A bulk acoustic wave resonator includes: a substrate; a membrane layer forming a cavity together with the substrate; a lower electrode disposed on the membrane layer; a piezoelectric layer disposed on a flat surface of the lower electrode; and an upper electrode covering a portion of the piezoelectric layer and exposing a side of the piezoelectric layer to air, wherein the piezoelectric layer includes a step portion extended from the side of the piezoelectric layer and disposed on the flat surface of the lower electrode.

An acoustic resonator includes a substrate, an insulation layer disposed on the substrate, a resonating portion disposed on the insulation layer and having a first electrode, a piezoelectric layer, and a second electrode, stacked thereon, a cavity disposed between the insulation layer and the resonating portion, a protruded portion having a plurality of protrusions disposed on a lower surface of the cavity, and a hydrophobic layer disposed on an upper surface of the cavity and a surface of the protruded portion.

Provided are a solidly mounted resonator and a method for preparing a solidly mounted resonator. The solidly mounted resonator includes: a piezoelectric structure, wherein the piezoelectric structure includes: an upper electrode layer, a lower electrode layer and a piezoelectric layer. The lower electrode layer disposed corresponding to the piezoelectric structure, and the lower electrode layer includes: a protruding portion protruding downward corresponding to a lower surface of the lower electrode layer; the piezoelectric layer is disposed on an upper surface of the lower electrode layer; the upper electrode layer is disposed on an upper surface of the piezoelectric layer.

The present disclosure relates to a piezoelectric single-crystal element, a MEMS device using same, and a method for manufacturing same, wherein the piezoelectric single-crystal element includes a wafer, a lower electrode stacked on the wafer, a piezoelectric single-crystal thin film stacked on the lower electrode, and an upper electrode stacked on the piezoelectric single-crystal thin film, wherein the piezoelectric single-crystal thin film is composed of PMN-PT, PIN-PMN-PT or Mn:PIN-PMN-PT, and the piezoelectric single-crystal thin film has a polarization direction set to a <001> axis, a <011> axis or a <111> axis, and a MEMS device using same.

An acoustic wave resonator for use in a device for wireless communications includes a first electrode, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode. The first electrode has a first region made of a material having a first density, and a second region formed as a loop region surrounding the first region and electrically connected to the first region. The second region is made of a material having a second density that is different from the first density.

The vibrator element includes a base part, a vibrating arm extending from the base part, and a weight provided to the vibrating arm, wherein the weight includes a thick film part, a thin film part thinner in film thickness than the thick film part, and a connection part which is located between the thick film part and the thin film part to connect the thick film part and the thin film part to each other, and which forms a taper shape gradually decreasing in film thickness in a direction from the thick film part side toward the thin film part.

A laterally excited bulk acoustic wave device is disclosed. The laterally excited bulk acoustic wave device can include a first solid acoustic mirror, a second solid acoustic mirror, a piezoelectric layer that is positioned between the first solid acoustic mirror and the second solid acoustic mirror, an interdigital transducer electrode on the piezoelectric layer, and a support substrate arranged to dissipate heat associated with the bulk acoustic wave. The interdigital transducer electrode is arranged to laterally excite a bulk acoustic wave. The first solid acoustic mirror and the second solid acoustic mirror are arranged to confine acoustic energy of the bulk acoustic wave. The first solid acoustic mirror is positioned on the support substrate.

An acoustic wave device includes an IDT electrode with an inclined IDT structure on a piezoelectric substrate. An intersection region, where a first electrode finger and a second electrode finger overlap each other when viewed in an acoustic wave propagation direction, includes a central region and first and second low acoustic velocity regions on both sides of the central region. The first and second low acoustic velocity regions have an asymmetric shape about a central axis extending in a length direction of the first and second electrode fingers.

The present disclosure provides a piezoelectric resonator comprising a substrate having an acoustic reflection mirror, a bottom electrode stacked on the substrate, a piezoelectric layer disposed on the substrate and covering the bottom electrode, and a top electrode stacked on a surface of piezoelectric layer distal to the bottom electrode. An overlapping portion of the acoustic reflection mirror, the bottom electrode, the piezoelectric layer, and the top electrode along a thickness direction of the piezoelectric resonator is a resonance region. A sidewall of the top electrode or a bottom electrode recesses to form a recessing portion. The recessing portion does not extend to an upper surface or a lower surface of the top electrode or the bottom electrode.

A resonator circuit device. The present invention provides for improved resonator shapes using egg-shaped, partial egg-shaped, and asymmetrical partial egg-shaped resonator structures. These resonator shapes are configured to give less spurious mode/noise below the resonant frequency (F.sub.s) than rectangular, circular, and elliptical resonator shapes. These improved resonator shapes also provide filter layout flexibility, which allows for more compact resonator devices compared to resonator devices using conventionally shaped resonators.