A bulk acoustic wave resonator includes a substrate; and a resonator including a first electrode, a piezoelectric layer, and a second electrode sequentially disposed on the substrate. Either one or both of the first electrode and the second electrode includes an alloy of molybdenum (Mo) and tantalum (Ta).

A bulk acoustic wave resonator includes a substrate, a first electrode and a second electrode disposed on the substrate, and a piezoelectric layer disposed between the first electrode and the second electrode. At least one of the first electrode and the second electrode includes an alloy of molybdenum and tantalum.

A method of forming a resonator includes forming top and bottom dielectric structures over a substrate. A piezoelectric layer is formed between the top and bottom dielectric structures. A bottom electrode is formed between the piezoelectric layer and the bottom dielectric structure, and a top electrode is formed between the piezoelectric layer and the top dielectric structure. A metal layer is formed over the top dielectric structure and is patterned, thereby forming a first contact pad making electrical contact to the top electrode, a second contact pad making electrical contact with the bottom electrode, and a mass bias located over the top dielectric structure.

An apparatus and method for making an acoustic filter package where the apparatus includes a base layer; a support layer disposed on the base layer; a piezoelectric structure disposed on the support layer; wherein the piezoelectric structure comprises: a piezoelectric layer; a top electrode on a top surface of the piezoelectric layer; a bottom electrode on a bottom surface of the piezoelectric layer; a contact pad coupled to the bottom electrode that extends through an opening in the piezoelectric layer and is coupled to the bottom electrode or the top electrode; and a corrosion resistant pad disposed on the contact pad; and a capping structure disposed on the piezoelectric structure.

An acoustic wave device includes a piezoelectric layer, an interdigital transducer, and a slow wave propagation overlay over a portion of the interdigital transducer. By providing electrode fingers of the interdigital transducer such that a portion of the width thereof is dependent on an electrode period, a desirable wave mode may be maintained in the acoustic wave device. Further, by varying a width of the slow wave propagation overlay based on the electrode period, the desirable wave mode may be further maintained.

An acoustic resonator comprises a first electrode and second electrode comprising a plurality of sides. At least one of the sides of the second electrode comprises a cantilevered portion. A piezoelectric layer is disposed between the first and second electrodes. A bridge disposed adjacent to one of the sides of the second electrode.

Bulk acoustic wave (BAW) resonators, and electrical filters that incorporate the BAW resonators, are described. Generally, the BAW resonators comprise a substrate comprising an acoustic reflector; a first electrode disposed over the acoustic reflector; a piezoelectric layer disposed over the first electrode, the piezoelectric layer comprising scandium-doped aluminum nitride (ASN); a diffusion barrier layer disposed over the piezoelectric layer; and a second electrode disposed over the diffusion barrier layer. The diffusion barrier layer configured to prevent diffusion of material of the first electrode into the piezoelectric layer.

A method of forming an integrated resonator apparatus includes depositing alternating dielectric layers of lower and higher acoustic impedance materials over a substrate. First and second resonator electrodes are formed over the alternating dielectric layers, with a piezoelectric layer located between the first and second resonator electrodes. A mass bias is formed over the first and second resonator electrodes. The mass bias, first and second electrodes, piezoelectric layer, and alternating dielectric layers may be encapsulated with a plastic mold fill.

A method of manufacturing a piezoelectric resonator unit that includes preparing a piezoelectric resonator having a piezoelectric element, a pair of excitation electrodes respectively disposed on a first main surface and a second main surface of the piezoelectric element so as to face each other with the piezoelectric element therebetween, and a pair of connection electrodes that are respectively electrically connected to the pair of excitation electrodes; electrically connecting the pair of connection electrodes to a pair of electrode pads on a third main surface of a base member using an electroconductive holding member so as to excitably hold the piezoelectric resonator on the third main surface of the base member; and attaching an electroconductive material, which is scattered from an electroconductive member, to a surface of the electroconductive holding member.

A quartz crystal resonator unit that includes a substrate, a lid, and an adhesive member that joins the substrate and the lid to each other to form an enclosure; a quartz crystal resonator disposed in the enclosure; and an adjustment member on the quartz crystal resonator and that includes a material whose volatilization amount per unit time and unit volume increases as humidity increases.