Acoustic resonator structure with inclined C-axis piezoelectric bulk and crystalline seed layers
Systems and methods for growing hexagonal crystal structure piezoelectric material with a c-axis that is tilted (e.g., 25 to 50 degrees) relative to normal of a face of a substrate are provided. A deposition system includes a linear sputtering apparatus, a translatable multi-aperture collimator, and a translatable substrate table arranged to hold multiple substrates, with the substrate table and/or the collimator being electrically biased to a nonzero potential. An enclosure includes first and second deposition stations each including a linear sputtering apparatus, a collimator, and a deposition aperture.
1. An acoustic resonator structure comprising:
a substrate;
at least one first electrode structure supported by the substrate;
a crystalline seed layer arranged over the substrate and the at least one first electrode structure;
a hexagonal crystal structure piezoelectric material bulk layer arranged over the crystalline seed layer, the bulk layer covering an area of the substrate; and
at least one second electrode structure arranged over at least a portion of the hexagonal crystal structure piezoelectric material bulk layer;
wherein at least 75% of the hexagonal crystal structure piezoelectric material bulk layer comprises a c-axis having an orientation distribution in a range of from 25 degrees to 50 degrees relative to normal of a face of the substrate, and wherein the c-axis orientation distribution is substantially uniform over the area covered by the bulk layer.
2. The acoustic resonator structure of claim 1 , wherein the crystalline seed layer is compositionally matched to the hexagonal crystal structure piezoelectric material bulk layer.
3. The acoustic resonator structure of claim 1 , wherein a thickness of the crystalline seed layer is no greater than about 20% of a combined thickness of the hexagonal crystal structure piezoelectric material bulk layer and the crystalline seed layer.
4. The acoustic resonator structure of claim 1 , wherein the crystalline seed layer comprises a thickness in a range of from about 500 Angstroms to about 2,000 Angstroms.
5. The acoustic resonator structure of claim 1 , wherein at least 50% of the crystalline seed layer comprises a c-axis having an orientation distribution predominantly in a range of from 0 degrees to 35 degrees relative to normal of a face of the substrate.
6. The acoustic resonator structure of claim 1 , wherein the hexagonal crystal structure piezoelectric material bulk layer comprises a thickness in a range of from about 4,000 Angstroms to about 26,000 Angstroms.
7. The acoustic resonator structure of claim 1 , wherein the substrate comprises a semiconductor material.
8. The acoustic resonator structure of claim 1 , further comprising an acoustic reflector structure arranged between the substrate and the at least one first electrode structure.
9. The acoustic resonator structure of claim 8 , wherein the substrate is arranged between a backside surface and the acoustic reflector structure, and the backside surface comprises a roughened surface configured to reduce or eliminate backside acoustic reflection.
10. The acoustic resonator structure of claim 1 , wherein the substrate defines a recess, a support layer is arranged over the recess, and the support layer is arranged between the substrate and at least a portion of the at least one first electrode structure.
11. The acoustic resonator structure of claim 1 , wherein at least 90% of the hexagonal crystal structure piezoelectric material bulk layer comprises a c-axis having an orientation distribution in a range of from 25 degrees to 50 degrees relative to normal of a face of the substrate.
12. The acoustic resonator structure of claim 1 , wherein at least 75% of the hexagonal crystal structure piezoelectric material bulk layer comprises a c-axis having an orientation distribution in a range of from 30 degrees to 40 degrees relative to normal of a face of the substrate.
13. The acoustic resonator structure of claim 1 , wherein less than about 3 percent of the c-axis orientation distribution of the hexagonal crystal structure piezoelectric material bulk layer is in a range of from 0 degrees to 15 degrees relative to normal of a face of the substrate.
14. The acoustic resonator structure of claim 1 , wherein the substrate comprises a diameter of at least about 50 mm, and the hexagonal crystal structure piezoelectric material bulk layer covers at least about 50% of a face of the substrate.
15. The acoustic resonator structure of claim 1 , wherein the substrate comprises a diameter of at least about 100 mm, and the hexagonal crystal structure piezoelectric material bulk layer covers at least about 50% of a face of the substrate.
16. The acoustic resonator structure of claim 1 , wherein the hexagonal crystal structure piezoelectric material bulk layer comprises aluminum nitride or zinc oxide.
17. An acoustic resonator structure comprising:
a substrate;
at least one first electrode structure supported by the substrate;
a crystalline seed layer arranged over the substrate and the at least one first electrode structure;
a hexagonal crystal structure piezoelectric material bulk layer arranged over the crystalline seed layer; and
at least one second electrode structure arranged over at least a portion of the hexagonal crystal structure piezoelectric material bulk layer;
wherein at least 50% of the hexagonal crystal structure piezoelectric material bulk layer comprises a c-axis having an orientation distribution in a range of from 25 degrees to 50 degrees relative to normal of a face of the substrate,
wherein:
the at least one first electrode structure comprises a plurality of first electrode structures;
the at least one second electrode structure comprises a plurality of second electrode structures;
a first portion of the acoustic resonator structure comprises a first bulk acoustic wave resonator device including a first active region arranged between one first electrode structure of the plurality of first electrode structures and one second electrode structure of the plurality of second electrode structures; and
a second portion of the acoustic resonator structure comprises a second bulk acoustic wave resonator device including a second active region arranged between another first electrode structure of the plurality of first electrode structures and another second electrode structure of the plurality of second electrode structures.
18. A bulk acoustic wave resonator chip derived from the acoustic resonator structure of claim 17 .
19. A sensor or microfluidic device incorporating the bulk acoustic wave resonator chip of claim 18 .
20. An acoustic resonator structure comprising:
a substrate;
at least one first electrode structure supported by the substrate;
a crystalline seed layer arranged over the substrate and the at least one first electrode structure;
a hexagonal crystal structure piezoelectric material bulk layer arranged over the crystalline seed layer, the bulk layer having been applied using a deposition system comprising a translatable substrate table and a translatable collimator; and
at least one second electrode structure arranged over at least a portion of the hexagonal crystal structure piezoelectric material bulk layer;
wherein at least 50% of the hexagonal crystal structure piezoelectric material bulk layer comprises a c-axis having an orientation distribution predominantly in a range of from 25 degrees to 50 degrees relative to normal of a face of the substrate.