A composite substrate capable of improving temperature characteristics while suppressing crack generation and a method for manufacturing such composite substrate is provided. The method for manufacturing composite substrates includes: a step of preparing a piezoelectric material substrate having a rough surface; a step of removing the damaged layer by etching the rough surface of the piezoelectric material substrate using a chemical process; a step of depositing an intervening layer on the rough surface of the piezoelectric material substrate from which the damaged layer has been removed; a step of flattening the surface of the deposited intervening layer; a step of bonding the piezoelectric material substrate to a support substrate having a lower thermal expansion coefficient than the piezoelectric material, with the deposited intervening layer in between; and a step of thinning the piezoelectric material substrate after bonding. Lithium tantalate (LT) or lithium niobate (LN) are suitable as the piezoelectric material.

A piezoelectric device includes a first substrate including a first surface on which piezoelectric elements and a common terminal coupled to the piezoelectric elements are placed, a second substrate including a second surface on which a common connecting terminal coupled to a control circuit is placed, a third substrate placed between the first substrate and the second substrate and including a third surface joined to the first surface and a fourth surface facing the second surface, and bonding portions bonding the second substrate and the third substrate by an adhesive, wherein the third substrate includes a first through hole penetrating from the third surface to the fourth surface and a first through electrode provided in the first through hole and coupled to the common terminal, the common connecting terminal is coupled to the first through electrode and electrically coupled to the common terminal via the first through electrode, and the second substrate includes a wall suppressing an outflow of the adhesive on the second surface facing the third substrate.

A piezoelectric micromachined ultrasound transducer (PMUT) device may include a plurality of layers including a structural layer, a piezoelectric layer, and electrode layers located on opposite sides of the piezoelectric layer. Conductive barrier layers may be located between the piezoelectric layer and the electrodes to the prevent diffusion of the piezoelectric layer into the electrode layers.

A method of manufacturing a disk drive suspension includes applying an adhesive to an actuator mounting portion, increasing viscosity of the adhesive by emitting light to the adhesive applied to the actuator mounting portion, arranging the piezoelectric element on the adhesive having the increased viscosity, detecting a height of the piezoelectric element arranged on the actuator mounting portion, and correcting an irradiation condition of the light in accordance with the detected height of the piezoelectric element.

A method for manufacturing a film, notably monocrystalline, on a flexible sheet, comprises the following steps: providing a donor substrate, forming an embrittlement zone in the donor substrate so as to delimit the film, forming the flexible sheet by deposition over the surface of the film, and detaching the donor substrate along the embrittlement zone so as to transfer the film onto the flexible sheet.

A piezoelectric device includes a membrane portion including a through slot extending through the membrane portion in an up-down direction. A width of the through slot in a single crystal piezoelectric material layer becomes narrower as the through slot extends downward. In the single crystal piezoelectric material layer and a reinforcing layer, a maximum width of the through slot in a layer located on a bottom side is smaller than a minimum width of the through slot in a layer located on a top side.

A glass membrane deformation assembly configured to deform a glass membrane includes: a deformable glass membrane having a first surface and a second surface; a piezoelectric layer affixed to at least a portion of the first surface of the deformable glass membrane, wherein the piezoelectric layer is controllably deformable via a voltage potential; and a structural layer affixed to at least a portion of the second surface of the deformable glass membrane; wherein the controllably deformation of the piezoelectric layer is configured to controllably deform the deformable glass membrane.

A piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K.sub.1-xNa.sub.x)NbO.sub.3 (0<x<1), wherein an average light transmittance through the piezoelectric film in a wavelength region of visible light and near-infrared ray is 65% or more.

Provided are a composite substrate in which a wafer to be bonded has a sufficiently small surface roughness and which can be prevented from causing film peeling, and a method for producing the composite substrate. The composite substrate 40 of the present invention has a silicon wafer 10, an interlayer 11, and a single-crystal silicon thin film or oxide single-crystal thin film 20a stacked in the order listed and has a damaged layer 12a in a portion of the silicon wafer 10 on the side of the interlayer 11.

An acoustic wave device includes a support substrate, a piezoelectric layer provided on the support substrate, at least a pair of comb-shaped electrodes provided on the piezoelectric layer, each of the comb-shaped electrodes including a plurality of electrode fingers, and an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer having, in at least a part thereof, a plurality of void regions of which extending directions are different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the void regions being longer than a width in a direction orthogonal to the corresponding extending direction when viewed from the thickness direction of the support substrate.