An acoustic wave device includes a support substrate, a piezoelectric layer, and a functional electrode. As seen in a first direction of the support substrate, the piezoelectric layer overlaps the support substrate. The functional electrode extends over a first major surface of the piezoelectric layer. A space is opposite to the first major surface of the piezoelectric layer and at or adjacent to a second major surface of the piezoelectric layer. In the first direction, the functional electrode extends over an overlap region that overlaps the space, and a non-overlap region that does not overlap the space. In the non-overlap region, at least one of an insulating film and a void is located between the functional electrode and the piezoelectric layer.

An acoustic wave device includes a support substrate, a silicon nitride film stacked on the support substrate, a silicon oxide film stacked on the silicon nitride film, a piezoelectric body stacked on the silicon oxide film and made of lithium tantalite, and an IDT electrode provided on one main surface of the piezoelectric body. For a wavelength normalized film thickness of the piezoelectric body, an Euler angle of the piezoelectric body, a wavelength normalized film thickness of the silicon nitride film, a wavelength normalized film thickness of the silicon oxide film, and a wavelength normalized film thickness of the IDT electrode, values are set so that at least one of a response intensity of a first higher order mode, corresponding to the response intensity of a second higher order mode, and of a response intensity of a third higher mode is greater than about −2.4.

An elastic wave device includes an IDT electrode on a second main surface of an element substrate that includes a piezoelectric layer, a support layer on the second main surface and surrounding the IDT electrode, a cover member on the support layer, and routing wiring lines extending from the second main surface of the element substrate onto side surfaces of the element substrate.

An elastic wave device includes an IDT electrode on a second main surface of an element substrate that includes a piezoelectric layer, a support layer on the second main surface and surrounding the IDT electrode, a cover member on the support layer, and routing wiring lines extending from the second main surface of the element substrate onto side surfaces of the element substrate.

Embodiments disclosed herein include diagnostic substrates and methods of using the diagnostic substrates to extract plasma parameters. In an embodiment, a diagnostic substrate comprises a substrate and an array of resonators across the substrate. In an embodiment, the array of resonators comprises at least a first resonator with a first structure and a second resonator with a second structure. In an embodiment, the first structure is different than the second structure.

An acoustic wave device is disclosed. The acoustic wave device can include a support substrate that includes a first substrate portion, a second substrate portion, and a third substrate portion between the first substrate portion and the second substrate portion. The acoustic wave device can include a piezoelectric layer that includes a first portion over the first substrate portion and a second portion over the second substrate portion. The piezoelectric layer can be arranged such that a region over the third substrate portion is free from the piezoelectric layer. The acoustic wave device can include a filter circuit formed on the first portion of the piezoelectric layer. The acoustic wave device can include a cancelation circuit on the second portion of the piezoelectric layer.

A filter includes a support substrate, a piezoelectric layer, one or more series resonators connected in series between input and output terminals, each having first electrode fingers having a first average pitch, one or more parallel resonators having one end connected to a path and another end connected to a ground, each having second electrode fingers having a second average pitch more than a maximum first average pitch, another resonator having one end connected to the path, and having third electrode fingers having a third average pitch less than or equal to an intermediate value between the maximum first average pitch and a minimum second average pitch, and an inductor having one end connected to the another resonator and another end connected to the ground, and having an inductance more than a maximum inductance of another inductor connected between the parallel resonators and the ground.

A filter includes a support substrate, a piezoelectric layer, one or more series resonators connected in series between input and output terminals, each having first electrode fingers having a first average pitch, one or more parallel resonators having one end connected to a path and another end connected to a ground, each having second electrode fingers having a second average pitch more than a maximum first average pitch, another resonator having one end connected to the path, and having third electrode fingers having a third average pitch less than or equal to an intermediate value between the maximum first average pitch and a minimum second average pitch, and an inductor having one end connected to the another resonator and another end connected to the ground, and having an inductance more than a maximum inductance of another inductor connected between the parallel resonators and the ground.

A surface acoustic wave resonator includes one IDT electrode and reflectors. When a distance between an electrode finger Fe(k) and an electrode finger Fe(k+1) is defined as a k-th electrode finger pitch, in an electrode finger Fe(k−1), the electrode finger Fe(k), and the electrode finger Fe(k+1), a value obtained by dividing a difference between the electrode finger pitch and a section average electrode finger pitch, which is an average of the electrode finger pitch and the electrode finger pitch, by an overall average electrode finger pitch is defined as a pitch deviation ratio, and a distribution obtained by calculating the pitch deviation ratio for all electrode fingers of the IDT electrode or the reflectors is defined as a histogram of the pitch deviation ratio, the IDT electrode or the reflectors have a standard deviation of the pitch deviation ratio in the histogram larger than or equal to about 0.2%.

An elastic wave device includes a supporting substrate including an upper surface including a recessed portion, a piezoelectric thin film on the supporting substrate to cover the recessed portion of the supporting substrate, an IDT electrode on a main surface of the piezoelectric thin film, the main surface being adjacent to the supporting substrate, and an intermediate layer on a main surface of the piezoelectric thin film, the main surface being remote from the supporting substrate. A space is defined by the supporting substrate and the piezoelectric thin film. The IDT electrode faces the space. Through holes are provided in the piezoelectric thin film and the intermediate layer to extend from a main surface of the intermediate layer to the space, the main surface being remote from the piezoelectric thin film. The elastic wave device further includes a cover member on the intermediate layer and covering opening ends of the through holes.