A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. Patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the electrodes and a planarized support layer is deposited over the sacrificial layer. The device can include temperature compensation layers (TCL) that improve the device TCF. These layers can be thin layers of oxide type materials and can be configured between the top electrode and the piezoelectric layer, between the bottom electrode and the piezoelectric layer, between two or more piezoelectric layers, and any combination thereof. In an example, the TCLs can be configured from thick passivation layers overlying the top electrode and/or underlying the bottom electrode.

An AT-cut crystal resonator plate includes: a vibrating part having a rectangular shape in plan view that is disposed on a center of the AT-cut crystal resonator plate and that has excitation electrodes respectively formed on a first and a second main surfaces; a cut-out part having a rectangular shape in plan view that is formed along an outer periphery of the vibrating part; an external frame part having a rectangular shape in plan view that is formed along an outer periphery of the cut-out part; and a connecting part that connects the vibrating part to the external frame part and that extends, in a Z′ axis direction of the vibrating part, from one end part of a side of the vibrating part along an X axis direction. The connecting part includes wide parts whose widths gradually increase only toward the external frame part.

A piezoelectric vibration element that includes a piezoelectric piece having a first principal surface and a second principal surface; a via electrode penetrating the piezoelectric piece from the first principal surface to the second principal surface thereof; a conductive etch stop film covering the via electrode on the second principal surface; and a wiring electrode covering at least part of an outer edge of the conductive etch stop film on the second principal surface.

A bulk acoustic wave (BAW) resonator includes a solidly mounted reflector, for example, a Bragg-type reflector, a piezoelectric layer, and first and second electrodes on first and second surfaces, respectively, of the piezoelectric layer. A filter device or filter system includes at least one BAW resonator. Related methods of fabrication include forming the BAW resonator.

A manufacturing method for an electronic component that includes a providing a base member on a first main surface of a first board, sandwiching the base member and a joining member paste between the first main surface of the first board and a transfer main surface of a transfer board, forming a joining member joined with the base member while the joining member paste is sandwiched by the first board and the transfer board, and peeling off the transfer board from the joining member joined with the base member.

A quartz crystal resonator unit that includes: a piezoelectric blank; a first excitation electrode on a first principal surface and within at least a part of a vibration portion of the piezoelectric blank; a second excitation electrode on a second principal surface and within at least a part of the vibration portion of the piezoelectric blank; a first extended electrode on the first principal surface and electrically connected to the first excitation electrode; and a second extended electrode on the second principal surface and electrically connected to the second excitation electrode; and an insulation layer including a hollow portion which defines a space with the second excitation electrode. A thickness of the first extended electrode is larger than a thickness of the second extended electrode. An end portion of the first extended electrode extends over the hollow portion in a plan view of the piezoelectric vibrator.

Acoustic wave filter devices are disclosed. In an embodiment, the device includes an acoustic wave resonator and a reflecting layer located below the acoustic wave resonator. The wave resonator includes an input electrode including a first electrode and a counter electrode, a piezoelectric layer sandwiched between the first electrode and the counter electrode, and an output electrode. The piezoelectric layer has a first region covered by the first or the output electrode, and a second region not covered by any of the first and the output electrode. The first region has a second order acoustic thickness-shear resonance (TS2) mode dispersion curve with a first minimum frequency, and the second region has a TS2 mode dispersion curve with a second minimum frequency. The reflecting layer's thickness is such that a difference between the first minimum frequency and the second minimum frequency is less than 2% of a filter center frequency.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. Patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the electrodes and a planarized support layer is deposited over the sacrificial layer. The device can include a dielectric protection layer (DPL) that protects the piezoelectric layer from etching processes that can produce rough surfaces and reduces parasitic capacitance around the perimeter of the resonator when the DPL’s dielectric constant is lower than that of the piezoelectric layer. The DPL can be configured between the top electrode and the piezoelectric layer, between the bottom electrode and the piezoelectric layer, or both.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

A bulk acoustic wave (BAW) resonator includes a solidly mounted reflector, for example, a Bragg-type reflector, a piezoelectric layer, and first and second electrodes on first and second surfaces, respectively, of the piezoelectric layer. A filter device or filter system includes at least one BAW resonator. Related methods of fabrication include forming the BAW resonator.