A surface acoustic wave device includes a piezoelectric substrate, a supportive layer, a cover layer and a pillar bump. The supportive layer is disposed on the piezoelectric substrate and around a transducer, the cover layer covers the supportive layer, and the pillar bump is located in a lower via hole of the supportive layer and an upper via hole of the cover layer. The upper via hole has a lateral opening located on a lateral surface of the cover layer, and the pillar bump in the cover layer protrudes from the lateral surface of the cover layer via the lateral opening.

A transducer structure for a surface acoustic wave device, comprising a pair of inter-digitated comb electrodes, wherein the pair of inter-digitated comb electrodes comprises neighboring electrode means belonging to different comb electrodes and having a pitch p being defined as the edge-to-edge electrode means distance between two neighboring electrode means, the pitch p satisfying the Bragg condition; characterized in that the pair of inter-digitated comb electrodes comprises at least one region in which two or more neighboring electrode means belong to the same comb electrode while having an edge-to-edge distance to each other corresponding to the pitch p. The present disclosure relates also to a surface acoustic wave filter device.

A surface acoustic wave device includes a piezoelectric substrate formed from a Ca.sub.3Ta(Ga.sub.1-xAl.sub.x).sub.3Si.sub.2O.sub.14 single crystal, and an interdigital electrode formed on the surface of the piezoelectric substrate and formed from Al. The interdigital electrode is configured to generate a Love-wave-type SH wave on the surface of the piezoelectric substrate. A normalized film thickness obtained by dividing the film thickness of the interdigital electrode by the wavelength of the Love-wave-type SH wave is 0.16 or less.

An acoustic wave device includes a silicon oxide film, a piezoelectric body, and an interdigital transducer electrode laminated on a support substrate made of silicon. Where a wave length that is determined by an electrode finger pitch of the interdigital transducer electrode is λ, a thickness of the support substrate is greater than or equal to about 3λ. An acoustic velocity of the first higher mode that propagates through the piezoelectric body is an acoustic velocity V.sub.si=(V.sub.1).sup.1/2 of bulk waves that propagate in the support substrate, which is determined by V.sub.1 out of solutions V.sub.1, V.sub.2, and V.sub.3 of x derived from the mathematical expression Ax.sup.3+Bx.sup.2+Cx+D=0, or higher than V.sub.si.

An acoustic wave device, a radio frequency filter and an electronics module are provided. The acoustic wave device comprises a piezoelectric substrate, a temperature compensation layer disposed on the piezoelectric substrate, and an interdigital transducer embedded within the temperature compensation layer and spatially separated from the piezoelectric substrate. The interdigital transducer is configured to generate an acoustic wave in response to an electrical signal. A passivation layer is disposed on the temperature compensation layer. The acoustic wave device can be used in wide passband applications, and has an excellent temperature coefficient, small size, and a clean response.

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.

In an elastic wave device, an IDT electrode is provided on a piezoelectric substrate and a first silicon oxide film covers the IDT electrode. A high-acoustic-velocity dielectric film covers the first silicon oxide film. A second silicon oxide film is provided on the high-acoustic-velocity dielectric film. The piezoelectric substrate is made of lithium niobate. The high-acoustic-velocity dielectric film propagates longitudinal waves at an acoustic velocity higher than an acoustic velocity of longitudinal waves propagating through the first silicon oxide film. The high-acoustic-velocity dielectric film is provided at a distance of about (t1+t2)×0.42 or less from a first main surface of the piezoelectric substrate in a thickness direction of the piezoelectric substrate.

A surface acoustic wave filter includes series and parallel arm resonance sections. The series arm resonance section is in a series arm. The parallel arm resonance section is in a parallel arm. The series arm resonance section includes one or more surface acoustic wave devices. Each surface acoustic wave device includes a first resonator group and a second resonator group. The first and second resonator groups are connected in parallel and include surface acoustic wave resonators. The first resonator group includes at least one surface acoustic wave resonator. The second resonator group includes a greater number of surface acoustic wave resonators than the at least one surface acoustic wave resonator in the first resonator group. The resonant frequency of the surface acoustic wave resonator in the first resonator group is higher than the resonant frequency of the surface acoustic wave resonators in the second resonator group.

A high frequency module includes a mounting substrate, an acoustic wave filter, a protection member, a resin layer, and a shield layer. The acoustic wave filter is mounted on a first main surface of the mounting substrate. The protection member is disposed on a main surface of the acoustic wave filter that is far from the mounting substrate. The resin layer is disposed on the first main surface of the mounting substrate and covers an outer peripheral surface of the acoustic wave filter and an outer peripheral surface of the protection member. The shield layer covers the resin layer and the protection member. The protection member is in contact with both the acoustic wave filter and the shield layer. The acoustic wave filter includes a piezoelectric substrate. A main surface of the piezoelectric substrate that is far from the mounting substrate is in contact with the protection member.

An acoustic wave filter includes a substrate and a piezoelectric layer over the substrate. First acoustic wave resonators are disposed over the piezoelectric layer and arranged in series along a first branch, and second acoustic wave resonators are disposed over the piezoelectric layer, arranged in parallel, and connected to the first branch and to ground. The first and second acoustic wave resonators include an interdigital transducer electrode interposed between a pair of reflectors. A layer of negative temperature coefficient of frequency dielectric material is disposed over one or more of the second plurality of acoustic wave resonators to control the temperature coefficient of frequency and improve temperature stability of the acoustic wave filter.