An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate and including electrode fingers. A portion where adjacent electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction is an intersecting region. The intersecting region includes a central region located in a central portion in a direction in which the electrode fingers extend and first and second edge regions on both sides of the central region in the direction in which the electrode fingers extend. The acoustic wave device further includes dielectric films between the piezoelectric substrate and the electrode fingers in the first and second edge regions. The dielectric films include at least one of hafnium oxide, niobium oxide, tungsten oxide, or cerium oxide.

Aspects of this disclosure relate to an acoustic wave resonator with transverse 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.

The present invention relates to a transducer structure with transverse mode suppression means, in particular for a single-port resonator, comprising a piezoelectric substrate (120, 170), at least a pair of inter-digitated comb electrodes (102, 112) formed on the piezoelectric substrate (120, 170), wherein the first comb electrode (102) comprises a first bus bar (108) and a plurality of electrode fingers (104) alternating with shorter dummy electrode fingers (106), both extending from the first bus bar (108), wherein the second comb electrode (112) comprises a second bus bar (118) and a plurality of electrode fingers (114) extending from the second bus bar (118), wherein the dummy electrode fingers (106) of the first bus bar (108) face the electrode fingers (114) of the second bus bar (118) and are separated from the electrode fingers (114) by first gaps (110a), characterized in further comprising a transverse mode suppression layer (122, 132, 222, 232, 422, 432) provided partially underneath the first gap (110a) and chosen such that the phase velocity of a guided wave is smaller in the region of the transverse mode suppression layer (122, 132, 222, 232, 422, 432) compared to the phase velocity of the guided wave in the central region (136) underneath the alternating electrodes fingers (104, 114) of the first and second electrodes (102, 112). The present invention also relates to a method for fabricating the transducer structure as previously described and to a single-port resonator comprising at least one structure as previously described.

An acoustic wave filter device includes at least one series arm resonator and a parallel arm resonator. The series arm resonators and the parallel arm resonator are defined by acoustic wave resonators, an interdigital transducer electrode of the series arm resonators is an apodized interdigital transducer electrode subjected to apodization weighting, in the interdigital transducer electrode of the parallel arm resonator, an intersecting portion includes a central region and low acoustic velocity regions provided at both outer side portions of the central portion, an acoustic velocity of an acoustic wave in the low acoustic velocity region is lower than an acoustic velocity of an acoustic wave in the central region, and a high acoustic velocity region where an acoustic velocity of an acoustic wave is higher than that of the low acoustic velocity region is provided at an outer side portion of each of the low acoustic velocity regions.

Aspects of this disclosure relate to a surface acoustic wave device. The surface acoustic wave device includes a piezoelectric layer and an interdigital transducer. The interdigital transducer electrode includes a pair of electrodes, each electrode having a bus bar and fingers extending from the bus bar. The interdigital transducer electrode has an interdigital region defined by a portion of the fingers of the electrodes that interdigitate with each other. A dielectric layer is disposed over the interdigital transducer electrode outside the interdigital region and configured to reduce a loss of the surface acoustic wave device.

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer that is positioned partially between the piezoelectric layer and the interdigital transducer electrode. The dielectric layer that is positioned so as to partially electro-mechanically de-couple the piezoelectric layer from the interdigital transducer electrode.

An acoustic wave device includes an interdigital transducer electrode connected to first and second terminals, and a reflector connected to the second terminal. In a group of electrode fingers of the interdigital transducer electrode, the electrode fingers at one end and another end in a second direction are respectively first and second end electrode fingers, the first end electrode finger includes a wide portion at a distal end portion. The first end electrode finger is located between the reflector and the second end electrode finger in the second direction. An inner busbar portion of one of first and second busbars not connected to the first end electrode finger, is located on an inner side in the second direction relative to the wide portion of the first end electrode finger so as not to overlap the wide portion of the first end electrode finger in a first direction.

An interdigital transducer electrode that is provided on a piezoelectric film includes a first busbar, a second busbar, multiple first electrode fingers, and multiple second electrode fingers. The first electrode fingers and the second electrode fingers overlap in a region in a direction in which an acoustic wave propagates, and the region includes a central region, a first edge region that is located between the central region and the first busbar, and a second edge region that is located between the central region and the second busbar. An acoustic velocity in the first edge region and the second edge region is lower than an acoustic velocity in the central region. An acoustic velocity in a busbar region is higher than the acoustic velocity in the central region.

An elastic wave device includes a high-acoustic-velocity member, a low-acoustic-velocity film, a piezoelectric film, and am interdigital transducer electrode stacked in this order. The interdigital transducer electrode includes an intersecting region and outer edge regions. The intersecting region includes a central region located in the middle of the intersecting region in the direction in which electrode fingers extend and the inner edge regions located at the respective outer side portions of the central region. The electrode fingers in the inner edge regions have a larger thickness than in the central region. Each electrode finger has an incrased thickness portion. The increased thickness portion is made of a metal having a density d of about 5.5 g/cm.sup.3 or more and has a film thickenss equal to or smaller than a wavelength-normalized film thickness represented by T (%)=−0.1458d+4.8654.

In an acoustic wave device, an interdigital transducer electrode is disposed on a piezoelectric substrate with a reverse velocity surface having an elliptic shape, and a dielectric film is disposed to cover the interdigital transducer electrode. Assuming an electrode density (%) of the interdigital transducer electrode to be y (%) and a wavelength-normalized film thickness 100h/λ (%) of the interdigital transducer electrode to be x (%), the wavelength-normalized film thickness x of the interdigital transducer electrode takes a value not less than x satisfying y=0.3452x.sup.2−6.0964x+36.262 depending on the electrode density of the interdigital transducer electrode.