A surface acoustic wave device includes: comb-shaped electrodes each including electrode fingers and dummy electrode fingers; and additional films located to cover gaps between tips of the electrode fingers of one of the comb-shaped electrodes and tips of the dummy electrode fingers of the other, wherein each of the additional films overlap with at least one of the electrode fingers and the dummy electrode fingers located lateral to the corresponding gap in a first direction in which the electrode fingers extend or in a second direction intersecting with the first direction, and a distance G of the gap is 0<G1.0 and a film thickness h of the additional films is 0<h/(0.146G+0.694076)2/1 where is a wavelength of an acoustic wave, 1 is a density of a material of the additional films, and 2 is a density of aluminum oxide.

An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO.sub.3 substrate. When Euler Angles of the LiNbO.sub.3 substrate are within a range of about 0??5?, within a range of about ??1.5?, within a range of about 0??10?, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and ? of the Euler Angles satisfy ?=?0.05?/(T/r?0.04)+31.35?.

In an acoustic wave device, a region where first and second electrode fingers overlap each other is an intersection region including a central region and edge regions facing each other and interposing the central region in a first direction. Each of busbars in the IDT electrode includes reflector busbars in reflector cavities along the second direction. VaVb when an acoustic velocity in the central region is Va and an acoustic velocity in a first cavity containing region is Vb, in a portion where the IDT electrode is provided. VcVd when an acoustic velocity in the extended central region is Vc and an acoustic velocity in third and fourth cavity containing regions is Vd, in a portion where each of the reflectors is provided. (Vb/Va)(Vd/Vc) in the portion where the IDT electrode is provided and in a portion where at least one reflector is provided.

Aspects of this disclosure relate to a method for making an acoustic wave resonator with hyperbolic mode suppression. The acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can be a conductive strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. A layer of the mass loading strip can have a density that is at least as high as a density of a material of the interdigital transducer electrode. The material of the interdigital transducer can impact acoustic properties of the acoustic wave resonator.

An acoustic wave device includes acoustic wave resonators each including a piezoelectric substrate including a piezoelectric body layer, and an IDT electrode on the piezoelectric substrate and including electrode fingers. At least one of the acoustic wave resonators is an excitation angle change resonator, in which, the piezoelectric body layer includes a propagation axis and the electrode fingers are curved. In the excitation angle change resonator, an excitation direction of an acoustic wave in a portion of one of the electrode fingers is one of first, second, or third directions. An excitation angle of the excitation angle change resonator is not uniform in the IDT electrode.

The present invention provides a surface acoustic wave filter with a mass addition film formed on a plurality of electrodes. The surface acoustic wave filter includes a substrate on which a support substrate, an energy confinement layer, and a piezoelectric layer are sequentially stacked; first and second bus bars extended in a first direction on the substrate and spaced apart from each other in a second direction perpendicular to the first direction; a plurality of IDT electrodes alternately extended from the first and second bus bars in the second direction and spaced apart from each other in the first direction; and a mass addition film extended in the first direction to cover the top surface of the plurality of IDT electrodes and the top surface of the substrate exposed between the plurality of IDT electrodes. The thickness of the mass addition film on the top surface of the substrate and the thickness of the mass addition film on the top surface of the plurality of IDT electrodes are different from each other.

An acoustic wave resonator includes: a piezoelectric substrate; and an IDT located on the piezoelectric substrate and including a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including a grating electrode exciting an acoustic wave and a bus bar to which the grating electrode is connected, wherein an anisotropy coefficient in a cross region where the grating electrodes of the pair of comb-shaped electrodes cross each other is positive; an anisotropy coefficient in a gap region located between a tip of the grating electrode of one of the pair of comb-shaped electrodes and the bus bar of the other is less than the anisotropy coefficient in the cross region, and an acoustic velocity of an acoustic wave propagating through the gap region is equal to or less than an acoustic velocity of an acoustic wave propagating through the cross region at an antiresonant frequency.

A surface acoustic wave device includes: a pair of comb-type electrodes that are provided on a piezoelectric substrate and include electrode fingers and dummy electrode fingers, the electrode fingers of one of the pair of comb-type electrodes facing the dummy electrode fingers of the other comb-type electrode; and additional films that are provided to cover gaps between tip ends of the electrode fingers and tip ends of the dummy electrode fingers and to overlap with at least one of first through third groups in which the first and second groups respectively include the electrode fingers and the dummy electrode fingers located at opposite sides of the gaps in a first direction in which the electrode fingers extend, and the third group includes the electrode fingers located at sides of the gaps in a second direction that crosses the first direction.

An acoustic wave device includes a piezoelectric substrate and an interdigital transducer disposed on the piezoelectric substrate, the interdigital transducer including a center region, first and second edge regions, and first and second gap regions, a temperature compensation layer covering the interdigital transducer, and a floating metal layer buried in the temperature compensation layer or disposed on top of the temperature compensation layer. The floating metal layer includes a plurality of floating metal blocks spaced apart from each other and overlapping at least the first and second edge regions of the interdigital transducer.

A surface acoustic wave (SAW) resonator device is provided. The SAW resonator device includes a first electrode positioned on an upper surface of a piezoelectric film. The first electrode may include a plurality of layers wherein a layer of the plurality of layers is a first heavy metal layer. The SAW resonator device may also include a first piezoelectric trench (PZT) positioned adjacent to the first electrode. The first PZT includes a recess in the piezoelectric film.