Inexpensive electrode materials to facilitate rutile phase titanium oxide
This disclosure provides a method of fabricating a semiconductor stack and associated device, such as a capacitor and DRAM cell. In particular, a bottom electrode has a material selected for lattice matching characteristics. This material may be created from a relatively inexpensive metal oxide which is processed to adopt a conductive, but difficult-to-produce oxide state, with specific crystalline form; to provide one example, specific materials are disclosed that are compatible with the growth of rutile phase titanium dioxide (TiO 2 ) for use as a dielectric, thereby leading to predictable and reproducible higher dielectric constant and lower effective oxide thickness and, thus, greater part density at lower cost.
1. A method of fabricating a bottom electrode layer for use with a metal-insulator-metal assembly, the method comprising:
preparing a substrate,
wherein the preparing comprises an ozone scrubbing process, and
wherein a surface roughness of the substrate increases during the ozone scrubbing process;
fabricating a conductive layer on the substrate,
wherein the conductive layer comprises a nitride;
depositing an interface layer over the conductive laver,
wherein a thickness of the interface layer is less than a thickness of the conductive layer, and
wherein the interface layer comprises a conductive material oxide in a crystalline form; and
depositing a dielectric layer on the interface layer,
wherein the dielectric layer comprises titanium oxide having a rutile phase, and
wherein a lattice structure of a top surface of the interface layer is compatible with the rutile phase of titanium oxide of the dielectric layer.
2. A method as in claim 1 wherein the substrate comprises silicon.
3. A method as in claim 1 wherein fabricating the interface layer comprises chemical vapor deposition or atomic layer deposition.
4. A method as in claim 3 wherein the interface layer comprises MoO 2 .
5. A method as in claim 4 further comprising performing rapid thermal nitridazationof the interface layer thereby crystallizing the MoO 2 layer.
6. A method as in claim 1 wherein fabricating the interface layer comprises fabricating a non-conductive layer and treating the non-conductive layer to convert the non-conductive layer into the conductive metal oxide.
7. A method as in claim 6 wherein the non-conductive layer comprises MoO 3 and wherein the treatment of the non-conductive layer comprises a reducing anneal.
8. A method as in claim 6 wherein the non-conductive layer comprises a metal nitride and wherein the treatment of the non-conductive layer comprises oxidation.
9. A method as in claim 8 wherein the metal nitride comprises a molybdenum nitride.
10. A method of fabricating a bottom electrode layer for use with a metal-insulator-metal assembly, the method comprising:
preparing a substrate; and
fabricating a conductive layer on the substrate,
wherein the conductive layer comprises a nitride;
fabricating an interface layer on the conductive layer,
wherein a thickness of the interface layer is less than a thickness of the conductive layer, and
wherein the interface layer comprises a conductive material oxide in a crystalline form; and
fabricating a dielectric layer on the interface layer,
wherein the dielectric layer comprises titanium oxide having a rutile phase, and
wherein a lattice structure of the top surface of the interface layer is compatible with the rutile phase of titanium oxide of the dielectric layer.
11. A method as in claim 10 wherein the substrate comprises silicon.
12. A method as in claim 11 wherein preparing the substrate comprises an ozone scrubbing process.
13. A method as in claim 10 wherein fabricating the interface layer on comprises chemical vapor deposition or atomic layer deposition.
14. A method as in claim 13 wherein the interface layer comprises MoO 2 .
15. A method as in claim 14 further comprising performing rapid thermal nitridazation of the interface layer thereby crystallizing MoO 2 of the interface layer.
16. A method as in claim 10 wherein fabricating the interface layer comprises fabricating a non-conductive layer and treating the non-conductive layer to convert the non-conductive layer into the conductive metal oxide.
17. A method as in claim 16 wherein the non-conductive layer comprises MoO 3 and wherein the treatment of the non-conductive layer comprises a reducing anneal.
18. A method as in claim 16 wherein the non-conductive layer comprises a metal nitride and wherein the treatment of the non-conductive layer comprises oxidation.
19. A method as in claim 18 wherein the metal nitride comprises a molybdenum nitride.
20. A method as in claim 10 further comprises in-situ modification of the interface layer.