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 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 filter device includes a substrate, first and second acoustic impedance layers, a piezoelectric layer, first and second interdigital transducer electrodes, an input terminal, an output terminal, ground terminals, a series arm circuit, and a parallel arm circuits. The first interdigital transducer electrode at least partially overlaps the first acoustic impedance layer in the plan view. The second interdigital transducer electrode at least partially overlaps the second acoustic impedance layer in the plan view. The series arm circuit is provided on a first path connecting the input terminal and the output terminal and includes the first and second interdigital transducer electrodes. A conductive layer in the first acoustic impedance layer and a conductive layer in the second acoustic impedance layer are electrically insulated from each other.

Abstract: In an elastic wave device, a piezoelectric substrate is stacked on a support substrate and an IDT electrode is provided on the piezoelectric substrate. Wiring line portions are provided on the piezoelectric substrate. A first hollow portion is provided in the support substrate at least below at least one of the wiring line portions and or below a region between the wiring line portions.

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: A composite device includes a silicon substrate including first and second main surfaces on opposite sides, a semiconductor device adjacent to at least one of the first and second main surfaces, and an acoustic wave device including a silicon oxide film directly or indirectly disposed on the first main surface of the silicon substrate, a piezoelectric layer directly disposed on the silicon oxide film, and an IDT disposed on the piezoelectric layer. The piezoelectric layer has a thickness of not greater than about 2.5? where ? is a wavelength defined by an electrode finger pitch of the IDT.

Abstract: In an elastic wave device, a piezoelectric substrate is laminated on a support substrate including a recess. On one of a first principal surface and a second principal surface of the piezoelectric substrate, a functional electrode including an IDT electrode is provided. Passing-through sections are provided in the piezoelectric substrate and connected to a hollow section enclosed by the recess and the piezoelectric substrate. In a plan view of the piezoelectric substrate seen from the first principal surface, at least a portion of the passing-through sections is inside a minimum rectangular or substantially rectangular region encompassing an outer circumference of a region including the functional electrode.

Abstract: A composite device includes a silicon substrate including first and second main surfaces on opposite sides, a semiconductor device adjacent to at least one of the first and second main surfaces, and an acoustic wave device including a silicon oxide film directly or indirectly disposed on the first main surface of the silicon substrate, a piezoelectric layer directly disposed on the silicon oxide film, and an IDT disposed on the piezoelectric layer. The piezoelectric layer has a thickness of not greater than about 2.5? where ? is a wavelength defined by an electrode finger pitch of the IDT.

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: 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 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 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 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.

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: A piezoelectric member that achieves a high sound speed includes a silicon-containing substrate and a piezoelectric layer. The piezoelectric layer is disposed on the silicon-containing substrate. At least a surface layer of the piezoelectric layer on a side opposite to the silicon-containing substrate is made of BxAl1-xN (0<x?0.2).

Abstract: In an elastic wave device, a piezoelectric substrate is laminated on a support substrate including a recess. On one of a first principal surface and a second principal surface of the piezoelectric substrate, a functional electrode including an IDT electrode is provided. Passing-through sections are provided in the piezoelectric substrate and connected to a hollow section enclosed by the recess and the piezoelectric substrate. In a plan view of the piezoelectric substrate seen from the first principal surface, at least a portion of the passing-through sections is inside a minimum rectangular or substantially rectangular region encompassing an outer circumference of a region including the functional electrode.

Abstract: In an elastic wave device, a piezoelectric substrate is stacked on a support substrate and an IDT electrode is provided on the piezoelectric substrate. Wiring line portions are provided on the piezoelectric substrate. A first hollow portion is provided in the support substrate at least below at least one of the wiring line portions and or below a region between the wiring line portions.

Abstract: A piezoelectric member that achieves a high sound speed includes a silicon-containing substrate and a piezoelectric layer. The piezoelectric layer is disposed on the silicon-containing substrate. At least a surface layer of the piezoelectric layer on a side opposite to the silicon-containing substrate is made of BxAl1-xN (0<x?0.2).

Abstract: A method for manufacturing a surface acoustic wave element that prevents curvature of a piezoelectric substrate when forming an electrode pattern includes a first step of bonding to a first principal surface of a piezoelectric substrate a support member having a linear expansion coefficient lower than a linear expansion coefficient of the piezoelectric substrate to form a composite substrate, a second step of forming a plurality of grooves in the support member of the composite substrate from a surface that is opposite to a bonding interface between the support member and the piezoelectric substrate, a third step of forming electrode patterns including at least one IDT electrode on a second principal surface of the piezoelectric substrate of the composite substrate, and a fourth step of dividing the composite substrate on which the electrode patterns are formed to form individual surface acoustic wave elements.

Abstract: A small-sized elastic wave apparatus in which heat generated at a portion of a cascade connection between resonators is sufficiently dissipated includes on one main surface of a piezoelectric substrate in an elastic wave filter mounted on a base substrate on which an input/output wiring line, a ground wiring line, and a floating wiring line insulated from the input/output wiring line and the ground wiring line are provided, first electrodes coupled to the input/output wiring line or the ground wiring line, second electrodes coupled to the floating wiring line, resonators, connection wiring lines connecting the resonators, and electrode wiring lines connecting the resonators and the first electrodes. The second electrodes are disposed in contact with the connection wiring lines cascading the resonators.