US 12,457,902 B2
Piezoelectric element
Yutaka Kishimoto, Nagaokakyo (JP); Shinsuke Ikeuchi, Nagaokakyo (JP); Masayuki Suzuki, Nagaokakyo (JP); and Fumiya Kurokawa, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Mar. 15, 2022, as Appl. No. 17/694,730.
Application 17/694,730 is a continuation of application No. PCT/JP2020/021062, filed on May 28, 2020.
Claims priority of application No. 2019-168109 (JP), filed on Sep. 17, 2019.
Prior Publication US 2022/0209098 A1, Jun. 30, 2022
Int. Cl. H01L 41/09 (2006.01); H01L 41/047 (2006.01); H01L 41/187 (2006.01); H01L 41/29 (2013.01); H01L 41/332 (2013.01); H10N 30/06 (2023.01); H10N 30/082 (2023.01); H10N 30/20 (2023.01); H10N 30/853 (2023.01); H10N 30/87 (2023.01)
CPC H10N 30/2047 (2023.02) [H10N 30/06 (2023.02); H10N 30/082 (2023.02); H10N 30/8542 (2023.02); H10N 30/87 (2023.02)] 16 Claims
OG exemplary drawing
 
1. A piezoelectric element comprising:
a piezoelectric layer including a first surface, a second surface opposed to the first surface, and a through-hole extending from the first surface to the second surface;
a first electrode layer adjacent to the first surface of the piezoelectric layer;
a second electrode layer adjacent to the second surface of the piezoelectric layer, at least a portion of the second electrode layer being opposed to the first electrode layer with the piezoelectric layer interposed therebetween, the second electrode layer facing the through-hole; and
a connecting electrode on a connecting surface of the second electrode layer, the connecting surface facing the through-hole;
wherein
the second electrode layer includes silicon as a major component;
the connecting electrode is made of a metal; and
a surface roughness Ra of the connecting surface is greater than a surface roughness Ra of a major surface, the major surface being a portion, other than the connecting surface, of a surface of the second electrode layer, the surface being adjacent to the piezoelectric layer.