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.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.

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.

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.

A bulk acoustic resonator operable in a bulk acoustic mode includes a resonator body mounted to a separate carrier that is not part of the resonator body. The resonator body includes a piezoelectric layer, a device layer, and a top conductive layer on the piezoelectric layer opposite the device layer. A surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to the carrier.

The invention provides a filter device, an RF front-end device and a wireless communication device. The filter device comprises a substrate, at least one resonance device, a passive device and a connector, wherein the at least one resonance device has a first side and a second side opposite to the first side, the substrate is located on the first side, and the passive device is located on the second side. The at least one resonance device is connected to the passive device through the connector. The RF filter device formed by integrating the resonance device (such as an SAW resonance device or a BAW resonance device) and the passive device (such as an IPD) in one die can broaden the passband width, has a high out-of-band rejection, and occupies less space in an RF front-end chip.

An acoustic wave device includes a support substrate, a piezoelectric film on the support substrate, and an IDT electrode on the piezoelectric film. A film thickness of the piezoelectric film is equal to or less than about 1λ when λ is a wavelength of an acoustic wave determined by an electrode finger period of the IDT electrode. The piezoelectric film includes first and second regions in a thickness direction of the piezoelectric film. A first density that is a density in the first region and a second density that is a density in the second region are different from each other.

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.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0°], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.