There are disclosed acoustic resonators and radio frequency filter devices. An acoustic resonator includes a piezoelectric plate having a front surface. A conductor pattern is formed on the front surface, the conductor pattern including interdigital transducers (IDTs) of one or more pairs of sub-resonators, each pair consisting of two sub-resonators. The two sub-resonators of each pair of sub-resonators are positioned symmetrically about a central axis.

An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

A surface acoustic wave (SAW) filter device includes: a first layer disposed on a substrate; an inter-digital transducer (IDT) electrode layer disposed on the first layer; a second layer covering the IDT electrode layer and the first layer; and an overlay layer covering the second layer, wherein the first layer includes any one or any combination of any two or more of a metal layer, a metal oxide layer, and an oxide layer.

In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a C plane on a Z axis side of the piezoelectric thin film, the C plane on the Z axis side of the piezoelectric thin film is etched. Thus, Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the Z planes of the piezoelectric thin film in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film.

The present invention relates to a surface acoustic wave device package and a method of manufacturing the same, and more specifically, to a method of manufacturing a miniaturized surface acoustic wave device package.

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 surface acoustic wave resonator includes first and second surface acoustic wave resonator connected in series, and a third surface acoustic wave resonator connected in series with the second surface acoustic wave resonator. Each of the first to third surface acoustic wave resonators includes a pair of comb-shaped electrodes in which electrode fingers of one of the comb-shaped electrodes and electrode fingers of the other one of the comb-shaped electrodes are alternately arranged. The second surface acoustic wave resonator has a lower ratio of a width of the electrode fingers to a pitch between the electrode fingers than the first and third surface acoustic wave resonators.

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.

An SAW resonator includes a piezoelectric substrate, an IDT electrode, and a pair of reflectors. The IDT electrode includes pluralities of electrode fingers which are aligned on the piezoelectric substrate in a direction of propagation of a SAW. The pair of reflectors are located on the two sides of the pluralities of electrode fingers on the piezoelectric substrate in the direction of propagation. The IDT electrode includes a plurality of areas which includes pluralities of electrode fingers distributed to them and have different resonance frequencies from each other. The plurality of areas include at least three areas. The second highest resonance frequency among all areas is lower than an intermediate value between the lowest resonance frequency among all areas and the highest resonance frequency among all areas.

An acoustic wave device includes a piezoelectric layer, and at least one pair of comb-shaped electrodes provided on the piezoelectric layer, each of the comb-shaped electrodes including electrode fingers each having a first layer and a second layer provided on the first layer, the first layer being a titanium nitride layer with a thickness greater than 50 nm, the second layer being a metal layer.