Method of growing electrical conductors

• US 20050208754A1
• Filed: 08/03/2004
• Published: 09/22/2005
• Est. Priority Date: 08/04/2003
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Kostamo, Juhana, Stokhof, Maarten
• Granted Patent: US 7,067,407 B2
• Time in Patent Office: Days
• US Class Current: 438/622
• CPC Class Codes: C23C 16/40 Oxides
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/28079 the final conductor layer next to the insulator being a single metal, e.g. Ta, W, Mo, Al
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/3141 Deposition using atomic layer deposition techniques [ALD]
• CPC Class Codes: H01L 21/76807 for dual damascene structures
• CPC Class Codes: H01L 21/76823 transforming an insulating layer into a conductive layer
• CPC Class Codes: H01L 21/76826 by contacting the layer with gases, liquids or plasmas
• CPC Class Codes: H01L 21/76828 thermal treatment
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76832 Multiple layers
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• 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 28/65 comprising a noble metal or a noble metal oxide, e.g. platinum (Pt), ruthenium (Ru), ruthenium dioxide (RuO2), iridium (Ir), iridium dioxide (IrO2)

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 gaseous inorganic reducing agent, thereby forming a metal layer. In preferred arrangements, the reducing agent comprises of thermal hydrogen (H₂), hydrogen radicals (H*) and/or carbon monoxide (CO).

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; and

at least partially reducing the metal oxide thin film by exposing the metal oxide thin film to a gaseous inorganic reducing agent, thereby forming a metal 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 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.

7. 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 molecular 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.

8. The method of claim 7, 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.

9. The method of claim 7, wherein the first source chemical is copper(II)acetylacetonate Cu(acac)₂ and the second source chemical is selected from the group consisting of ozone (O₃), oxygen (O₂) and a mixture of O₃ and O₂.

10. The method of claim 7, 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.

11. The method of claim 7, wherein the first source chemical is Pd(thd)₃ and the second source chemical is selected from the group consisting of ozone (03), oxygen (O₂), and a mixture of O₃ and O₂.

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

13. The method of claim 12, wherein the barrier film comprises a material selected from the group consisting of TiN, Ta, TaN and WNC.

14. The method of claim 1, wherein the inorganic reducing agent is selected from the group consisting of thermal hydrogen (H₂), hydrogen radicals (H*) and carbon monoxide (CO).

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

16. The method of claim 15, further comprising repairing the metal layer prior to the ECD process.

17. The method of claim 1, further comprising depositing metal onto the metal layer by a metal organic chemical vapor deposition (MOCVD) process in a CVD tool.

18. The method of claim 1, further comprising depositing metal onto the metal layer by a copper superfill process in the CVD tool.

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

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

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

Ω

-cm and about 30 μ

Ω

-cm.

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

Ω

-cm and about 10 μ

l-cm.

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

Ω

-cm and about 3 μ

Ω

-cm.

24. 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 molecular monolayer of metal species on the substrate;

C. removing excess first reactant and gaseous reaction byproducts 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 and gaseous reaction byproducts from the chamber;

F. repeating the above steps B through E at least three times to form a metal oxide film; and

G. following step F, exposing the substrate to a gaseous inorganic reducing agent to reduce the metal oxide film to metal.

25. The method of claim 24, wherein in step F, is repeated at least 10 times to form the metal oxide film prior to step G.

26. A method of producing an electrically conductive thin film, comprising:

depositing a metal oxide thin film on a partially fabricated integrated circuit by an atomic layer deposition (ALD) process, the metal oxide thin film having a thickness of at least 0.6 nm; and

at least partially reducing the metal oxide thin film to elemental metal with a gaseous inorganic reducing agent.

27. The method of claim 26, wherein depositing the metal oxide thin film comprises an atomic layer deposition process.

28. The method of claim 27, wherein at least partially reducing the metal oxide thin film comprises exposing the metal oxide thin film to one or more gaseous inorganic compounds selected from the group consisting of thermal hydrogen (H₂), hydrogen radicals (H*) and carbon monoxide (CO).

29. The method of claim 28, wherein the reduction temperature is between about 80°

C. and about 350°

C.

30. The method of claim 29, wherein the reduction temperature is between about 150°

C. and about 300°

C.

31. The method of claim 30, wherein the reduction temperature is between about 200°

C. and about 300°

C.

32. The method of claim 26, wherein the metal layer is used as a seed layer for a subsequent metal deposition.

33. The method of claim 28 wherein partially reducing the metal oxide thin film comprises exposing the metal oxide thin film to hydrogen radicals.

34. The method of claim 33, wherein the hydrogen radicals are generated in an atmosphere comprising between about 3 and about 10% flowing hydrogen.

35. The method of claim 34, wherein the hydrogen radicals are generated in an atmosphere comprising about 3.85% flowing hydrogen.

36. The method of claim 33, wherein the hydrogen radicals are generated at a plasma power setting of about 200 to about 2000 W.

37. The method of claim 36, wherein the hydrogen radicals are generated at a plasma power setting of about 1500 W.

38. The method of claim 33, wherein the hydrogen radicals are generated by applying a power of 1500 W to an atmosphere comprising about 3.85% flowing hydrogen.