Title:
ELASTIC WAVE DEVICE
Document Type and Number:
WIPO Patent Application WO/2023/136291
Kind Code:
A1
Abstract:
Provided is an elastic wave device in which the frequency at which an unwanted wave is generated can be distanced from an anti-resonance frequency. An elastic wave device 10 according to the present invention comprises: 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. In a plan view taken along a stacking direction of the support member and the piezoelectric layer 14, an acoustic reflection portion is formed in a position overlapping with 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; side surfaces (first and second side surface portions 11c, 11d) connected to the first surface 11a and the second surface 11b; and electrode finger ridge portions (first and second electrode finger ridge portions 11e, 11f) to which the side surfaces and the first surface 11a are connected. 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 cover portion 25a covering the first surface 11a of the electrode fingers; side surface cover portions (first and second side surface cover portions 25c, 25d) covering the side surfaces of the electrode fingers; and dielectric film ridge portions (first and second dielectric film ridge portions 25e, 25f) to which the side surface cover portions and the electrode finger surface cover portion 25a are connected. The dielectric film ridge portions and the electrode finger ridge portions are both curved, wherein the radius of curvature of at least a part of the dielectric film ridge portions is greater than the radius of curvature of at least a part of the electrode finger ridge portions.
Inventors:
DAIMON KATSUYA (JP)
IYAMA AKIHIRO (JP)
IYAMA AKIHIRO (JP)
Application Number:
PCT/JP2023/000608
Publication Date:
July 20, 2023
Filing Date:
January 12, 2023
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145; H03H9/25; H03H9/64
Domestic Patent References:
| WO2021060521A1 | 2021-04-01 | |||
| WO2020158673A1 | 2020-08-06 |
Foreign References:
| US20200021271A1 | 2020-01-16 | |||
| JP2005176152A | 2005-06-30 | |||
| JP2005348139A | 2005-12-15 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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