Boron doped CoFe for GMR free layer

• US 20040047086A1
• Filed: 09/10/2002
• Published: 03/11/2004
• Est. Priority Date: 09/10/2002
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Torng, Chyu-Jiuh, Wang, Hui-Chuan, Li, Yun-Fei
• Granted Patent: US 6,844,999 B2
• Time in Patent Office: Days
• US Class Current: 360/324.12
• 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: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/313 Disposition of layers
• CPC Class Codes: G11B 5/3163 Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

Prior art gains in GMR ratio resulting from use of NiFeCr as a seed layer were offset by the resulting high values obtained for H_c and H_k. This problem has been overcome by combining a seed layer of NiCr or NiFeCr with a free layer of boron doped CoFe. Additionally, when using a synthetic pinned layer, further improvement is achieved by using boron doped CoFe for the two antiparallel layers.

Claims

1. A process to manufacture a bottom spin valve, comprising:

providing a substrate and depositing thereon a seed layer that contains Ni and Cr;

depositing an antiferromagnetic layer on said seed layer;

depositing a pinned layer on said antiferromagnetic layer;

depositing a non-magnetic spacer layer on said pinned layer;

on said non-magnetic spacer layer, depositing a free layer consisting of boron doped cobalt-iron; and

depositing a capping layer on said free layer.

2. The process described in claim 1 wherein said seed layer is selected from the group consisting of NiCr and NiFeCr.

3. The process described in claim 1 wherein the step of depositing said pinned layer further comprises depositing a layer of ruthenium between two layers of boron doped cobalt-iron and then magnetizing said layers of boron doped cobalt-iron in opposing directions.

4. The process described in claim 3 wherein said two layers of boron doped cobalt-iron each contains between about 50 and 90 atomic % cobalt, between about 5 and 30 atomic % iron, and between about 3 and 20 atomic % boron.

5. The process described in claim 3 further comprising depositing a layer of NiFe between said free layer and said capping layer.

6. The process described in claim 1 wherein said free layer contains between about 70 and 90 atomic % cobalt, between about 5 and 10 atomic % iron, and between about 3 and 20 atomic % boron.

7. The process described in claim 1 wherein said free layer has a thickness that is in the range of from about 15 to 100 Angstroms and a coercivity that varies by less than about 10% over said thickness range.

8. The process described in claim 1 wherein said free layer has a coercivity that is between about 2 and 5 Oersted.

9. The process described in claim 1 wherein said free layer has an interlayer coupling between said free layer and said pinned layer that is less than about 10 Oersted.

10. The process described in claim 1 wherein said free layer has an anisotropy field that is between about 3 and 5 Oersted.

11. The process described in claim 1 wherein said spin valve has a GMR ratio that is between about 10 and 15%.

12. The process described in claim 1 wherein said spin valve has a seed layer that is NiCr and a GMR ratio that is between about 10 and 15% and a free layer having a coercivity that is between about 2 and 5 Oersted and said free layer has an anisotropy field between about 3 and 5 Oersted.

13. The process described in claim 1 wherein said spin valve has a seed layer that is NiFeCr and a GMR ratio that is between about 10 and 15% and a free layer having a coercivity that is between about 2 and 5 Oersted and said free layer has an anisotropy field between about 3 and 5 Oersted.

14. A bottom spin valve, comprising:

a substrate on which is a seed layer that is NiCr;

on said seed layer, an antiferromagnetic layer;

on said antiferromagnetic layer, a pinned layer;

on said pinned layer, a non-magnetic spacer layer;

on said non-magnetic spacer layer, a free layer consisting of boron doped cobalt-iron; and

a capping layer on said free layer.

15. The bottom spin valve described in claim 14 wherein said pinned layer further comprises a layer of ruthenium between two magnetically antiparallel layers of boron doped cobalt-iron.

16. The bottom spin valve described in claim 15 wherein said two layers of boron doped cobalt-iron each contains between about 50 and 90 atomic % cobalt, between about 5 and 30 atomic % iron, and between about 3 and 20 atomic % boron.

17. The bottom spin valve described in claim 14 wherein said free layer contains between about 70 and 90 atomic % cobalt, between about 5 and 10 atomic % iron, and between about 3 and 20 atomic % boron.

18. The bottom spin valve described in claim 14 wherein said free layer has a thickness that is in the range of from about 15 to 100 Angstroms and a coercivity that varies by less than about 10% over said thickness range.

19. The bottom spin valve described in claim 14 wherein said free layer has a coercivity that is between about 2 and 5 Oersted.

20. The bottom spin valve described in claim 14 wherein said free layer has an interlayer coupling between said free layer and said pinned layer that is less than about 10 Oersted.

21. The bottom spin valve described in claim 14 wherein said free layer has an anisotropy field that is between about 3 and 5 Oersted.

22. The bottom spin valve described in claim 14 wherein said spin valve has a GMR ratio that is between about 10 and 15% and its free layer has a coercivity that is between about 2 and 5 Oersted.

23. A bottom spin valve, comprising:

a substrate on which is a seed layer that is NiFeCr;

on said seed layer, an antiferromagnetic layer;

on said antiferromagnetic layer, a pinned layer;

on said pinned layer, a non-magnetic spacer layer;

on said non-magnetic spacer layer, a free layer consisting of boron doped cobalt-iron; and

a capping layer on said free layer.

24. The bottom spin valve described in claim 23 wherein said pinned layer further comprises a layer of ruthenium between two magnetically antiparallel layers of boron doped cobalt-iron.

25. The bottom spin valve described in claim 24 wherein said two layers of boron doped cobalt-iron each contains between about 50 and 90 atomic % cobalt, between about 5 and 30 atomic % iron, and between about 3 and 20 atomic % boron.

26. The bottom spin valve described in claim 23 wherein said free layer contains between about 70 and 90 atomic % cobalt, between about 5 and 10 atomic % iron, and between about 3 and 20 atomic % boron.

27. The bottom spin valve described in claim 23 wherein said free layer has a thickness that is in the range of from about 15 to 100 Angstroms and a coercivity that varies by less than about 10% over said thickness range.

28. The bottom spin valve described in claim 23 wherein said free layer has a coercivity that is between about 2 and 5 Oersted.

29. The bottom spin valve described in claim 23 wherein said free layer has an interlayer coupling between said free layer and said pinned layer that is less than about 10 Oersted.

30. The bottom spin valve described in claim 23 wherein said free layer has an anisotropy field that is between about 3 and 5 Oersted.

31. The bottom spin valve described in claim 23 wherein said spin valve has a GMR ratio that is between about 10 and 15% and its free layer has a coercivity that is between about 2 and 5 Oersted.