Provided is an aluminum nitride film in which, aluminum nitride crystal grains containing a metal element differing from aluminum and substituting for aluminum are main crystal grains of a polycrystalline film formed of crystal grains, and a concentration of the metal element in a grain boundary between the aluminum nitride crystal grains in at least one region of first and second regions corresponding to both end portions of the polycrystalline film in a film thickness direction of the polycrystalline film is higher than a concentration of the metal element in a center region of the aluminum nitride crystal grain in the at least one region, and is higher than a concentration of the metal element in a grain boundary between the aluminum nitride crystal grains in a third region located between the first region and the second region in the film thickness direction of the polycrystalline film.

A semiconductor device is provided. The semiconductor device incudes: a first sub-semiconductor structure including a dielectric layer; and a second sub-semiconductor structure, at least including a carrier substrate, and being bonded to the first sub-semiconductor structure. The first sub-semiconductor structure or the second sub-semiconductor structure includes a charge accumulation preventing layer, and the charge accumulation preventing layer is disposed between the carrier substrate and the dielectric layer, and is configured to avoid an undesired conductive channel from being generated due to charge accumulation on a surface of the carrier substrate.

The invention provides a planarization method, which can make the local flatness of the product to be processed more uniform. The product has a cavity filled with oxide and includes a first electrode layer, a piezoelectric layer and a second electrode layer superposed on the cavity. The first electrode layer covers the cavity and includes a first inclined face around the first electrode layer, and the piezoelectric layer covers the first electrode layer and is arranged on the first electrode layer. The planarization method includes: depositing a passivation layer on the second electrode layer and etching the passivation layer completely until the thickness of the passivation layer is reduced to the required thickness.

A fabrication method of a bulk acoustic wave (BAW) resonator includes: sequentially forming a buffer layer, a piezoelectric layer, and a first electrode on a temporary substrate; forming a first dielectric layer on the piezoelectric layer and covering the first electrode; forming a trench in the first dielectric layer; forming a second dielectric layer on the first dielectric layer and in the trench; forming a third dielectric layer on the second dielectric layer and filling in the trench; forming a bonding layer on the third dielectric layer; bonding a resonator substrate to the third dielectric layer via the bonding layer; removing the temporary substrate and the buffer layer to expose a surface layer of the piezoelectric layer; removing the surface layer of the piezoelectric layer; forming a second electrode on the piezoelectric layer; and removing a portion of the first dielectric layer surrounded by the trench to form a cavity.

A bulk acoustic wave resonator includes: a substrate; a membrane layer forming a cavity together with the substrate; a lower electrode disposed on the membrane layer; a piezoelectric layer disposed on a flat surface of the lower electrode; and an upper electrode covering a portion of the piezoelectric layer and exposing a side of the piezoelectric layer to air, wherein the piezoelectric layer includes a step portion extended from the side of the piezoelectric layer and disposed on the flat surface of the lower electrode.

A thin-film bulk acoustic resonator (FBAR) apparatus includes a lower dielectric layer including a first cavity; an upper dielectric layer including a second cavity, wherein the upper dielectric layer is on the lower dielectric layer; and an acoustic resonance film that is positioned between and separating the first and the second cavities. The acoustic resonance film includes a lower electrode layer, an upper electrode layer, and a piezoelectric film that is sandwiched between the lower and upper electrode layers. A plan view of the first and the second cavities overlap to form an overlapped region having a polygonal shape without parallel sides.

A method for producing an adjustable bulk acoustic wave resonator comprising a transducer stack (E1) and a tuning stack (E2). According to the invention, transducer stack (E1) includes two defined electrodes (4, 6) and piezoelectric material (2), and stack (E2) includes a layer of piezoelectric material (8) and two defined electrodes (10, 12). The method includes: a) production of the transducer stack; b) formation of an electrically insulating layer on an electrode (6) of the transducer stack; c) formation of a defined electrode (10) of the tuning stack on the electrically insulting layer such that it is aligned with the electrodes of the transducer stack; d) assembly, on the electrode (10), of a substrate of piezoelectric material; e) fracturing of the substrate of piezoelectric material; and f) formation of the other defined electrode (12) of the tuning stack, aligned with the defined electrode (10).

A bulk acoustic wave filter comprises a substrate, an insulating layer disposed on the substrate and having a first cavity and a second cavity formed therein, a first bulk-acoustic-wave-resonance-structure disposed on the first cavity and a second bulk-acoustic-wave-resonance-structure disposed on the second cavity. The first bulk-acoustic-wave-resonance-structure comprises a first bottom electrode disposed on the first cavity, a first top electrode disposed on the first bottom electrode, a first piezoelectric layer portion sandwiched between the first top electrode and the first bottom electrode, and a first frequency tuning structure disposed between the first cavity and the first bottom electrode. The second bulk-acoustic-wave-resonance-structure comprises a second bottom electrode disposed on the second cavity, a second top electrode disposed on the second bottom electrode, a second piezoelectric layer portion sandwiched between the second top electrode and the second bottom electrode.

An RF filter system including a plurality of BAW resonators arranged in a circuit, the circuit including a serial configuration of resonators and a parallel shunt configuration of resonators, the circuit having a circuit response corresponding to the serial configuration and the parallel configuration of the plurality of bulk acoustic wave resonators including a transmission loss from a pass band having a bandwidth from 5.490 GHz to 5.835 GHz. Resonators include a support member with a multilayer reflector structure; a first electrode including tungsten; a piezoelectric film including aluminum scandium nitride; a second electrode including tungsten; and a passivation layer including silicon nitride. At least one resonator includes at least a portion of the first electrode located within a cavity region defined by a surface of the support member.

An acoustic resonator includes a substrate, an insulation layer disposed on the substrate, a resonating portion disposed on the insulation layer and having a first electrode, a piezoelectric layer, and a second electrode, stacked thereon, a cavity disposed between the insulation layer and the resonating portion, a protruded portion having a plurality of protrusions disposed on a lower surface of the cavity, and a hydrophobic layer disposed on an upper surface of the cavity and a surface of the protruded portion.