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.

Disclosed is a method for manufacturing a piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin film, comprising: forming a stress control layer comprised of a Group III nitride on a silicon substrate by chemical vapor deposition (CVD); and depositing a piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin film on the stress control layer, the thin film being deposited by PVD at 0.3 Tm (Tm is melting temperature of a piezoelectric thin film material) or higher. Further, a method for manufacturing a device in conjunction with piezoelectric Al.sub.xGa.sub.1-xN (0.5≤x≤1) thin films is provided.

An acoustic resonator device with low thermal impedance has a substrate and a single-crystal piezoelectric plate having a back surface attached to a top surface of the substrate via a bonding oxide (BOX) layer. An interdigital transducer (IDT) formed on the front surface of the plate has interleaved fingers disposed on the diaphragm. The piezoelectric plate and the BOX layer are removed from a least a portion of the surface area of the device to provide lower thermal resistance between the IDT and the substrate.

A method of forming a film bulk acoustic wave resonator comprises depositing a bottom electrode on an upper surface of a layer of dielectric material disposed over a cavity defined between the layer of dielectric material and a substrate, depositing a seed layer of piezoelectric material on an upper surface of the bottom electrode, etching one or more openings through the seed layer of piezoelectric material, etching of the one or more openings including over-etching of the seed layer in an amount sufficient to damage portions of the upper surface of the bottom electrode exposed by etching of the one or more openings, and depositing a bulk film of the piezoelectric material on an upper surface of the seed layer, on a portion of the upper surface of bottom electrode including the damaged portions, and on a portion of the upper surface of the dielectric layer.

A deposition system is disclosed that allows for growth of inclined c-axis piezoelectric material structures. The system integrates various sputtering modules to yield high quality films and is designed to optimize throughput lending it to a high-volume in manufacturing environment. The system includes two or more process modules including an off-axis module constructed to deposit material at an inclined c-axis and a longitudinal module constructed to deposit material at normal incidence; a central wafer transfer unit including a load lock, a vacuum chamber, and a robot disposed within the vacuum chamber and constructed to transfer a wafer substrate between the central wafer transfer unit and the two or more process modules; and a control unit operatively connected to the robot.

A piezoelectric thin film includes a piezoelectric element and a substrate supporting the piezoelectric element. The piezoelectric element includes a piezoelectric thin film and first and second electrodes opposing each other with the piezoelectric thin film interposed therebetween. The piezoelectric thin film has a first-electrode-side content of each of aluminum and scandium higher than a second-electrode-side content thereof and a first-electrode-side content of nitrogen lower than a second-electrode-side content thereof.

A film bulk acoustic resonator (FBAR) structure includes a top electrode, a piezoelectric layer disposed below the top electrode, a bottom electrode disposed below the piezoelectric layer, a dielectric layer disposed below the bottom electrode, a bonding substrate disposed below the dielectric layer, a bottom cap wafer disposed below the bonding substrate, and a cavity disposed below the bottom electrode and formed by the dielectric layer, the bonding substrate, and the bottom cap wafer.

Techniques are disclosed for forming high frequency film bulk acoustic resonator (FBAR) devices using epitaxially grown piezoelectric films. In some cases, the piezoelectric layer of the FBAR may be an epitaxial III-V layer such as an aluminum nitride (AlN) or other group III material-nitride (III-N) compound film grown as a part of a III-V material stack, although any other suitable piezoelectric materials can be used. Use of an epitaxial piezoelectric layer in an FBAR device provides numerous benefits, such as being able to achieve films that are thinner and higher quality compared to sputtered films, for example. The higher quality piezoelectric film results in higher piezoelectric coupling coefficients, which leads to higher Q-factor of RF filters including such FBAR devices. Therefore, the FBAR devices can be included in RF filters to enable filtering high frequencies of greater than 3 GHz, which can be used for 5G wireless standards, for example.

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.

Bulk acoustic wave resonators of two or more different filters can be on a common die. The two filters can be included in a multiplexer, such as a duplexer, or implemented as standalone filters. With bulk acoustic wave resonators of two or more filters on the same die, the filters can be implemented in less physical space compared to implementing the same filters of different die. Related methods, radio frequency systems, radio frequency modules, and wireless communication devices are also disclosed.