JPH0973607A - Thin-film magnetic head and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-film magnetic head formed in such a manner that a free magnetization layer is surely magnetized by stabilizing the magnetization of a hard bias layer. SOLUTION: The hard bias layer 8 and a conductive layer 9 are first formed on a lower gap layer 1 at the time of producing the thin-film magnetic head. The conductive layer 9 and the hard bias layer 8 are removed in the part of a track width. The free magnetic layer 3 constituting a spin valve layer SV, nonmagnetic conductive layer 4, fixed magnetic layer 5, antiferromagnetic layer 6, etc., are successively laminated in this removed part. The film thickness of the hard bias layer 8 of this thin-film magnetic head is uniform and the magnetization of the hard bias layer 8 is stable in an X direction and since the hard bias layer 8 comes into contact with only the free magnetic layer 3, the sure magnetization of the free magnetic layer 3 in the X direction is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head for detecting a leakage magnetic field from a magnetic recording medium such as a hard disk by utilizing a magnetoresistive effect, and more particularly to magnetizing under the influence of the leakage magnetic field from the magnetic recording medium. The present invention relates to a spin-valve thin-film magnetic head having a free magnetic layer whose direction changes and a pinned magnetic layer whose magnetization direction is fixed and whose electric resistance changes depending on the relationship between the magnetization directions of both magnetic layers.

[0002]

2. Description of the Related Art FIG. 4 is a front view of a conventional spin valve thin film magnetic head. The traveling direction of a magnetic recording medium such as a hard disk with respect to this thin film magnetic head is the Z direction, and the direction of the leakage magnetic field (external magnetic field) from the magnetic recording medium is the Y direction. In the thin film magnetic head shown in FIG.
On the lower gap layer 1 formed of a non-magnetic material such as l ₂ O ₃ (aluminum oxide), a lower non-magnetic layer 2 such as Ta (tantalum), a free magnetic layer 3, a non-magnetic conductive layer 4, a fixed magnetic layer. Layer (Pined magnetic layer) 5, antiferromagnetic layer 6, Ta
A spin valve layer (SV) including a total of 6 layers of the upper non-magnetic layer 7 is formed.

The lower non-magnetic layer 2 is for adjusting the crystal orientation of the free magnetic layer 3 laminated thereon to lower the specific resistance of the free magnetic layer 3. Free magnetic layer 3
The fixed magnetic layer 5 and the fixed magnetic layer 5 are formed of a Ni-Fe (nickel-iron) alloy. The antiferromagnetic layer 6 is a bias layer that aligns the magnetization of the pinned magnetic layer 5 in the Y direction.
By the exchange anisotropic coupling at the film interface between the fixed magnetic layer 5 and
The pinned magnetic layer 5 is magnetized into a single magnetic domain in the Y direction (front side of the drawing). This antiferromagnetic layer 6 is, for example, Fe-M.
It is an n (iron-manganese) alloy, a Ni-Mn (nickel-manganese) alloy, or a Pt-Mn (platinum-manganese) alloy.

Hard bias layers 8 made of a Co-Pt (cobalt-platinum) -based material or the like are provided on both sides of the spin valve layer SV having the six-layer structure, and the hard bias layers 8 are formed at the contact cross section (a). Are in contact with all of the six layers constituting the spin valve layer SV. Further, on the hard bias layer 8, a conductive layer 9 made of a material having a small specific resistance such as Cu (copper), Ta, or Cr (chrome) is laminated.

In this spin-valve thin-film magnetic head, the hard bias layer 8 is permanently magnetized in the X direction, and the free magnetic layer 3 is magnetized in the X direction under the influence of this permanent magnetization. The fixed magnetic layer 5 is the antiferromagnetic layer 6
Is magnetized in the Y direction (front side of the drawing). A stationary current flows from the conductive layer 9 through the hard bias layer 8 to the spin valve layer SV having a six-layer structure in the X direction. When a magnetic field is applied from the magnetic recording medium in the Y direction, the direction of the magnetization of the free magnetic layer 3 changes from the X direction to the Y direction by this external magnetic field. The electric resistance value of the spin valve layer SV changes depending on the relationship between the magnetization direction of the pinned magnetic layer 5 and the magnetization direction of the free magnetic layer 3. Therefore, the leakage magnetic field from the magnetic recording medium can be detected by detecting the voltage drop of the steady current.

In the process of manufacturing the thin film magnetic head shown in FIG. 4, first, on the lower gap layer 1, the lower non-magnetic layer 2,
A spin valve layer SV including six layers of a free magnetic layer 3, a nonmagnetic conductive layer 4, a pinned magnetic layer 5, an antiferromagnetic layer 6 and an upper nonmagnetic layer 7 is continuously sputter-deposited. A resist material is applied onto the spin valve layer SV, and the spin valve layer S is subjected to an exposure process such as a deep UV method.
A resist layer is formed on a portion of the track width (Tw) above V. Next, etching such as ion milling is performed with the resist layer placed on the spin valve layer SV in the region where the resist layer is not formed. In this etching step, the spin valve layer SV is affected by the shape of the deep UV exposed resist layer.
The contact cross-section (a) is formed such that the skirt width increases toward the bottom of the layer.

Next, the hard bias layer 8 is formed by sputtering or the like while the resist layer is left on the spin valve layer SV. The hard bias layer 8 is formed into a shape as shown in FIG. 4 according to the shape of the resist layer,
The film thickness of the hard bias layer 8 in the contact cross section (a) becomes thinner toward the top of the spin valve layer SV. The film thickness is almost uniform except for the contact cross section (a). Further, a conductive layer 9 is formed on the hard bias layer 8.

[0008]

However, the thin film magnetic head having the structure shown in FIG. 4 has the following problems. (1) Since the hard bias layer 8 magnetizes the free magnetic layer 3 in the X direction, it is necessary that the magnetization directions of the hard bias layer 8 itself are aligned in the X direction. But,
In the contact cross section (a), the film thickness (dimension in the Z direction) of the hard bias layer 8 changes in a shape so as to ride on the spin valve layer SV. Therefore, it is difficult to align the magnetization direction in the hard bias layer 8 with the X direction. The reason is that in the portion where the film thickness of the hard bias layer 8 is changed, the direction and magnitude of the demagnetizing field when trying to magnetize in the X direction becomes irregular, and thus it is difficult to magnetize in the X direction. . Another reason is that since the hard bias layer 8 is in contact with all the materials of the six layers forming the spin valve layer SV, the magnetic field of the hard bias layer 8 in the contact cross section (a) depends on the material of each layer. This is because the characteristics are partially changed. For this reason, the magnetization of the hard bias layer 8 is less likely to be aligned in the X direction, the degree of single domain formation of the free magnetic layer 3 in the X direction is reduced, and Barkhausen noise is increased.

(2) The hard bias layer 8 is in contact with both sides of the fixed magnetic layer 5 and the antiferromagnetic layer 6. Therefore, the permanently biased hard bias layer 8 magnetically affects the pinned magnetic layer 5 and the antiferromagnetic layer 6 of the spin valve layer SV. Therefore, the magnetization direction of the pinned magnetic layer 5 is not fixed in the Y direction, and Barkhausen noise becomes large.

(3) In order to apply a sufficient magnetic field in the X direction from the hard bias layer 8 to the free magnetic layer 3,
The upper surface 8a of the hard bias layer 8 must be located above the upper surface of the free magnetic layer 3 in the figure. That is, the hard bias layer 8 needs to be formed with a considerably large film thickness, and the sputtering time becomes long.

The present invention solves the above-mentioned conventional problems, and stabilizes the magnetization of the hard bias layer so that the free magnetic layer can be reliably magnetized by the hard bias layer, and It is intended to provide a manufacturing method thereof.

[0012]

A spin valve thin film magnetic head according to the present invention comprises a free magnetic layer which is sequentially stacked,
A non-magnetic layer, a pinned magnetic layer, hard bias layers provided on both sides of the free magnetic layer to magnetize the free magnetic layer in one direction, and stacked on the pinned magnetic layer to form the pinned magnetic layer. A bias layer that magnetizes in a direction intersecting with the magnetization direction of the free magnetic layer, and only the free magnetic layer is in contact with the contact cross section of the hard bias layers located on both sides. is there.

Further, the contact cross section of the hard bias layer is inclined in a direction in which the distance between the contact cross sections increases toward the top of the layer, and the hard bias layer has a contact cross section and a portion other than the contact cross section. And the film thickness is almost uniform.

In the method of manufacturing the thin film magnetic head, the hard bias layer and the conductive layer are first laminated, the conductive layer and the hard bias layer are partially removed, and the removed portion is free magnetic layer and nonmagnetic layer. A pinned magnetic layer and a bias layer that magnetizes the pinned magnetic layer in a direction intersecting the magnetization direction of the free magnetic layer are stacked, and only the free magnetic layer is in contact with the hard bias layer.

In the spin valve thin film magnetic head of the present invention, since the hard bias layer is in contact with only the free magnetic layer in the contact cross section, the free magnetic layer can be reliably magnetized by the hard bias layer. Also,
The magnetic field of the hard bias layer does not affect the fixed magnetic layer other than the free magnetic layer.

Further, if the hard bias layer has a uniform film thickness, there is no variation in the magnitude and direction of the demagnetizing field, and the magnetization direction in the hard bias layer can be aligned in one direction. Further, a sufficient magnetic field can be applied to the free magnetic layer without increasing the thickness of the hard bias layer more than necessary.

Further, in the method of manufacturing the thin film magnetic head of the present invention, since the hard bias layer is laminated before the formation of the spin valve layer composed of the free magnetic layer and the pinned magnetic layer, the hard bias layer has a uniform film thickness. Can be formed with.
By providing a base film made of Cr (chrome) under the hard bias layer, the magnetic characteristics of the hard bias layer can be improved. When a part of the hard bias layer is removed and a free magnetic layer, a nonmagnetic layer, and a pinned magnetic layer are sequentially stacked on the removed part, only the free magnetic layer is formed in the contact cross section of the hard bias layer. It comes into contact.

[0018]

FIG. 1 is a front view showing a spin-valve type thin film magnetic head of the present invention. In this thin film magnetic head, the Z direction is the moving direction of the magnetic recording medium, and the Y direction is the direction of the leakage magnetic field (external magnetic field) from the magnetic recording medium. A lower nonmagnetic layer 2 made of Ta (tantalum) or the like is laminated on a lower gap layer 1 made of a nonmagnetic material such as Al ₂ O ₃ (aluminum oxide). When the free magnetic layer 3 is stacked on the lower non-magnetic layer 2 made of Ta, the crystal orientation of the free magnetic layer 3 is adjusted,
The specific resistance of the free magnetic layer 3 becomes small.

In the portion having the track width Tw, the free magnetic layer 3, the nonmagnetic conductive layer 4, the pinned magnetic layer 5, the antiferromagnetic layer 6, and the upper nonmagnetic layer 7 are arranged in this order from the bottom on the lower nonmagnetic layer 2. The spin valve layer SV having a five-layer structure is formed by stacking layers. The free magnetic layer 3 and the pinned magnetic layer 5 are made of Ni-Fe.
(Nickel-iron) based alloy, non-magnetic conductive layer 4 is Cu
(Copper), the antiferromagnetic layer 6 is a Fe-Mn (iron-manganese) alloy, a Ni-Mn (nickel-manganese) alloy, or Pt.
-Mn (platinum-manganese) alloy, the upper non-magnetic layer 7 is Ta
It is formed by. The antiferromagnetic layer 6 is the fixed magnetic layer 5
Is a bias layer for magnetizing the magnetic field into a single magnetic domain in the Y direction (front side of the paper), and the pinned magnetic layer 5 becomes Y by the exchange anisotropic coupling at the film interface between the antiferromagnetic layer 6 and the pinned magnetic layer 5. Magnetized in the direction.

On both sides of the track width Tw, a base film 10 made of Cr (chrome) is laminated on the lower nonmagnetic layer 2 in close contact with each other. This Cr underlayer film 10 is for improving the magnetic characteristics of the hard bias layer 8 laminated thereon. Co-P is formed on the base film 10.
hard bias layer 8 formed of t (cobalt-platinum) or the like, conductive layer 9 of Cu, Cr, W (tungsten), or the like.
Are sequentially stacked. The contact cross section (b) of the hard bias layer 8 and the conductive layer 9 is inclined in a direction in which the distance between the contact cross sections increases toward the top of the layers.
In this contact section (b), the hard bias layer 8 is in contact with only the free magnetic layer 3. Therefore, unlike the conventional case, an unnecessary magnetic field is not applied from the hard bias layer 8 to the pinned magnetic layer 5, and since the hard bias layer 8 is in contact with only the free magnetic layer 3, the conventional magnetic field shown in FIG. As in the example, the hard bias layer does not contact the plurality of layers to change the magnetic characteristics due to the contact material, and the magnetic characteristics of the hard bias layer 8 are stabilized.

The hard bias layer 8 and the conductive layer 9 are formed as flat films parallel to each other on the lower gap layer 1, and the hard bias layer 8 has a contact cross section (b).
The film thickness is almost uniform except the contact cross section. Therefore, in the contact cross section (b), the magnitude and direction of the demagnetizing field of the hard bias layer 8 are aligned, and the hard bias layer 8 becomes X-shaped.
It becomes easy to magnetize in the direction.

In the thin-film magnetic head shown in FIG. 1, the hard bias layer 8 has a uniform film thickness, and the direction of permanent magnetization of the hard bias layer 8 is aligned in the X direction.
Contact only the free magnetic layer 3. Therefore, the magnetization direction of the free magnetic layer 3 is easily aligned in the X direction by the hard bias layer 8. The magnetization of the pinned magnetic layer 5 is oriented in the Y direction (front side of the drawing) by exchange anisotropic coupling with the antiferromagnetic layer 6. The pinned magnetic layer 5 is not affected by the hard bias layer 8, and the magnetization direction of the pinned magnetic layer 5 is stabilized in the Y direction. A steady current is applied from the conductive layer 9 through the hard bias layer 8 to each layer forming the spin valve layer SV in the X direction. When an external magnetic field is applied in the Y direction, the magnetization direction of the free magnetic layer 3 changes, and the electric resistance value changes depending on the relationship between the magnetization direction of the free magnetic layer 3 and the magnetization direction of the pinned magnetic layer 5. The change in the electric resistance value is detected by the voltage drop, and the leakage magnetic field from the magnetic recording medium is read. As described above, since the magnetization direction of the free magnetic layer 3 and the magnetization direction of the fixed magnetic layer 5 are stable, Barkhausen noise hardly occurs in the detection output, and a highly accurate detection output can be obtained.

2A to 2F show a method of manufacturing the thin film magnetic head shown in FIG. 1 in order of steps. FIG.
As shown in (A), first, the hard bias layer 8 and the conductive layer 9 are sequentially formed on the lower gap layer 1. Although not shown, the lower nonmagnetic layer 2 is formed on the lower gap layer 1, and the base film 10 is formed under the hard bias layer 8. By depositing the hard bias layer 8 before depositing the spin valve layer SV, the hard bias layer 8 having a uniform and flat film thickness can be formed.

Next, a resist material is applied on the conductive layer 9 by spin coating or the like. Then, the resist material is pre-baked, exposed using a mask, developed, and post-baked to form a resist layer 11. By this process,
As shown in FIG. 2B, the resist layer 11 is formed on both sides having a predetermined track width Tw. Resist layer 11
In a state where the resist layer 11 is formed, etching is performed by ion milling or the like, and the conductive layer 9 and the hard bias layer 8 in a region (within the track width Tw) where the resist layer 11 is not formed.
Is removed. After the above etching is completed, the resist layer 1
The state in which 1 is removed is shown in FIG. The portion where the conductive layer 9 and the hard bias layer 8 are removed becomes a recess, and the bottom width dimension of this recess becomes the track width Tw.

Next, as shown in FIG. 2D, five layers from the free magnetic layer 3 constituting the spin valve layer SV to the upper nonmagnetic layer 7 are sequentially formed by sputtering. The spin valve layer SV is formed on the lower gap layer 1 and the lower nonmagnetic layer 2 in the portion having the track width Tw, and is formed on the conductive layer 9 in the other regions.

As shown in FIG. 2 (E), a resist layer 12 is formed on the entire upper surface of the spin valve layer SV, and the resist layer 12 fills the concave portion of the track width Tw.
Then, the resist layer 12 formed in the other portions is removed by etching back or the like, leaving only the resist layer 12 formed in the recesses. As a result, FIG.
As shown in (F), the concave portions are filled with the resist layer 12, and the surface irregularities are almost eliminated. Etching such as ion milling is performed on the spin valve layer S in the region where the resist layer 12 is not formed (portion other than Tw).
Remove V. After that, the resist layer 12 in the recess is removed to form the thin film magnetic head shown in FIG.

In the manufacturing method shown in FIG. 2, since the hard bias layer 8 is formed before the spin valve layer SV is formed, the hard bias layer 8 has a uniform film thickness. Further, the Cr underlayer film 10 can be formed under the hard bias layer 8, and the magnetic characteristics of the hard bias layer 8 are improved. Further, since the concave portion is formed in the hard bias layer 8 and the conductive layer 9 and the spin valve layer SV is formed in the concave portion, the free magnetic layer 3 as the lowermost layer of the spin valve layer SV is formed as the hard bias layer 8. It can be surely brought into close contact.

FIG. 3 shows a thin film magnetic head having another structure. In the thin-film magnetic head shown in FIG. 3, the spin valve layer SV is composed of a total of four layers including the free magnetic layer 3, the nonmagnetic conductive layer 4, the pinned magnetic layer 5 and the bias layer 13.
The bias layer 13 is for magnetizing the pinned magnetic layer 5 toward the front side of the drawing, and as the bias layer 13, α
-Fe ₂ O ₃ (iron oxide) is used. α-Fe ₂ O ₃
Not only magnetizes the pinned magnetic layer 5 in the Y direction by exchange anisotropic coupling with the pinned magnetic layer 5 of Ni—Fe alloy,
Coercive force Hc of the pinned magnetic layer 5 that is in close contact with α-Fe ₂ O ₃
And allows the pinned magnetic layer 5 to be permanently magnetized in the Y direction. When α-Fe ₂ O ₃ is used as the bias layer 13 as described above, the magnetization of the pinned magnetic layer 5 is stabilized and Barkhausen noise can be reduced.

Further, since α-Fe ₂ O ₃ is a material having excellent corrosion resistance, it is not necessary to form the upper nonmagnetic layer 7 of Ta on the uppermost layer as shown in FIG. The time for forming the layer SV is also shortened.

[0030]

As described above, in the present invention, since the hard bias layer is in contact with only the free magnetic layer, the hard bias layer does not give an unnecessary magnetic field to the other layers, and only the free magnetic layer is secured. Can be made into a single magnetic domain.

Further, if the thickness of the hard bias layer is made uniform, the magnetization of the hard bias layer can be aligned in one direction, and as a result, the magnetization direction of the free magnetic layer can be stabilized.

Further, in the method of manufacturing the thin film magnetic head of the present invention, the hard bias layer can be formed in a uniform thickness by forming the hard bias layer first and then forming the free magnetic layer and the like. .

[Brief description of drawings]

FIG. 1 is a front view of a thin film magnetic head of the present invention,

2A to 2F are front views showing a method of manufacturing the thin film magnetic head of the present invention in the order of steps,

FIG. 3 is a front view showing another structure of the thin film magnetic head of the present invention,

FIG. 4 is a front view showing the structure of a conventional spin valve thin film magnetic head;

[Explanation of symbols]

 3 Free Magnetic Layer 4 Non-Magnetic Conductive Layer 5 Fixed Magnetic Layer 6 Antiferromagnetic Layer 8 Hard Bias Layer 9 Conductive Layer 10 Underlayer 13 Bias Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Watanabe 1-7 Yukiya Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd.

Claims (4)

[Claims] 1. A free magnetic layer, a non-magnetic layer, and a pinned magnetic layer which are sequentially stacked, hard bias layers which are provided on both sides of the free magnetic layer and magnetize the free magnetic layer in one direction, and the pinned magnetic layer. A bias layer laminated on the magnetic layer to magnetize the pinned magnetic layer in a direction intersecting with the magnetization direction of the free magnetic layer, and the free magnetic layer is provided in a contact cross section of the hard bias layers located on both sides. A spin-valve thin-film magnetic head characterized in that only the contacts are in contact. 2. The thin film magnetic head according to claim 1, wherein the contact cross section of the hard bias layer is inclined in a direction in which the distance between the contact cross sections increases toward the top of the layer. 3. The thin film magnetic head according to claim 1, wherein the hard bias layer has a substantially uniform film thickness in a contact cross section and a portion other than the contact cross section. 4. A hard bias layer and a conductive layer are first laminated, a part of the conductive layer and the hard bias layer is removed, and a free magnetic layer, a non-magnetic layer, a pinned magnetic layer and a pinned portion are formed in the removed portion. A spin-valve thin-film magnetic head characterized in that a magnetic layer is laminated with a bias layer that magnetizes in a direction crossing the magnetization direction of the free magnetic layer, and only the free magnetic layer is brought into contact with the hard bias layer at this time. Production method.