An RF triplexer 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.

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.

Techniques are disclosed for forming integrated circuit single-flipped resonator devices that include an electrode formed of a two-dimensional electron gas (2 DEG). The disclosed resonator devices may be implemented with various group III-nitride (III-N) materials, and in some cases, the 2 DEG may be formed at a heterojunction of two epitaxial layers each formed of III-N materials, such as a gallium nitride (GaN) layer and an aluminum nitride (AlN) layer. The 2 DEG electrode may be able to achieve similar or increased carrier transport as compared to a resonator device having an electrode formed of metal. Additionally, in some embodiments where AlN is used as the piezoelectric material for the resonator device, the AlN may be epitaxially grown which may provide increased performance as compared to piezoelectric material that is deposited by traditional sputtering techniques.

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.

Techniques are disclosed for forming integrated circuit film bulk acoustic resonator (FBAR) devices having multiple resonator thicknesses on a common substrate. A piezoelectric stack is formed in an STI trench and overgrown onto the STI material. In some cases, the piezoelectric stack can include epitaxially grown AlN. In some cases, the piezoelectric stack can include single crystal (epitaxial) AlN in combination with polycrystalline (e.g., sputtered) AlN. The piezoelectric stack thus forms a central portion having a first resonator thickness and end wings extending from the central portion and having a different resonator thickness. Each wing may also have different thicknesses from one another. Thus, multiple resonator thicknesses can be achieved on a common substrate, and hence, multiple resonant frequencies on that same substrate. The end wings can have metal electrodes formed thereon, and the central portion can have a plurality of IDT electrodes patterned thereon.

An elastic wave device includes a supporting substrate, an acoustic reflection layer disposed on the supporting substrate, a piezoelectric layer disposed on the acoustic reflection layer, and an interdigital transducer electrode disposed on the piezoelectric layer. The acoustic reflection layer includes three or more low acoustic impedance layers and two or more high acoustic impedance layers. A film thickness of the low acoustic impedance layer closest to the piezoelectric layer is larger than a film thickness of the low acoustic impedance layer closest to the low acoustic impedance layer that is closest to the piezoelectric layer.

A method for making a bandpass filter including a first and second bulk acoustic wave resonators, the resonant frequency of the second resonator being offset from that of the first resonator by a predetermined offset, the method including providing a piezoelectric on insulator substrate, forming a lower electrode of the first resonator and a lower electrode of the second resonator, assembling by bonding the donor substrate to a receiver substrate, removing the donor substrate with a barrier on the piezoelectric layer, forming an upper electrode of the first resonator and an upper electrode, forming the lower electrodes being preceded by forming a mass overload pattern at the second zone, and/or forming the upper electrodes being preceded by forming a mass overload pattern at the second zone, the total thickness of the mass overload pattern or patterns being chosen to offset the resonant frequency of the second resonator by the offset.

A method of forming a MEMS/integrated circuit structure can include forming a piezoelectric layer on a surface of a growth substrate, forming a first electrode on the piezoelectric layer, forming a support layer on the piezoelectric layer and the first electrode, bonding an upper surface of the support layer to an upper surface of an integrated circuit wafer to form a bonded interface therebetween, wherein the integrated circuit wafer includes a substrate, a plurality of first layers on the substrate, the plurality of first layers forming a front-end of line portion of the integrated circuit wafer having electronic semiconductor switching devices therein, and a plurality of second layers forming a back-end of line portion of the integrated circuit wafer including ohmic conductors ohmically coupling regions of the electronic semiconductor switching devices to an outer one of the second layers of the integrated circuit wafer positioned opposite the electronic semiconductor switching devices.

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.

Acoustic resonators and filter devices, and method of making acoustic resonators and filter devices. An acoustic resonator includes a substrate having a surface and a piezoelectric plate having front and back surfaces, the back surface attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The interleaved fingers have an irregular hexagon cross-sectional shape.