Radical processing of a sub-nanometer insulation film

• US 20030170945A1
• Filed: 12/06/2002
• Published: 09/11/2003
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Takahashi, Tsuyoshi, Aoyama, Shintaro, Shinriki, Hiroshi, Igeta, Masanobu
• Granted Patent: US 6,927,112 B2
• Time in Patent Office: Days
• US Class Current: 438/200
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: C23C 16/405 of refractory metals or yttrium
• CPC Class Codes: C23C 16/482 using incoherent light, UV to IR, e.g. lamps
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/02238 silicon in uncombined form, i.e. pure silicon
• CPC Class Codes: H01L 21/02249 formation by combined oxidation and nitridation performed simultaneously
• CPC Class Codes: H01L 21/02255 formation by thermal treatment H01L21/02252 takes precedence; after treatment of an insulating film H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/02332 into an oxide layer, e.g. changing SiO to SiON
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/31155 by ion implantation
• CPC Class Codes: H01L 21/3144 on silicon
• CPC Class Codes: H01L 21/3145 formed by deposition from a gas or vapour
• CPC Class Codes: H01L 21/316 composed of oxides or glassy oxides or oxide based glass
• CPC Class Codes: H01L 21/31641 Deposition of Zirconium oxides, e.g. ZrO2
• CPC Class Codes: H01L 21/31645 Deposition of Hafnium oxides, e.g. HfO2
• CPC Class Codes: H01L 21/31662 of silicon in uncombined form
• CPC Class Codes: H01L 21/67017 Apparatus for fluid treatment H01L21/67126, H01L21/6715 take precedence
• CPC Class Codes: H01L 29/513 : the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 : the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/518 : the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material

Abstract

A method of nitriding an insulation film, includes the steps of forming nitrogen radicals by high-frequency plasma, and causing nitridation in a surface of an insulation film containing therein oxygen, by supplying the nitrogen radicals to the surface of the insulation film.

Claims

1. A method of nitriding an insulation film, comprising the steps of:

forming nitrogen radicals by high-frequency plasma; and

causing nitridation in a surface of an insulation film containing therein oxygen, by supplying said nitrogen radicals to said surface of said insulation film.

2. The method as claimed in claim 1, wherein said insulation film is an oxide film.

3. The method as claimed in claim 2, wherein said oxide film has a thickness of 0.4 nm or less.

4. The method as claimed in claim 1, wherein said insulation film is an oxynitride film.

5. The method as claimed in claim 1, wherein said nitrogen radicals are supplied in the form of being carried by a gas flow formed along said surface of said insulation film.

6. The method as claimed in claim 5, wherein said gas flow is caused to flow from a first side of a substrate formed with said insulation film to a second, diametrically opposite side to said first side.

7. The method as claimed in claim 6, wherein said gas flow is evacuated at said second side of said substrate.

8. The method as claimed in claim 1, wherein said step of forming said nitrogen radicals comprises the steps of:

exciting a nitrogen gas with said high-frequency plasma; and

removing nitrogen ions formed with excitation of said nitrogen gas with any of a diffusion plate or an ion filter.

9. The method as claimed in claim 1, wherein said high-frequency plasma is formed by exciting said nitrogen gas with a frequency of about 400 kHz.

10. The method as claimed in claim 1, wherein said step of nitriding said surface of said insulation film is conducted under a pressure in the range of 0.67 Pa-1.33 kPa.

11. The method as claimed in claim 1, further comprising, prior to said step of supplying said nitrogen radicals to said surface of said insulation film, the step of purging a process space in which said insulation film is held to a pressure lower than a pressure used in said nitridation step.

12. The method as claimed in claim 11, wherein said purging step is conducted so as to evacuate said process space to a pressure of 1.33×

10<sup>−

1</sup>-1.33×

10<sup>−

4</sup> Pa.

13. The method as claimed in claim 1, wherein said insulation film has a thickness of about 0.4 nm.

14. The method as claimed in claim 1, wherein said insulation film is an oxide film formed by processing a surface of a silicon substrate with oxygen radicals excited by ultraviolet radiation.

15. A method of fabricating a semiconductor device, comprising the steps of:

forming an insulation film on a silicon substrate surface;

forming nitrogen radicals with high-frequency plasma;

nitriding a surface of said insulation film by supplying said nitrogen radicals to said surface of said insulation film; and

forming a high-K dielectric film on said insulation film having said surface subjected to nitridation.

16. The method as claimed in claim 15, wherein said insulation film is an oxide film.

17. The method as claimed in claim 16, wherein said oxide film has a thickness of 0.4 nm or less.

18. The method as claimed in claim 15, wherein said insulation film is an oxynitride film.

19. The method as claimed in claim 15, wherein said nitrogen radicals are supplied in the form of being carried by a gas flow formed along said surface of said insulation film.

20. The method as claimed in claim 19, wherein said gas flow is caused to flow from a first side of said silicon substrate, on which said insulation film is formed, to a second, diametrically opposite side to said first side.

21. The method as claimed in claim 20, wherein said gas flow is evacuated at said second side of said substrate.

22. The method as claimed in claim 15, wherein said step of forming said nitrogen radicals comprises the steps of:

exciting a nitrogen gas by said high-frequency plasma; and

removing nitrogen ions formed with excitation of said nitrogen gas by an ion filter.

23. The method as claimed in claim 15, wherein said high-frequency plasma is excited at a frequency of about 400 kHz.

24. The method as claimed in claim 15, wherein said nitridation step of said surface of said insulation film is conducted under a pressure in the range of 0.67 Pa-1.33 kPa.

25. The method as claimed in claim 15, further comprising, prior to said step of supplying said nitrogen radicals to said surface of said insulation film, the step of purging a process space in which said insulation film is held to a pressure lower than a pressure used in said nitridation step.

26. The method as claimed in claim 25, wherein said purging step is conducted so as to evacuate said process space to a pressure of 1.33×

10<sup>−

1</sup>-1.33×

10<sup>−

4</sup> Pa.

27. The method as claimed in claim 15, wherein said insulation film has a thickness of about 0.4 nm.

28. The method as claimed in claim 15, wherein said step of forming said insulation film comprises the step of processing said surface of said silicon substrate with oxygen radicals excited by ultraviolet radiation.

29. The method as claimed in claim 15, wherein said step of forming said insulation film and said nitridation step of said insulation film are conducted consecutively in the same processing apparatus, without exposing said silicon substrate to the air.

30. The method as claimed in claim 15, wherein said step of forming said insulation film and said step of nitriding said insulation film are conducted consecutively in the same processing apparatus without exposing said silicon substrate to the air, and wherein there is provided a purging step purging a process space in which said insulation film is held between said step of forming said insulation film and said nitridation step of said insulation film, such that said purging step is conducted 0-4 times.

31. A substrate processing apparatus, comprising:

a nitrogen radical formation unit forming nitrogen radicals with high-frequency plasma; and

a processing vessel holding a substrate formed with an insulation film,

said processing vessel causing nitridation of a surface of said insulation film by being supplied with said nitrogen radicals form said nitrogen radical formation unit and supplying said nitrogen radicals to said surface of said insulation film.

32. The substrate processing apparatus as claimed in claim 31, wherein said processing vessel carries said nitrogen radical formation unit on a sidewall surface thereof, said processing vessel supplying said nitrogen radicals to said surface of said insulation film in the form of being carried by a gas flow caused to flow along said surface of said insulation film.

33. The substrate processing apparatus as claimed in claim 32, wherein said gas flow is formed in said processing vessel so as to flow from a first side of said substrate formed with said insulation film to a second, diametrically opposite side to said first side.

34. The substrate processing apparatus as claimed in claim 33, wherein said processing vessel is evacuated at said second side of said substrate.

35. The substrate processing apparatus as claimed in claim 31, wherein said radical formation unit comprises a gas passage and a high-frequency plasma formation part formed in a part of said gas passage for causing plasma excitation in a nitrogen gas flowing through said gas passage.

36. The substrate processing apparatus as claimed in claim 35, wherein said high-frequency plasma formation unit causes said plasma excitation of said nitrogen gas at a frequency of 400-500 kHz.

37. The substrate processing apparatus as claimed in claim 31, wherein said processing vessel is connected with an evacuation system capable of evacuating an interior space of said processing vessel to a pressure lower than a pressure used in said nitridation step of said insulation film surface.

38. A substrate processing apparatus, comprising:

a processing vessel defining a process space, said processing vessel accommodating a stage holding a substrate in said process space;

a first radical source provided on said processing vessel at a side of a first end of said processing vessel with respect to said stage;

a second radical source provided on said processing vessel at a side of said first end of said processing vessel with respect to said stage;

a first evacuation path provided on said processing vessel at a side of a second end of said processing vessel opposite to said first end, said first evacuation path evacuating said process space to a first process pressure; and

a second evacuation path provided on said processing vessel at a side of said second end of said processing vessel, said second evacuation path evacuating said process space to a second process pressure.

39. The substrate processing apparatus as claimed in claim 38, wherein said first evacuation path is activated in the state when said first radical source is activated, and wherein said second evacuation path is activated in the state when said second radical source is activated.

40. The substrate processing apparatus as claimed in claim 38, wherein said first radical source includes an ultraviolet source exciting an oxygen gas supplied to said processing vessel, and wherein said second radical source comprises a remote plasma source supplied with a nitrogen gas and causing excitation of said nitrogen gas.

41. The substrate processing apparatus as claimed in claim 40, wherein said first radical source includes a nozzle causing to flow said oxygen gas along , a surface of said substrate held on said stage, and wherein said ultraviolet source is provided between said nozzle and said substrate so as to cause excitation of said oxygen gas through an optical window.

42. The substrate processing apparatus as claimed in claim 38, wherein said first evacuation path includes a turbo molecular pump.

43. The substrate processing apparatus as claimed in claim 38, wherein said second evacuation path includes a mechanical booster pump.

44. The substrate processing apparatus as claimed in claim 42, wherein said turbo molecular pump is boosted by a mechanical booster pump.

45. The substrate processing apparatus as claimed in claim 38, wherein said processing vessel has a substrate load/unload gate at said second end.

46. The substrate processing apparatus as claimed in claim 38, wherein both of said first evacuation path and said second evacuation path evacuate said process space via an evacuation port provided in said processing vessel in the vicinity of said second end.

47. The substrate processing apparatus as claimed in claim 46, wherein said first evacuation path includes a turbo molecular pump connected to said process space via said evacuation port.

48. The substrate processing apparatus as claimed in claim 38, wherein said state is provided rotatably and wherein said substrate processing apparatus further comprises a rotating mechanism rotating said stage.

49. A substrate processing apparatus, comprising:

a processing vessel defining a process space, said processing vessel accommodating a state holding a substrate in said process space;

a first radical source provided on said processing vessel;

a second radical source provided on said processing vessel;

a first evacuation path provided on said processing vessel, said first evacuation path evacuating said process space to a first process pressure; and

a second evacuation path provided on said processing vessel, said second evacuation path evacuating said process space to a second process pressure,

wherein said first processing path is provided so as to evacuate said process space at a side opposite to said first radical source with respect to said substrate on said stage, and wherein said second evacuation path is provided so as to evacuate said process space at a side opposite to said second radical source with respect to said substrate on said stage.

50. A cluster-type substrate processing apparatus, comprising:

a substrate transfer chamber; and

a plurality of process chambers connected to said substrate transfer chamber,

one of said plurality of process chambers comprising;

a processing vessel having a substrate load/unload opening at a first end thereof in connection with said substrate transfer chamber and a first radical source at a second end opposite to said first end, said processing vessel defining a process space therein;

a stage provided in said process space between said first end and said second end in a rotatable manner, said stage holding a substrate thereon;

a first process gas inlet provided in said process space between said first end and said stage, said first process gas inlet introducing a first process gas into said process space;

a second radical source provided on said processing vessel so as to cause excitation of said fist process gas between said first gas inlet and said stage;

a first evacuation port provided in said process space at a part closer to said first end with respect to said stage;

a second evacuation port provided in said process space at a side closer to said second end with respect to said stage;

a first pump connected to said first evacuation port so as to evacuate said process space to a first process pressure; and

a second pump connected to said second evacuation port so as to evacuate said process space to a second process pressure lower than said first process pressure,

wherein said second pump is disposed in the vicinity of said second end of said processing vessel.

51. A semiconductor device, comprising:

a silicon substrate; and

an insulation film formed on said silicon substrate with a thickness of 2-4 atomic layers.

52. The semiconductor device as claimed in claim 51, wherein said insulation film has a uniform thickness within the range of 2-4 atomic layers.

53. The semiconductor device as claimed in claim 51, wherein said insulation film comprises an oxide film.

54. The semiconductor device as claimed in claim 51, wherein said insulation film comprises a silicon oxynitride film.

55. The semiconductor device as claimed in claim 51, further comprising a high-K dielectric film formed on said insulation film and a gate electrode formed on said high-K dielectric film.

56. A semiconductor device, comprising:

a silicon substrate; and

an insulation film formed on said silicon substrate,

said insulation film is formed by nitriding an oxide film formed on said silicon substrate with a thickness of 1-4 atomic layers.

57. A method of processing a substrate, comprising the step of forming an oxide film on a silicon substrate surface by an oxidation processing using oxygen radicals with a partial pressure in the range of 133-133×

10<sup>−

4</sup> mPa.

58. The method as claimed in claim 57, wherein said oxidation processing is continued over the duration of about 5 minutes or less.

59. The method as claimed in claim 57, wherein said oxidation processing is conducted under existence of oxygen radicals excited by ultraviolet radiation having a wavelength of 172 nm, by setting a power of said ultraviolet radiation to the range of 5-50 mW/cm² right underneath a ultraviolet source and further by setting an oxygen partial pressure to the range of 133 mPa-133 Pa.

60. A method of fabricating a semiconductor device, comprising the steps of:

forming a base oxide film on a silicon substrate surface;

forming a high-K dielectric film on said base oxide film; and

forming a gate electrode layer on said high-K dielectric film,

wherein said step of forming said base oxide film includes a step of forming an oxide film on said silicon substrate surface by an oxidation processing while using oxygen radicals with a partial pressure of 133-133×

10<sup>−

4</sup> mPa.

61. The method as claimed in claim 60, wherein said oxidizing processing is continued over the duration of about 5 minutes or less.

62. The method as claimed in claim 60, wherein said oxidation processing is conducted under existence of oxygen radicals excited by ultraviolet radiation having the wavelength of 172 nm by setting the power of the ultraviolet radiation to the range of 5-50 mW/cm² right underneath the ultraviolet source and setting the oxygen partial pressure to the range of 133 mPa-133 Pa.

63. A method of processing a substrate, comprising the steps of:

supplying an NO gas to a silicon substrate surface; and

forming an oxynitride film on said silicon substrate surface by exciting said NO gas with ultraviolet radiation.

64. The method as claimed in claim 63, wherein said ultraviolet radiation has a wavelength of about 172 nm.

65. The method as claimed in claim 63, wherein said ultraviolet radiation is formed by a dielectric barrier discharge tube confined with xenon.

66. The method as claimed in claim 63, wherein said oxynitride film is formed with a thickness of about 0.5 nm.

67. The method as claimed in claim 63, wherein said step of forming said oxynitride film is conducted at a substrate temperature of about 450°

C.

68. The method as claimed in claim 63, wherein said step of forming said oxynitride film is continued over the duration of 200 seconds or less.

69. The method as claimed in claim 63, wherein said step of forming said oxynitride film is conducted under a process pressure in the range of 1.33-13.3×

10<sup>−

3</sup> Pa.

70. The method as claimed in claim 63, wherein said step of forming said NO gas is started before increasing a temperature of said silicon substrate.

71. The method as claimed in claim 63, further comprising, before the step of forming said oxynitride film, the step of removing a native oxide film from said silicon substrate surface.

72. A method of fabricating a semiconductor device, comprising the steps of:

forming an oxynitride film on a silicon substrate surface by supplying an NO gas to said silicon substrate surface and exciting said NO gas with ultraviolet radiation;

forming a high-K dielectric film on said oxynitride film; and

forming a gate electrode on said high-K dielectric film.

73. The method as claimed in claim 72, wherein said ultraviolet radiation has a wavelength of 172 nm.