A bulk acoustic filter device includes: a substrate including a through hole formed by a first recess and a second recess adjacent to the first recess; a membrane layer forming a cavity with the substrate; a filter including a lower electrode disposed on the membrane layer, a piezoelectric layer disposed to cover a portion of the lower electrode, and an upper electrode formed to cover a portion of the piezoelectric layer; and an electrode connecting member disposed in the substrate, and connected to either one of the lower electrode and the upper electrode, wherein the electrode connecting member includes an insertion electrode disposed in the first recess, and a via electrode connected to the insertion electrode, and disposed on an inner peripheral surface of the second recess and a surface of the substrate.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. An acoustic reflector electrode may include a first pair of top metal electrode layers electrically and acoustically coupled with the first and second layer of piezoelectric material to excite the piezoelectrically excitable resonance mode at a resonant frequency of the BAW resonator. The acoustic reflector may include a patterned layer.

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.

Techniques are disclosed for forming a monolithic integrated circuit semiconductor structure that includes a radio frequency (RF) frontend portion and may further include a CMOS portion. The RF frontend portion includes componentry implemented with column III-N semiconductor materials such as gallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN), and compounds thereof, and the CMOS portion includes CMOS logic componentry implemented with semiconductor materials selected from group IV of the periodic table, such as silicon, germanium, and/or silicon germanium (SiGe). Either of the CMOS or RF frontend portions can be native to the underlying substrate to some degree. The techniques can be used, for example, for system-on-chip integration of III-N transistors and/or RF filters, along with column IV CMOS devices on a single substrate. In a more general sense, the techniques can be used for SoC integration of an RF frontend having diverse III-N componentry on a single substrate, in accordance with some embodiments.

A radio frequency (RF) front-end (RFFE) device includes a die having a front-side dielectric layer on an active device. The active device is on a first substrate. The RFFE device also includes a microelectromechanical system (MEMS) device. The MEMS device is integrated on the die at a different layer than the active device. The MEMS device includes a cap layer composed of a cavity in the front-side dielectric layer of the die. The cavity in the front-side dielectric layer is between the first substrate and a second substrate. The cap is coupled to the front-side dielectric layer.

The RF filters used in conventional mobile devices often include resonator structures, which often require free-standing air-gap structure to prevent mechanical vibrations of the resonator from being damped by a bulk material. A method for fabricating a resonator structure comprises depositing a non-conformal thin-film to the resonator structure to seal air gap cavities in the resonator structure.

A resonator includes a resonating portion including a first electrode, a second electrode, and a piezoelectric layer positioned between the first electrode and the second electrode; and a frame provided at an outer edge of the resonating portion, at least a portion of the frame covering an outer end portion of the second electrode.

A Bulk Acoustic Resonator (BAR) structure has a substrate. A cavity pattern is formed on the substrate. A Bulk Acoustic Wave (BAW) structure is formed on the cavity pattern and the substrate, wherein portions of the cavity pattern are exposed. The cavity pattern under the BAW structure is removed creating a self-sustaining cavity to form the novel cavity structure.

A filter package comprising an array of piezoelectric films comprising an array of mixed single crystals that each comprise doped Aluminum Nitride, typically Al.sub.xGa.sub.(1-x)N or Sc.sub.xAl.sub.(1-x)N, that is sandwiched between an array of lower electrodes and an array of upper electrodes comprising metal layers and silicon membranes with cavities thereover: the array of lower electrodes being coupled to an interposer with a first cavity between the array of lower electrodes and the interposer; the array of silicon membranes having a known thickness and attached over the array of upper electrodes with an array of upper cavities, each upper cavity between a silicon membrane of the array and a common silicon cover; each upper cavity aligned with a piezoelectric film, an upper electrode and silicon membrane, the upper cavities having side walls comprising SiO.sub.2; the individual piezoelectric films, their upper electrodes and silicon membranes thereover being separated from adjacent piezoelectric films, upper electrodes and silicon membranes by a passivation material.

A piezoelectric thin film suspended above a carrier substrate is adapted to propagate an acoustic wave in a Lamb mode excited by a component of an electric field that is oriented in a longitudinal direction along a length of the piezoelectric thin film. A first signal electrode is located on the piezoelectric thin film and oriented in a transverse direction perpendicular to the longitudinal direction. A first ground electrode is located on the piezoelectric thin film and oriented in the transverse direction. The first ground electrode is separated from the first signal electrode by a gap in which the acoustic wave resonates. A first release window and a second release window are located at a first end and a second end of the piezoelectric thin film, respectively. Intermittent release windows are located beyond distal ends of the first signal electrode and the first ground electrode.