A bulk acoustic wave filter, a manufacturing method thereof, and a communication device are disclosed. The bulk acoustic wave filter includes a first filter substrate and a second filter substrate; the first filter substrate includes a first base substrate and a first resonator, a first electrode pad and a first auxiliary pad arranged on the first base substrate; the second filter substrate includes a second base substrate and a second resonator, a second electrode pad and a second auxiliary pad arranged on the second base substrate, the first filter substrate is arranged opposite to the second filter substrate, the first electrode pad and the second auxiliary pad are in contact with each other, and the second electrode pad and the first auxiliary pad are in contact with each other.

A bulk acoustic wave filter, a manufacturing method thereof, and a communication device are disclosed. The bulk acoustic wave filter includes a first filter substrate and a second filter substrate; the first filter substrate includes a first base substrate and a first resonator, a first electrode pad and a first auxiliary pad arranged on the first base substrate; the second filter substrate includes a second base substrate and a second resonator, a second electrode pad and a second auxiliary pad arranged on the second base substrate, the first filter substrate is arranged opposite to the second filter substrate, the first electrode pad and the second auxiliary pad are in contact with each other, and the second electrode pad and the first auxiliary pad are in contact with each other.

The present disclosure provides a radio frequency filter, including: a substrate; a supporting electrode protruded on a front surface of the substrate; and a thin film structure formed on the substrate and spaced with the substrate by the supporting electrode. An end surface of a top end of the supporting electrode is in sealing contact with a front surface of the thin film structure.

A single crystal piezoelectric layer includes a first recess in a first opposing surface opposing a first main surface of a base. The single crystal piezoelectric layer is bonded to the first main surface of the base at a portion of the first opposing surface other than the first recess. A lower electrode layer defining at least a portion of a pair of electrode layers and extending over a surface of the single crystal piezoelectric layer opposing the base is at least partially located in the first recess. A second opposing surface of the lower electrode layer opposing the first main surface of the base has surface roughness greater than the surface roughness of the first opposing surface of the single crystal piezoelectric layer.

An acoustic wave device includes an IDT electrode and reflector electrodes on or above a piezoelectric substrate. A region in which first and second electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction defines an intersection region. The intersection region includes a center region and first and second edge regions on both sides of the center region. Dielectric films extend from the first and second edge regions to outer side regions in the acoustic wave propagation direction of the reflector electrodes via the reflector electrodes.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate and including electrode fingers. A portion where adjacent electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction is an intersecting region. The intersecting region includes a central region located in a central portion in a direction in which the electrode fingers extend and first and second edge regions on both sides of the central region in the direction in which the electrode fingers extend. The acoustic wave device further includes dielectric films between the piezoelectric substrate and the electrode fingers in the first and second edge regions. The dielectric films include at least one of hafnium oxide, niobium oxide, tungsten oxide, or cerium oxide.

An acoustic wave device includes an intermediate layer and a piezoelectric film that are laminated in that order on the support substrate. An interdigital transducer (IDT) electrode is provided on the piezoelectric film. Cavities are provided at least one of a location between the support substrate and the intermediate layer and a location in the intermediate layer.

A bulk-acoustic wave resonator may include: a substrate; a resonance portion; a first electrode disposed on the substrate; a piezoelectric layer disposed on the first electrode in the resonance portion; a second electrode disposed on the piezoelectric portion in the resonance portion; and a seed layer disposed in a lower portion of the first electrode. The seed layer may be formed of titanium (Ti) having a hexagonal close packed (HCP) structure, or an alloy of Ti having the HCP structure. The seed layer may have a thickness greater than or equal to 300 Å and less than or equal to 1000 Å, or may be thinner than the first electrode.

A bulk acoustic resonator architecture is fabricated by epitaxially forming a piezoelectric film on a top surface of post formed from an underlying substrate. In some cases, the acoustic resonator is fabricated to filter multiple frequencies. In some such cases, the resonator device includes two different resonator structures on a single substrate, each resonator structure configured to filter a desired frequency. Including two different acoustic resonators in a single RF acoustic resonator device enables that single device to filter two different frequencies in a relatively small footprint.

A bulk-acoustic wave resonator includes: a first electrode; a piezoelectric layer at least partially disposed on an upper portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The second electrode includes a frame disposed at an edge of an active region of the bulk-acoustic wave resonator, and the first electrode, the piezoelectric layer and the second electrode are disposed to overlap one another at the edge of the active region. The frame includes a wall disposed at the edge of the active region and a trench formed on an internal side of the wall. An internal boundary line of the trench has a concave-convex shape in a plane parallel to an upper surface of the frame.