An acoustic wave device, includes piezoelectric layer having an upper piezoelectric surface and a lower piezoelectric surface; an upper electrode formed on the upper piezoelectric surface; a lower electrode; a support layer including a non-monocrystalline insulating material; and a lower cover, wherein the lower electrode and the support layer formed between the lower cover and the lower piezoelectric surface.

The present disclosure provides a bulk acoustic wave (BAW) filter structure and a preparation method thereof. According to the present disclosure, piezoelectric film elements are formed on a surface of an epitaxial substrate to form a transfer structure; resonant regions are defined on a supporting substrate and covered with bonding units to obtain a bonding structure; upper and lower surfaces of the transfer structure are reversed, and bottom electrode units are bonded to the resonant regions correspondingly one to one to obtain a BAW structure; and the epitaxial substrate is removed, and top electrode units are formed on surfaces of the piezoelectric film elements that are in contact with the epitaxial substrate previously. The BAW filter structure of the present disclosure can achieve batch production with low cost, high efficiency and high yield.

Techniques to fabricate an RF filter using 3 dimensional island integration are described. A donor wafer assembly may have a substrate with a first and second side. A first side of a resonator layer, which may include a plurality of resonator circuits, may be coupled to the first side of the substrate. A weak adhesive layer may be coupled to the second side of the resonator layer, followed by a low-temperature oxide layer and a carrier wafer. A cavity in the first side of the resonator layer may expose an electrode of the first resonator circuit. An RF assembly may have an RF wafer having a first and a second side, where the first side may have an oxide mesa coupled to an oxide layer. A first resonator circuit may be then coupled to the oxide mesa of the first side of the RF wafer.

A filter package comprising an array of piezoelectric films sandwiched between lower electrodes and an array of upper electrodes covered by an array of silicon membranes with cavities thereover: the lower electrode being coupled to an interposer with a first cavity between the lower electrodes and the interposer; the array of silicon membranes having a known thickness and attached over the upper electrodes with an array of upper cavities, each upper cavity between a silicon membrane of the array and a common silicon cover; each upper cavity aligned with a piezoelectric film, an upper electrode and silicon membrane, the upper cavities having side walls comprising SiO.sub.2; the individual piezoelectric films, their upper electrodes and silicon membranes thereover being separated from adjacent piezoelectric films, upper electrodes and silicon membranes by a passivation material.

An acoustic resonator includes a membrane layer disposed on an insulating layer; a cavity formed by the insulating layer and the membrane layer and having a hydrophobic layer disposed on at least one of a portion of an upper surface of the cavity and a portion of a lower surface of the cavity; and a resonating portion disposed on the cavity and having a second electrode on a piezoelectric layer on a first electrode.

An acoustic resonator includes a membrane layer disposed on an insulating layer; a cavity formed by the insulating layer and the membrane layer; a resonating portion disposed on the cavity and having a first electrode, a piezoelectric layer, and a second electrode stacked thereon; a protective layer disposed on the resonating portion; and a hydrophobic layer formed on the protective layer.

A method of manufacture and structure for an acoustic resonator device having a hybrid piezoelectric stack with a strained single crystal layer and a thermally-treated polycrystalline layer. The method can include forming a strained single crystal piezoelectric layer overlying the nucleation layer and having a strain condition and piezoelectric layer parameters, wherein the strain condition is modulated by nucleation growth parameters and piezoelectric layer parameters to improve one or more piezoelectric properties of the strained single crystal piezoelectric layer. Further, the method can include forming a polycrystalline piezoelectric layer overlying the strained single crystal piezoelectric layer, and performing a thermal treatment on the polycrystalline piezoelectric layer to form a recrystallized polycrystalline piezoelectric layer. The resulting device with this hybrid piezoelectric stack exhibits improved electromechanical coupling and wide bandwidth performance.

A filter package comprising an array of piezoelectric films sandwiched between an array of upper electrodes and lower electrodes: the individual piezoelectric films and the upper electrodes being separated by a passivation material; the lower electrode being coupled to an interposer with a first cavity between the lower electrodes and the interposer; the filter package further comprising a silicon wafer of known thickness attached over the upper electrodes with an array of upper cavities between the silicon wafer and a silicon cover; each upper cavity aligned with a piezoelectric film in the array of piezoelectric films, the upper cavities having side walls comprising the passivation material.

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.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.