Methods of forming a metal cap layer on copper-based conductive structures on an integrated circuit device

1. A method, comprising:

forming a trench/opening in a layer of insulating material;

forming a barrier layer in said trench/opening;

forming a first region of a copper material above said barrier layer and in said trench/opening;

forming a metal layer in said trench/opening on said first region of copper material;

forming a second region of copper material on said metal layer;

performing at least one chemical mechanical polishing process to remove any materials positioned above a planarized upper surface of said layer of insulating material outside of said trench/opening so as to thereby define a structure comprised of said metal layer positioned between said first and second regions of copper material;

forming a dielectric cap layer above said layer of insulating material and above said structure; and

after forming said dielectric cap layer, performing a metal diffusion anneal process to cause the metal in said metal layer to diffuse laterally outward and upward, thereby resulting in the formation of a metal cap layer adjacent at least an upper surface of a conductive copper structure.

2. The method of claim 1 , wherein performing said metal diffusion anneal process comprises performing said metal diffusion anneal process at a temperature that falls within the range of 200-400° C. for a duration that falls within the range of about 1-3 hours in an oxygen-free processing ambient.

3. The method of claim 1 , wherein said first region of copper material fills about two-thirds of a depth of said trench/opening.

4. The method of claim of claim 1 , wherein forming said second region of copper material comprises:

performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material; and

performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

5. The method of claim 1 , wherein forming said first region of copper material comprises:

(a) depositing a copper seed layer on said barrier layer;

(b) performing a copper reflow anneal process that causes at least a portion of said copper seed layer to flow to the bottom of said trench/opening; and

(c) repeating steps (a) and (b) until such time as said first region of copper material is formed in said trench/opening.

6. The method of claim 5 , wherein said copper reflow anneal process is performed at a temperature that falls within the range of 100-300° C. for a duration that falls within the range of about 5-60 seconds in an oxygen-free processing ambient.

7. The method of claim 1 , wherein said metal layer is comprised of one of Co, Pt, Ir or W.

8. The method of claim 1 , wherein said metal layer is comprised of a copper-insoluble metal.

9. The method of claim 1 , wherein forming said first region of copper material comprises depositing a copper seed layer on said barrier layer using a bottom-up-fill deposition process so as to form said first region of copper material in the bottom of said trench/opening.

10. The method of claim of claim 9 , wherein forming said second region of copper material comprises:

performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material that is formed on said metal layer; and

performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

11. The method of claim 1 , wherein forming said first region of copper material comprises depositing a first copper seed layer on said barrier layer.

12. The method of claim 11 , wherein forming said second region of copper material comprises:

depositing a second copper seed layer on said metal layer;

performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material that is formed on said second copper seed layer; and

performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

13. The method of claim 1 , wherein said layer of insulating material is comprised of silicon dioxide or an insulating material having a k value less than about 3.3.

14. A method, comprising:

forming a trench/opening in a layer of insulating material having a k value of 3.3 or less;

forming a barrier layer in said trench/opening;

forming a first region of copper material above said barrier layer and in said trench/opening by:

(a) depositing a copper seed layer on said barrier layer;

(b) performing a copper reflow anneal process that causes at least a portion of said copper seed layer to flow to the bottom of said trench/opening; and

(c) repeating steps (a) and (b) until such time as said first region of copper material is formed in said trench/opening;

forming a metal layer in said trench/opening on said first region of copper material;

forming a second region of copper material on said metal layer by performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material that is formed on said metal layer;

performing at least one chemical mechanical polishing process to remove any materials positioned above a planarized upper surface of said layer of insulating material outside of said trench/opening so as to thereby define a structure comprised of said metal layer positioned between said first and second regions of copper material;

forming a dielectric cap layer above said layer of insulating material and above said structure; and

performing a metal diffusion anneal process to cause the metal in said metal layer to diffuse laterally outward and upward, thereby resulting in the formation of a metal cap layer adjacent at least an upper surface of a conductive copper structure.

15. The method of claim 14 , wherein performing said metal diffusion anneal process comprises performing said metal diffusion anneal process at a temperature that falls within the range of 200-400° C. for a duration that falls within the range of about 1-3 hours in an oxygen-free processing ambient.

16. The method of claim 14 , further comprising performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

17. The method of claim 14 , wherein said metal diffusion anneal process is performed after the formation of said dielectric cap layer.

18. A method, comprising:

forming a trench/opening in a layer of insulating material having a k value of 3.3 or less;

forming a barrier layer in said trench/opening;

forming a first region of copper material above said barrier layer and in said trench/opening;

forming a metal layer in said trench/opening on said first region of copper material, wherein forming said first region of copper material comprises depositing a copper seed layer on said barrier layer using a bottom-up-fill deposition process so as to form said first region of copper material in the bottom of said trench/opening;

forming a second region of copper material on said metal layer by performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material that is formed on said metal layer;

performing at least one chemical mechanical polishing process to remove any materials positioned above a planarized upper surface of said layer of insulating material outside of said trench/opening so as to thereby define a structure comprised of said metal layer positioned between said first and second regions of copper material;

forming a dielectric cap layer above said layer of insulating material and above said structure; and

performing a metal diffusion anneal process to cause the metal in said metal layer to diffuse laterally outward and upward, thereby resulting in the formation of a metal cap layer adjacent at least an upper surface of a conductive copper structure.

19. The method of claim 18 , wherein performing said metal diffusion anneal process comprises performing said metal diffusion anneal process at a temperature that falls within the range of 200-400° C. for a duration that falls within the range of about 1-3 hours in an oxygen-free processing ambient.

20. The method of claim 19 , further comprising performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

21. The method of claim 18 , wherein said metal diffusion anneal process is performed after the formation of said dielectric cap layer.

22. A method, comprising:

forming a trench/opening in a layer of insulating material having a k value of 3.3 or less;

forming a barrier layer in said trench/opening;

forming a first region of copper material above said barrier layer and in said trench/opening, wherein forming said first region of copper material comprises depositing a first copper seed layer on said barrier layer;

forming a metal layer in said trench/opening on said first region of copper material;

forming a second region of copper material on said metal layer by depositing a second copper seed layer on said metal layer and performing an electroplating deposition process so as to over-fill said trench/opening with a bulk copper material that is formed on said second copper seed layer;

performing at least one chemical mechanical polishing process to remove any materials positioned above a planarized upper surface of said layer of insulating material outside of said trench/opening so as to thereby define a structure comprised of said metal layer positioned between said first and second regions of copper material;

forming a dielectric cap layer above said layer of insulating material and above said structure; and

performing a metal diffusion anneal process to cause the metal in said metal layer to diffuse laterally outward and upward, thereby resulting in the formation of a metal cap layer adjacent at least an upper surface of a conductive copper structure.

23. The method of claim 22 , wherein performing said metal diffusion anneal process comprises performing said metal diffusion anneal process at a temperature that falls within the range of 200-400° C. for a duration that falls within the range of about 1-3 hours in an oxygen-free processing ambient.

24. The method of claim 23 , further comprising performing a post-plating anneal process at a temperature within the range of 25-400° C. for a duration of about 1-60 seconds in an oxygen-free ambient.

25. The method of claim 22 , wherein said metal diffusion anneal process is performed after the formation of said dielectric cap layer.