US 12,081,198 B2
Transversely-excited film bulk acoustic resonator with a back-side dielectric layer and an etch-stop layer
Patrick Turner, San Bruno, CA (US)
Assigned to MURATA MANUFACTURING CO., LTD., Nagaokakyo (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Dec. 8, 2020, as Appl. No. 17/115,767.
Application 17/115,767 is a continuation of application No. 16/933,224, filed on Jul. 20, 2020, granted, now 10,911,023.
Claims priority of provisional application 62/993,586, filed on Mar. 23, 2020.
Claims priority of provisional application 62/978,133, filed on Feb. 18, 2020.
Prior Publication US 2021/0257991 A1, Aug. 19, 2021
Int. Cl. H03H 9/56 (2006.01); H03H 3/02 (2006.01); H03H 9/02 (2006.01); H03H 9/13 (2006.01); H03H 9/17 (2006.01); H10N 30/072 (2023.01); H10N 30/87 (2023.01)
CPC H03H 9/568 (2013.01) [H03H 3/02 (2013.01); H03H 9/02015 (2013.01); H03H 9/02031 (2013.01); H03H 9/02062 (2013.01); H03H 9/02228 (2013.01); H03H 9/132 (2013.01); H03H 9/174 (2013.01); H03H 9/176 (2013.01); H03H 9/562 (2013.01); H03H 9/564 (2013.01); H10N 30/072 (2023.02); H03H 2003/023 (2013.01); H03H 9/02039 (2013.01); H10N 30/877 (2023.02)] 13 Claims
OG exemplary drawing
 
8. A filter device comprising:
a plurality of bulk acoustic wave resonators including a shunt resonator and a series resonator, wherein each of the shunt and series resonators comprises:
a substrate including a plurality of materials and a cavity disposed therein;
a piezoelectric layer that is attached to the substrate by a dielectric layer;
an etch-stop layer sandwiched between the substrate and the dielectric layer; and
a conductor pattern on the piezoelectric layer and including an interdigital transducer (IDT) that includes interleaved fingers disposed on a portion of the respective piezoelectric layer that is over the cavity; and
wherein an additional dielectric layer is disposed on the piezoelectric layer of the shunt resonator and between the interleaved fingers of the IDT of the shunt resonator,
wherein the etch-stop layer is impervious to an etch process used to form the respective cavity of each of the shunt and series resonators, and
wherein a sum of a thickness of the dielectric layer and the additional dielectric layer of the shunt resonator is greater than 35% of a thickness of the piezoelectric layer of the shunt resonators.