Processes and systems for engineering a barrier surface for copper deposition

• US 20070292603A1
• Filed: 08/30/2006
• Published: 12/20/2007
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Dordi, Yezdi, Boyd, John, Arunagiri, Tiruchirapalli, Yoon, Hyungsuk Alexander, Redeker, Fritz C., Thie, William, Howald, Arthur M.
• Granted Patent: US 8,241,701 B2
• Time in Patent Office: Days
• US Class Current: 427/98.1
• CPC Class Codes: C23C 18/1632 Features specific for the apparatus, e.g. layout of cells and of its equipment, multiple cells
• CPC Class Codes: C23C 18/1651 Two or more layers only obtained by electroless plating
• CPC Class Codes: C23C 18/1844 with use of organic or inorganic compounds other than metals, first
• CPC Class Codes: H01L 21/0206 during, before or after processing of insulating layers
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 21/02074 the processing being a planarization of conductive layers
• CPC Class Codes: H01L 21/28518 the conductive layers comprising silicides H01L21/28537 takes precedence
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/32115 Planarisation
• CPC Class Codes: H01L 21/32135 by vapour etching only
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/67161 characterized by the layout of the process chambers
• CPC Class Codes: H01L 21/67207 comprising a chamber adapted to a particular process
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/7684 Smoothing; Planarisation
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76849 the layer being positioned on top of the main fill metal
• CPC Class Codes: H01L 21/7685 the layer covering a conductive structure H01L21/76849 takes precedence
• CPC Class Codes: H01L 21/76862 : Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76867 : characterized by methods of formation other than PVD, CVD or deposition from a liquids PVD H01L21/2855; CVD H01L21/28556; deposition from liquids H01L21/288
• CPC Class Codes: H01L 21/76871 : Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers
• CPC Class Codes: H01L 21/76879 : by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288

Abstract

The embodiments fill the need to enhance electro-migration performance, provide lower metal resistivity, and improve metal-to-metal interfacial adhesion for copper interconnects by providing improved processes and systems that produce an improved metal-to-metal interface, more specifically barrier-to-copper interface. An exemplary method of preparing a substrate surface of a substrate to deposit a metallic barrier layer to line a copper interconnect structure of the substrate and to deposit a thin copper seed layer on a surface of the metallic barrier layer in an integrated system to improve electromigration performance of the copper interconnect is provided. The method includes cleaning an exposed surface of a underlying metal to remove surface metal oxide in the integrated system, wherein the underlying metal is part of a underlying interconnect electrically connected to the copper interconnect. The method also includes depositing the metallic barrier layer to line the copper interconnect structure in the integrated system, wherein after depositing the metallic barrier layer, the substrate is transferred and processed in controlled environment to prevent the formation of metallic barrier oxide. The method further includes depositing the thin copper seed layer in the integrated system, and depositing a gap-fill copper layer over the thin copper seed layer in the integrated system. An exemplary system to practice the exemplary method described above is also provided.

Claims

1. A method of preparing a substrate surface of a substrate to deposit a metallic barrier layer to line a copper interconnect structure of the substrate and to deposit a thin copper seed layer on a surface of the metallic barrier layer in an integrated system to improve electromigration performance of the copper interconnect, comprising:

cleaning an exposed surface of a underlying metal to remove surface metal oxide in the integrated system, wherein the underlying metal is part of a underlying interconnect electrically connected to the copper interconnect;

depositing the metallic barrier layer to line the copper interconnect structure in the integrated system, wherein after depositing the metallic barrier layer, the substrate is transferred and processed in controlled environment to prevent the formation of metallic barrier oxide;

depositing the thin copper seed layer in the integrated system; and

depositing a gap-fill copper layer over the thin copper seed layer in the integrated system.

2. The method of claim 1, further comprising:

reducing a surface of the metallic barrier layer to convert metallic barrier oxide on the surface of the metallic barrier layer to make the surface of the metallic barrier layer to be metal-rich in the integrated system, wherein reducing the surface of the metallic barrier layer is performed after the exposed surface of the underlying metal is cleaned.

3. The method of claim 2, wherein reducing the surface of the metallic barrier layer is performed by a hydrogen-containing plasma.

4. The method of claim 1, wherein the copper interconnect include a metal line over a via and the underlying interconnect include a metal line.

5. The method of claim 1, wherein the copper interconnect include a metal line and the underlying interconnect include a contact.

6. The method of claim 1, wherein cleaning the exposed surface of the surface metal oxide is accomplished by using one of an Ar sputtering process or a plasma process using a fluorine-containing gas.

8. The method of claim 1, wherein depositing the metallic barrier layer further comprising:

depositing a first metallic barrier layer; and

depositing a second metallic barrier layer.

9. The method of claim 8, wherein depositing the first metallic barrier layer is performed in an atomic layer deposition (ALD) system and depositing the second metallic barrier layer is performed in a physical vapor deposition (PVD) system.

10. The method of claim 8, wherein depositing the first metallic barrier layer is performed in an ALD system and depositing the second metallic barrier layer is performed in a ALD system.

12. The method of claim 1, wherein depositing the gap-fill copper layer is performed in an electrochemical plating (ECP) system.

14. The method of claim 1, wherein systems used to process the substrate enable a dry-in/dry-out processing of the substrate, wherein the substrate goes in and comes out the systems in a dry state.

15. The method of claim 1, wherein the substrate is transferred or processed with limited exposure to oxygen in the integrated system by being transferred or processed in a vacuum environment or in an inert gas filled environment.

16. The method of claim 1, wherein the substrate being transferred and processed in controlled environment to prevent the formation of metallic barrier oxide and to enable the selectively depositing the thin layer of copper seed layer to improve electromigration of the copper interconnect.

17. The method of claim 1, wherein metallic barrier layer is made of Ta, TaN, Ru, or a combination of these materials.

18. The method of claim 1, wherein substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

7. The method of claim 7, wherein the fluorine-containing gas is NF₃, CF₄, or a combination of both.

11. The method of clam 1, wherein selectively depositing the thin copper seed layer is performed in an electroless deposition system.

13. The method of claim 11, wherein depositing the gap-fill copper layer is performed in the electroless deposition system with a chemistry different from that used for the thin copper seed layer deposition.

19. A method of preparing a substrate surface of a substrate to deposit a metallic barrier layer to line a copper interconnect structure of the substrate and to selectively deposit a thin copper seed layer on a surface of the metallic barrier layer in an integrated system to improve electromigration performance of the copper interconnect, comprising:

cleaning an exposed surface of an underlying metal to remove surface oxide in the integrated system, wherein the underlying metal is part of a underlying interconnect, the copper interconnect is electrically connected to underlying interconnect;

depositing the metallic barrier layer to line the copper interconnect structure in the integrated system, wherein after depositing the metallic barrier layer, the substrate is transferred and processed in controlled environment to prevent the formation of metallic barrier oxide;

selectively depositing the thin copper seed layer in the integrated system;

depositing a gap-fill copper layer over the thin copper seed layer in the integrated system in the integrated system;

removing copper overburden and metallic barrier overburden in the integrated system, wherein removing copper overburden and metallic barrier overburden creates the planarized copper surface;

removing metal-organic complex contaminants and metal oxides from the substrate surface in the integrated system;

removing organic contaminants from the substrate surface in the integrated system;

reducing the planarized copper surface that is removed of metal-organic complex contaminants, metal oxides, and organic contaminants in the integrated system; and

depositing a thin layer of a cobalt-alloy material on the reduced planarized copper surface in the integrated system.

20. The method of claim 19, further comprising:

reducing a surface of the metallic barrier layer to convert metallic barrier oxide on the surface of the metallic barrier layer to make the surface of the metallic barrier layer to be metallic-rich in the integrated system, wherein reducing the surface of the metallic barrier layer is performed immediately after the exposed surface of the underlying metal is cleaned.

21. The method of claim 19, wherein removing copper overburden and metallic barrier overburden is accomplished by chemical-mechanical polishing (CMP) or by wet chemical etching.

22. The method of claim 19, wherein the metal-organic complex contaminants include copper-benzotrizole (Cu—

BTA) complex.

23. The method of claim 19, wherein removing metal-organic complex contaminants is performed by using a wet clean with a cleaning solution containing tetramethylammonium chloride (TMAH).

24. The method of claim 19, wherein removing metal-organic complex contaminants is performed by using a wet clean with a cleaning solution containing complexing amines.

25. The method of claim 19, wherein removing metal oxides is performed by using a wet clean with a cleaning solution containing citric acid.

26. The method of claim 19, wherein removing organic contaminants is performed by an oxygen plasma process with process temperature less than about 120°

C. to prevent forming a thick copper oxide layer on the copper surface.

27. The method of claim 19, wherein reducing the planarized copper surface is performed by a hydrogen-containing plasma.

28. The method of claim 19, wherein the cobalt-alloy material is selected from the group consisting of CoWP, CoWB, and CoWBP.

29. The method of claim 19, wherein systems used to process the substrate enable a dry-in/dry-out processing of the substrate, wherein the substrate goes in come out the systems in a dry state.

30. The method of claim 19, wherein the substrate is transferred or processed in controlled environment in the integrated system by being transferred or processed in a vacuum environment or in an inert gas filled environment.

31. The method of claim 19, wherein the substrate being transferred and processed in controlled environment to prevent the formation of metallic barrier oxide and copper oxide enables selectively depositing the thin layer of copper seed layer on the metallic barrier layer and selectively depositing the thin layer of the cobalt-alloy material on the reduced planarized copper surface to improve electromigration of the copper interconnect.

32. The method of claim 19, wherein metallic barrier layer is made of Ta, TaN, or a combination of both.

33. The method of claim 19, wherein substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

34. A method of preparing a metallic barrier surface of a substrate to deposit a thin copper seed layer on a surface of a metallic barrier layer of a copper interconnect structure in an integrated system to improve electromigration performance of the copper interconnect structure, comprising:

reducing a surface of the metallic barrier layer to convert metallic barrier oxide on the surface of the metallic barrier layer to make the surface of the metallic barrier layer to be metallic-rich in the integrated system;

depositing the thin copper seed layer in the integrated system; and

depositing a gap-fill copper layer over the thin copper seed layer in the integrated system.

35. An integrated system for processing a substrate in controlled environment to enable deposition of a thin copper seed layer on a surface of a metallic barrier layer of a copper interconnect, comprising:

a lab-ambient transfer chamber capable of transferring the substrate from a substrate cassette coupled to the lab-ambient transfer chamber into the integrated system;

a vacuum transfer chamber operated under vacuum at a pressure less than 1 Torr, wherein at least one vacuum process module is coupled to the vacuum transfer chamber;

a vacuum process module for cleaning an exposed surface of a metal oxide of a underlying metal in the integrated system, wherein the underlying metal is part of a underlying interconnect, the copper interconnect is electrically connected to the underlying interconnect, wherein the vacuum process module for cleaning is one of the at least one vacuum process module coupled to the vacuum transfer chamber, and is operated under vacuum at a pressure less than 1 Torr;

a vacuum process module for depositing the metallic barrier layer, wherein the vacuum process module for depositing the metallic barrier layer one of the at least one vacuum process module is coupled to the vacuum transfer chamber, and is operated under vacuum at a pressure less than 1 Torr;

a controlled-ambient transfer chamber filled with an inert gas selected from a group of inert gases, wherein at least one controlled-ambient process module is coupled to the controlled-ambient transfer chamber; and

an electroless copper deposition process module used to deposit the thin layer of copper seed layer on the surface of the metallic barrier layer, wherein the electroless copper deposition process module is one of the at least one controlled environment process modules coupled to the controlled-ambient transfer chamber.

36. The integrated system of claim 35, further comprising:

a hydrogen-containing reduction process module used to reduce metal oxide or metal nitride on the surface of the metallic barrier, wherein the hydrogen-containing reduction process module is coupled to the vacuum transfer chamber, the hydrogen-containing reduction process module is operated under vacuum at a pressure less than 1 Torr.

37. The integrated system of claim 35, wherein the electroless copper deposition process module is also used to deposit a gap-fill copper layer over the thin copper seed layer.

38. The integrated system of claim 35, wherein another electroless copper deposition process module is used to deposit a gap-fill copper layer over the thin copper seed layer.

39. The integrated system of claim 35, further comprising:

a substrate cleaning process module used to clean the substrate surface after depositing the gap-fill copper layer over the thin layer copper seed layer, the substrate cleaning process module is one of the at least one vacuum process module coupled to the controlled-ambient transfer module.

40. The integrated system of claim 35, further comprising:

a first loadlock coupled to the vacuum transfer chamber and the controlled-ambient transfer chamber, wherein the first loadlock assists the substrate to be transferred between the vacuum transfer chamber and the controlled-ambient transfer chamber, the first loadlock being configured to be operated under vacuum at pressure less than 1 Torr or to be filled with an inert gas selected from a group of inert gases; and

a second loadlock coupled to the vacuum transfer chamber and the lab-ambient transfer chamber, wherein the second loadlock assists the substrate to be transferred between the vacuum transfer chamber and the lab-ambient transfer chamber, the second loadlock being configured to be operated under vacuum at pressure less than 1 Torr or at lab ambient or to be filled with an inert gas selected from a group of inert gases.

41. The integrated system of claim 35, wherein the vacuum transfer chamber and the at least one vacuum process module coupled to the vacuum transfer chamber are operated at a pressure less than 1 Torr to control the exposure of the substrate to oxygen.

42. The integrated system of claim 35, wherein the controlled-ambient transfer chamber and each one the at least one process module coupled to the controlled-ambient transfer chamber are filled with one or more inert gases selected from the group of inert gases to control the exposure of the substrate to oxygen.

43. The integrated system of claim 35, wherein substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

44. The method of claim 43, wherein limiting the exposure of the substrate surface to oxygen enables the thin layer of copper seed layer being selectively deposited on the surface of the metallic barrier layer.

45. The integrated system of claim 35, wherein the at least one process module coupled to the controlled-ambient transfer module enables a dry-in/dry-out processing of the substrate, wherein the substrate goes in and comes out the at least one process module in a dry state.

46. The integrated system of claim 45, wherein the electroless copper deposition process module is coupled to a rinse and dry system to enable the dry-in/dry-out processing.

47. An integrated system for processing a substrate in controlled environment to enable selective deposition of a thin copper seed layer on a surface of a metallic barrier layer of a copper interconnect and preparing a planarized copper surface of the copper interconnect to selectively depositing a thin layer of a cobalt-alloy material in an integrated system to improve electromigration performance of the copper interconnect, comprising:

a lab-ambient transfer chamber capable of transferring the substrate from a substrate cassette coupled to the lab-ambient transfer chamber into the integrated system;

a vacuum transfer chamber operated under vacuum at a pressure less than 1 Torr, wherein at least one vacuum process module is coupled to the vacuum transfer chamber;

an Ar sputtering process module to clean an exposed surface of a metal oxide of a underlying metal in the integrated system, wherein the underlying metal is part of a underlying interconnect, the copper interconnect is electrically connected to the underlying interconnect, the Ar sputtering process module one of the at least one vacuum process module is coupled to the vacuum transfer chamber;

an atomic layer deposition (ALD) process module for depositing a thin first metallic barrier layer, wherein the ALD process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber;

a PVD process chamber for depositing a thin second metallic barrier layer, wherein the PVD process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber;

a hydrogen reduction process module for reducing a metal oxide or metal nitride to a metal, wherein the hydrogen reduction process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber;

an oxygen plasma process module for removing organic contaminants from the substrate surface, wherein the oxygen plasma process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber;

a controlled-ambient transfer chamber filled with an inert gas selected from a group of inert gases, wherein at least one controlled-ambient process module is coupled to the controlled-ambient transfer chamber;

an electroless copper deposition process module used to deposit the thin layer of copper seed layer and a gap-fill copper layer on the surface of the metallic barrier layer, the electroless copper deposition process module being one of the at least one controlled-ambient process module coupled to the controlled-ambient transfer chamber;

an electroless cobalt-alloy deposition process module used to deposit the thin layer of the cobalt-alloy material on the prepared planarized copper surface, the electroless copper alloy deposition process module being one of the at least one controlled-ambient process module coupled to the controlled-ambient transfer chamber;

a planarizing process module used to remove a copper overburden and a barrier overburden of the copper interconnect, the planarizing process module is one of the at least one controlled-ambient process module coupled to the controlled-ambient transfer module; and

a wet clean process module used to remove metallic contamination on the substrate surface, the wet clean process module is one of the at least one controlled-ambient process module coupled to the controlled-ambient transfer module.

48. The integrated system of claim 47, further comprising:

a substrate cleaning process module used to clean the substrate surface after depositing and planarizing the gap-fill copper layer over the thin layer copper seed layer and after depositing the thin layer of the cobalt-alloy material, the substrate cleaning process module being one of the at least one controlled-ambient process module coupled to the controlled-ambient transfer module.

49. The integrated system of claim 47, further comprising:

a first loadlock coupled to the vacuum transfer chamber and the controlled-ambient transfer chamber, wherein the first loadlock assists the substrate to be transferred between the vacuum transfer chamber and the controlled-ambient transfer chamber, the first loadlock being configured to be operated under vacuum at pressure less than 1 Torr or to be filled with an inert gas selected from a group of inert gases to operated under the same pressure as the controlled-ambient transfer module; and

a second loadlock coupled to the vacuum transfer chamber and the lab-ambient transfer chamber, wherein the second loadlock assists the substrate to be transferred between the vacuum transfer chamber and the lab-ambient transfer chamber, the second loadlock being configured to be operated under vacuum at pressure less than 1 Torr or at lab ambient or to be filled with an inert gas selected from a group of inert gases to operated under the same pressure as the controlled-ambient transfer module.

50. The integrated system of claim 47, wherein the controlled-ambient transfer chamber and each one the at least one controlled-ambient process module coupled to the controlled-ambient transfer chamber are filled with one or more inert gas selected from the group of inert gases to limit the exposure of the substrate to oxygen.

51. The integrated system of claim 47, wherein substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

52. The integrated system of claim 47, wherein limiting the exposure of the substrate surface to oxygen enables the thin layer of copper seed layer being selectively deposited on the surface of the metallic barrier layer.

53. The integrated system of claim 47, wherein the at least one process module coupled to the controlled-ambient transfer module enables a dry-in/dry-out processing of the substrate, wherein the substrate goes in and comes out the at least one process module in a dry state.

54. An integrated system for processing a substrate in controlled environment to enable deposition of a thin copper seed layer on a surface of a metallic barrier layer of a copper interconnect, comprising:

a lab-ambient transfer chamber capable of transferring the substrate from a substrate cassette coupled to the lab-ambient transfer chamber into the integrated system;

a vacuum transfer chamber operated under vacuum at a pressure less than 1 Torr, wherein at least one vacuum process module is coupled to the vacuum transfer chamber;

a vacuum process module for reducing the metallic barrier layer, wherein the vacuum process module for reducing the metallic barrier layer one of the at least one vacuum process module is coupled to the vacuum transfer chamber, and is operated under vacuum at a pressure less than 1 Torr;

a controlled-ambient transfer chamber filled with an inert gas selected from a group of inert gases, wherein at least one controlled-ambient process module is coupled to the controlled-ambient transfer chamber; and

an electroless copper deposition process module used to deposit the thin layer of copper seed layer on the surface of the metallic barrier layer, wherein the electroless copper deposition process module is one of the at least one controlled environment process modules coupled to the controlled-ambient transfer chamber.