An acoustic wave device includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode facing each other across the piezoelectric film, at least one of the lower electrode and the upper electrode including a first conductive film and a second conductive film formed on the first conductive film; an insulating film sandwiched between the first conductive film and the second conductive film and having a temperature coefficient of an elastic constant opposite in sign to a temperature coefficient of an elastic constant of the piezoelectric film; and a third conductive film formed on edge surfaces of the insulating film and the second conductive film and causing electrical short circuits between the first conductive film and the second conductive film.

A lower electrode and an adhesive layer made of an insulator are formed on a back surface on the ion implantation layer side of a piezoelectric single crystal substrate. A supporting substrate in which sacrificial layers made of a conductive material have been formed is bonded to the surface of the adhesive layer. By heating the composite body including the piezoelectric single crystal substrate, the lower electrode, the adhesive layer, and the supporting substrate, a layer of the piezoelectric single crystal substrate is detached to form a piezoelectric thin film. A liquid polarizing upper electrode is formed on a detaching interface of the piezoelectric thin film. A pulsed electric field is applied using the polarizing upper electrode and the sacrificial layers as counter electrodes. Consequently, the piezoelectric thin film is polarized.

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 of manufacturing an integrated circuit. This method includes forming an epitaxial material comprising single crystal piezo material overlying a surface region of a substrate to a desired thickness and forming a trench region to form an exposed portion of the surface region through a pattern provided in the epitaxial material. Also, the method includes forming a topside landing pad metal and a first electrode member overlying a portion of the epitaxial material and a second electrode member overlying the topside landing pad metal. Furthermore, the method can include processing the backside of the substrate to form a backside trench region exposing a backside of the epitaxial material and the landing pad metal and forming a backside resonator metal material overlying the backside of the epitaxial material to couple to the second electrode member overlying the topside landing pad metal.

Provided in the present invention are a cavity-type bulk acoustic resonator without the need to prepare a sacrificial layer, and a preparation method therefor, comprising the following steps: taking a piezoelectric single crystal wafer subjected to ion implantation and having a bottom electrode, and forming a cavity on the side of the piezoelectric single crystal wafer having the bottom electrode; then taking a substrate, and bonding the substrate to the side of the piezoelectric single crystal wafer having the cavity; performing heat treatment on the bonded intermediate product to peel off the thin film of the piezoelectric single crystal wafer; and producing a top electrode on the peeled side of the piezoelectric single crystal wafer. The preparation method for the cavity-type bulk acoustic resonator without the need to prepare a sacrificial layer set forth in the present invention does not require the growth of a sacrificial layer, and does not perform etching and hole-forming on the thin film; the mechanical strength of the device is increased, and the thin film is not easily damaged; the cavity structure is formed before film forming, yield is high, and residue from etching is not left after film forming, there being no need to consider the effect of incomplete release on the device.

Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector electrode may include a first pair of top metal electrode layers electrically and acoustically coupled with the first and second layer of piezoelectric material to excite the piezoelectrically excitable resonance mode at a resonant frequency of the BAW resonator. The resonant frequency of the BAW resonator may be in a super high frequency band or an extremely high frequency band.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector including a first pair of top metal electrode layers may be electrically and acoustically coupled with the first layer of piezoelectric material to excite the piezoelectrically excitable main resonance mode at a resonant frequency.

A bulk acoustic wave resonator and manufacturing method thereof and filter, the bulk acoustic wave resonator includes: a resonant body structure, and a carrier structure and a cover structure on two opposite sides of the resonant body structure; a first cavity is between the carrier structure and the resonant body structure; the cover structure includes a cover substrate, and a cover bonding layer, a second cavity is between the cover structure and the resonant body structure; first and second conductive connectors, and a pad layer are on opposite sides of the resonant body structure, and the pad layer includes one or more bonding pads bonded with the cover bonding layer, each bonding pad has a recess recessed toward the resonant body structure, and the cover bonding layer includes a protrusion part filling the recess and surrounded by the bonding pad.

An acoustic resonator has a piezoelectric plate attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. An interdigital transducer (IDT) formed on the plate has interleaved fingers on the diaphragm with first parallel fingers extending from a first busbar and second parallel fingers extending from a second busbar of the IDT. A distance between the interleaved fingers defines an IDT pitch. The IDT has a gap distance between the ends of the first plurality of parallel fingers and the second busbar, and between the ends of the second plurality of parallel fingers and the first busbar; and the gap distance is less than times the IDT pitch.

The present application discloses a bulk acoustic wave resonator and a preparation method thereof. The bulk acoustic wave resonator includes: a substrate, a transducer stacking structure, and a protective layer; the transducer stacking structure is located on one side of the substrate; a cavity is arranged in the substrate; the cavity penetrates through a portion of the substrate; a release channel is arranged in the transducer stacking structure; the release channel penetrates through the transducer stacking structure and is communicated to the cavity; the protective layer is arranged on a surface of one side of the transducer stacking structure away from the substrate; and the protective layer includes a waterproof material.