US 12,395,151 B2
Acoustic wave device
Akira Michigami, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Nov. 16, 2022, as Appl. No. 17/987,927.
Application 17/987,927 is a continuation of application No. PCT/JP2021/020184, filed on May 27, 2021.
Claims priority of application No. 2020-093431 (JP), filed on May 28, 2020.
Prior Publication US 2023/0084908 A1, Mar. 16, 2023
Int. Cl. H03H 9/25 (2006.01); H03H 9/02 (2006.01); H03H 9/13 (2006.01)
CPC H03H 9/25 (2013.01) [H03H 9/02007 (2013.01); H03H 9/02992 (2013.01); H03H 9/131 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An acoustic wave device comprising:
a support substrate;
a low-acoustic-velocity film on the support substrate;
a piezoelectric layer on the low-acoustic-velocity film;
an IDT electrode on the piezoelectric layer; and
a high-acoustic-velocity film between the support substrate and the low-acoustic-velocity film; wherein
an acoustic velocity of a bulk wave propagating through the low-acoustic-velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer;
an acoustic velocity of a bulk wave propagating though the high-acoustic-velocity film is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer;
adhesion between the low-acoustic-velocity film and the support substrate is higher than adhesion between the high-acoustic-velocity film and the support substrate; and
the high-acoustic-velocity film is between a portion of the support substrate and a portion of the low-acoustic-velocity film, and a portion of the low-acoustic-velocity film and a portion of the support substrate contact each other.