Acoustic resonators and filters are disclosed. An acoustic resonator includes a substrate and a piezoelectric plate. A back surface of the piezoelectric plate is attached to the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern including an interdigital transducer (IDT) is formed on a front surface of the piezoelectric plate, interleaved fingers of the IDT disposed on the diaphragm. A front-side dielectric layer is formed on the front surface of the piezoelectric plate between, but not over, the IDT fingers. A back-side dielectric layer is formed on a back surface of the diaphragm. Thicknesses of the IDT fingers and the front-side dielectric layer are substantially equal. An acoustic impedance Zm of the IDT fingers and an acoustic impedance Zfd of the front-side dielectric layer satisfy the relationship 0.8Zm≤Zfd≤1.25Zm.

In bulk acoustic wave (BAW) resonators having convex surfaces, an example BAW resonator includes a first electrode, a piezoelectric layer formed on the first electrode, the piezoelectric layer having a convex surface, and a second electrode formed on the convex surface. An example integrated circuit (IC) package includes a BAW resonator in the IC package, the BAW resonator including a piezoelectric layer having a convex surface.

Provided is a bulk acoustic wave resonator. The bulk acoustic wave resonator includes a first electrode, a piezoelectric layer and a second electrode, where the piezoelectric layer is disposed between the first electrode and the second electrode, the piezoelectric layer is provided with at least one slit, and along a direction pointing from the first electrode to the second electrode, the at least one slit penetrates through at least the piezoelectric layer.

An acoustic wave element which can be reduced in size and produced relatively easily, practically used without using harmful substances, and can suppress a surface acoustic wave propagation loss, which has an excellent temperature coefficient of frequency and a velocity dispersion characteristic, and with which an increase in the reflection coefficient of interdigital transducers can be suppressed, and a method for manufacturing the acoustic wave element are provided. The acoustic wave element includes a pair of electrodes provided on both surfaces of a piezoelectric substrate, and a dielectric film provided on a first surface of the piezoelectric substrate so as to cover the electrode. The acoustic wave element alternatively includes interdigital transducers provided on a first surface of the piezoelectric substrate, and a dielectric film provided on the interdigital transducers, a gap between the interdigital transducers, and/or a second surface of the piezoelectric substrate.

The present disclosure provides a bulk acoustic wave resonator, a manufacturing method thereof, and a filter, wherein the bulk acoustic wave resonator includes: a substrate; an acoustic reflection unit on the substrate; a piezoelectric stack structure on the acoustic reflection unit; and a pad on the piezoelectric stack structure; wherein the pad has an overlapping region with the acoustic reflection unit. The acoustic wave resonator, the manufacturing method thereof and the filter of the present disclosure can effectively reduce connection resistance of the bulk acoustic wave resonator, thereby reducing insertion loss of the filter.

Acoustic resonator devices, filter devices, and methods of fabrication. A resonator device includes a piezoelectric plate having a front surface and a back surface opposite the front surface, a back-side conductor pattern formed on the back surface, and a first front-side conductor pattern and a second front-side conductor pattern formed on respective portions of the front surface opposite the back-side conductor pattern. A portion of the piezoelectric plate between the first front-side conductor pattern and the back-side conductor pattern forms a first resonator and a portion of the piezoelectric plate between the second front-side conductor pattern and the back-side conductor pattern forms a second resonator.

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.

Acoustic sensor devices and sensor systems are disclosed. An acoustic sensor device includes a piezoelectric plate having a front surface and a back surface. A floating back-side conductor pattern is formed on the back surface. A first and second front-side conductor patterns are formed on a portion of the front surface opposite the back-side conductor pattern. A sensing layer is formed over all or a portion of the floating back-side conductor pattern.

A bulk acoustic wave resonator is provided. The resonator includes a substrate; a resonant portion including a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate; and a temperature compensation layer disposed at least one of above and below the piezoelectric layer, wherein a material of the temperature compensation layer has a coefficient of thermal expansion of which a sign is opposite to a sign of a coefficient of thermal expansion of a material of the piezoelectric layer, and wherein a relation of a thickness of the temperature compensation layer and a thickness of the piezoelectric layer satisfies the following equation: 0.25<Thickness of Temperature Compensation Layer/Thickness of Piezoelectric Layer<0.33.

Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A bulk acoustic wave (BAW) resonator may comprise a substrate and a first layer of piezoelectric material having a first piezoelectric axis orientation. The bulk acoustic wave (BAW) resonator may comprise a multi-layer acoustic reflector, e.g., a multi-layer metal top acoustic reflector electrode, including a first pair of top metal electrode layers. The first pair of top metal electrode layers may be electrically and acoustically coupled with the first layer of piezoelectric material to excite a piezoelectrically excitable resonance mode at a resonant frequency of the BAW resonator.