JPH07244821A - Manufacture of resistance effect type head - Google Patents

Abstract

PURPOSE:To effectively reduce the generation of Barkhausen noise caused by magnetic wall move by effectively setting the inside of a magnetic resistance effect element layer to a single magnetic domain state. CONSTITUTION:Two positions, namely both edge parts in the longitudinal direction, which are separated properly in the direction of axis of easy magnetization of a magnetic resistance effect element layer 1 formed on a substrate 4, are thinned by a specific amount, thus forming thinned parts 10, 10 where the oxide film on the surface of the magnetic resistance effect element layer 1 is eliminated. Antiferromagnetism body layers 5, 5 consisting of an antiferromagnetism body are laminated on the surface of thinned parts 10, 10 by a process which continues to the formation process and a single magnetic domain state is realized inside the magnetic resistance effect element layer 1 which is sandwiched by the thinned parts 10, 10 by the operation of a stable exchange coupling magnetic field generated in the interface between the thinned parts 10, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetoresistive head for reproducing recorded information on a magnetic recording medium such as a magnetic disk or a magnetic tape by utilizing the magnetoresistive effect.

[0002]

2. Description of the Related Art In a magnetic disk device which is widely used as an auxiliary storage device for a computer, a demand for miniaturization and high density recording has been increasing in recent years, and in order to meet this demand, a magnetic disk used as a recording medium. On the side, the recording track width and the line recording width tend to become narrower. Along with this, it is becoming difficult to reliably reproduce recorded information with an induction type head that utilizes magnetic induction electromotive force, and as a promising reproducing means to replace the induction type, the electric resistance of a ferromagnetic material is strong and weak in the peripheral magnetic field. A magnetoresistive head that utilizes the property of increasing / decreasing in accordance with the above, that is, the magnetoresistive effect has attracted attention.

FIG. 7 is a perspective view of a conventional magnetoresistive head. The magnetoresistive head comprises a rectangular magnetoresistive element layer 1 and a pair of electrode layers 2 and 2 which are in contact with both sides of the magnetoresistive element layer 1 in the longitudinal direction which is the direction of the easy axis of magnetization. Both of these layers are laminated on the end face of the substrate 4 together with the protective layer 3 made of an insulating material and covering the whole.

The substrate 4 constitutes a slider that floats above the recording surface of the magnetic recording medium with a slight gap and moves relative to the recording surface in a predetermined direction. One long side of No. 1 is exposed so as to face the recording surface on the rear side in the relative movement direction of the substrate 4 as the slider. A magnetic shield layer for shielding magnetic noise from the outside is provided on both sides of the magnetoresistive effect element layer 1 and the conductive layers 2 and 2 in the thickness direction to ensure electrical and magnetic insulation. Although they are laminated via the respective different insulating layers, they are not shown in FIG. 7.

Thus, in the magnetoresistive element layer 1, a change in electric resistance occurs due to the relative movement of the recording surface with respect to the substrate 4 due to the action of the magnetic field in each part of the recording surface, and this change occurs in the electrode. The recorded information is taken out as an output between the layers 2 and 2 to reproduce the recorded information. At this time, a change in the electric resistance of the magnetoresistive effect element layer 1 occurs in response to the magnetic field itself on the recording surface and does not depend on the relative speed of the recording surface. It can cope with the decrease in speed. On the other hand, the reproducing sensitivity can be improved and the line recording width can be narrowed by making the magnetoresistive effect element layer 1 thin enough and setting the original electric resistance large. As described above, the magnetoresistive head has many advantages for coping with miniaturization and high recording density of the magnetic recording medium.

[0006]

However, the magnetoresistive effect element layer 1 which is the main part of the magnetoresistive effect type head as described above generally has non-uniformity due to incomplete film formation. Therefore, in the magnetoresistive effect element layer 1, since the domain wall that separates the magnetic domain is moved by the action of the magnetic field on the recording surface, during the reproduction signal of the magnetoresistive head,
There is an inconvenience that noise due to the movement of the domain wall, so-called Barkhausen noise, is mixed, and it is an important subject to reduce the Barkhausen noise when the magnetoresistive head is put to practical use.

As an effective method for reducing Barkhausen noise, C. Tsang et al.
s on Magnetics, Vol.25, No.5, 1989, pp.3692-3694 "
There is a method proposed in. This is because an antiferromagnetic material layer made of an antiferromagnetic material such as FeMn is laminated on the portion where the internal magnetic pole of the magnetoresistive effect element layer 1 is generated, that is, both ends in the direction of the easy magnetization axis (longitudinal direction). It is a method of forming. In this case, due to the action of the exchange coupling magnetic field generated at the interface between the magnetoresistive effect element layer 1 and the antiferromagnetic material layer,
The inside of the magnetoresistive effect element layer 1 becomes a single magnetic domain, and the generation of Barkhausen noise accompanying the movement of the domain wall can be significantly reduced.

However, when an antiferromagnetic material layer is laminated on the magnetoresistive effect element layer 1, the surface of the magnetoresistive effect element layer 1 exposed to the air during this time is oxidized and the interface between the two layers is oxidized. Since the film is interposed, the exchange coupling magnetic field is not stably generated at such an interface, and there is a problem that the effect of reducing Barkhausen noise cannot be sufficiently obtained.

Therefore, in Japanese Unexamined Patent Publication (Kokai) No. 5-54337, after the magnetoresistive effect element layer 1 is formed, the magnetoresistive effect element layer 1 is covered with a mask material except both ends thereof, and in this state, the magnetoresistive effect element layer 1 is made of a soft magnetic material. A method has been proposed in which a soft magnetic layer and an antiferromagnetic material layer made of an antiferromagnetic material are continuously formed, and then the mask material is removed. FIG. 8 is a perspective view of a magnetoresistive head obtained by the above method.

As shown in the drawing, the soft magnetic layer 6 and the antiferromagnetic material layer are provided outside the contact position of the pair of electrode layers 2 and 2 at both longitudinal ends of the magnetoresistive element layer 1 having a rectangular shape. 7
Are laminated in this order. Since the soft magnetic layer 6 and the antiferromagnetic layer 7 are obtained by continuous film formation, there is no oxide film at the interface between them and an exchange coupling magnetic field is generated between both layers. Therefore, in JP-A-5-54337, it is described that this exchange coupling magnetic field also acts on the magnetoresistive effect element layer 1 and the inside of the magnetoresistive effect element layer 1 is made into a single magnetic domain. .

However, the action of the exchange coupling magnetic field generated between the soft magnetic layer 6 and the antiferromagnetic material layer 7 on the magnetoresistive effect element layer 1 is actually extremely weak, and the magnetoresistive effect element is therefore weak. It cannot be said that the single magnetic domain of the layer 1 is sufficiently achieved, and the effect of reducing Barkhausen noise can hardly be expected.

The present invention has been made in view of such circumstances, and it is possible to effectively bring the inside of the magnetoresistive effect element layer into a single magnetic domain state, and to effectively generate Barkhausen noise due to domain wall motion. It is an object of the present invention to provide a method of manufacturing a magnetoresistive effect type head that can be effectively reduced.

[0013]

A method of manufacturing a magnetoresistive effect head according to the present invention stores information recorded on a magnetic recording medium,
In a method of manufacturing a magnetoresistive effect head which reproduces by utilizing the resistance change of the magnetoresistive effect element layer facing the recording surface, the magnetoresistive effect element layer is continuously formed after the magnetoresistive effect element layer is formed. A step of reducing the thickness of two portions of the magnetoresistive effect element layer, which are separated by an appropriate length in the direction of the easy axis of magnetization, and a step of laminating and forming an antiferromagnetic material layer in a range including this reduced thickness portion. Characterize.

[0014]

In the present invention, after the magnetoresistive effect element layer is formed on the substrate, the magnetoresistive effect element layer is formed at two appropriate distances in the direction of the easy axis of magnetization, generally in the longitudinal direction. By reducing the thickness of both ends by a predetermined amount, the oxide film formed on the surface is removed and the magnetoresistive effect element layer underneath is further scraped off. An antiferromagnetic material layer is laminated and formed on the portion where the film is removed, and the magnetoresistive effect element layer and the antiferromagnetic material layer are brought into direct contact with each other without interposing an oxide film, and the crystal on the surface of the magnetoresistive effect element layer is formed. Barkhausen noise is enhanced by improving the orientation, improving the epitaxy with the antiferromagnetic layer, and making the magnetoresistive effect element layer a single magnetic domain state by the action of the exchange coupling magnetic field stably generated at the interface between both layers. Reduce the occurrence of. Further, the thickness of the magnetoresistive effect element layer is reduced only at both ends, and the center portion which is the track width is left as it is while maintaining the thickness at the time of formation, thereby preventing a decrease in output due to weakening of the magnetoresistive effect.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a perspective view of a magnetoresistive head obtained by a method of manufacturing a magnetoresistive head according to the present invention (hereinafter referred to as a method of the present invention).

This magnetoresistive head, like the conventional magnetoresistive head, has a rectangular magnetoresistive element layer 1 and a pair of electrodes, each of which is in contact with both sides in the longitudinal direction thereof. Layers 2, 2, while electrode layers 2,
The magnetoresistive element layer 1 extending further outside the contact position 2
Are provided with reduced thickness portions 10 and 10 at both ends thereof, and an antiferromagnetic material layer 5 is laminated on each of these reduced thickness portions 10 and 10. Each of these layers is protected by an insulating material that covers the whole. The layer 3 is laminated on the end surface of the substrate 4 which also serves as a slider. A magnetic shield layer for shielding magnetic noise from the outside is laminated on both sides in the thickness direction of the magnetoresistive effect element layer 1 and the electrode layers 2 and 2 via separate insulating layers. 1 are omitted in FIG.

2 to 6 are explanatory views of the procedure for carrying out the method of the present invention. In each of these figures, (a) is a vertical sectional view and (b) is a plan view.

The substrate 4 is made of, for example, alumina (Al
₂ O ₃ ) and titanium carbide (TiC), which are made of AlTiC (Al ₂ O ₃ —TiC), and a lower shield layer (not shown) and an insulating layer (not shown) are first formed on the substrate 4. ) And are laminated, and the magnetoresistive effect element layer 1 is formed thereon. The magnetoresistive effect element layer 1 is made of a ferromagnetic material such as NiFe alloy (permalloy) or NiCo alloy, and is formed on the surface of the substrate 4 by, for example, sputtering using an RF sputtering device, as shown in FIG. 20 nm
The film is formed to have a predetermined thickness before and after. This magnetoresistive effect element layer 1 also has, as shown in FIG.
It has a rectangular planar shape having a length of 50 μm to 60 μm and a width of about 6 μm, and the uniaxial magnetic anisotropy is induced in the film formation described above, and the length direction is the easy magnetization axis.

After that, as shown in FIG. 3, the photoresist film 8 is formed so as to cover the substrate 4 and the upper portion of the magnetoresistive effect element layer 1 except for two locations including both ends in the longitudinal direction of the magnetoresistive effect element layer 1. To form. The non-formed portion of the photoresist film 8 is not limited to the position shown in FIG. 3B, but may include two portions each separated by an appropriate length in the direction of the easy axis of magnetization (longitudinal direction). However, in order to effectively use the entire magnetoresistive effect element layer 1, the photoresist film 8 is formed at the position shown in FIG. 3, that is, at two locations including both ends in the longitudinal direction of the magnetoresistive effect element layer 1. It is desirable to set the non-formed part.

After the photoresist film 8 is formed, in this state, it is introduced into a film forming apparatus such as a dual ion sputtering apparatus, and Ar milling is first performed. As a result, the two portions on both ends of the magnetoresistive effect element layer 1 which are not covered with the photoresist film 8 are removed by the Ar ion sputtering, and as shown in FIG. Thick parts 10 and 10. The thickness of the reduced thickness parts 10 and 10 is
It can be set freely by controlling the milling time, but the thickness of the oxide film formed on the surface of the magnetoresistive effect element layer 1 is 2.5.
The thickness is about 1 nm, and it is necessary to completely remove it. If the thickness is 2 nm or less, the crystal orientation of NiFe is weakened and the epitaxial growth of the antiferromagnetic material layer 5 to be laminated later is hindered. Taking this into consideration, the thickness reduction from the surface of the magnetoresistive effect element layer 1 is 5n.
m or more, and the own thickness obtained after removal is 2
It is desirable to set within the range of not less than nm. This desirable range is obtained by the result of the test described later for examining the effect of reducing Barkhausen noise.

After the steps of forming the reduced thickness portions 10 and 10 as described above,
Subsequently, an antiferromagnetic material layer 5 having a predetermined thickness is formed by sputtering an antiferromagnetic material such as FeMn alloy as shown in FIG. Considering that a stable exchange coupling magnetic field is formed between the antiferromagnetic material layer 5 and the reduced thickness portions 10 of the magnetoresistive effect element layer 1, it is 15 n.
It is desirable that the thickness is not less than m and not more than 50 nm. The step of forming such an antiferromagnetic material layer 5 needs to be performed in a magnetic field in one direction.

After the steps of forming the antiferromagnetic material layer 5 as described above are completed, the substrate 4 is taken out from the film forming apparatus and the photoresist film 8 is removed by cleaning in an organic solvent. Figure 6
The state where the photoresist film 8 is removed is shown. In the forming process described above, the antiferromagnetic material layer 5 is also formed on the photoresist film 8 as shown in FIG. 5, but this part is removed at the same time in the removing process of the photoresist film 8, As shown in FIG. 6, the magnetoresistive effect element layer 1
The antiferromagnetic layer 5, 5 only in the range including the reduced thickness portions 10, 10 at both ends
5 remains. After that, the electrode layers 2 and 2 are formed inside the antiferromagnetic layers 5 and 5, respectively, each having a contact portion with the magnetoresistive effect element layer 1, and an insulating layer (not shown) and an upper portion are formed thereon. A shield layer (not shown) is laminated, and a protective layer 3 made of an insulating material is further formed so as to cover the upper portion of the shield layer, and the magnetoresistive head shown in FIG. 1 is obtained.

As described above, in the magnetoresistive head obtained by the method of the present invention, the antiferromagnetic material layer 5 is formed on the reduced thickness portions 10 and 10 from which the oxide film is removed at both ends of the magnetoresistive effect element layer 1. , 5 are laminated, a stable exchange coupling magnetic field is generated at the interface between the two, and the thinned portions 10, 10 are integrated with the magnetoresistive effect element layer 1. Therefore, the magnetoresistive effect element layer 1
Due to the action of the exchange-coupling magnetic field, the inside of the magnetic field is in a single magnetic domain state over the entire length, and Barkhausen noise in the reproduction output extracted between the electrode layers 2 and 2 can be significantly reduced.

Finally, the results of tests conducted to investigate the effect of Barkhausen noise reduction by the method of the present invention will be described. This test uses a substrate 4 in which a CoZrMo film (20 nm thick) for soft bias and a Ti film (10 nm thick) for magnetic separation are formed on a glass plate, and a magnetic resistance made of NiFe is formed on the surface of the substrate 4. The effect element layer 1 (thickness: 25 nm) is formed in a rectangular shape having a length of 60 μm and a width of 6 μm, and the magnetoresistive effect element layer 1 is provided with 25 pieces from each end.
Ar milling was performed in the range of μm to obtain 0, 2,
After removing only 4, 5, 7, 10, 15, 21, 21, 23 and 24 nm to obtain the reduced thickness portions 10 and 10, respectively, the antiferromagnetic material layer 5 made of FeMn (thickness: 20 nm) is formed on the upper portion of each of them. ) Is formed in a laminated manner, and a sense current of 6 mA is applied to each of the magnetoresistive heads in which the Cu electrode layers 2 and 2 are formed with a 10 μm active region left in the center of the magnetoresistive element layer 1. The output waveform obtained in an alternating magnetic field of 50 Hz was observed, and the presence or absence of disturbance of the output waveform due to Barkhausen noise was examined. The results are shown in Table 1.

[0025]

[Table 1]

As shown in Table 1, the reduced thickness portions 10, 10
Distortion of the output waveform is observed in each example in which the removal amount is 0 to 4 nm and the removal amount is 24 nm when obtaining Of these, the former is due to insufficient removal of the oxide film on the surface of the magnetoresistive effect element layer 1 and insufficient crystal orientation on the surface of the magnetoresistive effect element layer 1. The latter is due to the fact that the epitaxial growth of the antiferromagnetic layer 5 is hindered by the insufficient thickness of the reduced thickness portions 10 and 10 after the removal.
On the other hand, when the amount of removal is 5 to 23 nm, the disturbance of the output signal due to Barkhausen noise is not observed, and the method of the present invention properly adjusts the amount of removal when the reduced thickness portions 10 and 10 are obtained. By setting, that is, within a range in which the thickness reduction amount from the surface of the magnetoresistive effect element layer 1 becomes 5 nm or more, and the thickness of the thickness reduction parts 10 and 10 obtained in the removed portion becomes 2 nm or more. By setting it, it became clear that it is effective in reducing Barkhausen noise.

[0027]

As described in detail above, according to the method of the present invention,
2 separated by an appropriate length in the direction of the easy axis of magnetization of the magnetoresistive element layer
The oxide film formed on the surface is removed by reducing the thickness by a predetermined amount, and after that, the antiferromagnetic material layer is formed continuously on the reduced portion where the oxide film has been removed. The effect element layer and the antiferromagnetic material layer are in direct contact with each other without interposing an oxide film, a stable exchange coupling magnetic field is generated at the interface between both layers, and the inside of the magnetoresistive effect element layer is brought into a single magnetic domain state. The present invention has an excellent effect such that Barkhausen noise caused by the movement of the domain wall can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetoresistive head obtained by the method of the present invention.

FIG. 2 is an explanatory diagram of an implementation procedure of the method of the present invention.

FIG. 3 is an explanatory diagram of an implementation procedure of the method of the present invention.

FIG. 4 is an explanatory diagram of an implementation procedure of the method of the present invention.

FIG. 5 is an explanatory diagram of an implementation procedure of the method of the present invention.

FIG. 6 is an explanatory diagram of an implementation procedure of the method of the present invention.

FIG. 7 is a perspective view of a general magnetoresistive head.

FIG. 8 is a perspective view of a conventional magnetoresistive head in which Barkhausen noise is reduced.

[Explanation of symbols]

 1 Magnetoresistive Element Layer 2 Electrode Layer 3 Protective Layer 4 Substrate 5 Antiferromagnetic Layer 8 Photoresist Film 10 Reduced Thickness Section

Claims (1)

[Claims] 1. A method of manufacturing a magnetoresistive head in which recorded information of a magnetic recording medium is reproduced by utilizing a resistance change of a magnetoresistive element layer facing a recording surface of the magnetoresistive element. A step of successively reducing the thickness of the magnetoresistive effect element layer at two positions separated by an appropriate length in the direction of the easy axis of magnetization, and a range including this reduced thickness portion, and anti-strengthening A method of manufacturing a magnetoresistive head, comprising the step of stacking magnetic layers.