An acoustic wave device comprises a substrate including a piezoelectric material, interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate. The IDT electrodes having gap regions, edge regions, and center regions. A duty factor of the IDT electrodes in the edge regions is greater than the duty factor of the IDT electrodes in the center regions. A first dielectric film is disposed above the IDT electrodes and an upper surface of the substrate. The first dielectric film has a greater thickness in portions of the center regions than in portions proximate the gap regions.

A surface acoustic wave resonator comprises at least one set of interdigital transducer (IDT) electrodes disposed on an upper surface of a piezoelectric substrate between first and second reflector gratings, a layer of silicon nitride disposed over the at least one set of IDT electrodes and the first and second reflector gratings, and a continuous trench formed in the layer of silicon nitride over portions of bus bar electrodes and tips of electrode fingers of the at least one set of IDT electrodes and over portions of bus bar electrodes and electrode fingers of the first and second reflector gratings to reduce acoustic leakage at electrode fingers of the first and second reflector gratings proximate the at least one set of IDT electrodes.

A longitudinally coupled resonator acoustic wave filter includes first, second, and third IDT electrodes disposed on a piezoelectric substrate. The first, second, and third IDT electrodes include first electrode fingers and second electrode fingers. The first, second, and third IDT electrodes include narrow-pitch electrode finger portions in which the pitch between electrode fingers is narrower than in the remaining electrode finger portions. In the first, second, and third IDT electrodes, an overlap area includes a central area and first and second edge areas at opposite ends of the central area in the direction in which the first and second electrode fingers extend. In the remaining electrode finger portions the first electrode fingers and the second electrode fingers include wide portions in the first or second edge area.

There are disclosed acoustic resonators and method of fabricating acoustic resonators. An acoustic resonator includes a single-crystal piezoelectric plate having front and back surfaces, the back surface attached to a surface of a substrate except for portions of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. A conductor pattern on the front surface includes an interdigital transducer (IDT) with interleaved fingers of the IDT disposed on the diaphragm. A periodic array of holes is provided in the diaphragm.

An acoustic wave device includes an IDT electrode provided on a piezoelectric substrate. The IDT electrode includes a crossing area including a central area, and first and second low-acoustic-velocity areas on both sides in a direction perpendicular or substantially perpendicular to an acoustic wave propagating direction. First and second high-acoustic-velocity areas are provided outside the first and second low-acoustic-velocity areas. Mass adding films are laminated in respective portions of first and second electrode fingers, the respective portions being positioned in the first and second low-acoustic-velocity areas. In at least one of the mass adding films, a width of a first end portion and a width of a second end portion are narrower than a width of a central portion, and a protruding portion protrudes from at least one of the first and second end portions.

An elastic wave device includes a piezoelectric substrate including an IDT electrode provided on one main surface. In the elastic wave device, a center region positioned in a central portion in a direction perpendicular to an elastic wave propagation direction, first and second low acoustic velocity regions positioned outside of the center region, and first and second high acoustic velocity regions positioned outside of the first and the second low acoustic velocity regions in plan view are provided. A groove portion overlaps with one of the first electrode finger and the second electrode finger in plan view in a portion located in the first and second low acoustic velocity regions on the main surface. An acoustic velocity adjusting layer is provided in the groove portion.

An acoustic wave device utilizes Love waves and includes a piezoelectric substrate (piezoelectric body), an IDT electrode provided on the piezoelectric substrate, and a first dielectric film that is provided on the piezoelectric substrate and covers the IDT electrode. A center region, first and second edge regions, and first and second gap regions are disposed in this order in the IDT electrode. A mass-adding film is provided inside the first dielectric film in the first edge region and the second edge region. When T1 is the film thickness of the portion of the first dielectric film located between the IDT electrode and the mass-adding film and T2 is the film thickness of the portion of the first dielectric film located between the mass-adding film and the surface of the first dielectric film on the opposite side from the piezoelectric substrate, T1/(T1+T2)<about 0.5.

An acoustic wave device includes a plurality of interdigital transducer electrodes, in a first interdigital transducer electrode, a first electrode finger includes a wide portion having a greater width in the second direction than a center portion. In the first interdigital transducer electrode, for the first electrode finger, a first distance that is a maximum distance in the second direction between a center line of the center portion in a first direction is shorter than a second distance that is a maximum distance in a second direction between the center line of the center portion and an outer edge, away from a second interdigital transducer electrode, of the wide portion.

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 elastic wave device includes an IDT electrode provided on a piezoelectric substrate and including a first end region including one end of the IDT electrode in an elastic wave propagation direction, a second end region including the other end of the IDT electrode in the elastic wave propagation direction, and an inner region that is located farther toward an inside than the first and second end regions in the elastic wave propagation direction, includes first and second high-acoustic-velocity regions, and a center region and first and second low-acoustic-velocity regions, located in the crossing region. The mass of the IDT electrode in the crossing region in the first and second end regions is smaller than the mass of the IDT electrode in the crossing region in the inner region.