An acoustic wave resonator comprises a carrier substrate, a layer of dielectric material disposed on an upper surface of the carrier substrate, and a layer of piezoelectric material disposed above the layer of dielectric material. The layer of piezoelectric material includes a pair of opposing terminating edges that are coterminous with the layer of dielectric material. One or more interdigital transducers (IDTs) are disposed on the layer of piezoelectric material. The opposing terminating edges sandwich the one or more interdigital transducers, and in some examples, a pair of reflector gratings disposed on the layer of piezoelectric material and each including less than eight reflector fingers. The opposing terminating edges provide edge reflections that allow a reduction in size or a complete removal of the reflector gratings, resulting in a smaller acoustic wave resonator compared to conventional devices while maintaining a comparable performance.

An end-surface-reflection surface acoustic wave device, which reflects a surface acoustic wave between first and second end surfaces facing each other, includes a support substrate, an intermediate layer, a piezoelectric layer, and an IDT electrode. The first end surface is located at one end portion in a surface-acoustic-wave propagation direction and extends from a main surface of the piezoelectric layer to at least a portion of the intermediate layer. The second end surface is located at the other end portion in the surface-acoustic-wave propagation direction and extends from the main surface of the piezoelectric layer to at least a portion of the intermediate layer. The support substrate includes support substrate portions that are located outside the first and second end surfaces in the surface-acoustic-wave propagation direction.

A ceramic substrate is formed of a polycrystalline ceramic and has a supporting main surface. The supporting main surface has a roughness of 0.01 nm or more and 3.0 nm or less in terms of Sa. The number of projections and depressions with a height of 1 nm or more in a square region with 50 μm sides on the supporting main surface is less than 5 on average, and the number of projections and depressions with a height of 2 nm or more in the square region is less than 1 on average.

An acoustic wave device is provided that includes a support substrate, a piezoelectric layer on the support substrate, and an interdigital transducer electrode. A ratio d/p is less than or equal to approximately 0.5, where d is a thickness of the piezoelectric layer and p is a distance between centers of adjacent electrode fingers of the multiple electrode fingers. The interdigital transducer electrode includes an intersection region in which the adjacent electrode fingers overlap when viewed in a direction in which multiple electrode fingers face each other. Moreover, two gap regions are located between the intersection region and a corresponding one of the two busbars and includes an I-B gap that is a dimension in a direction in which the multiple electrode fingers extend. The I-B gap of at least one of the two gap regions is less than or equal to about 1.1p.

An acoustic wave device includes a support including a support substrate, a piezoelectric layer on the support, a functional electrode at the piezoelectric layer, a frame-shaped support frame on the piezoelectric layer and surrounding the functional electrode in a plan view in a stacking direction of the support and the piezoelectric layer, and a lid covering an opening of the support frame, wherein the support includes a first cavity at a position overlapping at least a portion of the functional electrode in the plan view, a second cavity defined by the piezoelectric layer, the support frame, and the lid between the piezoelectric layer and the lid, the piezoelectric layer includes a through hole communicating with the first and second cavities, and the first and second cavities are under vacuum.

A coupled cavity filter structure that uses a surface acoustic wave, in particular, a guided surface acoustic wave, comprises an acoustic wave propagating substrate, at least one input transducer structure and one output transducer structure, provided over the substrate, each comprising inter-digitated comb electrodes, at least one reflecting structure comprising at least one or more metallic strips, positioned at a distance and in between the input and output transducer structures, in the direction of propagation of an acoustic wave. The acoustic wave propagating substrate is a composite substrate comprising a base substrate and a piezoelectric layer. In additional embodiments, a coupled cavity filter structure comprises a groove. In additional embodiments, a SAW ladder filter device comprises at least two coupled cavity filter structures as described herein, wherein the at least two coupled cavity filter structures are positioned on a single line.

A guided acoustic wave device includes a substrate, a lithium tantalate layer on the substrate, and a transducer on the lithium tantalate film. The lithium tantalate has a crystalline orientation defined by (YXl)Θ°, where Θ is between 10° and 37°. The inventors discovered that limiting the crystalline orientation of the lithium tantalate in this manner provides significant increases in the electromechanical coupling coefficient of the acoustic wave device, thereby increasing bandwidth and improving performance.

A coupled cavity filter structure that uses a surface acoustic wave, in particular, a guided surface acoustic wave, comprises an acoustic wave propagating substrate, at least one input transducer structure and one output transducer structure, provided over the substrate, each comprising inter-digitated comb electrodes, at least one reflecting structure comprising at least one or more metallic strips positioned at a distance and in between the input and output transducer structures, in the direction of propagation of an acoustic wave. The acoustic wave propagating substrate is a composite substrate comprising a base substrate and a piezoelectric layer. In additional embodiments, a coupled cavity filter structure comprises a groove. In additional embodiments, a SAW ladder filter device comprises at least two coupled cavity filter structures as described herein, wherein the at least two coupled cavity filter structures are positioned on a single line.

A device including a piezoelectric substrate, an interdigital transducer (IDT), and an antireflective structure is disclosed herein. The piezoelectric substrate has a front-side surface and a smoothed back-side surface. The IDT is on the front-side surface of the piezoelectric substrate. The antireflective structure is over at least a portion of the smoothed back-side surface of the piezoelectric substrate. By having the antireflective structure on at least a portion of the smoothed back-side surface of the piezoelectric substrate, reflection of spurious bulk acoustic waves toward the front-side surface of the piezoelectric substrate can be reduced and/or eliminated to lessen interference with surface acoustic waves. The reduction and/or elimination of spurious bulk acoustic waves allows the device to forego conventional roughening of the back-side surface of the piezoelectric substrate, thereby reducing fractures at the back-side surface and allowing for singulation techniques capable of producing smaller die sizes.

A guided acoustic wave device includes a substrate, a lithium tantalate layer on the substrate, and a transducer on the lithium tantalate film. The lithium tantalate has a crystalline orientation defined by (YXl), where is between 10 and 37. The inventors discovered that limiting the crystalline orientation of the lithium tantalate in this manner provides significant increases in the electromechanical coupling coefficient of the acoustic wave device, thereby increasing bandwidth and improving performance.