Enhanced diffusion barrier for interconnect structures

• US 8,420,531 B2
• Filed: 06/21/2011
• Issued: 04/16/2013
• Est. Priority Date: 06/21/2011
• Status: Active Grant

• Current Assignee: Alsephina Innovations Inc. (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: International Business Machines Corporation
• Inventors: Yang, Chih-Chao, Edelstein, Daniel C., Molis, Steven E.
• Primary Examiner(s): Garber, Charles
• Assistant Examiner(s): Patel, Reema
• Application Number:
  US13/164,929
• Publication Number:
  US 20120326311A1
• Time in Patent Office: 665 Days
• Field of Search: 438/627, 438/629, 438/637, 438/642, 438/643
• US Class Current: 438/643
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/76826 by contacting the layer with gases, liquids or plasmas
• CPC Class Codes: H01L 21/76828 thermal treatment
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76855 After-treatment introducing at least one additional element into the layer
• CPC Class Codes: H01L 21/76867 characterized by methods of formation other than PVD, CVD or deposition from a liquids PVD H01L21/2855; CVD H01L21/28556; deposition from liquids H01L21/288
• CPC Class Codes: H01L 23/52 Arrangements for conducting electric current within the device in operation from one component to another , i.e. interconnections, e.g. wires, lead frames optical interconnections G02B6/00
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Alternative methods of fabricating an interconnect structure in which an enhanced diffusion barrier including an in-situ formed metal nitride liner formed between an interconnect dielectric material and an overlying metal diffusion barrier liner are provided. In one embodiment, the method includes forming at least one opening into an interconnect dielectric material. A nitrogen enriched dielectric surface layer is formed within exposed surfaces of the interconnect dielectric material utilizing thermal nitridation. A metal diffusion barrier liner is formed on the nitrogen enriched dielectric surface. During and/or after the formation of the metal diffusion barrier liner, a metal nitride liner forms in-situ in a lower region of the metal diffusion barrier liner. A conductive material is then formed on the metal diffusion barrier liner. The conductive material, the metal diffusion barrier liner and the metal nitride liner that are located outside of the at least one opening are removed to provide a planarized conductive material, a planarized metal diffusion barrier liner and a planarized metal nitride liner, each of which includes an upper surface that is co-planar with the nitrogen enriched dielectric surface layer of the interconnect dielectric material.

Claims

1. A method of forming an interconnect structure, said method comprising:

forming at least one opening into an interconnect dielectric material;

forming a nitrogen enriched dielectric surface layer within exposed surfaces of said interconnect dielectric material, wherein said nitrogen enriched dielectric surface layer is formed by thermal nitridation in a non-plasma nitrogen-containing ambient, said nitrogen enriched dielectric surface layer has a higher nitrogen content than a remaining portion of the interconnect dielectric material;

forming a metal diffusion barrier liner on said nitrogen enriched dielectric surface layer, wherein during and/or after said forming the metal diffusion barrier liner, a metal nitride liner forms in a lower region of the metal diffusion barrier liner by reacting metal atoms from said metal diffusion barrier liner with nitrogen atoms from said nitrogen enriched dielectric surface layer;

forming a conductive material on said metal diffusion barrier liner; and

removing said conductive material, said metal diffusion barrier liner and said metal nitride liner that are located outside of the at least one opening to provide a planarized conductive material, a planarized metal diffusion barrier liner and a planarized metal nitride liner, each of which includes an upper surface that is co-planar with an upper surface of the nitrogen enriched dielectric surface layer of the interconnect dielectric material.

2. The method of claim 1, wherein said thermal nitridation does not cause any damage to the exposed surfaces of the interconnect dielectric material.

3. The method of claim 2, wherein said thermal nitridation is performed at a temperature from 50°

C. to 450°

C.

4. The method of claim 3, wherein said non-plasma nitrogen-containing ambient is selected from the group consisting of N₂, NH₃, NH₄, NO, and NH_x wherein x is between 0-1.

5. The method of claim 4, wherein said non-plasma nitrogen-containing ambient has a nitrogen content of from 10% to 100%.

6. The method of claim 1, wherein said metal nitride liner has a graded nitrogen content.

7. The method of claim 1, wherein said nitrogen enriched dielectric surface is removed from an upper horizontal surface of the interconnect dielectric during said removing of said conductive material, said metal diffusion barrier liner and said metal nitride liner.

8. The method of claim 1, wherein said thermal nitridation is performed at an electrical bias of 200 W or less.

9. The method of claim 1, wherein said nitrogen enriched dielectric surface layer extends inward from said exposed surfaces to a depth of 0.5 nm to 20 nm.

10. The method of claim 1, wherein said another metal nitride liner is formed in-situ during the formation of the metal diffusion barrier liner.

11. The method of claim 1, wherein said another metal nitride liner is formed in-situ after the formation of the metal diffusion barrier liner.

12. A method of forming an interconnect structure, said method comprising:

forming at least one opening into an interconnect dielectric material;

forming a nitrogen enriched dielectric surface layer within exposed surfaces of said interconnect dielectric material, wherein said nitrogen enriched dielectric surface layer is formed by thermal nitridation in a non-plasma nitrogen-containing ambient, said nitrogen enriched dielectric surface layer has a higher nitrogen content than a remaining portion of the interconnect dielectric material;

forming a metal nitride liner and a metal diffusion barrier liner on said nitrogen enriched dielectric surface layer, wherein during and/or after said forming of the metal nitride liner, another metal nitride liner forms in a lower region of the metal nitride liner by reacting metal atoms from said metal nitride liner with nitrogen atoms of said nitrogen enriched dielectric surface layer;

forming a conductive material on said metal diffusion barrier liner; and

removing said conductive material, said metal diffusion barrier liner, said metal nitride liner and said another metal nitride liner that are located outside of the at least one opening to provide a planarized conductive material, a planarized metal diffusion barrier liner, a planarized metal nitride layer and another planarized metal nitride liner, each of which includes an upper surface that is co-planar with an upper surface of the nitrogen enriched dielectric surface layer of the interconnect dielectric material.

13. The method of claim 12, wherein said thermal nitridation does not cause any damage to the exposed surfaces of the interconnect dielectric material.

14. The method of claim 13, wherein said thermal nitridation is performed at a temperature from 50°

C. to 450°

C.

15. The method of claim 14, wherein said non-plasma nitrogen-containing ambient is selected from the group consisting of N₂, NH₃, NH₄, NO, and NH_x wherein x is between 0-1.

16. The method of claim 15, wherein said non-plasma nitrogen-containing ambient has a nitrogen content of from 10% to 100%.

17. The method of claim 12, wherein said another metal nitride liner contains a greater nitrogen content than the metal nitride liner.

18. The method of claim 12, wherein said nitrogen enriched dielectric surface is removed from an upper horizontal surface of the interconnect dielectric during said removing of said conductive material, said metal diffusion barrier liner, said metal nitride liner and said another metal nitride liner.

19. The method of claim 12, wherein said thermal nitridation is performed at an electrical bias of 200 W or less.

20. The method of claim 12, wherein said nitrogen enriched dielectric surface layer extends inward from said exposed surfaces to a depth of 0.5 nm to 20 nm.