초록

A multilayer metal cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device, and a method for forming the cap.

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What is claimed is: 1. A method for forming a multilayer metal cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device comprising: depositing a first cobalt-based metal cap layer over the metal-filled interconnect feature in a

What is claimed is: 1. A method for forming a multilayer metal cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device comprising: depositing a first cobalt-based metal cap layer over the metal-filled interconnect feature in a first electroless deposition process employing a first electroless solution comprising a source of Co ions and a borane-based reducing agent and wherein the first metal cap layer is substantially continuous and has a thickness between about 5 angstroms and about 50 angstroms; and depositing a second cobalt-based metal cap layer over the first metal cap layer in a second electroless deposition process distinct from the first deposition process wherein the second deposition process is electroless and employs a second electroless solution which comprises a source of Co ions and a reducing agent, and which is distinct from, and prepared separately from, the first electroless solution, to thereby form the multilayer metal cap as a permanent component distinct from the metal-filled interconnect feature. 2. The method of claim 1 wherein the metal-filled interconnect feature is a Cu-filled interconnect feature. 3. The method of claim 1 wherein the first cobalt-based metal cap layer has a thickness between about 5 angstroms and about 20 angstroms. 4. The method of claim 1 wherein the first cobalt-based metal cap layer is a cobalt-based alloy selected from the group consisting of Co--W--B, Co--W--B--P, Co--B--P, Co--B, Co--Mo--B, Co--W--Mo--B, and Co--W--Mo--B--P. 5. The method of claim 1 wherein the first cobalt-based metal cap layer is a cobalt-based alloy selected from the group consisting of Co--W--B, Co--W--B--P, Co--B--P, and Co--B. 6. The method of claim 1 wherein the second cobalt-based metal cap layer has a thickness between about 60 angstroms about 100 angstroms. 7. The method of claim 1 wherein the second cobalt-based metal cap layer has a thickness greater than about 100 angstroms. 8. The method of claim 1 wherein the second cobalt-based metal cap layer has a thickness between about 100 angstroms and about 300 angstroms. 9. The method of claim 1 wherein the second cobalt-based metal cap layer is a cobalt-based alloy selected from the group consisting of Co--W--P, Co--W--B, Co--W--B--P, Co--B--P, Co--B, Co--Mo--B, Co--W--Mo--B, Co--W--Mo--B--P, and Co--Mo--P. 10. The method of claim 1 further comprising the step of depositing a discontinuous, substantially uncoalesced Co seed onto the metal-filled interconnect feature prior to depositing the first cobalt-based metal cap layer. 11. The method of claim 1 further comprising the step of depositing a third metal cap layer over the second cobalt-based metal cap layer in a third deposition process distinct from the second deposition process. 12. A method for forming a multilayer metal cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device comprising: depositing a first metal cap layer over the metal-filled interconnect feature in a first noble metal immersion deposition process employing a noble metal immersion solution comprising a source of noble metal ions; depositing a second cobalt-based metal cap layer over the first metal cap layer in a first electroless deposition process distinct from the first deposition process, wherein the first electroless deposition process employs a first electroless deposition solution comprising a source of Co ions and a reducing agent; and depositing a third cobalt-based metal cap layer over the second metal cap layer in a second electroless deposition process distinct from the first electroless deposition process, wherein the second electroless deposition process employs a second electroless deposition solution comprising a source of Co ions and a reducing agent, which is distinct from, and prepared separately from, the second electroless deposition solution, to thereby form the multilayer metal cap as a permanent component distinct from the metal-filled interconnect feature. 13. The method of claim 12 wherein the metal-filled interconnect feature is a Cu-filled interconnect feature. 14. The process of claim 12 wherein depositing the first metal cap layer comprises depositing a Pd layer which is discontinuous and substantially uncoalesced, and functions as a seed layer for the second deposition process. 15. The process of claim 12 wherein depositing the first metal cap layer comprises depositing a Pd layer which is substantially continuous and has a thickness between about 5 and about 50 angstroms. 16. The method of claim 12 wherein the second cobalt-based metal cap layer has a thickness between about 5 angstroms and about 50 angstroms. 17. The method of claim 12 wherein the second cobalt-based metal cap layer has a thickness between about 5 angstroms and about 20 angstroms. 18. The method of claim 12 wherein the second cobalt-based metal cap layer has a thickness between about 60 angstroms about 100 angstroms. 19. The method of claim 12 wherein the second cobalt-based metal cap layer has a thickness greater than about 100 angstroms. 20. The method of claim 12 wherein the second cobalt-based metal cap layer has a thickness between about 100 angstroms and about 300 angstroms. 21. The method of claim 12 wherein the third cobalt-based metal cap layer has a thickness between about 60 angstroms about 100 angstroms. 22. The method of claim 12 wherein the third cobalt-based metal cap layer has a thickness greater than about 100 angstroms. 23. The method of claim 12 wherein the third cobalt-based metal cap layer has a thickness between about 100 angstroms and about 300 angstroms. 24. The method of claim 12 further comprising depositing a fourth metal cap layer over the third cobalt-based metal cap layer in a third electroless deposition process distinct from the second electroless deposition process.