Title:
ELASTIC WAVE DEVICE
Document Type and Number:
WIPO Patent Application WO/2023/002790
Kind Code:
A1
Abstract:
Provided is an elastic wave device capable of suppressing unwanted waves at a frequency lower than and around a resonance frequency. 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; and an IDT electrode 11 provided on the piezoelectric layer 14 and having a pair of bus bars (first and second bus bars 26, 27) and a plurality of electrode fingers (first and second electrode fingers 28, 29). 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. Some of the plurality of electrode fingers are connected to one of the bus bars of the IDT electrode 11. The remaining electrode fingers of the plurality of electrode fingers are connected to the other bus bar. A plurality of electrode fingers connected to one bus bar and a plurality of electrode fingers connected to the other bus bar are interdigitated. If a direction in which adjacent electrode fingers oppose each other is defined as an electrode finger opposing direction, the adjacent electrode fingers overlap each other in an intersecting region F when viewed from the electrode finger opposing direction. If 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 H and a pair of edge regions (first and second edge regions E1, E2) disposed so as to sandwich the central region H in the electrode finger extending direction. At least one mass-adding film 24 is provided in at least the edge regions. If the dimension of the mass-adding film 24 along the electrode finger extending direction is defined as the length of the mass-adding film 24, and arbitrary two points in the electrode finger opposing direction in a portion in which the mass-adding film 24 is located are defined as a first point O1 and a second point O2, the length of the mass-adding film 24 is different between the first point O1 and the second point O2 of at least one group thereof.
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Inventors:
DAIMON KATSUYA (JP)
Application Number:
PCT/JP2022/024551
Publication Date:
January 26, 2023
Filing Date:
June 20, 2022
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145
Domestic Patent References:
| WO2020100949A1 | 2020-05-22 | |||
| WO2015182521A1 | 2015-12-03 | |||
| WO2020171050A1 | 2020-08-27 | |||
| WO2021060513A1 | 2021-04-01 |
Foreign References:
| JP2012186808A | 2012-09-27 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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