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.

A wafer scale ultrasonic sensor assembly includes a wafer substrate, an ultrasonic element, first and second protective layers, conductive wires, a transmitting material, an ASIC, a conductive bump, and a soldering portion. The wafer substrate includes a via. The ultrasonic element is exposed to the via. The conductive wires are on the first protective layer and connected to the ultrasonic element. The second protective layer covers the conductive wires, and the second protective layer has an opening corresponding to the ultrasonic element. The transmitting material contacts the ultrasonic element. The ASIC is connected to the wafer substrate, so that the via forms a space between the ASIC and the ultrasonic element. The conductive pillar is in a via defined through the ASIC, the wafer substrate, and the first protective layer, and the conducive pillar is respectively connected to the conductive wires and the soldering portion.

A wafer level ultrasonic chip module includes a substrate, a composite layer, a conducting material, and a base material. The substrate has a through slot that passes through an upper surface of the substrate and a lower surface of the substrate. The composite layer includes an ultrasonic body and a protective layer. A lower surface of the ultrasonic body is exposed from the through slot. The protective layer covers the ultrasonic body and a partial upper surface of the substrate. The protective layer has an opening, from which a partial upper surface of the ultrasonic body is exposed. The conducting material is in contact with the upper surface of the ultrasonic body. The base material covers the through slot, such that a space is formed among the through slot, the lower surface of the ultrasonic body and an upper surface of the base material.

A MEMS device may include a first electrode region; a first piezoelectric layer arranged over the first electrode region; a second electrode region arranged over the first piezoelectric layer; a second piezoelectric layer arranged over the first piezoelectric layer and the second electrode region; a third electrode region arranged over the second piezoelectric layer; a first input port coupled to the first electrode region and/or the second electrode region for providing a first electrical signal to the first piezoelectric layer to generate a first vibration in the first piezoelectric layer; a second input port coupled to the second electrode region and/or the third electrode region for providing a second electrical signal to the second piezoelectric layer to generate a second vibration in the second piezoelectric layer; and an output port configured to receive an output signal including a superposition of the first vibration and the second vibration.