Interconnect structure with capping layer and barrier layer

1. A method, comprising:

forming a copper based interconnect structure in an opening of a dielectric material;

forming a capping layer on the copper based interconnect structure, wherein an interface of a bottom surface of the capping layer and a top surface of the copper based interconnect structure is co-planar with a top surface of the dielectric material;

oxidizing the capping layer and any residual material formed on a surface of the dielectric material;

forming a barrier layer on the capping layer by outdiffusing a material from the copper based interconnect structure to a surface of the capping layer; and

removing the residual material, while the barrier layer on the surface of the capping layer protects the capping layer.

2. The method of claim 1 , wherein:

forming the copper based interconnect structure comprises:

forming a layer of Tantalum Nitride (TaN) in the opening;

forming a layer of CuMn on the TaN layer; and

electroplating a copper layer on the CuMn layer; and

forming of the barrier layer comprises outdiffusing Mn to the surface of the capping layer during an anneal process.

3. The method of claim 1 , wherein:

forming the copper based interconnect structure comprises:

forming a layer of Ru, Ag, Zn, Sn or Ni in the opening;

forming a layer of CuMn on the Ru, Ag, Zn, Sn or Ni layer; and

electroplating a copper layer on the CuMn layer; and

forming of the barrier layer comprises outdiffusing Mn to the surface of the capping layer during an anneal process.

4. The method of claim 3 , wherein:

the capping layer is formed by a deposition of Ru, Ag, Zn, Sn or Ni, respectively, on the copper based interconnect structure;

the residual material is oxidized Ru, Ag, Zn, Sn or Ni on the surface of the dielectric material; and

the removing of the residual material comprises a selective etch the oxidized Ru, Ag, Zn, Sn or Ni on the surface of the dielectric material.

5. The method of claim 1 , wherein:

forming the copper based interconnect structure comprises:

forming a layer of cobalt in the opening;

forming a layer of CuMn on the cobalt layer;

electroplating a copper layer on the CuMn layer; and

forming of the barrier layer comprises outdiffusing Mn to the surface of the capping layer during an anneal process.

6. The method of claim 5 , wherein the barrier layer is formed at an interface of the dielectric material and the cobalt in the opening during the anneal process.

7. The method of claim 6 , wherein the capping layer is cobalt and the residual material is oxidized cobalt.

8. The method of claim 6 , wherein the capping layer is Ru, Ag, Zn, Sn or Ni, respectively, resulting in the residual material of Ru, Ag, Zn, Sn or Ni on the surface of the dielectric layer.

9. The method of claim 1 , wherein the forming the copper based interconnect structure comprises:

forming an underlying barrier layer on surfaces of the dielectric material in the opening;

forming a CuMn layer on the underlying barrier layer, wherein a percent Mn of the CuMn layer is in a range of between 0.5 and 20 atomic percent; and

electroplating a copper layer on the CuMn layer.

10. The method of claim 9 , wherein the forming the barrier layer comprises outdiffusing Mn through both the copper layer and the capping layer.

11. The method of claim 9 , further comprising performing a chemical mechanical polish on the top surface of the copper based interconnect structure and the top surface of the dielectric material prior to forming the capping layer on the copper based interconnect structure.

12. The method of claim 1 , wherein the capping layer extends entirely across the top surface of the copper based interconnect structure.

13. A method, comprising:

forming an electroplated copper interconnect structure in a opening of a dielectric material;

selectively forming a capping layer on the electroplated copper interconnect structure which results in residual material forming on a surface of the dielectric material, wherein the capping layer extends entirely across a topmost surface of the electroplated copper interconnect structure;

oxidizing the capping layer and the residual material by exposing the capping layer and residual material to air;

forming a barrier layer on the capping layer by outdiffusing Mn to a surface of the capping layer; and

removing the oxidized residual material with a selective etching process.

14. The method of claim 13 , wherein the barrier layer forms at an interface of the dielectric material and the electroplated copper interconnect structure.

15. The method of claim 14 , wherein the barrier layer on the capping layer protects the capping layer during the selective etching process.

16. The method of claim 14 , wherein the electroplated copper interconnect structure comprises a deposition of cobalt and CuMn and an electroplating of copper, and the capping layer and residual material is cobalt.

17. The method of claim 14 , wherein the electroplated copper interconnect structure comprises a deposition of Ru, Ag, Zn, Sn or Ni and CuMn and an electroplating of copper, and the capping layer and residual material is Ru, Ag, Zn, Sn or Ni.

18. The method of claim 13 , wherein the electroplated copper interconnect structure comprises a deposition of titanium nitride and CuMn and an electroplating of copper and the capping layer and residual material is cobalt.

19. The method of claim 13 , wherein the electroplated copper interconnect structure comprises a deposition of cobalt and CuMn and an electroplating of copper and the capping layer and residual material is Ru, Ag, Zn, Sn or Ni.

20. The method of claim 13 , wherein an interface between a bottom surface of the capping layer and the topmost surface of the electroplated copper interconnect structure is co-planar with a top surface of the dielectric material.