Magnetoresistive device and method of producing the same

• US 20030008416A1
• Filed: 04/16/2002
• Published: 01/09/2003
• Est. Priority Date: 04/16/2001
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shimura, Ken-Ichi, Fukumoto, Yoshiyuki, Kamijo, Atsushi, Tsuge, Hisanao, Mitsuzuka, Tsutomu
• Granted Patent: US 6,914,257 B2
• Time in Patent Office: Days
• US Class Current: 438/3
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: H01F 41/307 insulating or semiconductive spacer
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

In accordance with a method of producing an MR (MagnetoResistive) device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on the first ferromagnetic layer and a second ferromagnetic layer formed on the insulation layer, a metal or a semiconductor is deposited on the first ferromagnetic layer. The metal or the semiconductor is then caused to react to oxygen of a ground level to become an oxide layer, which is the oxide of the metal or that of the semiconductor. Subsequently, the oxide layer is caused to react to oxygen of an excitation level to form the insulation layer. The second ferromagnetic layer is formed on the insulation layer.

Claims

1. A method of producing an MR (MagnetoResistive) device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal or a semiconductor on said first ferromagnetic layer;

causing the metal or the semiconductor to react to oxygen of a ground level to thereby form an oxide layer comprising an oxide of the metal or an oxide of the semiconductor;

causing said oxide layer to react to oxygen of an excitation level to thereby form said insulation layer; and

forming said second ferromagnetic layer on said insulation layer.

2. The method as claimed in claim 1, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

3. The method as claimed in claim 1, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

4. The method as claimed in claim 1, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

5. The method as claimed in claim 1, wherein oxygen of the excitation level is produced by dissociation of ozone.

6. The method as claimed in claim 1, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

7. The method as claimed in claim 1, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

8. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal or a semiconductor on said first ferromagnetic layer to thereby form a first metal or semiconductor layer;

causing said first metal or semiconductor layer to react to oxygen of a ground level to thereby form an oxide layer comprising an oxide of the metal or an oxide of the semiconductor;

depositing a metal or a semiconductor on said oxide layer to thereby form a second metal or semiconductor layer;

feeding oxygen of an excitation level to a surface of said second metal or semiconductor layer to thereby form said insulation layer; and

forming said second ferromagnetic layer on said insulation layer.

9. The method as claimed in claim 8, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

10. The method as claimed in claim 8, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

11. The method as claimed in claim 8, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

12. The method as claimed in claim 8, wherein oxygen of the excitation level is produced by dissociation of ozone.

13. The method as claimed in claim 8, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

14. The method as claimed in claim 8, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

16. The method as claimed in claim 15, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

17. The method as claimed in claim 15, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

18. The method as claimed in claim 15, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

19. The method as claimed in claim 15, wherein oxygen of the excitation level is produced by dissociation of ozone.

20. The method as claimed in claim 15, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

21. The method as claimed in claim 15, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

15. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing an oxide of a metal or an oxide of a semiconductor on said first ferromagnetic layer to thereby form an oxide layer;

causing said oxide layer to react to oxygen of an excitation level to thereby form said insulation layer; and

forming said second ferromagnetic layer on said insulation layer.

22. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing an oxide of a metal or an oxide of a semiconductor on said first ferromagnetic layer to thereby form a first oxide layer;

depositing a metal or a semiconductor on said first oxide layer to thereby form a metal or semiconductor layer;

feeding oxygen of an excitation level to a surface of said metal or semiconductor layer to thereby form said insulation layer; and

forming said second ferromagnetic layer on said insulation layer.

23. The method as claimed in claim 22, wherein the metal comprises at least one of aluminum, germanium;

yttrium and lanthanoids.

24. The method as claimed in claim 22, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

25. The method as claimed in claim 22, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

26. The method as claimed in claim 22, wherein oxygen of the excitation level is produced by dissociation of ozone.

27. The method as claimed in claim 22, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

28. The method as claimed in claim 22, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

30. The method as claimed in claim 29, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

31. The method as claimed in claim 29, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

32. The method as claimed in claim 29, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

33. The method as claimed in claim 29, wherein oxygen of the excitation level is produced by dissociation of ozone.

34. The method as claimed in claim 29, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

35. The method as claimed in claim 29, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

37. The method as claimed in claim 36, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

38. The method as claimed in claim 36, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

39. The method as claimed in claim 36, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

40. The method as claimed in claim 36, wherein oxygen of the excitation level is produced by dissociation of ozone.

41. The method as claimed in claim 36, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

42. The method as claimed in claim 36, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

29. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal or a semiconductor on said first ferromagnetic layer to thereby form a first metal or semiconductor layer;

causing said first metal or semiconductor layer to react to nitrogen of an excitation level to thereby form a nitride layer comprising a nitride of the metal or a nitride of the semiconductor;

depositing a metal or a semiconductor on said nitride layer to thereby form a second metal or semiconductor layer; and

causing said second metal or semiconductor layer to react to oxygen of a ground level or the excitation level to thereby transform said second metal or semiconductor layer to an oxide of the metal or an oxide of the semiconductor;

wherein said insulation layer comprises said nitride and said oxide, said nitride contacting said first ferromagnetic layer.

36. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

forming, by using a nitride of a metal or a nitride of a semiconductor as a material, a nitride layer comprising said nitride on said first ferromagnetic layer;

depositing a metal or a semiconductor on said nitride layer; and

causing the metal or the semiconductor deposited on said nitride layer to react to oxygen of a ground level or an excitation level to thereby transform said metal or said semiconductor to an oxide;

wherein said insulation layer comprises said nitride and said oxide, said nitride contacting said first ferromagnetic layer.

43. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal element or a semiconductor element on said first ferromagnetic layer in an excited nitrogen atmosphere to thereby form a nitride layer comprising a nitride of said metal element or a nitride of said semiconductor element;

depositing a metal or a semiconductor on said nitride layer to thereby form a metal or semiconductor layer; and

causing said metal or semiconductor layer to react to oxygen of a ground level or an excitation level to thereby transform said metal or semiconductor layer to an oxide;

wherein said insulation layer comprises said nitride and said oxide, said nitride contacting said first ferromagnetic layer.

44. The method as claimed in claim 43, wherein the metal comprises at least one of aluminum, germanium, yttrium and lanthanoids.

45. The method as claimed in claim 43, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and alloys thereof.

46. The method as claimed in claim 43, wherein oxygen of the excitation level is produced by exciting oxygen with a high frequency wave or a microwave.

47. The method as claimed in claim 43, wherein oxygen of the excitation level is produced by dissociation of ozone.

48. The method as claimed in claim 43, wherein oxygen of the excitation level is produced by radiating ultraviolet rays on oxygen.

49. The method as claimed in claim 43, wherein oxygen of the excitation level is produced by dissociation of dinitrogen oxide.

50. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal or a semiconductor on said first ferromagnetic layer to thereby form a metal or semiconductor layer;

causing said metal or semiconductor layer to react to nitrogen of an excitation level to thereby form a nitride layer comprising a nitride of the metal or a nitride of the semiconductor; and

forming, by using an oxide of a metal or an oxide of a semiconductor, an oxide layer comprising said oxide;

wherein said insulation layer comprises said nitride layer and said oxide layer, said nitride layer contacting said first ferromagnetic layer.

51. The method as claimed in claim 50, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

52. The method as claimed in claim 50, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

53. The method as claimed in claim 50, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

54. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

forming, by using a nitride of a metal or a nitride of a semiconductor as a material, a nitride layer comprising said nitride; and

forming, by using an oxide of a metal or an oxide of a semiconductor, an oxide layer comprising said oxide on said nitride layer;

wherein said insulation layer comprises said nitride layer sand said oxide layer, said nitride layer contacting said first ferromagnetic layer.

55. The method as claimed in claim 54, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

56. The method as claimed in claim 54, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

57. The method as claimed in claim 54, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

59. The method as claimed in claim 58, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

60. The method as claimed in claim 58, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

61. The method as claimed in claim 58, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

58. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal element or a semiconductor element on said first ferromagnetic layer in an excited nitrogen atmosphere to thereby form a nitride layer comprising a nitride of said metal element or a nitride of said semiconductor element; and

forming, by using an oxide of a metal or an oxide of a semiconductor as a material, an oxide layer comprising said oxide on said nitride layer;

wherein said insulation layer comprises said nitride layer and said oxide layer, said nitride layer contacting said first ferromagnetic layer.

62. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal or a semiconductor on said first ferromagnetic layer to thereby form a metal or semiconductor layer;

causing said metal or semiconductor layer to react to nitrogen of an excitation level to thereby form a nitride layer comprising a nitride of the metal or a nitride of the semiconductor; and

depositing a metal element or a semiconductor element on said nitride layer in an oxidizing atmosphere to thereby form an oxide of said metal element or an oxide of said semiconductor element;

wherein said insulation layer comprises said nitride and said oxide, said nitride contacting said first ferromagnetic layer.

63. The method as claimed in claim 62, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

64. The method as claimed in claim 62, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

65. The method as claimed in claim 62, wherein said first ferromagnetic layer comprises any one of, cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

66. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

forming, by using a nitride of a metal or a nitride of a semiconductor as a material, a nitride layer comprising said nitride on said first ferromagnetic layer; and

depositing a metal element or a semiconductor element on said nitride layer in an oxidizing atmosphere to thereby form an oxide of said metal element or an oxide of said semiconductor element;

wherein said insulation layer comprises said nitride and said oxide, said nitride layer contacting said first ferromagnetic layer.

67. The method as claimed in claim 66, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

68. The method as claimed in claim 66, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

69. The method as claimed in claim 66, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

70. A method of producing an MR device including a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation layer formed on said first ferromagnetic layer, and a second ferromagnetic layer formed on said insulation layer, said method comprising the steps of:

depositing a metal element or a semiconductor element on said first ferromagnetic layer in an excited nitrogen atmosphere to thereby form a nitride layer comprising a nitride of said metal element of a nitride of said semiconductor element; and

depositing a metal element or a semiconductor element on said nitride layer in an oxidizing atmosphere to thereby form an oxide of said metal element or an oxide of said semiconductor element;

wherein said insulation layer comprises said nitride and said oxide, said nitride contacting said first ferromagnetic layer.

71. The method as claimed in claim 70, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

72. The method as claimed in claim 70, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

73. The method as claimed in claim 70, wherein said first ferromagnetic layer comprises any one of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

74. An MR device comprising:

two ferromagnetic layers constituting a ferromagnetic tunnel junction and each comprising a ferromagnetic material; and

a tunnel barrier layer comprising a plurality of insulation layers, which include a layer of an oxide of a metal or an oxide of a semiconductor, and sandwiched between said two ferromagnetic layers;

wherein at least one of two insulation layers contacting said two ferromagnetic layers is formed of a substance less reactive to a substance constituting said ferromagnetic layers than said oxide.

75. The MR device as claimed in claim 74, wherein in said tunnel barrier layer at least one of said two insulation layers contacting said two ferromagnetic layers comprises a nitride of a metal or a nitride of a semiconductor.

76. The MR device as claimed in claim 75, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

77. The MR device as claimed in claim 74, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

78. The method as claimed in claim 74, wherein said ferromagnetic layers each comprise anyone of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

80. The MR device as claimed in claim 79, wherein in said tunnel barrier layer at least one of said two portions of said insulation layer comprises a nitride of a metal or a nitride of a semiconductor.

81. The MR device as claimed in claim 80, wherein the metal constituting said nitride comprises at least one of aluminum, germanium, yttrium and lanthanoids.

82. The MR device as claimed in claim 79, wherein the metal constituting said oxide comprises at least one of aluminum, germanium, yttrium and lanthanoids.

83. The method as claimed in claim 79, wherein said ferromagnetic layers each comprise anyone of cobalt, iron, nickel and an alloy containing at least one of cobalt, iron and nickel.

79. An MR device comprising:

two ferromagnetic layers constituting a ferromagnetic tunnel junction and each comprising a ferromagnetic material; and

a tunnel barrier layer comprising an insulation layer, which includes an oxide of a metal or an oxide of a semiconductor and has a graded composition, and sandwiched between said two ferromagnetic layers;

wherein at least one of two portions of said insulation layer contacting said two ferromagnetic layers is formed of a material less reactive to a substance constituting said insulation layer, which contacts said one portion, than said oxide.