Method of growing electrical conductors

• US 7,494,927 B2
• Filed: 03/20/2003
• Issued: 02/24/2009
• Est. Priority Date: 05/15/2000
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Soininen, Pekka J., Elers, Kai-Erik, Haukka, Suvi, Kostamo, Juhana
• Primary Examiner(s): Nguyen; Dao H
• Application Number:
  US10/394,430
• Publication Number:
  US 20040005753A1
• Time in Patent Office: 2,168 Days
• Field of Search: 438/628, 438/685, 438/686
• US Class Current: 438/685
• CPC Class Codes: C23C 16/40 Oxides
• CPC Class Codes: C23C 16/406 of iron group metals
• CPC Class Codes: C23C 16/408 of copper or solid solutions thereof
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01L 21/28562 Selective deposition
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76861 Post-treatment or after-treatment not introducing additional chemical elements into the layer
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76874 for electroless plating
• CPC Class Codes: H01L 21/76886 Modifying permanently or temporarily the pattern or the conductivity of conductive members, e.g. formation of alloys, reduction of contact resistances

Abstract

A method for forming a conductive thin film includes depositing a metal oxide thin film on a substrate by an atomic layer deposition (ALD) process. The method further includes at least partially reducing the metal oxide thin film by exposing the metal oxide thin film to a reducing agent, thereby forming a seed layer. In one arrangement, the reducing agent comprises one or more organic compounds that contain at least one functional group selected from the group consisting of —OH, —CHO, and —COOH. In another arrangement, the reducing agent comprises an electric current.

Claims

1. A method of producing a conductive thin film, comprising:

depositing a metal oxide thin film on a substrate by an atomic layer deposition (ALD) process, wherein the metal oxide thin film is selected from the group consisting of ReO₂, Re₂O₅, ReO₃, RuO₂, OsO₂, CoO, Co₃O₄, Rh₂O₃, RhO₂, IrO₂, NiO, PdO, PtO₂, Cu₂O, CuO, AgO, Ag₂O, and Au₂O₃; and

at least partially reducing the metal oxide thin film by exposing the metal oxide thin film to an electric current, thereby forming a seed layer.

2. The method of claim 1, wherein the metal oxide thin film is at least 0.6 nanometers thick.

3. The method of claim 1, wherein the metal oxide thin film has a thickness between approximately 1 nanometer and approximately 20 nanometers.

4. The method of claim 1, wherein the metal oxide thin film has a thickness between approximately 1 nanometer and approximately 3 nanometers.

5. The method of claim 1, wherein depositing comprises at least three cycles of the ALD process.

6. The method of claim 1, wherein the metal oxide thin film has a resistivity less than about 500 μ

Ω

-cm.

7. The method of claim 1, wherein the metal oxide thin film has a resistivity less than about 300 μ

Ω

-cm.

8. The method of claim 1, wherein the metal oxide thin film has a resistivity less than about 100 μ

Ω

-cm.

9. The method of claim 1, wherein the metal oxide thin film comprises RuO₂ and has a resistivity of about 35 μ

Ω

-cm.

10. The method of claim 1, wherein the ALD process comprises feeding into the reaction chamber and contacting the substrate with alternating vapor phase pulses of at least one first source chemical comprising a compound capable of adsorbing no more than a monolayer of metal species on the substrate and at least one second source chemical comprising a compound capable of oxidizing the metal species on the substrate into the metal oxide.

11. The method of claim 10, wherein the first source chemical is Cu(thd)₂ and the second source chemical is selected from the group consisting of ozone (O₃), oxygen (O₂) and a mixture of O₃ and O₂.

12. The method of claim 10, wherein the first source chemical is copper(II)acetylacetonate and the second source chemical is selected from the group consisting of ozone (O₃), oxygen (O₂) and a mixture of O₃ and O₂.

13. The method of claim 10, wherein the first source chemical is anhydrous metal nitrate and the second source chemical is vaporized aqueous solution of NH₃.

14. The method of claim 10, wherein the first source chemical is anhydrous copper nitrate (Cu(NO₃)₂) and the second source chemical is vaporized aqueous solution of NH₃.

15. The method of claim 10, wherein the first source chemical is Co(thd)₃ and the second source chemical is selected from the group consisting of ozone (O₃), oxygen (O₂), and a mixture of O₃ and O₂.

16. The method of claim 10, wherein the first source chemical is Pd(thd)₃ and the second source chemical is selected from the group consisting of ozone (O₃), oxygen (O₂), and a mixture of O₃ and O₂.

17. The method of claim 10, wherein the first source chemical is bis(ethylcyclopentadienyl)ruthenium ((EtCp)₂Ru) and the second source chemical is a mixture of oxygen and water gases.

18. The method of claim 1, wherein the substrate comprises a barrier film and the metal oxide thin film is deposited onto the barrier film.

19. The method of claim 18, wherein the barrier film comprises a material selected from the group consisting of TiN and WNC.

20. The method of claim 1, wherein the electric current is provided by an electrolyte solution comprising a water-soluble metal hydroxide.

21. The method of claim 20, wherein the water-soluble metal hydroxide comprises sodium hydroxide.

22. The method of claim 20, wherein the electric current is applied while bubbling inert gas through the electrolyte solution.

23. The method of claim 1, wherein the electric current is applied while the substrate is at temperatures between about 0°

C. and about 100°

C.

24. The method of claim 1, wherein the electric current is applied while the substrate is at temperatures between about 20°

C. and about 80°

C.

25. The method of claim 1, wherein the electric current is applied while the substrate is at temperatures between about 50°

C. and about 60°

C.

26. The method of claim 1, wherein the electric current is applied for a time period between about 1 second and about 3600 seconds.

27. The method of claim 1, wherein the electric current is applied for a time period between about 30 seconds and about 1000 seconds.

28. The method of claim 1, wherein the metal oxide thin film is exposed to the electric current in an electrochemical deposition (ECD) tool.

29. The method of claim 28, further comprising depositing metal onto the seed layer by an electrochemical deposition (ECD) process in the ECD tool.

30. The method of claim 29, further comprising repairing the seed layer prior to the ECD process.

31. The method of claim 1, further comprising depositing metal onto the seed layer by an electrochemical deposition (ECD) process.

32. The method of claim 31, further comprising repairing the seed layer prior to the ECD process.

33. The method of claim 1, wherein the reduction of the metal oxide thin film essentially converts the metal oxide into an elemental metal seed layer which has sufficient conductivity to be used for subsequent electrochemical deposition.

34. The method of claim 1, wherein the reduction of the metal oxide thin film essentially converts the metal oxide into an elemental metal to provide sufficient conductivity to be used as an electrode of a capacitor.

35. The method of claim 1, wherein the seed layer has a resistivity between about 1 μ

Ω

-cm and about 30 μ

Ω

-cm.

36. The method of claim 1, wherein the seed layer has a resistivity between about 1.67 μ

Ω

-cm and about 10 μ

Ω

-cm.

37. The method of claim 1, wherein the seed layer has a resistivity between about 1.7 μ

Ω

-cm and about 3 μ

Ω

-cm.

38. A method of producing a conductive thin film comprising the steps of:

A. placing a substrate in a chamber;

B. exposing the substrate to a vapor phase first reactant, wherein the first reactant adsorbs no more than a monolayer of metal species on the substrate;

C. removing excess first reactant from the chamber;

D. exposing the substrate to a second vapor phase reactant comprising a compound that is capable of oxidizing the adsorbed metal species on the substrate into metal oxide;

E. removing excess second reactant from the chamber;

F. repeating the above steps B through E at least three times to form a metal oxide film, wherein the metal oxide thin film is selected from the group consisting of ReO₂, Re₂O₅, ReO₃, RuO₂, OsO₂, CoO, Co₃O₄, Rh₂O₃, RhO₂, IrO₂, NiO, PdO, PtO₂, Cu₂O, CuO, AgO, Ag₂O, and Au₂O₃; and

G. following step F, exposing the substrate to an electric current to reduce the metal oxide to metal, thereby forming a seed layer.

39. The method of claim 38, wherein in step F, steps B through E are repeated at least 10 times to form a metal oxide film.

40. A method of producing a conductive thin film comprising:

depositing a metal oxide thin film of at least 0.6 nanometers thickness on a substrate by an atomic layer deposition (ALD) process, wherein the metal oxide thin film is selected from the group consisting of ReO₂, Re₂O₅, ReO₃, RuO₂, OsO₂, CoO, Co₃O₄, Rh₂O₃, RhO₂, IrO₂, NiO, PdO, PtO₂, Cu₂O, CuO, AgO, Ag₂O, and Au₂O₃; and

reducing said metal oxide thin film to a metal film on said substrate by exposing the metal oxide thin film to an electric current, thereby forming a seed layer.

41. A method of producing a conductive thin film, comprising:

depositing a metal oxide thin film on a substrate by an atomic layer deposition (ALD) process, wherein the metal oxide thin film is selected from the group consisting of ReO₂, Re₂O₅, ReO₃, RuO₂, OsO₂, CoO, Co₃O₄, Rh₂O₃, RhO₂, IrO₂, NiO, PdO, PtO₂, Cu₂O, CuO, AgO, Ag₂O, and Au₂O₃; and

at least partially reducing the metal oxide thin film to elemental metal by exposing the metal oxide thin film to an electric current, thereby forming a seed layer.

42. The method of claim 41, wherein at least partially reducing the metal oxide thin film is performed in an electrochemical deposition tool.

43. A method of producing a conductive thin film, comprising:

depositing a metal oxide thin film on a substrate by an atomic layer deposition (ALD) process, wherein the metal oxide thin film is selected from the group consisting of ReO₂, Re₂O₅, ReO₃, RuO₂, OsO₂, CoO, Co₃O₄, Rh₂O₃, RhO₂, IrO₂, NiO, PdO, PtO₂, Cu₂O, CuO, AgO, Ag₂O, and Au₂O₃; and

at least partially reducing the metal oxide thin film to elemental metal in an electrochemical deposition tool, thereby forming a seed layer.

44. The method of claim 43, wherein the metal oxide thin film is at least partially reduced by exposing the metal oxide thin film to an electric current.

45. The method of claim 43, wherein the metal oxide thin film is at least partially reduced by exposing the metal oxide thin film to one or more organic compounds that contain at least one functional group selected from the group consisting of —

OH, —

CHO, and —

COOH.