Metal anneal with oxidation prevention

• US 6,679,951 B2
• Filed: 11/13/2001
• Issued: 01/20/2004
• Est. Priority Date: 05/15/2000
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Elers, Kai-Erik, Soininen, Pekka J., Granneman, Ernst H. A.
• Primary Examiner(s): Oltmans, Andrew L.
• Application Number:
  US09/991,332
• Publication Number:
  US 20020092584A1
• Time in Patent Office: 798 Days
• Field of Search: 148/240, 148/274, 148/276, 148/280, 148/282, 148/687, 427/255.14, 427/255.21
• US Class Current: 148/240
• CPC Class Codes: H01L 21/321 After treatment
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material

Abstract

The invention relates generally to the prevention of copper oxidation during copper anneal processes. In one aspect of the invention, copper oxidation is prevented by carrying out the anneal in the presence of one or more organic reducing agents.

Claims

1. A process for annealing a metal layer on a semiconductor substrate in a reaction chamber comprising:

heating the substrate to a temperature suitable for annealing the metal; and

contacting the substrate with one or more organic reducing agents during at least part of the time the substrate is sufficiently heated to cause oxidation of the metal layer.

2. The process of claim 1, wherein the substrate is contacted with one or more organic reducing agents during loading and unloading of the substrate from the reaction chamber.

3. The process of claim 1, wherein the substrate is contacted with one or more organic reducing agents during loading and unloading.

4. The process of claim 1, wherein the organic reducing agent comprises at least one functional group selected from the group consisting of alcohol (—

OH), aldehyde (—

CHO), and carboxylic acid (—

COOH).

5. The process of claim 4, wherein the organic reducing agent is selected from the group consisting of primary alcohols, secondary alcohols, tertiary alcohols, polyhyrdroxyalcohols, cyclic alcohols, and halogenated alcohols.

6. The process of claim 4 wherein said organic reducing agent is selected from the group consisting of:

compounds having the general formula R³—

CHO, wherein R³ is hydrogen or a linear or branched C₁—

C₂₀ alkyl or alkenyl group;

compounds having the general formula OHC—

R⁴—

CHO, wherein R⁴ is a linear or branched C₁—

C₂₀ saturated or unsaturated hydrocarbon;

a compound of the formula OHC—

CHO;

halogenated aldehydes; and

other derivatives of aldehydes.

7. The process of claim 4 wherein the organic reducing agent is selected from the group consisting of:

compounds of the general formula R⁵COOH, wherein R⁵ is hydrogen or a linear or branched C₁-C₂₀ alkyl or alkenyl group;

polycarboxylic acids;

halogenated carboxylic acids; and

other derivatives of carboxylic acids.

8. The process of claim 1, wherein the organic reducing agent is in the vapor phase.

9. The process of claim 1, wherein the temperature suitable for annealing the metal is less than about 500°

C.

10. The process of claim 1, wherein the substrate is heated in a reactor comprising an upper part and a lower part.

11. The process of claim 10, wherein the substrate is held in a floating state between the upper part and lower part during annealing.

12. The process of claim 10, wherein the temperature of the upper part and lower part are constant.

14. The process of claim 1, wherein the substrate is heated by loading into a reaction space at the temperature suitable for annealing.

15. The process of claim 1, wherein said metal layer is a copper layer.

13. A process for annealing a metal layer on a semiconductor substrate in a reaction chamber, comprising:

heating the substrate to a temperature suitable for annealing the metal; and

contacting the substrate with one or more organic reducing agents during at least part of the time the substrate is sufficiently heated to cause oxidation of the metal layer,

wherein the substrate is heated in a reactor comprising an upper part and a lower part, wherein the temperature of the upper part and lower part are constant and wherein the temperature of the upper part is about 250°

C.

16. A process for producing an integrated circuit comprising depositing a layer of copper on a semiconductor substrate and annealing the copper layer in the presence of one or more organic reducing agents, whereby oxidation of the copper layer is prevented during the anneal.

17. The process of claim 16, wherein the organic reducing agent comprises at least one functional group selected from the group consisting of alcohol (—

OH), aldehyde (—

CHO), and carboxylic acid (—

COOH).

18. The process of claim 17, wherein the organic reducing agent is selected from the group consisting of primary alcohols, secondary alcohols, tertiary alcohols, polyhyrdroxyalcohols, cyclic alcohols, and halogenated alcohols.

19. The process of claim 17, wherein said organic reducing agent is selected from the group consisting of:

compounds having the general formula R³—

CHO, wherein R³ is hydrogen or a linear or branched C₁-C₂₀ alkyl or alkenyl group;

compounds having the general formula OHC—

R⁴—

CHO, wherein R⁴ is a linear or branched C₁-C₂₀ saturated or unsaturated hydrocarbon;

a compound of the formula OHC—

CHO;

halogenated aldehydes; and

other derivatives of aldehydes.

20. The process of claim 17, wherein the organic reducing agent is selected from the group consisting of:

compounds of the general formula R⁵COOH, wherein R⁵ is hydrogen or a linear or branched C₁-C₂₀ alkyl or alkenyl group;

polycarboxylic acids;

halogenated carboxylic acids; and

other derivatives of carboxylic acids.

21. The process of claim 16, wherein the copper is annealed at a temperature between about 150°

C. and about 450°

C.

22. A process for producing an integrated circuit comprising depositing a layer of copper on a substrate and annealing the copper layer in the presence of one or more organic reducing agents, whereby oxidation of the copper layer is prevented during the anneal, wherein the copper is annealed at a temperature between about 250°

C. and about 350°

C.

23. A process for annealing a copper layer during the production of an integrated circuit comprising:

loading a semiconductor substrate comprising a copper layer into a reaction chamber; and

contacting the copper layer with one or more organic reducing agents while heating the substrate to an annealing temperature between about 150°

C. and about 450°

C.

25. The process of claim 23 wherein the organic reducing agents are in the vapor phase.

27. The process of claim 23, wherein the substrate is loaded while the reaction chamber is at the annealing temperature.

28. The process of claim 23, wherein the substrate is maintained at the annealing temperature for between about 5 and 120 seconds.

29. The process of claim 28, wherein the substrate is maintained at the annealing temperature for between about 30 and 60 seconds.

30. The process of claim 23, wherein the partial pressure of the organic reducing agent in the reaction chamber is between about 0.01 and 20 mbar during the annealing process.

31. The process of claim 30, wherein the partial pressure of the organic reducing agent in the reaction chamber is between about 1 and 10 mbar during the annealing process.

32. The process of claim 23, wherein the reaction chamber is clustered with a copper deposition tool.

24. A process for annealing a copper layer during the production of an integrated circuit comprising:

loading a substrate comprising a copper layer into a reaction chamber; and

contacting the copper layer with one or more organic reducing agents while heating the substrate to an annealing temperature between about 250°

C. and about 350°

C.

26. A process for annealing a copper layer during the production of an integrated circuit comprising:

loading a substrate comprising a copper layer into a reaction chamber; and

contacting the copper layer with one or more organic reducing agents while heating the substrate to an annealing temperature between about 150°

C. and about 450°

C,

wherein the substrate is maintained at a temperature of less than about 65°

C. during loading and unloading.

33. A process for annealing a metal layer on a semiconductor substrate comprising annealing the metal layer on the substrate in a reaction chamber and contacting the substrate with one or more flowing organic reducing agents while the substrate is present in the reaction chamber in which the metal layer is annealed.

34. The process of claim 33, wherein the substrate is contacted with one or more organic reducing agents during loading and unloading of the substrate from the reaction chamber which the metal layer is annealed.

35. The process of claim 33, wherein the substrate is contacted with one or more organic reducing agents between the loading and unloading of the substrate from the reaction chamber in which the metal is annealed.

36. The process of claim 33, wherein the flow of organic reducing agent is shut off after a sufficient amount of time to purge the reaction chamber.