A nano-mechanical acoustical resonator is designed and fabricated with CMOS compatible techniques to apply to mm-wave RF front-ends and 5G wireless communication systems which have extreme small scale and integrated in 3D sensors and actuators. Thin hafnium zirconium oxide (HZO) films are engineered with atomic layer deposition (ALD) to demonstrate large piezoelectric ferroelectric properties (piezoelectric coefficient e.sub.31,HZO23e.sub.31,AlN. Various electrical and optical characterization schemes are also used as test-vehicles to characterize ferroelectric and piezoelectric properties, including isolated 10 nm HZO- and 120 nm AlN-transduction ports. The low-temperature and truly conformal nature of ALD process of HZO offers substantial advantages over conventional magnetronsputtered/MOCVD films, including CMOS-compatibility and sidewall transducer integration.

Techniques are disclosed for forming high frequency film bulk acoustic resonator (FBAR) devices that include a bottom electrode formed of a two-dimensional electron gas (2DEG). The disclosed FBAR devices may be implemented with various group III-nitride (III-N) materials, and in some cases, the 2DEG may be formed at a heterojunction of two epitaxial layers each formed of III-N materials, such as a gallium nitride (GaN) layer and an aluminum nitride (AlN) layer. The 2DEG bottom electrode may be able to achieve similar or increased carrier transport as compared to an FBAR device having a bottom electrode formed of metal. Additionally, in some embodiments where AlN is used as the piezoelectric material for the FBAR device, the AlN may be epitaxially grown which may provide increased performance as compared to piezoelectric material that is deposited by traditional sputtering techniques.

This method for manufacturing a lead-free niobate-system ferroelectric thin film device includes: a lower electrode film formation step of forming a lower electrode film on a substrate; a ferroelectric thin film formation step of forming a niobate-system ferroelectric thin film on the lower electrode film; an etch mask pattern formation step of forming an etch mask in a desired pattern on the niobate-system ferroelectric thin film; and a ferroelectric thin film etching step of shaping the niobate-system ferroelectric thin film into a desired fine pattern by wet etching using an etchant comprising: a predetermined chelating agent including at least one selected from EDTMP, NTMP, CyDTA, HEDP, GBMP, DTPMP, and citric acid; an aqueous alkaline solution containing an aqueous ammonia solution; and an aqueous hydrogen peroxide solution.

A method of generating a piezoelectric actuator includes: forming a piezoelectric member upon a rigid substrate; and removing one or more portions of the rigid substrate to form one or more gaps in the rigid substrate, thus defining at least one deformable portion of the piezoelectric member and at least one rigid portion of the piezoelectric member

A method of forming a piezoelectric thin film includes sputtering a first surface of a substrate to provide a piezoelectric thin film comprising AlN, AlScN, AlCrN, HfMgAlN, or ZrMgAlN thereon, processing a second surface of the substrate that is opposite the first surface of the substrate to provide an exposed surface of the piezoelectric thin film from beneath the second surface of the substrate, wherein the exposed surface of the piezoelectric thin film includes a first crystalline quality portion, removing a portion of the exposed surface of the piezoelectric thin film to access a second crystalline quality portion that is covered by the first crystalline quality portion, wherein the second crystalline quality portion has a higher quality than the first crystalline quality portion and processing the second crystalline quality portion to provide an acoustic resonator device on the second crystalline quality portion.

A method of manufacture and structure for an acoustic resonator device having a hybrid piezoelectric stack with a strained single crystal layer and a thermally-treated polycrystalline layer. The method can include forming a strained single crystal piezoelectric layer overlying the nucleation layer and having a strain condition and piezoelectric layer parameters, wherein the strain condition is modulated by nucleation growth parameters and piezoelectric layer parameters to improve one or more piezoelectric properties of the strained single crystal piezoelectric layer. Further, the method can include forming a polycrystalline piezoelectric layer overlying the strained single crystal piezoelectric layer, and performing a thermal treatment on the polycrystalline piezoelectric layer to form a recrystallized polycrystalline piezoelectric layer. The resulting device with this hybrid piezoelectric stack exhibits improved electromechanical coupling and wide bandwidth performance.

A method of forming a piezoelectric film can include providing a wafer in a CVD reaction chamber and forming an aluminum nitride material on the wafer, the aluminum nitride material doped with a first element E1 selected from group IIA or from group IIB and doped with a second element E2 selected from group IVB to provide the aluminum nitride material comprising a crystallinity of less than about 1.5 degree at Full Width Half Maximum (FWHM) to about 10 arcseconds at FWHM measured using X-ray diffraction (XRD).

A thin-film piezoelectric-material element includes a laminated structure part having a lower electrode film, a piezoelectric-material film laminated on the lower electrode film and an upper electrode film laminated on the piezoelectric-material film, a lower piezoelectric-material protective-film being formed with alloy material, and an upper piezoelectric-material protective-film being formed with alloy material. The lower piezoelectric-material protective-film and the upper piezoelectric-material protective-film are formed respectively in the lower side of the lower electrode film and the upper side of the upper electrode film, of the laminated structure part, so as to sandwich the laminated structure part. The lower piezoelectric-material protective-film, and the upper piezoelectric-material protective-film are formed with alloy material including Fe as main ingredient and having Co and Mo, by Ion beam deposition.

A piezoelectric thin film composed of aluminum nitride and which contains magnesium and 31 to 120 atomic percent of niobium relative to 100 atomic percent of the magnesium, and the total content of the magnesium and the niobium relative to the total sum of contents of the magnesium, the niobium and the aluminum nitride falls within the range of 10 to 67 atomic percent.

A thin-film piezoelectric-material element includes a laminated structure part having a lower electrode film, a piezoelectric-material film laminated on the lower electrode film and an upper electrode film laminated on the piezoelectric-material film, a lower piezoelectric-material protective-film being formed with alloy material, and an upper piezoelectric-material protective-film being formed with alloy material. The lower piezoelectric-material protective-film and the upper piezoelectric-material protective-film are formed respectively in the lower side of the lower electrode film and the upper side of the upper electrode film, of the laminated structure part, so as to sandwich the laminated structure part.