Abstract: An acoustic wave device includes a support, a piezoelectric layer with an anisotropic coefficient of linear expansion, and including first and second main surfaces, at least one through-hole, a first electrode in or on the first main surface, and a second electrode in or on the second main surface and opposed to the first electrode. A cavity is provided in the support. At least a portion of the first and second electrodes overlaps the cavity in plan view. In plan view, the at least one through-hole is line symmetric about an axis of symmetry that passes a center of the cavity in a region where the first and second electrodes overlap each other and that extends in a direction in which the coefficient of linear expansion of the piezoelectric layer is greatest.

Abstract: An acoustic wave device includes a first layer including a support substrate, a second layer on the first layer and including a piezoelectric film, and a first excitation electrode on the second layer. A cavity is between the first and second layers, and the first excitation electrode at least partially overlaps the cavity in a stacking direction of the first and second layers. A surface roughness of a major surface of the first layer facing the cavity is different from a surface roughness of a major surface of the second layer facing the cavity.

Abstract: An acoustic wave device includes an intermediate film, a piezoelectric film 4, and a first electrode, which are laminated in this order on a support substrate. A void portion is provided to overlap at least a part of the first electrode on the side of a second main surface of the piezoelectric film in plan view from the side of a first main surface. A groove portion is also provided to pass through at least a part of the piezoelectric film but not reach the void portion.

Abstract: An acoustic wave device that includes a piezoelectric substrate that has a piezoelectric layer and a hollow portion, and first and second electrodes and. The piezoelectric layer has a first region that overlaps the first and second electrodes and the hollow portion in plan view, a second region that does not overlap the hollow portion and surrounds the first region in plan view, and a third region that overlaps the hollow portion and is located between the first region and the second region in plan view. A portion including the border between the first region and the third region of a cross-sectional shape in a lamination direction of the piezoelectric substrate includes a curved-surface shape.

Abstract: An acoustic wave device includes a supporting substrate, an acoustic reflection layer, a piezoelectric layer, and an IDT electrode. At least one of a high acoustic impedance layer and a low acoustic impedance layer is a conductive layer in the acoustic reflection layer. When a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is ? and a region between an envelope of tips of first electrode fingers and an envelope of tips of second electrode fingers is an intersecting region, the conductive layer overlaps at least the intersecting region in plan view in a thickness direction of the supporting substrate, and a distance from the tips of the first electrode fingers to an end of the conductive layer in a direction in which the first electrode fingers extend is more than 0 and not more than about 12?.

Abstract: An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. An absolute value of a thermal expansion coefficient of the piezoelectric substrate is larger than an absolute value of a thermal expansion coefficient of the supporting substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the first acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the third acoustic impedance layer and the fourth acoustic impedance layer.

Abstract: An acoustic wave device includes a substrate, first and second resonators above the substrate, and an energy confinement portion. The first resonator includes a first piezoelectric film including a first main surface facing a second main surface, both having anisotropy. First and second electrodes are provided on the first or second main surface. The second resonator includes a second piezoelectric film including a third main surface facing a fourth main surface, both having anisotropy. Third and fourth electrodes are provided on the third or fourth main surface. In the first resonator, a first excitation portion is where the first and second electrodes overlap or where the first electrode faces the second electrode. In the second resonator, a second excitation portion is where the third and fourth electrodes overlap or where the third electrode faces the fourth electrode. The first and second excitation portions have shapes including length directions that differ.

Abstract: An acoustic wave device includes a support substrate, and a piezoelectric layer provided on the support substrate. The piezoelectric layer has a first main surface opposite to a second main surface. The piezoelectric layer also includes a first direction orthogonal to a second direction. A first electrode is provided on the piezoelectric layer's first main surface, and a second electrode is provided on the piezoelectric layer's second main surface to face the first electrode. An energy confining portion is provided between the support substrate and the piezoelectric layer. The piezoelectric layer is anisotropic with respect to a coefficient of linear expansion, and in the piezoelectric layer, a coefficient of linear expansion in the first direction is different from a coefficient of linear expansion in the second direction. At least one of the piezoelectric layer, the first electrode, and the second electrode is parallel to the first direction.

Abstract: An acoustic wave device includes a support substrate, a dielectric film, a piezoelectric layer, and an excitation electrode. The piezoelectric layer includes first and second main surfaces. The second main surface is on a side including the dielectric film. A cavity portion is provided in the dielectric film and overlaps at least a portion of the excitation electrode in plan view. The dielectric film includes a side wall surface facing the cavity portion and including an inclined portion inclined so that a width of the cavity portion decreases with increasing distance away from the piezoelectric layer. The inclined portion includes at least an end portion on a side including the piezoelectric layer, in the side wall surface. When an angle between the inclined portion and the second main surface of the piezoelectric layer is defined as an inclination angle ?, the inclination angle ? is from about 40° to about 80° inclusive.

Abstract: An elastic wave device includes a supporting substrate including an upper surface including a recessed portion, a piezoelectric thin film on the supporting substrate to cover the recessed portion of the supporting substrate, an IDT electrode on a main surface of the piezoelectric thin film, the main surface being adjacent to the supporting substrate, and an intermediate layer on a main surface of the piezoelectric thin film, the main surface being remote from the supporting substrate. A space is defined by the supporting substrate and the piezoelectric thin film. The IDT electrode faces the space. Through holes are provided in the piezoelectric thin film and the intermediate layer to extend from a main surface of the intermediate layer to the space, the main surface being remote from the piezoelectric thin film. The elastic wave device further includes a cover member on the intermediate layer and covering opening ends of the through holes.

Abstract: In a piezoelectric device, when viewed in a direction perpendicular to one main surface, an outer shape of a recess is a polygonal shape or a circular shape. When n represents a number of sides of the polygonal shape, r represents a radius of a circumscribed circle of an imaginary regular polygon including n sides with a length identical to a length of a shortest of the sides, and d represents a maximum thickness of a membrane portion, which is located above the recess, of a multilayer portion, r?197.7dn?0.6698 when 3?n?7, and r?52.69d when 8?n or when the outer shape of the recess is a circular shape.

Abstract: An acoustic wave device includes first and second IDT electrodes electrically connected in series with each other by a common busbar common to the first and second IDT electrodes. In each of a first acoustic impedance layer and a second acoustic impedance layer, at least one of at least one high acoustic impedance layer and at least one low acoustic impedance layer is a conductive layer. At least a portion of the conductive layer in the first acoustic impedance layer and at least a portion of the conductive layer in the second acoustic impedance layer do not overlap with the common busbar when viewed in plan from a thickness direction of a piezoelectric layer. The conductive layer in the first acoustic impedance layer and the conductive layer in the second acoustic impedance layer are electrically insulated from each other.

Abstract: An acoustic wave device includes a piezoelectric member, a first and second electrodes on first and second main surfaces of the piezoelectric member, an acoustic reflection section including an air gap, and an additional mass film in at least one of areas on the first and second electrodes and an area outward of the first or second electrodes. A region where at least one of the first electrode and the additional mass film overlaps the second electrode includes a first region and a second region surrounding the first region. In the second region, a configuration of additional mass film portions on corresponding sides of a first direction in a plane of the piezoelectric member and a configuration of additional mass film portions on corresponding sides of a second direction in the plane of the piezoelectric member are different from each other.

Abstract: An acoustic wave device includes a first acoustic impedance layer and a second acoustic impedance layer, an IDT electrode, and an electrode. At least a portion of the IDT electrode overlaps the first acoustic impedance layer. At least a portion of the electrode overlaps the second acoustic impedance layer. In each of the first acoustic impedance layer and the second acoustic impedance layer, at least one of a high acoustic impedance layer and a low acoustic impedance layer is a conductive layer. A capacitor is formed by using the conductive layer of the second acoustic impedance layer and the electrode. The conductive layer in the first acoustic impedance layer is electrically insulated from the conductive layer in the second acoustic impedance layer.

Abstract: An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The at least four acoustic impedance layers include at least one low acoustic impedance layer and at least one high acoustic impedance layer having an acoustic impedance higher than the low acoustic impedance layer. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the acoustic impedance layer, which is the fourth acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the acoustic multilayer film and the supporting substrate.

Abstract: An elastic wave device in which an IDT electrode defines an excitation electrode on a piezoelectric layer, an acoustic reflection layer is laminated on a first main surface of the piezoelectric layer, the acoustic reflection layer includes high acoustic impedance layers with a relatively high acoustic impedance and low acoustic impedance layers with a relatively low acoustic impedance, and the acoustic reflection layer has an unwanted wave reflection suppression structure in which reflection of unwanted waves toward the piezoelectric layer side is significantly reduced or prevented.

Abstract: An acoustic wave device includes a supporting substrate, an acoustic reflection layer, a piezoelectric layer, and an IDT electrode. At least one of a high acoustic impedance layer and a low acoustic impedance layer is a conductive layer in the acoustic reflection layer. When a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is ? and a region between an envelope of tips of first electrode fingers and an envelope of tips of second electrode fingers is an intersecting region, the conductive layer overlaps at least the intersecting region in plan view in a thickness direction of the supporting substrate, and a distance from the tips of the first electrode fingers to an end of the conductive layer in a direction in which the first electrode fingers extend is more than 0 and not more than about 12?.

Abstract: An elastic wave device includes an interdigital transducer electrode including electrode fingers provided on a first principal surface of a piezoelectric thin film. A conductive layer is provided on a second principal surface of the piezoelectric thin film. An elastic wave propagates in the piezoelectric thin film in an S0 mode of a plate wave, and a piezoelectric thin film portion in a region below spaces between the electrode fingers of the interdigital transducer electrode is displaced by a greater amount than each electrode finger and a piezoelectric thin film portion in a region below each electrode finger.

Abstract: An acoustic wave device includes a supporting substrate, an acoustic reflection film the supporting substrate, a piezoelectric thin film on the acoustic reflection film, and an interdigital transducer electrode the piezoelectric thin film. The acoustic reflection film includes acoustic impedance layers including therein first, second, third, and fourth low acoustic impedance layers and first, second, and third high acoustic impedance layers. The acoustic reflection film includes a first acoustic impedance layer and a second acoustic impedance layer, the first and second acoustic impedance layers each being one of the acoustic impedance layers, and the second acoustic impedance layer has an arithmetic average roughness different from that of the first acoustic impedance layer.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric laminate, and first and second interdigital transducer electrodes. The piezoelectric laminate includes an intermediate layer provided directly or indirectly on the support substrate and a piezoelectric thin film provided on the intermediate layer. The first and second interdigital transducer electrodes are provided on the piezoelectric thin film of the piezoelectric laminate so as to be disposed in an identical or substantially identical plane. In the piezoelectric laminate, a thickness of a portion where the first interdigital transducer electrode is provided is different from a thickness of a portion where the second interdigital transducer electrode is provided.