JPH0981916A - Magnetoresistance effect type head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely set track width and to reduce unevenness in reproduction output, element resistance and Barkhausen noise by arranging a magnetoresistance effect element layer, a structure for applying a high bias magnetic field and electrodes on an electrically conductive underlayer. SOLUTION: A lower shield 1 of NiFe is formed by plating on a ceramic nonmagnetic substrate and is patterned by ion milling. A lower gap 2 of Al2 O3 and a Cr film as an electrically conductive underlayer 3 are successively formed by sputtering on the patterned shield 1. A CoCrMo layer as a soft magnetic auxiliary bias layer, a Ta layer as a middle layer and an MR element layer 4 made of an NiFe film as a ferromagnetic MR layer are then successively formed by sputtering and patterned by ion milling. Permanent magnet layers 5 each made of a CoCrPt film and electrode layers 6 of Au are formed by sputtering on both sides of the resultant patterned magnetic film and an upper gap 7 of Al2 O3 is formed by sputtering. An upper shield 8 of NiFe is formed by plating on the gap 7 and patterned by ion milling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head (hereinafter referred to as an MR element) having a magnetoresistive element (hereinafter referred to as an MR element) for reading out magnetic information written in a magnetic recording medium by utilizing a magnetoresistive effect. , MR head).

[0002]

2. Description of the Related Art Since an MR head can obtain a high output and the output does not depend on the relative speed between the head and a recording medium, research and development as a reproducing head of a small-sized and high-density magnetic recording device has been actively conducted. There is. To use the MR head as a signal reproducing head for high track density magnetic recording, M
It is necessary to accurately determine the track width of the R head. In order to suppress Barkhausen noise, which is particularly noticeable when the track width is narrow, a structure for realizing a single magnetic domain of the MR element is added, and a bias magnetic field (hereinafter referred to as a longitudinal bias magnetic field) in the sense current direction is added. ) Need to be added.

FIG. 4 is a cross-sectional view of a conventional MR head as viewed from the disk facing surface.

The MR head shown in FIG. 4 is disclosed in Japanese Patent Laid-Open No. 3-12531.
The track width is defined by the width of the MR element itself. In this MR head, the longitudinal bias magnetic field is applied by the permanent magnet film formed on both sides of the MR element. Next, this conventional M
A method of forming the R head will be described.

As shown in FIG. 4, a lower shield 1 and a lower gap 2 are formed in the same manner as in Example 1 described later.

Next, an MR element layer 4 consisting of CoZrMo having a thickness of 20 nm as a soft magnetic auxiliary bias layer, a Ta film having a thickness of 10 nm as a separation layer, and a NiFe film having a thickness of 15 nm serving as a magnetoresistive effect layer is formed by a sputtering method. .

The MR element layer 4 is patterned with a width of 2 μm by ion milling after applying a stencil type resist. At this time, the MR element layer 4 is processed into a taper of about 10 degrees in order to ensure electrical connection with the permanent magnet layer to be formed next.

Thereafter, on both sides of the patterned MR element layer, a Cr film having a thickness of 10 nm is formed by the sputtering method as a base (not shown) for orienting the permanent magnet film to be formed next in the plane. Be filmed.

Further, the permanent magnet layer 5 made of CoCrPt film and having a thickness of 20 nm and the electrode layer 6 made of Au and having a thickness of 0.2 μm are scattered and the resist is removed.

After that, the upper gap 7 and the upper shield 8 are formed by the same process as in the first embodiment.

[0011]

However, this conventional M
In the configuration of the R head, the MR element layer 4 and the permanent magnet film 5
Is required to be magnetically and electrically coupled to M
There is a problem in that the R element layer 4 needs to be processed into a gentle taper, which makes the process difficult. Further, since the accuracy of the track width depends on the accuracy of the gentle taper processing, there is a problem that the yield is deteriorated in manufacturing a narrow track head. There is also a problem that the element resistance varies depending on the contact state between the MR element layer 4 and the permanent magnet film 5 and the presence or absence of Barkhausen noise varies.

The present invention has been made in view of the above points, and provides a magnetoresistive head (MR head) capable of accurately determining a track width and having little variations in reproduction output, element resistance, and Barkhausen noise. The purpose is to provide.

[0013]

In order to solve the above problems, in the MR head of the present invention, an MR element, a structure for applying a longitudinal bias magnetic field and an electrode are formed on a conductive underlayer. Further, in the first configuration, the MR element is individually patterned, and structures for applying a longitudinal bias magnetic field are arranged on both sides of the MR element while maintaining magnetic coupling. In the second configuration, the MR element and the structure for applying the longitudinal bias magnetic field are patterned in the same shape, and are arranged on both sides of the MR element directly or at a certain interval.

In any structure, a permanent magnet film can be used as a structure for applying a longitudinal bias magnetic field. In this case, as the conductive underlayer, a material that becomes the underlayer of the permanent magnet film can be used. The MR element has a structure including a ferromagnetic magnetoresistive film and a structure for applying a lateral bias magnetic field, or a first ferromagnetic layer pinned by an antiferromagnetic layer, a conductive intermediate layer, and a second strong layer. It is possible to adopt a configuration including a magnetic layer.

In the second structure, the MR element and the structure for applying the longitudinal bias magnetic field are ferromagnetic magnetoresistive films,
It consists of a permanent magnet film and a film for magnetically separating the ferromagnetic magnetoresistive effect film and the permanent magnet film, and applies both a transverse bias magnetic field and a longitudinal bias magnetic field to the ferromagnetic magnetoresistive effect film by the permanent magnet film. be able to. An antiferromagnetic layer for pinning the magnetic layer can also be used as the conductive underlayer. In this case, a structure including a first ferromagnetic layer, a conductive intermediate layer, and a second ferromagnetic layer as an MR element, or a soft magnetic film combined with an antiferromagnetic layer as a structure for applying a longitudinal bias magnetic field Can be used.

In the MR head of the present invention, the electrical coupling is ensured by the conductive underlayer, so the electrical coupling between the MR element and the structure for applying the longitudinal bias magnetic field such as the electrode or the permanent magnet film is ensured. The head structure can be designed without consideration. Therefore, it is not necessary to process the MR element into a taper with a gentle angle, and the track width can be accurately determined. Further, variations in the resistance of the element are reduced because the current path through the underlayer is secured.
When a permanent magnet film is used as a structure for applying a longitudinal bias magnetic field and a material that forms the base of the permanent magnet is used as a conductive base layer, the permanent magnet has a magnetization direction that is in the same plane as the MR element, and therefore stable. The generated longitudinal bias can be supplied to the MR element.

In the MR head of the present invention, the reproduction output is lowered by the current shunting effect of the conductive underlayer as compared with the case without the underlayer. This decrease in playback output is due to MR
Power of the element - when the (resistance × current ²⁾ is constant, Vu / Vm = (1 + Rm / Ru) -3/2 and (2) expressed. Here, Ru and Rm are sheet resistances of the underlayer and the MR element, and Vu and Vm are outputs with and without the underlayer. Therefore, by selecting the sheet resistance of the underlayer according to the output reduction allowed in the magnetic recording system, it was possible to provide an MR head that is less affected by the reproduction output reduction.

[0018]

DETAILED DESCRIPTION OF THE INVENTION An MR head according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an MR head according to a first embodiment of the present invention as viewed from the disk facing surface.

As shown in the figure, a lower shield 1 using NiFe having a thickness of 2 μm is formed on a ceramic non-magnetic substrate (not shown) by a plating method, and patterned into a width of 60 μm by ion milling. . On top of that, a thickness of 0.2μ
The lower gap 2 using m ₂ of Al ₂ O ₃ is formed by the sputtering method.

Further, the conductive underlayer 3 has a thickness of 10 n.
A Cr film of m is formed by the sputtering method. This Cr
The film also serves as a base for in-plane orientation of the CoCrPt film to be formed later.

Next, an MR comprising a 20 nm thick CoZrMo as a soft magnetic auxiliary bias layer, a 10 nm Ta film as an intermediate layer, and a 15 nm NiFe film as a ferromagnetic magnetoresistive layer.
The element layer 4 is formed by the sputtering method.

The MR element layer 4 is patterned with a width of 2 μm by ion milling after applying a stencil type resist.

Then, on both sides of the patterned magnetic film
50 nm thick permanent magnet layer 5 made of CoCrPt film and Au
The electrode layer 6 of 0.2 μm composed of
The resist is removed.

Next, a 0.24 μm-thick Al ₂ O ₃ film is formed on this.
Is used to form the upper gap 7 by sputtering.

An upper shield 8 made of NiFe having a thickness of 2 μm is formed thereon by a plating method and patterned into a width of 60 μm by ion milling.

FIG. 2 is a sectional view of the MR head according to the second embodiment of the present invention as viewed from the disk facing surface.

As shown in the figure, a lower shield 1 using NiFe having a thickness of 2 μm is formed on a ceramic non-magnetic substrate (not shown) by a plating method, and patterned into a width of 60 μm by ion milling. . On top of that, a thickness of 0.2μ
The lower gap 2 using m ₂ of Al ₂ O ₃ is formed by the sputtering method.

Further, the conductive underlayer 3 has a thickness of 10 n.
A Cr film of m is formed.

Next, as a permanent magnet film 5, Co having a thickness of 20 nm is used.
A CrPt film is formed by the sputtering method. Since the permanent magnet film 5 is magnetized at 45 degrees with respect to the track width direction, both the lateral bias magnetic field and the vertical bias magnetic field are applied to the magnetoresistive effect film.

Next, a Ti film 10 nm as an intermediate layer and a NiFe film 15 nm as a ferromagnetic magnetoresistive effect layer 10 are formed by a sputtering method. Then, the permanent magnet film 5, the intermediate layer 9, and the ferromagnetic magnetoresistive layer 10 are patterned into a width of 2 μm by ion milling after applying a stencil type resist.

Then, on both sides of the patterned magnetic film,
The 0.2 μm electrode layer 6 made of Au is scattered and the resist is removed.

Next, a 0.24 μm-thick Al ₂ O ₃ film is formed on this.
Is used to form the upper gap 7 by sputtering.

Then, an upper shield 8 made of NiFe having a thickness of 2 μm is formed thereon by a plating method and patterned into a width of 60 μm by ion milling.

FIG. 3 is a sectional view of the MR head according to the third embodiment of the present invention as viewed from the disk facing surface.

As shown in the drawing, a lower shield 1 using NiFe having a thickness of 2 μm is formed on a ceramic non-magnetic substrate (not shown) by a plating method, and patterned into a width of 60 μm by ion milling. . On top of that, a thickness of 0.2μ
The lower gap 2 using m ₂ of Al ₂ O ₃ is formed by the sputtering method.

Further, the conductive underlayer 3 has a thickness of 10 n.
A NiMn film of m is formed by the sputtering method.

Next, the thickness of the first ferromagnetic layer 11 is 1
0 nm NiFe, 5 nm thick Cu layer as the intermediate layer 12,
NiFe having a thickness of 10 nm is formed as the second ferromagnetic layer 13 by a sputtering method. Here, the first ferromagnetic layer 11 is pinned in the MR height direction by the underlying NiMn layer.

Then, after applying a stencil type resist, the first ferromagnetic layer 11, the intermediate layer 12 and the second ferromagnetic layer 13 are patterned into a width of 2 μm by ion milling. Furthermore, a Cr film having a thickness of 10 nm is used as a base layer (not shown) of the permanent magnet film, a CoCrPt film having a thickness of 10 nm is used as a permanent magnet film 5 for applying a lateral bias, and an electrode layer having a thickness of 0.2 μm made of Au. 6 is sluttered and the resist is removed.

Next, a 0.24 μm-thick Al ₂ O ₃ film is formed on top of this.
Is used to form the upper gap 7 by sputtering.

An upper shield 8 made of NiFe having a thickness of 2 μm is formed thereon by a plating method and patterned into a width of 60 μm by ion milling.

[0042]

EXAMPLES In Examples 1 and 2, a Cr layer was used as the underlayer of the conductive layer, which is also effective as the underlayer of the permanent magnet. Further, in Example 3, as the conductive underlayer,
NiMn, which is an antiferromagnetic film, was used. However, if it is a conductive film, another film such as Ta, Ti,
Needless to say, Cu or the like can be used.

However, in order to avoid a decrease in reproduction output,
The sheet resistance of the underlayer needs to be larger than that determined by the equation (2). When the sheet resistance of the MR element is 15Ω and the allowable output reduction is 70%, the sheet resistance of the underlayer needs to be 56Ω or more. If this is converted into a film thickness using the relative resistance of the name material, the upper limit of the film thickness of the underlayer is as shown in Table 1.

[0044]

[Table 1] Upper limit of thickness of underlayer (output decrease 7
0%) Material ratio Low resistance (μΩcm) Film thickness upper limit (nm) Cr 60 10.7 NiMn 70 12.5 Ta 200 35.8 Ti 50 8.9 Cu 20 3.6 In Example 2, electrodes and MR element Are in contact,
It does not affect the reproduction characteristics even if they are not in contact. However, in this case, a portion where the current flows only in the base layer is generated, so that the element resistance is increased. In Examples 1 and 3, the permanent magnet film and the MR element need not be in electrical contact with each other, but must be in magnetic contact with each other. In the examples, the evaluation was performed by recording and reproducing with separate heads, but it goes without saying that the present invention can be applied to a magnetic head in which a recording head is laminated on an upper shield.

In the embodiment, a permanent magnet film is used as a structure for applying a longitudinal bias magnetic field, but this can be replaced with a soft magnetic material pinned with an antiferromagnetic material.

[0046]

The reproducing output and the off-track characteristics were measured by processing 100 sliders each of the MR heads of the embodiment of the present invention and the conventional example produced as described above. Coercive force of 2000 Oe and saturation magnetic flux density of 500
A 0 Gauss, 30 nm thick CoCrPt thin film longitudinal medium was used, and the flying height was 0.08 μm. Recording was performed by the same thin film head. Playback output and execution track width in Table 2 (defined as half-value of off-track characteristics)
The measurement results of the average value and the deviation σ of are shown.

[0047]

[Table 2] In Table 2, in each of the heads of the examples, there is little deviation between the reproduction output and the execution track width, and the MR ratio is high.
The head can be produced. On the other hand, in the conventional example, there are large variations in reproduction output and effective track width. It is considered that this reflects the variation in the shape and resistance value of the contact portion between the permanent magnet layer and the MR element. Further, Barkhausen noise was not observed at all in the head of the example, whereas it was observed at a rate of 10% in the head of the conventional example.

As described above, in the MR head of the present invention, since the MR element, the structure for applying the longitudinal bias magnetic field and the electrode are arranged on the conductive underlayer, the MR element and the electrode or the longitudinal bias magnetic field are applied. A current can be passed through the MR element regardless of whether the structure for applying is in electrical contact. Therefore, the structure between the MR element and the electrode or the structure for applying the longitudinal bias magnetic field can be simplified, and an MR head with a high yield can be produced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an MR head according to a first embodiment of the present invention as viewed from a disk facing surface.

FIG. 2 is a cross-sectional view of an MR head according to a second embodiment of the present invention as viewed from the disk facing surface.

FIG. 3 is a sectional view of an MR head according to a third embodiment of the present invention as viewed from the disk facing surface.

FIG. 4 is a cross-sectional view of a conventional MR head as viewed from the disk facing surface.

[Explanation of symbols]

 1 Lower Shield 2 Lower Gap 3 Underlayer 4 MR Element Layer 5 Permanent Magnet Film 6 Electrode Layer 7 Upper Gap 8 Upper Shield 9 Intermediate Layer 10 Ferromagnetic Magnetoresistive Layer 11 First Ferromagnetic Layer 12 Intermediate Layer 13 Second Ferromagnetic layer 14 Underlayer (antiferromagnetic layer)

Claims (12)

[Claims] 1. A magnetoresistive head comprising a magnetoresistive effect element layer, a structure for applying a longitudinal bias magnetic field and electrodes, wherein the magnetoresistive effect element layer, a structure for applying a longitudinal bias magnetic field and an electrode are conductive. A magnetoresistive head, wherein the magnetoresistive head is arranged on the underlayer of. 2. The magnetoresistive head according to claim 1, wherein a structure for applying a longitudinal bias magnetic field is arranged on both sides of the magnetoresistive effect element while maintaining magnetic coupling. 3. The magnetoresistive element layer and the structure for applying a longitudinal bias magnetic field are patterned in the same shape, and electrodes are arranged on both sides of the magnetoresistive element layer in contact or with a space. Magnetoresistive head. 4. The magnetoresistive head according to claim 1, wherein a structure for applying a longitudinal bias magnetic field is mainly composed of a permanent magnet film. 5. The magnetoresistive head according to claim 4, wherein a material serving as a base of the permanent magnet film is used as the conductive base layer. 6. A structure for applying a longitudinal bias magnetic field to a magnetoresistive effect element layer, and a structure for magnetically separating a ferromagnetic magnetoresistive effect film, a permanent magnet film, and a ferromagnetic magnetoresistive effect film from a permanent magnet film. The magnetoresistive head according to claim 3, wherein the magnetoresistive head is made of a film, and a transverse bias magnetic field and a longitudinal bias magnetic field are applied to the ferromagnetic magnetoresistive film by the permanent magnet film. 7. The magnetoresistive head according to claim 1, wherein the magnetoresistive element layer comprises a ferromagnetic magnetoresistive film and a structure for applying a lateral bias magnetic field. 8. A first ferromagnetic layer, a magnetoresistive element pinned by an antiferromagnetic layer, a conductive intermediate layer, and a second ferromagnetic layer.
6. The magnetoresistive head according to claim 1, comprising the ferromagnetic layer. 9. The magnetoresistive head according to claim 1, wherein an antiferromagnetic film is used as the conductive underlayer. 10. The magnetoresistive effect element is a first ferromagnetic layer,
The magnetoresistive head according to claim 9, comprising a conductive intermediate layer and a second ferromagnetic layer. 11. The magnetoresistive head according to claim 9, wherein the structure for applying a longitudinal bias magnetic field is composed of a soft magnetic film combined with an antiferromagnetic layer. 12. The sheet resistance of the conductive underlayer is Ru,
When the sheet resistance of the MR element is Rm and the outputs with and without the underlayer are Vu and Vm, the resistance of the conductive underlayer is Ru> Rm / ((Vu / Vm) ^-2/3 -1) The magnetoresistive head according to any one of claims 1 to 11, which is (1).