Abstract: A BAW resonator comprises: a substrate comprising an acoustic reflector; a first electrode disposed over the acoustic reflector, and comprising a first electrode layer comprising a comparatively high acoustic impedance material, and a second electrode layer comprising a comparatively low acoustic impedance; a piezoelectric layer disposed over the second electrode layer; and a second electrode disposed over the piezoelectric layer, and comprising a third electrode layer comprising the low acoustic impedance, and a fourth electrode layer comprising the comparatively high acoustic impedance material and being disposed directly on the piezoelectric layer. A total thickness of an acoustic stack of the BAW resonator is approximately ?/2, where ? is a wavelength corresponding to a thickness extensional resonance frequency of the BAW resonator.

Abstract: A BAW resonator comprises: a substrate comprising an acoustic reflector; a first electrode disposed over the acoustic reflector, and comprising a first electrode layer comprising a comparatively high acoustic impedance material, and a second electrode layer comprising a comparatively low acoustic impedance; a piezoelectric layer disposed over the second electrode layer; and a second electrode disposed over the piezoelectric layer, and comprising a third electrode layer comprising the low acoustic impedance, and a fourth electrode layer comprising the comparatively high acoustic impedance material and being disposed directly on the piezoelectric layer. A total thickness of an acoustic stack of the BAW resonator is approximately ?/2, where ? is a wavelength corresponding to a thickness extensional resonance frequency of the BAW resonator.

Abstract: A bulk acoustic wave (BAW) resonator includes: an acoustic reflector disposed in a substrate; a lower electrode disposed over the acoustic reflector; a piezoelectric layer disposed over the lower electrode; and an upper electrode disposed over the piezoelectric layer. A contacting overlap of the lower electrode, the piezoelectric layer and the upper electrode over the acoustic reflector comprising an active area of the BAW resonator. An opening exists in the upper electrode in a region of the BAW resonator susceptible to unacceptable overheating.

Abstract: A bulk acoustic wave (BAW) resonator includes: an acoustic reflector disposed in a substrate; a lower electrode disposed over the acoustic reflector; a piezoelectric layer disposed over the lower electrode; and an upper electrode disposed over the piezoelectric layer. A contacting overlap of the lower electrode, the piezoelectric layer and the upper electrode over the acoustic reflector comprising an active area of the BAW resonator. An opening exists in the upper electrode in a region of the BAW resonator susceptible to unacceptable overheating.

Abstract: An apparatus includes a silicon (Si) substrate having a first surface and a second surface, the silicon substrate having a resistivity at room temperature greater than approximately 1000 ?-cm, and less than approximately 15000 ?-cm; and a piezoelectric layer disposed over the substrate and having a first surface and a second surface. The piezoelectric layer may have a thickness in the range of approximately 0.5 ?m to approximately 30.0 ?m, and is substantially without iron (Fe).

Abstract: A bulk acoustic wave (BAW) resonator includes: an acoustic reflector disposed in a substrate; a lower electrode disposed over the acoustic reflector; a piezoelectric layer disposed over the lower electrode; and an upper electrode disposed over the piezoelectric layer. A contacting overlap of the lower electrode, the piezoelectric layer and the upper electrode over the acoustic reflector comprising an active area of the BAW resonator. An opening exists in the upper electrode in a region of the BAW resonator susceptible to unacceptable overheating.

Abstract: An apparatus includes a silicon (Si) substrate having a first surface and a second surface, the silicon substrate having a resistivity at room temperature greater than approximately 1000 ?-cm, and less than approximately 15000 ?-cm; and a piezoelectric layer disposed over the substrate and having a first surface and a second surface. The piezoelectric layer may have a thickness in the range of approximately 0.5 ?m to approximately 30.0 ?m, and is substantially without iron (Fe).

Abstract: A method of fabricating a rare-earth element doped piezoelectric material having a first component, a second component and the rare-earth element. The method includes: providing a substrate; initially flowing hydrogen over the substrate; after the initially flowing of the hydrogen over the substrate, flowing the first component to form the rare-earth element doped piezoelectric material over a surface of a target, the target comprising the rare-earth metal in a certain atomic percentage; and sputtering the rare-earth element doped piezoelectric material from the target on the substrate.

Abstract: A surface acoustic wave (SAW) resonator structure includes a substrate, a piezoelectric layer disposed on the substrate, and an interdigital transducer (IDT) electrode disposed over the piezoelectric layer. The IDT electrode includes multiple busbars and multiple electrode fingers extending from each busbar, where the electrode fingers are configured to generate surface acoustic waves in the piezoelectric layer. The SAW resonator structure further includes dielectric material disposed between the piezoelectric layer and at least at portion of the IDT. The dielectric material may be positioned below tips of the electrode fingers, thereby mass-loading the electrode fingers.

Abstract: A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with one of erbium or yttrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator structure comprises: a first electrode disposed over a substrate; a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising boron nitride (BN); and a second electrode disposed over the first piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode, and a second electrode disposed over the first piezoelectric layer. A bridge is formed within the piezoelectric layer, where the bridge is surrounded by piezoelectric material of the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator structure comprises: a first electrode disposed over a substrate; a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising boron nitride (BN); and a second electrode disposed over the first piezoelectric layer.

Abstract: A method of fabricating a rare-earth element doped piezoelectric material having a first component, a second component and the rare-earth element. The method includes: providing a substrate; initially flowing hydrogen over the substrate; after the initially flowing of the hydrogen over the substrate, flowing the first component to form the rare-earth element doped piezoelectric material over a surface of a single target, the target comprising the rare-earth metal in a certain atomic percentage; and sputtering the rare-earth element doped piezoelectric material from the target on the substrate.

Abstract: In a representative embodiment, a bulk acoustic wave (BAW) resonator, comprises: a first electrode disposed over a substrate; a first piezoelectric layer disposed over the first electrode, the first piezoelectric layer having a first c-axis oriented along a first direction; a second electrode disposed over the first piezoelectric layer; and a second piezoelectric layer disposed over the first electrode and adjacent to the first piezoelectric layer, wherein the second piezoelectric layer has a second c-axis oriented in a second direction that is substantially antiparallel to the first direction.

Abstract: A method of fabricating a rare-earth element doped piezoelectric material having a first component, a second component and the rare-earth element. The method includes: providing a substrate; initially flowing hydrogen over the substrate; after the initially flowing of the hydrogen over the substrate, flowing the first component to form the rare-earth element doped piezoelectric material over a surface of a target, the target comprising the rare-earth metal in a certain atomic percentage; and sputtering the rare-earth element doped piezoelectric material from the target on the substrate.

Abstract: A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with one of erbium or yittrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer.

Abstract: In accordance with a representative embodiment, a method, comprises: providing a substrate; forming a first piezoelectric layer having a compression-negative (CN) polarity over the substrate; and forming a second piezoelectric layer having a compression-positive (CP) over the substrate and adjacent to the first piezoelectric layer.

Abstract: In accordance with a representative embodiment, a bulk acoustic wave (BAW) resonator structure, comprises: a first BAW resonator comprising a first lower electrode, a first upper electrode and a first piezoelectric layer disposed between the first lower electrode and the first upper electrode; a second BAW resonator comprising a second lower electrode, a second upper electrode and a second piezoelectric layer disposed between the second lower electrode and the second upper electrode; and a single-material acoustic coupling layer disposed between the first and second BAW resonators, the acoustic coupling layer having an acoustic impedance less than approximately 6.0 MRayls and an acoustic attenuation less than approximately 1000 dB/cm.

Abstract: In a representative embodiment, a bulk acoustic wave (BAW) resonator, comprises: a first electrode disposed over a substrate; a first piezoelectric layer disposed over the first electrode, the first piezoelectric layer having a first c-axis oriented along a first direction; a second electrode disposed over the first piezoelectric layer; and a second piezoelectric layer disposed over the first electrode and adjacent to the first piezoelectric layer, wherein the second piezoelectric layer has a second c-axis oriented in a second direction that is substantially antiparallel to the first direction.