An elastic wave device in which an IDT electrode defines an excitation electrode on a piezoelectric layer, an acoustic reflection layer is laminated on a first main surface of the piezoelectric layer, the acoustic reflection layer includes high acoustic impedance layers with a relatively high acoustic impedance and low acoustic impedance layers with a relatively low acoustic impedance, and the acoustic reflection layer has an unwanted wave reflection suppression structure in which reflection of unwanted waves toward the piezoelectric layer side is significantly reduced or prevented.

The present disclosure relates to a tunable Bulk Acoustic Wave (BAW) resonator with a top electrode, a bottom electrode, a piezoelectric layer sandwiched between the top electrode and the bottom electrode, and a reflection region underneath the bottom electrode. The reflection region includes a reflection layer and an ion-conductible structure between the bottom electrode and the reflection layer. Herein, the ion-conductible structure has a first terminal layer coupled to the bottom electrode, a second terminal layer coupled to the reflection layer, and an ion conductor between the first terminal layer and the second terminal layer. The ion conductor is eligible to transport ions between the first terminal layer and the second terminal layer, so as to achieve a mass-loading shift between the first terminal layer and the second terminal layer, and consequently, to tune a resonance frequency of the tunable BAW resonator.

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 5.5 GHz Wi-Fi acoustic wave resonator RF filter circuit. The device can include a power amplifier (PA), a 5.5 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 5.5 GHZ resonator may be configured between the diversity switch and the LNA. In a specific example, this device integrates a 5.5 GHz PA, a 5.5 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.

Embodiments provide a solidly-mounted bulk acoustic wave (BAW) resonator and method of making same. In embodiments, the BAW resonator may include a planarization portion in an inactive region of the BAW resonator that is coplanar with a piezoelectric layer of the BAW resonator in an active region of the BAW resonator. Other embodiments may be described and claimed.

A BAW resonator comprises a bottom electrode, a piezoelectric layer and a top electrode. A top electrode connection is arranged in a plane above the top electrode. For doing this a spacer is arranged on the top electrode. A capping layer is sitting on the spacer distant from the top electrode such that an air-filled gap to the top electrode is kept. The top electrode connection can now be arranged above the capping layer. An electrically conductive path connects the top electrode and the top electrode connection. Such a resonator needs only one lateral design and can provide a low-ohmic interconnection of resonators e.g. in a filter circuit.

A seed layer (210) of a noble metal is formed by electrochemical deposition on a metal electrode (111) disposed on a dielectric layer (110,310). The noble metal seed layer allows the deposition of a highly textured piezoelectric layer (320) on the metal electrode.

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 digitally tunable acoustic wave resonator includes, in part, a first electrode positioned above a substrate, a composite stack positioned above the first electrode, and a second electrode positioned above the composite stack. The composite stack may include one or more alternate layers of a ferroelectric layer and a transition-metal nitride layer. The transition-metal nitride layer can be positioned above the ferroelectric layer, except the ferroelectric layer at the top of the composite stack. The ferroelectric layer comprises an aluminum scandium nitride layer Al.sub.1-xSc.sub.xN, where 0<x<1.