US 11,942,921 B2
Acoustic wave device
Yasumasa Taniguchi, Nagaokakyo (JP); and Katsuya Daimon, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Jun. 7, 2021, as Appl. No. 17/340,182.
Application 17/340,182 is a continuation of application No. PCT/JP2019/048053, filed on Dec. 9, 2019.
Claims priority of application No. 2018-230836 (JP), filed on Dec. 10, 2018.
Prior Publication US 2021/0297061 A1, Sep. 23, 2021
Int. Cl. H03H 9/145 (2006.01); H03H 9/02 (2006.01); H03H 9/25 (2006.01)
CPC H03H 9/145 (2013.01) [H03H 9/02007 (2013.01); H03H 9/02535 (2013.01); H03H 9/25 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An acoustic wave device comprising:
a piezoelectric layer;
an interdigital transducer (IDT) electrode located on the piezoelectric layer;
a high-acoustic-velocity member positioned on an opposite side of the piezoelectric layer from the IDT electrode such that an acoustic velocity of a bulk wave propagating through the high-acoustic-velocity member is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer;
a low-acoustic-velocity film provided between the high-acoustic-velocity member and the piezoelectric layer such that an acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than the acoustic velocity of the bulk wave propagating through the piezoelectric layer; and
a dielectric film located on the piezoelectric layer so as to cover the IDT electrode; wherein
a Young's modulus of the dielectric film is larger than a Young's modulus of the low-acoustic-velocity film; and
a material of the dielectric film is silicon oxide.