Abstract: A manufacturing method for a boundary acoustic wave device is capable of certainly providing the boundary acoustic wave device with desired target frequency characteristics. The manufacturing method for the boundary acoustic wave device includes a process for preparing a laminated body that includes a first medium, a second medium laminated on the first medium, and an IDT electrode that is disposed at an interface between the first and second media, and a process for implanting ions from an outer portion of the second medium and adjusting a frequency.

Abstract: An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

Abstract: An elastic wave device includes a lithium niobate film, a supporting substrate, a high-acoustic-velocity film located on the supporting substrate and configured so that the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave that propagates on the lithium niobate film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and configured so that the acoustic velocity of the propagating bulk wave is lower than the acoustic velocity of the bulk wave that propagates in the lithium niobate film, the lithium niobate film being stacked on the low-acoustic-velocity film, and an IDT electrode located on either side of the lithium niobate film. When the lithium niobate film has Euler angles of (0°±5°, ?, 0°), ? is in the range of about 0° to about 8° and about 57° to about 180°.

Abstract: A frequency-variable filter includes a filter unit and matching circuits. The filter unit includes frequency-variable resonance circuits that include piezoelectric resonators. The matching circuits have a circuit configuration in which a real number component of an impedance increases as the frequency increases. For example, the matching circuits have an L-type circuit configuration that includes a reactance element connected in shunt to the side of the filter unit and that includes an inductor and a capacitor. As the filter unit includes the piezoelectric resonators, the real number component of the impedance increases as the pass band shifts to a high-frequency side, but the real number component of the impedance increases as the frequency increases in the matching circuits as well.

Abstract: A resonant circuit includes a resonator having a resonant frequency and an anti-resonant frequency, an inductor connected in series to the resonator, an inductor connected in parallel to the resonator, and a series circuit in which a variable capacitor is connected in series to an inductor (15). The series circuit is connected in parallel to the resonator. The anti-resonant frequency closest to the resonant frequency of the resonator is moved toward higher frequencies or lower frequencies of the resonant frequency on a frequency axis with a variation in the capacitance value of the variable capacitor. With this configuration, a resonator device and a high-frequency filter are provided, in which the relationship between a transmission frequency band and a reception frequency band on the frequency axis is applicable to a variety of multiple communication bands.

Abstract: A method for manufacturing a composite piezoelectric substrate capable of forming an ultra-thin piezoelectric film includes preparing a piezoelectric substrate and a supporting substrate, implanting ions from a surface of the piezoelectric substrate to form a defective layer in a region of the piezoelectric substrate, removing impurities that are adhered to at least one of the surface of the piezoelectric substrate in which the defective layer is formed and a surface of the supporting substrate to directly expose the constituent atoms of the surfaces and to activate the surfaces, bonding the supporting substrate to the surface of the piezoelectric substrate to form a bonded substrate body, and separating the bonded substrate body at the defective layer formed in the piezoelectric substrate so that a separation layer between the surface of the piezoelectric substrate and the defective layer is separated from the piezoelectric substrate.

Abstract: A tunable filter using Love waves includes an inductance for band extension connected to each of piezoelectric resonators, variable capacitances are connected to the piezoelectric resonator, the piezoelectric resonators each include a LiNbO3 substrate and an IDT electrode, and a pass band and an attenuation region are positioned in a frequency region on a lower frequency side relative to a value obtained by a calculation in which an acoustic velocity of a low-velocity transversal wave propagating in the LiNbO3 substrate is divided by a wave length defined by a period of the IDT electrode.

Abstract: In a surface acoustic wave device, a plurality of surface acoustic wave elements include piezoelectric bodies having the same cut-angle. A propagation azimuth of a surface acoustic wave in at least one of surface acoustic wave elements is different from a propagation azimuth of a surface acoustic wave in at least another one of the surface acoustic wave elements. In each of the surface acoustic wave elements, a confinement layer configured to confine the surface acoustic wave inside the piezoelectric body is disposed on the piezoelectric body at the side opposite to the side where an electrode is located.

Abstract: An ion implantation layer is formed in a piezoelectric single crystal substrate by implanting hydrogen ions. A lower electrode is formed on the surface of the piezoelectric single crystal substrate at a side at which the ion implantation layer is formed. A sacrificial layer is formed on the surface of the piezoelectric single crystal substrate at a side at which the ion implantation layer and the lower electrode are formed. The formation of the sacrificial layer is performed by direct formation thereof on the surface of the piezoelectric single crystal substrate, for example, by sputtering or coating. A support layer is formed on the piezoelectric single crystal substrate on which the sacrificial layer is formed, and after the surface of the support layer is planarized, a support base material is bonded thereto.

Abstract: An elastic wave device includes a medium layer, a piezoelectric body, and an IDT electrode that are disposed on a supporting substrate. The medium layer is made of a medium containing a low-velocity medium in which a propagation velocity of a same bulk wave as that which is a main vibration component of an elastic wave propagating in the piezoelectric body and being used is lower than a propagation velocity of the elastic wave, and a high-velocity medium in which the propagation velocity of the same bulk wave as that which is a main vibration component of the elastic wave is higher than the propagation velocity of the elastic wave.

Abstract: A method for manufacturing a composite piezoelectric substrate in which a piezoelectric substrate and a supporting substrate are prepared, ions are implanted in the piezoelectric substrate to form a defective layer at a predetermined depth in the piezoelectric substrate, impurities that are adhered to a surface of the piezoelectric substrate or a surface of the supporting substrate are removed to expose the constituent atoms thereof and to activate the surfaces, the supporting substrate is bonded to the piezoelectric substrate to form a bonded substrate body, the bonded substrate body is separated at the defective layer so that a separation layer between the surface of the piezoelectric substrate and the defective layer is separated from the piezoelectric substrate and bonded to the supporting substrate to form a composite piezoelectric substrate, and the surface of the separation layer of the composite piezoelectric substrate is smoothed.

Abstract: An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

Abstract: An elastic wave device includes a lithium niobate film, a supporting substrate, a high-acoustic-velocity film located on the supporting substrate and configured so that the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave that propagates on the lithium niobate film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and configured so that the acoustic velocity of the propagating bulk wave is lower than the acoustic velocity of the bulk wave that propagates in the lithium niobate film, the lithium niobate film being stacked on the low-acoustic-velocity film, and an IDT electrode located on either side of the lithium niobate film. When the lithium niobate film has Euler angles of (0°±5°, ?, 0°), ? is in the range of about 0° to about 8° and about 57° to about 180°.

Abstract: A method for producing a piezoelectric composite substrate having a single-crystal thin film of a piezoelectric material includes an ion-implantation step and a separation step. In the ion-implantation step, He+ ions are implanted into the single-crystal base made of the piezoelectric material to form localized microcavities in a separation layer located inside the single-crystal base and apart from a surface of the single-crystal base. In the separation step, the microcavities formed in the ion-implantation step are subjected to thermal stress to divide the separation layer of the piezoelectric single-crystal base, thereby detaching the single-crystal thin film.

Abstract: In a surface acoustic wave device, a plurality of surface acoustic wave elements include piezoelectric bodies having the same cut-angle. A propagation azimuth of a surface acoustic wave in at least one of surface acoustic wave elements is different from a propagation azimuth of a surface acoustic wave in at least another one of the surface acoustic wave elements. In each of the surface acoustic wave elements, a confinement layer configured to confine the surface acoustic wave inside the piezoelectric body is disposed on the piezoelectric body at the side opposite to the side where an electrode is located.

Abstract: An elastic wave device includes a medium layer, a piezoelectric body, and an IDT electrode that are disposed on a supporting substrate. The medium layer is made of a medium containing a low-velocity medium in which a propagation velocity of a same bulk wave as that which is a main vibration component of an elastic wave propagating in the piezoelectric body and being used is lower than a propagation velocity of the elastic wave, and a high-velocity medium in which the propagation velocity of the same bulk wave as that which is a main vibration component of the elastic wave is higher than the propagation velocity of the elastic wave.

Abstract: A method for manufacturing a composite substrate that prevents undesirable effects of etching a thin film includes a pattern forming step, an ion implanting step, a bonding step, and a separation step. In the pattern forming step, a pattern region and a reverse pattern region are formed on a principal surface of a functional material substrate. In the ion implanting step, by implanting ions into the functional material substrate, a separation layer is formed inside at a certain distance from the surface of each of the pattern region and the reverse pattern region. In the bonding step, the functional material substrate at the pattern region is bonded to a supporting substrate. In the separation step, the pattern region is separated from the functional material substrate, and the reverse pattern region is made to fall off.

Abstract: A piezoelectric bulk wave device that includes a piezoelectric thin plate that is made of LiTaO3, and first and second electrodes that are provided in contact with the piezoelectric thin plate. The piezoelectric bulk wave device utilizes the thickness shear mode of the piezoelectric thin plate made of LiTaO3. The first and second electrodes are each formed by a conductor having a specific acoustic impedance higher than the specific acoustic impedance of a transversal wave that propagates in LiTaO3. When the sum of the film thicknesses of the first and second electrodes is defined as an electrode thickness, and the thickness of the piezoelectric thin plate made of LiTaO3 is defined as an LT thickness, the electrode thickness/(electrode thickness+LT thickness) is in the range of not less than 40% and not more than 95%.

Abstract: In a method for manufacturing a composite piezoelectric substrate, a piezoelectric substrate and a supporting substrate are prepared, ions are implanted from a surface of the piezoelectric substrate to form a defective layer at a predetermined depth, impurities adhered to the surface of the piezoelectric substrate in which the defective layer is formed and/or a surface of the supporting substrate are removed to directly expose the constituent atoms of the surfaces and activate the surfaces, the supporting substrate is bonded to the piezoelectric substrate to form a bonded substrate body, the bonded substrate body is separated at the defective layer so that a separation layer between the surface of the piezoelectric substrate and the defective layer is separated from the piezoelectric substrate and bonded to the supporting substrate to form a composite piezoelectric substrate, and the surface of the separation layer of the composite piezoelectric substrate is smoothed.

Abstract: A piezoelectric bulk wave device that includes a piezoelectric thin plate that is made of LiTaO3, and first and second electrodes that are provided in contact with the piezoelectric thin plate. The piezoelectric bulk wave device utilizes the thickness shear mode of the piezoelectric thin plate made of LiTaO3. The first and second electrodes are each formed by a conductor having a specific acoustic impedance higher than the specific acoustic impedance of a transversal wave that propagates in LiTaO3. When the sum of the film thicknesses of the first and second electrodes is defined as an electrode thickness, and the thickness of the piezoelectric thin plate made of LiTaO3 is defined as an LT thickness, the electrode thickness/(electrode thickness+LT thickness) is not less than 5% and not more than 40%.