Aspects of this disclosure relate to a surface acoustic wave device. The surface acoustic wave device includes a piezoelectric layer and an interdigital transducer. The interdigital transducer electrode includes a pair of electrodes, each electrode having a bus bar and fingers extending from the bus bar. The interdigital transducer electrode has an interdigital region defined by a portion of the fingers of the electrodes that interdigitate with each other. A dielectric layer is disposed over the interdigital transducer electrode outside the interdigital region and configured to reduce a loss of the surface acoustic wave device.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer that is positioned partially between the piezoelectric layer and the interdigital transducer electrode. The dielectric layer that is positioned so as to partially electro-mechanically de-couple the piezoelectric layer from the interdigital transducer electrode.

An acoustic wave device includes a piezoelectric substrate, functional elements, an outer peripheral support layer, a cover portion, and a protective layer covering the cover portion. A hollow space is defined by the piezoelectric substrate, the outer peripheral support layer, and the cover portion, and the functional elements are disposed in the hollow space. The acoustic wave device further includes an under bump metal layer, a wiring pattern, and a through-electrode that connects these elements. In the protective layer, a through-hole to be filled with a conductor to electrically connect a solder ball and the under bump metal layer is provided. The outer peripheral support layer includes a protruding portion protruding to the hollow space. When the acoustic wave device is seen in plan view, at least a portion of the through-hole overlaps the hollow space, and an end portion of the protruding portion overlaps an inner region of the through-hole.

An acoustic wave resonator comprises a carrier substrate, a layer of dielectric material disposed on an upper surface of the carrier substrate, and a layer of piezoelectric material disposed above the layer of dielectric material. The layer of piezoelectric material includes a pair of opposing terminating edges that are coterminous with the layer of dielectric material. One or more interdigital transducers (IDTs) are disposed on the layer of piezoelectric material. The opposing terminating edges sandwich the one or more interdigital transducers, and in some examples, a pair of reflector gratings disposed on the layer of piezoelectric material and each including less than eight reflector fingers. The opposing terminating edges provide edge reflections that allow a reduction in size or a complete removal of the reflector gratings, resulting in a smaller acoustic wave resonator compared to conventional devices while maintaining a comparable performance.

An acoustic wave device includes a semiconductor support including a principal surface, a piezoelectric layer on the principal surface of the semiconductor support, and an IDT electrode on a principal surface of the piezoelectric layer. The IDT electrode includes first and second busbars, and first and second electrode fingers. The IDT electrode includes first gaps between the first busbar and respective second electrode fingers. A recess is provided in at least a portion of the semiconductor support substrate overlapping the first gaps as viewed in plan. No recess is provided in at least a portion of the semiconductor support substrate overlapping the IDT electrode as viewed in plan. The recess opens toward the piezoelectric layer.

An acoustic wave device includes an interdigital transducer electrode connected to first and second terminals, and a reflector connected to the second terminal. In a group of electrode fingers of the interdigital transducer electrode, the electrode fingers at one end and another end in a second direction are respectively first and second end electrode fingers, the first end electrode finger includes a wide portion at a distal end portion. The first end electrode finger is located between the reflector and the second end electrode finger in the second direction. An inner busbar portion of one of first and second busbars not connected to the first end electrode finger, is located on an inner side in the second direction relative to the wide portion of the first end electrode finger so as not to overlap the wide portion of the first end electrode finger in a first direction.

An acoustic wave device includes a piezoelectric substrate a reverse-velocity surface of which is convex, an interdigital transducer electrode disposed on the piezoelectric substrate, and mass addition films stacked above the interdigital transducer electrode. The interdigital transducer electrode includes a central region, first and second edge regions, first and second gap regions located outside the first and second edge regions, first and second inner busbar regions, and first and second outer busbar regions. The mass addition films are stacked in at least the first and second edge regions and the first and second inner busbar regions.

An acoustic wave device includes a support substrate, a low-acoustic-velocity film on the support substrate, a piezoelectric layer on the low-acoustic-velocity film, an IDT electrode on the piezoelectric layer, and a high-acoustic-velocity film between the support substrate and the low-acoustic-velocity film. An acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer. An acoustic velocity of a bulk wave propagating though the high-acoustic-velocity film is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer. Adhesion between the low-acoustic-velocity film and the support substrate is higher than adhesion between the high-acoustic-velocity film and the support substrate. The high-acoustic-velocity film is between portions of the support substrate and the low-acoustic-velocity film, and a portion of the low-acoustic-velocity film and a portion of the support substrate contact each other.

An acoustic wave device includes a support including a cavity, a piezoelectric layer on or above the support and made of one of lithium niobate or lithium tantalate, an interdigital transducer electrode embedded in the piezoelectric layer and including surfaces opposed to each other in a thickness direction, one of the surfaces being in contact with the piezoelectric layer, and a dielectric film on the piezoelectric layer and covering the interdigital transducer electrode. The interdigital transducer electrode includes electrode fingers, at least one of which overlaps the cavity in plan view. Assuming a thickness of the piezoelectric layer is d and an electrode finger pitch of the interdigital transducer electrode is p, p/d≥ about 4.25.

An interdigital transducer for a surface-acoustic-wave resonator includes a conductive grid and a plurality of practical electrodes. The conductive grid includes a bus bar, a plurality of dummy electrodes and a conductive bar. The bus bar has a signal transmission terminal, and is disposed on a first side of the first conductive grid. The plurality of dummy electrodes directly extend from the bus bar. The conductive bar is disposed on a second side of the first conductive grid, and is opposite to the bus bar. Each of the plurality of practical electrodes extends from the conductive bar.