Method for deposition of diamond-like carbon and silicon-doped diamond-like carbon coatings from a hall-current ion source

• US 6,086,962 A
• Filed: 02/03/1999
• Issued: 07/11/2000
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: Morgan Advanced Ceramics Inc.
• Original Assignee: Diamonex, Inc. (Morgan Advanced Materials PLC)
• Inventors: Petrmichl, Rudolph Hugo, Brown, David Ward, Mahoney, Leonard Joseph
• Primary Examiner(s): King, Roy V.
• Application Number:
  US09/243,913
• Time in Patent Office: 524 Days
• Field of Search: 427/577, 427/249.7, 427/902, 427/904, 427/523, 427/571
• US Class Current: 427/577
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: C23C 16/486 using ion beam radiation
• CPC Class Codes: G11B 5/8408 protecting the magnetic layer
• CPC Class Codes: Y10S 427/103 Diamond-like carbon coating, i.e. DLC
• CPC Class Codes: Y10S 427/104 Utilizing low energy electromagnetic radiation, e.g. microwave, radio wave, IR, UV, visible, actinic laser

Abstract

A unique Hall-Current ion source apparatus is used for direct ion beam deposition of DLC coatings with hardness values greater than 10 GPa and at deposition rates greater than 10 Å per second. This ion source has a unique fluid-cooled anode with a shadowed gap through which ion sources feed gases are introduced while depositing gases are injected into the plasma beam. The shadowed gap provides a well maintained, electrically active area at the anode surface which stays relatively free of non-conductive deposits. The anode discharge region is insulatively sealed to prevent discharges from migrating into the interior of the ion source. A method is described in which a substrate is disposed within a vacuum chamber, coated with a coating of DLC or Si-DLC at a high deposition rate using a Hall-Current ion source operating on carbon-containing or carbon-containing and silicon-containing precursor gases, respectively. The method is particularly advantageous for producing thin, hard, wear resistant DLC and Si-DLC coatings for magnetic transducers and media used for magnetic data storage applications.

Claims

1. A method of depositing a diamond-like carbon (DLC) coating onto the surface of a substrate using a Hall-Current ion source comprising the steps of:

(a) mounting said substrate in a deposition vacuum chamber containing said Hall-Current ion source and evacuating the air from said chamber;

(b) supplying an inert gas to at least one self-sustaining cathode electron source of said Hall-current ion source and exciting said cathode electron source to provide a supply of electrons to an anode of said Hall-Current ion source, said anode being electrically insulated from said vacuum chamber in such a manner to prohibit the formation of a plasma migrating into the interior of said Hall-Current ion source behind said anode;

(c) introducing plasma maintenance gases through a gap of said anode and into an anode discharge region within said vacuum chamber and applying a voltage to provide an anode discharge current to flow between said anode and said electron source, wherein a magnetic field established by electromagnetic means is formed across said anode discharge region and electrons ionize the plasma maintenance gases to form a plasma beam of gas ions throughout said anode discharge region;

(d) plasma ion beam depositing a layer of DLC from carbon-containing precursor gases using said plasma beam while thermally cooling said anode by cooling means other than by radiative thermal emission;

(e) increasing the vacuum chamber pressure to atmospheric pressure; and

(f) recovering a DLC-coated substrate product.

2. The method of claim 1 wherein said DLC layer is deposited at a rate greater than 5 Å

per second.

3. The method of claim 1 wherein said DLC layer is deposited at a rate greater than 10 Å

per second.

4. The method of claim 1 wherein said DLC layer is deposited at a rate greater than 10 Å

per second and with a Nanoindentation hardness greater than 10 GPa.

5. The method of claim 1 wherein the anode discharge current flowing between said anode and said cathode electron source at least partially drives said electromagnetic means.

6. The method of claim 1 including alternating current circuit means for at least partially driving said electromagnetic means and for periodically reversing the direction of the lines of flux of the magnetic field of said electromagnetic means.

7. The method of claim 1 wherein the direction of the lines of flux of the magnetic field established by said electromagnetic means are substantially parallel to the surface of said anode at the second end of said anode discharge region.

8. The method of claim 1 wherein the direction of the lines of flux of the magnetic field established by said electromagnetic means diverge in a direction substantially the same as that of the plasma beam exiting said anode discharge region.

9. The method of claim 1 wherein said plasma maintenance gases are inert gases selected from the group consisting of argon, neon, krypton, xenon and mixtures thereof.

10. The method of claim 1 wherein said cathode electron source is disposed axisymmetrically with respect to said anode discharge region.

11. The method of claim 1 wherein said cooling means comprises an injector for directly contacting said anode with a cooling fluid.

12. The method of claim 1 wherein the plasma maintenance gases are substantially uniformly distributed through said gap in the anode from an injection means and into said anode discharge region and the resulting anode discharge current is substantially uniformly distributed adjacent to said gap.

13. The method of claim 1 for depositing materials onto substrates wherein the dimensions of the gap within said anode being at least greater than the characteristic Debye length of the local plasma formed near the gap in said anode and the shape of the gap being configured so as to substantially restrict line-of-sight deposition of coating onto said anode within said gap such that said anode discharge current is substantially maintained at said anode within the gap near a localized region of the plasma maintenance gases passing into said anode discharge region.

14. The method of claim 1 wherein a power supply is used to provide between about 500 to about 1000 volts to said electron source.

15. The method of claim 1 wherein said carbon-containing precursor gases are selected from the group consisting of methane, ethane, ethylene, butane, butadiene, acetylene, hexane, cyclohexane, and mixtures thereof.

16. The method of claim 15 wherein carbon-containing precursor gases also include an inert gas selected from the group consisting of helium, argon, neon, krypton, xenon and mixtures thereof.

17. The method of claim 16 wherein carbon-containing precursor gases also include a reactive gas selected from the group consisting of hydrogen, nitrogen, nitrogen-containing compounds, fluorine-containing compound and mixtures thereof.

18. The method of claim 2 wherein said DLC layer is deposited at a rate in the range of about 5 to about 200 Å

per second and with a Nanoindentation hardness in the range of about 10 GPa to about 40 GPa.

19. The method of claim 1 wherein said substrate is selected from the group consisting of metals, semiconductors, ceramics, glasses, polymers, and mixtures thereof.

20. The method of claim 12 wherein a distributor means is included in said housing for introducing said precursor gases directly into the plasma beam and separately from that of said injection means for introducing plasma maintenance gases through said gap.

21. The method of claim 20 wherein said distributor means comprises at least one tube having a nozzle at one end for directing the precursor gases into said anode discharge region.

22. The method of claim 20 wherein said distributor means comprises at least one distributor ring for directing the deposition gas into said anode discharge region.

23. The method of claim 20 wherein said distributor means comprises at least one tube having a nozzle at one end for directing the precursor gases outside said anode discharge region.

24. The method of claim 20 wherein said distributor means comprises at least one distributor ring for directing the precursor gases outside said anode discharge region.

25. The method of claim 1 wherein the flow of said carbon-containing precursor gases is pulsed during the plasma ion beam deposition and said plasma maintenance gas continuously introduced through said gap.

26. The method of claim 1 wherein said carbon-containing precursor gases are continuously introduced during the plasma ion beam deposition and said anode discharge current is pulsed.

27. The method of claim 1 wherein said substrate contains data recording media.

28. The method of claim 1 wherein said substrate is a magnetic transducer used with magnetic recording media.

29. The method of claim 1 wherein said substrate is mounted in said deposition vacuum chamber so that both sides of the substrate are simultaneously coated with a layer of DLC.

30. The method of claim 1 wherein voltage is applied to said anode and to said electromagnetic means by separate DC power supplies.

31. A method of depositing a silicon-doped diamond-like carbon (Si-DLC) coating onto the surface of a substrate using a Hall-Current ion source comprising the steps of:

(a) mounting said substrate in a deposition vacuum chamber containing said Hall-Current ion source and evacuating the air from said chamber;

(b) supplying an inert gas to a self-sustaining cathode electron source of said Hall-current ion source and exciting said cathode electron source to provide a supply of electrons to an anode of said Hall-Current ion source, said anode being electrically insulated from said vacuum chamber in such a manner to prohibit the formation of a plasma migrating into the interior of said Hall-Current ion source behind said anode;

(c) introducing plasma maintenance gases through a gap of said anode and into an anode discharge region within said vacuum chamber and applying a voltage to provide an anode discharge current to flow between said anode and said electron source, wherein a magnetic field established by electromagnetic means is formed across said anode discharge region and electrons ionize the plasma maintenance gases to form a plasma beam of gas ions throughout said anode discharge region;

(d) plasma ion beam depositing a layer of Si-DLC from carbon-containing and silicon-containing precursor gases using said plasma beam while thermally cooling said anode by cooling means other than by radiative thermal emission;

(e) increasing the vacuum chamber pressure to atmospheric pressure; and

(f) recovering a Si-DLC-coated substrate product.

32. The method of claim 31 wherein said carbon-containing and silicon-containing precursor gases are selected from the group consisting silane, disilane, methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane (TMS), diethylsilane, and mixtures thereof.

33. The method of claim 31 wherein said Si-DLC coating is deposited at a rate greater than 5 Å

per second and with a Nanoindentation hardness greater than 10 GPa.

34. The method of claim 31 wherein the anode discharge current flowing between said anode and said cathode electron source at least partially drives said electromagnetic means.

35. The method of claim 31 including alternating current circuit means for at least partially driving said electromagnetic means and for periodically reversing the direction of the lines of flux of the magnetic field of said electromagnetic means.

36. The method of claim 31 wherein the direction of the lines of flux of the magnetic field established by said electromagnetic means are substantially parallel to the surface of said anode at the second end of said anode discharge region.

37. The method of claim 31 wherein the direction of the lines of flux of the magnetic field established by said electromagnetic means diverge in a direction substantially the same as that of the plasma beam exiting said anode discharge region.

38. The method of claim 31 wherein said plasma maintenance gases are inert gases selected from the group consisting of argon, neon krypton, xenon and mixtures thereof.

39. The method of claim 31 wherein said cathode electron source is disposed axisymmetrically with respect to said anode discharge region.

40. The method of claim 31 wherein said cooling means comprises an injector for directly contacting said anode with a cooling fluid.

41. The method of claim 31 wherein the plasma maintenance gases are substantially uniformly distributed through said gap in the anode from an injection means and into said anode discharge region and the resulting anode discharge current is substantially uniformly distributed adjacent to said gap.

42. The method of claim 31 for depositing materials onto substrates wherein the dimensions of the gap within said anode being at least greater than the characteristic Debye length of the local plasma formed near the gap in said anode and the shape of the gap being configured so as to substantially restrict line-of-sight deposition of coating onto said anode within said gap such that said anode discharge current is substantially maintained at said anode within the gap near a localized region of the plasma maintenance gases passing into said anode discharge region.

43. The method of claim 31 wherein a power supply is used to provide between about 500 to about 1000 volts to said electron source.

44. The method of claim 32 wherein said precursor gases also include an inert gas selected from the group consisting of helium, argon, neon, krypton, xenon and mixtures thereof.

45. The method of claim 32 wherein said precursor gases also include a reactive gas selected from the group consisting of hydrogen, nitrogen, nitrogen-containing compounds, fluorine-containing compound and mixtures thereof.

46. The method of claim 31 wherein said Si-DLC layer is deposited at a rate in the range of about 10 to about 200 Å

per second and with a Nanoindentation hardness in the range of about 10 GPa to about 40 GPa.

47. The method of claim 31 wherein said substrate is selected from the group consisting of metals, semiconductors, ceramics, glasses, polymers, and mixtures thereof.

48. The method of claim 31 wherein a distributor means is included in said housing for introducing said precursor gases directly into the plasma beam and separately from that of said injection means for introducing plasma maintenance gases through the gap.

49. The method of claim 48 wherein said distributor means comprises at least one tube having a nozzle at one end for directing the precursor gases into said anode discharge region.

50. The method of claim 48 wherein said distributor means comprises at least one distributor ring for directing the deposition gas into said anode discharge region.

51. The method of claim 48 wherein said distributor means comprises at least one tube having a nozzle at one end for directing the precursor gases outside said anode discharge region.

52. The method of claim 48 wherein said distributor means comprises at least one distributor ring for directing the precursor gases outside said anode discharge region.

53. The method of claim 31 wherein the flow of said silicon-containing precursor gases is pulsed during the plasma ion beam deposition and said plasma maintenance gas continuously introduced through said gap.

54. The method of claim 31 wherein said silicon-containing precursor gases are continuously introduced during the plasma ion beam deposition and said anode discharge current is pulsed.

55. The method of claim 31 wherein said substrate contains data recording media.

56. The method of claim 31 wherein said substrate is a magnetic transducer used with magnetic recording media.

57. The method of claim 31 wherein said substrate is mounted in said deposition vacuum chamber so that both sides of the substrate are simultaneously coated with a layer of Si-DLC.

58. The method of claim 31 wherein voltage is applied to said anode and to said electromagnetic means by separate DC power supplies.