Abstract: A bulk acoustic wave (BAW) resonator comprises: a seed layer disposed over a substrate; a first electrode disposed over the seed layer; and a second electrode disposed over a piezoelectric layer. The seed layer has a thickness in the range of approximately 30 ? to approximately 150 ?.

Abstract: A method is provided for forming a piezoelectric layer during a corresponding deposition sequence. The method includes sputtering aluminum nitride onto a sputtering substrate inside a reaction chamber having a gas atmosphere, the gas atmosphere initially including nitrogen gas and an inert gas, causing growth of the piezoelectric layer with a polarity in a negative direction. The method further includes adding a predetermined amount of oxygen containing gas to the gas atmosphere over a predetermined period of time, while continuing the sputtering of the aluminum nitride onto the sputtering substrate during a remainder of the deposition sequence, such that the piezoelectric layer is monolithic. The predetermined amount of oxygen containing gas causes the polarity of the aluminum nitride piezoelectric layer to invert from the negative direction to a positive direction, opposite the negative direction.

Abstract: An acoustic resonator device includes a composite first electrode disposed over a substrate; a piezoelectric layer disposed on the composite first electrode, the piezoelectric layer including a piezoelectric material doped with scandium for improving piezoelectric properties of the piezoelectric layer; and a second electrode disposed on the piezoelectric layer. The composite first electrode includes a base electrode layer disposed over the substrate; a temperature compensation layer disposed on the base electrode layer; a seed interlayer disposed on the temperature compensation layer, the seed interlayer having a thickness between about 5 ? and about 150 ?; and a conductive interposer layer disposed on at least the seed interlayer, at least a portion of the conductive interposer layer contacting the base electrode layer.

Abstract: An acoustic resonator structure comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode, a second electrode disposed on the piezoelectric layer, and an air cavity disposed in the substrate below at least a portion of a main membrane region defined by an overlap between the first electrode. The acoustic resonator structure may further comprise various integrated structures at or around the main membrane region to improve its electrical performance.

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 solid mount bulk acoustic wave resonator, comprises a first electrode; a second electrode; a piezoelectric layer disposed between the first and second electrodes; and an acoustic reflector comprising a plurality of layers and disposed beneath the first electrode, the second electrode and the piezoelectric layer. An overlap of the acoustic reflector, the first electrode, the second electrode and the piezoelectric layer defines an active area of the acoustic resonator, and the piezoelectric layer extends over an edge of the first electrode. The acoustic resonator also comprises a bridge adjacent to a termination of the active area of the acoustic resonator. The bridge overlaps a portion of the first electrode.

Abstract: An acoustic resonator comprises a first electrode and second electrode comprising a plurality of sides. At least one of the sides of the second electrode comprises a cantilevered portion. A piezoelectric layer is disposed between the first and second electrodes. A bridge disposed adjacent to one of the sides of the second electrode.

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: A solidly mounted resonator (SMR) includes an acoustic resonator on a substrate, the acoustic resonator having multiple acoustic impedance layers having different acoustic impedances, respectively. The SMR further includes a bottom electrode on a top acoustic impedance layer of the plurality of acoustic impedance layers, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and multiple lateral features on a surface of the top electrode. The lateral features include multiple stepped structures.

Abstract: An acoustic resonator device includes a bottom electrode disposed on a substrate over an acoustic reflecting feature, a piezoelectric layer disposed on the bottom electrode and a top electrode disposed on the piezoelectric layer, where an overlap between the top electrode, the piezoelectric layer and the bottom electrode over the acoustic reflecting feature define an active region of the acoustic resonator device. The acoustic resonator device further includes at least one of a wing having an outer edge extending beyond at least a portion of an outer edge of the top electrode, and a first frame formed in one of an outer region or a center region of the top electrode. The at least one of the wing and the first frame has an apodized shape, such that no edges are parallel to one another, the apodized shape of the at least one of the wing and the first frame being different from an electrode shape defined by an outer edge of the top electrode.

Abstract: In a representative embodiment, a bulk acoustic wave (BAW) resonator, comprises: a cavity disposed in a substrate; a first electrode disposed over the cavity; a planarization layer disposed adjacent to the first electrode; a piezoelectric layer disposed over the first electrode; and a second electrode disposed over the piezoelectric layer.

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 comprises a first electrode and second electrode comprising a plurality of sides. At least one of the sides of the second electrode comprises a cantilevered portion. A piezoelectric layer is disposed between the first and second electrodes. A bridge disposed adjacent to one of the sides of the second electrode.

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 comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode, a second electrode disposed on the piezoelectric layer, a frame disposed within a main membrane region defined by an overlap between the first electrode, the piezoelectric layer, and the second electrode, and having an outer edge substantially aligned with a boundary of the main membrane region, and a collar formed separate from the frame, disposed outside the main membrane region, and having an inner edge substantially aligned with the boundary of or overlapping the main membrane region.

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: An acoustic resonator device includes a bottom electrode disposed on a substrate over an air cavity, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer, where an overlap between the top electrode, the piezoelectric layer and the bottom electrode over the air cavity defines a main membrane region. The acoustic resonator device further includes at least one metal frame disposed on a bottom surface of the bottom electrode having a thickness that ranges from about 10% to about 75% of a thickness of the bottom electrode in a central region of the bottom electrode. The thickness of the metal frame improves heat dissipation out of the acoustic resonator device while also improving structural stability of the acoustic resonator device without detrimentally affecting its performance.