Process for electroless copper deposition

• US 7,651,934 B2
• Filed: 03/20/2006
• Issued: 01/26/2010
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kovarsky, Nicolay Y., Weidman, Timothy W., Lubomirsky, Dmitry, Shanmugasundram, Arulkumar, Wijekoon, Kapila
• Primary Examiner(s): Lindsay, Jr.; Walter L
• Application Number:
  US11/385,037
• Publication Number:
  US 20070004201A1
• Time in Patent Office: 1,408 Days
• Field of Search: 438/584, 438/585, 438/650, 438/686, 257/E21.577, 257/E21.171, 257/E21.241, 257/E21.576, 257/E21.582, 257/E21.591
• US Class Current: 438/584
• CPC Class Codes: C23C 18/1608 from pretreatment step, i.e. selective pre-treatment
• CPC Class Codes: C23C 18/165 Multilayered product layered product B32B
• CPC Class Codes: C23C 18/1831 Use of metal, e.g. activation, sensitisation with noble metals
• CPC Class Codes: C23C 18/38 Coating with copper
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/76844 Bottomless liners
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76874 for electroless plating

Abstract

Embodiments of the invention provide methods for forming conductive materials within contact features on a substrate by depositing a seed layer within a feature and subsequently filling the feature with a copper-containing material during an electroless deposition process. In one example, a copper electroless deposition solution contains levelers to form convexed or concaved copper surfaces. In another example, a seed layer is selectively deposited on the bottom surface of the aperture while leaving the sidewalls substantially free of the seed material during a collimated PVD process. In another example, the seed layer is conformably deposited by a PVD process and subsequently, a portion of the seed layer and the underlayer are plasma etched to expose an underlying contact surface. In another example, a ruthenium seed layer is formed on an exposed contact surface by an ALD process utilizing the chemical precursor ruthenium tetroxide.

Claims

1. A method for forming a conductive material within a feature on a substrate comprising:

depositing a seed layer selectively onto a bottom surface of a feature on a substrate while sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process; and

depositing a copper-containing layer on the seed layer to fill the feature during an electroless deposition process, wherein the seed layer comprises a metal selected from the group consisting of copper, ruthenium, cobalt, tantalum, titanium, tungsten, rhenium, palladium, platinum, nickel, alloys thereof, and combinations thereof and wherein the seed layer is deposited on a barrier layer disposed on the substrate, the barrier layer comprises a material selected from the group consisting of tantalum, tantalum nitride, tantalum silicon nitride, titanium, titanium nitride, titanium silicon nitride, ruthenium, tungsten, tungsten nitride, alloys thereof, derivatives thereof, and combinations thereof.

2. The method of claim 1, wherein the bottom surface of the feature is exposed to a plasma to remove a portion of the seed layer and the barrier layer and to expose a conductive underlayer prior to filling the feature by the electroless deposition process.

3. A method for forming a conductive material within a feature on a substrate, comprising:

depositing a seed layer selectively onto a bottom surface of a feature on a substrate while sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process; and

depositing a copper-containing layer on the seed layer to fill the feature during an electroless deposition process, wherein the electroless deposition process comprises exposing the substrate to an electroless solution comprising a copper source and at least one additive selected from the group consisting of an accelerator, a suppressor, a leveler, and combinations thereof, wherein the accelerator is a sulfur-based compound selected from the group consisting of bis(3-sulfopropyl) disulfide, 3-mercapto-1-propane sulfonic acid, derivatives thereof, and combinations thereof.

4. A method for forming a conductive material within a feature on a substrate, comprising:

depositing a seed layer selectively onto a bottom surface of a feature on a substrate while sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process; and

depositing a copper-containing layer on the seed layer to fill the feature during an electroless deposition process, wherein the electroless deposition process comprises exposing the substrate to an electroless solution comprising a copper source and at least one additive selected from the group consisting of an accelerator, a suppressor, a leveler, and combinations thereof, wherein the suppressor is polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene copolymer, or derivatives thereof.

5. A method for forming a conductive material within a feature on a substrate, comprising:

depositing a seed layer selectively onto a bottom surface of a feature on a substrate while sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process; and

depositing a copper-containing layer on the seed layer to fill the feature during an electroless deposition process, wherein the electroless deposition process comprises exposing the substrate to an electroless solution comprising a copper source and at least one additive selected from the group consisting of an accelerator, a suppressor, a leveler, and combinations thereof, wherein a surface of the copper-containing layer adjoins the sidewall of the feature at an angle of less than 90°

from the sidewall.

6. The method of claim 5, wherein the angle is within a range from about 5°

to about 45°

.

7. The method of claim 5, wherein a concentration of the leveler is adjusted to control the angle.

8. The method of claim 7, wherein the leveler is an alkylpolyimine compound or an organic sulfonate compound.

9. The method of claim 8, wherein the leveler is selected from the group consisting of 1-(2-hydroxyethyl)-2-imidazolidinethione, 4-mercaptopyridine, 2-mercaptothiazoline, ethylene thiourea, thiourea, derivatives thereof, and combinations thereof.

10. The method of claim 7, wherein the concentration of the leveler is within a range from about 20 ppb to about 600 ppm.

11. The method of claim 10, wherein the leveler is 1-(2-hydroxyethyl)-2-imidazolidinethione.

12. A method for forming a conductive material within a feature on a substrate, comprising:

depositing a seed layer onto a barrier layer disposed on a substrate during a physical vapor deposition process, wherein the substrate contains a feature having sidewalls and a bottom surface;

etching the bottom surface of the feature with a plasma to remove a portion of the seed layer and the barrier layer and to expose a conductive underlayer; and

depositing a copper-containing layer on the conductive underlayer while filling the feature during an electroless deposition process.

13. The method of claim 12, wherein the seed layer comprises a metal selected from the group consisting of copper, ruthenium, cobalt, tantalum, titanium, tungsten, rhenium, palladium, platinum, nickel, alloys thereof, and combinations thereof.

14. The method of claim 13, wherein the seed layer is selectively deposited on the bottom surface of the feature while the sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process.

15. The method of claim 13, wherein the barrier layer comprises a material selected from the group consisting of tantalum, tantalum nitride, tantalum silicon nitride, titanium, titanium nitride, titanium silicon nitride, ruthenium, tungsten, tungsten nitride, alloys thereof, derivatives thereof, and combinations thereof.

16. The method of claim 13, wherein the conductive underlayer contains a metal selected from the group consisting of copper, tungsten, aluminum, alloys thereof, and combinations thereof.

17. The method of claim 16, wherein the plasma is formed by a remote plasma source.

18. The method of claim 12, wherein the electroless deposition process comprises exposing the substrate to an electroless solution comprising a copper source and at least one additive selected from the group consisting of an accelerator, a suppressor, a leveler, and combinations thereof.

19. The method of claim 18, wherein the accelerator is a sulfur-based compound selected from the group consisting of bis(3-sulfopropyl) disulfide, 3-mercapto-1-propane sulfonic acid, derivatives thereof, and combinations thereof.

20. The method of claim 18, wherein the suppressor is polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene copolymer, or derivatives thereof.

21. The method of claim 18, wherein a surface of the copper-containing layer adjoins the sidewall of the feature at an angle of less than 90°

from the sidewall.

22. The method of claim 21, wherein the angle is within a range from about 5°

to about 45°

.

23. The method of claim 21, wherein a concentration of the leveler is adjusted to control the angle.

24. The method of claim 23, wherein the leveler is an alkylpolyimine compound or an organic sulfonate compound.

25. The method of claim 24, wherein the leveler is selected from the group consisting of 1-(2-hydroxyethyl)-2-imidazolid inethione, 4-mercaptopyridine, 2-mercaptothiazoline, ethylene thiourea, thiourea, derivatives thereof, and combinations thereof.

26. The method of claim 23, wherein the concentration of the leveler is within a range from about 20 ppb to about 600 ppm.

27. The method of claim 26, wherein the leveler is 1-(2-hydroxyethyl)-2-imidazolidinethione.

28. A method for forming a conductive material within a feature on a substrate, comprising:

depositing a seed layer onto a barrier layer disposed on a substrate during a physical vapor deposition process, wherein the substrate contains a feature having sidewalls and a bottom surface; and

exposing the substrate to an electroless deposition solution to deposit a copper-containing layer over the seed layer, wherein the electroless deposition solution comprises a leveler at a concentration to form a surface of the copper-containing layer adjoining the sidewall of the feature at an angle of less than 90°

from the sidewall.

29. The method of claim 28, wherein the angle is within a range from about 5°

to about 45°

.

30. The method of claim 28, wherein the concentration of the leveler is adjusted to control the angle.

31. The method of claim 30, wherein the leveler is an alkylpolyimine compound or an organic sulfonate compound.

32. The method of claim 31, wherein the leveler is selected from the group consisting of 1-(2-hyd roxyethyl)-2-imidazolid inethione, 4 -mercaptopyridine, 2 -mercaptothiazoline, ethylene thiourea, thiourea, derivatives thereof, and combinations thereof.

33. The method of claim 30, wherein the concentration of the leveler is within a range from about 20 ppb to about 600 ppm.

34. The method of claim 33, wherein the leveler is 1-(2-hydroxyethyl)-2-imidazolidinethione.

35. The method of claim 29, wherein the electroless solution further comprises a copper source and at least one additive selected from the group consisting of an accelerator, a suppressor, and combinations thereof.

36. The method of claim 35, wherein the accelerator is a sulfur-based compound selected from the group consisting of bis(3-sulfopropyl) disulfide, 3-mercapto-1- propane sulfonic acid, derivatives thereof, and combinations thereof.

37. The method of claim 35, wherein the suppressor is polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene copolymer or derivatives thereof.

38. The method of claim 29, wherein the seed layer comprises a metal selected from the group consisting of copper, ruthenium, cobalt, tantalum, titanium, tungsten, rhenium, palladium, platinum, nickel, alloys thereof, and combinations thereof.

39. The method of claim 38, wherein the seed layer is selectively deposited on the bottom surface of the feature while the sidewalls of the feature remain substantially free of the seed layer during a collimated physical vapor deposition process.

40. The method of claim 38, wherein the barrier layer comprises a material selected from the group consisting of tantalum, tantalum nitride, tantalum silicon nitride, titanium, titanium nitride, titanium silicon nitride, ruthenium, tungsten, tungsten nitride, alloys thereof, derivatives thereof, and combinations thereof.

41. The method of claim 40, wherein the bottom surface of the feature is exposed to a plasma to remove a portion of the seed layer and the barrier layer and to expose a conductive underlayer prior to filling the feature by the electroless deposition process.