Title:
ELASTIC WAVE DEVICE
Document Type and Number:
WIPO Patent Application WO/2023/136294
Kind Code:
A1
Abstract:
Provided is an elastic wave device in which the frequency at which an unwanted wave is generated can be moved away from an anti-resonance frequency. An elastic wave device 10 according to the present invention is provided with: a piezoelectric substrate comprising a support member including a support substrate, and a piezoelectric layer 14 provided on the support member and composed of lithium tantalate or lithium niobate; a function electrode (IDT electrode 11) provided on the piezoelectric layer 14 and comprising at least one pair of electrode fingers; and a dielectric film 25 provided on the piezoelectric layer 14 so as to cover the at least one pair of electrode fingers (first electrode finger 28 and second electrode finger). In a plan view, an acoustic reflection portion is formed in a position overlapping at least a part of the function electrode. If the thickness of the piezoelectric layer 14 is d and the center-to-center distance of adjacent electrode fingers is p, d/p is less than or equal to 0.5. The electrode fingers include a first surface 11a and a second surface 11b opposite each other in the thickness direction, and side surfaces (first and second side surface portions 11c, 11d) connected to the first surface 11a and the second surface 11b. Of the first surface 11a and the second surface 11b, the second surface 11b is positioned on the piezoelectric layer 14 side. The dielectric film 25 includes an electrode finger surface covering portion 25a covering the first surface 11a of the electrode fingers, side surface covering portions (first and second side surface covering portions 25c, 25d) covering the side surfaces of the electrode fingers, and a piezoelectric layer covering portion 25b covering the piezoelectric layer 14. The electrode finger surface covering portion 25a includes a central portion 25x positioned at the center in a direction orthogonal to a direction in which the electrode fingers extend. The side surface covering portions and the piezoelectric layer covering portion 25b are connected at connection portions (first and second connection portions 25e, 25f). If the minimum value of the thickness of the connection portions is tcm, tcm ≥ 0. If the thickness of the central portion 25x of the electrode finger surface covering portion 25a is te, te > tcm.
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Inventors:
DAIMON KATSUYA (JP)
IYAMA AKIHIRO (JP)
IYAMA AKIHIRO (JP)
Application Number:
PCT/JP2023/000612
Publication Date:
July 20, 2023
Filing Date:
January 12, 2023
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145
Domestic Patent References:
| WO2020095586A1 | 2020-05-14 | |||
| WO2021060513A1 | 2021-04-01 | |||
| WO2021177108A1 | 2021-09-10 |
Foreign References:
| JP2021527344A | 2021-10-11 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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