The invention discloses a bulk acoustic wave resonator and a manufacturing method thereof, the bulk acoustic wave resonator comprising: an air gap arranged at the external of the effective piezoelectric region, the air gap being formed between the upper electrode and the piezoelectric layer and/or between the piezoelectric layer and the substrate, and covering the end part, proximal to the air gap, of the lower electrode or connecting to the end part of the lower electrode, wherein the air gap is provided with a first end proximal to the effective piezoelectric region, and at least a portion of the upper surface, starting from the first end, of the air gap is an arch-shaped upper surface. The bulk acoustic wave resonator of the present invention capable of increasing a quality factor (Q) and an effective electromechanical coupling coefficient (K.sup.2.sub.t,eff) and improving the electrostatic discharge (ESD) immunity.

An acoustic wave device includes a supporting substrate, an acoustic reflection film the supporting substrate, a piezoelectric thin film on the acoustic reflection film, and an interdigital transducer electrode the piezoelectric thin film. The acoustic reflection film includes acoustic impedance layers including therein first, second, third, and fourth low acoustic impedance layers and first, second, and third high acoustic impedance layers. The acoustic reflection film includes a first acoustic impedance layer and a second acoustic impedance layer, the first and second acoustic impedance layers each being one of the acoustic impedance layers, and the second acoustic impedance layer has an arithmetic average roughness different from that of the first acoustic impedance layer.

A bulk-acoustic wave resonator includes a substrate, a cavity formed in the substrate, a first electrode, a piezoelectric layer, and a second electrode stacked in order on the substrate, a resonator defined by the first electrode, the piezoelectric layer, and the second electrode overlapping in a vertical direction in an upper portion of the cavity, an additional layer disposed on one surface of the first electrode arranged in a wiring region on an external side of the resonator, and a wiring electrode connected to the first electrode arranged in the wiring region. The first electrode forms a contact interfacial surface with the additional layer and the wiring electrode.

An RF integrated circuit device can includes a substrate and a High Electron Mobility Transistor (HEMT) device on the substrate including a ScAlN layer configured to provide a buffer layer of the HEMT device to confine formation of a 2DEG channel region of the HEMT device. An RF piezoelectric resonator device can be on the substrate including the ScAlN layer sandwiched between a top electrode and a bottom electrode of the RF piezoelectric resonator device to provide a piezoelectric resonator for the RF piezoelectric resonator device.

A method for creating a double Bragg mirror is provided. The method comprises providing a wafer having a plurality of bulk acoustic wave (BAW) devices at an intermediate stage of manufacturing. A first dielectric layer is deposited over the wafer. A plurality of as-deposited thicknesses of the dielectric layer are determined, each as-deposited thickness corresponding to one BAW device from the plurality of BAW devices. A corresponding trimmed dielectric layer over each of the BAW devices is formed by removing a portion of the dielectric layer over each of the BAW devices, with a thickness of the removed portion determined from a corresponding as-deposited thickness and a target thickness. A Bragg acoustic reflector that includes the corresponding trimmed dielectric layer is formed over each of the BAW devices.

A front end module (FEM) for a 5.6 GHz Wi-Fi acoustic wave resonator RF filter circuit. The device can include a power amplifier (PA), a 5.6 GHz resonator, and a diversity switch. The device can further include a low noise amplifier (LNA). The PA is electrically coupled to an input node and can be configured to a DC power detector or an RF power detector. The resonator can be configured between the PA and the diversity switch, or between the diversity switch and an antenna. The LNA may be configured to the diversity switch or be electrically isolated from the switch. Another 5.6 GHZ resonator may be configured between the diversity switch and the LNA. In a specific example, this device integrates a 5.6 GHz PA, a 5.6 GHZ bulk acoustic wave (BAW) RF filter, a single pole two throw (SP2T) switch, and a bypassable LNA into a single device.

A piezoelectric device includes a foundation structure and a plurality of metal islands distributed over a first area of a top surface of the foundation structure. A piezoelectric film resides over the foundation structure and is formed from a piezoelectric material. The piezoelectric film has a non-piezoelectric portion over the first area and a piezoelectric portion over a second area of the top surface of the foundation structure. Within the non-piezoelectric portion, the piezoelectric film is polarity patterned to have pillars and a mesh. The pillars of the piezoelectric material have a first polar orientation residing over corresponding ones of the plurality of metal islands. The mesh of the piezoelectric material has a second polar orientation, which is opposite that of the first polar orientation, and surrounds the pillars. In one embodiment, the metal islands are self-assembled islands.

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 method for forming an aluminum nitride layer (310, 320) comprises the provision of a substrate (100) and the forming of a patterned metal nitride layer (110). A bottom electrode metal layer (210) is formed on the exposed portions (101) of the substrate. An aluminum nitride layer portion (320) grown above the exposed portion (101) of the substrate (100) exhibits piezoelectric properties. An aluminum nitride layer portion (310) grown above the patterned metal nitride layer (110) exhibits no piezoelectric properties (310). Both aluminum nitride layer portions (320, 310) are grown simultaneously.

An aluminum nitride film contains a Group IV element and a Group II or Group XII element, and an atomic composition ratio of the Group II or Group XII element to the Group IV element is less than 1.