US 12,224,733 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 Oct. 4, 2021, as Appl. No. 17/492,752.
Application 17/492,752 is a continuation of application No. PCT/JP2020/015282, filed on Apr. 3, 2020.
Claims priority of application No. 2019-073691 (JP), filed on Apr. 8, 2019.
Prior Publication US 2022/0029600 A1, Jan. 27, 2022
Int. Cl. H03H 9/02 (2006.01); H03H 9/145 (2006.01); H03H 9/25 (2006.01)
CPC H03H 9/02574 (2013.01) [H03H 9/02559 (2013.01); H03H 9/02637 (2013.01); H03H 9/02866 (2013.01); H03H 9/02984 (2013.01); H03H 9/145 (2013.01); H03H 9/25 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An acoustic wave device comprising:
a silicon support substrate;
a silicon nitride film on the support substrate;
a silicon oxide film on the silicon nitride film;
a piezoelectric layer on the silicon oxide film and made of Y-cut X-SAW propagation lithium tantalate; and
an IDT electrode directly or indirectly on the piezoelectric layer and including a plurality of electrode fingers; wherein
when a wavelength defined by an electrode finger pitch of the IDT electrode is λ, a film thickness of the piezoelectric layer is equal to or less than about 1λ;
Euler angles of the piezoelectric layer are (about 0±5°, θ, about 0±5°) or (about 0±5°, θ, about 180±5°), and θ in the Euler angles of the piezoelectric layer is about 95.5°≤θ<117.5° or about −84.5°≤θ<−62.5°; and
a relationship between θ in the Euler angles of the piezoelectric layer and a film thickness of the silicon nitride film is a combination shown in Table 1 or Table 2 below:
 
 TABLE 1
 
 
 
 
 FILM THICKNESS OF SiN FILM
 
 θ LOWER LIMIT [λ] UPPER LIMIT [λ]
 
 
 
  95.5 ≤ θ < 96.5 0.0005 0.746
 
  96.5 ≤ θ < 97.5 0.0005 0.732
 
  97.5 ≤ θ < 98.5 0.0005 0.736
 
  98.5 ≤ θ < 99.5 0.0005 0.726
 
  99.5 ≤ θ < 100.5 0.0005 0.724
 
 100.5 ≤ θ < 101.5 0.0005 0.718
 
 101.5 ≤ θ < 102.5 0.0005 0.712
 
 102.5 ≤ θ < 103.5 0.0005 0.71
 
 103.5 ≤ θ < 104.5 0.0005 0.704
 
 104.5 ≤ θ < 105.5 0.0005 0.702
 
 105.5 ≤ θ < 106.5 0.0005 0.698
 
 106.5 ≤ θ < 107.5 0.0005 0.695
 
 107.5 ≤ θ < 108.5 0.0005 0.695
 
 108.5 ≤ θ < 109.5 0.0005 0.692
 
 109.5 ≤ θ < 110.5 0.0005 0.689
 
 110.5 ≤ θ < 111.5 0.0005 0.689
 
 111.5 ≤ θ < 112.5 0.0005 0.69
 
 112.5 ≤ θ < 113.5 0.0005 0.686
 
 113.5 ≤ θ < 114.5 0.0005 0.684
 
 114.5 ≤ θ < 115.5 0.0005 0.684
 
 115.5 ≤ θ < 116.5 0.0005 0.682
 
 116.5 ≤ θ < 117.5 0.0005 0.666;
 
 
and
 
 TABLE 2
 
 
 
 
 FILM THICKNESS OF SiN FILM
 
 θ LOWER LIMIT [λ] UPPER LIMIT [λ]
 
 
 
 −84.5 ≤ θ < −83.5 0.0005 0.746
 
 −83.5 ≤ θ < −82.5 0.0005 0.732
 
 −82.5 ≤ θ < −81.5 0.0005 0.736
 
 −81.5 ≤ θ < −80.5 0.0005 0.726
 
 −80.5 ≤ θ < −79.5 0.0005 0.724
 
 −79.5 ≤ θ < −78.5 0.0005 0.718
 
 −78.5 ≤ θ < −77.5 0.0005 0.712
 
 −77.5 ≤ θ < −76.5 0.0005 0.71
 
 −76.5 ≤ θ < −75.5 0.0005 0.704
 
 −75.5 ≤ θ < −74.5 0.0005 0.702
 
 −74.5 ≤ θ < −73.5 0.0005 0.698
 
 −73.5 ≤ θ < −72.5 0.0005 0.695
 
 −72.5 ≤ θ < −71.5 0.0005 0.695
 
 −71.5 ≤ θ < −70.5 0.0005 0.692
 
 −70.5 ≤ θ < −69.5 0.0005 0.689
 
 −69.5 ≤ θ < −68.5 0.0005 0.689
 
 −68.5 ≤ θ < −67.5 0.0005 0.69
 
 −67.5 ≤ θ < −66.5 0.0005 0.686
 
 −66.5 ≤ θ < −65.5 0.0005 0.684
 
 −65.5 ≤ θ < −64.5 0.0005 0.684
 
 −64.5 ≤ θ < −63.5 0.0005 0.682
 
 −63.5 ≤ θ < −62.5 0.0005 0.666.