An acoustic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate and includes a main electrode layer. In the IDT electrode, a central region, first and second low acoustic velocity regions and first and second high acoustic velocity regions are disposed in this order. A duty ratio in the first low acoustic velocity region of first electrode fingers and the second low acoustic velocity region of second electrode fingers is larger than a duty ratio in the central region. The main electrode layer includes any one of Au, Pt, Ta, Cu, Ni, and Mo as a main component.

A surface acoustic wave resonator structure and a method of forming the resonator structure and a filter are provided. The resonator structure includes: a piezoelectric substrate; an interdigital transducer including a first interdigital electrode structure and a second interdigital electrode structure, wherein the first interdigital electrode structure comprises first interdigital electrodes and a first interdigital electrode lead-out part connected to each other, the second interdigital electrode structure comprises second interdigital electrodes and a second interdigital electrode lead-out part connected to each other, the first interdigital electrodes and the second interdigital electrodes extend along a first direction and are alternately arranged in a second direction; a temperature compensation layer, disposed on a side of the interdigital transducer away from the piezoelectric substrate; and a first protection layer disposed between the interdigital transducer and the temperature compensation layer and configured to protect the interdigital transducer from being oxidized.

According to various embodiments, there is provided a resonator device that includes a first interdigital transducer and a second interdigital transducer that is electrically connected to the first interdigital transducer. Both the first interdigital transducer and the second interdigital transducer are configured to resonate at a common frequency. At least one of an electrode width and an electrode pitch of the first interdigital transducer is different from the respective electrode width and/or electrode pitch of the second interdigital transducer such that spurious peaks of the resonator device are lower in amplitude as compared to spurious peaks of each of the first interdigital transducer and the second interdigital transducer.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate. The IDT electrode includes a first comb-shaped electrode including first electrode fingers and a second comb-shaped electrode including second electrode fingers. The IDT electrode includes a first portion in which a main electrode layer includes a first metal and a second portion in which a main electrode layer includes a second metal. The first electrode fingers and the second comb-shaped electrode include first facing portions facing each other with a gap in between, and the second electrode fingers and the first comb-shaped electrode include second facing portions facing each other with a gap in between. At least one of the first facing portions and second facing portions is the second portion, and a portion of the IDT electrode other than the second portion is the first portion.

In an acoustic wave device, a piezoelectric layer is directly or indirectly laminated on a support substrate, an IDT electrode is provided on a first main surface of the piezoelectric layer, and F(x)=Ax.sup.2+Bx+C, where F(x) is equal to or less than about 10, when a thickness of a metal film of the IDT electrode normalized by a wavelength λ is defined as te, a thickness of the piezoelectric layer normalized by the wavelength λ is defined as tp, an equation of te/tp=x is satisfied, an average density obtained by normalizing a total mass of the metal film by the thickness te of the metal film is defined as y[g/cm.sup.3], and

A=1.0392y.sup.2+8.4182y−45.223;

B=0.0334y.sup.2−11.363y+28.984; and

C=19.

A method of manufacturing an acoustic wave device includes forming a multilayer piezoelectric substrate by forming a piezoelectric layer and forming a support substrate below the piezoelectric layer. The method also includes forming an interdigital transducer electrode including forming a first layer disposed over the piezoelectric layer, forming a second layer disposed over the first layer, the second layer being of a less dense material than the first layer, forming a third layer disposed over the second layer. The method also includes etching the third layer to form a pair of strips extending over one or more fingers of the interdigital transducer electrode and having a density that suppresses a transverse mode of the acoustic wave device.

A surface acoustic wave package has a piezoelectric layer over a substrate and a thermally conductive structure attached to the substrate. The outer boundary of the piezoelectric layer is removed (e.g., etched) so that a resulting outer edge of the piezoelectric layer is spaced inward of an inner edge of the thermally conductive structure. The piezoelectric layer does not contact the thermally conductive structure to inhibit damage to the piezoelectric layer due to a stress differential between the substrate and the thermally conductive structure during a packaging process.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer positioned partially between the piezoelectric layer and the interdigital transducer electrode. The dielectric layer is positioned in an area under a first portion of the interdigital transducer electrode. An area under a second portion different from the first portion is free from the dielectric layer.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer positioned partially between the piezoelectric layer and the interdigital transducer electrode. The interdigital transducer electrode includes an active region that has a center region and an edge region, a bus bar, and a gap region between the active region and the bus bar. At least a portion of the center region is in direct contact with the piezoelectric layer.

An apparatus is disclosed for a surface-acoustic-wave filter using lithium niobate (LiNbO.sub.3). In an example aspect, the apparatus includes at least one surface-acoustic-wave filter including an electrode structure, a substrate layer, and a piezoelectric layer disposed between the electrode structure and the substrate layer. The piezoelectric layer includes lithium niobate material configured to enable propagation of an acoustic wave across its planar surface in a direction along a first filter axis. A second filter axis is along the planar surface and perpendicular to the first filter axis. A third filter axis is normal to the planar surface. An orientation of the first, second, and third filter axes is relative to a crystalline structure of the lithium niobate material as defined by Euler angles λ, μ, and θ. A value of μ has a range approximately from −70° to −55° or at least one symmetrical equivalent.