A surface acoustic wave (SAW) resonator device is provided. The SAW resonator device includes a first electrode positioned on an upper surface of a piezoelectric film. The first electrode may include a plurality of layers wherein a layer of the plurality of layers is a first heavy metal layer. The SAW resonator device may also include a first piezoelectric trench (PZT) positioned adjacent to the first electrode. The first PZT includes a recess in the piezoelectric film.

A surface acoustic wave resonator includes an IDT that is disposed on a quartz crystal substrate of Euler angles (1.51.5, 117142, ) and excites a surface acoustic wave resonant in an upper part of a stop-band of the IDT, and inter-electrode finger grooves that are acquired by depressing the substrate located between electrode fingers configuring the IDT. The wavelength of the surface acoustic wave, the depth of the inter-electrode finger grooves, the line occupancy ratio of the IDT, and the film thickness of the electrode fingers of the IDT are set in correspondence with one another.

A surface acoustic wave (SAW) device includes: a substrate; a finger portion of an interdigital transducer (IDT) electrode disposed on the substrate; a pad portion of the interdigital transducer electrode electrically connected to the finger portion; and a wiring electrode disposed on the pad portion. The wiring electrode includes a contact metal layer and an aluminum-based layer. The contact metal layer is disposed between the pad portion and the aluminum-based layer. The contact metal layer includes platinum, palladium, or gold.

An acoustic wave filter includes a first longitudinally coupled resonator including first and second IDT electrodes, and a second longitudinally coupled resonator including third and fourth IDT electrodes. Each IDT electrode includes a wide pitch electrode finger group and a narrow pitch electrode finger group. A number of electrode fingers in the wide pitch electrode finger group of the first IDT electrode is smaller than that in the wide pitch electrode finger group of the second IDT electrode by a percentage equal to or more than about 4.2% and equal to or less than about 23.5%. A number of the electrode fingers in the wide pitch electrode finger group of the IDT electrode third is smaller than that in the wide pitch electrode finger group of the fourth IDT electrode by a percentage equal to or more than about 9.5% and equal to or less than about 52.4%.

A surface acoustic wave (SAW) device includes a substrate; an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes formed on the substrate, wherein the interdigital electrodes includes central portions, end portions, and intermediate portions between the end portions and the lead-out portions, and a thickness of the interdigital electrodes at the end portions is greater than a thickness of the interdigital electrodes at the central portions and the intermediate portions, thereby forming protruding structures at the end portions of the interdigital electrodes; a protective layer formed on the protruding structures at the end portions of the interdigital electrodes; a first temperature compensation layer formed on the protective layer; a second temperature compensation layer formed on the first temperature compensation layer and on the central portions and the intermediate portions of the interdigital electrodes; and a passivation layer formed on the second temperature compensation layer.

An acoustic wave device has a multilayer piezoelectric substrate (MPS) structure and a multilayer interdigital transducer electrode (IDT). The multilayer piezoelectric substrate includes a piezoelectric layer over a support substrate. An additional (functional) layer can optionally be interposed between the piezoelectric layer and the support substrate, which can facilitate bonding between these layers and provide temperature compensation. The multilayer IDT is disposed over the piezoelectric layer and includes a first layer of a first material with higher density and a second layer of a different material with lower density. The interdigital transducer electrode also includes (mass loading) strips disposed over (e.g., adjacent, in contact with) the second layer, which advantageously facilitate suppression of transverse mode.

A filter device includes a series arm connecting input and output terminals. Parallel arms branch from the series arm to a ground terminal. The parallel arms include first and second parallel arms branching from portions of the series arm. The first and second parallel arm resonators are respectively provided in or on the first and second parallel arms. The parallel arm resonators each include an IDT electrode including electrode fingers. Each IDT electrode includes an overlap region. A number of pairs of electrode fingers of the IDT electrode in the first parallel arm resonator is greater than a number of pairs of electrode fingers of the IDT electrode in the second parallel arm resonator. An overlap width of the IDT electrode in the first parallel arm resonator is narrower than the overlap width of the IDT electrode in the second parallel arm resonator.

A filter device includes a piezoelectric substrate, a dielectric layer on the piezoelectric substrate, a first IDT electrode on the dielectric layer, a second IDT electrode positioned on the piezoelectric substrate in an area where the dielectric layer is not provided such that the first and second IDT electrodes are side by side in an acoustic wave propagation direction extending along a principal surface of the piezoelectric substrate, a first reflector on the dielectric layer and adjacent to the first IDT electrode on a side of the second IDT electrode, and a second reflector on the piezoelectric substrate and adjacent to the second IDT electrode on a side of the first IDT electrode. The dielectric layer includes an edge portion between the first and second reflectors in planar view seen from a stacking direction of the piezoelectric substrate and the dielectric layer.

A radio frequency multiplexer comprises a piezoelectric substrate, a first surface acoustic wave resonator including interdigital transducer electrodes disposed on the piezoelectric substrate and having a first metal layer formed of a first metal and a second metal layer disposed on the first metal layer and formed of a second metal having a higher density than the first metal, and a second surface acoustic wave resonator including interdigital transducer electrodes disposed on the piezoelectric substrate and having a first metal layer formed of the first metal, but lacking the second metal layer.