A composite substrate production method of the invention includes (a) a step of mirror polishing a substrate stack having a diameter of 4 inch or more, the substrate stack including a piezoelectric substrate and a support substrate bonded to each other, the mirror polishing being performed on the piezoelectric substrate side until the thickness of the piezoelectric substrate reaches 3 m or less; (b) a step of creating data of the distribution of the thickness of the mirror-polished piezoelectric substrate; and (c) a step of performing machining with an ion beam machine based on the data of the thickness distribution so as to produce a composite substrate have some special technical features.

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.

An elastic wave device includes IDT electrodes on a first main surface of a piezoelectric substrate and a heat dissipating film on a second main surface and including a pair of opposing main surfaces and side surfaces connecting the pair of main surfaces. At least a portion of the side surfaces of the heat dissipating film is located in an inner side portion relative to the outer circumference of the second main surface of the piezoelectric substrate on an arbitrary cross section along a direction connecting the pair of main surfaces of the heat dissipating film.

A method of manufacturing a piezoelectric structure comprises providing a substrate of piezoelectric material, providing a carrier substrate, depositing a dielectric bonding layer at a temperature lower than or equal to 300 C. on a single side of the substrate of piezoelectric material, a step of joining the substrate of piezoelectric material to the carrier substrate via the dielectric bonding layer, a thinning step for forming the piezoelectric structure, which comprises a layer of piezoelectric material joined to a carrier substrate.

A method of manufacturing a piezoelectric structure comprises providing a substrate of piezoelectric material, providing a carrier substrate, depositing a dielectric bonding layer at a temperature lower than or equal to 300 C. on a single side of the substrate of piezoelectric material, a step of joining the substrate of piezoelectric material to the carrier substrate via the dielectric bonding layer, a thinning step for forming the piezoelectric structure, which comprises a layer of piezoelectric material joined to a carrier substrate.

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.

A composite substrate according to the present invention includes a support substrate having a diameter of 2 inches or more, and a piezoelectric substrate having a thickness of 20 m or less and bonded to the support substrate to transmit light. The piezoelectric substrate has a thickness distribution shaped like a fringe. A waveform having an amplitude within a range of 5 to 100 nm in a thickness direction and a pitch within a range of 0.5 to 20 mm in a width direction appears in the thickness distribution of the piezoelectric substrate in a cross section of the composite substrate taken along a line orthogonal to the fringe, and the pitch of the waveform correlates with a width of the fringe. In the piezoelectric substrate, the fringe may include either parallel fringes or spiral or concentric fringes.

A manufacturing method of a vibrator includes processing a tip of a contact part arranged on an elastic body of the vibrator by lapping or grinding processing so that part of the tip has a plane shape in part of a spherical shape.

An electronic device includes a first substrate and a second substrate. A side wall joins the first substrate to the second substrate. The side wall includes a first alloy layer of a first metal and a second metal bonded directly to an upper surface of the first substrate and a second alloy layer of the first metal and a third metal disposed on top of the first alloy layer and bonded directly to a lower surface of the second substrate, the second metal and the third metal being different from each other and from the first metal. An electronic circuit is disposed on the lower surface of the second substrate within a cavity defined by the lower surface of the first substrate, the upper surface of the second substrate, and the side wall.

A method of forming a piezoelectric thin film can include depositing a material on a first surface of a Si substrate to provide a stress neutral template layer. A piezoelectric thin film including a Group III element and nitrogen can be sputtered onto the stress neutral template layer and a second surface of the Si substrate that is opposite the first surface can be processed to remove that Si substrate and the stress neutral template layer to provide a remaining portion of the piezoelectric thin film. A piezoelectric resonator can be formed on the remaining portion of the piezoelectric thin film.