Provided is a bulk acoustic wave resonator (BAWR). The BAWR may include an air cavity disposed on a substrate, a bulk acoustic wave resonant unit including a piezoelectric layer, and a reflective layer to reflect a wave of a resonant frequency that is generated from the piezoelectric layer.

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.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a support substrate, a solid acoustic mirror on the support substrate, a piezoelectric layer on the solid acoustic mirror, and an interdigital transducer electrode on the piezoelectric layer. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave.

A BAW resonator is provided wherein the top electrode (TE) has an outer flap (OF). The flap extends away from the active resonator region (AR) and has a projecting section that runs at a level above the piezoelectric layer (PL) that is higher than the level of the top electrode at any of the inwardly located areas enclosed by the outer flap. The higher level is formed by an intermediate step-forming material (SM) arranged between piezoelectric layer and top electrode in the outer flap. The step forming material comprises a structured layer of an acoustic impedance that is low w.r.t. the impedance of the top electrode and the piezoelectric layer.

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.

Acoustic resonator devices, filter devices, and methods of fabrication are disclosed. A resonator device includes a single-crystal piezoelectric plate having a front surface and a back surface opposite the front surface, wherein the back surface is coupled to a surface of a substrate. A floating back-side conductor pattern is formed on a portion of the back surface. A front-side conductor pattern including two electrodes is formed on a portion of the front surface opposite the back-side conductor.

A bulk acoustic wave resonator with better performance and better manufacturability is described. The bulk acoustic wave resonator includes a composite piezoelectric film. The composite piezoelectric film includes a first sublayer of a first piezoelectric material, a second sublayer of a second piezoelectric material, and a third sublayer of a third piezoelectric material that is disposed between the first sublayer and the second sublayer. The first piezoelectric material has a first lattice constant, the second piezoelectric material has a second lattice constant, and the third piezoelectric material has a third lattice constant that is distinct from the first lattice constant and from the second lattice constant. The composite piezoelectric film may include a sequence of alternating sublayers of two or more distinct piezoelectric materials, or a sequence of composition graded layers having gradually changing composition.

A bulk acoustic (BAW) resonator having a multilayer base and method of fabricating the bulk acoustic resonator is disclosed. A BAW resonator comprises a substrate having a cavity and including a frame around the cavity, a multilayer base adjacent the cavity and supported by the frame. The multilayer base includes a first layer of crystalline material having a first lattice constant and a second layer of crystalline material having a second lattice constant that is distinct from the first lattice constant. The BAW resonator further includes a stack over the multilayer base. The stack includes a first electrode formed on the multilayer base, a piezoelectric layer having a first side coupled to the first electrode and a second side opposite to the first side of the piezoelectric layer, and a second electrode coupled to the second side of the piezoelectric layer.

A bulk acoustic wave (BAW) resonator with better performance and better manufacturability is described. A BAW resonator includes a substrate, a BAW stack disposed over the substrate, a first temperature compensation layer disposed between the substrate and the stack, and a second temperature compensation layer disposed over the stack. The BAW stack includes a piezoelectric layer disposed between a first electrode and a second electrode. A method of making a BAW resonator is also disclosed. The method includes forming a first base layer over a substrate including a layer of sacrificial material and a frame surrounding the layer of sacrificial material, forming a first temperature compensation layer over the first base layer, forming a BAW stack over the first temperature compensation layer, forming a second temperature compensation layer over the BAW stack, and removing the layer of sacrificial material to form a cavity adjacent the base layer.

A bulk acoustic wave (BAW) resonator includes a substrate, a stack over the substrate and including a piezoelectric layer disposed between two electrode layers, and one or more edge frames. The one or more edge frames can be a raised metal frame extending parallel to a periphery of an active region of the stack and has one or more slanted cuts such that the edge frame does not form a closed loop and loss of acoustic energy in the active region through the one or more cuts is reduced, minimized or prevented. Alternatively or additionally, the one or more edge frames include a recessed edge frame in the form of a trench in the piezoelectric layer extending parallel to a boundary of the active region, and may further include a second edge frame formed on the first electrode and embedded in the piezoelectric layer.