A bulk acoustic resonator comprises a membrane including a piezoelectric film having multiple layers of piezoelectric material. At least one of the multiple layers of piezoelectric material has a different dopant concentration than another of the multiple layers of piezoelectric material.

A crystal oscillator includes a piezoelectric substrate, a first electrode, a second electrode, and a support frame. The first electrode includes a first electrode portion disposed on a first surface of the piezoelectric substrate. The second electrode is disposed on a second surface of the piezoelectric substrate opposite to the first surface of the piezoelectric substrate. The support frame is made of a photoresist material, and is disposed on the second surface. The support frame surrounds the second electrode portion. At least a portion of the second extending electrode portion is located outside the support frame. A method for making the crystal oscillator is also provided herein.

A crystal oscillator includes an oscillating substrate, a hollow frame, a first electrode, and a second electrode. The oscillating substrate includes a main oscillating region and a thinned region that has a thickness smaller than that of the main oscillating region. The first and second electrodes are disposed on a first surface of the oscillating substrate and a second surface opposite to the first surface, respectively. The hollow frame is disposed on the second surface. The second electrode includes a second electrode portion that has at least one opening in positional correspondence with the thinned region. A method for making the crystal oscillator is also provided herein.

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 system for a wireless communication infrastructure using single crystal devices. The wireless system can include a controller coupled to a power source, a signal processing module, and a plurality of transceiver modules. Each of the transceiver modules includes a transmit module configured on a transmit path and a receive module configured on a receive path. The transmit modules each include at least a transmit filter having one or more filter devices, while the receive modules each include at least a receive filter. Each of these filter devices includes a single crystal acoustic resonator device formed with a thin film transfer process with at least a first electrode material, a single crystal material, and a second electrode material. Wireless infrastructures using the present single crystal technology perform better in high power density applications, enable higher out of band rejection (OOBR), and achieve higher linearity as well.

A bulk acoustic resonator having a heat dissipation structure, and a fabrication process are provided according to the present application. The bulk acoustic resonator includes a substrate, a metal heat dissipation layer formed on the base substrate and provided with an insulating layer on the surface thereof, and a resonance functional layer formed on the insulating layer, where the metal heat dissipation layer and the insulating layer together define a cavity on the substrate, a side wall of the cavity is formed by the insulating layer, and a bottom electrode layer in the resonance function layer covers the cavity.

A film bulk acoustic wave resonator comprising a piezoelectric film having a central region defining a main active domain in which a main acoustic wave is generated during operation, an upper electrode disposed on a top surface of the piezoelectric film, a lower electrode disposed on a lower surface of the piezoelectric film, a dielectric material layer disposed on a lower surface of the lower electrode, and lower recessed frame regions disposed laterally on opposite sides of the central region, the lower recessed frame regions defined by regions of one of the dielectric material or of the lower electrode having a lesser thickness than the thickness of the one of the dielectric material layer or of the lower electrode in the central region.

A 5 GHz Wi-Fi bandpass filter includes a ladder filter circuit with two or more shunt transversely-excited film bulk acoustic resonators (XBARs) and two or more series XBARs. Each of the two or more shunt XBARS includes a diaphragm having an LN-equivalent thickness greater than or equal to 360 nm, and each of the two or more series XBARS includes a diaphragm having an LN-equivalent thickness less than or equal to 375 nm.

The present invention provides a preparation method of solid reflection-type bulk acoustic resonator, including the following steps: taking a piece of ion-implanted piezoelectric material, growing reflecting layers below the implantation face of the piezoelectric material and/or above the substrate, then taking a substrate, and bonding it to the piezoelectric material; heating the bonded intermediate product gained to strip the film from the piezoelectric material and growing an upper electrode on the stripped side of the piezoelectric material. According to the preparation method of solid reflection-type bulk acoustic resonator disclosed in the present invention, resonators with high strength and good performance can be prepared by using wafer bonding and lay transfer technique for preparing high-quality piezoelectric films and combining the solid reflecting layer structure.

A film bulk acoustic wave resonator (FBAR) is disclosed with recessed and raised frame portions in the piezoelectric film. The FBAR can include a substrate, the piezoelectric film supported to oscillate in a direction opposite to a main surface of the substrate, and a pair of top and bottom electrodes formed respectively on top and bottom surfaces of the film. The recessed frame portion and the raised frame portion can be formed in the film to extend adjacent to each other along a periphery of an active region of the film oscillating during an operation of the film on a top surface of the top electrode.