Methods for forming a film bulk acoustic resonator (FBAR) are provided. In the method, formation of several mutually overlapped and hence connected sacrificial material layers above and under a resonator sheet facilitates the removal of the sacrificial material layers. Cavities left after the removal overlap at a polygonal area with non-parallel sides. This reduces the likelihood of boundary reflections of transverse parasitic waves causing standing wave resonance in the FBAR, thereby enhancing its performance in parasitic wave crosstalk. Further, according to the disclosure, the FBAR is enabled to be integrated with CMOS circuitry and hence exhibits higher reliability.

An elastomer piezoelectric element is configured by alternately disposing first opposite electrodes and second opposite electrodes, and sandwiching a dielectric layer between each first opposite electrode and the corresponding second opposite electrode. Each of the dielectric layers includes a dielectric elastomer sheet-shaped dielectric portion and a conductive elastomer first common electrode connecting the first opposite electrodes to each other or a conductive elastomer second common electrode connecting the second opposite electrodes to each other. The first common electrode and the second common electrode are provided so as to extend from one main surface to another main surface of the dielectric portion, and are joined to the first opposite electrode and the second opposite electrode, respectively, on a joint surface along the dielectric layer.

A substrate includes a substrate main body that includes a first main surface and a second main surface facing the first main surface. First electrode lands are disposed inside a recessed portion of the first main surface of the substrate main body. Second electrode lands are disposed in a region outside the recessed portion. The first electrode land and the second electrode land are connected to different electric potentials.

A multilayer piezoelectric ceramic is constituted by: piezoelectric ceramic layers which do not contain lead as a constituent element, have a perovskite compound expressed by the composition formula Li.sub.xNa.sub.yK.sub.1xyNbO.sub.3 (where 0.02<x0.1, 0.02<x+y1) as the primary component, and contain 0.2 to 3.0 mol of Li relative to 100 mol of the primary component; and internal electrode layers which are constituted by a metal that contains silver by 80 percent by mass or more; wherein the multilayer piezoelectric ceramic is such that Li compounds other than the primary component are localized therein. The multilayer piezoelectric element can offer excellent insulating property.

A film bulk acoustic resonator (FBAR) and a method of fabricating the FBAR are disclosed. In the method, formation of several mutually overlapped and hence connected sacrificial material layers above and under a resonator sheet facilitates the removal of the sacrificial material layers. Cavities left after the removal overlap at a polygonal area with non-parallel sides. This reduces the likelihood of boundary reflections of transverse parasitic waves causing standing wave resonance in the FBAR, thereby enhancing its performance in parasitic wave crosstalk. Further, according to the invention, the FBAR is enabled to be integrated with CMOS circuitry and hence exhibits higher reliability.

An elastomer piezoelectric element includes a plurality of unit layers disposed along a thickness direction of the elastomer piezoelectric element. Each of the unit layers includes a sheet-shaped dielectric elastomer dielectric portion, a conductive elastomer electrode partially disposed on a first surface of the dielectric portion, and an insulating elastomer insulated portion that is provided in at least a portion of an area surrounding the electrode and brings a thickness of the unit layer in a portion in which the electrode is not disposed close to a thickness of the unit layer in a portion in which the electrode is disposed.

The piezoelectric element includes a piezoelectric composite including a plurality of piezoelectrics and a reaction product, and an electrode pair. The plurality of piezoelectrics is disposed in alignment at an interval of 1 to 10 m. The aspect ratio of each of the piezoelectrics is 5 or higher. The reaction product is a reaction product of a crosslinkable epoxy resin composition containing an elastomer component, a crosslinkable epoxy resin, and a crosslinking agent. One or each of a number of epoxy groups per molecule of the crosslinkable epoxy resin and a crosslinking value of the crosslinking agent is 3 or more.

A method of fabricating pre-structured functional wafers, pre-structured functional cuboid or wafer stack, and a method of fabricating an array of functional multilayer stack actuators made of relaxor ferroelectric single crystal piezoelectric thin layers comprising sequentially repeated steps of wafer dicing and trench refilling into relatively thick wafer(s). A bulk-micromachined dimensioned deformable mirror device comprising a base supporting substrate, a plurality of stack actuators that is made by segmenting a pre-structured relaxor ferroelectric single crystal piezoelectric cuboid or wafer stack, a plurality of pedestals disposed on the plurality of stack actuators; a deformable membrane mirror mounted on said pedestals; and a plurality of addressable electrode contacts.

In a method of manufacturing a piezoelectric device, during an isolation formation step, a supporting substrate has a piezoelectric thin film formed on its front with a compressive stress film present on its back. The compressive stress film compresses the surface on a piezoelectric single crystal substrate side of the supporting substrate, and the piezoelectric thin film compresses the back of the supporting substrate, which is opposite to the surface on the piezoelectric single crystal substrate side. Thus, the compressive stress produced by the compressive stress film and that produced by the piezoelectric thin film are balanced in the supporting substrate, which causes the supporting substrate to be free of warpage and remain flat. A driving force that induces isolation in the isolation formation step is gasification of the implanted ionized element rather than the compressive stress to the isolation plane produced by the piezoelectric thin film.

A piezoelectric micromachined ultrasonic transducer (PMUT) device includes a substrate having an opening therethrough and a membrane attached to the substrate over the opening. An actuating structure layer on a surface of the membrane includes a piezoelectric layer sandwiched between the membrane and an upper electrode layer. The actuating structure layer is patterned to selectively remove portions of the actuating structure from portions of the membrane to form a central portion proximate a center of the open cavity and three or more rib portions projecting radially outward from the central portion.