A bulk acoustic resonator includes: a substrate; a first electrode disposed on the substrate; a piezoelectric layer disposed to cover at least a portion of the first electrode; a second electrode disposed to cover at least a portion of the piezoelectric layer; a metal pad connected to the first electrode and the second electrode; and a protective layer disposed to cover at least the metal pad.

The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator, which includes a bottom electrode, a top electrode structure, and a ferroelectric layer sandwiched in between. Herein, the ferroelectric layer is formed of a ferroelectric material, which has a box-shape polarization-electric field (P-E) curve. The ferroelectric layer includes a ferroelectric border (BO) portion positioned at a periphery of the ferroelectric layer and a ferroelectric central portion surrounded by the ferroelectric BO portion. The ferroelectric BO portion has a first polarization and a first electromechanical coupling coefficient, and the ferroelectric central portion has a second polarization and a second electromechanical coupling coefficient. An absolute value of the first polarization is less than an absolute value of the second polarization, and the first electromechanical coupling coefficient is less than the second electromechanical coupling coefficient. The ferroelectric central portion is configured to provide a resonance of the BAW resonator.

The present disclosure relates to a Bulk Acoustic Wave (BAW) resonator, which includes a bottom electrode, a top electrode structure, and a multilayer transduction structure sandwiched therebetween. Herein, the multilayer transduction structure is composed of multiple transduction layers, at least one of which is formed of a ferroelectric material with a box-shape polarization-electric field curve. Each transduction layer includes a transduction border (BO) portion positioned at a periphery of a corresponding transduction layer and a transduction central portion surrounded by the transduction BO portion. A combination of all transduction BO portions forms a transduction BO section of the multilayer transduction structure, and a combination of all transduction central portions forms a transduction central section of the multilayer transduction structure. An electromechanical coupling coefficient of the transduction BO section is less than an electromechanical coupling coefficient of the transduction central section.

A bulk-acoustic wave resonator may include: a substrate; a resonator unit including a first electrode disposed on the substrate, a piezoelectric layer disposed on the first electrode, and a second electrode disposed on the piezoelectric layer; and a protective layer disposed on a surface of the resonator unit. The protective layer is formed of a diamond film, and a grain size of the diamond film is 50 nm or more.

A resonator includes a silicon substrate, a bottom electrode stacked on a portion of the silicon substrate, a piezoelectric layer covering the bottom electrode and another portion of the silicon substrate, a top electrode stacked on the piezoelectric layer, and a Bragg reflecting ring. The Bragg reflecting ring is formed on a side of the piezoelectric layer connected to the top electrode and surrounds the top electrode. The Bragg reflecting ring includes a Bragg high-resistivity layer and a Bragg low-resistivity layer alternately arranged along the radial direction of the Bragg reflecting ring. An acoustic impedance of the Bragg high-resistivity layer is greater than an acoustic impedance of the Bragg low-resistivity layer. The Bragg reflecting ring forms reflection surfaces to reflect the laterally propagating clutter waves, thereby suppressing the parasitic mode in the working frequency band, improving the frequency response curve of the resonator and the overall performance of the resonator.

An acoustic wave device includes a support substrate, a piezoelectric layer, and a functional electrode. As seen in a first direction of the support substrate, the piezoelectric layer overlaps the support substrate. The functional electrode extends over a first major surface of the piezoelectric layer. A space is opposite to the first major surface of the piezoelectric layer and at or adjacent to a second major surface of the piezoelectric layer. In the first direction, the functional electrode extends over an overlap region that overlaps the space, and a non-overlap region that does not overlap the space. In the non-overlap region, at least one of an insulating film and a void is located between the functional electrode and the piezoelectric layer.

An acoustic resonator with a reinforcing structure is provided according to the present disclosure. The acoustic resonator includes a substrate and a cavity formed on the substrate, a piezoelectric layer is arranged above the substrate and an opening passing through the piezoelectric layer is formed in a peripheral region of the piezoelectric layer. The reinforcing structure includes a reinforcing layer, part of the reinforcing layer is formed at the edge of the opening with being fitted to the edge, to reinforce a resonant functional layer near the edge of the opening, which can reduce a change in stress of the piezoelectric layer and the lower electrode near the edge of the opening after the cavity is released, so that the piezoelectric layer and the lower electrode do not easily collapse due to stress, thereby ensuring the performance of a device. A method for manufacturing the same is further provided.

An acoustic resonator package is provided. The acoustic resonator package includes a substrate, a cap, a plurality of acoustic resonators disposed between the substrate and the cap and configured to be electrically connected to each other, a grounding member disposed between the substrate and the cap, and a breakdown voltage shortener configured to provide an air gap to shorten a breakdown voltage between one of the plurality of acoustic resonators and the grounding member.

An acoustic wave device is provided comprising a substrate and at least one resonator structure of a first type and at least one resonator structure of a second type mounted on the substrate. The resonator structures of the first type are configured to operate as capacitors and have a first thickness, causing the resonator structures to have a first passband frequency range. The resonator structures of the second type have a second thickness that is different from the first thickness, causing the resonator structures to have a second passband frequency range. A method for forming such an acoustic wave device is also provided. A die comprising such an acoustic wave device, a filter comprising such an acoustic wave device, a radio-frequency module comprising such an acoustic wave device, and a wireless mobile device comprising such an acoustic wave device are also provided.

A bulk acoustic wave resonator includes a substrate; a central portion including a first portion of a first electrode, a first portion of a piezoelectric layer, and a first portion of a second electrode laminated in order on the substrate; and a reflective region disposed laterally of the central portion and including a second portion of the first electrode, an insertion layer, a second portion of the piezoelectric layer, and a second portion of the second electrode. A side surface of the insertion layer adjacent to the central portion has an inclined surface, the first portion of the second electrode and the second portion of the second electrode are coplanar, and an end of the second electrode overlaps the inclined surface of the insertion layer in the reflective region.