Abstract: An acoustic wave device includes an IDT electrode on a piezoelectric substrate and reflector electrodes on both sides of the IDT electrode in an acoustic wave propagation direction and each including electrode fingers with gaps therebetween, and first dielectric films between the reflector electrodes and the piezoelectric substrate in regions where the electrode fingers and the gaps of the reflector electrodes are provided.

Abstract: An acoustic wave device including an IDT electrode on a piezoelectric film, in which a Z-axis direction of a crystal is different from a direction of a normal to a major surface. An overlap region of the IDT electrode includes a central region and first and second edge regions. First and second dielectric films are stacked between the piezoelectric film and first and second electrode fingers in the first and second edge regions. When an angle between a first side surface of the first dielectric film and a major surface of the piezoelectric film is ?1 and an angle between a second side surface of the second dielectric film and the major surface of the piezoelectric film is ?2, ?1??2 between at least one electrode finger of the first and second electrode fingers and the piezoelectric film.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode. The IDT electrode includes a center area and first and second edge areas. Areas including the first and second edge areas and overlapping the areas in an acoustic-wave propagation direction include first and second expansion edge areas. First and second acoustic-velocity adjusters are provided in the first and second expansion edge areas. The first and second acoustic-velocity adjusters respectively includes first and second end portions and third and fourth end portions. The first to fourth end portions are located at outer sides of the first and second edge areas. End portions in at least one of two pairs including a pair of first and third end portions and a pair of second and fourth end portions do not overlap each other in a direction in which electrode fingers extend.

Abstract: An acoustic wave device includes a piezoelectric substrate including a support and a piezoelectric layer made of lithium tantalate or lithium niobate, a functional electrode on the piezoelectric layer and including a pair of electrode fingers, and a dielectric film on the piezoelectric layer and covering the pair of electrode fingers. An acoustic reflection portion overlaps the functional electrode in plan view. In a case where a thickness of the piezoelectric layer is d and a center-to-center distance between the electrode fingers adjacent to each other is p, d/p is about 0.5 or less. The electrode fingers include first and second surfaces facing each other, and a side surface connected to the first and second surfaces. The second surface is located on a side of the piezoelectric layer.

Abstract: An acoustic wave device includes a support including a support substrate, a piezoelectric layer on the support, and an IDT electrode including busbars and electrode fingers, and a mass-adding film on the piezoelectric layer. In plan view as seen in a stacking direction in which the support and the piezoelectric layer are stacked, an acoustic reflector overlaps at least a portion of the IDT electrode. d/p is less than or equal to about 0.5, where d is a thickness of the piezoelectric layer and p is a center-to-center distance between adjacent electrode fingers. A region in which adjacent electrode fingers overlap each other when seen from an electrode-finger-facing direction is a crossing region. Regions between the crossing region and the pair of busbars include first and second gap regions. The mass-adding film overlaps the gap region in plan view and is on the second main surface of the piezoelectric layer.

Abstract: A piezoelectric device includes a support substrate, an intermediate layer on the support substrate, a piezoelectric layer on the intermediate layer, a functional element on the piezoelectric layer, an insulation layer, and a wiring electrode. The insulation layer is on the support substrate and in contact with the intermediate layer and the piezoelectric layer. The wiring electrode extends from a top of the insulation layer to a top of the piezoelectric layer and is connected to the functional element. The insulation layer includes first and second regions. The first region is thinner than a thickness of the multilayer body. The second region connects the first region and the multilayer body, and includes a portion slanted from the first region toward an upper surface of the piezoelectric layer. The second region of the insulation layer does not extend to the top of the piezoelectric layer.

Abstract: An acoustic wave device includes a silicon substrate, a first high-acoustic-velocity film on the silicon substrate, a first low-acoustic-velocity film on the first high-acoustic-velocity film, a second low-acoustic-velocity film on the first low-acoustic-velocity film, a second high-acoustic-velocity film on the second low-acoustic-velocity film, a piezoelectric film on the second high-acoustic-velocity film, and an IDT electrode on the piezoelectric film. Acoustic velocities of bulk waves propagating through the first and second high-acoustic-velocity films are higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric film. Acoustic velocities of bulk waves propagating through the first and second low-acoustic-velocity films are lower than an acoustic velocity of a bulk wave propagating through the piezoelectric film. Materials of the first and second low-acoustic-velocity films are different from each other.

Abstract: An acoustic wave device includes a piezoelectric layer including first and second main surfaces, an IDT electrode on one of the first and second main surfaces, and including electrode fingers, a support facing the second main surface, and including an acoustic reflection portion at a portion closer to the second main surface of the piezoelectric layer, and a load film extending over a region that overlaps, when viewed in plan in the first direction, at least electrode fingers from a fourth one of the electrode fingers from a first outer end in an arrangement direction to a fourth one of the electrode fingers from a second outer end in the arrangement direction. d/p is less than or equal to about 0.5 where d denotes a thickness of the piezoelectric layer, and p denotes a center-to-center distance between adjacent two of the electrode fingers.

Abstract: An acoustic wave device includes a piezoelectric layer including a first main surface and a second main surface facing the first main surface in a first direction, an IDT electrode on at least one of the first main surface and the second main surface of the piezoelectric layer and including electrode fingers arranged in an arrangement direction, a reflector adjacent to the IDT electrode in the arrangement direction of the electrode fingers, a support that faces the second main surface of the piezoelectric layer and includes an acoustic reflection portion on a side of the second main surface of the piezoelectric layer, and a load film provided in a region overlapping with the reflector in a plan view from the first direction. When a thickness of the piezoelectric layer is d and a distance between centers of the adjacent electrode fingers is p, d/p is about 0.5 or less.

Abstract: An acoustic wave device includes a piezoelectric layer including first and second main surfaces facing in a first direction, an IDT electrode on at least one of the first or second main surface and including electrode fingers arranged in an arrangement direction, a support facing the second main surface and including an acoustic reflection portion, and a protective film on at least one of the first or second main surface. In a region that overlaps, in plan view in the first direction, a first of the electrode fingers outermost in the arrangement direction, the protective film includes a surface of a first step where a side surface of the protective film is exposed in a direction intersecting an extending direction of the first electrode finger. When d is a thickness of the piezoelectric layer and p is a center-to-center distance between adjacent electrode fingers, d/p is about 0.5 or less.

Abstract: An acoustic wave device includes a piezoelectric layer including first and second major surfaces, an IDT electrode on one of the first and second major surfaces, and including electrode fingers arranged in an arrangement direction, and a support facing the second major surface, and including an acoustic reflection portion facing the second major surface. The electrode fingers include a first electrode finger at an outermost position in the arrangement direction and a second electrode finger adjacent thereto. A product of a width, height, and density of one of the first and second electrode fingers is greater than a product of a width, height, and density of a central electrode finger. When the thickness of the piezoelectric layer is denoted by d and a center-to-center distance between adjacent electrode fingers is denoted by p, d/p is less than or equal to about 0.5.

Abstract: An acoustic wave device includes a piezoelectric layer including first and second main surfaces, an IDT electrode on at least one of the first and second main surfaces and including electrode fingers arranged in a predetermined direction, and a support facing the second main surface and including an acoustic reflection portion toward the second main surface. At least one of a first electrode finger in an outermost portion and a second electrode finger internally adjacent to the first electrode finger differs from central electrode fingers inside the second electrode finger in at least one of a dimension in a direction orthogonal to an extension direction and an inter-center distance to an internally adjacent electrode finger, d/p is about 0.5 or less, where d denotes a thickness of the piezoelectric layer and p denotes the inter-center distance between adjacent electrode fingers.

Abstract: An acoustic wave device includes a piezoelectric layer with first and second major surfaces, an IDT electrode on at least one of the first and second major surfaces and including electrode fingers arranged in a predetermined direction, a support facing the second major surface and including an acoustic reflection portion on the second major surface side, and a load film in a region that, in plan view in a first direction, overlaps at least one end portion of the IDT electrode in the arrangement direction. The end portion includes a first electrode finger positioned outermost in the arrangement direction, and d/p is about 0.5 or less where d is a thickness of the piezoelectric layer and p is a center-to-center distance between adjacent ones of the electrode fingers.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, and at least one lithium niobate layer and first and second principal surfaces opposed to each other, and first and second IDT electrodes respectively on the first and second principal surfaces. Each of the first and second IDT electrodes includes electrode fingers. A duty ratio of each of the first and second IDT electrodes is equal to or greater than about 0.6. Directions of polarization of the piezoelectric layer are inverted in a thickness direction of the piezoelectric layer.

Abstract: An acoustic wave device includes a support substrate, a quartz-crystal layer provided directly or indirectly on the support substrate, a piezoelectric layer on the quartz-crystal layer, and an IDT electrode on the piezoelectric layer. When ? represents a wavelength defined by an electrode finger pitch of the IDT electrode, a thickness of the quartz-crystal layer is about 0.2? or more and about 0.4? or less, and the piezoelectric layer has a thickness smaller than the thickness of the quartz-crystal layer.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate and including electrode fingers. A portion where adjacent electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction is an intersecting region. The intersecting region includes a central region located in a central portion in a direction in which the electrode fingers extend and first and second edge regions on both sides of the central region in the direction in which the electrode fingers extend. The acoustic wave device further includes dielectric films between the piezoelectric substrate and the electrode fingers in the first and second edge regions. The dielectric films include at least one of hafnium oxide, niobium oxide, tungsten oxide, or cerium oxide.

Abstract: An elastic wave device includes a support substrate, a piezoelectric film directly or indirectly provided on the support substrate, and an IDT electrode on the piezoelectric film. The piezoelectric film includes a first piezoelectric film in which a surface facing the support substrate is a plus surface and a surface facing the IDT electrode is a minus surface, and a second piezoelectric film in which a surface facing the support substrate is a minus surface and a surface facing the IDT electrode is a plus surface, the second piezoelectric film being disposed on the first piezoelectric film. A total of the thickness of the first piezoelectric film and the thickness of the second piezoelectric film is about 1? or less where ? represents a wavelength determined by an electrode finger pitch of the IDT electrode.

Abstract: An acoustic wave device includes a support substrate including a first crystal axis, first and second intermediate layers, a piezoelectric layer including a second crystal axis, and a functional electrode on the piezoelectric layer. The support substrate, the first and second intermediate layers, and the piezoelectric layer are arranged in this order. The first crystal axis is inclined at a first inclination angle with respect to a direction normal to the support substrate. The second crystal axis is inclined at a second inclination angle with respect to a direction normal to the piezoelectric layer. The first and second inclination angles are equal to each other. Rotational symmetry of the piezoelectric layer with respect to the second crystal axis is equal to rotational symmetry of the support substrate with respect to the first crystal axis.

Abstract: A piezoelectric device includes a support substrate, an intermediate layer on the support substrate in a first region, a piezoelectric layer on the intermediate layer, a functional element on the piezoelectric layer, and an insulating layer. The insulating layer is located on the support substrate in a second region adjacent to the first region. A surface roughness of the support substrate in the second region is greater than a surface roughness of the support substrate in the first region.

Abstract: An acoustic wave device includes a support substrate, a first high acoustic velocity film on the support substrate, a low acoustic velocity film on the first high acoustic velocity film, a second high acoustic velocity film on the low acoustic velocity film, a piezoelectric layer on the second high acoustic velocity film, and an IDT on the piezoelectric layer. Bulk waves propagate in the low acoustic velocity film more slowly than bulk waves propagate in the piezoelectric layer, bulk waves propagate in the first high acoustic velocity film faster than acoustic waves propagate on the piezoelectric layer, and bulk waves propagate in the second high acoustic velocity film faster than or as fast as bulk waves propagate in the first high acoustic velocity film.