A process for fabricating a transversely-excited film bulk acoustic resonator (XBAR) and that XBAR are described. A sacrificial pillar is formed on a surface of a piezoelectric wafer and a highly conforming dielectric layer is deposited on the piezoelectric wafer to bury the sacrificial pillar. The highly conforming dielectric layer is polished to form a planar surface and to leave a thickness of the highly conforming dielectric that covers the sacrificial pillar. The planar surface of the highly conforming dielectric layer is bonded to a surface of a substrate wafer. A conductor pattern is formed on a front surface of the piezoelectric plate and holes are formed through the piezoelectric wafer to the sacrificial pillar. The sacrificial pillar is removed using an etchant introduced through the holes in the piezoelectric wafer to form a cavity under a diaphragm of the piezoelectric wafer spanning the cavity.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.

A process for fabricating a transversely-excited film bulk acoustic resonator (XBAR) having a metal cavity, and the fabricated XBAR include forming a conductor pattern including interleaved interdigital transducer (IDT) fingers on a piezoelectric wafer. Thein forming a metal layer on a substrate, the metal layer having a cavity. Then, bonding the piezoelectric plate to the metal layer using a metal-to-metal bond such that the IDT fingers are disposed over the cavity. Then, thinning the piezoelectric wafer to form a piezoelectric plate having a portion of the piezoelectric plate forming a diaphragm that spans the cavity.

Acoustic resonator devices and methods are disclosed. An acoustic resonator device includes a substrate having a front surface and an intervening oxide layer on the front surface and having a cavity. A thickness of the intervening oxide layer defines a depth of the cavity, and the substrate has vertical etch-stop material for etching the intervening oxide layer. Lateral fences formed in the intervening oxide layer define a perimeter of the cavity. The lateral fences has a lateral etch-stop material for etching the intervening oxide layer. A single-crystal piezoelectric plate has a back surface attached to the front surface of the intervening oxide layer except for a portion of the piezoelectric plate forming a diaphragm that spans the cavity. An interdigital transducer is formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm.

The disclosure provides a film bulk acoustic resonator and a manufacturing method therefor, and a film bulk acoustic wave filter, and relates to the technical field of resonators. The film bulk acoustic resonator includes a substrate, where the substrate is provided with two opposite protective walls protruding out of a surface of the substrate, a cavity is formed between the two protective walls, and an insulating layer is further arranged on one side, away from the cavity, of each protective wall on the substrate; and the film bulk acoustic resonator further includes a transducer stacking structure, where the transducer stacking structure covers the insulating layer, the cavity and the protective walls, and two sides, along a stacking direction, of the transducer stacking structure are in communication with the cavity and the outside respectively. With the cavity formed through the protective walls, the cavity being in communication with the outside, and the cavity formed by releasing corrosive substances to the cavity area from the outside, accurate control over cavity release machining is achieved, a process is simpler, cost is controlled, and a process period is shortened; an area proportion of the protective walls is small, and a chemical mechanical polishing (CMP) requirement is low, so as to advantageously improve a yield; and a structure of the film bulk acoustic resonator is built on the insulating layer, so as to advantageously reduce parasitic capacitance and resistance and improve comprehensive device performance.

A bulk acoustic wave resonator is provided. The bulk acoustic wave resonator incudes a carrier substrate, having a main surface extending along a first direction; a piezoelectric layer, located on a side of the carrier substrate in a second direction perpendicular to the main surface of the carrier substrate; a first electrode and a second electrode; a cavity boundary structure, having a body part extending along the first direction and a protruding part protruding from the body part toward the piezoelectric layer; a resonant cavity, defined by the cavity boundary structure and the piezoelectric layer; and a periphery dielectric layer, located on a side of the protruding part of the cavity boundary structure away from the resonant cavity, a material of the periphery dielectric layer is different from a material of at least a portion of the protruding part adjacent to the periphery dielectric layer.

An acoustic resonator that has a first electrode with a first planar portion. A second electrode having a second planar portion is disposed parallel to the first planar portion. This second electrode has a bifurcated end that defines a gap. A piezoelectric layer is disposed between and contacts both the first planar portion and the second planar portion. Also contacting the piezoelectric layer is the bifurcated end of the second electrode. The gap is formed in the periphery of each resonator within a filter. It is formed in the top electrode, that is typically formed of molybdenum, but could be formed from other metals as well. Unlike a gap between a top electrode and piezoelectric material, the gap recited herein is entirely within the second electrode. This structure is compatible with an inner passivation layer that enables a single crystal piezoelectric layer and a larger bottom electrode.

An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.

A front-end module (FEM) for a 6.1 GHz Wi-Fi acoustic wave resonator RF filter circuit. The device can include a power amplifier (PA), a 6.1 GHz resonator, and a diversity switch. The device can further include a low noise amplifier (LNA). The PA is electrically coupled to an input node and can be configured to a DC power detector or an RF power detector. The resonator can be configured between the PA and the diversity switch, or between the diversity switch and an antenna. The LNA may be configured to the diversity switch or be electrically isolated from the switch. Another 6.1 GHZ resonator may be configured between the diversity switch and the LNA. In a specific example, this device integrates a 6.1 GHz PA, a 6.1 GHZ bulk acoustic wave (BAW) RF filter, a single pole two throw (SP2T) switch, and a bypassable LNA into a single device.

A BAW resonator with an improved lateral energy confinement is provided. The resonator has a bottom electrode in a bottom electrode layer, a top electrode in a top electrode layer and a piezoelectric layer between the bottom electrode layer and the top electrode layer. The piezoelectric layer comprises piezoelectric materials of different piezoelectric polarities.