A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. Patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the electrodes and a planarized support layer is deposited over the sacrificial layer. The device can include a dielectric protection layer (DPL) that protects the piezoelectric layer from etching processes that can produce rough surfaces and reduces parasitic capacitance around the perimeter of the resonator when the DPL's dielectric constant is lower than that of the piezoelectric layer. The DPL can be configured between the top electrode and the piezoelectric layer, between the bottom electrode and the piezoelectric layer, or both.

A manufacturing method of micro fluid actuator includes: providing a substrate; depositing a first protection layer on a first surface of the substrate; depositing an actuation region on the first protection layer; applying lithography dry etching to a portion of the first protection layer to produce at least one first protection layer flow channel; applying wet etching to a portion of a main structure of the substrate to produce a chamber body and a first polycrystalline silicon flow channel region, while a region of an oxidation layer middle section of the main structure is not etched; applying reactive-ion etching to a portion of a second surface of the substrate to produce at least one substrate silicon flow channel; and applying dry etching to a portion of a silicon dioxide layer to produce at least one silicon dioxide flow channel.

A process for producing a piezoelectric sensor includes the following steps: a step of providing a housing made of stainless steel; a step of producing a solution of a compound comprising a metal or metalloid element; a step of depositing a layer of the solution over at least one inner surface of the housing; a step of oxidizing the deposited layer of solution; a step of placing a piezoelectric element inside the housing; a step of closing the housing. A piezoelectric sensor obtained by means of such a process and comprising a closed steel housing, a piezoelectric element arranged inside the housing and a layer of a solution of a compound comprising a metal or metalloid element that is arranged over at least one inner surface of the housing.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. A first patterned electrode is deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the first electrode and a planarized support layer is deposited over the sacrificial layer, which is then bonded to a substrate wafer. The crystalline substrate is removed and a second patterned electrode is deposited over a second surface of the film. The sacrificial layer is etched to release the air reflection cavity. Also, a cavity can instead be etched into the support layer prior to bonding with the substrate wafer. Alternatively, a reflector structure can be deposited on the first electrode, replacing the cavity.

An example of a cavity structure comprises a cavity substrate comprising a substrate surface, a cavity extending into the cavity substrate, the cavity having a cavity bottom and cavity walls, and a cap disposed on a side of the cavity opposite the cavity bottom. The cavity substrate, the cap, and the one or more cavity walls form a cavity enclosing a volume. A component can be disposed in the cavity and can extend above the substrate surface. The component can be a piezoelectric or a MEMS device. The cap can have a tophat configuration. The cavity structure can be micro-transfer printed from a source wafer to a destination substrate.

Provided is a piezoelectric device and an MEMS device whose size can be reduced. The piezoelectric device includes: a first substrate that includes a first surface on which a piezoelectric element and a first electrode coupled to the piezoelectric element are disposed; a second substrate that includes a second surface on which a second electrode configured to be coupled to a control circuit is disposed; and a third substrate that is disposed between the first substrate and the second substrate, and includes a third surface bonded to the first surface and a fourth surface facing the second surface, in which the third substrate has a through hole passing through from the third surface to the fourth surface, and a third electrode provided in the through hole and coupled to the first electrode, and the second electrode is coupled to the third electrode and is electrically coupled to the first electrode via the third electrode.

A wafer level ultrasonic device includes a composite layer, a first conductive layer, a second conductive layer, a base, a first electrical connection region, and a second electrical connection region. The composite layer includes an ultrasonic element and a protective layer. The ultrasonic element includes a first electrode and a second electrode. The protective layer has a first connecting channel and a second connecting channel respectively corresponding to the first electrode and the second electrode. The first conductive layer and the second conductive layer are respectively in the first connecting channel and the second connecting channel to connect the first electrode and the second electrode. The base includes an opening forming a closed cavity with the protective layer. The first electrical connection region and the second electrical connection region are respectively filled with metal materials to electrically connect the first conductive layer and the second conductive layer.

A sound transducer, in particular, for an ultrasonic sensor, includes a functional group, the functional group including a diaphragm cup and at least one electroacoustic transducer element. The sound transducer also includes a housing. The diaphragm cup includes a vibratory diaphragm and a circumferential wall, and at least one electroacoustic transducer element, the transducer element being configured to stimulate the diaphragm to vibrate and/or to convert vibrations of the diaphragm into electrical signals. The diaphragm cup is formed from a plastic material, the at least one transducer element being integrated into the vibratory diaphragm, in particular without an additional adhesive layer, the transducer element including a piezoceramic element.

An ultrasonic device includes an ultrasonic sensor, a wiring member, and a housing, in which the wiring member has a covered wire that covers a signal line coupled to the ultrasonic sensor via an insulating layer, and a conductive member that is electrically coupled with the covered wire, the housing has a plurality of housing components having conductivity, and covers the ultrasonic sensor with the plurality of housing components, and the conductive member is electrically coupled to and held by the plurality of housing components.

A piezoelectric device includes a container and an AT-cut crystal element. The AT-cut crystal element has at least one side surface intersecting with a Z-axis of the crystallographic axis of the crystal constituted of three surfaces. The first surface is a surface equivalent to a surface formed by rotating the principal surface by 43.5 with an X-axis of the crystal as a rotation axis. The second surface is a surface equivalent to a surface formed by rotating the principal surface by 575 with the X-axis. The third surface is a surface equivalent to a surface formed by rotating the principal surface by 425 with the X-axis. When two corner portions on a side of a second side opposed to the first side of the AT-cut crystal element are viewed in plan view, each of the two corner portions have an approximately right angle.