US 12,445,108 B2
Acoustic wave device
Katsuya Daimon, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Aug. 4, 2022, as Appl. No. 17/880,848.
Application 17/880,848 is a continuation of application No. PCT/JP2021/005611, filed on Feb. 16, 2021.
Claims priority of application No. 2020-024257 (JP), filed on Feb. 17, 2020.
Prior Publication US 2022/0385271 A1, Dec. 1, 2022
Int. Cl. H03H 9/25 (2006.01); H03H 9/02 (2006.01); H03H 9/145 (2006.01)
CPC H03H 9/25 (2013.01) [H03H 9/02559 (2013.01); H03H 9/02574 (2013.01); H03H 9/14541 (2013.01); H03H 9/02992 (2013.01)] 28 Claims
OG exemplary drawing
 
1. An acoustic wave device comprising:
a support substrate;
a piezoelectric film directly or indirectly on the support substrate; and
an IDT electrode on the piezoelectric film; wherein
when a wavelength defined by an electrode finger pitch of the IDT electrode is λ, a thickness of the piezoelectric film is about 1λ or less;
the piezoelectric film is a lithium tantalate film or a lithium niobate film;
the piezoelectric film has crystal axes [XP, YP, ZP];
the support substrate includes a first silicon layer and a second silicon layer laminated on the first silicon layer, and the second silicon layer is located closer to the piezoelectric film than the first silicon layer is in the support substrate;
a plane orientation of each of the first silicon layer and the second silicon layer is one of (100), (110), and (111);
in a silicon layer having a plane orientation of (111), when a direction vector obtained by projecting the ZP axis onto a (111) plane of the silicon layer is k111, an angle between the direction vector k111 and a [11-2] direction of silicon of the silicon layer is an angle α111;
in a silicon layer having a plane orientation of (110), when a direction vector obtained by projecting the ZP axis onto a (110) plane of the silicon layer is k110, an angle between the direction vector k110 and a [001] direction of silicon of the silicon layer is an angle α110;
in a silicon layer having a plane orientation of (100), when a direction vector obtained by projecting the ZP axis onto a (100) plane of the silicon layer is k100, an angle between the direction vector k110 and the [001] direction of silicon of the silicon layer is an angle α100;
when an angle between the plane orientation of the first silicon layer and the crystal axes of the piezoelectric film is an angle α1, and an angle between the plane orientation of the second silicon layer and the crystal axes of the piezoelectric film is an angle α2, each of the angle α1 and the angle α2 is one of three types of angles of the angle α100, the angle α110, and the angle α111; and
a type of the angle α1 is different from a type of the angle α2 and/or a value of the angle α1 is different from a value of the angle α2.