Solidly-mounted transversely-excited film bulk acoustic resonator with recessed interdigital transducer fingers using rotated y-x cut lithium niobate
AssigneeMurata Manufacturing Co., Ltd.
InventorsVentsislav Yantchev, Viktor Plesski, Bryant Garcia
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Abstract
Acoustic resonator devices, filters, and methods are disclosed. An acoustic resonator includes a substrate, a lithium niobate plate having front and back surfaces, wherein Euler angles of the lithium niobate plate are [0°, β, 0°], where β is greater than or equal to 0° and less than or equal to 60°, and an acoustic Bragg reflector between the surface of the substrate and the back surface of the lithium niobate plate. An interdigital transducer (IDT) is formed on the front surface of the piezoelectric plate. At least one finger of the IDT is disposed in a groove in the lithium niobate plate.
Claims21
An acoustic resonator device comprising:
- a substrate having a surface;
- a lithium niobate plate, wherein Euler angles of the lithium niobate plate are [0°, β, 0° ], where β is greater than or equal to 0° and less than or equal to 60°;
- an acoustic Bragg reflector between the surface of the substrate and the lithium niobate plate;
- and
- an interdigital transducer (IDT) at the lithium niobate plate, wherein at least one finger of the IDT extends in a groove in the lithium niobate plate,
- wherein the groove has a depth in the lithium niobate plate that is less than or equal to a thickness of the at least one finger of the IDT.
A filter device, comprising:
- a substrate;
- a lithium niobate plate, wherein Euler angles of the lithium niobate plate are [0°, β, 0° ], where β is greater than or equal to 0° and less than or equal to 60°;
- an acoustic Bragg reflector between the substrate and the lithium niobate plate;
- and
- a conductor pattern at the lithium niobate plate, the conductor pattern including a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators that each have interleaved fingers at the lithium niobate plate,
- wherein at least one finger of at least one of the plurality of IDTs extends in a groove in the lithium niobate plate, and
- wherein the groove has a depth in the lithium niobate plate that is less than or equal to a thickness of the at least one finger.
A method of fabricating an acoustic resonator device, comprising:
- forming an acoustic Bragg reflector by depositing material layers on one or both of a surface of a device substrate and a lithium niobate plate attached to a sacrificial substrate, wherein Euler angles of the lithium niobate plate are [0°, β, 0° ], where β is greater than or equal to 0° and less than or equal to 60°;
- bonding the lithium niobate plate to the device substrate such that layers of the acoustic Bragg reflector are between the lithium niobate plate and the surface of the device substrate;
- removing the sacrificial substrate to expose the lithium niobate plate;
- and
- forming an interdigital transducer (IDT) at the lithium niobate, wherein at least one finger of the IDT extends in a groove in the lithium niobate plate,
- wherein the groove has a depth in the lithium niobate plate that is less than or equal to a thickness of the at least one finger of the IDT.
Dependencies are inferred from the claim text.