US 12,249,972 B2
Acoustic wave resonator, filter, and multiplexer
Shodai Harai, Tokyo (JP)
Assigned to TAIYO YUDEN CO., LTD., Tokyo (JP)
Filed by TAIYO YUDEN CO., LTD., Tokyo (JP)
Filed on Apr. 5, 2022, as Appl. No. 17/713,590.
Claims priority of application No. 2021-077435 (JP), filed on Apr. 30, 2021.
Prior Publication US 2022/0352871 A1, Nov. 3, 2022
Int. Cl. H03H 9/02 (2006.01); H03H 9/145 (2006.01); H03H 9/25 (2006.01); H03H 9/64 (2006.01); H03H 9/72 (2006.01)
CPC H03H 9/02818 (2013.01) [H03H 9/145 (2013.01); H03H 9/25 (2013.01); H03H 9/6483 (2013.01); H03H 9/72 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An acoustic wave resonator comprising:
a piezoelectric substrate;
a pair of comb-shaped electrodes provided on the piezoelectric substrate, each of the comb-shaped electrodes including electrode fingers and a bus bar to which the electrode fingers are coupled, an acoustic velocity of an acoustic wave propagating through a gap region being equal to or greater than 0.98 times an acoustic velocity of an acoustic wave propagating through an edge region and equal to or less than 1.02 times the acoustic velocity of the acoustic wave propagating through the edge region, the gap region being a first region of a region located between tips of the electrode fingers of one of the comb-shaped electrodes and the bus bar of the other of the comb-shaped electrodes, the first region being provided with no metal film electrically connected to the bus bar of the other of the comb-shaped electrodes, the edge region being a region located in an edge in an extension direction of the electrode fingers in an overlap region, the overlap region being a region where the electrode fingers of the one of the comb-shaped electrodes and the electrode fingers of the other of the comb-shaped electrodes overlap; and
an additional film that is provided over the piezoelectric substrate from the edge region to the gap region and is not provided in a center region that is a region located further in than the edge region in the overlap region,
wherein in the pair of the comb-shaped electrodes, the acoustic velocity of the acoustic wave propagating through the edge region and the acoustic velocity of the acoustic wave propagating through the gap region are lower than an acoustic velocity of an acoustic wave propagating through the center region, and an acoustic velocity of an acoustic wave propagating through a bus bar region is higher than the acoustic velocity of the acoustic wave propagating through the center region, the bus bar region being a region where the bus bar is located.