Abstract: A composite substrate that is obtained by bonding a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate as a support substrate, and thinning the piezoelectric material substrate after the bonding.

Abstract: A method for manufacturing a composite substrate includes: forming a first intermediate layer including thermally synthesized silica on a surface of a support substrate; forming a second intermediate layer including an inorganic material on a surface of a piezoelectric single crystal substrate; flattening a surface of the second intermediate layer; and bonding a surface of the first intermediate layer to the flattened surface of the second intermediate layer.

Abstract: Manufacturing methods for a composite substrate for surface acoustic wave devices with improved characteristics is provided. The composite substrate for a surface acoustic wave device is configured to include a piezoelectric single crystal substrate and a supporting substrate. An intervening layer is provided between the piezoelectric single crystal substrate and the supporting substrate, the amount of chemisorbed water in the intervening layer is 1×1020 molecules/cm3 or less. At the bonding interface between the piezoelectric single crystal substrate and the supporting substrate, at least one of the piezoelectric single crystal substrate and the supporting substrate may have an uneven structure. It is preferable that the ratio of the average length RSm of the element in the sectional curve of the uneven structure and the wavelength ? of the surface acoustic wave when used as a surface acoustic wave device is 0.2 or more and 7.0 or less.

Abstract: A method of manufacturing a composite substrate that includes bonding a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate as a support substrate, and thinning the piezoelectric material substrate after the bonding. The piezoelectric material substrate is particularly preferably a lithium tantalate wafer (LT) substrate or a lithium niobate (LN) substrate.

Abstract: There are provided a method for manufacturing a substrate excellent in heat dissipation with a small loss in radio frequencies with no need of a high temperature process in which a metal impurity is diffused, and a substrate of high thermal conductivity. A composite substrate according to the present invention is a composite substrate having a piezoelectric single crystal substrate, a support substrate, and an intermediate layer provided between the piezoelectric single crystal substrate and the support substrate. The intermediate layer is a film formed of an inorganic material, and at least a part of the film is thermally synthesized silica. The intermediate layer may be separated into at least two layers along the bonding surface of the composite substrate. The first intermediate layer in contact with the support substrate may be a layer including thermally synthesized silica.

Abstract: A composite substrate is resistant to the development of cracks, thereby not having deteriorating properties even when exposed to high-temperatures or low temperatures, and a method is provided for producing the composite substrate. The composite substrate 10 of the present invention has a supporting substrate 2, a stress relaxing interlayer 3, and an oxide single-crystal thin film 1 stacked in the listed order. The stress relaxing interlayer 3 has a thermal expansion coefficient between that of the supporting substrate 2 and that of the oxide single-crystal thin film 1.

Abstract: Provided is a composite substrate for surface acoustic wave device which does not cause peeling of an entire surface of a piezoelectric single crystal film even when heating the film to 400° C. or higher in a step after bonding. The composite substrate is formed by providing a piezoelectric single crystal substrate and a support substrate, forming a film made of an inorganic material on at least one of the piezoelectric single crystal substrate and the support substrate, and joining the piezoelectric single crystal substrate with the support substrate so as to sandwich the film made of the inorganic material.

Abstract: A laminated structure includes a crystalline substrate and a crystalline oxide film containing gallium as a main component and having a ?-gallia structure, wherein the crystalline substrate is a crystalline substrate containing lithium tantalate as a main component. This provides an inexpensive laminated structure having a thermally stable crystalline oxide film.

Abstract: A composite substrate includes a single crystal support substrate containing first element as a main component; an oxide single crystal layer provided on the single crystal support substrate and containing a second element (excluding oxygen) as a main component; and an amorphous layer provided in between the single crystal support substrate and the oxide single crystal layer and containing a first element, a second element, and Ar, the amorphous layer having a first amorphous region in which proportion of the first element is higher than proportion of the second element, and a second amorphous region in which the proportion of the second element is higher than the proportion of the first element, concentration of Ar contained in the first amorphous region being higher than concentration of Ar contained in the second amorphous region and being 3 atom % or more.

Abstract: A piezoelectric composite substrate for SAW devices with small loss is provided. A composite substrate for a surface acoustic wave device according to one embodiment of the present invention has a piezoelectric single crystal thin film, a support substrate, and a first intervening layer between the piezoelectric single crystal thin film and the support substrate. In said composite substrate, the first intervening layer is in contact with the piezoelectric single crystal thin film, and the acoustic velocity of the transverse wave in the first intervening layer is faster than the acoustic velocity of the fast transverse wave in the piezoelectric single crystal thin film.

Abstract: To provide a method for producing a composite wafer capable of reducing a spurious arising by reflection of an incident signal on a joint interface between a lithium tantalate film and a supporting substrate, in the composite wafer including a supporting substrate having a low coefficient of thermal expansion, and a lithium tantalate film having a high coefficient of thermal expansion stacked on the supporting substrate. The method for producing a composite wafer is a method for producing a composite wafer that produces a composite wafer by bonding a lithium tantalate wafer having a high coefficient of thermal expansion to a supporting wafer having a low coefficient of thermal expansion, wherein prior to bonding together, ions are implanted from a bonding surface of the lithium tantalate wafer and/or the supporting wafer, to disturb crystallinity near the respective bonding surfaces.

Abstract: An object of the present invention is to provide a bonded substrate which is excellent in temperature characteristics and suppresses unnecessary response due to reflection of an elastic wave at a bonding interface. [Means to Solve the Problems] The present invention is unique in that a bonded substrate is constructed by bonding a LiTaO3 substrate and a base plate wherein a Li concentration at a base plate-bonding face of the LiTaO3 substrate is higher than that at a LiTaO3 substrate-side end face of the bonded substrate, that the difference between the Li concentration at the base plate-bonding face of the LiTaO3 substrate and the Li concentration at the LiTaO3 substrate-side end face of the bonded substrate is 0.1 mol % or greater, that the Li concentration at the base plate-bonding face of the LiTaO3 substrate satisfies an equation Li/(Li+Ta)×100=(50+?) mol %, where ? is in the range of ?1.2<?<0.

Abstract: [Object] It is an object of the present invention to provide a lithium tantalate single crystal substrate which undergoes only small warpage, is free from cracks and scratches, has better temperature non-dependence characteristics and a larger electromechanical coupling coefficient than a conventional Y-cut LiTaO3 substrate.

Abstract: Provided is a high-performance composite substrate for surface acoustic wave device which has good temperature characteristics and in which spurious caused by the reflection of a wave on a joined interface between a piezoelectric crystal film and a support substrate is reduced. The composite substrate for surface acoustic wave device includes: a piezoelectric single crystal substrate; and a support substrate, where, at a portion of a joined interface between the piezoelectric single crystal substrate and the support substrate, at least one of the piezoelectric single crystal substrate and the support substrate has an uneven structure, a ratio of an average length RSm of elements in a cross-sectional curve of the uneven structure to a wavelength ? of a surface acoustic wave when the substrate is used as a surface acoustic wave device is equal to or more than 0.2 and equal to or less than 7.0.

Abstract: A composite substrate for surface acoustic wave devices with improved characteristics is provided. The composite substrate for a surface acoustic wave device according to the present invention is configured to include a piezoelectric single crystal substrate and a supporting substrate. An intervening layer is provided between the piezoelectric single crystal substrate and the supporting substrate, the amount of chemisorbed water in the intervening layer is 1×1020 molecules/cm3 or less. At the bonding interface between the piezoelectric single crystal substrate and the supporting substrate, at least one of the piezoelectric single crystal substrate and the supporting substrate may have an uneven structure. It is preferable that the ratio of the average length RSm of the element in the sectional curve of the uneven structure and the wavelength ? of the surface acoustic wave when used as a surface acoustic wave device is 0.2 or more and 7.0 or less.

Abstract: An object of the present invention is to provide a method of manufacturing a composite substrate including a piezoelectric layer with less Li amount variation and a support substrate. A method of manufacturing a composite substrate of the present invention includes a step of performing ion implantation into a piezoelectric substrate, a step of bonding the piezoelectric substrate and the support substrate, a step of separating the bonded substrate, at an ion-implanted portion of the piezoelectric substrate, into the piezoelectric layer bonded to the support substrate and the remaining piezoelectric substrate after the step of bonding the piezoelectric substrate and the support substrate, and a step of diffusing Li into the piezoelectric layer after the separating step.

Abstract: A lithium tantalate single crystal substrate for a surface acoustic wave device that is a rotated Y-cut LiTaO3 substrate whose crystal orientation has a Y-cut angle of not smaller than 36° and not larger than 49° and which has such a Li concentration profile after diffusion of Li into the substrate from the surface thereof that the Li concentration at the surface of the substrate differs from that inside the substrate. A shear vertical type elastic wave whose main components are vibrations in the thickness direction and in the propagation direction and which is among those elastic waves which propagate in the X axis direction within the surface of this LiTaO3 substrate has an acoustic velocity of not lower than 3140 m/s and not higher than 3200 m/s.

Abstract: Provided is a composite substrate for a surface acoustic wave device in which a chip is hardly generated at an outer peripheral edge of an electric material layer and peeling is hardly generated from the outer peripheral edge. The composite substrate for a surface acoustic wave device is a composite substrate in which a piezoelectric material single crystal thin film and a supporting substrate are bonded at a bonding surface. The supporting substrate has a closed first contour line, the bonding surface has a closed second contour line, and the piezoelectric material single crystal thin film has a closed third contour line. When the first contour line and the third contour line are projected perpendicularly to a plane including the bonding surface, the projection image of the first contour line is located outside the second contour line, and the projection image of the third contour line is located inside the second contour line.

Abstract: There are provided a method for manufacturing a substrate excellent in heat dissipation with a small loss in radio frequencies with no need of a high temperature process in which a metal impurity is diffused, and a substrate of high thermal conductivity. A composite substrate according to the present invention is a composite substrate having a piezoelectric single crystal substrate, a support substrate, and an intermediate layer provided between the piezoelectric single crystal substrate and the support substrate. The intermediate layer is a film formed of an inorganic material, and at least a part of the film is thermally synthesized silica. The intermediate layer may be separated into at least two layers along the bonding surface of the composite substrate. The first intermediate layer in contact with the support substrate may be a layer including thermally synthesized silica.

Abstract: An object of the present invention is to provide a method of manufacturing a composite substrate including a piezoelectric layer with less Li amount variation and a support substrate. A method of manufacturing a composite substrate of the present invention includes a step of performing ion implantation into a piezoelectric substrate, a step of bonding the piezoelectric substrate and the support substrate, a step of separating the bonded substrate, at an ion-implanted portion of the piezoelectric substrate, into the piezoelectric layer bonded to the support substrate and the remaining piezoelectric substrate after the step of bonding the piezoelectric substrate and the support substrate, and a step of diffusing Li into the piezoelectric layer after the separating step.