Acoustic wave device
AssigneeMurata Manufacturing Co., Ltd.
InventorsKatsuya Daimon, Akihiro Iyama
Life of this patent
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Abstract
An acoustic wave device includes a piezoelectric substrate including a support that includes a support substrate, and a piezoelectric layer located on the support, a functional electrode located on the piezoelectric layer and including at least one pair of electrode fingers, and a dielectric film located on the piezoelectric layer to cover the at least one pair of electrode fingers. An acoustic reflection portion is located at a position overlapping at least a portion of the functional electrode in plan view. Assuming a thickness of the piezoelectric layer is d and a center-to-center distance between the electrode fingers adjacent to each other is p, d/p is about 0.5 or less. Angles of corners θ1, θ2, θ3, and θ4 are such that at least one of θ1≠θ3 or θ2≠θ4 is satisfied.
Claims20
An acoustic wave device comprising:
- a piezoelectric substrate including a support that includes a support substrate, and a piezoelectric layer that is provided on the support and includes lithium tantalate or lithium niobate;
- a functional electrode provided on the piezoelectric layer and including at least one pair of electrode fingers;
- and
- a dielectric film provided on the piezoelectric layer to cover the at least one pair of electrode fingers;
- wherein
- an acoustic reflection portion is provided at a position overlapping at least a portion of the functional electrode in plan view;
- in a case where a thickness of the piezoelectric layer is d and a center-to-center distance between the at least one pair of electrode fingers adjacent to each other is p, d/p is about 0.5 or less;
- each of the at least one pair of electrode fingers includes a first surface and a second surface that face each other in a thickness direction, and a side surface that is connected to the first surface and the second surface, the first surface being located on a piezoelectric layer side;
- the side surface of each of the at least one pair of electrode fingers includes a first side surface portion and a second side surface portion that face each other in a direction perpendicular or substantially perpendicular a direction in which each of the at least one pair of electrode fingers extends;
- the dielectric film includes a first side surface cover portion that covers the first side surface portion of each of the at least one pair electrode fingers, and a second side surface cover portion that covers the second side surface portion of each of the at least one pair of electrode fingers, the first side surface cover portion including a first outer surface, the second side surface cover portion including a second outer surface;
- and
- in a case where an angle of a corner defined by the first surface and the first side surface portion of each of the at least one pair of electrode fingers is θ1, an angle of a corner defined by the first surface and the second side surface portion is θ2, an angle of a corner defined by a first virtual plane extending parallel or substantially parallel to the first surface from an edge portion of the first outer surface of the dielectric film on the piezoelectric layer side toward a second side surface cover portion side, and the first outer surface is θ3, and an angle of a corner defined by a second virtual plane extending parallel or substantially parallel to the first surface from an edge portion of the second outer surface on the piezoelectric layer side toward a first side surface cover portion side, and the second outer surface is θ4, at least one of θ1≠θ3 or θ2≠θ4 is satisfied.
Dependencies are inferred from the claim text.