An acoustic wave device assembly is disclosed. The acoustic wave device assembly can include a first interdigital transducer electrode that is in contact with a first piezoelectric layer, and a second interdigital transducer electrode that is in contact with a second piezoelectric layer. The acoustic wave device assembly can include an acoustic mirror structure that is positioned between the first interdigital transducer electrode and the second interdigital transducer electrode. The acoustic mirror structure has a first portion that is configured to confine acoustic energy of a first acoustic wave generated by the first interdigital transducer electrode, and a second portion that is configured to confine acoustic energy of a second acoustic wave generated by the second interdigital transducer electrode.

A stacked acoustic wave device assembly is disclosed. The stacked acoustic wave device assembly can include a first acoustic wave device that includes a first substrate, a first piezoelectric layer, a first solid acoustic mirror that is disposed between the first substrate and the first piezoelectric layer, and a first interdigital transducer electrode that is in contact with the first piezoelectric layer. The stacked acoustic wave device assembly can include a second acoustic wave device that includes a second substrate, a second piezoelectric layer, a second solid acoustic mirror that is disposed between the second substrate and the second piezoelectric layer, and a second interdigital transducer electrode that is in contact with the second piezoelectric layer. The second acoustic wave device is stacked over the first acoustic wave device. The first acoustic wave device and the second acoustic wave device are spaced by a spacer assembly such that a cavity is formed between the first acoustic wave device and the second acoustic wave device.

Aspects of this disclosure relate to method of manufacturing a bulk acoustic wave device. The method can include providing a bulk acoustic wave device structure including a first piezoelectric layer and forming a second piezoelectric layer over the first piezoelectric layer by atomic layer deposition. The second piezoelectric layer can have an opposite polarization relative to the first piezoelectric layer.

Aspects of this disclosure relate to a bulk acoustic wave device with a plurality of piezoelectric layers having at least one polarization inversion. The bulk acoustic wave device can include a first piezoelectric layer and a second piezoelectric layer over the first piezoelectric layer. The second piezoelectric layer can be formed by atomic layer deposition. The second piezoelectric layer can have an opposite polarization relative to the first piezoelectric layer. Related filters, multiplexers, packaged radio frequency modules, radio frequency front ends, wireless communication devices, and methods are disclosed.

The present application provides a resonator and a method of preparing same, and relates to the field of semiconductor technologies. The method includes: providing a device wafer, wherein the device wafer includes a first substrate and a piezoelectric layer, a bottom electrode, and a first mass loading layer formed in sequence on the first substrate; forming, on the bottom electrode, a sacrificial layer covering the first mass loading layer; forming a supporting layer on one side of the device wafer with the sacrificial layer; forming a second substrate on the supporting layer through a bonding process; removing the first substrate to expose the piezoelectric layer; forming a top electrode and a second mass loading layer in sequence on the piezoelectric layer; and releasing the sacrificial layer to form a cavity between the first mass loading layer and the supporting layer. Therefore, the resonator is correspondingly tuned by controlling a ratio of an area of the first mass loading layer in an effective working region of the resonator to an area of the second mass loading layer in the effective working region of the resonator, thereby manufacturing resonators with different resonant frequencies, effectively avoiding loss caused by tuning with an external element, and ensuring good performance of the resonator.

An acoustic resonator has a piezoelectric plate attached to the surface of the substrate except for a portion of the piezoelectric plate forming a diaphragm spanning a cavity in the substrate. An interdigital transducer (IDT) formed on the plate has interleaved fingers on the diaphragm with first parallel fingers extending from a first busbar and second parallel fingers extending from a second busbar of the IDT. An average center-to-center distance between adjacent interleaved fingers defines an IDT pitch. The IDT has a gap distance between the ends of the first plurality of parallel fingers and the second busbar, and between the ends of the second plurality of parallel fingers and the first busbar; and the gap distance is less than ⅔ times the IDT pitch.

An RF triplexer 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.

Techniques for improving Bulk Acoustic Wave (BAW) resonator structures are disclosed, including filters, oscillators and systems that may include such devices. First and second layers of piezoelectric material may be acoustically coupled with one another to have a piezoelectrically excitable resonance mode. The first layer of piezoelectric material may have a first piezoelectric axis orientation, and the second layer of piezoelectric material may have a second piezoelectric axis orientation that opposes the first piezoelectric axis orientation of the first layer of piezoelectric material. A top acoustic reflector including a first pair of top metal electrode layers may be electrically and acoustically coupled with the first layer of piezoelectric material to excite the piezoelectrically excitable main resonance mode at a resonant frequency.

A film bulk acoustic resonator (FBAR) structure includes, a bottom cap wafer, a piezoelectric layer disposed on the bottom cap wafer, the piezoelectric layer including lithium niobate or lithium tantalate, a bottom electrode disposed below the piezoelectric layer, and a top electrode disposed above the piezoelectric layer. Portions of the bottom electrode, the piezoelectric layer, and the top electrode that overlap with each other constitute a piezoelectric stack. The FBAR structure also includes a cavity disposed below the piezoelectric stack. A projection of the piezoelectric stack is located within the cavity.

A method for forming a film bulk acoustic resonator (FBAR) structure includes: sequentially forming a top electrode layer, a piezoelectric layer, and a bottom electrode layer on a first substrate; patterning the bottom electrode layer to form a bottom electrode; forming a dielectric layer on the bottom electrode; bonding a bonding substrate onto the dielectric layer; removing the first substrate; patterning the top electrode layer to form a top electrode; forming an opening in the bonding substrate; selectively removing a portion of the dielectric layer to form a cavity; and bonding a bottom cap wafer onto the bonding substrate to seal the cavity.