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. One or more patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the one or more electrodes and a planarized support layer is deposited over the sacrificial layer. The support layer is etched to form one or more cavities overlying the electrodes to expose the sacrificial layer. The sacrificial layer is etched to release the cavities around the electrodes. Then, a cap layer is fusion bonded to the support layer to enclose the electrodes in the support layer cavities.

Embodiments disclosed herein include potassium sodium niobate (KNN) films and methods of making such films. In an embodiment, a method of forming a potassium sodium niobate (KNN) film comprises preparing a solution comprising water, potassium hexaniobate salts, and sodium hexaniobate salts. In an embodiment, the solution is spin coated onto a substrate to form a film on at least a portion of a surface of the substrate. In an embodiment, the method may further comprise heat treating the film.

A copolymer including units derived from fluoro monomers of formula (I):

CX.sub.1X.sub.2═CX.sub.3X.sub.4  (I) in which each of the X.sub.1, X.sub.2, X.sub.3 and X.sub.4 is independently chosen from H, F and alkyl groups including from 1 to 3 carbon atoms which are optionally partially or totally fluorinated, the H and/or F atoms of the fluoro monomers being partially replaced with photoactive groups of formula —Y—Ar—R in the copolymer; Y representing an oxygen atom or an NH group or a sulfur atom, Ar representing an aryl group, preferably a phenyl group, and R being a monodentate or bidentate group including from 1 to 30 carbon atoms. The fluoro monomers of formula (I) of the copolymer include vinylidene fluoride and trifluoroethylene. Also, a process for preparing this copolymer, a composition including this copolymer, and a film obtained from the copolymer.

A copolymer including fluorinated units of formula (I):

—CX.sub.1X.sub.2—CX.sub.3X.sub.4—  (I) in which each of the X.sub.1, X.sub.2, X.sub.3 and X.sub.4 is independently chosen from H, F and alkyl groups including from 1 to 3 carbon atoms which are optionally partially or totally fluorinated; and units of formula (III):

—CX.sub.AX.sub.B—CX.sub.CZ—  (III) in which each of the X.sub.A, X.sub.B and X.sub.C is independently chosen from H, F and alkyl groups including from 1 to 3 carbon atoms which are optionally partially or totally fluorinated, and Z being a polarizable group of formula —Y—Ar—R; Y representing an O atom or an S atom or an NH group, Ar representing an aryl group, and R being a monodentate or bidentate group including from 1 to 30 carbon atoms; and the copolymer having a heat of fusion of greater than or equal to 5 J/g. Also a process, a composition, an ink and a film.

A piezoelectric device includes a piezoelectric body, a vibration plate that vibrates when the piezoelectric body is driven, a first electrode positioned between the piezoelectric body and the vibration plate, and a second electrode positioned to be separated from the first electrode by the piezoelectric body. The piezoelectric body has an active portion that is a part sandwiched between the first electrode and the second electrode in a first direction along a thickness direction of the piezoelectric body, and a change width of a dC/dV value, which represents a change in capacitance with respect to a change in a voltage applied along a second direction orthogonal to the first direction, from one end of the active portion on a side of the first electrode to the other end of the active portion on a side of the second electrode in the first direction is 10% or less.

A method for polarizing a piezoelectric film is described. In this method, a piezoelectric film is formed by using an injection deposition method. The piezoelectric film is flat adhered to a surface of a conductive substrate. A polarization process is performed on the piezoelectric film while the piezoelectric film is flat adhered to the surface of the conductive substrate.

A metal strip and a coil coating process for multilayer coating of an endless metal strip are disclosed in which a curable polymer primer is applied to a flat side of the metal strip with the aid of a roller application in order to form an electrically insulating primer layer, a curable polymer varnish is applied to this primer layer with the aid of a roller application and cured in order to form an electrically insulating varnish layer, and at least one electric conductor layer is printed at least in some areas between the primer layer and the varnish layer. In order to enable a stable and inexpensive electrical functionalization of a metal strip, it is proposed that an electrically polarizable layer be applied to at least some regions of the electric conductor layer and that the electric conductor layer and electrically polarizable layer be applied by means of a wet-on-wet process.

Embodiments disclosed herein include potassium sodium niobate (KNN) films and methods of making such films. In an embodiment, a method of forming a potassium sodium niobate (KNN) film comprises preparing a solution comprising water, potassium hexaniobate salts, and sodium hexaniobate salts. In an embodiment, the solution is spin coated onto a substrate to form a film on at least a portion of a surface of the substrate. In an embodiment, the method may further comprise heat treating the film.

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.

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.