An acoustic wave resonator includes two comb-shaped electrodes provided on a piezoelectric substrate, each of the comb-shaped electrodes including electrode fingers and a bus bar coupled to the electrode fingers, an acoustic velocity of an acoustic wave propagating through a gap region, which is located between tips of electrode fingers of one of the comb-shaped electrodes and a bus bar of the other of the comb-shaped electrodes, being equal to or greater than 0.98 times and equal to or less than 1.02 times an acoustic velocity of an acoustic wave propagating through an edge region located in an edge in an extension direction of the electrode fingers in an overlap region, and an additional film that is provided over the piezoelectric substrate from the edge region to the gap region and is not provided in a center region located further in than the edge region in the overlap region.

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 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.

A filter device includes a substrate having piezoelectricity, a first filter including an IDT electrode disposed on the substrate, a terminal electrode disposed on the substrate, a first wiring electrode disposed on the substrate and connecting the first filter and a terminal electrode, and a dielectric film disposed above the substrate to cover the IDT electrode. At least a portion of the first wiring electrode is not covered with the dielectric film.

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.

An acoustic wave device can include a substrate, a piezoelectric layer, a first electrode that includes a first bus bar and a first plurality of fingers extending from the first bus bar, and a second electrode that includes a second bus bar and a second plurality of fingers extending from the second bus bar. The second plurality of fingers can be interdigitated with the first plurality of fingers. The acoustic wave device can include a raised frame structure. The raised frame structure can be configured to suppress a transverse mode. The fingers can have widths that are greater than the distances between the fingers. The acoustic wave device can include a bus bar that includes a main section and a secondary section that are electrically connected by gap lines, which can have smaller width than the fingers. The acoustic wave device can include dummy fingers.

A method of making a surface acoustic wave package includes bonding a piezoelectric layer over a substrate and attaching a metal structure over the substrate, with the piezoelectric layer positioned between at least a portion of the substrate and at least a portion of the metal structure. The method also includes removing (e.g., etching) an outer boundary of the piezoelectric layer so that a resulting outer edge of the piezoelectric layer is spaced inward of an inner edge of the metal package (e.g., the piezoelectric layer does not contact the metal package). The method inhibit damage to the piezoelectric layer due to a stress differential between the substrate and the thermally conductive structure during a packaging process.

An acoustic wave element includes an IDT electrode including a plurality of electrode fingers and exciting a surface acoustic wave, a first substrate including an upper surface on which the IDT electrode is located, the first substrate being configured by a piezoelectric crystal, and a second substrate bonded to a side where a lower surface of the first substrate is located. Either of a first region which continues from the lower surface of the first substrate toward a side where the upper surface is located or a second region which continues from the lower surface of the first substrate toward a side where the second substrate is located is a low resistance region having a resistance value of 5×10.sup.3Ω to 5×10.sup.7Ω.