An elastic wave device includes a piezoelectric substrate, an IDT electrode including a first electrode layer located on the piezoelectric substrate and including one of Mo and W as a main component and a second electrode layer laminated on the first electrode layer and including Cu as a main component, and a dielectric film located on the piezoelectric substrate and covering the IDT electrode. The piezoelectric substrate is made of lithium niobate. The dielectric film is made of silicon oxide. The elastic wave device utilizes Rayleigh waves propagating along the piezoelectric substrate.

An acoustic wave device comprises a piezoelectric material and a second material disposed on the piezoelectric material and having a temperature coefficient of frequency of a sign opposite a sign of a temperature coefficient of frequency of the piezoelectric material, the second material including one or more of Si.sub.1-x-yTi.sub.xP.sub.yO.sub.2-zF.sub.z (x,y,z<0.1), Si.sub.1-x-yGe.sub.xP.sub.yO.sub.2-zF.sub.z, Si.sub.1-x-yB.sub.xP.sub.yO.sub.2-zF.sub.z (x=y<0.04), Si.sub.1-3xZn.sub.xP.sub.2xO.sub.2-yF.sub.y, Si.sub.1-xP.sub.xO.sub.2-yF.sub.y, Si.sub.1-2yGa.sub.xP.sub.xO.sub.4, Si.sub.1-2yGa.sub.y-xB.sub.xP.sub.yO.sub.4, Si.sub.1-2yGa.sub.y-xB.sub.xP.sub.yO.sub.4-zF.sub.z, TiNb.sub.10O.sub.29, Si.sub.1-xTi.sub.xO.sub.2-yF.sub.y, Si.sub.1-x-yTi.sub.xP.sub.yO.sub.2, Si.sub.1-xB.sub.xO.sub.2-yF.sub.y, Si.sub.1-x-yB.sub.xP.sub.yO.sub.2, GeO.sub.2, GeO.sub.2-yF.sub.y, Si.sub.1-xGe.sub.xO.sub.2, Si.sub.1-xGe.sub.xO.sub.2-yF.sub.y, Si.sub.1-x-yGe.sub.xP.sub.yO.sub.2, ZnP.sub.2O.sub.6, Si.sub.1-3xZn.sub.xP.sub.2xO.sub.2, Ge.sub.1-3xZn.sub.xP.sub.2xO.sub.2, TeO.sub.x, Si.sub.1-xTe.sub.xO.sub.2+y, Ge.sub.1-xTe.sub.xO.sub.2+y, Si.sub.1-3x-yGe.sub.yZn.sub.xP.sub.2xO.sub.2, Si.sub.1-xP.sub.xO.sub.2-xN.sub.x, Si—O—C, Si.sub.1-2yAl.sub.xP.sub.xO.sub.4, or BeF.sub.2.

An elastic wave device includes a spacer layer on or above a support substrate and outside a piezoelectric film as seen in a plan view from a thickness direction of the support substrate. A cover layer is disposed on the spacer layer. A through electrode extends through the spacer layer and the cover layer and is electrically connected to the wiring electrode. The wiring electrode includes a first section overlapping the through electrode as seen in the plan view from the thickness direction, a second section overlapping the piezoelectric film as seen in the plan view from the thickness direction, and a step portion defining a step in the thickness direction between the first section and the second section. The spacer layer includes an end portion embedded in the cover layer.

Aspects of this disclosure relate to an acoustic wave device with transverse mode suppression. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a multi-layer mass loading strip. The mass loading strip has a density that is higher than a density of the temperature compensation layer. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. The mass loading strip can include a first layer for adhesion and a second layer for mass loading. The mass loading strip can suppress a transverse mode.

A bulk acoustic resonator operable in a bulk acoustic mode includes a resonator body mounted to a separate carrier that is not part of the resonator body. The resonator body includes a piezoelectric layer, a device layer, and a top conductive layer on the piezoelectric layer opposite the device layer. The piezoelectric layer is a single crystal of LiNbO.sub.3 cut at an angle of 130°±30°. A surface of the device layer opposite the piezoelectric layer is for mounting the resonator body to the carrier.

An acoustic wave device that has a better TCF and can improve a resonator Q or impedance ratio is provided. The acoustic wave device includes a substrate 11 containing 70 mass % or greater of silicon dioxide (SiO.sub.2), a piezoelectric thin film 12 including LiTaO.sub.3 crystal or LiNbO.sub.3 crystal and disposed on the substrate 11, and an interdigital transducer electrode 13 disposed in contact with the piezoelectric thin film 12.

In at least one embodiment, the SAW device comprises a carrier substrate (1), a piezoelectric thin-film (2) on the carrier substrate, an interdigital electrode structure (3) on the piezoelectric thin-film and a layer stack (4) of waveguide layers. The layer stack is arranged between the carrier substrate and the piezoelectric thin-film. The layer stack comprises a first waveguide layer (41) and second waveguide layer (42), wherein a sound velocity in the first waveguide layer is at least 1.5 times as great as in the second waveguide layer. The device may comprise a temperature compensating layer (5) and a trap rich layer (6) between the layer stack and the carrier substrate.

A SAW resonator with reduced spurious modes is provided. The resonator comprises a (111) silicon carrier substrate (CS), an electrode structure (ES) and a piezoelectric layer (PIL). The carrier substrate has a crystal orientation with the Euler angles (−45°±10°; −54°±10°; 60°±30°) and the piezoelectric layer comprises LiTaO.sub.3 and has a crystal orientation with the Euler angles (0°; 56°±8°; 0°). There may be intermediate layers (IL1, IL2) of SiO.sub.2 and amorphous or polycrystalline materials. In addition a silicon nitride layer is provided as passivation (PAL). Electrodes are made of aluminum. Thicknesses of all layers are selected in particular ranges to optimize SAW behaviour.

At least three acoustic filters circuits FC are arranged on a single chip CH. At least two of them are electrically connected already on the chip for multiplexing. This reduces space consumption and leads to smaller device size.

The present invention relates to a heterostructure, in particular, a piezoelectric structure, comprising a cover layer, in particular, a layer of piezoelectric material, the material of the cover layer having a first coefficient of thermal expansion, assembled to a support substrate, the support substrate having a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion, at an interface wherein the cover layer comprises at least a recess extending from the interface into the cover layer, and its method of fabrication.