High performance magnetic tunnel barriers with amorphous materials

• US 7,807,218 B2
• Filed: 07/26/2007
• Issued: 10/05/2010
• 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): Cleveland; Michael
• Assistant Examiner(s): TADAYYON ESLAMI, TABASSOM
• Application Number:
  US11/829,038
• Publication Number:
  US 20100028530A1
• Time in Patent Office: 1,167 Days
• Field of Search: 428/811.1, 428/811.5, 428/812, 428/813, 360/324.2, 427/130, 427/131
• US Class Current: 427/128
• 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 barrier. 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 method, comprising:

forming a tunnel barrier selected from the group of tunnel barriers consisting of MgO and Mg—

ZnO;

forming an amorphous ferromagnetic layer by depositing Co and at least one other element on an underlayer, wherein the amorphous layer and the tunnel barrier are formed in proximity to one another to permit spin-polarized current to be passed between the tunnel barrier and the amorphous layer; and

forming an additional magnetic layer, so that the additional magnetic layer, the tunnel barrier, and the amorphous ferromagnetic layer form a magnetic tunnel junction having a tunnel magnetoresistance of greater than 100% at room temperature.

2. The method of claim 1, wherein the underlayer includes the tunnel barrier.

3. The method of claim 2, wherein the amorphous ferromagnetic layer is formed directly on the tunnel barrier.

4. The method of claim 1, wherein the amorphous ferromagnetic layer includes a thin crystalline layer that is in contact with the tunnel barrier.

5. The method of claim 1, wherein the tunnel barrier is (100) oriented.

6. The method of claim 1, wherein the additional magnetic layer has a body centered cubic structure.

7. The method of claim 1, further comprising annealing the junction to improve its tunneling magnetoresistance.

8. The method of claim 1, wherein the magnetic tunnel junction is sufficiently free of defects and deleterious oxide that the magnetic tunnel junction has a tunnel magnetoresistance of greater than 120% at room temperature.

9. The method of claim 1, wherein the junction is annealed at a temperature selected to yield a tunnel magnetoresistance of greater than 160% at room temperature.

10. The method of claim 1, wherein the junction is annealed at a temperature selected to yield a tunnel magnetoresistance of greater than 200% at room temperature.

11. The method of claim 1, wherein the junction is annealed at a temperature greater than 300°

C.

12. The method of claim 1, wherein the junction is annealed at a temperature greater than 340°

C.

13. The method of claim 1, wherein the junction is annealed at a temperature in the range of 300°

C. to 400°

C.

14. The method of claim 1, wherein the tunnel barrier is formed on an underlayer that includes the amorphous layer.

15. The method of claim 14, wherein the tunnel barrier is formed directly on the amorphous layer.

16. The method of claim 1, comprising depositing Fe onto the tunnel barrier, the amorphous layer including Co, Fe, and said at least one other element.

17. The method of claim 16, wherein said at least one other element includes B.

18. The method of claim 16, wherein said at least one other element includes Zr.

19. The method of claim 16, wherein said at least one other element includes Hf.

20. The method of claim 1, wherein the tunnel barrier includes a MgO tunnel barrier.

21. The method of claim 20, wherein the MgO tunnel barrier is formed by:

depositing Mg onto a surface of an underlayer to form a Mg layer thereon, wherein the surface is selected to be substantially free of oxide; and

directing additional Mg, in the presence of oxygen, towards the Mg layer to form a MgO tunnel barrier in contact with the underlayer, the oxygen reacting with the additional Mg and the Mg layer.

22. The method of claim 1, wherein the tunnel barrier includes a Mg—

ZnO tunnel barrier.

23. The method of claim 22, wherein the Mg—

ZnO tunnel barrier is formed by;

depositing a metal layer onto a surface of an underlayer, wherein the surface is selected to be substantially free of oxide; and

directing additional metal towards the metal layer, in the presence of oxygen, to form a magnesium-zinc oxide tunnel barrier in contact with the underlayer, the oxygen reacting with the additional metal and the metal layer, wherein;

at least one of the metal layer and the additional metal includes Zn, and

at least one of the metal layer and the additional metal includes Mg.