US 12,395,149 B2
Acoustic wave device
Masashi Omura, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Jun. 3, 2022, as Appl. No. 17/831,508.
Application 17/831,508 is a continuation of application No. PCT/JP2020/045191, filed on Dec. 4, 2020.
Claims priority of application No. 2019-221052 (JP), filed on Dec. 6, 2019.
Prior Publication US 2022/0294417 A1, Sep. 15, 2022
Int. Cl. H03H 9/17 (2006.01); H03H 9/02 (2006.01); H03H 9/13 (2006.01); H03H 9/56 (2006.01)
CPC H03H 9/173 (2013.01) [H03H 9/02015 (2013.01); H03H 9/02157 (2013.01); H03H 9/132 (2013.01); H03H 9/568 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An acoustic wave device comprising:
a piezoelectric member including a first main surface and a second main surface opposing each other and having anisotropic properties in a plane parallel or substantially parallel with the first and second main surfaces;
a first electrode on the first main surface of the piezoelectric member;
a second electrode on the second main surface of the piezoelectric member and opposing the first electrode with the piezoelectric member interposed therebetween;
an acoustic reflection section on a surface of the second electrode different from a surface of the second electrode on the piezoelectric member; and
an additional mass film for at least one of the first electrode and the second electrode, the additional mass film being in at least one of an area on the first electrode or the second electrode and an area outward of the first electrode or the second electrode; wherein
as viewed from above, a region where at least one of the first electrode and the additional mass film overlaps the second electrode includes a first region and a second region, the second region surrounding the first region;
in the second region, a configuration of additional mass film portions of the additional mass film located on corresponding sides of a first direction in a plane of the piezoelectric member and a configuration of additional mass film portions of the additional mass film located on corresponding sides of a second direction, the second direction being different from the first direction, in the plane of the piezoelectric member are different from each other;
the additional mass film is in the second region and defines a frame-shaped projecting section; and
at least one of a thickness and a material of the frame-shaped projecting section is different between each of the additional mass film portions on the corresponding sides of the first direction and each of the additional mass film portions on the corresponding sides of the second direction.