.

A filter includes a piezoelectric film, an acoustic wave resonator including a functional electrode on the piezoelectric film, a capacitor connected in parallel to the acoustic wave resonator, and a resonator electrically connected to the acoustic wave resonator. The functional electrode includes first and second busbars facing each other and first and second electrodes respectively connected to the first and second busbars. The filter further includes a connection electrode on the piezoelectric film and electrically connecting the capacitor and the second busbar to each other. The capacitor includes the first busbar, an insulation film on the first busbar, and a capacitance electrode on the insulation film and that is electrically insulated from the first busbar.