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 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: A method is provided for depositing a thin film of material on a substrate. The method includes providing the substrate on a cathode and a target on an anode in a reaction chamber of a magnetron sputtering device, generating a magnetic field using an enhanced magnetron including an upper base plate to generate an upper magnetic field having a field strength of about 205 gauss and a lower base plate to generate a lower magnetic field having a field strength of about ?215 gauss to about ?370 gauss, injecting sputtering gas at low pressure into the reaction chamber, and applying power across the anode and cathode to create plasma. Ions from the plasma sputter atoms of at least one element from the target, which are deposited on the substrate to form the thin film. Power density of the power is in a range of about 20 W/cm2 to about 60 W/cm2.

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 thin film bulk acoustic resonator (FBAR) includes a first electrode, a first piezoelectric layer having a first c-axis orientation and on the first electrode, a second piezoelectric layer having a second c-axis orientation over the first piezoelectric layer, and a second electrode on the second piezoelectric layer. The first and second piezoelectric layers are made of respective different piezoelectric materials. The FBAR can be set to have different resonance frequencies by selecting the first and second c-axis orientations to be respectively the same or different. The high and low frequency range of the FBAR can thus be extended.

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: 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: 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 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: 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 sputtering target comprises an alloy of scandium and aluminum, wherein the alloy has a concentration of 3-10 at % scandium and 90-97 at % aluminum. The sputtering target can be used to produce a piezoelectric layer for an apparatus such as an acoustic resonator.

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 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 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: 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.

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: 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 thin film bulk acoustic resonator (FBAR) includes a first electrode, a first piezoelectric layer having a first c-axis orientation and on the first electrode, a second piezoelectric layer having a second c-axis orientation over the first piezoelectric layer, and a second electrode on the second piezoelectric layer. The first and second piezoelectric layers are made of respective different piezoelectric materials. The FBAR can be set to have different resonance frequencies by selecting the first and second c-axis orientations to be respectively the same or different. The high and low frequency range of the FBAR can thus be extended.

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 device comprises a substrate, an acoustic stack, and a distributed Bragg reflector. The acoustic stack comprises a first electrode formed on the substrate, a first piezoelectric layer formed on the first electrode, a second electrode formed on the first piezoelectric layer, a second piezoelectric layer formed on the second electrode, and a third electrode formed on the second piezoelectric layer. The distributed Bragg reflector is formed adjacent to the acoustic stack and provides it with acoustic isolation.