Title:
ELASTIC WAVE DEVICE
Document Type and Number:
WIPO Patent Application WO/2023/002824
Kind Code:
A1
Abstract:
Provided is an elastic wave device in which transverse modes can be effectively suppressed. An elastic wave device 10 of the present invention comprises: a support member including a support substrate; a piezoelectric layer 14 provided on the support member and comprising a lithium niobate layer or a lithium tantalate layer; a dielectric film 17 provided on the piezoelectric layer 14; and an IDT electrode 11 provided on the piezoelectric layer 14, at least partly provided on the dielectric film 17, and having a plurality of electrode fingers. The support member is provided with an acoustic reflecting portion. The acoustic reflecting portion overlaps at least a part of the IDT electrode 11 in plan view. If the thickness of the piezoelectric layer 14 is d and the distance between the centers of adjacent electrode fingers is p, d/p is 0.5 or less. When viewed from a direction in which adjacent electrode fingers oppose each other, the adjacent electrode fingers overlap each other in an intersecting region F. When the direction of extension of the plurality of electrode fingers is defined as an electrode finger extending direction, the intersecting region F includes a central region M and a pair of low acoustic velocity regions (first and second low acoustic velocity regions L1, L2) disposed so as to sandwich the central region M in the electrode finger extending direction. The low acoustic velocity regions are configured such that the acoustic velocity in the low acoustic velocity regions is lower than the acoustic velocity in the central region M. The dielectric film 17 overlaps at least the intersecting region F in plan view. If the thickness of the dielectric film 17 is d1 and the ratio of the thickness d1 of the dielectric film 17 and the thickness d of the piezoelectric layer 14 is a thickness ratio d1/d, the combination of the material of the dielectric film 17 and a thickness range of the dielectric film 17 is one of the combinations shown in Table 1.
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Inventors:
OKADA TAKURO (JP)
Application Number:
PCT/JP2022/025944
Publication Date:
January 26, 2023
Filing Date:
June 29, 2022
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145; H03H9/25
Domestic Patent References:
| WO2019065666A1 | 2019-04-04 | |||
| WO2019138810A1 | 2019-07-18 | |||
| WO2021065684A1 | 2021-04-08 | |||
| WO2021060513A1 | 2021-04-01 |
Foreign References:
| US20170155373A1 | 2017-06-01 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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