A resonator circuit device. The present invention provides for improved resonator shapes using egg-shaped, partial egg-shaped, and asymmetrical partial egg-shaped resonator structures. These resonator shapes are configured to give less spurious mode/noise below the resonant frequency (F.sub.s) than rectangular, circular, and elliptical resonator shapes. These improved resonator shapes also provide filter layout flexibility, which allows for more compact resonator devices compared to resonator devices using conventionally shaped resonators.

A bulk-acoustic wave resonator comprises a substrate, a resonant portion comprising a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, and further comprising a center portion and an extension portion that is disposed along a periphery of the center portion, and an insertion layer that is disposed in the extension portion between the first electrode and the piezoelectric layer, and the insertion layer is formed of an aluminum alloy containing scandium (Sc).

A method of forming a resonator structure can be provided by forming one or more template layers on a substrate, (a) epitaxially forming an AlScN layer on the template layer to a first thickness, (b) epitaxially forming an AlGaN interlayer on the AlScN layer to a second thickness that is substantially less than the first thickness, and repeating operations (a) and (b) until a total thickness of all AlScN layers and AlGaN interlayers provides a target thickness for a single crystal AlScN/AlGaN superlattice resonator structure on the template layer.

A bulk acoustic wave resonator includes a substrate, and a stack that is supported by the substrate. The stack includes a first electrode, a multilayer buffer, a piezoelectric layer, and a second electrode. The multilayer buffer is disposed between the first electrode and the piezoelectric layer, and the piezoelectric layer is disposed between the multilayer buffer and the second electrode. The multilayer buffer includes two or more pairs of alternating layers. A first pair of the two or more pairs include a first layer of crystalline material having a first lattice constant, and a second layer of crystalline material having a lattice constant that is distinct from the first lattice constant.

A BAW resonance device comprises a first layer including a cavity located on a first side, a first electrode having a first end located in the cavity and a second end contacting with the first layer, a second layer located on the first side, and a second electrode located on the second layer above the cavity, wherein the first electrode and the second electrode are located on two sides of the second layer. The first electrode comprises a first electrode layer and a second electrode layer, and the second electrode layer and the second layer are located on two sides of the first electrode layer. The second electrode comprises a third electrode layer and a fourth electrode layer, and the second layer and the fourth electrode layer are located on two sides of the third electrode layer. Thus, the electrical resistance is lowered and the electrical losses are reduced.

An acoustic wave device includes: a substrate; a first electrode on the substrate; a piezoelectric layer on the first electrode; and a second electrode on the piezoelectric layer. A bonding interface is located between the substrate and the first electrode. The full width at half maximum (FWHM) in the X-ray diffraction pattern of the crystal plane <002> of the piezoelectric layer is between 10 arc-sec and 3600 arc-sec.

Filter devices are disclosed. A filter device includes a piezoelectric plate comprising a supported portion, a first diaphragm, and a second diaphragm. The supported portion is attached to a substrate and the first and second diaphragms spans respective cavities in the substrate. A first interdigital transducer (IDT) has interleaved fingers on the first diaphragm. A second interdigital transducer (IDT) has interleaved fingers on the second diaphragm. A first dielectric layer is between the interleaved fingers of the first IDT, and a second dielectric layer is between the interleaved fingers of the second IDT. A thickness of the first dielectric layer is greater than a thickness of the second dielectric layer. The piezoelectric plate and the first and second IDTs are configured such that radio frequency signals applied to first and second IDTs excite primary shear acoustic modes in the respective diaphragms.

Piston mode Lamb wave resonators are disclosed. A piston mode Lamb wave resonator can include a piezoelectric layer, such as an aluminum nitride layer, and an interdigital transducer on the piezoelectric layer. The piston mode Lamb wave resonator has an active region and a border region, in which the border region has a velocity with a lower magnitude than a velocity of the active region. The border region can suppress a transverse mode.

Methods of fabricating resonator and filter devices. A first conductor pattern formed on a front surface of a piezoelectric plate includes a first plurality of contact pads and an interdigital transducer (IDT). The IDT and the piezoelectric plate are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode within the piezoelectric plate. An acoustic Bragg reflector is between a substrate and a back surface of the piezoelectric plate, the acoustic Bragg reflector configured to reflect the shear primary acoustic mode. A second conductor pattern including a second plurality of contact pads is formed on a back surface of the interposer. The first plurality of contact pads is directly connected to respective contact pads of the second plurality of contact pads. A perimeter of the acoustic resonator chip is sealed to a perimeter of the interposer.

Provided is a laminate including: a substrate 210, an electrode layer 230 disposed on or above the substrate 210 and having a single-crystalline structure containing a metal element; a buffer layer 220 formed between the substrate 210 and the electrode layer 230 and configured to improve crystal orientation of the electrode layer 230; and a piezoelectric layer 240 formed on the electrode layer 230 and made of a piezoelectric body. Each of the buffer layer 220 and the piezoelectric layer 240 has a single-crystalline structure based on a composition of either ScAlN or AlN.