An acoustic resonator includes a substrate, a center portion, an extending portion, and a barrier layer. A first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on the substrate in the central portion. The extending portion is configured to extend from the center portion, and includes an insertion layer disposed below the piezoelectric layer. The barrier layer is disposed between the first electrode and the piezoelectric layer.

A bulk acoustic wave resonator is provided. The bulk acoustic wave resonator incudes a carrier substrate, having a main surface extending along a first direction; a piezoelectric layer, located on a side of the carrier substrate in a second direction perpendicular to the main surface of the carrier substrate; a first electrode and a second electrode; a cavity boundary structure, having a body part extending along the first direction and a protruding part protruding from the body part toward the piezoelectric layer; a resonant cavity, defined by the cavity boundary structure and the piezoelectric layer; and a periphery dielectric layer, located on a side of the protruding part of the cavity boundary structure away from the resonant cavity, a material of the periphery dielectric layer is different from a material of at least a portion of the protruding part adjacent to the periphery dielectric layer.

An acoustic wave device is provided that includes a support substrate, a piezoelectric layer on the support substrate, and an interdigital transducer electrode. A ratio d/p is less than or equal to approximately 0.5, where d is a thickness of the piezoelectric layer and p is a distance between centers of adjacent electrode fingers of the multiple electrode fingers. The interdigital transducer electrode includes an intersection region in which the adjacent electrode fingers overlap when viewed in a direction in which multiple electrode fingers face each other. Moreover, two gap regions are located between the intersection region and a corresponding one of the two busbars and includes an I-B gap that is a dimension in a direction in which the multiple electrode fingers extend. The I-B gap of at least one of the two gap regions is less than or equal to about 1.1p.

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.

The present disclosure provides a bulk acoustic wave resonator comprising a piezoelectric layer and a top electrode disposed on a first surface of the piezoelectric layer. The bulk acoustic wave resonator has a central region, a first outer region, and a first raised frame region between the central region and the first outer region. The top electrode has a first thickness within the central region, a second thickness within the first raised frame region, and a third thickness within the first outer region, the second thickness being greater than both the first thickness and the third thickness. A die, filter, radio-frequency module and wireless mobile device are also provided.

A bulk acoustic wave resonator having a central region, an outer region, and a raised frame region between the central region and the outer region is disclosed. The bulk acoustic wave resonator can include a piezoelectric layer and a top electrode over the piezoelectric layer. The top electrode is disposed at least in the central region, the outer region, and the raised frame region. The top electrode is configured such that a resonant frequency in the outer region is higher than a resonant frequency in the central region.

Embodiments of this disclosure relate to bulk acoustic wave resonators on a substrate. The bulk acoustic wave resonators include a first bulk acoustic wave resonator, a second bulk acoustic wave resonator, a conductor electrically connecting the first bulk acoustic wave resonator to the second bulk acoustic wave resonator, and an air gap positioned between the conductor and a surface of the substrate.

Aspects of this disclosure relate to bulk acoustic wave devices that have a raised frame structure, and filters that utilize the bulk acoustic wave devices. The raised frame structure can include a first raised frame layer that has a relatively low acoustic impedance. The raised frame structure can include a second raised frame layer that has a relatively high acoustic impedance. The first raised frame layer can extend inward further than the second raised frame layer. A width of the first raised frame layer that overlaps the first and second electrodes is between about 1.5 times to about 4 times larger than the combined thickness of the first electrode, the piezoelectric layer, and the second electrode.

Aspects of this disclosure relate to bulk acoustic wave devices that have a raised frame structure. The raised frame structure can include a first raised frame layer that has a relatively low acoustic impedance. The raised frame structure can include a second raised frame layer that has a relatively high acoustic impedance. The first raised frame layer can have a thickness that is between about 0.02 and about 0.4 times the combined thickness H of the bulk acoustic wave device. The first raised frame layer can have a thickness that is between about 0.01 and about 0.2 times the resonant wavelength λ of the bulk acoustic wave device.

Embodiments of this disclosure relate to acoustic wave filters configured to filter radio frequency signals. An acoustic wave filter includes a first bulk acoustic wave resonator on a substrate, a second bulk acoustic wave resonator on the substrate, a conductor electrically connecting the first bulk acoustic wave resonator in anti-series with the second bulk acoustic wave resonator, and an air gap positioned between the conductor and a surface of the substrate. The air gap can reduce parasitic capacitance associated with the conductor. Acoustic wave filters disclosed herein can suppress a second harmonic.