The invention relates to a method for producing ceramics having piezoelectric properties in predominantly aqueous suspending agents.

A production method for a surface acoustic wave device comprises the following steps: a step of providing a piezoelectric substrate comprising a transducer arranged on the main front face; a step of depositing a dielectric encapsulation layer on the main front face of the piezoelectric substrate and on the transducer; and a step of assembling the dielectric encapsulation layer with the main front face of a support substrate having a coefficient of thermal expansion less than that of the piezoelectric substrate. In additional embodiments, a surface acoustic wave device comprises a layer of piezoelectric material equipped with a transducer on a main front face, arranged on a substrate support of which the coefficient of thermal expansion is less than that of the piezoelectric material. The transducer is arranged in a dielectric encapsulation layer, between the layer of piezoelectric material and the support substrate.

A method of producing a composite substrate includes: forming a first layer on a lower surface side of a piezoelectric substrate having an upper surface and a lower surface facing each other and having an electrode formed on the lower surface; performing flattening treatment to set a waviness of a surface of the first layer to more than 2 nm and 70 nm or less; and joining a support substrate to a first layer side of the piezoelectric substrate having the first layer formed thereon.

A method of producing a composite substrate includes: forming a first layer on a lower surface side of a piezoelectric substrate having an upper surface and a lower surface facing each other and having an electrode formed on the lower surface; performing flattening treatment to set a waviness of a surface of the first layer to more than 2 nm and 70 nm or less; and joining a support substrate to a first layer side of the piezoelectric substrate having the first layer formed thereon.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.

A composite substrate of the present disclosure includes a piezoelectric substrate having a first surface which is an element formation surface and a second surface which is a back surface of the first surface, a sapphire substrate having a third surface which is disposed opposing a second surface and a fourth surface which is a back surface of the third surface, a fifth surface opposing the second surface, and a sixth surface opposing the third surface. It includes an alumina layer bonding the second surface and the third surface, and an arithmetic mean roughness Ra of the third surface is 0.1 ?m or more and 0.5 ?m or less. The arithmetic mean roughness Ra of the fifth surface is 0.1 ?m or less and is smaller than the arithmetic mean roughness Ra of the third surface.

To improve the Q value of a piezoelectric thin-film element in a state in which unnecessary vibration is suppressed, an acoustic reflection film (104) is affixed to a first electrode (102), a piezoelectric single-crystal substrate (101) is thinned by polishing from the other surface (101b) of the piezoelectric single-crystal substrate (101), such that the first electrode (102) and piezoelectric thin film (105) are piled on the piezoelectric single-crystal substrate (101). In this polishing, a pressure (polishing pressure) to the surface (101b) during polishing in an electrode formation region where the first electrode (102) is formed differs from that in a non-electrode formation region around the electrode formation region. Consequently, the electrode formation region of the piezoelectric thin film (105), where the first electrode (102) is formed, is made thinner than the non-electrode formation region around the electrode formation region.

A tape cast transducer element assembly comprises a tape cast transducer element including a multi-layer piezoelectric stack diced from a sintered piezoelectric body formed from a plurality of thin film tape layers, the film thin tape layers sintered to produce a final density. A conductive film coats select ones of the thin film tape layers such that conductive layers of different polarities are exposed on opposing sides of the multi-layer piezoelectric stack. Electrodes are coupled to the conductive layers. Electrical leads are coupled to each electrode. A head mass is configured to encapsulate a top portion of the stack. A tail mass is configured to encapsulate a bottom portion of the stack. At least one coupling arrangement extends from a top surface of the head mass through the cross-sectional area of the head mass into the tail mass such that the stack is contained in a rigid assembly under compression.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.