Capping of metal interconnects in integrated circuit electronic devices

• US 20050275100A1
• Filed: 06/14/2004
• Published: 12/15/2005
• Est. Priority Date: 06/14/2004
• Status: Active Grant

• Current Assignee: MacDermid Enthone Inc. (Element Solutions Inc)
• Original Assignee: Enthone Incorporated (Element Solutions Inc)
• Inventors: Chen, Qingyun, Hurtubise, Richard, Yakobson, Eric, Witt, Christian
• Granted Patent: US 7,268,074 B2
• Time in Patent Office: Days
• US Class Current: 257/748
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76849 the layer being positioned on top of the main fill metal
• CPC Class Codes: H01L 2224/05006 Dual damascene structure
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01023 Vanadium [V]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01042 Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01044 Ruthenium [Ru]
• CPC Class Codes: H01L 2924/01045 Rhodium [Rh]
• CPC Class Codes: H01L 2924/01047 Silver [Ag]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01076 : Osmium [Os]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01084 : Polonium [Po]
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15747 : Copper [Cu] as principal constituent
• CPC Class Codes: H05K 2203/072 : Electroless plating, e.g. finish plating or initial plating
• CPC Class Codes: H05K 2203/1476 : Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 3/107 : by filling grooves in the support with conductive material H05K3/045, H05K3/101, H05K3/1258 and H05K3/465 take precedence
• CPC Class Codes: H05K 3/244 : Finish plating of conductors, especially of copper conductors, e.g. for pads or lands selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3457, e.g. by plating H05K3/3473

Abstract

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.

Claims

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 metal cap layer over the metal-filled interconnect feature in a first deposition process which constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent; and

depositing a second metal cap layer over the first metal cap layer in a second deposition process distinct from the first deposition process 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 second deposition process is an electroless deposition process; and

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process.

3. The method of claim 1 wherein the first deposition process employs a first electroless solution comprising a source of Co ions and a borane-based reducing agent.

4. The method of claim 1 wherein the first deposition process is self-aligning in that the first metal cap layer is selectively deposited onto the metal-filled interconnect and the second deposition process is self-aligning in that the second metal cap layer is selectively deposited onto the first metal cap layer.

5. The method of claim 1 wherein the metal-filled interconnect feature is a Cu-filled interconnect feature, and the first metal cap layer comprises a metal or metal alloy which is substantially immiscible with Cu.

6. The method of claim 1 wherein:

the first deposition process employs a first electroless solution comprising a source of Co ions and a borane-based reducing agent;

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.

7. The method of claim 1 wherein:

the first deposition process employs a first electroless solution comprising a source of Co ions and a borane-based reducing agent;

the second deposition process is electroless and employs a second electroless solution which comprises a source of Ni ions and a reducing agent.

8. The method of claim 1 wherein:

the first deposition process employs a first electroless solution comprising a source of Co ions and a borane-based reducing agent;

the second deposition process is electroless and employs a second electroless solution which comprises a source of Ni ions and a reducing agent.

9. The method of claim 1 wherein the second deposition process is an electroless deposition process distinct from the first deposition process with respect to a parameter selected from among pH, deposition temperature, liquid flow rate, bath agitation, substrate rotation, and combinations thereof.

10. The method of claim 1 wherein the first metal cap layer is substantially continuous and has a thickness between about 5 and about 50 angstroms.

11. The method of claim 1 wherein:

the first metal cap layer is substantially continuous and has a thickness between about 5 and about 50 angstroms; and

the second metal cap layer has a thickness greater than about 100 angstroms.

12. The method of claim 1 wherein the first metal cap layer is discontinuous and substantially uncoalesced.

13. The method of claim 1 comprising discontinuing deposition between the first deposition process and the second deposition process.

14. The method of claim 1 wherein the first metal cap layer and second metal cap layer comprise Co-based alloys.

15. The method of claim 1 wherein the first metal cap layer comprises a Co-based alloy and the second metal cap layer comprises a Ni-based alloy.

16. The method of claim 1 further comprising depositing a third metal cap layer over the second metal cap layer in a third deposition process distinct from the second deposition process.

17. The method of claim 1 comprising depositing a discontinuous, substantially uncoalesced Co seed onto the metal-filled interconnect feature prior to depositing the first metal cap layer.

18. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process; and

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process.

19. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process which is self-aligning in that the second metal cap layer is selectively deposited on the first metal cap layer;

the first deposition process is self-aligning in that the second metal cap layer is selectively deposited on the first metal cap layer; and

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process.

20. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

21. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy, is discontinuous and substantially uncoalesced, and has a thickness between about 5 and about 50 angstroms.

22. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the second metal cap layer comprises a Ni-based alloy and has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

23. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the second metal cap layer comprises a Ni-based alloy and has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy, is discontinuous and substantially uncoalesced, and has a thickness between about 5 and about 50 angstroms.

24. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the first electroless solution composition comprises a borane-based compound as its primary reducing agent;

the first second electroless solution composition comprises a non-borane-based compound as its primary reducing agent;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

25. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the first electroless solution composition comprises a borane-based compound as its primary reducing agent;

the first second electroless solution composition comprises a non-borane-based compound as its primary reducing agent;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness between about 5 and about 50 angstroms.

26. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the first electroless solution composition comprises a borane-based compound as its primary reducing agent;

the second electroless solution composition comprises a hypophosphite compound as its primary reducing agent;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

27. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process;

the first deposition process is distinct from the second deposition process in that the first deposition process employs a first electroless solution which has a first solution composition distinct from, and prepared separately from, a second electroless solution having a second solution composition employed in the second deposition process;

the first electroless solution composition comprises a borane-based compound as a primary reducing agent;

the second electroless solution composition comprises a hypophosphite compound as a primary reducing agent;

the second metal cap layer has a thickness greater than about 100 angstroms; and

the first metal cap layer comprises a Co-based alloy and has a thickness between about 5 and about 50 angstroms.

51. The method of claim 1 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the third deposition process is an electroless deposition process;

the second deposition process is distinct from the third deposition process in that the second deposition process employs a second electroless solution which has a second solution composition distinct from, and prepared separately from, a third electroless solution having a third solution composition employed in the third deposition process;

the third metal cap layer has a thickness greater than about 100 angstroms; and

the second metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

28. 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 deposition process which constitutes noble metal immersion deposition from a solution comprising a source of noble metal ions;

depositing a second metal cap layer over the first metal cap layer in a second deposition process distinct from the first deposition process; and

depositing a third metal cap layer over the second metal cap layer in a third deposition process distinct from the second deposition process.

29. The method of claim 28 wherein:

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

30. The method of claim 28 wherein:

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent; and

depositing the third metal cap layer over the second metal cap layer in the third deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

31. The process of claim 28 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.

32. The process of claim 28 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; and

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

33. The process of claim 28 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;

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent; and

depositing the third metal cap layer over the second metal cap layer in the third deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

34. The process of claim 28 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.

35. The process of claim 28 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; and

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

36. The process of claim 28 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;

depositing the second metal cap layer over the first metal cap layer in the second deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent; and

depositing the third metal cap layer over the second metal cap layer in the third deposition process constitutes electroless metal deposition from an electroless bath comprising a source of metal ions and a reducing agent.

37. The method of claim 28 wherein:

the third deposition process is an electroless deposition process; and

the second deposition process is distinct from the third deposition process in that the second deposition process employs a second electroless solution which has a second solution composition distinct from, and prepared separately from, a third electroless solution having a third solution composition employed in the third deposition process.

38. The method of claim 28 wherein the second deposition process employs an electroless solution comprising a source of Co ions and a reducing agent.

39. The method of claim 28 wherein the second deposition process is self-aligning in that the second metal cap layer is selectively deposited onto the first metal cap layer and the third deposition process is self-aligning in that the third metal cap layer is selectively deposited onto the second metal cap layer.

40. The method of claim 28 wherein the metal-filled interconnect feature is a Cu-filled interconnect feature, and the second metal cap layer comprises a metal or metal alloy which is substantially immiscible with Cu.

41. The method of claim 28 wherein:

the second deposition process employs a second electroless solution comprising a source of Co ions and a reducing agent;

the third deposition process is electroless and employs a third electroless solution which comprises a source of Co ions and a reducing agent, and which is distinct from, and prepared separately from, the second electroless solution.

42. The method of claim 28 wherein:

the second deposition process employs a second electroless solution comprising a source of Co ions and a reducing agent;

the third deposition process is electroless and employs a third electroless solution which comprises a source of Ni ions and a reducing agent.

43. The method of claim 28 wherein the third deposition process is an electroless deposition process distinct from the second deposition process with respect to a parameter selected from between pH and deposition temperature.

44. The method of claim 28 wherein:

the first metal cap layer is substantially continuous and has a thickness between about 5 and about 50 angstroms; and

the second metal cap layer has a thickness greater than about 100 angstroms.

45. The method of claim 28 comprising discontinuing deposition between the first deposition process and the second deposition process, and between the second deposition process and the third deposition process.

46. The method of claim 28 wherein the second metal cap layer and third metal cap layer comprise Co-based alloys.

47. The method of claim 28 wherein the second metal cap layer comprises a Co-based alloy and the third metal cap layer comprises a Ni-based alloy.

48. The method of claim 28 further comprising depositing a fourth metal cap layer over the third metal cap layer in a fourth deposition process distinct from the third deposition process.

49. The method of claim 28 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the third deposition process is an electroless deposition process; and

the second deposition process is distinct from the third deposition process in that the second deposition process employs a second electroless solution which has a second solution composition distinct from, and prepared separately from, a third electroless solution having a third solution composition employed in the third deposition process.

50. The method of claim 28 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second deposition process is an electroless deposition process which is self-aligning in that the second metal cap layer is selectively deposited on the first metal cap layer;

the third deposition process is self-aligning in that the third metal cap layer is selectively deposited on the second metal cap layer; and

the second deposition process is distinct from the third deposition process in that the second deposition process employs a second electroless solution which has a second solution composition distinct from, and prepared separately from, a third electroless solution having a third solution composition employed in the third deposition process.

52. The method of claim 28 wherein:

the metal-filled interconnect feature is a Cu-filled interconnect feature;

the second and third deposition processes are electroless deposition processes;

the second deposition process is distinct from the third deposition process in that the second deposition process employs a second electroless solution which has a second solution composition distinct from, and prepared separately from, a third electroless solution having a third solution composition employed in the third deposition process;

the third metal cap layer comprises a Ni-based alloy and has a thickness greater than about 100 angstroms; and

the second metal cap layer comprises a Co-based alloy and has a thickness greater than about 100 angstroms.

53. 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 catalytic first metal cap layer over the metal-filled interconnect feature in a first deposition process; and

depositing a second metal cap layer over the first metal cap layer in a second deposition process distinct from the first deposition process, wherein the second deposition process comprises autocatalytic deposition and deposition catalyzed by the first metal cap layer.

54. The method of claim 53 wherein the first deposition process comprises noble metal immersion deposition from a solution comprising a source of noble metal ions.

55. The method of claim 53 wherein the first deposition process comprises Pd immersion deposition from a solution comprising a source of Pd ions, and the second deposition process comprises electroless deposition of a Co-based layer employing a hypophosphite based reducing agent and a borane-based reducing agent.

56. A multilayer cap over a metal-filled interconnect feature in a dielectric layer for incorporation into a multilayer integrated circuit device comprising:

a first metal cap layer over the metal-filled interconnect feature; and

a second metal cap layer over the first metal cap layer, wherein the first and second metal cap layers are components of the multilayer metal cap which constitutes a permanent component distinct from the metal interconnect feature.

57. The multilayer cap of claim 56 wherein:

the first metal cap layer comprises a metal or metal alloy which is substantially immiscible with the metal-filled interconnect feature; and

the first metal cap layer and second metal cap layer comprise metals or metal alloys which are substantially immiscible with the dielectric layer.

58. The multilayer cap of claim 56 wherein the first metal cap layer comprises Co or a Co-based alloy.

59. The multilayer cap of claim 56 wherein:

the first metal cap layer comprises Co or a Co-based alloy; and

the second metal cap layer comprises Co or a Co-based alloy.

60. The multilayer cap of claim 56 wherein:

the first metal cap layer comprises Co or a Co-based alloy; and

the second metal cap layer comprises Ni or a Ni-based alloy.

61. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness greater than about 100 angstroms; and

the second metal cap layer has a thickness greater than about 100 angstroms.

62. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness between about 5 and about 50 angstroms; and

the second metal cap layer has a thickness greater than about 100.

63. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness greater than about 100 angstroms and comprises Co or a Co-based alloy; and

the second metal cap layer has a thickness greater than about 100 angstroms and comprises Co or a Co-based alloy.

64. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness greater than about 100 angstroms and comprises Co or a Co-based alloy; and

the second metal cap layer has a thickness greater than about 100 angstroms and comprises Ni or a Ni-based alloy.

65. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness between about 5 and about 50 angstroms and comprises Co or a Co-based alloy; and

the second metal cap layer has a thickness greater than about 100 angstroms and comprises Co or a Co-based alloy.

66. The multilayer cap of claim 56 wherein:

the first metal cap layer has a thickness between about 5 and about 50 angstroms and comprises Co or a Co-based alloy; and

the second metal cap layer has a thickness greater than about 100 angstroms and comprises Ni or a Ni-based alloy.

67. The multilayer cap of claim 56 wherein there is a discontinuous, substantially uncoalesced metal seed layer between the first metal cap layer and the metal-filled interconnect.