An acoustic resonator device includes a piezoelectric plate attached to a substrate. A portion of the piezoelectric plate forms a diaphragm suspended over a cavity in the substrate. A first conductor level includes first and second interdigital transducer (IDT) first-level busbars disposed along opposing sides of the diaphragm, and first and second sets of IDT fingers extending from the first and second busbars, respectively, wherein the first and second sets of IDT fingers are interleaved and disposed on the diaphragm. A second conductor level includes first and second second-level busbars that overlap at least a portion of the first and second busbars, respectively.

Acoustic resonator devices and methods are disclosed. An acoustic resonator device includes a piezoelectric plate having opposed front and back surfaces. A first electrode and a second electrode are formed on the front surface of the piezoelectric plate, the first and second electrodes and the piezoelectric plate configured such that a radio frequency signal applied between the first and second electrodes excites a shear primary acoustic mode in the piezoelectric plate. The first electrode and the second electrode have trapezoidal cross-sectional shapes. A sidewall angle of at least one side surface of the first electrode and a sidewall angle of at least one side surface of the second electrode are greater than or equal to 70 degrees and less than or equal to 110 degrees.

Disclosed is a film bulk acoustic resonator (FBAR) type filter including a substrate including two or more cavities on a top surface thereof, a lower electrode formed above the substrate, a piezoelectric layer formed above the lower electrode, two or more upper electrodes formed above the piezoelectric layer, and a package layer including a wall vertically extending while surrounding a periphery of certain areas in which the cavities and the lower electrode are formed and a roof disposed above the wall while being spaced apart from the upper electrodes to seal the certain areas.

An RF integrated circuit device can includes a substrate and a High Electron Mobility Transistor (HEMT) device on the substrate including a ScAlN layer configured to provide a buffer layer of the HEMT device to confine formation of a 2DEG channel region of the HEMT device. An RF piezoelectric resonator device can be on the substrate including the ScAlN layer sandwiched between a top electrode and a bottom electrode of the RF piezoelectric resonator device to provide a piezoelectric resonator for the RF piezoelectric resonator device.

Aspects of this disclosure relate to bulk acoustic wave resonators. A bulk acoustic wave resonator includes a patterned mass loading layer that affects a resonant frequency of the bulk acoustic wave resonator. The patterned mass loading layer can have a duty factor in a range from 0.2 to 0.8 in a main acoustically active region of the bulk acoustic wave resonator. Related filters, acoustic wave dies, radio frequency modules, wireless communications devices, and methods are disclosed.

A single crystal piezoelectric layer includes a first recess in a first opposing surface opposing a first main surface of a base. The single crystal piezoelectric layer is bonded to the first main surface of the base at a portion of the first opposing surface other than the first recess. A lower electrode layer defining at least a portion of a pair of electrode layers and extending over a surface of the single crystal piezoelectric layer opposing the base is at least partially located in the first recess. A second opposing surface of the lower electrode layer opposing the first main surface of the base has surface roughness greater than the surface roughness of the first opposing surface of the single crystal piezoelectric layer.

A bulk-acoustic wave resonator may include: a substrate; a resonance portion; a first electrode disposed on the substrate; a piezoelectric layer disposed on the first electrode in the resonance portion; a second electrode disposed on the piezoelectric portion in the resonance portion; and a seed layer disposed in a lower portion of the first electrode. The seed layer may be formed of titanium (Ti) having a hexagonal close packed (HCP) structure, or an alloy of Ti having the HCP structure. The seed layer may have a thickness greater than or equal to 300 Å and less than or equal to 1000 Å, or may be thinner than the first electrode.

A film bulk acoustic resonator includes: a first electrode disposed on a substrate; a piezoelectric body disposed on the first electrode and including AlN to which a dopant is added; and a second electrode disposed on the piezoelectric body and facing the first electrode such that the piezoelectric body is interposed between the second electrode and the first electrode, wherein the dopant includes either one of 0.1 to 24 at % of Ta and 0.1 to 23 at % of Nb.

A bulk-acoustic wave resonator includes: a first electrode; a piezoelectric layer at least partially disposed on an upper portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The second electrode includes a frame disposed at an edge of an active region of the bulk-acoustic wave resonator, and the first electrode, the piezoelectric layer and the second electrode are disposed to overlap one another at the edge of the active region. The frame includes a wall disposed at the edge of the active region and a trench formed on an internal side of the wall. An internal boundary line of the trench has a concave-convex shape in a plane parallel to an upper surface of the frame.

A bulk-acoustic wave resonator includes: a substrate; a membrane layer forming a cavity with the substrate; a lower electrode disposed on the membrane layer; an insertion layer disposed to cover at least a portion of the lower electrode; a piezoelectric layer disposed on the lower electrode to cover the insertion layer; and an upper electrode at least partially disposed on the piezoelectric layer, wherein the upper electrode includes a reflection groove disposed on the insertion layer.