GMR configuration with enhanced spin filtering

• US 6,770,382 B1
• Filed: 11/22/1999
• Issued: 08/03/2004
• Est. Priority Date: 11/22/1999
• Status: Expired due to Fees

• Current Assignee: Headway Technologies Incorporated (TDK Corporation)
• Original Assignee: Headway Technologies Incorporated (TDK Corporation)
• Inventors: Horng, Cheng, Ju, Kochan, Dieny, Bernard, Chen, Mao-Min, Chang, Jei-Wei, Liao, Simon
• Primary Examiner(s): LA VILLA, MICHAEL EUGENE
• Application Number:
  US09/443,447
• Time in Patent Office: 1,716 Days
• Field of Search: 428/632, 428/692, 428/693, 428/670, 428/674, 428/675, 428/676, 428/678, 428/679, 428/680, 428/681, 428/694.T, 428/694.TM, 428/900, 428/212, 428/213, 428/220, 360/113, 360/324.11, 360/324.12, 360/313, 360/324.1, 324/252, 338/32.R, 427/127, 427/128, 427/132, 427/101, 427/103, 427/123, 427/126.3
• US Class Current: 428/811.3
• 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: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/3133 including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure G11B5/3106 takes precedence
• 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: H01F 10/30 characterised by the composition of the intermediate layers , e.g. seed, buffer, template, diffusion preventing, cap layers H01F10/06 and H01F10/32 take precedence
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: Y10T 428/1121 Multilayer
• CPC Class Codes: Y10T 428/1129 Super lattice [e.g., giant magneto resistance [GMR] or colossal magneto resistance [CMR], etc.]
• CPC Class Codes: Y10T 428/1157 Substrate composition
• CPC Class Codes: Y10T 428/1171 with defined laminate structural detail
• CPC Class Codes: Y10T 428/12944 Ni-base component
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]

Abstract

A Spin Valve GMR and Spin Filter SVGMR configuration where in the first embodiment an important buffer layer is composed of an metal oxide having a crystal lattice constant that is close the 1^st FM free layer'"'"'s crystal lattice constant and has the same crystal structure (e.g., FCC, BCC, etc.). The metal oxide buffer layer enhances the specular scattering. The spin valve giant magnetoresistance (SVGMR) sensor comprises: a seed layer over the substrate. An important metal oxide buffer layer (buffer layer) over the seed layer. The metal oxide layer preferably is comprised of NiO or alpha-Fe2O₃. A free ferromagnetic layer over the metal oxide layer. A non-magnetic conductor spacer layer over the free ferromagnetic layer. A pinned ferromagnetic layer (2^nd FM pinned) over the non-magnetic conductor spacer layer and a pinning material layer over the pinned ferromagnetic layer. In the second embodiment, a high conductivity layer (HCL) is formed over the buffer layer to create a spin filter -SVGMR. The HCL layer enhances the GMR ratio of the spin filter SVGMR. The third embodiment is a pinned FM layer comprised of a three layer structure of an lower AP layer, a spacer layer (e.g., Ru) and an upper AP layer.

Claims

1. A spin valve giant magnetoresistance (SVGMR) sensor comprising:

a seed layer over a substrate, said seed layer formed of a material selected from the group consisting of nickel chromium alloys, nickel -chromium-copper alloys and nickel-iron-chromium alloys;

a metal oxide buffer layer over the seed layer;

said metal oxide buffer layer is comprised of alpha—

Fe₂O₃ and has a thickness of between about 5 to 15 Å

;

a free ferromagnetic layer over said metal oxide buffer layer;

said metal oxide buffer layer and said free ferromagnetic layer have about the same crystal lattice constants; and

said metal oxide buffer layer and said free ferromagnetic layer have the same crystal structure;

a non-magnetic conductor spacer layer over said free ferromagnetic layer;

a pinned ferromagnetic layer over the non-magnetic conductor spacer layer; and

a pinning material layer over the pinned ferromagnetic layer; and

a capping layer over said pinning material layer.

2. The spin valve giant magnetoresistance (SVGMR) sensor of claim 1 which further includes:

a high conductivity layer on said metal oxide buffer layer and said free ferromagnetic layer on said high conductivity layer.

3. The spin valve giant magnetoresistance (SVGMR) sensor of claim 1 which further includes:

a high conductivity layer on said metal oxide buffer layer and said free ferromagnetic layer on said high conductivity layer (HCL);

said high conductivity layer is comprised of Cu or Cu—

Ni and has a thickness between 10 and 30 Å

.

4. The method of claim 1 wherein said pinned ferromagnetic layer is composed of a three layer structure comprising:

(a) a lower AP layer, a middle non-magnetic conductor spacer layer and a upper AP layer wherein said middle non-magnetic conductor spacer layer induces anti-ferromagnetic coupling between said lower AP layer and said upper AP layer which enhances the Pinning effect.

5. The spin valve giant magnetoresistance sensor of claim 1 wherein said pinned ferromagnetic layer is composed of a three layer structure comprising:

(a) a lower AP layer, (b) a Ru layer and (c) an upper AP layer wherein said Ru layer induces anti-ferromagnetic coupling between said lower AP layer and said AP upper which enhances the pinning effect and where said lower AP layer and said upper AP layer have a thickness of between about 5 and 20 Å and

are comprised of CoFe and said Ru layer has a thickness of between about 5 and 10 Å

.

6. The spin valve giant magnetoresistance sensor of claim 1 wherein said seed layer is comprised of:

NiFeCr.

7. The spin valve giant magnetoresistance sensor of claim 1 wherein said free ferromagnetic layer is comprised of:

CoFe, CoFe/NiFe, or Co/NiFe and has a thickness of 20 to 30 Å

.

8. The spin valve giant magnetoresistance sensor of claim 1 wherein said non-magnetic conductor spacer layer is composed of Cu having a thickness of between about 20 and 30 Å

.

9. The spin valve giant magnetoresistance sensor of claim 1 wherein the free ferromagnetic material layer and the pinned ferromagnetic material layer are each formed of a ferromagnetic material selected from the group consisting of nickel, iron and cobalt ferromagnetic materials, alloys thereof, laminates thereof and laminates of alloys thereof.

10. The spin valve giant magnetoresistance (SVGMR) sensor of claim 1 wherein said pinned ferromagnetic layer is comprised of a material selected from the group consisting of CoFe, and Co;

and has a thickness of between about 10 and 30 Å

.

11. The spin valve giant magnetoresistance (SVGMR) sensor of claim 1 wherein a pinning material layer is comprised of a material selected from the group consisting of MnPt, IrMn, and MnNi;

and has a thickness of between about 50 and 300 Å

.

12. The spin valve giant magnetoresistance (SVGMR) sensor of claim 1 wherein said capping layer consists of a material selected from the group consisting of:

MiFeCo, NiCr, and Ta, and has a thickness of between about 40 and 60 Å

.