Abstract: An elastic wave device that utilizes a longitudinal wave leaky elastic wave includes a first medium layer, a second medium layer stacked on the first medium layer either directly or indirectly and that is a silicon oxide layer, a piezoelectric film stacked on the second medium layer either directly or indirectly, and an IDT electrode disposed on the piezoelectric film either directly or indirectly. In the elastic wave device, ?1×C11, which is a product of a density ?1 (kg/m3) of the first medium layer and an elastic constant C11 of the first medium layer, is larger than ?0×C11, which is a product of a density ?0 (kg/m3) of the piezoelectric film and an elastic constant C11 of the piezoelectric film.

Abstract: A piezoelectric transducer includes beam portions each with a fixed end portion and extending in a direction away from the fixed end portion. A base portion is connected to the fixed end portion of each of the beam portions. The beam portions extends in a same plane, and respective extending directions of at least two beam portions are different from each other. The beam portions each include a single crystal piezoelectric layer having a polarization axis in a same direction, an upper electrode layer, and a lower electrode layer. A polarization axis has a polarization component in the plane. An axial direction of an orthogonal axis that is orthogonal to the polarization axis and extends in the above-described plane intersects with an extending direction of each of the plurality of beam portions.

Abstract: A MEMS device includes a membrane portion, a piezoelectric layer made of a piezoelectric single crystal, a first electrode on a first surface of the piezoelectric layer, a second electrode on a second surface of the piezoelectric layer opposite to the first direction, and a first layer covering the first surface of the piezoelectric layer. At least a portion of the piezoelectric layer is included in the membrane portion. Each of the first electrode and the second electrode has a tapered cross-sectional shape with a width which decreases with increasing distance from the piezoelectric layer on a cross section along a plane vertical to the surface in the first direction.

Abstract: A piezoelectric device includes a membrane portion and a piezoelectric layer made of single crystal of a piezoelectric body. At least a portion of the piezoelectric layer is included in the membrane portion. An electrode is provided on a surface of the piezoelectric layer in the membrane portion. The piezoelectric layer includes a first polarization region in a first polarization state and a second polarization region in a second polarization state, and the first polarization region and the second polarization region are spaced apart from each other in a thickness direction or an in-plane direction.

Abstract: A MEMS device includes a piezoelectric layer made of a piezoelectric single crystal, a first electrode on a first surface of the piezoelectric layer, and a first layer covering the first surface of the piezoelectric layer. At least a portion of the piezoelectric layer is included in a membrane portion. The first electrode is covered with the first layer and includes a recess. The piezoelectric layer includes a through hole that passes through the piezoelectric layer between a surface of the piezoelectric layer, which is opposite to the first direction, and the recess at a position corresponding to at least a portion of the first electrode.

Abstract: A piezoelectric device includes a base portion and a membrane portion. The membrane portion is indirectly supported by the base portion, and is located on the upper side relative to the base portion. The membrane portion includes a plurality of layers. The membrane portion does not overlap with the base portion, and includes a single crystal piezoelectric layer, an upper electrode layer, and a lower electrode layer. The membrane portion is provided with a through-groove penetrating in the up-down direction. The through-groove includes a first step portion provided in the thickest layer among the plurality of layers defining the membrane portion. The width of the through-groove is narrower on a lower side than on an upper side with the first step portion as a boundary.

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 elastic wave device in which a recess is provided on an upper side of a support, a piezoelectric thin film covers the recess, and an IDT electrode is provided on an upper surface of the piezoelectric thin film. A plate wave of an S0 mode or SH0 mode is used. A plurality of grooves are provided in the upper surface or lower surface of the piezoelectric thin film at a portion of the piezoelectric thin film that is positioned on a hollow section.

Abstract: In a piezoelectric device, electrode layers are spaced apart from each other in the direction of the normal thereto. A first piezoelectric layer is interposed between two electrode layers of electrode layers in the direction of the normal. A second piezoelectric layer is provided on an opposite side of the first piezoelectric layer from a base portion. The second piezoelectric layer is interposed between two electrode layers of the electrode layers in the direction of the normal. The half-width of a rocking curve measured by X-ray diffraction for a lattice plane of the first piezoelectric layer substantially parallel to a first main surface is smaller than a half-width for the second piezoelectric layer. The piezoelectric constant of a material defining the first piezoelectric layer is smaller than the piezoelectric constant of a material defining the second piezoelectric layer.

Abstract: In a method of manufacturing a piezoelectric device in which a piezoelectric thin film on which functional conductors are formed is fixed to a support substrate by a fixing layer, an alignment mark is formed on one main surface of a light-transmitting piezoelectric substrate. A sacrificial layer is formed on a main surface of the piezoelectric substrate with reference to the alignment mark and the fixing layer is formed so as to cover the sacrificial layer and is bonded to the support substrate. The piezoelectric thin film is formed by being separated from the piezoelectric substrate and the functional conductors are formed on the surface of the piezoelectric thin film with reference to the alignment mark. The piezoelectric device is able to be manufactured while positions of formation regions of conductors are adjusted efficiently.

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 elastic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes a busbar electrode extending in an elastic wave propagation direction and electrode fingers connected to the busbar electrode and extending in a direction perpendicular or substantially perpendicular to the elastic wave propagation direction. The piezoelectric substrate includes a groove extending along the elastic wave propagation direction. The groove is provided on a side across the busbar electrode in the perpendicular or substantially perpendicular direction from a side at which the electrode fingers are located.

Abstract: An elastic wave device in which a recess is provided on an upper side of a support, a piezoelectric thin film covers the recess, and an IDT electrode is provided on an upper surface of the piezoelectric thin film. A plate wave of an S0 mode or SH0 mode is used. A plurality of grooves are provided in the upper surface or lower surface of the piezoelectric thin film at a portion of the piezoelectric thin film that is positioned on a hollow section.

Abstract: An acoustic wave device includes a silicon support substrate that includes first and second main surfaces opposing each other, a piezoelectric structure provided on the first main surface and including the piezoelectric layer, an IDT electrode provided on the piezoelectric layer, a support layer provided on the first main surface of the silicon support substrate and surrounding the piezoelectric layer, a cover layer provided on the support layer, a through-via electrode that extending through the silicon support substrate and the piezoelectric structure, and a first wiring electrode connected to the through-via electrode and electrically connected to the IDT electrode. The piezoelectric structure includes at least one layer having an insulating property, the at least one layer including the piezoelectric layer. The first wiring electrode is provided on the layer having an insulating property in the piezoelectric structure.

Abstract: In an acoustic wave device, a piezoelectric body is directly or indirectly laminated on a silicon support substrate, and a functional electrode is provided on the piezoelectric body. A support layer is directly or indirectly laminated on the silicon support substrate, and the support layer is located outside the functional electrode when viewed in plan view. A silicon cover layer is provided on the support layer that includes an insulating material, and a space A is defined by the silicon support substrate, the support layer, and the silicon cover layer. The electric resistance of the silicon support substrate is higher than the electric resistance of the silicon cover layer.

Abstract: An acoustic wave device includes a piezoelectric substrate including a support substrate and a piezoelectric layer on the support substrate, the piezoelectric substrate including a first principal surface on the piezoelectric layer side, and a second principal surface on the support substrate side, an IDT electrode on the first principal surface, a support layer on the support substrate, a cover on the support layer, a through-via electrode provided through the support substrate and electrically connected to the IDT electrode, a first wiring electrode on the second principal surface of the piezoelectric substrate and electrically connected to the through-via electrode, and a protective film on the second principal surface to cover at least a portion of the first wiring electrode. The protective film is provided on an inner side of the support layer when viewed in a direction normal or substantially normal to the second principal surface.

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: A piezoelectric resonator includes a piezoelectric thin film including a functional conductor, a fixing layer provided on a principal surface of the piezoelectric thin film to define a void that overlaps a functional portion region, and a support substrate on a principal surface of the fixing layer. A sacrificial layer is provided on a principal surface of a piezoelectric substrate and the fixing layer is provided on the principal surface of the piezoelectric substrate to cover the sacrificial layer. The support substrate is attached to a surface of the fixing layer and the piezoelectric thin film is peeled from the piezoelectric substrate. The functional conductor is provided on the piezoelectric thin film, a through hole is provided in the piezoelectric thin film to straddle a boundary between the fixing layer and the sacrificial layer, and the sacrificial layer is removed by wet etching using the through hole to form the void.

Abstract: A piezoelectric device includes a piezoelectric single crystal body with a homogeneous polarization state and of which at least a portion flexurally vibrates, an upper electrode on an upper surface of the piezoelectric single crystal body, a lower electrode on a lower surface of the piezoelectric single crystal body, and a supporting substrate below the piezoelectric single crystal body. A recess extends from a lower surface of the supporting substrate toward the lower surface of the piezoelectric single crystal body.

Abstract: A piezoelectric device includes a piezoelectric body at least a portion of which can bend and vibrate, an upper electrode on an upper surface of the piezoelectric body and in which distortion of a crystal lattice is reduced as a distance from the upper surface of the piezoelectric body increases, a lower electrode on a lower surface of the piezoelectric body and in which distortion of a crystal lattice is reduced as a distance from the upper surface of the piezoelectric body increases, and a support substrate below the piezoelectric body, in which a recess extending from a lower surface of the support substrate toward the lower surface of the piezoelectric device is provided.