High performance magnetic tunnel barriers with amorphous materials

• US 7,270,896 B2
• Filed: 07/02/2004
• Issued: 09/18/2007
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Parkin, Stuart Stephen Papworth
• Primary Examiner(s): Bernatz; Kevin M.
• Application Number:
  US10/884,831
• Publication Number:
  US 20060003185A1
• Time in Patent Office: 1,173 Days
• Field of Search: None
• US Class Current: 428/811.1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• 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: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3295 Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers
• 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
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1121 Multilayer
• CPC Class Codes: Y10T 428/115 Magnetic layer composition
• CPC Class Codes: Y10T 428/1193 with interlaminar component [e.g., adhesion layer, etc.]
• CPC Class Codes: Y10T 428/32 Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer

Abstract

A magnetic tunneling element is constructed from a MgO or Mg—ZnO tunnel barrier and an amorphous magnetic layer in proximity with the tunnel baffler. The amorphous magnetic layer includes Co and at least one additional element selected to make the layer amorphous. Magnetic tunnel junctions formed from the amorphous magnetic layer, the tunnel barrier, and an additional ferromagnetic layer have tunneling magnetoresistance values of up to 200% or more.

Claims

1. A structure, comprising:

at least one tunnel barrier selected from the group of tunnel barriers consisting of MgO and Mg—

ZnO, wherein the tunnel barrier is crystalline and oriented in the (100) direction;

an amorphous magnetic layer that includes Co and at least one additional element selected to make the layer amorphous, wherein the amorphous layer is in proximity with the tunnel barrier, thereby permitting spin-polarized current to pass between the tunnel barrier and the magnetic layer; and

a ferromagnetic layer in proximity with the tunnel barrier,

wherein the ferromagnetic layer, the amorphous magnetic layer, and the tunnel barrier form a magnetic tunnel junction, and

wherein the structure is sufficiently well textured, the structure is sufficiently free of defects, and the amount of any oxide separating the tunnel barrier from the magnetic layers is sufficiently low, that the magnetic tunnel junction has a tunnel magnetoresistance (TMR) of greater than 100% at room temperature.

2. The structure of claim 1, wherein the amorphous layer includes an alloy of Co and Fe.

3. The structure of claim 1, comprising a crystalline layer sandwiched between the amorphous layer and the tunnel barrier.

4. The structure of claim 3, wherein the crystalline layer includes an alloy of Co and Fe.

5. The structure of claim 3, wherein the crystalline layer is in direct contact with both the amorphous layer and the tunnel barrier.

6. The structure of claim 1, wherein said at least one additional element comprises at least 10 atomic % of the amorphous layer.

7. The structure of claim 1, wherein said at least one additional element includes B.

8. The structure of claim 1, wherein said at least one additional element includes Zr.

9. The structure of claim 1, wherein said at least one additional element includes Hf.

10. The structure of claim 1, wherein the amorphous layer has a thickness in the range of 15 to 200 angstroms.

11. The structure of claim 1, wherein the magnetic tunnel junction has been annealed at a temperature greater than 300°

C.

12. The structure of claim 1, wherein the tunnel junction has a TMR of greater than 120% at room temperature.

13. The structure of claim 1, wherein the tunnel junction has a TMR of greater than 130% at room temperature.

14. The structure of claim 1, wherein the tunnel junction has a TMR of greater than 160% at room temperature.

15. The structure of claim 1, wherein the tunnel junction has a TMR of greater than 200% at room temperature.

16. The structure of claim 1, wherein the ferromagnetic layer has a body-centered cubic (bcc) structure.

17. The structure of claim 1, wherein the tunnel barrier comprises a MgO tunnel barrier.

18. The structure of claim 1, wherein the tunnel barrier comprises a Mg—

ZnO tunnel barrier.

19. The structure of claim 1, wherein the ferromagnetic layer comprises:

a first body centered cubic (bcc) magnetic layer and a second bcc magnetic layer; and

at least one spacer layer of bcc material between the bcc magnetic layers, wherein the spacer layer exchange couples the first and second bcc magnetic layers.

39. The structure of claim 1, wherein the tunnel barrier includes polycrystalline grains.

20. A structure, comprising:

at least one crystalline tunnel barrier selected from the group of tunnel barriers consisting of MgO and Mg—

ZnO;

an amorphous magnetic layer that includes Co and at least one additional element selected to make the layer amorphous, wherein the amorphous layer is in proximity with the tunnel barrier;

a crystalline layer between the amorphous layer and the tunnel barrier; and

an additional layer of magnetic material selected from the group consisting of ferromagnetic materials and ferrimagnetic materials, wherein the tunnel barrier, the amorphous layer, the crystalline layer, and the additional magnetic layer are configured to form a magnetic tunnel junction having a tunneling magnetoresistance (TMR) of at least 100%.

21. The structure of claim 20, wherein said at least one additional element comprises at least 10 atomic % of the amorphous layer.

22. The structure of claim 20, wherein said at least one additional element includes B.

23. The structure of claim 20, wherein said at least one additional element includes Zr.

24. The structure of claim 20, wherein said at least one additional element includes Hf.

25. The structure of claim 20, wherein the amorphous layer has a thickness in the range of 15 to 200 angstroms.

26. The structure of claim 20, wherein the amorphous layer includes an alloy of Co and Fe.

27. The structure of claim 20, wherein the tunnel barrier is oriented in the (100) direction.

28. The structure of claim 20, wherein the tunnel junction has a TMR of greater than 130% at room temperature.

29. The structure of claim 20, wherein the tunnel junction has a TMR of greater than 160% at room temperature.

30. The structure of claim 20, wherein the tunnel junction has a TMR of greater than 200% at room temperature.

31. The structure of claim 20, wherein the additional magnetic layer has a body-centered cubic (bcc) structure.

32. The structure of claim 20, wherein the tunnel barrier includes a Mg—

ZnO tunnel barrier.

33. The structure of claim 20, wherein the tunnel barrier includes a MgO tunnel barrier.

34. The structure of claim 20, wherein:

the tunnel barrier comprises a MgO tunnel barrier;

the amorphous layer and the crystalline layer each include an alloy of Co and Fe;

the additional magnetic layer has a body-centered cubic (bcc) structure; and

the tunnel barrier has a simple cubic structure and is oriented in the (100) direction.

35. The structure of claim 34, wherein the additional magnetic layer is oriented in the (100) direction.

36. The structure of claim 20, wherein the additional magnetic layer comprises:

a first body centered cubic (bcc) magnetic layer and a second bcc magnetic layer, wherein the first and second magnetic layers include material selected from the group consisting of ferromagnetic materials and ferrimagnetic materials; and

at least one spacer layer of bcc material between the bcc magnetic layers, wherein the spacer layer exchange couples the first and second bee magnetic layers.

37. The structure of claim 36, wherein said at least one spacer layer includes Cr.

38. The structure of claim 37, wherein said at least one spacer layer includes Mo.

40. The structure of claim 20, wherein the tunnel barrier includes polycrystalline grains.

41. The structure of claim 40, wherein the tunnel barrier is oriented in the (100) direction.

42. A structure, comprising:

at least one crystalline tunnel barrier selected from the group of tunnel barriers consisting of MgO and Mg—

ZnO;

an amorphous magnetic layer that includes Co and at least one additional element selected to make the layer amorphous;

an additional layer of magnetic material selected from the group consisting of ferromagnetic materials and ferrimagnetic materials, wherein;

the tunnel barrier, the amorphous layer, and the additional magnetic layer form a magnetic tunnel junction, and

the structure is sufficiently well textured, the structure is sufficiently free of defects, and the amount of any oxide separating the tunnel barrier from the magnetic layers is sufficiently low, that the magnetic tunnel junction has a tunnel magnetoresistance (TMR) of greater than 100% at room temperature.

43. The structure of claim 42, comprising a crystalline layer sandwiched between the amorphous layer and the tunnel barrier.

44. The structure of claim 43, wherein the crystalline layer includes an alloy of Co and Fe.

45. The structure of claim 44, wherein the crystalline layer is in direct contact with both the amorphous layer and the tunnel barrier.

46. The structure of claim 42, wherein the magnetic tunnel junction has been annealed at a temperature greater than 300°

C.

47. The structure of claim 42, wherein the additional magnetic layer has a body-centered cubic (bcc) structure.

48. The structure of claim 42, wherein the tunnel barrier comprises a MgO tunnel barrier.

49. The structure of claim 42, wherein the tunnel baffler comprises a Mg—

ZnO tunnel barrier.

50. The structure of claim 42, wherein the additional magnetic layer comprises:

a first body centered cubic (bcc) magnetic layer and a second bcc magnetic layer, wherein the first and second magnetic layers include material selected from the group consisting of ferromagnetic materials and ferrimagnetic materials; and

at least one spacer layer of bcc material between the bcc magnetic layers, wherein the spacer layer exchange couples the first and second bcc magnetic layers.

51. The structure of claim 42, wherein said at least one additional element comprises at least 10 atomic % of the amorphous layer.

52. The structure of claim 42, wherein said at least one additional element includes B.

53. The structure of claim 42, wherein said at least one additional element includes Zr.

54. The structure of claim 42, wherein said at least one additional element includes Hf.

55. The structure of claim 42, wherein the amorphous layer has a thickness in the range of 15 to 200 angstroms.

56. The structure of claim 42, wherein the amorphous layer includes an alloy of Co and Fe.

57. The structure of claim 42, wherein the tunnel barrier is oriented in the (100) direction.

58. The structure of claim 42, wherein the tunnel junction has a TMR of greater than 160% at room temperature.

59. The structure of claim 42, wherein the tunnel junction has a TMR of greater than 200% at room temperature.

60. The structure of claim 42, wherein:

the tunnel baffler comprises a MgO tunnel barrier;

the amorphous layer and the crystalline layer each include an alloy of Co and Fe;

the additional magnetic layer has a body-centered cubic (bcc) structure; and

the tunnel barrier has a simple cubic structure and is oriented in the (100) direction.

61. The structure of claim 50, wherein the additional magnetic layer is oriented in the (100) direction.

62. The structure of claim 50, wherein said at least one spacer layer includes Cr.

63. The structure of claim 50, wherein said at least one spacer layer includes Mo.

64. The structure of claim 42, wherein the tunnel barrier includes polycrystalline grains.

65. The structure of claim 64, wherein the tunnel baffler is oriented in the (100) direction.

66. A structure, comprising:

at least one crystalline tunnel barrier selected from the group of tunnel barriers consisting of MgO and Mg—

ZnO;

an amorphous magnetic layer that includes Co and at least one additional element selected to make the layer amorphous, wherein the amorphous layer is in proximity with the tunnel barrier, thereby permitting spin-polarized current to pass between the tunnel barrier and the magnetic layer; and

a layer of ferromagnetic material, wherein;

the tunnel barrier, the amorphous layer, and the ferromagnetic layer form a magnetic tunnel junction, and

the structure is sufficiently well textured, the structure is sufficiently free of defects, and the amount of any oxide separating the tunnel barrier from the magnetic layers is sufficiently low, that the magnetic tunnel junction has a tunnel magnetoresistance (TMR) of greater than 100% at room temperature.

67. The structure of claim 66, wherein the structure is sufficiently well textured, the structure is sufficiently free of defects, and the amount of any oxide separating the tunnel barrier from the magnetic layers is sufficiently low, that the magnetic tunnel junction has a tunnel magnetoresistance of greater than 130% at room temperature.

68. The structure of claim 66, wherein the tunnel barrier comprises a MgO tunnel barrier.

69. The structure of claim 66, wherein the tunnel barrier comprises a Mg—

ZnO tunnel barrier.

70. The structure of claim 66, wherein the magnetic tunnel junction has been annealed at a temperature greater than 300®

C.