Abstract: A bulk acoustic wave (BAW) resonator includes a substrate defining a cavity, a bottom electrode disposed over the substrate and the cavity, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer. The piezoelectric layer includes polycrystalline lithium niobate (LN) material or polycrystalline lithium tantalite (LT) material. The BAW resonator may further include an encapsulant layer formed on side and top surfaces of the piezoelectric layer. The encapsulant layer is configured to protect the LN material or the LT material of the piezoelectric layer from a release solvent previously applied to sacrificial material within the cavity in the substrate.

Abstract: A method of forming an acoustic resonator includes forming a seed layer on a first electrode layer, forming a piezoelectric layer directly on a surface of the seed layer, and forming a second electrode layer on the piezoelectric layer. The piezoelectric layer includes multiple crystals of piezoelectric material, and the seed layer causes crystal axis orientations of the crystals to be substantially perpendicular to the surface of the seed layer.

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 piezoelectric layer. The piezoelectric layer includes undoped piezoelectric material and doped piezoelectric material, where the doped piezoelectric material is doped with at least one rare earth element, for improving piezoelectric properties of the piezoelectric layer and reducing compressive stress.

Abstract: An acoustic resonator structure comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode and comprising aluminum scandium nitride, a second electrode disposed on the piezoelectric layer, and a temperature compensation feature having a temperature coefficient offsetting at least a portion of a temperature coefficient of the piezoelectric layer, the first electrode, and the second electrode.

Abstract: An acoustic resonator device includes a bottom electrode disposed on a substrate over an air cavity, a first piezoelectric material layer disposed on the bottom electrode, an electrically-isolated layer of high-acoustic-impedance material disposed on the first piezoelectric material layer, a second piezoelectric material layer disposed on the electrically-isolated layer of high-acoustic impedance material, and a top electrode disposed on the second piezoelectric material layer, where an overlap among the top electrode, the first piezoelectric material layer, the electrically-isolated layer of high-acoustic-impedance material, the second piezoelectric material layer, and the bottom electrode over the air cavity defines a main membrane region.

Abstract: An acoustic resonator structure comprises a piezoelectric layer having a first surface and a second surface, a first electrode disposed adjacent to the first surface, and a second electrode disposed adjacent to the second surface. The first electrode comprises a first conductive layer disposed adjacent to the piezoelectric layer and having a first acoustic impedance, and a second conductive layer disposed on a side of the first conductive layer opposite the piezoelectric layer and having a second acoustic impedance greater than the first acoustic impedance. The second electrode may be disposed between a substrate and the piezoelectric layer, and it may comprise a third conductive layer disposed adjacent to the piezoelectric layer and having a third acoustic impedance, and a fourth conductive layer disposed on a side of the third conductive layer opposite the piezoelectric layer and having a fourth acoustic impedance greater than the third acoustic impedance.

Abstract: A bulk acoustic wave (BAW) resonator includes a first electrode; a second electrode; and a piezoelectric layer disposed between the first and second electrodes. The piezoelectric layer includes a piezoelectric material doped with at least one rare earth element. In an embodiment, the BAW resonator includes a recessed frame element disposed over a surface of at least one of the first and second electrodes. In another embodiment, the BAW resonator includes a raised frame element disposed over a surface of at least one of the first and second electrodes. In yet another embodiment, the BAW resonator includes both the raised and recessed frame elements.

Abstract: An acoustic resonator structure includes a bottom electrode disposed on a substrate, a piezoelectric layer disposed on the bottom electrode, a top electrode disposed on the piezoelectric layer, a cavity disposed beneath the bottom electrode, and a temperature compensating feature. The temperature compensating feature has a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric and electrode layers. The acoustic resonator structure further includes an acoustic reflector disposed over the substrate around a perimeter of the cavity. The acoustic reflector includes a layer of low acoustic impedance material stacked on a layer of high acoustic impedance material.

Abstract: An acoustic resonator structure includes an acoustic reflector over a cavity formed in a substrate, the acoustic reflector including a layer of low acoustic impedance material stacked on a layer of high acoustic impedance material. The acoustic resonator further includes a bottom electrode on the layer of low acoustic impedance material, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and a collar formed outside a main membrane region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode. The collar has an inner edge substantially aligned with a boundary of or overlapping the main membrane region. The layer of the low acoustic impedance material includes a temperature compensating material having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, the bottom electrode and the top electrode.

Abstract: An acoustic resonator structure comprises a substrate having an air cavity, an acoustic stack disposed over the substrate and comprising a piezoelectric material disposed between a first electrode and a second electrode, and an acoustic reflector disposed over the substrate and comprising a single pair of acoustic impedance layers configured to reflect acoustic waves produced by vibration of the acoustic stack, wherein at least one of the acoustic impedance layers comprises a temperature compensating material.

Abstract: In accordance with a representative embodiment, a bulk acoustic wave (BAW) resonator comprises: a first electrode having a first electrode thickness; a second electrode having a second electrode thickness; and a piezoelectric layer having a piezoelectric layer thickness and being disposed between the first and second electrodes, the piezoelectric layer comprising a piezoelectric material doped with at least one rare earth element. For a particular acoustic coupling coefficient (kt2) value and a series resonance frequency (Fs) of the BAW resonator, the first electrode thickness and the second electrode thickness are each greater than a thickness of a first electrode and a thickness of a second electrode of a BAW resonator comprising an undoped piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator device includes a bottom electrode on a substrate over one of a cavity and an acoustic mirror, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and a temperature compensation feature having positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer. At least one of the bottom electrode and the top electrode includes an integrated lateral feature configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch.

Abstract: A bulk acoustic wave (BAW) resonator device includes a bottom electrode on a substrate over one of a cavity and an acoustic mirror, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and a temperature compensation feature having positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer. At least one of the bottom electrode and the top electrode includes an integrated lateral feature configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch.

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: An electrical resonator comprises a substrate comprising a cavity. The electrical resonator comprises a resonator stack suspended over the cavity. The resonator stack comprises a first electrode; a second electrode; a piezoelectric layer; and a temperature compensating layer comprising borosilicate glass (BSG).

Abstract: An acoustic resonator comprises a substrate comprising a cavity. The electrical resonator comprises a resonator stack suspended over the cavity. The resonator stack comprises a first electrode; a second electrode; a piezoelectric layer; and a temperature compensating layer comprising borosilicate glass (BSG).

Abstract: A bulk acoustic wave (BAW) resonator having a first electrode, a second electrode, and a piezoelectric layer between the first electrode and the second electrode. The first electrode is of a first electrode material. The second electrode is of a second electrode material. The piezoelectric layer is of a piezoelectric material doped with at least one rare earth element. The BAW resonator has a resonant frequency dependent at least in part on respective thicknesses and materials of the first electrode, the second electrode and the piezoelectric layer. The resonant frequency has a temperature coefficient. At least one of the first electrode and the second electrode includes a niobium alloy electrode material that, relative to molybdenum as the electrode material, reduces the temperature coefficient of the resonant frequency of the BAW resonator.

Abstract: A plasma vapor deposition (PVD) system and method for depositing a piezoelectric layer over a substrate are disclosed. A plasma is created in a reaction chamber creates from the sputtering gas supplied to the reaction chamber. The plasma sputters atoms from the sputtering target, which are deposited on the substrate for forming the thin film of the material.

Abstract: An acoustic resonator structure comprises a piezoelectric layer having a first surface and a second surface, a first electrode disposed adjacent to the first surface, and a second electrode disposed adjacent to the second surface. The first electrode comprises a first conductive layer disposed adjacent to the piezoelectric layer and having a first acoustic impedance, and a second conductive layer disposed on a side of the first conductive layer opposite the piezoelectric layer and having a second acoustic impedance greater than the first acoustic impedance. The second electrode may be disposed between a substrate and the piezoelectric layer, and it may comprise a third conductive layer disposed adjacent to the piezoelectric layer and having a third acoustic impedance, and a fourth conductive layer disposed on a side of the third conductive layer opposite the piezoelectric layer and having a fourth acoustic impedance greater than the third acoustic impedance.

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 multiple rare earth elements for improving piezoelectric properties of the piezoelectric layer.