Patent ID: 11967946
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. A filter device, comprising:
a substrate having a surface;
at least one piezoelectric layer having front and back surfaces;
a bonding layer formed on the surface of the substrate;
an etch-stop layer sandwiched between the bonding layer and the back surface of the at least one piezoelectric layer, wherein portions of the at least one piezoelectric layer and the etch-stop layer, but not the bonding layer, form two or more diaphragms spanning respective cavities;
a conductor pattern at the at least one piezoelectric layer, the conductor pattern including a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators including a shunt resonator and a series resonator, interleaved fingers of each of the plurality of IDTs disposed on a respective diaphragm of the two or more diaphragms; and
a frequency setting dielectric layer disposed on the front surface of the at least one piezoelectric layer and between the respective interleaved fingers of the IDT of the shunt resonator,
wherein the etch-stop layer is impervious to an etch process used to form the cavities.