METHODS FOR REDUCING METAL OXIDE SURFACES TO MODIFIED METAL SURFACES

• US 20140199497A1
• Filed: 01/14/2013
• Published: 07/17/2014
• Est. Priority Date: 01/14/2013
• Status: Abandoned Application

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Huanfeng Zhu
• Inventors: Spurlin, Tighe A., Mayer, Steven T., Reid, Jonathan D., Kolics, Artur, Zhu, Huanfeng
• Application Number:
  US13/741,151
• Publication Number:
  US 20140199497A1
• Time in Patent Office: Days
• US Class Current: 427/558
• CPC Class Codes: C23C 18/1653 Two or more layers with at least one layer obtained by electroless plating and one layer obtained by electroplating
• CPC Class Codes: C23C 18/1882 Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
• CPC Class Codes: C25D 21/12 Process control or regulation controlling or regulating in general G05
• CPC Class Codes: C25D 5/34 Pretreatment of metallic surfaces to be electroplated
• CPC Class Codes: H01L 21/76861 Post-treatment or after-treatment not introducing additional chemical elements into the layer
• CPC Class Codes: H01L 21/76873 for electroplating

Abstract

Method and apparatus for reducing metal oxide surfaces to modified metal surfaces are disclosed. Metal oxide surfaces are reduced to form a film integrated with a metal seed layer by contacting a solution with a reducing agent with the metal oxide surfaces. The solution with the reducing agent can contact the metal oxide surfaces under conditions that form an integrated film with the metal seed layer, and that reduces reoxidation from exposure the ambient environment. In some embodiments, an additive can be included with the reducing agent to form a surface protecting layer on the metal seed layer. In some embodiments, the metal is copper used in damascene copper structures.

Claims

1. A method of preparing substrate with a al seed layer for platting, the method comprising:

receiving a substrate having the metal seed layer on a plating surface of the substrate, wherein a portion of the metal seed layer has been converted to an oxide of the metal;

contacting at least the oxide of the metal with a solution containing a reducing agent under conditions that reduce the oxide of the metal to the metal in the form of a film integrated with the seed layer;

transferring the substrate to a plating bath containing a plating solution; and

plating metal onto the metal seed layer using the plating solution.

2. The method of claim 1, wherein the metal comprises copper.

3. The method of claim 1, wherein the average thickness of the metal seed layer is less than about 100 Å

.

4. The method of claim 1, wherein the metal seed layer includes a semi-noble metal that serves as a diffusion barrier.

5. The method of claim 1, wherein the reducing agent comprises a boron-containing compound.

6. The method of claim 5, wherein the boron-containing compound is a borane complex selected from the group consisting of:

ammonia borane, dimethyl amine borane (DMAB), diethyl amine borane (DEAB), morpholine borane, and isopropyl amine borane.

7. The method of claim 5, wherein the boron-containing compound is a borohydride.

8. The method of claim 1, wherein the reducing agent comprises a nitrogen-containing compound.

9. The method of claim 8, wherein the nitrogen-containing compound is a hydrazine compound selected from the group consisting of:

hydrazine, hydrazine chloride, hydrazine bromide, and hydrazine hydrate.

10. The method of claim 1, wherein the reducing agent comprises a phosphorus-containing compound.

11. The method of claim 10, wherein the phosphorus-containing compound is a hypophosphite compound selected from the group consisting of:

sodium hypophosphite, calcium hypophosphite, hypophosphorus acid, and hypophosphite monohydrate.

12. The method of claim 1, wherein the contacting step is performed in an inert atmosphere.

13. The method of claim 1, herein the contacting step is performed a reducing gas atmosphere.

14. The method of claim 1, wherein the contacting step is performed at a temperature between about 10°

C. and about 100°

C.

15. The method of claim 1, wherein the solution containing the reducing agent has a between about 7 and about 12.

16. The method of claim 1, wherein the concentration of the solution containing the reducing agent is between about 0.1 M and about 5 M.

17. The method of claim 1, wherein the concentration of dissolved oxygen in the solution containing the reducing agent is between about 0 ppm and about 10 ppm.

18. The method of claim 1, wherein the solution containing the reducing agent further comprises an additive, wherein the additive forms a surface protecting coating on the metal seed layer.

19. The method of claim 18, further comprising removing the surface protecting coating using at least one of an acid, heat, or ultraviolet light treatment.

20. The method of claim 18, wherein the additive comprises accelerators.

21. The method of claim 1, wherein the solution containing the reducing agent further comprises an additive, wherein the additive increases the wetting potential of the surface of the metal seed layer.

22. The method of claim 1, wherein the solution containing the reducing agent further comprises an additive, wherein the additive increases the stability of the reducing agent.

23. The method of claim 1, wherein the solution containing the reducing agent further comprises a metal salt, wherein the metal salt forms a protective sacrificial layer over the metal seed layer.

24. The method of claim 23, further comprising removing the protective sacrificial layer using an acid.

25. The method of claim 1, wherein the contacting step and the plating metal step occur in the same solution, wherein the plating metal step comprises electrolessly plating metal.

26. The method of claim 1, wherein the substrate is maintained under an atmosphere substantially free of oxygen while transferring the substrate to the plating bath.

27. The method of claim 1, further comprising rinsing the substrate prior to transferring the substrate to substantially remove the reducing agent from the surface of the metal seed layer.

28. The method of claim 1, wherein the solution containing the reducing agent is substantially free of metal ions.

36. The method of claim 1, wherein the plating surface of the substrate comprises recesses having height to width aspect ratios of greater than about 5:

1.

29. An apparatus for preparing a substrate with a metal seed layer for plating, the apparatus comprising a controller with instructions for performing the following operations:

(a) receiving a substrate having the metal seed layer on a plating surface of the substrate, wherein a portion of the metal seed layer has been converted to an oxide of the metal;

(b) contacting at least the oxide of the metal with a solution containing a reducing agent under conditions that reduce the oxide of the metal to the metal in the form of a film integrated with the seed layer;

(c) transferring the substrate to a plating bath containing a plating solution; and

(d) plating metal onto the metal seed layer using the plating solution.

30. The apparatus of claim 29, wherein operation (b) comprises immersing the substrate in the solution containing the reducing agent.

31. The apparatus of claim 29, wherein operation (b) comprises spraying the substrate with the solution containing the reducing agent.

32. The apparatus of claim 29, wherein the metal comprises copper.

33. The apparatus of claim 29, wherein operation (c) is performed in an atmosphere substantially free of oxygen.

34. The apparatus of claim 29, wherein the solution containing the reducing agent is substantially free of metal ions.

35. The apparatus of claim 29, wherein the solution containing the reducing agent further comprises at least one of an organic additive or a metal salt.

37. The apparatus of claim 29, wherein the plating surface of the substrate comprises recesses having height to width aspect ratios of greater than about 5:

1.