US 12,301,213 B2
Structure and manufacturing method of surface acoustic wave filter with back electrode of piezoelectric layer
Guojun Weng, Shenzhen (CN); and Gongbin Tang, Shenzhen (CN)
Assigned to Shenzhen Newsonic Technologies Co., Ltd., Shenzhen (CN)
Filed by Shenzhen Newsonic Technologies Co., Ltd., Shenzhen (CN)
Filed on Sep. 16, 2022, as Appl. No. 17/933,073.
Prior Publication US 2023/0011477 A1, Jan. 12, 2023
Int. Cl. H03H 9/64 (2006.01); H03H 9/02 (2006.01); H03H 9/145 (2006.01)
CPC H03H 9/64 (2013.01) [H03H 9/02543 (2013.01); H03H 9/145 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A surface acoustic wave (SAW) filter, comprising:
a bottom substrate;
a piezoelectric layer disposed above the bottom substrate, the piezoelectric layer having a bottom surface facing the bottom substrate and a top surface opposite to the bottom surface;
a cavity disposed below the piezoelectric layer;
an interdigital transducer (IDT) disposed on the top surface of the piezoelectric layer;
a back electrode disposed on the bottom surface of the piezoelectric layer, at least a portion of the back electrode being exposed in the cavity;
a first dielectric layer disposed between the piezoelectric layer and the bottom substrate;
a second dielectric layer disposed below the first dielectric layer; and
a third dielectric layer disposed below the second dielectric layer, and including a protruding structure protruding toward the first dielectric layer,
wherein the cavity is surrounded by a double-wall boundary structure constituted by the second dielectric layer and the protruding structure of the third dielectric layer.