Magnetic sensor stack body, method of forming the same, film formation control program, and recording medium

• US 8,810,974 B2
• Filed: 08/04/2010
• Issued: 08/19/2014
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: Canon Anelva Corporation (Canon Inc.)
• Original Assignee: Canon Anelva Corporation (Canon Inc.)
• Inventors: Endo, Tetsuya, Noel, Abarra Einstein, Suenaga, Masahiro, Ota, Yoshinori
• Primary Examiner(s): Miller, Brian
• Assistant Examiner(s): Garcia, Carlos E
• Application Number:
  US12/849,907
• Publication Number:
  US 20110032645A1
• Time in Patent Office: 1,476 Days
• Field of Search: 360/324, 360/326, 360/327.1, 360/327.2, 360/327.23, 360/327.3, 360/327.31
• US Class Current: 360/327.1
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• 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 5/3932 Magnetic biasing films
• CPC Class Codes: G11B 5/398 Specially shaped layers
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present invention is directed to align crystal c-axes in magnetic layers near two opposed junction wall faces of a magnetoresistive element so as to be almost perpendicular to the junction wall faces. A magnetic sensor stack body has, on a substrate, a magnetoresistive element whose electric resistance fluctuates when a bias magnetic field is applied and, on sides of opposed junction wall faces of the magnetoresistive element, field regions including magnetic layers for applying the bias magnetic field to the element. The magnetoresistive element has at least a ferromagnetic stack on a part of an antiferromagnetic layer, and width of an uppermost face of the ferromagnetic stack along a direction in which the junction wall faces are opposed to each other is smaller than width of an uppermost face of the antiferromagnetic layer in the same direction.

Claims

1. A magnetic sensor stack body comprising, on a substrate, a magnetoresistive element whose electric resistance fluctuates when a bias magnetic field is applied and, on sides of opposed junction wall faces of the magnetoresistive element, field regions including a magnetic layer for applying the bias magnetic field to the element,

wherein the magnetoresistive element has at least a ferromagnetic stack on a part of an antiferromagnetic layer,

wherein the ferromagnetic stack and the antiferromagnetic layer are stacked so as to form a stepwise form at both ends adjacent to opposed junction wall faces by forming the width of an uppermost face and a lowermost face of the ferromagnetic stack smaller than the width of an uppermost face of the antiferromagnetic layer, all widths being defined by the opposed junction wall faces, and

wherein the lowermost face of the ferromagnetic stack is a face that comes in contact with the antiferromagnetic layer.

2. The magnetic sensor stack body according to claim 1, wherein the width of the uppermost face of the antiferromagnetic layer is equal to or less than 2.5 times as large as that of the uppermost face of the ferromagnetic stack.

3. The magnetic sensor stack body according to claim 1, wherein the magnetic layer is made of Co—

Pt, Co—

Cr—

Pt, and an alloy having a hexagonal crystal structure (hcp) selected from a group of alloys of Co—

Pt and Co—

Cr—

Pt.

4. The magnetic sensor stack body according to claim 1, wherein the magnetic layer includes first and second magnetic layers having magnetic particles having crystal c-axes,

the first magnetic layer is disposed adjacent to the junction wall faces in the field regions, the crystal c-axes in the first magnetic layer are aligned and oriented along an ABS in a film plane,

the second magnetic layer is disposed adjacent to the first magnetic layer in the field regions, and the crystal c-axes direction in the second magnetic layer are distributed at random in a plane.

5. The magnetic sensor stack body according to claim 4, wherein the first magnetic layer is made of Fe—

Pt, Co—

Pt, and an alloy having a face-centered tetragonal structure (fct) selected from a group of alloys of Fe—

Pt and Co—

Pt, and

the second magnetic layer is made of Co—

Pt, Co—

Cr—

Pt, and an alloy having a hexagonal crystal structure selected from a group of alloys of Co—

Pt and Co—

Cr—

Pt.

6. The magnetic sensor stack body according to claim 1, wherein an underlayer made of Cr, Cr—

Mo, Cr—

Ti, Nb, Ta, W and an alloy having a body-centered cubic crystal structure (bcc) selected from a group of alloys of them is provided on the field regions and the junction wall faces, and

the underlayer has a thickness which is 3 to 8 nm in the field regions and is less than 3 nm in the junction wall faces.

7. The magnetic sensor stack body according to claim 1, wherein the field regions and the junction wall faces are provided with a first seed layer selected from CrB, CrTiB, MgO, Ru, Ta, and Ti and a group of alloys of them, and

the first seed layer has a thickness which is less than 1 nm in the field regions and is 0.5 to 2 nm in the junction wall faces.

8. The magnetic sensor stack body according to claim 1, wherein the field regions and the magnetoresistive element are covered with a first capping layer made of a material selected from Cr, Ru, Ta, Ti, a group of alloys of Cr, Ru, Ta, and Ti, and C.

9. The magnetic sensor stack body according to claim 8, wherein the field regions and the junction wall faces are provided with an insulating layer made of oxide or nitride, and

the insulating layer has a thickness of 2 to 5 nm on the junction wall faces.

10. The magnetic sensor stack body according to claim 9, wherein two separate shield layers made of a soft magnetic material are provided below the insulating layer and on the first capping layer.

11. The magnetic sensor stack body according to claim 1, wherein a layer of the ferromagnetic stack that comes in contact with the antiferromagnetic layer and the antiferromagnetic layer are stacked so as to form a stepwise form at both ends adjacent to opposed junction wall faces.

12. A method of forming a magnetic sensor stack body having, on a substrate, a stepwise-shaped magnetoresistive element having at least a ferromagnetic stack on a part of an antiferromagnetic layer and, in field regions on sides of opposed junction wall faces of the magnetoresistive element, a hard bias stack body for applying a bias magnetic field to the element, comprising:

a step of forming the antiferromagnetic layer and the ferromagnetic stack on the substrate;

a step of forming a pattern of a photoresist mask on the ferromagnetic stack;

a step of etching a part of the ferromagnetic stack;

a step of trimming the photoresist mask in a width direction;

a step of forming the stepwise-shaped magnetoresistive element by etching the ferromagnetic stack and the antiferromagnetic layer using the trimmed photoresist mask;

a step of forming a hard bias stack body in the field region; and

a step of planarizing the surface of the stepwise-shape magnetoresistive element and the hard bias stack body,

wherein the ferromagnetic stack and the antiferromagnetic layer are stacked so as to form a stepwise form at both ends adjacent to opposed junction wall faces by forming the width of an uppermost face and a lowermost face of the ferromagnetic stack smaller than the width of an uppermost face of the antiferromagnetic layer, all widths being defined by the opposed junction wall faces, and

wherein the lowermost face of the ferromagnetic stack is a face that comes in contact with the antiferromagnetic layer.

13. The method of forming a magnetic sensor stack body according to claim 12, wherein the step of forming the hard bias stack body comprises:

a step of forming an underlayer at a film forming angle Θ

₁ (Θ

₁=0 to 25 degrees) from the normal of the substrate;

a step of forming a first magnetic layer at a film forming angle Θ

₂ (Θ

₂=50 to 90 degrees) from the normal of the substrate;

a step of forming a second magnetic layer at a film forming angle Θ

₃ (Θ

₃=0 to 25 degrees) from the normal of the substrate; and

a step of forming a first capping layer at a film forming angle Θ

₄ (Θ

₄=0 to 45 degrees) from the normal of the substrate.

14. The method of forming a magnetic sensor stack body according to claim 12, further comprising a step of forming an insulating layer before the step of forming the hard bias stack body in the field region.

15. The method of forming a magnetic sensor stack body according to claim 12, further comprising a step of forming a second capping layer after the step of planarizing the surface of the magnetoresistive element and the hard bias stack body.

16. The method of forming a magnetic sensor stack body according to claim 15, further comprising a step of forming a shield layer after the step of forming the second capping layer.

17. The method of forming a magnetic sensor stack body according to claim 13, wherein the first magnetic layer is formed on one of junction wall faces of the magnetoresistive element while linearly moving the substrate at predetermined speed under an elongated target parallel to the junction wall faces of the magnetoresistive element,

the substrate is turned by 180 degrees around its center perpendicular axis as a center, and the first magnetic layer is formed on the other face of the junction wall faces while linearly moving the substrate at predetermined speed under the target.

18. The method of forming a magnetic sensor stack body according to claim 17, wherein the underlayer, the second magnetic layer, and the first capping layer are formed on one of field regions while linearly moving the substrate at predetermined speed under the target,

the substrate is turned by 180 degrees around its center perpendicular axis as a center, and the layers are formed on the other field region while linearly moving the substrate at predetermined speed under the target.

19. The method of forming a magnetic sensor stack body according to claim 12, wherein the hard bias stack body is formed by ion beam deposition.

20. The method of forming a magnetic sensor stack body according to claim 12, wherein a plurality of stepwise-shaped magnetoresistive elements are formed on the substrate, and the hard bias stack bodies in the plurality of magnetoresistive elements are stacked by the same procedure.

21. A magnetic sensor stack body comprising, on a substrate, a magnetoresistive element whose electric resistance fluctuates when a bias magnetic field is applied and, on sides of opposed junction wall faces of the magnetoresistive element, field regions including a magnetic layer for applying the bias magnetic field to the element,

wherein the magnetoresistive element has at least a ferromagnetic stack on a part of an antiferromagnetic layer,

wherein the ferromagnetic stack and the antiferromagnetic layer are stacked so as to form a stepwise form at both ends adjacent to opposed junction wall faces by forming the width of an uppermost face and a lowermost face of the ferromagnetic stack smaller than the width of an uppermost face of the antiferromagnetic layer, all widths being defined by the opposed junction wall faces,

wherein the portions in contact with the junction wall faces in the stepwise form of the magnetic layer have a corresponding stepwise shape, and

wherein the lowermost face of the ferromagnetic stack is a face that comes in contact with the antiferromagnetic layer.

22. The magnetic sensor stack body according to claim 21, wherein the width of the uppermost face of the antiferromagnetic layer is equal to or less than 2.5 times as large as that of the uppermost face of the ferromagnetic stack.

23. The magnetic sensor stack body according to claim 21, wherein the magnetic layer is made of Co—

Pt, Co—

Cr—

Pt, and an alloy having a hexagonal crystal structure (hcp) selected from a group of alloys of Co—

Pt and Co—

Cr—

Pt.

24. The magnetic sensor stack body according to claim 21, wherein the magnetic layer includes first and second magnetic layers having magnetic particles having crystal c-axes,

the first magnetic layer is disposed adjacent to the junction wall faces in the field regions, the crystal c-axes in the first magnetic layer are aligned and oriented along an ABS in a film plane,

the second magnetic layer is disposed adjacent to the first magnetic layer in the field regions, and the crystal c-axes direction in the second magnetic layer are distributed at random in a plane.

25. The magnetic sensor stack body according to claim 24, wherein the first magnetic layer is made of Fe—

Pt, Co—

Pt, and an alloy having a face-centered tetragonal structure (fct) selected from a group of alloys of Fe—

Pt and Co—

Pt, and

the second magnetic layer is made of Co—

Pt, Co—

Cr—

Pt, and an alloy having a hexagonal crystal structure selected from a group of alloys of Co—

Pt and Co—

Cr—

Pt.

26. The magnetic sensor stack body according to claim 21, wherein an underlayer made of Cr, Cr—

Mo, Cr—

Ti, Nb, Ta, W and an alloy having a body-centered cubic crystal structure (bcc) selected from a group of alloys of them is provided on the field regions and the junction wall faces, and

the underlayer has a thickness which is 3 to 8 nm in the field regions and is less than 3 nm in the junction wall faces.

27. The magnetic sensor stack body according to claim 21, wherein the field regions and the junction wall faces are provided with a first seed layer selected from CrB, CrTiB, MgO, Ru, Ta, and Ti and a group of alloys of them, and

the first seed layer has a thickness which is less than 1 nm in the field regions and is 0.5 to 2 nm in the junction wall faces.

28. The magnetic sensor stack body according to claim 21, wherein the field regions and the magnetoresistive element are covered with a first capping layer made of a material selected from Cr, Ru, Ta, Ti, a group of alloys of Cr, Ru, Ta, and Ti, and C.

29. The magnetic sensor stack body according to claim 28, wherein the field regions and the junction wall faces are provided with an insulating layer made of oxide or nitride, and

the insulating layer has a thickness of 2 to 5 nm on the junction wall faces.

30. The magnetic sensor stack body according to claim 29, wherein two separate shield layers made of a soft magnetic material are provided below the insulating layer and on the first capping layer.