An acoustic wave device includes a support substrate, a piezoelectric layer on the support substrate, functional electrodes on the piezoelectric layer, and first and second electrode films positioned on the piezoelectric layer to face each other and having different potentials from each other. A thickness of the piezoelectric layer in at least a portion of a first region overlapping the first electrode film in plan view is different from a thickness of the piezoelectric layer in at least a portion of a second region not overlapping the first electrode film in plan view.

A method for fabricating a multi-layer resonator assembly includes sequentially fabricating a plurality of vertically-stacked resonator layers including, for each resonator layer of the plurality of resonator layers, depositing a dielectric layer, forming at least one film bulk acoustic resonator (FBAR) cavity in the deposited dielectric layer, filling each FBAR cavity of the at least one FBAR cavity with a sacrificial material block, and depositing a FBAR material stack over the at least one FBAR cavity. The deposited FBAR material stack is in contact with the sacrificial material block and the dielectric layer. The method further includes removing the sacrificial material block from the at least one FBAR cavity for each resonator layer of the plurality of resonator layers subsequent to sequentially fabricating the plurality of resonator layers.

A bulk acoustic wave device includes a first electrode, a second electrode, a first piezoelectric layer between the first electrode and the second electrode, a third electrode, and a second piezoelectric layer. The second piezoelectric layer is between the second electrode and the third electrode.

A bulk acoustic wave device includes a first resonator having a first pair of electrodes and a first piezoelectric layer. The first pair of electrodes has a first top electrode and a first bottom electrode. The first piezoelectric layer is positioned between the first top electrode and a first bottom electrode. The device includes a second resonator having a second pair of electrodes and a second piezoelectric layer. The second pair of electrodes has a second top electrode and a second bottom electrode. The second piezoelectric layer is positioned between the second top electrode and a second bottom electrode. The first and second piezoelectric layers are positioned between the first bottom electrode and the second top electrode.

An acoustic wave device includes a support including a support substrate with a thickness direction in a first direction, a piezoelectric layer on the support, and resonators each including a functional electrode provided to the piezoelectric layer. The support is provided with a hollow portion at a position overlapping at least a portion of each of the resonators in plan view in the first direction. The resonators include a first resonator and a second resonator adjacent to each other. A through hole reaching the hollow portion is provided to the piezoelectric layer between the first resonator and the second resonator.

An acoustic wave device includes a support including a support substrate with a thickness in a first direction, a piezoelectric layer on the support in the first direction on the support, and resonators each including a functional electrode on the piezoelectric layer in the first direction on the piezoelectric layer. The support includes space portions therein at positions where the functional electrodes at least partially overlap in a planar view in the first direction. The support includes a lead portion communicating with at least one of the space portions in a planar view in the first direction, at a position that does not overlap the space portion. At least one lead portion communicates with at least two of the space portions. The piezoelectric layer includes a through-hole penetrating the piezoelectric layer at a position overlapping the lead portion in a planar view in the first direction.

A radio frequency ladder filter comprises a plurality of series bulk acoustic wave (BAW) resonators electrically connected in series between an input and an output, at least one BAW resonator connected between a node between adjacent ones of the plurality of series BAW resonators and ground, at least one shunt resonator element including an inductor and a capacitor in series and electrically coupled to ground between the input and a first of the plurality of series resonators, and at least one last shunt resonator element including an inductor and a capacitor in series and electrically coupled to ground between the output and a last of the plurality of series resonators.

An acoustic wave device, a radio frequency filter and an electronics module are provided. The acoustic wave device, comprises a layer of piezoelectric material, a pair of interdigital transducer electrodes disposed on an upper surface of the layer of piezoelectric material, each interdigital transducer electrode including a bus bar and a plurality of electrode fingers extending from the bus bar through a central region of the interdigital transducer electrode towards an edge region of the interdigital transducer electrode, each of the plurality of electrode fingers having a width in a direction perpendicular to the extension of the electrode fingers that is smaller in the edge regions than in the central regions, and trench portions located in the upper surface of the layer of piezoelectric material, the trench portions overlapping with the edge regions of the interdigital transducer electrodes. The acoustic wave device provides effective suppression of transverse modes.

An apparatus includes a die, a bonding layer, and a film. The die includes a semiconductor substrate, a metallization structure on the semiconductor substrate, and a dielectric material around at least a part of the metallization structure. The bonding layer is on the metallization structure. The film is attached on the bonding layer. The film includes a piezoelectric material.

An acoustic wave device includes a support including a support substrate with a thickness in a first direction, a piezoelectric layer on the support in the first direction on the support, and resonators each including a functional electrode on the piezoelectric layer in the first direction on the piezoelectric layer. The support includes space portions therein at positions where the functional electrodes at least partially overlap in a planar view in the first direction. The support includes a lead portion communicating with at least one of the space portions in a planar view in the first direction, at a position that does not overlap the space portion. At least one lead portion communicates with at least two of the space portions. The piezoelectric layer includes a through-hole penetrating the piezoelectric layer at a position overlapping the lead portion in a planar view in the first direction.