An acoustic wave device includes a substrate, lower and upper electrodes provided over the substrate, a piezoelectric film that is provided over the substrate, is interposed between the lower and upper electrodes, and has a pair of through holes that sandwich a resonance region therebetween in a first direction, are provided along the resonance region, and are connected to an air gap that is formed between the substrate and the lower electrode and overlaps the resonance region in the plan view, the lower and upper electrodes overlapping across the piezoelectric film in the resonance region, and additional films that are not provided in a central region of the resonance region in the plan view and are provided in respective edge regions, which are located on respective sides of the central region in a second direction substantially orthogonal to the first direction in the plan view, of the resonance region.

This disclosure relates generally to a method of making a piezoelectric device. In some embodiments, a foundation structure is provided and a first metal is deposited over at least a first area of a top surface of the foundation structure to form a plurality of metal islands such that the plurality of metal islands self-assemble in a distributed manner over the at least the first area of the top surface of the foundation structure. Additionally, a piezoelectric material is deposited over the at least the first area of the top surface of the foundation structure to form a piezoelectric film over the at least the first area of the top surface of the foundation structure. The piezoelectric material is deposited over the first area of the top surface of the foundation structure to form the piezoelectric film and the piezoelectric film is polarity patterned into at least one non-piezoelectric portion.

An acoustic resonator device includes a substrate having a surface; an 82Y-cut lithium niobate piezoelectric plate attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm that spans a cavity in an intermediate dielectric layer of the substrate; an interdigital transducer (IDT) at the piezoelectric plate such that interleaved fingers of the IDT are at the diaphragm; and a plurality of stripes of a dielectric material extending over ends of the interleaved fingers and portions of gaps between the ends of the interleaved fingers and opposing busbars of the IDT.

A method for fabricating a multi-layer resonator assembly includes sequentially fabricating a plurality of vertically-stacked resonator layers including, for each resonator layer of the plurality of resonator layers, depositing a dielectric layer, forming at least one film bulk acoustic resonator (FBAR) cavity in the deposited dielectric layer, filling each FBAR cavity of the at least one FBAR cavity with a sacrificial material block, and depositing a FBAR material stack over the at least one FBAR cavity. The deposited FBAR material stack is in contact with the sacrificial material block and the dielectric layer. The method further includes removing the sacrificial material block from the at least one FBAR cavity for each resonator layer of the plurality of resonator layers subsequent to sequentially fabricating the plurality of resonator layers.

A film bulk acoustic wave resonator comprising a piezoelectric film having a central region defining a main active domain in which a main acoustic wave is generated during operation, an upper electrode disposed on a top surface of the piezoelectric film, a lower electrode disposed on a lower surface of the piezoelectric film, a dielectric material layer disposed on a lower surface of the lower electrode, and lower recessed frame regions disposed laterally on opposite sides of the central region, the lower recessed frame regions defined by regions of one of the dielectric material or of the lower electrode having a lesser thickness than the thickness of the one of the dielectric material layer or of the lower electrode in the central region.

A BAW resonator includes: a piezoelectric film array, including multiple piezoelectric films between a substrate of a chip and a capping layer on the top, where multiple first cavities are provided between adjacent piezoelectric films in a vertical direction, between the piezoelectric films and the capping layer, and between the piezoelectric films and the substrate, second cavities are shared between adjacent piezoelectric films in a first direction in a horizontal plane, and third cavities are shared between adjacent piezoelectric films in a second direction in the horizontal plane; multiple electrode layers, covering at least the top surface and bottom surface of each of the piezoelectric films; and multiple electrode interconnection layers, connected to the electrode layers on the bottom surfaces of the piezoelectric films along sidewalls of the third cavities.

An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

An acoustic resonator forms a component of an FBAR filter that includes a trap-rich layer to avoid parasitic conduction by degrading carrier lifetimes of a free charge carriers. The acoustic resonator has a first electrode, a second electrode disposed parallel to the first planar portion and a piezoelectric layer disposed between and contacting both the first and second planar electrodes. A silicon-based a support layer is bonded to the second electrode and includes a trap region. The acoustic resonator may be manufactured by (a) depositing the trap region on the support layer; (b) oxidizing a surface of the trap region; (c) depositing a bonding layer on the oxidized surface of the trap region; (d) bonding a first electrode to the bonding layer; (e) contacting a first side of a piezoelectric layer to the electrode; and (f) contacting a second side of the piezoelectric layer a second electrode.

Filter devices are disclosed. A filter device includes a piezoelectric plate comprising a supported portion, a first diaphragm, and a second diaphragm. The supported portion is attached to a substrate and the first and second diaphragms spans respective cavities in the substrate. A first interdigital transducer (IDT) has interleaved fingers on the first diaphragm. A second interdigital transducer (IDT) has interleaved fingers on the second diaphragm. A first dielectric layer is between the interleaved fingers of the first IDT, and a second dielectric layer is between the interleaved fingers of the second IDT. A thickness of the first dielectric layer is greater than a thickness of the second dielectric layer. The piezoelectric plate and the first and second IDTs are configured such that radio frequency signals applied to first and second IDTs excite primary shear acoustic modes in the respective diaphragms.

A piezoelectric element includes a second electrode layer on a second surface of a single-crystal piezoelectric layer. A hole continuous with a through-hole is provided in the second electrode layer. The second electrode layer is made of Pt, Ti, Al, Cu, Au, Ag, Mg, or an alloy including at least one of the metals as a main ingredient. A third electrode layer is on one side of the second electrode layer opposite to the single-crystal piezoelectric layer. The third electrode layer includes at least a portion outside of an edge of the hole with a distance maintained relative to the edge of the hole when viewed in a direction perpendicular or substantially perpendicular to the second surface. The third electrode layer is made of Ni or an alloy including Ni as a main ingredient.