Wetting pretreatment for enhanced damascene metal filling

Patent metadata

Field	Value
Publication number	US-8962085-B2
Application number	US-68478710-A
Country	US
Kind code	B2
Filing date	Jan 8, 2010
Priority date	Jun 17, 2009
Publication date	Feb 24, 2015
Grant date	Feb 24, 2015

Abstract

Disclosed are pre-wetting apparatus designs and methods. These apparatus designs and methods are used to pre-wet a wafer prior to plating a metal on the surface of the wafer. Disclosed compositions of the pre-wetting fluid prevent corrosion of a seed layer on the wafer and also improve the filling rates of features on the wafer.

First claim

What is claimed is:

1. A method of pre-wetting a wafer substrate prior to electrolytically processing the wafer substrate, the method comprising:
(a) providing a wafer substrate having an exposed metal layer on at least a portion of its surface to a pre-wetting process chamber;
(b) reducing pressure in the pre-wetting process chamber to a subatmospheric pressure;
(c) degassing a pre-wetting liquid to remove at least both O 2 and N 2 and introducing the degassed pre-wetting liquid to the pre-wetting process chamber, the pre-wetting process chamber being under the subatmospheric pressure during introduction of the degassed pre-wetting liquid, while preventing gases from the pre-wetting process chamber from being dissolved in the degassed pre-wetting liquid; and
(d) contacting the wafer substrate with the introduced degassed pre-wetting liquid at the subatmospheric pressure to form a wetting layer on the wafer substrate, and to thereby provide a pre-wetted wafer substrate.

2. The method of claim 1 , wherein the wafer substrate is positioned in a substantially horizontal orientation during the contacting.

3. The method of claim 2 , wherein (d) comprises contacting the wafer substrate with the introduced degassed pre-wetting liquid from about 10 seconds to 120 seconds.

4. The method of claim 1 , wherein the wafer substrate is positioned in a substantially vertical orientation during the contacting.

5. The method of claim 1 , wherein the wafer substrate has at least one recessed feature.

6. The method of claim 5 , wherein the recessed feature is a damascene feature.

7. The method of claim 5 , wherein the recessed feature is a through-mask feature.

8. The method of claim 1 , wherein contacting the wafer substrate with the introduced degassed pre-wetting liquid comprises immersing the wafer substrate in the introduced degassed pre-wetting liquid.

9. The method of claim 1 , wherein contacting the wafer substrate with the introduced degassed pre-wetting liquid comprises spraying or covering the wafer substrate with the introduced degassed pre-wetting liquid.

10. The method of claim 1 , wherein (d) comprises:
rotating the wafer substrate while the introduced degassed pre-wetting liquid contacts the wafer substrate.

11. The method of claim 10 , wherein the wafer substrate is rotated at a rate of between about 10 rpm to 300 rpm.

12. The method of claim 11 , wherein the wafer substrate is rotated at a rate of between about 10 rpm to 100 rpm.

13. The method of claim 1 , further comprising:
removing excess of the introduced degassed pre-wetting liquid from the wafer substrate.

14. The method of claim 13 , wherein the excess of the introduced degassed pre-wetting liquid is removed from the wafer substrate by rotating the wafer substrate.

15. The method of claim 14 , wherein the wafer substrate is rotated from about 300 rpm to 1000 rpm during removal of the excess of the introduced degassed pre-wetting liquid.

16. The method of claim 14 , wherein the wafer substrate is rotated less than about 20 seconds during removal of the excess of the introduced degassed pre-wetting liquid.

17. The method of claim 1 , further comprising:
after contacting the wafer substrate with the introduced degassed pre-wetting liquid, raising the pressure in the pre-wetting process chamber to an atmospheric pressure.

18. The method of claim 17 , wherein raising the pressure in the pre-wetting process chamber to an atmospheric pressure comprises filling the pre-wetting process chamber with an oxygen-free gas.

19. The method of claim 1 further comprising:
removing the pre-wetted wafer substrate from the pre-wetting process chamber; and
transferring the pre-wetted wafer substrate to a chamber configured to perform an anodic process selected from the group consisting of electroetching and electropolishing.

20. The method of claim 1 further comprising:
removing the pre-wetted wafer substrate from the pre-wetting process chamber; and
transferring the pre-wetted wafer substrate to an electroplating chamber.

21. The method of claim 20 , wherein the pre-wetted wafer substrate is exposed to an environment outside of the pre-wetting process chamber and the electroplating chamber for less than about one minute.

22. The method of claim 20 , further comprising electroplating a layer of metal on the pre-wetted wafer substrate.

23. The method of claim 22 , wherein the electroplated metal is copper.

24. The method of claim 20 , further comprising cathodically polarizing the pre-wetted wafer substrate with respect to a plating solution in the electroplating chamber before contacting the pre-wetted wafer substrate with the plating solution.

25. The method of claim 20 , further comprising electroplating the wafer substrate in the electroplating chamber using a degassed plating solution.

26. The method of claim 20 , wherein the pre-wetting process chamber and the electroplating chamber are distinct stations of one apparatus module.

27. The method of claim 1 , further comprising electroplating a layer of metal on the pre-wetted wafer substrate in the pre-wetting process chamber.

28. The method of claim 27 , wherein the electroplating is performed using a degassed plating solution.

29. The method of claim 1 , further comprising:
cooling the pre-wetting liquid to less than about 20° C. during the degassing of the pre-wetting liquid.

30. The method of claim 1 further comprising:
transferring the pre-wetted wafer substrate to an electroplating chamber, wherein the wetting layer on the pre-wetted wafer substrate has a thickness of between about 50 to 500 μm immediately prior to electroplating.

31. The method of claim 1 , wherein the pre-wetting liquid is water.

32. The method of claim 1 , further comprising electroplating a layer of metal on the pre-wetted wafer substrate in the pre-wetting process chamber, wherein the pre-wetting liquid and a plating solution have the same composition.

33. The method of claim 1 , wherein the pre-wetting liquid comprises a water-miscible solvent selected from the group consisting of an alcohol, a dialkylcarbonate, dimethylformamide, and dimethyl sulfoxide.

34. The method of claim 1 , wherein the pre-wetting liquid comprises water and a copper salt.

35. The method of claim 34 , wherein the pre-wetting liquid comprises a copper salt at a concentration of at least about 50% of a saturation limit.

36. The method of claim 34 , wherein the copper salt is selected from the group consisting of copper sulfate, a copper alkylsulphonate, and mixtures thereof.

37. The method of claim 34 , further comprising electroplating a layer of copper on the pre-wetted wafer substrate with a copper-containing plating solution, wherein the pre-wetting liquid contains a copper salt at a copper concentration that is the same or higher than the copper concentration in the plating solution.

38. The method of claim 37 , wherein the copper concentration in the pre-wetting liquid is at least about 25% greater than the copper concentration in the plating solution.

39. The method of claim 34 , wherein the copper salt is at a concentration of greater than about 20 g/L of copper.

Assignees

• Mayer Steven T
• Porter David W
• Willey Mark J
• Novellus Systems Inc

Inventors

• Mayer Steven T
• Porter David W
• Willey Mark J

Classifications

• H10W20/023

  the interconnections being through-semiconductor vias · CPC title

• H10W20/052

  by treatments not introducing additional elements therein · CPC title

• H10P14/47 Primary

  Electrolytic deposition, i.e. electroplating; Electroless plating · CPC title

• C25D17/001

  Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells · CPC title

• C25D7/123 Primary

  Semiconductors first coated with a seed layer or a conductive layer · CPC title