Apparatus and method for electrochemically depositing metal on a semiconductor workpiece

• US 20020008034A1
• Filed: 12/07/2000
• Published: 01/24/2002
• Est. Priority Date: 03/20/1998
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: Ritzdorf, Thomas L., McHugh, Paul R., Wilson, Gregory J., Weaver, Robert A., Chen, Linlin
• Granted Patent: US 6,565,729 B2
• Time in Patent Office: Days
• US Class Current: 205/82
• CPC Class Codes: C25D 17/02 Tanks; Installations therefor
• CPC Class Codes: C25D 17/10 Electrodes , e.g. composition, counter electrode
• CPC Class Codes: C25D 17/12 Shape or form C25D17/14 takes precedence
• CPC Class Codes: C25D 3/38 of copper
• CPC Class Codes: C25D 5/08 Electroplating with moving electrolyte e.g. jet electroplating using locally applied jets of electrolyte C25D5/026
• CPC Class Codes: C25D 5/10 Electroplating with more than one layer of the same or of different metals for bearings C25D7/10
• CPC Class Codes: C25D 5/50 by heat-treatment
• CPC Class Codes: C25D 5/67 Electroplating to repair workpiece
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/2885 using an external electrical current, i.e. electro-deposition
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76868 Forming or treating discontinuous thin films, e.g. repair, enhancement or reinforcement of discontinuous thin films
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 2221/1089 Stacks of seed layers
• CPC Class Codes: Y10S 204/07 Current distribution within the bath
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]

Abstract

A process for metallization of a workpiece, such as a semiconductor workpiece. In an embodiment, an alkaline electrolytic copper bath is used to electroplate copper onto a seed layer, electroplate copper directly onto a barrier layer material, or enhance an ultra-thin copper seed layer which has been deposited on the barrier layer using a deposition process such as PVD. The resulting copper layer provides an excellent confirm copper coating that fills trenches, vias, and other microstructures in the workpiece. When used for seed layer enhancement, the resulting copper seed layer provide an excellent conformal copper coating that allows the microstructures to be filled with a copper layer having good uniformity using electrochemical deposition techniques. Further, copper layers that are electroplated in the disclosed manner exhibit low sheet resistance and are readily annealed at low temperatures.

Claims

1. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer within a principal fluid chamber of a reactor to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process, comprising supplying electroplating power to a plurality of concentric anodes disposed at different positions within the principal fluid flow chamber relative to the workpiece; and

(b) electrolytically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

2. The process of claim 1 wherein the additional metal is copper.

3. The process of claim 1 wherein the ultra-thin seed layer is formed on a barrier layer deposited on a surface of the workpiece.

4. The process of claim 1 wherein the first electrochemical deposition step occurs in an alkaline bath.

5. The process of claim 4 wherein the alkaline bath comprises metal ions and an agent effective in complexing the metal ions.

6. The process of claim 1 wherein the ultra-thin metal seed layer that is repaired is formed by physical vapor deposition.

7. The process of claim 1 wherein the ultra-thin metal seed layer that is repaired has a thickness of less than or equal to 500 Angstroms.

8. The process of claim 7 wherein the ultra-thin metal layer that is repaired has a thickness of 100 to 250 Angstroms.

9. The process of claim 1 wherein the complexing agent comprises one or more complexing agents selected from EDTA, ED, and polycarboxylic acid.

10. The process of claim 9 wherein the complexing agent comprises EDTA and the EDTA in the bath has a concentration within the range of 0.03 to 1.0 M.

11. The process of claim 10 wherein the complexing agent comprises ED and wherein the ED in the electrolytic bath has a concentration within the range of 0.03 to 1.0 M.

12. The process of claim 10 wherein the complexing agent comprises citric acid and the citric acid in the bath has a concentration within the range of 0.03 to 1.0 M.

13. The process of claim 1 wherein the step of subjecting the workpiece to a further electrochemical deposition process occurs in an acidic electrolytic solution to complete deposition of the metal to a thickness needed for the formation of the interconnect structure.

14. The process of claim 13, further comprising subjecting the workpiece to a rinsing process after electrochemical deposition in the alkaline bath and prior to the further electrochemical metal deposition process in an acidic electrolytic solution.

15. The process of claim 1, wherein the enhanced seed layer has a thickness at all points on sidewalls of substantially all recessed features distributed within the workpiece that is equal to or greater than 10% of the enhanced seed layer thickness over the exteriorly disposed surface of the workpiece.

16. The process of claim 1, wherein one or more of the plurality of concentric anodes used to repair the ultra-thin metal seed layer is disposed in close proximity to the workpiece.

17. The process of claim 1, wherein the plurality of concentric anodes used for the repair of the ultra-thin metal seed layer are arranged at varying distances from the workpiece from an innermost one of the plurality of concentric anodes to an outermost one of the plurality of concentric anodes.

19. The process of claim 1, wherein one or more of the plurality of concentric anodes used to repair the ultra-thin metal seed layer is a virtual anode.

20. The process of claim 19, wherein the virtual anode used in the repair of the ultra-thin metal seed layer comprises an anode chamber housing having a processing fluid inlet and a processing fluid outlet, the processing fluid outlet being disposed in close proximity to the workpiece, and at least one conductive anode element disposed in the anode chamber housing.

21. The process of claim 20, wherein the at least one conductive anode element is formed from an inert material.

22. The process of claim 1, wherein the repair of the ultra-thin metal seed layer is further carried out by providing a plurality of nozzles within the reactor that are disposed to provide a flow of a processing fluid to the principal fluid flow chamber, the plurality of nozzles being arranged and directed to provide vertical and radial fluid flow components that combine to generate a substantially uniform normal flow component oriented radially across a surface of the workpiece on which the ultra-thin metal seed layer is formed.

23. The process of claim 1, wherein the principal fluid chamber in which the repair of the ultra-thin metal seed layer is carried out is defined in an upper portion thereof by an angled wall, the angled wall supporting one or more of the plurality of the concentric anodes.

24. The process of claim 1, wherein the repair of the ultra-thin metal seed layer is carried out in a principal fluid flow chamber that comprises an inlet disposed at a lower portion thereof and that is configured to provide a venturi effect that facilitates recirculation of a chemical processing fluid in a lower portion of the principal fluid flow chamber.

25. The process of claim 1, wherein during the repair of the ultra-thin metal seed layer, at least two of the plurality of anodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two of the plurality of anodes.

26. The process of claim 25, wherein the controlling of the supply of power for at least one of the independently controlled anodes is based on one or more user input parameters and a plurality of predetermined sensitivity values associated with the workpiece, the predetermined sensitivity values corresponding to process perturbations resulting from perturbations of an electrical power supply parameter for the at least one independently controlled electrode.

27. The process of claim 26, wherein the electrical power parameter is electrical current.

28. The process of claim 26, wherein the sensitivity values are logically arranged within a controller as one or more Jacobian matrices.

29. The process of claim 26, wherein the at least one user input parameter comprises a thickness of the additional metal to be deposited on the ultra-thin metal seed layer.

30. The product produced by the process of claim 1.

39. The process of claim 26, wherein the at least one user input parameter comprises a thickness of the additional metal to be deposited on the ultra-thin metal seed layer.

47. The process of claim 26, wherein the controlling of the supply of power for a given one of the independently controlled electrodes is based on one or more user input parameters and the plurality of predetermined sensitivity values associated with the workpiece, the predetermined sensitivity values corresponding to process perturbations resulting from perturbations of an electrical power supply parameter for the at least one independently controlled electrode.

48. The process of claim 47, wherein the sensitivity values are logically arranged within a controller as one or more Jacobian matrices.

49. The process of claim 47, wherein the at least one user input parameter comprises a thickness of the additional metal to be deposited on the ultra-thin metal seed layer.

18. The process of claim 18, wherein the plurality of concentric anodes used for the repair of the ultra-thin metal seed layer are arranged at increasing distances from the workpiece from an innermost one of the plurality of concentric anodes to an outermost one of the plurality of concentric anodes.

31. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer within a principal fluid chamber of a reactor to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process, comprising supplying electroplating power to a plurality of electrodes within the principal fluid flow chamber, wherein at least two of the plurality of electrodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two electrodes during repair of the ultra-thin metal seed layer; and

(b) electrolytically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

32. The process of claim 31 wherein the additional metal is copper.

33. The process of claim 31 wherein the ultra-thin seed layer is formed on a barrier layer deposited on a surface of the workpiece.

34. The process of claim 31 wherein the electrochemical deposition step occurs in an alkaline bath.

35. The process of claim 31 wherein the ultra-thin metal seed layer that is repaired has a thickness of less than or equal to 500 Angstroms.

36. The process of claim 31, wherein the controlling of the supply of power for at least one of the independently controlled electrodes is based on one or more user input parameters and a plurality of predetermined sensitivity values associated with the workpiece, the predetermined sensitivity values corresponding to process perturbations resulting from perturbations of an electrical power supply parameter for the at least one independently controlled electrode.

37. The process of claim 36, wherein the electrical power parameter is electrical current or potential.

38. The process of claim 36, wherein the sensitivity values are logically arranged within a controller as one or more Jacobian matrices.

40. The product produced by the process of claim 31.

41. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrochemical deposition of a metal thereon on the metal seed layer, comprising:

(a) subjecting the workpiece to an electrochemical deposition process that is different from the first deposition process, in an alkaline electroplating bath comprising metal ions complexed with a complexing agent such that additional metal is deposited on the ultra-thin copper seed layer to thereby repair the seed layer, resulting in an enhanced seed layer, the second deposition process being carried out by supplying electroplating power to a plurality of concentric anodes disposed at different positions, relative to the workpiece, within a principal fluid flow chamber of a reactor; and

(b) electrolytically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

42. The process of claim 41 wherein the additional metal is copper.

43. The process of claim 41 wherein the ultra-thin seed layer is formed on a barrier layer deposited on a surface of the workpiece.

44. The process of claim 41 wherein the complexing agent comprises one or more complexing agents selected from EDTA, ED, and polycarboxylic acid.

45. The process of claim 41 wherein the ultra-thin metal seed layer that is repaired has a thickness of less than or equal to 500 Angstroms.

46. The process of claim 41, wherein during the repair of the ultra-thin metal seed layer, at least two of the plurality of anodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two of the plurality of anodes.

50. The product produced by the process of claim 41.

51. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrochemical deposition of a metal thereon on the metal seed layer, comprising:

(a) subjecting the workpiece to an electrochemical deposition process that is different from the first deposition process, in an alkaline electroplating bath comprising metal ions complexed with a complexing agent such that additional metal is deposited on the ultra-thin copper seed layer to thereby repair the seed layer, resulting in an enhanced seed layer, comprising supplying electroplating power to a plurality of electrodes within the principal fluid flow chamber, wherein at least two of the plurality of electrodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two electrodes during repair of the ultra-thin metal seed layer; and

(b) electrolytically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

52. The process of claim 51 wherein the additional metal is copper.

53. The process of claim 51 wherein the ultra-thin seed layer is formed on a barrier layer deposited on a surface of the workpiece.

54. The process of claim 51 wherein the complexing agent comprises one or more complexing agents selected from EDTA, ED, and polycarboxylic acid.

55. The process of claim 51 wherein the ultra-thin metal seed layer that is repaired has a thickness of less than or equal to 500 Angstroms.

56. The process of claim 51, wherein the controlling of the supply of power for at least one of the independently controlled electrodes is based on one or more user input parameters and a plurality of predetermined sensitivity values associated with the workpiece, the predetermined sensitivity values corresponding to process perturbations resulting from perturbations of an electrical power supply parameter for the at least one independently controlled electrode.

57. The process of claim 56, wherein the electrical power parameter is electrical current.

58. The process of claim 56, wherein the sensitivity values are logically arranged within a controller as one or more Jacobian matrices.

59. The process of claim 56, wherein the at least one user input parameter comprises a thickness of the additional metal to be deposited on the ultra-thin metal seed layer.

60. The product produced by the process of claim 51.

61. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer within a principal fluid chamber of a reactor to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process, comprising exposing the workpiece to an electroplating solution within a fluid flow chamber of a reactor, the fluid flow chamber defining a sidewall and a plurality of nozzles disposed in the sidewall and arranged and directed to provide vertical and radial fluid flow components that combine to create a substantially uniform normal flow component radially across a surface of the workpiece on which the ultra-thin metal seed layer is formed; and

(b) electrochemically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

62. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrochemical deposition of a metal thereon on the metal seed layer, comprising:

(a) subjecting the workpiece to an electrochemical deposition process that is different from the first deposition process, in an alkaline electroplating bath comprising metal ions complexed with a complexing agent such that additional metal is deposited on the ultra-thin copper seed layer to thereby repair the seed layer, resulting in an enhanced seed layer, comprising exposing the workpiece to an electroplating solution within a fluid flow chamber of a reactor, the fluid flow chamber defining a sidewall and a plurality of nozzles disposed in the sidewall and arranged and directed to provide vertical and radial fluid flow components that combine to create a substantially uniform normal flow component radially across a surface of the workpiece on which the ultra-thin metal seed layer is formed; and

(b) electrochemically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer.

63. The process of claim 62, further comprising applying heat to the metallization interconnect structure after the first electrochemical deposition process to further anchor the seed layer to the underlying layer.

64. The process of claim 62, wherein the first electrochemical deposition process involves depositing a metal alloy including an element that will preferentially be deposited at interfaces defined between differing materials.

65. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer within a principal fluid chamber of a reactor to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process; and

(b) electrolytically depositing a metal on the enhanced seed layer under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer, comprising supplying electroplating power to a plurality of concentric anodes disposed at different positions within the principal fluid flow chamber relative to the workpiece.

66. The process of claim 65, wherein the second deposition process that repairs the seed layer is an electroless plating process.

67. The process of claim 65, wherein the second deposition process that repairs the said layer also comprises supplying electroplating power to a plurality of concentric anodes disposed at different positions within the principal fluid flow chamber relative to the workpiece.

68. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process; and

(b) electrolytically depositing a metal on the enhanced seed layer within a principal fluid chamber of a reactor under conditions in which the deposition rate of the electrolytic deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer, comprising supplying electroplating power to a plurality of electrodes within the principal fluid flow chamber, wherein at least two of the plurality of electrodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two electrodes during deposition.

69. The process of claim 68, wherein the second deposition process that repairs the seed layer is an electroless plating process.

70. The process of claim 68, wherein the second deposition process that repairs the said layer occurs within a principal fluid chamber of a reactor and also comprises supplying electroplating power to a plurality of electrodes within the principal fluid flow chamber, wherein at least two of the plurality of electrodes are independently connected to an electrical power supply, further comprising independently controlling the supply of electrical power to the at least two electrodes during deposition.

71. A process for applying a metallization interconnect structure to a workpiece on which an ultra-thin metal seed layer has been formed using a first deposition process, the first deposition process anchoring the ultra-thin metal seed layer to an underlying layer, the ultra-thin metal seed layer having physical characteristics that render it generally unsuitable for bulk electrolytic deposition of a metal thereon on the metal seed layer, comprising:

(a) repairing the ultra-thin metal seed layer by electrochemically depositing additional metal on the ultra-thin metal seed layer to provide an enhanced seed layer using a second deposition process, that is different from the first deposition process; and

(b) electrochemically depositing a metal on the enhanced seed layer within a principal fluid chamber of a reactor within a principal fluid chamber of a reactor under conditions in which the deposition rate of the deposition process is substantially greater than the deposition rate of the process used to repair the metal seed layer, comprising exposing the workpiece to an electroplating solution within a fluid flow chamber of a reactor, the fluid flow chamber defining a sidewall and a plurality of nozzles disposed in the sidewall and arranged and directed to provide vertical and radial fluid flow components that combine to create a substantially uniform normal flow component radially across a surface of the workpiece on which the ultra-thin metal seed layer is formed.

72. The process of claim 71, wherein the second deposition process that repairs the seed layer is an electroless plating process.

73. The process of claim 71, wherein the second deposition process that repairs the said layer occurs within a principal fluid chamber of a reactor and also comprises exposing the workpiece to an electroplating solution within a fluid flow chamber of a reactor, the fluid flow chamber defining a sidewall and a plurality of nozzles disposed in the sidewall and arranged and directed to provide vertical and radial fluid flow components that combine to create a substantially uniform normal flow component radially across a surface of the workpiece on which the ultra-thin metal seed layer is formed.