Magnetoresistive thin-film magnetic element and method for making the same

• US 20010038927A1
• Filed: 04/04/2001
• Published: 11/08/2001
• Est. Priority Date: 04/06/2000
• Status: Active Grant

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Hasewaga, Naoya
• Granted Patent: US 6,656,604 B2
• Time in Patent Office: Days
• US Class Current: 428/692
• 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 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• 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 41/308 lift-off processes, e.g. ion milling, for trimming or patterning
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10S 428/928 Magnetic property
• CPC Class Codes: Y10T 428/11 Magnetic recording head
• CPC Class Codes: Y10T 428/1107 Magnetoresistive
• CPC Class Codes: Y10T 428/1121 Multilayer
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape
• CPC Class Codes: Y10T 428/12542 More than one such component
• CPC Class Codes: Y10T 428/12576 Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/1259 Oxide
• CPC Class Codes: Y10T 428/12611 : Oxide-containing component
• CPC Class Codes: Y10T 428/1266 : O, S, or organic compound in metal component
• CPC Class Codes: Y10T 428/12674 : Ge- or Si-base component
• CPC Class Codes: Y10T 428/12854 : Next to Co-, Fe-, or Ni-base component
• CPC Class Codes: Y10T 428/12861 : Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12875 : Platinum group metal-base component
• CPC Class Codes: Y10T 428/12931 : Co-, Fe-, or Ni-base components, alternative to each other

Abstract

A magnetoresistive thin-film magnetic element including a composite comprising an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer; hard bias layers for orienting the magnetic vectors of the free magnetic layer in a direction substantially orthogonal to the magnetization vector of the pinned magnetic layer; and a conductive layer for supplying a sense current is provided. The hard bias layers are provided at the two sides of the free magnetic layer. The hard bias layers and the free magnetic layers are in contact with each other at least partly. Bias underlayers are provided at the bottom of the hard bias layers.

Claims

1. A magnetoresistive thin-film magnetic element comprising:

a composite comprising an antiferromagnetic layer, a pinned magnetic layer having a first magnetization vector pinned by an exchange anisotropic magnetic field with the antiferromagnetic layer, and a nonmagnetic conductive layer formed between the pinned magnetic layer and a free magnetic layer, the free magnetic layer having a second magnetization vector;

hard bias layers formed on two sides of the free magnetic layer so that at least part of each hard bias layer is in direct contact with the free magnetic layer, wherein the hard bias layers orient the second magnetization vector of the free magnetic layer in a direction substantially orthogonal to the first magnetization vector of the pinned magnetic layer;

a conductive layer to supply a sense current to the free magnetic layer, the nonmagnetic conductive layer, and the pinned magnetic layer; and

bias underlayers each provided under each of the hard bias layers, wherein the bias underlayers control the crystal orientation of the hard bias layers.

2. A magnetoresistive thin-film magnetic element according to

claim 1

, wherein the magnetoresistive thin-film magnetic element is of a dual type in which the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer are provided on each of opposite sides in the thickness direction of the free magnetic layer.

3. A magnetoresistive thin-film magnetic element according to

claim 1

, the composite further comprising at least one nonmagnetic interlayer which separates at least one of the pinned magnetic layer and the free magnetic layer into two sublayers, wherein the two sublayers are in a ferri-magnetic state in which magnetization vectors of the two sublayers are antiparallel to each other.

4. A magnetoresistive thin-film magnetic element according to

claim 2

, the composite further comprising at least one nonmagnetic interlayer which separates at least one of the pinned magnetic layer and the free magnetic layer into two sublayers, wherein the two sublayers are in a ferri-magnetic state in which magnetization vectors of the two sublayers are antiparallel to each other.

5. A magnetoresistive thin-film magnetic element according to

claim 1

, wherein each of the bias underlayers has an extension extending to the interface between the free magnetic layer and each of at least two hard bias layers provided at the two sides of the free magnetic layer.

6. A magnetoresistive thin-film magnetic element according to

claim 2

, wherein each of the bias underlayers has an extension extending to the interface between the free magnetic layer and each of the hard bias layers provided at the two sides of the free magnetic layer.

7. A magnetoresistive thin-film magnetic element according to

claim 5

, wherein the thickness of the extension of each of the bias underlayers is less than or equal to about 1 nm.

8. A magnetoresistive thin-film magnetic element according to

claim 6

, wherein the thickness of the extension of each of the bias underlayers is less than or equal to about 1 nm.

9. A magnetoresistive thin-film magnetic element according to

claim 1

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

10. A magnetoresistive thin-film magnetic element according to

claim 2

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

11. A magnetoresistive thin-film magnetic element according to

claim 7

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

12. A magnetoresistive thin-film magnetic element according to

claim 8

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

13. A magnetoresistive thin-film magnetic element according to

claim 9

, wherein the bias underlayers comprise chromium.

14. A magnetoresistive thin-film magnetic element according to

claim 10

, wherein the bias underlayers comprise chromium.

15. A magnetoresistive thin-film magnetic element according to

claim 11

, wherein the bias underlayers comprise chromium.

16. A magnetoresistive thin-film magnetic element according to

claim 12

, wherein the bias underlayers comprise chromium.

17. A magnetoresistive thin-film magnetic element according to

claim 1

, wherein the hard bias layers form slope angles along two side portions of the composite, wherein the slope angles are greater than or equal to about 30 degrees.

18. A magnetoresistive thin-film magnetic element according to

claim 2

, wherein the hard bias layers form slope angles along two side portions of the composite, wherein the slope angles are greater than or equal to about 30 degrees.

19. A magnetoresistive thin-film magnetic element comprising:

a composite comprising an antiferromagnetic layer, a pinned magnetic layer having a first magnetization vector being pinned by an exchange anisotropic magnetic field with the antiferromagnetic layer, a nonmagnetic conductive layer formed between the pinned magnetic layer and a free magnetic layer, the free magnetic layer having a second magnetization vector;

hard bias layers formed at two sides of the composite, wherein the hard bias layers orient the second magnetization vector of the free magnetic layer in a direction substantially orthogonal to the first magnetization vector of the pinned magnetic layer;

a conductive layer to supply a sense current to the free magnetic layer, the nonmagnetic conductive layer, and the pinned magnetic layer; and

bias underlayers each provided under each of the hard bias layers, wherein each bias underlayer has a portion extending to the interface between the free magnetic layer and each of the hard bias layers, wherein the portion controls the crystal orientation of the hard bias layers,

wherein the thickness of each of the hard bias underlayers is smaller at the interface between the free magnetic layer and each of the hard bias layers than under the hard bias layers.

20. A magnetoresistive thin-film magnetic element according to

claim 19

, wherein the magnetoresistive thin-film magnetic element is of a dual type in which the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer are provided on each of opposite sides in the thickness direction of the free magnetic layer.

21. A magnetoresistive thin-film magnetic element according to

claim 19

, the composite further comprising at least one nonmagnetic interlayer which separates at least one of the pinned magnetic layer and the free magnetic layer into two sublayers, wherein the two sublayers are in a ferri-magnetic state in which magnetization vectors of the two sublayers are antiparallel to each other.

22. A magnetoresistive thin-film magnetic element according to

claim 20

, the composite further comprising at least one nonmagnetic interlayer which separates at least one of the pinned magnetic layer and the free magnetic layer into two sublayers, wherein the two sublayers are in a ferri-magnetic state in which magnetization vectors of the two sublayers are antiparallel to each other.

23. A magnetoresistive thin-film magnetic element according to

claim 19

, wherein the thickness of the portion of each of the bias underlayers extending to the interface between the free magnetic layer and each of the hard bias layers is less than or equal to about 1 nm.

24. A magnetoresistive thin-film magnetic element according to

claim 20

, wherein the thickness of each of the bias underlayers is less than or equal to about 1 nm at the interface between the free magnetic layer and each of the hard bias layers.

25. A magnetoresistive thin-film magnetic element according to

claim 19

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

26. A magnetoresistive thin-film magnetic element according to

claim 20

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

27. A magnetoresistive thin-film magnetic element according to

claim 23

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

28. A magnetoresistive thin-film magnetic element according to

claim 24

, wherein the bias underlayers comprise a nonmagnetic metal having a body-centered cubic structure.

29. A magnetoresistive thin-film magnetic element according to

claim 25

, wherein the bias underlayers comprise of chromium.

30. A magnetoresistive thin-film magnetic element according to

claim 26

, wherein the bias underlayers comprise of chromium.

31. A magnetoresistive thin-film magnetic element according to

claim 27

, wherein the bias underlayers comprise of chromium.

32. A magnetoresistive thin-film magnetic element according to

claim 28

, wherein the bias underlayers comprise of chromium.

33. A magnetoresistive thin-film magnetic element according to

claim 19

, wherein the hard bias layers form slope angles along two side portions of the composite, wherein the slope angles are greater than or equal to about 30 degrees.

34. A magnetoresistive thin-film magnetic element according to

claim 20

, wherein the hard bias layers form slope angles along two side portions of the composite, wherein the slope angles are greater than or equal to 30 degrees.

35. A method for making a magnetoresistive thin-film magnetic element comprising:

forming a composite layer on a substrate, the composite layer comprising an antiferromagnetic layer, a pinned magnetic layer in contact with the antiferromagnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, wherein a magnetization vector of the pinned magnetic layer is pinned by an exchange coupling magnetic field with the antiferromagnetic layer;

applying a lift-off resist on the composite layer;

removing the area not covered by the lift-off resist by an ion milling to form a substantially trapezoidal composite;

forming bias underlayers to control the crystal orientation of hard bias layers at the two sides of the composite;

arranging a first target to one of oppose the substrate to be parallel to each other and oppose the substrate so that the angle defined by the first target and the substrate is smaller than the angle defined by a second target and the substrate during formation of the hard bias layers;

forming the hard bias layers on the bias underlayers, wherein the hard bias layers orient the magnetization vector of the free magnetic layer in the direction substantially orthogonal to the pinned magnetic layer;

arranging the second target to oppose the substrate so that the angle defined by the second target and the substrate is larger than the angle defined by the first target and the substrate; and

forming conductive layers on the hard bias layers;

arranging a third target to oppose the substrate so that the angle defined by the third target and the substrate is larger than the angle defined by the second target and the substrate.

36. A method for making a magnetoresistive thin-film magnetic element according to

claim 35

, wherein forming the bias underlayers comprises at least one of an ion beam sputtering process, a long-throw sputtering process, and a collimation sputtering process.

37. A method for making a magnetoresistive thin film magnetic element according to

claim 35

, wherein forming the hard bias layers comprises at least one of an ion beam sputtering process, a long-throw sputtering process, and a collimation sputtering process.

38. A method for making a magnetoresistive thin film magnetic element according to

claim 35

wherein forming conductive layers comprises at least one of an ion beam sputtering process, a long-throw sputtering process, and a collimation sputtering process.

39. A method for making a magnetoresistive thin-film magnetic element according to

claim 35

, further comprising:

optimizing the angle defined by the first target and the substrate so as to form the bias underlayers on the substrate at the two sides of the composite and on parts of the side surfaces at the two sides of the free magnetic layer; and

forming the hard bias layers so that end portions of the hard bias layers and side portions of the free magnetic layer of the composite contact each other at least partly.

40. A method for making a magnetoresistive thin-film magnetic element according to

claim 35

, further comprising:

optimizing the angle defined by the first target and the substrate so as to form the bias underlayers on the substrate at the two sides of the composite and on the side surfaces of the free magnetic layer, and forming the hard bias layers at the interfaces between the two sides of the free magnetic layer of the composite and the end portions of the hard bias layers.

41. A method for making a magnetoresistive thin-film magnetic element according to

claim 35

, further comprising forming slope angles along side portions of the composite, wherein the slope angles are greater than or equal to 30 degrees.