A surface acoustic wave device comprises a substrate and an interdigital transducer (IDT) electrode disposed on the substrate. The IDT electrode includes a lower electrode layer having a lower surface in contact with an upper surface of the substrate and an upper electrode layer having a lower surface defining a base in contact with an upper surface of the lower electrode layer. Side surfaces of the lower electrode layer are substantially perpendicular to the upper surface of the substrate. Side surfaces of the upper electrode layer are disposed at an acute angle relative to the upper surface of the substrate.

A vibrator device includes a circuit element, which has a first terminal and is a quadrangle in plan view, a vibrator, which is disposed on an active surface and is a quadrangle in plan view, a base, on which the circuit element is disposed and which has a second terminal, and a wire which connects the first terminal and the second terminal together. In plan view of the circuit element, at least one side of the vibrator is disposed along a direction where the one side intersects each of two adjacent sides of the circuit element, and the vibrator does not overlap the first terminal.

An elastic wave filter device includes first and second reception filters, an input terminal, output terminals, and reference terminals provided on a piezoelectric substrate. The first reception filter includes series resonators and parallel resonators, and the second reception filter includes series resonators and parallel resonators. The reference terminal connected to the parallel resonator connected so as to be closest to the output terminal among the parallel resonators included in the first reception filter, and the reference terminal connected to the parallel resonator connected so as to be closest to the output terminal among the parallel resonators included in the second reception filter, are separated from each other on the piezoelectric substrate.

An elastic wave device includes a piezoelectric substrate, functional electrodes on the piezoelectric substrate, a support layer on the piezoelectric substrate with a frame shape surrounding the functional electrodes, a cover member on the support layer to seal an opening of the support layer, the cover member including a first main surface facing the support layer, and a second main surface opposite to the first main surface. Recesses are located in the cover member and are open to the second main surface. Via holes extend through the support layer and to bottom surfaces of the recesses of the cover member, the via holes each including an opening that is open to the bottom surface. The area of the opening of each of the via holes is not more than the area of the bottom surface of the corresponding recess of the cover member. First via conductor portions are provided in the via holes and second via conductor portions are provided in the recesses of the cover member.

An electronic device includes a support layer is provided on a piezoelectric substrate and surrounds a functional element. A cover layer is located above the support layer, and faces the piezoelectric substrate. A protective layer seals the support layer and the cover layer. The support layer is provided on at least the outer periphery of the piezoelectric substrate, and defines a hollow portion within the outer periphery of the piezoelectric substrate. The protective layer includes a first portion above the hollow portion, a second portion above the support layer, and a curved surface that is convex in an opposite direction from the piezoelectric substrate.

An acoustic wave device that utilizes a plate wave includes a recess in an upper surface of a support substrate. A piezoelectric substrate is located on the support substrate with a first principal surface side facing the support substrate. An IDT electrode is provided on the first principal surface of the piezoelectric substrate. The recess defines a cavity that is surrounded by the support substrate and the first principal surface of the piezoelectric substrate. The IDT electrode faces the cavity. The piezoelectric substrate includes through-holes that communicate the cavity and the second principal surface with each other. Sealing materials are filled respectively in the through-holes.

Certain aspects of the present disclosure provide a surface acoustic wave (SAW) resonator with piston mode design and electrostatic discharge (ESD) protections. An example electroacoustic device generally includes a piezoelectric material and a first electrode structure disposed above the piezoelectric material. The first electrode structure comprises first electrode fingers arranged within an active region having a first region and a second region. At least one of the first electrode fingers has at least one of a different width or a different height in the first region than in the second region, and the first electrode fingers comprise a first electrode finger that has a width or height in the second region that is less than a corresponding width or height of the at least one of the first electrode fingers in the second region.

A surface acoustic wave device comprises a substrate and an interdigital transducer (IDT) electrode disposed on the substrate. The IDT electrode includes a lower electrode layer having a lower surface in contact with an upper surface of the substrate and an upper electrode layer having a lower surface defining a base in contact with an upper surface of the lower electrode layer. Side surfaces of the lower electrode layer are substantially perpendicular to the upper surface of the substrate. Side surfaces of the upper electrode layer are disposed at an acute angle relative to the upper surface of the substrate.

A composite device includes a silicon substrate including first and second main surfaces on opposite sides, a semiconductor device adjacent to at least one of the first and second main surfaces, and an acoustic wave device including a silicon oxide film directly or indirectly disposed on the first main surface of the silicon substrate, a piezoelectric layer directly disposed on the silicon oxide film, and an IDT disposed on the piezoelectric layer. The piezoelectric layer has a thickness of not greater than about 2.5 where is a wavelength defined by an electrode finger pitch of the IDT.

An acoustic wave device comprises an IDT electrode disposed above an upper surface of a piezoelectric substrate and includes a plurality of electrode fingers configured to excite a main acoustic wave. A first dielectric film made of an oxide is disposed above the upper surface of the piezoelectric substrate and covers the plurality of electrode fingers. A second dielectric film made of non-oxide is disposed between the first dielectric film and each of the plurality of electrode fingers. A third dielectric film is disposed between the piezoelectric substrate and the plurality of electrode fingers. A speed of a transverse wave propagating through the third dielectric film is greater than a speed of the main acoustic wave propagating through the piezoelectric substrate. The third dielectric film contacts the first dielectric film between adjacent electrode fingers of the plurality of electrode fingers.