A method of manufacturing an integrated circuit. This method includes forming an epitaxial material comprising single crystal piezo material overlying a surface region of a substrate to a desired thickness and forming a trench region to form an exposed portion of the surface region through a pattern provided in the epitaxial material. Also, the method includes forming a topside landing pad metal and a first electrode member overlying a portion of the epitaxial material and a second electrode member overlying the topside landing pad metal. Furthermore, the method can include processing the backside of the substrate to form a backside trench region exposing a backside of the epitaxial material and the landing pad metal and forming a backside resonator metal material overlying the backside of the epitaxial material to couple to the second electrode member overlying the topside landing pad metal.

A method of forming a resonator structure can be provided by forming one or more template layers on a substrate, (a) epitaxially forming an AlScN layer on the template layer to a first thickness, (b) epitaxially forming an AlGaN interlayer on the AlScN layer to a second thickness that is substantially less than the first thickness, and repeating operations (a) and (b) until a total thickness of all AlScN layers and AlGaN interlayers provides a target thickness for a single crystal AlScN/AlGaN superlattice resonator structure on the template layer.

The present disclosure relates to a bulk acoustic wave (BAW) resonator capable of reducing electrical losses for high frequency applications without suffering extra material losses, thereby producing high-performance high frequency BAW filters, and a fabricating process to provide such BAW resonator. The disclosed BAW resonator includes a conductive reflector, a dielectric layer over the conductive reflector, a seed layer over the dielectric layer, a bottom electrode over the seed layer, a connection structure electrically connecting the bottom electrode and the conductive reflector, a piezoelectric film over the bottom electrode, and a top electrode over the piezoelectric film. Herein, a combination of the bottom electrode, the seed layer, and the dielectric layer only partially covers a top surface of the bottom reflector. At least 80% of metal grains in the bottom electrode are oriented within 3 degrees towards a thermodynamically stable orientation of metal materials in the bottom electrode.

A method and structure for a transfer process for an acoustic resonator device. In an example, a bulk acoustic wave resonator (BAWR) with an air reflection cavity is formed. A piezoelectric thin film is grown on a crystalline substrate. Patterned electrodes are deposited on the surface of the piezoelectric film. An etched sacrificial layer is deposited over the electrodes and a planarized support layer is deposited over the sacrificial layer. The device can include temperature compensation layers (TCL) that improve the device TCF. These layers can be thin layers of oxide type materials and can be configured between the top electrode and the piezoelectric layer, between the bottom electrode and the piezoelectric layer, between two or more piezoelectric layers, and any combination thereof. In an example, the TCLs can be configured from thick passivation layers overlying the top electrode and/or underlying the bottom electrode.

An apparatus includes a semiconductor substrate, a bulk acoustic wave (BAW) resonator, and a coating or protrusion structures. The BAW resonator is on a first side of the semiconductor substrate. The coating and/or the protrusion structures are on a second side of the semiconductor substrate. The coating has a lower Young's modulus than the semiconductor substrate. The protrusion structures have uniform dimensions.

A method for forming a BAW device. The BAW device includes forming a dielectric layer over a reflector structure, forming an electrode seed material layer over the dielectric layer, forming an electrode material layer over the electrode seed material layer, patterning the electrode material layer to form an electrode layer and to expose the reflector structure, and forming a connection layer in contact with the electrode layer and the reflector structure.

A piezoelectric resonator can include a substrate and a piezoelectric aluminum nitride layer on the substrate, where the piezoelectric aluminum nitride layer is doped with a dopant selected from the group consisting of Si, Mg, Ge, C, Sc and/or Fe at a respective level sufficient to induce a stress in the piezoelectric aluminum nitride layer in a range between about 150 MPa compressive stress and about 300 MPa tensile stress.

In an acoustic mirror of a bulk-acoustic wave (BAW) device, acoustic energy is reflected at interfaces of layers having different acoustic impedances, and the wavelengths of the acoustic energy reflected at each layer depends on the layer thickness. The acoustic mirror comprises a patterned layer including a first region of a first material and a second region of the first material separated by a second material to reduce an effective thickness of the layer for acoustic reflection. As operating frequencies in wireless devices increase, current manufacturing practices may be unable to produce the correspondingly thinner layers of the acoustic mirror. Thus, the BAW device described herein can be employed to provide a reduced effective thickness for acoustic reflection with layers having an actual thickness that can be formed by existing manufacturing practices. In some examples, the first material and the second material have different acoustic impedances.

An acoustic wave device assembly is disclosed. The 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 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, a second interdigital transducer electrode that is in contact with the second piezoelectric layer, and a third solid acoustic mirror over the second interdigital transducer electrode. The first acoustic wave device and the second acoustic wave device being stacked on one another. The acoustic wave device assembly can include a spacer assembly that is disposed over the first piezoelectric layer.

An acoustic wave device assembly is disclosed. The 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 embedded in the piezoelectric layer. The 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.