Method of fabricating group-III nitride semiconductor crystal, method of fabricating gallium nitride-based compound semiconductor, gallium nitride-based compound semiconductor, gallium nitride-based compound semiconductor light-emitting device, and light source using the semiconductor light-emitting device

• US 20020155712A1
• Filed: 04/17/2002
• Published: 10/24/2002
• Est. Priority Date: 08/18/2000
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Showa Denko KK
• Inventors: Urashima, Yasuhito, Sakurai, Tetsuo, Miki, Hisayuki, Okuyama, Mineo
• Granted Patent: US 6,852,161 B2
• Time in Patent Office: Days
• US Class Current: 438/689
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02661 In-situ cleaning
• CPC Class Codes: H01L 33/0075 comprising nitride compounds

Abstract

A method of fabricating a film of group-III nitride semiconductor crystal includes a step of using metal material to deposit particles of a group III metal on a substrate surface in an atmosphere containing no nitrogen source, a step of nitriding the particles in an atmosphere containing a nitrogen source and no metal material, and a step of growing group-III nitride semiconductor crystal on the substrate surface on which the particles have been deposited.

Claims

1. A method of fabricating a group-III nitride semiconductor crystal comprising:

a first step of depositing particles of a group III metal on a substrate surface;

a second step of nitriding the particles in an atmosphere containing a nitrogen source; and

a third step of using a vapor phase growth method to grow a group-III nitride semiconductor crystal represented by In_xGa_yAl_zN, where x+y+z=1, 0≦

x≦

1, 0≦

y≦

1, and 0≦

z≦

1, on the substrate surface on which the particles have been deposited.

2. The method according to claim 1, wherein the substrate is a sapphire (A1₂O₃) substrate.

3. The method according to claim 1, wherein the group III metal is In_uGa_vAl_w, where u+v+w=1, 0≦

u≦

1, 0≦

v≦

1, and 0≦

w≦

1.

4. The method according to claim 1, wherein the group III metal particles are deposited by thermal decomposition of metallo-organic material.

5. The method according to claim 1, wherein the first step is performed in an atmosphere containing no nitrogen source.

6. The method according to claim 1 or claim 5, wherein the first step is performed at or above a melting point of the group III metal.

7. The method according to claim 1, wherein the second step is performed in an atmosphere containing no metal material.

8. The method according to claim 1 or claim 7, wherein the second step is performed at or above a temperature used in the first step.

9. The method according to claim 1, wherein the third step is performed at or above a temperature used in the second step.

10. The method according to claim 1, wherein the vapor phase growth method is a metallo-organic chemical vapor deposition method.

11. The method according to claim 1, wherein the group III metal particles nitrided in the second step are polycrystalline and/or noncrystalline group-III nitrides and include unreacted metal.

12. The method according to claim 1, further comprising a step of forming a mask layer on the substrate to grow a gallium nitride-based compound semiconductor crystal at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystal.

13. The method according to claim 12, wherein the mask layer formed on the substrate comprises a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is low and a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is high.

14. The method according to claim 12, wherein the step of forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystal.

15. The method according to claim 12, wherein the mask layer is formed by flowing a Si-containing material gas over the substrate.

16. The method according to claim 12, wherein the mask layer is formed by simultaneously flowing a Si-containing material gas and ammonia over the substrate.

17. The method according to claim 12, wherein the mask layer formed includes a portion that covers the substrate and a portion that exposes the substrate.

18. The method according to claim 12, wherein the mask layer is formed by simultaneously flowing a group-III-element-containing material gas and a Si-containing material gas over the substrate.

20. The method according to claim 19, wherein the sapphire substrate has a (0001) plane having a vertical axis inclined from <

0001>

in a specific direction.

21. The method according to claim 20, wherein the specific direction is <

1-100> and

an angle of inclination from <

0001>

is from 0.2°

to 15°

.

22. The method according to claim 19, wherein the temperature T1 is not lower than 900°

C. and the temperature T3 is not lower than 1000°

C.

23. The method according to claim 19, wherein, the thermal decomposition of metallo-organic material in the first step takes place in a hydrogen atmosphere.

24. The method according to claim 19, wherein the metal is deposited on the sapphire substrate not as a layer but as particles.

25. The method according to claim 24, wherein the metal particles has a height of not less than 50 Å

and not more than 1000 Å

from the sapphire substrate surface to an apex of the metal particles.

26. The method according to claim 19, wherein the metal nitrided in the second step is comprised of polycrystals which are in a region of In_uGa_vAl_wN_k, where u+v+w=1, 0≦

u, v, w≦

1 and 0<

k<

1, in which a stoichiometric ratio between the nitrogen and the metal is not 1;

1.

27. The method according to claim 19, further comprising a step of forming a mask layer on the substrate to grow a gallium nitride-based compound semiconductor crystal at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystal.

28. The method according to claim 27, wherein the mask layer formed on the substrate comprises a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is low and a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is high.

29. The method according to claim 27, wherein the step of forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystal.

30. The method according to claim 27, wherein the mask layer is formed by flowing a Si-containing material gas over the substrate.

31. The method according to claim 27, wherein the mask layer is formed by simultaneously flowing a Si-containing material gas and ammonia over the substrate.

32. The method according to claim 27, wherein the mask layer formed comprises a portion that covers the substrate and a portion that exposes the sapphire substrate.

33. The method according to claim 27, wherein the mask layer is formed by simultaneously flowing a group-III-element-containing material gas and a Si-containing material gas over the substrate.

35. The method according to claim 34, wherein the group-III nitride semiconductor crystal grown on the substrate has a surface with a (0001) plane having a vertical axis inclined from <

0001>

in a specific direction.

36. The method according to claim 35, wherein the specific direction is <

11-20> and

an angle of inclination from <

0001>

is from 0.2°

to 15°

.

37. The method according to claim 34, further comprising a step of forming a mask layer on the substrate to grow a gallium nitride-based compound semiconductor crystal at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystal.

38. The method according to claim 37, wherein the mask layer formed on the substrate comprises a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is low and a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is high.

39. The method according to claim 37, wherein the step of forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystal.

40. The method according to claim 37, wherein the mask layer is formed by flowing a Si-containing material gas over the substrate.

41. The method according to claim 37, wherein the mask layer is formed by simultaneously flowing a Si-containing material gas and ammonia over the substrate.

42. The method according to claim 37, wherein the mask layer formed comprises a portion that covers the substrate and a portion that exposes the substrate.

43. The method according to claim 37, wherein the mask layer is formed by simultaneously flowing a group-III-element-containing material gas and a Si-containing material gas over the substrate.

85. A group-III nitride semiconductor fabricated by the method of fabricating the group III gallium nitride-based compound semiconductor crystal according to any one of claim 1, 19 and 34.

87. A gallium nitride-based compound semiconductor light-emitting device fabricated using the group III gallium nitride-based compound semiconductor according to claim 85 or the gallium nitride-based compound semiconductor according to claim 86.

88. A light source fabricated using the gallium nitride-based compound semiconductor light-emitting device according to claim 87.

19. A method of fabricating a group-III nitride semiconductor crystal comprising:

a first step of, in an atmosphere containing no nitrogen source, using thermal decomposition of metallo-organic material that includes at least one metal element selected from among In, Ga and Al to deposit on a sapphire substrate a metal represented by In_uGa_vAl_w, where u+v+w=1, 0≦

u≦

1, 0≦

v≦

1 and 0≦

w≦

1, at a temperature T1 that is not lower than a melting point of said metal;

a second step of nitriding the deposited metal at a temperature T2, where T2≧

T1, in an atmosphere containing a nitrogen source and no metallo-organic material; and

a third step of using a metallo-organic chemical vapor deposition method to epitaxially grow on the sapphire substrate on which the metal has been deposited, at a temperature T3, where T3≧

T2, a group-III nitride semiconductor crystal represented by In_xGa_yAl_zN, where x+y+z=1, 0≦

x≦

1, 0≦

y≦

1 and 0≦

z≦

1.

34. A method of fabricating a group-III nitride semiconductor crystal represented by In_xGa_yAl_zN, where x+y+z=1, 0≦

x≦

1, 0≦

y≦

1 and 0≦

z≦

1, comprising;

a first step of supplying group III metal material to a substrate to deposit the group III metal material and/or decomposition products thereof on the substrate;

a second step of heat-treating the substrate in an atmosphere containing a nitrogen source; and

a third step of using the group III metal material and nitrogen source to grow a group-III nitride semiconductor crystal on the substrate by a vapor phase method.

44. A method of fabricating a gallium nitride-based compound semiconductor, comprising:

a first step of adhering metal nuclei to a substrate;

a second step of annealing the metal nuclei;

a third step of nitriding the annealed metal nuclei to form growth nuclei; and

a fourth step of growing a gallium nitride-based compound on the substrate having the growth nuclei to form and grow a layer of gallium nitride-based compound semiconductor crystal.

45. The method according to claim 44, wherein the substrate is a sapphire substrate.

46. The method according to claim 44, wherein, in the first step, the metal nuclei are adhered to the substrate by flowing a source gas containing vapor of metallo-organic material and no nitrogen source.

47. The method according to claim 46, wherein the metallo-organic material comprises at least one member selected from among a metallo-organic material that contains gallium, a metallo-organic material that contains aluminum and a metallo-organic material that contains indium.

48. The method according to claim 44, wherein, in the second step, the metal nuclei are annealed by flowing just carrier gas containing neither a nitrogen source nor metallo-organic material vapor.

49. The method according to claim 44, wherein, in the third step, the metal nuclei are nitrided by flowing gas containing a nitrogen source and no metallo-organic material vapor.

50. The method according to claim 44, wherein, in the fourth step, the gallium nitride-based compound semiconductor crystal is grown by a metallo-organic chemical vapor deposition method by flowing gas containing both a nitrogen source and vapor of metallo-organic material.

51. The method according to claim 44 or claim 48, wherein the second step is performed at a temperature not lower than a temperature at which the first step is performed.

52. The method according to claim 44 or claim 49, wherein the third step is performed at a temperature not lower than a temperature at which the second step is performed.

53. The method according to claim 44 or claim 50, whrerin the fourth step is performed at a temperature not lower than a temperature at which the third step is performed.

54. The method according to claim 44, wherein the third step is performed after alternating the first and second steps two or more times.

55. The method according to claim 44, wherein the fourth step is performed after repeating the first, second and third steps two or more times.

56. The method according to claim 44, wherein the first step comprises two steps, which are a first-stage step of flowing a gas containing vapor of at least one member selected from among metallo-organic material containing aluminum, metallo-organic material containing gallium and metallo-organic material containing indium, and a second-stage step of flowing a gas containing vapor of a different metallo-organic material from that of the first-stage step.

57. The method according to claim 56, wherein the second step is performed after alternating the first-stage and second-stage steps of the first step two or more times.

58. The method according to claim 44, wherein the growth nuclei are substantially trapezoidal nitride semiconductor crystals having a flat apex that is parallel to the substrate and flat sides.

59. The method according to claim 44, further comprising a step of growing a separate layer of gallium nitride-based compound semiconductor crystal on the gallium nitride-based compound semiconductor crystal layer formed in the fourth step.

60. The method according to claim 44, further comprising a step of forming a mask layer on the substrate to grow a gallium nitride-based compound semiconductor crystal at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystal.

61. The method according to claim 60, wherein the mask layer formed on the substrate comprises a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is low and a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is high.

62. The method according to claim 60, wherein the step of forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystal.

63. The method according to claim 60, wherein the mask layer is formed by flowing a Si-containing material gas over the substrate.

64. The method according to claim 60, wherein the mask layer is formed by simultaneously flowing a Si-containing material gas and ammonia over the substrate.

65. The method according to claim 60, wherein the mask layer formed comprises a portion that covers the substrate and a portion that exposes the substrate.

66. The method according to claim 60, wherein the mask layer is formed by simultaneously flowing a group-III-element-containing material gas and a Si-containing material gas over the substrate.

68. The method according to claim 67, wherein the substrate is a sapphire substrate.

69. The method according to claim 67, wherein the second step is performed after alternating the first-stage and second-stage steps of the first step two or more times.

70. The method according to claim 67, wherein the third step is performed after alternating the first and second steps two or more times.

71. The method according to claim 67, wherein, in the first step, the metal nuclei are adhered to the substrate by flowing a gas containing metallo-organic material vapor and no nitrogen source.

72. The method according to claim 67, wherein, in the second step, the metal nuclei are nitrided by flowing gas containing a nitrogen source and no metallo-organic material vapor.

73. The method according to claim 67, wherein, in the third step, the gallium nitride-based compound semiconductor crystal is grown by a metallo-organic chemical vapor deposition method by flowing gas containing both a nitrogen source and vapor of metallo-organic material.

74. The method according to claim 67 or claim 72, wherein the second step is performed at a temperature not lower than a temperature at which the first step is performed.

75. The method according to claim 67 or 73, wherein the third step is performed at a temperature not lower than a temperature at which the second step is performed.

76. The method according to claim 67, wherein the growth nuclei are substantially trapezoidal group-III nitride semiconductor crystals having a flat apex that is parallel to the substrate and flat sides.

77. The method according to claim 67 further comprising a fourth step of growing a separate layer of gallium nitride-based compound semiconductor crystal on the gallium nitride-based compound semiconductor crystal layer formed in the third step.

78. The method according to claim 67 further comprising a fifth step of forming a mask layer on the substrate to grow a gallium nitride-based compound semiconductor crystal layer at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystal layer.

79. The method according to claim 78, wherein the mask layer formed on the substrate comprises a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is low and a portion comprised of material on which gallium nitride-based compound semiconductor growth rate is high.

80. The method according to claim 78, wherein the step of forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystal.

81. The method according to claim 78, wherein the mask layer is formed by flowing a Si-containing material gas over the substrate.

82. The method according to claim 78, wherein the mask layer is formed by simultaneously flowing a Si-containing material gas and ammonia over the substrate.

83. The method according to claim 78, wherein the mask layer formed comprises a portion that covers the substrate and a portion that exposes the substrate.

84. The method according to claim 78, wherein the mask layer is formed by simultaneously flowing a group-III-element-containing material gas and a Si-containing material gas over the substrate.

86. A gallium nitride-based compound semiconductor fabricated by the method of fabricating the gallium nitride-based compound semiconductor according to claim 44 or claim 67.

67. A method of fabricating a gallium nitride-based compound semiconductor comprising:

a first step of adhering metal nuclei to a substrate in which the first step comprises two steps, which are a first-stage step of flowing a gas containing vapor of at least one member selected from among metallo-organic material containing aluminum, metallo-organic material containing gallium and metallo-organic material containing indium, and a second-stage step of flowing gas containing vapor of a different metallo-organic material from that of the first-stage step;

a second step of nitriding the metal nuclei to form growth nuclei; and

a third step of growing a gallium nitride-based compound on the substrate having the growth nuclei to form and grow a layer of gallium nitride-based compound semiconductor crystal.