A composite substrate includes a support substrate made of Si, a high acoustic velocity material layer, a low acoustic velocity film, and a piezoelectric layer. In Euler angles (φ, θ, ψ) of the Si, φ and θ are within regions indicated by hatching with slant lines in FIG. 4. An acoustic wave device includes an IDT electrode in contact with the piezoelectric layer of the composite substrate.

A composite substrate includes a support substrate made of Si, a high acoustic velocity material layer, a low acoustic velocity film, and a piezoelectric layer. In Euler angles (φ, θ, ψ) of the Si, φ and θ are within regions indicated by hatching with slant lines in FIG. 4. An acoustic wave device includes an IDT electrode in contact with the piezoelectric layer of the composite substrate.

A surface acoustic wave device includes a piezoelectric substrate and a multi-layer interdigital transducer electrode disposed on the piezoelectric substrate. The multi-layer interdigital transducer electrode includes a first electrode layer and a second electrode layer. The second electrode layer is disposed between the piezoelectric substrate and the first electrode layer. The first electrode layer has a higher density than a density of the second electrode layer. The second electrode layer has a higher conductivity than a conductivity of the first electrode layer. Related radio frequency modules and wireless communication devices are also provided.

A packaged acoustic wave component is disclosed. The packaged acoustic wave component can include a first acoustic wave resonator that includes a first interdigital transducer electrode that is positioned over a first piezoelectric layer. The packaged acoustic wave component can also include a second acoustic wave resonator including a second interdigital transducer electrode positioned over a second piezoelectric layer. The second piezoelectric layer is bonded to the first piezoelectric layer. The packaged acoustic wave component can further include a stopper structure that is positioned over the first piezoelectric layer. The first stopper structure is positioned above a via and extends through the first piezoelectric layer. The stopper structure is in electrical communication with the first interdigital transducer electrode and includes a material which reflects at least fifty percent of light having a wavelength of 355 nanometers.

A packaged acoustic wave component is disclosed. The packaged acoustic wave component can include a first acoustic wave resonator that includes a first interdigital transducer electrode that is positioned over a first piezoelectric layer. The packaged acoustic wave component can also include a second acoustic wave resonator including a second interdigital transducer electrode positioned over a second piezoelectric layer. The second piezoelectric layer is bonded to the first piezoelectric layer. The packaged acoustic wave component can further include a stopper structure that is positioned over the first piezoelectric layer. The first stopper structure is positioned above a via and extends through the first piezoelectric layer. The stopper structure is in electrical communication with the first interdigital transducer electrode and includes a material which reflects at least fifty percent of light having a wavelength of 355 nanometers.

An acoustic wave device includes an IDT electrode and reflector electrodes on or above a piezoelectric substrate. A region in which first and second electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction defines an intersection region. The intersection region includes a center region and first and second edge regions on both sides of the center region. Dielectric films extend from the first and second edge regions to outer side regions in the acoustic wave propagation direction of the reflector electrodes via the reflector electrodes.

An acoustic wave device includes an IDT electrode and reflector electrodes on or above a piezoelectric substrate. A region in which first and second electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction defines an intersection region. The intersection region includes a center region and first and second edge regions on both sides of the center region. Dielectric films extend from the first and second edge regions to outer side regions in the acoustic wave propagation direction of the reflector electrodes via the reflector electrodes.

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.

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.

An acoustic wave device includes a piezoelectric substrate and an IDT electrode. The IDT electrode includes a center area and first and second edge areas. Areas including the first and second edge areas and overlapping the areas in an acoustic-wave propagation direction include first and second expansion edge areas. First and second acoustic-velocity adjusters are provided in the first and second expansion edge areas. The first and second acoustic-velocity adjusters respectively includes first and second end portions and third and fourth end portions. The first to fourth end portions are located at outer sides of the first and second edge areas. End portions in at least one of two pairs including a pair of first and third end portions and a pair of second and fourth end portions do not overlap each other in a direction in which electrode fingers extend.