An acoustic wave device includes a piezoelectric substrate made of LiNbO.sub.3, and a dielectric film provided on the piezoelectric substrate to cover first and second IDT electrodes on the piezoelectric substrate. The first and second IDT electrodes include main electrode layers. When wave lengths determined by electrode finger pitches of the first and second IDT electrodes are λ.sub.1 and λ.sub.2, respectively, the average value thereof is λ.sub.0, λ.sub.1/λ.sub.0=1+X, and λ.sub.2/λ.sub.0=1−X, a relationship of 0.05≤X≤0.65 is satisfied. The wavelength λ.sub.1 is the longest, and the wavelength λ.sub.2 is the shortest. In Euler angles (φ, θ, ψ) of the piezoelectric substrate, φ is 0°±5°, ψ is 0°±10°, and θ satisfies Expression 1, wherein a relationship of B.sub.1<T×r≤0.10λ.sub.0 and B.sub.2<T×r≤0.10λ.sub.0 are satisfied.

An acoustic wave device includes a substrate, an interdigital transducer electrode including electrode fingers on a main surface of the substrate, and a protection film covering the main surface of the substrate, and side surfaces and upper surfaces of the electrode fingers. The protection film includes a portion covering the main surface of the substrate, an intermediate portion between two of the electrode fingers adjacent to each other, and a vicinity portion of the electrode fingers. The intermediate portion is thicker than the vicinity portion.

Methods of manufacturing an acoustic wave device are disclosed. An anti-reflection layer can be formed over a conductive layer that is over a piezoelectric layer. The conductive layer can include aluminum, for example. The anti-reflection layer can remain distinct from the conductive layer after a heating process. A photolithography process can pattern an interdigital transducer of the acoustic wave device from one or more interdigital transducer electrode layers that include the conductive layer. The anti-reflection layer can reduce reflection from the conductive layer during the photolithography process.

A filter includes: a series-arm resonator; and a parallel-arm resonator. The series-arm resonator and the parallel-arm resonator each include: an interdigital transducer (IDT) electrode formed on a substrate and including a plurality of electrode fingers; and a protective film. The protective film included in the parallel-arm resonator is thinner than the protective film included in the series-arm resonator. The parallel-arm resonator has a first fractional bandwidth ((the higher-order resonance frequency−the resonant frequency)/the resonant frequency) greater than the first fractional bandwidth of the series-arm resonator. The parallel-arm resonator has a second fractional bandwidth ((the higher-order antiresonant frequency−the antiresonant frequency)/the antiresonant frequency) greater than the second fractional bandwidth of the series-arm resonator.

A surface acoustic wave (SAW) filter package structure includes a dielectric substrate having a dielectric layer, a first patterned conductive layer, a second patterned conductive layer, and a conductive connection layer. The conductive connection layer is electrically connected between the first patterned conductive layer and the second patterned conductive layer, which are disposed at opposite sides of the dielectric layer. The second patterned conductive layer has a finger electrode portion. An active surface of a chip is faced toward the finger electrode portion. A polymer sealing frame is disposed between the chip and the dielectric substrate and surrounds the periphery of the chip to form a chamber together with the chip and the dielectric substrate. The mold sealing layer is disposed on the dielectric substrate and covers the chip and the polymer sealing frame. A manufacturing method of the SAW filter package structure is also disclosed.

An acoustic wave device includes a piezoelectric layer made of lithium niobate or lithium tantalate, and first and second electrodes opposed to each other in a direction that intersects with a thickness direction of the piezoelectric layer. The first and second electrodes are adjacent electrodes, and, when a thickness of the piezoelectric layer is d and a distance between centers of the first and second electrodes is p, d/p is less than or equal to about 0.5.

An acoustic wave device includes a piezoelectric layer, at least one pair of electrodes adjacent to each other, and an additional film. The piezoelectric layer is made of lithium niobate or lithium tantalate, and includes first and second opposing principal surfaces. The at least one pair of electrodes is located on the first principal surface of the piezoelectric layer. The additional film is located on the piezoelectric layer or either one or both of the electrodes so as to overlap, in plan view, either one or both of areas in which the electrodes are located and an area between the electrodes. When d represents a thickness of the piezoelectric layer and p represents a center-to-center distance between the electrodes, d/p is equal to or less than about 0.5.

An acoustic wave device includes a piezoelectric substrate and an electrode on the piezoelectric substrate and including first and second layers. The first layer includes Al and Cu. The second layer is on a side opposite to a piezoelectric substrate side of the first layer and includes Al. The first layer includes an Al crystal and at least a portion of CuAl.sub.2 crystal grains that are provided in a direction orthogonal or substantially orthogonal to a thickness direction of the piezoelectric substrate. In the electrode, the CuAl.sub.2 crystal grains do not extend to the main surface of the second layer on a side opposite to a first layer side.

An acoustic wave device is disclosed. The acoustic wave device includes a piezoelectric layer, an interdigital transducer electrode positioned over the piezoelectric layer, and an anti-refection layer over a conductive layer of the interdigital transducer electrode. The conductive layer can include aluminum, for example. The anti-reflection layer can include silicon. The anti-reflection layer can be free from a material of the interdigital transducer electrode. The acoustic wave device can further include a temperature compensation layer positioned over the anti-reflection layer in certain embodiments.

Certain aspects of the present disclosure provide a surface acoustic wave (SAW) resonator with piston mode design and electrostatic discharge (ESD) protections. An example electroacoustic device generally includes a piezoelectric material and a first electrode structure disposed above the piezoelectric material. The first electrode structure comprises first electrode fingers arranged within an active region having a first region and a second region. At least one of the first electrode fingers has at least one of a different width or a different height in the first region than in the second region, and the first electrode fingers comprise a first electrode finger that has a width or height in the second region that is less than a corresponding width or height of the at least one of the first electrode fingers in the second region.