The present disclosure provides a bulk acoustic wave resonator and an electronic device, and belongs to the field of communication technology. The bulk acoustic wave resonator of the present disclosure includes: a base substrate, a first electrode, a piezoelectric layer, and a second electrode; the first electrode is on the base substrate, the second electrode is on a side of the first electrode away from the base substrate, the piezoelectric layer is between the first electrode and the second electrode; and orthographic projections of any two of the first electrode, the piezoelectric layer and the second electrode on the base substrate at least partially overlap with each other; wherein the bulk acoustic wave resonator further includes: a first heat conduction layer on a side of the first electrode close to the base substrate.

A method for transferring a piezoelectric layer onto a support substrate comprises: providing a donor substrate including a heterostructure comprising a piezoelectric substrate bonded to a handling substrate, and a polymerized adhesive layer at the interface between the piezoelectric substrate and the handling substrate, forming a weakened zone in the piezoelectric substrate, so as to delimit the piezoelectric layer to be transferred, providing the support substrate, forming a dielectric layer on a main face of the support substrate and/or of the piezoelectric substrate, bonding the donor substrate to the support substrate, the dielectric layer being at the bonding interface, andfracturing and separating the donor substrate along the weakened zone at a temperature below or equal to 300 C.

A composite substrate includes in this order: a piezoelectric layer; a reflective layer including a low-impedance layer containing silicon oxide and a high-impedance layer; and a support substrate. The low-impedance layer has a density of 2.4 g/cm.sup.3 or less. The high-impedance layer has formed therein an amorphous region.

The present invention relates to a BAW filter operating with bulk acoustic waves, which has a multilayer construction, wherein functional layers of a BAW resonator operating with bulk acoustic waves are realized by the multilayer construction, and wherein an interconnection of passive components is furthermore formed by the multilayer construction, said interconnection forming a balun, wherein the balun has at least one inductance (L1, L2, L3) and at least one capacitance (C1, C2) which are formed from structured functional layers of the BAW resonator. Furthermore, the invention relates to a method for producing the BAW filter.

Embodiments of a Bulk Acoustic Wave (BAW) resonator in which an outer region of the BAW resonator is engineered in such a manner that lateral leakage of mechanical energy from an active region of the BAW resonator is reduced, and methods of fabrication thereof, are disclosed. In some embodiments, a BAW resonator includes a piezoelectric layer, a first electrode on a first surface of the piezoelectric layer, a second electrode on a second surface of the piezoelectric layer opposite the first electrode, and a passivation layer on a surface of the second electrode opposite the piezoelectric layer, the passivation layer having a thickness (T.sub.PA). The BAW resonator also includes a material on the second surface of the piezoelectric layer adjacent to the second electrode in an outer region of the BAW resonator. The additional material has a thickness that is n times the thickness (T.sub.PA) of the passivation layer.

In a method of manufacturing a piezoelectric device in which a piezoelectric thin film on which functional conductors are formed is fixed to a support substrate by a fixing layer, an alignment mark is formed on one main surface of a light-transmitting piezoelectric substrate. A sacrificial layer is formed on a main surface of the piezoelectric substrate with reference to the alignment mark and the fixing layer is formed so as to cover the sacrificial layer and is bonded to the support substrate. The piezoelectric thin film is formed by being separated from the piezoelectric substrate and the functional conductors are formed on the surface of the piezoelectric thin film with reference to the alignment mark. The piezoelectric device is able to be manufactured while positions of formation regions of conductors are adjusted efficiently.

Bulk Acoustic Wave (BAW) resonators that include a modified outside stack portion and methods for fabricating such BAW resonators are provided. One BAW resonator includes a reflector, a bottom electrode, a piezoelectric layer, and a top electrode. An active region is formed where the top electrode overlaps the bottom electrode and an outside region surrounds the active region. The piezoelectric layer includes a top surface adjacent to the top electrode and a bottom surface adjacent to the bottom electrode. The piezoelectric layer further includes an outside piezoelectric portion in the outside region with a bottom surface in the outside region that is an extension of the bottom surface of the piezoelectric layer, and the outside piezoelectric portion includes an angled sidewall that resides in the outside region and extends from the top surface of the piezoelectric layer to the bottom surface of the outside piezoelectric portion in the outside region.

A method is provided for fabricating a bulk acoustic wave (BAW) resonator device. The method includes forming an etch stop layer over a bottom electrode and a substrate; forming a dielectric layer on the etch stop layer; forming a photomask over the dielectric layer defining an opening over the bottom electrode; etching a portion the dielectric layer through the opening of the photomask to the etch stop layer to create a corresponding opening in the dielectric layer; removing the photomask, leaving un-etched protruding portions of the dielectric layer around the opening in the dielectric layer; and removing the protruding portions of the dielectric layer, a portion of the etch stop layer located over the bottom electrode, and a minimal portion of the bottom electrode to provide a planarized surface including a top surface of the bottom electrode and an adjacent top surface of the dielectric layer deposited over the substrate.

An acoustic resonator is fabricated with a substrate having a substrate top surface and a piezoelectric plate having plate front and plate back surfaces. An acoustic Bragg reflector is sandwiched between the substrate top surface and the plate back surface. The reflector has a cavity with a top surface perimeter, and the acoustic Bragg reflector is configured to reflect shear acoustic waves at a resonance frequency of the acoustic resonator. The back surface is mounted on the cavity top surface perimeter except for a portion of the plate forming a diaphragm that spans the cavity. An interdigital transducer (IDT) is formed on the plate front surface such that interleaved fingers of the IDT are disposed on the diaphragm. Two or more layers of the acoustic Bragg reflector form pedestals that support the back surface of the plate opposite some or all interleaved fingers of the IDT.

An RF filter system includes a plurality of bulk acoustic wave resonators arranged in a circuit having serial and parallel shunt configurations of resonators. Each resonator having a reflector, a support member including a surface, a first electrode including tungsten, overlying the reflector, a piezoelectric film including crystalline aluminum scandium nitride overlapping the first electrode, a second electrode including tungsten overlapping the piezoelectric film and the first electrode, and a passivation layer including silicon nitride overlying the second electrode. Portions of the support member surface of at least one resonator define a cavity region having a portion of the first electrode of the at least one resonator is located within the cavity region. The pass band circuit response has a bandwidth corresponding to a thickness of at least one of the first electrode, piezoelectric film, second electrode, and passivation layer. The system can include single crystal or polycrystalline BAW resonators.