An acoustic resonator is fabricated with a substrate having a substrate top surface and a piezoelectric plate having plate front and plate back surfaces. An acoustic Bragg reflector is sandwiched between the substrate top surface and the plate back surface. The reflector has a cavity with a top surface perimeter, and the acoustic Bragg reflector is configured to reflect shear acoustic waves at a resonance frequency of the acoustic resonator. The back surface is mounted on the cavity top surface perimeter except for a portion of the plate forming a diaphragm that spans the cavity. An interdigital transducer (IDT) is formed on the plate front surface such that interleaved fingers of the IDT are disposed on the diaphragm. Two or more layers of the acoustic Bragg reflector form pedestals that support the back surface of the plate opposite some or all interleaved fingers of the IDT.

A bulk acoustic wave resonator includes a substrate, a support layer disposed on the substrate, the support layer including a cavity having a polygon shape with more than three sides in a plane crossing a first direction from the substrate to the support layer, a piezoelectric layer disposed on the support layer, a bottom electrode disposed below the piezoelectric layer, partially overlapping the cavity, and extending across a first side of the cavity, and a top electrode disposed above the piezoelectric layer, partially overlapping the cavity, and extending across a second side of the cavity. The bulk acoustic wave resonator further includes at least one release hole formed in the piezoelectric layer and overlapping a portion of the cavity.

A 6 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 310 nm, and each of the two or more series XBARS includes a diaphragm having an LN-equivalent thickness less than or equal to 305 nm.

A BAW resonator includes: a piezoelectric film array, including multiple piezoelectric films between a substrate of a chip and a capping layer on the top, where multiple first cavities are provided between adjacent piezoelectric films in a vertical direction, between the piezoelectric films and the capping layer, and between the piezoelectric films and the substrate, second cavities are shared between adjacent piezoelectric films in a first direction in a horizontal plane, and third cavities are shared between adjacent piezoelectric films in a second direction in the horizontal plane; multiple electrode layers, covering at least the top surface and bottom surface of each of the piezoelectric films; and multiple electrode interconnection layers, connected to the electrode layers on the bottom surfaces of the piezoelectric films along sidewalls of the third cavities.

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.170 GHz to 5.835 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

A thin film bulk acoustic resonator and a method for manufacturing the same. The thin film bulk acoustic resonator comprises a bottom electrode layer, a piezoelectric layer, and a top electrode layer, which are disposed on a substrate in which an acoustic reflection structure is located, where a portion which is of the piezoelectric layer and corresponds to a boundary of the acoustic reflection structure is depolarized to form a depolarized portion. The method comprises providing a bottom electrode layer on a substrate to cover an acoustic reflection structure which is formed or to be formed on the substrate; providing a piezoelectric layer on the bottom electrode layer; depolarizing a portion, which is of the piezoelectric layer and corresponds to a boundary of the acoustic reflection structure, to form a depolarized portion; and providing a top electrode layer on the piezoelectric layer.

An acoustic wave device fabrication method includes: forming on a piezoelectric substrate a comb-shaped electrode and a wiring layer coupled to the comb-shaped electrode; forming on the piezoelectric substrate a first dielectric film having a film thickness greater than those of the comb-shaped electrode and the wiring layer, covering the comb-shaped electrode and the wiring layer, and being made of silicon oxide doped with an element or undoped silicon oxide; forming on the first dielectric film a second dielectric film having an aperture above the wiring layer; removing the first dielectric film exposed by the aperture of the second dielectric film by wet etching using an etching liquid causing an etching rate of the second dielectric film to be less than that of the first dielectric film so that the first dielectric film is left so as to cover an end face of the wiring layer and the comb-shaped electrode.

Switchable and/or tunable filters, methods of manufacture and design structures are disclosed herein. The method of forming the filters includes forming at least one piezoelectric filter structure comprising a plurality of electrodes formed to be in contact with at least one piezoelectric substrate. The method further includes forming a micro-electro-mechanical structure (MEMS) comprising a MEMS beam in which, upon actuation, the MEMS beam will turn on the at least one piezoelectric filter structure by interleaving electrodes in contact with the piezoelectric substrate or sandwiching the at least one piezoelectric substrate between the electrodes.

Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0°], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.

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.