A composite wafer having an oxide single-crystal film transferred onto a support wafer, the film being a lithium tantalate or lithium niobate film, and the composite wafer being unlikely to have cracking or peeling caused in the lamination interface between the film and the support wafer. More specifically, a method of producing the composite wafer, including steps of: implanting hydrogen atom ions or molecule ions from a surface of the oxide wafer to form an ion-implanted layer inside thereof; subjecting at least one of the surface of the oxide wafer and a surface of the support wafer to surface activation treatment; bonding the surfaces together to obtain a laminate; heat-treating the laminate at 90° C. or higher at which cracking is not caused; and exposing the heat-treated laminate to visible light to split along the ion-implanted layer to obtain the composite wafer.

A method for transferring a piezoelectric layer from a donor substrate onto a support substrate comprises the steps of: a) providing a predetermined splitting area in a piezoelectric donor substrate, b) attaching the piezoelectric donor substrate to a support substrate to form an assembly, and c) detaching the piezoelectric layer from the piezoelectric donor substrate comprising applying an electric field. By using the electric field, the detachment step can be carried out at low temperatures. A detachment chamber for carrying out at least a portion of such a method includes one or two chucks comprising first and/or second electrodes for applying an electric field to a piezoelectric layer.

A piezoelectric element includes a piezoelectric layer, a first electrode layer, and a second electrode layer. The piezoelectric layer includes first and second surfaces opposed to each other. The first electrode layer is located on the first surface. The second electrode layer is located on the second surface. At least a portion of the second electrode layer faces the first electrode layer with the piezoelectric layer interposed therebetween. The second electrode layer mainly includes silicon. The piezoelectric layer is monocrystalline.

A piezoelectric element includes a laminate and a first internal electrode. The laminate includes a pair of main faces, a pair of end faces, and a pair of side faces. The first internal electrode includes four electrode portions and a connector. The four electrode portions include a first pair of electrode portions and a second pair of electrode portions. The connector connects the first pair of electrode portions. The connector is spaced apart from each of the second pair of electrode portions by a first distance. Each of the four electrode portions includes a main electrode part. The main electrode part is spaced apart from the pair of end faces by a second distance. The main electrode part is spaced apart from the pair of side faces by a third distance. The first distance is longer than each of the second distance and the third distance.

A method for manufacturing a film on a support having a non-flat surface comprises: providing a donor substrate having a non-flat surface, forming an embrittlement zone in the donor substrate so as to delimit the film to be transferred, forming the support by deposition on the non-flat surface of the film to be transferred, and detaching the donor substrate along the embrittlement zone, so as to transfer the film onto the support.

Substrate is produced by using a MEMS technique to form multiple diaphragms in a substrate by forming piezoelectric material layer on one surface of the substrate and thereafter by forming openings in the substrate from the other surface of the substrate; substrate and substrate on which signal detection circuit is formed are aligned to each other using at least one of multiple diaphragms as alignment diaphragm; and substrate and substrate are bonded together.

A PZT microactuator such as for a hard disk drive has a restraining layer bonded on its side that is opposite the side on which the PZT is mounted. The restraining layer comprises a stiff and resilient material such as stainless steel. The restraining layer can cover most or all of the top of the PZT, with an electrical connection being made to the PZT where it is not covered by the restraining layer. The restraining layer reduces bending of the PZT as mounted and hence increases effective stroke length, or reverses the sign of the bending which increases the effective stroke length of the PZT even further. The restraining layer can be one or more active layers of PZT material that act in the opposite direction as the main PZT layer. The restraining layer(s) may be thinner than the main PZT layer.

A piezoelectric element includes a piezoelectric layer, a first electrode layer, a second electrode layer, and a coupling electrode. At least a portion of the second electrode layer faces the first electrode layer with the piezoelectric layer interposed therebetween. The second electrode layer includes a coupling area. The coupling area meets a through hole in a region of the second electrode layer not facing the first electrode layer. The coupling electrode is on the coupling area. Between the coupling area and the surface of the second electrode layer on the piezoelectric layer side excluding the coupling area, the difference in position is about 5 nm or less.

A thin-film piezoelectric actuator includes: a substrate; a lower electrode laminated on the substrate; a laminated structure configured to be laminated on the lower electrode and including a plurality of thin-film piezoelectric films alternately laminated with an intermediate electrode between; an upper electrode laminated on the laminated structure; a first protective layer configured to be provided on an upper surface of the upper electrode and made of an alloy material containing iron, cobalt, and molybdenum; and a second protective layer configured to be provided at least on an upper surface of an end portion of the intermediate electrode that is not between the thin-film piezoelectric films, and made of an alloy material containing iron, cobalt, and molybdenum. The present invention provides a thin-film piezoelectric actuator that can achieve high performance and can effectively suppress the occurrence of cracks at the end portion of the piezoelectric film in the lower layer.

A method for manufacturing a hybrid structure comprising an effective layer of piezoelectric material having an effective thickness and disposed on a supporting substrate having a substrate thickness and a thermal expansion coefficient lower than that of the effective layer includes: a) a step of providing a bonded structure comprising a piezoelectric material donor substrate and the supporting substrate, b) a first step of thinning the donor substrate to form a thinned layer having an intermediate thickness and disposed on the supporting substrate, the assembly forming a thinned structure; c) a step of heat treating the thinned structure at an annealing temperature; and d) a second step, after step c), of thinning the thinned layer to form the effective layer. The method also comprises, prior to step b), a step a′) of determining a range of intermediate thicknesses that prevent the thinned structure from being damaged during step c).