MAGNETIC SENSOR STACK BODY, METHOD OF FORMING THE SAME, FILM FORMATION CONTROL PROGRAM, AND RECORDING MEDIUM

• US 20110032645A1
• Filed: 08/04/2010
• Published: 02/10/2011
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: Canon Anelva Corporation (Canon Inc.)
• Original Assignee: Canon Anelva Corporation (Canon Inc.)
• Inventors: NOEL, Abarra Einstein, Ota, Yoshinori, Endo, Tetsuya, Suenaga, Masahiro
• Granted Patent: US 8,810,974 B2
• Time in Patent Office: Days
• US Class Current: 360/326
• 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 magnetic layers 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, 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.

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 face in the field region, 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 region, 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 region and the junction wall faces, and

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

7. The magnetic sensor stack body according to claim 1, wherein the field region and the junction wall face 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 region and is 0.5 to 2 nm in the junction wall face.

8. The magnetic sensor stack body according to claim 1, wherein the field region 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 1, wherein the field region and the junction wall face 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 face.

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

11. 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 two 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.

12. The method of forming a magnetic sensor stack body according to claim 11, wherein in the stepwise-shaped magnetoresistive element, width of an uppermost face of the ferromagnetic stack along a direction in which the junction wall faces are opposed to each other is set to be smaller than width of an uppermost face of the antiferromagnetic layer along the direction in which the junction wall faces are opposed to each other.

13. The method of forming a magnetic sensor stack body according to claim 11, 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 11, 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 11, 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 11, 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 11, 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 at least an underlayer having a body-centered cubic crystal structure (bcc) is provided on the field region,

the magnetic layer is formed on the underlayer, and

the magnetic layer is made of a Co—

Pt-based alloy having a hexagonal crystal structure (hcp), has no gaps in the layer, has a (10.0) lattice plane, and a squareness ratio exceeding 0.9 along ABS.

22. The magnetic sensor stack body according to claim 21, further comprising an insulating layer made of oxide or nitride on the field region,

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

23. The magnetic sensor stack body according to claim 22, further comprising a second seed layer made of a metal nitride between the insulating layer and the underlayer.

24. The magnetic sensor stack body according to claim 23, wherein total thickness of the second seed layer and the underlayer is less than 10 nm,

thickness of the magnetic layer is 10 to 30 nm, and

a coercive force orientation ratio (OR) of a hard bias stack body including those layers exceeds 1.5.

25. The magnetic sensor stack body according to claim 21, wherein the underlayer is made of a material selected from Cr, Ti, Nb, Ta, W, Ru, Al, and a group of alloys of Cr, Ti, Nb, Ta, W, Ru, and Al, has a thickness of 3 to 8 nm on the field region, and has a thickness which is less than 3 nm on the junction wall face.

26. The magnetic sensor stack body according to claim 23, wherein the second seed layer is made of a material selected from Ta—

N, Nb—

N, or RuAl—

N, has a thickness of 3 to 8 nm on the field region, and has a thickness which is less than 3 nm on the junction wall face.

27. The magnetic sensor stack body according to claim 23, wherein the second seed layer is made of Ta—

N, and the underlayer is made of W—

Ti (0<

Ti<

30 atomic %) and has a thickness of 3 to 5 nm.

28. The magnetic sensor stack body according to claim 21, wherein the field region 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, further comprising a shield layer made of a soft magnetic material under the insulating layer and on the first capping layer.

30. A method of forming a magnetic sensor stack body having, on a substrate, a magnetoresistive element whose electric resistance fluctuates when a bias magnetic field is applied and, in field regions on sides of opposed two junction wall faces of the magnetoresistive element, forming a hard bias stack body for applying a bias magnetic field to the element, comprising at least:

a step of obliquely forming an underlayer along a direction of the junction wall faces at a film forming angle exceeding 45 degrees and less than 90 degrees from a normal of the substrate; and

a step of forming a magnetic layer on the underlayer at a film forming angle of 0 to 30 degrees from the normal of the substrate.

31. The method of forming a magnetic sensor stack body according to claim 30, wherein in a state where junction wall faces of the magnetoresistive element on the substrate are disposed so as to be perpendicular to a target,

the underlayer is obliquely formed on the junction wall faces and the field region while moving the substrate at predetermined speed under the target,

the substrate is turned by 180 degrees, and the underlayer is obliquely formed on the junction wall faces and the field region while moving the substrate under the target.

32. The method of forming a magnetic sensor stack body according to claim 30, further comprising a step of forming an insulating layer on the field region and the junction wall faces before the step of obliquely forming the underlayer.

33. The method of forming a magnetic sensor stack body according to claim 32, further comprising a step of obliquely forming a second seed layer made of a metal nitride on the insulating layer along a direction of the junction wall faces at a film forming angle exceeding 45 degrees and less than 90 degrees from normal of the substrate after the step of forming the insulating layer.

34. The method of forming a magnetic sensor stack body according to claim 33, wherein in a state where junction wall faces of the magnetoresistive element on the substrate are disposed so as to be perpendicular to a target,

the second seed layer is obliquely formed on the junction wall faces and the field region while moving the substrate at predetermined speed under the target,

the substrate is turned by 180 degrees, and the second seed layer is obliquely formed on the junction wall faces and the field region while moving the substrate under the target.

35. The method of forming a magnetic sensor stack body according to claim 33, wherein the second seed layer is formed by reaction in treatment gas and N₂ atmosphere, and partial pressure of N₂ is 10 to 30%.

36. The method of forming a magnetic sensor stack body according to claim 30, further comprising a step of forming a first capping layer at a film forming angle of 0 to 30 degrees from normal of the substrate after the step of forming the magnetic layer.

37. The method of forming a magnetic sensor stack body according to claim 36, further comprising a step of forming a shield layer after the step of forming the first capping layer.

38. The method of forming a magnetic sensor stack body according to claim 36, wherein the magnetic layer and the first capping layer are formed on one of field regions while linearly moving the substrate at predetermined speed under a target parallel to junction wall faces of the magnetoresistive element,

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.

39. The method of forming a magnetic sensor stack body according to claim 30, wherein the layers are formed by ion beam deposition.

40. The method of forming a magnetic sensor stack body according to claim 33, further comprising a step of trimming the second seed layer and the underlayer on a thicker side on the junction wall face at an angle exceeding 60 degrees and less than 90 degrees from a normal of the substrate, before the step of forming the magnetic layer.

41. The method of forming a magnetic sensor stack body according to claim 32, wherein the steps are continuously performed under vacuum atmosphere of a continuous processor comprising:

a load lock module for loading/ejecting a substrate between vacuum space and atmosphere;

a conveyance chamber having a conveying mechanism;

an etching process chamber for performing an etching process;

a film forming chamber for forming the insulating layer; and

an oblique film formation chamber for performing an incidence control type sputtering process.

42. The method of forming a magnetic sensor stack body according to claim 41, wherein the continuous processor has a film forming chamber for forming a film by ion beam deposition or ionized physical vapor deposition.