The present disclosure relates to acoustic wave devices, and particularly to high quality factor (Q) transducers for surface acoustic wave (SAW) devices. An exemplary SAW device includes an interdigital transducer (IDT) between two reflective gratings to form a resonator. The resonator operates through shear horizontal mode acoustic waves, and therefore suppression of transverse modes (parallel to electrode fingers of the IDT) is desired. A piston mode can be formed in the resonator to suppress transverse modes, which may also increase energy leakage and result in a lower Q. A higher Q is achieved by adding a fast region at an end of one or more of the electrode fingers of the IDT.

An acoustic wave device includes a piezoelectric substrate, a first band pass filter that is on the piezoelectric substrate and has a first pass band, and a second band pass filter that is on the piezoelectric substrate and has a second pass band at a higher frequency than the first pass band. The first and second band pass filters include resonators that include respective IDT electrodes. When a first total average metallization ratio is defined as an average of metallization ratios of all of the IDT electrodes included in the first filter and a second total average metallization ratio is defined as an average of metallization ratios of all of the IDT electrodes included in the second filter, the first total average metallization ratio is greater than the second total average metallization ratio.

Surface acoustic wave (SAW) devices and methods of fabricating SAW devices are disclosed. The disclosed SAW device includes a piezoelectric layer. The SAW device also includes at least one transducer coupled to the piezoelectric layer. The transducer includes a first set of electrodes and a second set of electrodes. Each electrode in the first set of electrodes is directly adjacent to at least one electrodes in the second set of electrodes along a wave propagation axis, and the first and second set of electrodes are separated from each other along a depth axis.

A surface acoustic wave (SAW) device comprises an interdigitated transducer structure and at least one acoustic wave reflective structure provided on or in an acoustic wave propagating substrate. The interdigitated transducer structure comprises a first material and the at least one acoustic wave reflective structure comprises a second material different from the first material and/or the acoustic wave reflective structure and the interdigitated transducer structure have different geometrical parameters. A sensor comprises a SAW device as described herein, and a method is used for manufacturing a SAW device comprising at least one acoustic wave reflective structure.

An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. An absolute value of a thermal expansion coefficient of the piezoelectric substrate is larger than an absolute value of a thermal expansion coefficient of the supporting substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the first acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the third acoustic impedance layer and the fourth acoustic impedance layer.

A surface acoustic wave (SAW) device includes a substrate; an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes formed on the substrate, wherein the interdigital electrodes includes central portions, end portions, and intermediate portions between the end portions and the lead-out portions, and a thickness of the interdigital electrodes at the end portions is greater than a thickness of the interdigital electrodes at the central portions and the intermediate portions, thereby forming protruding structures at the end portions of the interdigital electrodes; a protective layer formed on the protruding structures at the end portions of the interdigital electrodes; a first temperature compensation layer formed on the protective layer; a second temperature compensation layer formed on the first temperature compensation layer and on the central portions and the intermediate portions of the interdigital electrodes; and a passivation layer formed on the second temperature compensation layer.

An elastic wave device using the S0 mode of plate waves includes a support substrate, an acoustic reflective layer laminated on the support substrate, a piezoelectric body laminated on the acoustic reflective layer, and an IDT electrode disposed on the piezoelectric body. In the acoustic reflective layer, T1+T2 is between about 0.40 and about 0.60 inclusive in a portion in which low and high acoustic impedance layers are adjacent in the laminating direction. T1 is the thickness of the low acoustic impedance layers. T2 is the thickness of the high acoustic impedance layers. T1/(T1+T2) is between about 0.35 and about 0.65 inclusive.

The present disclosure relates to acoustic wave devices, and particularly to high quality factor (Q) transducers for surface acoustic wave (SAW) devices. An exemplary SAW device includes an interdigital transducer (IDT) between two reflective gratings to form a resonator. The resonator operates through shear horizontal mode acoustic waves, and therefore suppression of transverse modes (parallel to electrode fingers of the IDT) is desired. A piston mode can be formed in the resonator to suppress transverse modes, which may also increase energy leakage and result in a lower Q. A higher Q is achieved by adding a fast region at an end of one or more of the electrode fingers of the IDT.

A method for fabricating a surface acoustic wave (SAW) device includes forming an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes on a substrate, wherein the interdigital electrodes include central portions, end portions, and intermediate portions between the end portions and the lead-out portions; forming a protective layer on the IDT; forming a first temperature compensation layer on the protective layer; forming openings in the first temperature compensation layer to expose portions of the protective layer on the central portions and the intermediate portions of the interdigital electrodes; and etching the exposed portions of the protective layer, and etching the central portions and the intermediate portions of the interdigital electrodes to a preset thickness, to form protruding structures at the end portions of the interdigital electrodes.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode on the piezoelectric substrate. The IDT electrode includes a first comb-shaped electrode including first electrode fingers and a second comb-shaped electrode including second electrode fingers. The IDT electrode includes a first portion in which a main electrode layer includes a first metal and a second portion in which a main electrode layer includes a second metal. The first electrode fingers and the second comb-shaped electrode include first facing portions facing each other with a gap in between, and the second electrode fingers and the first comb-shaped electrode include second facing portions facing each other with a gap in between. At least one of the first facing portions and second facing portions is the second portion, and a portion of the IDT electrode other than the second portion is the first portion.