Title:
ELASTIC WAVE DEVICE
Document Type and Number:
WIPO Patent Application WO/2023/136293
Kind Code:
A1
Abstract:
Provided is an elastic wave device that can suppress unnecessary waves near the resonant frequency. This elastic wave device 10 comprises: a piezoelectric substrate having a support member including a support substrate, and a piezoelectric layer 14 provided on the support member and made of lithium tantalate or lithium niobate; a functional electrode (IDT electrode 11) provided on the piezoelectric layer 14 and having at least one pair of electrode fingers; and a dielectric film 25 that is provided on the piezoelectric layer 14 so as to cover the at least one pair of electrode fingers. An acoustic reflection part is formed at a position overlapping at least a portion of the functional electrode in a plan view. When the thickness of the piezoelectric layer 14 is d, and the center-to-center distance between adjacent electrode fingers is p, d/p is 0.5 or less. The electrode fingers have a first surface 11a and a second surface 11b facing each other in the thickness direction, and side surfaces connecting to the first surface 11a and the second surface 11b. The first surface 11a among the first surface 11a and the second surface 11b is positioned on the piezoelectric layer 14 side. The side surfaces of the electrode fingers have a first side surface part 11c and a second side surface part 11d facing each other in a direction orthogonal to the direction in which the electrode fingers extend. The dielectric film 25 has a first side surface cover part 25c covering the first side surface part 11c of the electrode fingers, and a second side surface cover part 25d covering the second side surface part 11d. The first side surface cover part 25c includes a first outer surface 25e. The second side surface cover part 25d includes a second outer surface 25f. The angle formed between the first surface 11a and the first side surface part 11c of the electrode fingers is defined as θ1, and the angle formed between the first surface 11a and the second side surface part 11d is defined as θ2. The angle formed between the first outer surface 25e and a first virtual plane N1 extending in parallel to the first surface 11a from an edge portion of the first outer surface 25e of the dielectric film 25 on the piezoelectric layer 14 side toward the second side surface cover part 25d side, is defined as θ3, and the angle, formed between the second outer surface 25f and a second virtual plane extending parallel to the first surface 11a from an edge portion of the second outer surface 25f on the piezoelectric layer 14 side toward the first side surface cover part 25c side, is defined as θ4. The elastic wave device 10 satisfies at least one among θ1≠θ3 and θ2≠θ4.
Inventors:
DAIMON KATSUYA (JP)
IYAMA AKIHIRO (JP)
IYAMA AKIHIRO (JP)
Application Number:
PCT/JP2023/000611
Publication Date:
July 20, 2023
Filing Date:
January 12, 2023
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145
Domestic Patent References:
| WO2021060513A1 | 2021-04-01 | |||
| WO2002035702A1 | 2002-05-02 | |||
| WO2020080465A1 | 2020-04-23 |
Foreign References:
| JP2007074754A | 2007-03-22 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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