A MEMS (microelectromechanical system) resonator includes a first layer of single-crystalline silicon, a second layer of single-crystalline silicon, and a piezoelectric layer in between said first layer of single-crystalline silicon and the second layer of single-crystalline silicon. A manufacturing method of the MEMS resonator includes at least one of the interfaces between the single-crystalline silicon layers and the piezoelectric layer be made by wafer bonding.

A resonator and a preparation method of a resonator, and a filter relate to the technical field of resonators. The preparation method includes: forming a piezoelectric layer, a first electrode layer, and a first bonding layer on a first substrate; patterning the first bonding layer to form a first bonding ring, a second bonding ring, and a third bonding ring, and etching an exposed part of the first electrode layer to form a first window; forming a first supporting layer and a second bonding layer on the second substrate; patterning the second bonding layer to form a fourth bonding ring and a fifth bonding ring, and etching an exposed part of the first supporting layer to form a second window and a third window to obtain a boundary ring located between the third window and the second window; bonding the third bonding ring and the fifth bonding ring, and bonding the second bonding ring and the fourth bonding ring to obtain a cavity structure of the resonator; and removing the first substrate, and forming a second electrode layer on the piezoelectric layer. According to the preparation method, preparation of the boundary ring is realized through a packaging and bonding process, and the preparation process of a resonator is simple.

A resonator includes a piezoelectric layer comprising a piezoelectric material, the piezoelectric layer having a first surface and a second surface; an inner electrode disposed on the first surface of the piezoelectric layer, the inner electrode connected to a circuit; and an outer electrode surrounding the inner electrode on the first surface of the piezoelectric layer, the outer electrode left floating or connected to ground. The inner electrode and the outer electrode are separated by at least one gap smaller than an acoustic wavelength. One single piece electrode or multiple piece electrodes may be disposed on the second surface of the piezoelectric layer. The outer electrodes are configured for optimal modal confinement of an acoustic resonance while the inner electrodes are configured to produce a higher motional resistance than the interconnect resistance for maintaining high Q.

A RF antenna or sensor has a substrate, a resonator operable at UHF disposed on the substrate, the resonator preferably having a quartz bar or body with electrodes disposed on opposing major surfaces thereof and with a magnetostrictive material disposed on or covering at least one of the electrodes. A pair of trapezoidal, triangular or wing shaped high permeability pole pieces preferably supported by that substrate are disposed confronting the resonator, one of the pair being disposed one side of the resonator and the other one of the pair being disposed on an opposing side of said resonator, the pair of high permeability pole pieces being spaced apart by a gap G, the resonator being disposed within that gap G. The size of gap G is preferably less than 100 μm.

A process for fabricating a micro-electro-mechanical system, includes the following steps: production of a stack on the surface of a temporary substrate so as to produce a first assembly, comprising: at least depositing a piezoelectric material or a ferroelectric material to produce a layer of piezoelectric material or of ferroelectric material; producing a first bonding layer; production of a second assembly comprising at least producing a second bonding layer on the surface of a host substrate; production of at least one acoustic isolation structure in at least one of the two assemblies; production of at least one electrode level containing one or more electrodes in at least one of the two assemblies; bonding the two assemblies via the two bonding layers, before or after the production of the at least one electrode level in at least one of the two assemblies; removing the temporary substrate.

Acoustic resonator devices and methods are disclosed. An acoustic resonator device includes a substrate having a front surface and a cavity, a perimeter of the cavity defined by a lateral etch-stop comprising etch-stop material. A back surface of a single-crystal piezoelectric plate is attached to the front surface of the substrate except for a portion of the piezoelectric plate that forms a diaphragm that spans the cavity. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The piezoelectric plate and the IDT are configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm.

Techniques for improving structures, acoustic wave resonators, layers, and devices are disclosed, including filters, oscillators and systems that may include such devices. An acoustic wave device of this disclosure may comprise a substrate and a piezoelectric resonant volume. The piezoelectric resonant volume of the acoustic wave device may have a main resonant frequency. The acoustic wave device may comprise a first distributed Bragg acoustic reflector. The first distributed Bragg acoustic reflector may comprise a first active piezoelectric layer. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in a super high frequency (SHF) band. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in an extremely high frequency (EHF) band.

A bulk acoustic resonator includes: a substrate; a first electrode disposed on the substrate; a piezoelectric layer disposed to cover at least a portion of the first electrode; a second electrode disposed to cover at least a portion of the piezoelectric layer; a metal pad connected to the first electrode and the second electrode; and a protective layer disposed to cover at least the metal pad.

A BAW resonance device, a filter device and an RF front-end device are provided. The BAW resonance device comprises a first passive part including a first substrate and a first heat-dissipation layer located over the first substrate; a first active part including a first piezoelectric layer, a first electrode layer and a second electrode layer, wherein the first piezoelectric layer is located over the first passive part and has a first side and a second side opposite to the first side, the first passive part is located on the first side, the first electrode layer is also located on the first side and is disposed between the first passive part and the first piezoelectric layer, and the second electrode layer is located on the second side; and a first cavity located on the first side and disposed between the first passive part and the first piezoelectric layer, wherein at least one part of the first electrode layer is located on or in the first cavity. The first heat-dissipation layer can improve or flexibly adjust the heat-dissipation performance of the SAW resonance device.

An acoustic wave device includes a support substrate, a piezoelectric layer overlapping the support substrate viewed in a first direction, a functional electrode on at least a first main surface of the piezoelectric layer, and a wiring electrode connected to the functional electrode. A space is provided on a second main surface side opposite to the first main surface of the piezoelectric layer. The space is covered with the piezoelectric layer, the wiring electrode covers a portion of the functional electrode, and an air gap or an insulating film is provided between the functional electrode and the wiring electrode in a region where the functional electrode is covered with the wiring electrode.