WO1994019794A1

WO1994019794A1 - Magnetoresistive magnetic head

Info

Publication number: WO1994019794A1
Application number: PCT/JP1994/000296
Authority: WO
Inventors: Hideo Suyama; Tetsuo Sekiya; Shuichi Haga; Wataru Ishikawa
Original assignee: Sony Corporation
Priority date: 1993-02-25
Filing date: 1994-02-24
Publication date: 1994-09-01
Also published as: JPH06251336A

Abstract

This invention discloses a vertical magnetoresistive magnetic head wherein a magnetoresistive element is disposed in a vertical direction with respect to a sliding surface facing a magnetic recording medium, and a tip electrode laminated on a distal end is exposed at the sliding surface. The magnetoresistive element has a laminate film structure formed by laminating a pair of ferromagnetic thin films through a non-magnetic metal layer. The non-magnetic metal layer is made of Cu, having a thickness less than 10 nm. The ferromagnetic thin film is a thin film of a Ni-Fe alloy, Ni-Fe-Co alloy, and so forth, and preferably it has a thickness less than 10 nm. The magnetoresistive element is sandwiched between a pair of shield magnetic substances.

Description

TECHNICAL FIELD The present invention relates to a magneto-resistance effect type magnetic head suitable for reading out an information signal recorded on a hard disk, for example. Background technology For example, a read-only magnetic head mounted on a hard disk drive or the like has a configuration that reads current resistance and changes in resistance due to signal magnetic flux as a voltage change because of its excellent short-wavelength sensitivity. In addition, a magnetoresistive head (hereinafter referred to as an MR head) is generally used.

As such an MR head, for example, as shown in FIG. 1, a magnetoresistive effect element 102 (hereinafter, referred to as an MR element 102) is formed on a substrate 101 made of a nonmagnetic material as a slider. A so-called horizontal MR head has been proposed in which the longitudinal direction is arranged so as to be parallel to the sliding surface 103 (hereinafter referred to as ABS surface 103) with the hard disk. .

In this horizontal MR head, the MR element 102 is arranged such that one side edge in the longitudinal direction is exposed on the ABS 103, and the MR element 102 is provided with 0 A sense current is supplied in parallel with 3 The MR element 102 is provided with wiring conductors 104, 105 at both ends perpendicular to the ABS surface 103.

By the way, in this horizontal MR head, as shown in FIG. 2, the MR element 102 is made of a thin ferromagnetic thin film 102b, 1 By forming a multilayer film structure in which 02c and 102d are stacked, it is possible to effectively avoid generation of noise (Barkhausen noise) due to domain wall movement.

In particular, by using Fe-Ni for the ferromagnetic thin films 102b and 102c, Fe-Mn for the ferromagnetic thin film 102d, and Cu for the intermediate layer 102a, the giant magnetoresistance effect is obtained. Can be obtained. Therefore, improvement in reproduction output can be expected, which is very advantageous for MR heads.

However, in the above-described horizontal MR head, since one side edge of the MR element 102 is exposed to the ABS 35103, if Cu constituting the MR element 102 is corroded, the MR element 102 Function is deteriorated. In other words, in the horizontal MR head, the MR element 102 provided between the wiring conductors 2 and 3 becomes a magnetically sensitive part, and the corrosion of Cu in this part lowers the magnetic permeability of this part. As a result, the function of the MR element 102 deteriorates. Disclosure of the invention

• The present invention provides a magnetic field that can greatly improve the reproduction output by the giant magnetoresistance effect without deteriorating the function of the MR element even if the nonmagnetic metal layer of the MR element exposed on the ABS surface is corroded. Resistive magnetic head The purpose is to provide

In order to achieve the above-mentioned object, the present invention provides a magnetoresistive element having a laminated film structure in which a pair of ferromagnetic thin films are laminated via a nonmagnetic metal layer, In the vertical type magnetoresistive effect type magnetic head in which the tip electrode laminated on the tip side is exposed on the sliding surface, the nonmagnetic metal layer is It is characterized by consisting of Cu.

Further, in such a magneto-resistance effect type magnetic head, the film thickness of Cu is less than 10 nm.

In the present invention, a giant magnetoresistive effect is obtained because the MR element has a laminated film structure in which a pair of ferromagnetic thin films are laminated via a nonmagnetic metal layer made of Cu. Is greatly improved. Further, in the present invention, the MR element is provided perpendicular to the ABS surface, and the tip electrode laminated on the tip side of the MR element is provided so as to be exposed on the ABS surface. Even if the non-magnetic metal layer (C u) facing the ABS surface is corroded, the magnetic permeability of such a vertical MR head is the area sandwiched between the electrodes. It is sufficiently ensured by the upper and lower ferromagnetic thin films provided between the layers. Therefore, the function of the MR element does not deteriorate in such a vertical MR head as in the horizontal MR head.

Also, in the present invention, if the film thickness of Cu used as the intermediate layer of the MR element having a laminated film structure is made extremely thin, less than 10 nm, the track width is narrowed to increase the track density. Even in this case, the reproduced signal from the medium can be read stably, and the magnetoresistance effect can be obtained. Fig. 1 is a schematic plan view of a horizontal MR head in which MR elements are arranged parallel to the ABS.

Fig. 2 is an enlarged perspective view of the main part of a horizontal MR head in which the MR element is arranged parallel to the ABS. FIG.

FIG. 4 is an enlarged perspective view of a main part of the MR head to which the present invention is applied, in which an MR element part is partially broken.

FIG. 5 is a characteristic diagram showing a resistance change rate when the thickness of a single Fe-Ni film is changed.

Fig. 6 is a schematic diagram of an MR head for explaining a reproduction effective gap length.

Fig. 7 is a characteristic diagram showing the resistance change of the MR element when the magnetic field is swept positively and negatively in an MR head having a ferromagnetic thin film thickness of 3 Onm.

Figure 8 is a characteristic diagram showing the resistance change of the MR element when the magnetic field is swept positively and negatively in an MR head with a ferromagnetic thin film thickness of 10 nm or less.

FIG. 9 is a characteristic diagram showing the rate of change of resistance when the film thickness of Cu is changed. Ο Best Mode for Carrying Out the Invention Hereinafter, referring to the drawings for specific examples to which the present invention is applied. Shina The power will be described in detail.

MR head of the present embodiment, as shown in FIG. 3, on a substrate 1 made of a nonmagnetic material A 1 ₂ 0 ₃ -T i C such as a slider, the wiring conductors 2 for supplying a sense current, 3 is connected to the front end and the rear end, respectively, to form an MR element 4, and a pair of shield magnetic bodies 5, 6 are formed so as to sandwich the MR element 4 from above and below. .

As shown in FIG. 4, the MR element 4 is formed as a pattern having a rectangular planar shape, and its longitudinal direction is perpendicular to the ABS surface 7 which is a sliding surface for the hard disk (perpendicular direction). And one end edge 4 d faces the ABS surface 7. The MR element 4 is made of a ferromagnetic thin film such as Vermalloy, and is formed by vapor deposition or sputtering. The MR element 4 includes a pair of ferromagnetic thin films (MR films) 4 b, 4 b, It has a laminated film structure in which 4c are laminated. In this embodiment, in order to obtain a giant magnetoresistance effect, Cu is used as the nonmagnetic metal layer 4a, and a Ni—Fe alloy or a Ni—Fe is used for the ferromagnetic thin films 4b and 4c. — Co alloy was used.

The wiring conductors 2 and 3 connected to the front end and the rear end of the MR element 4, respectively, are formed on the side facing the shield magnetic body 6 in the upper layer. Of these wiring conductors 2 and 3, the wiring conductor 2 provided on the front end side (the ABS surface 7 side) of the MR element 4 has a substantially rectangular planar shape with one edge 2a facing the ABS surface 7. It is formed as a small conductor pattern. The wiring conductor 2 is perpendicular to the MR element 4. And are electrically connected at a portion to be stacked on the MR element 4.

On the other hand, the wiring conductor 3 provided on the rear end side also has one end laminated on the rear end of the MR element 4 and the other end electrically connected to the MR element 4.

By providing the wiring conductors 2 and 3 for the MR element 4 as described above, a sense current flows in the MR element 4 in a direction orthogonal to the ABS plane 7 (longitudinal direction of the MR element 4).

A bias conductor 8 for applying a bias magnetic field to the MR element 4 is provided between the wiring conductors 2 and 3. The bias conductor 8 is provided on a central portion in the longitudinal direction of the MR element 4 so as to cross (cross) the MR element 4 vertically. The bias conductor 8 is laminated on the MR element 4 via an insulating film 9.

Of the shield magnetic members 5 and 6 sandwiching the MR element 4 from above and below, the lower shield magnetic member 5 is made of a soft magnetic metal layer such as permalloy. It is formed as a wide pattern having a substantially rectangular planar shape with one end thereof facing. On the other hand, the upper shield magnetic body 6 is also made of a soft magnetic metal layer such as permalloy similarly to the lower shield magnetic body 5, and has a flat rectangular shape with one end facing the ABS surface 7. It is formed as a pattern. Further, the shield magnetic body 6 is bent so as to be close to the MR element 4 on the ABS surface 7 side, so that the distance between the shield magnetic body 6 and the wiring conductor 2 on the distal end side is reduced.

In addition, between the lower shield magnetic body 5 and the MR element 4, the lower layer Magnetic gap for reproduction g! A 1 that functions as a gap film that constitutes

A base film 10 composed of 2/3 is provided. Between the wiring conductors 2 of the upper shield magnetic body 6 and the front end side, the insulating film 1 made of A 1 ₂ 0 _3, etc. which serves as a gap film constituting the upper layer of the reproducing magnetic formic Yap g ₂ 1 is provided. The insulating film 11 is also provided between the MR element 4 and the upper shield magnetic body 6 to prevent magnetic coupling between the MR element 4 and the shield magnetic body 6. Further, a protective film layer 12 for protecting the MR head is laminated on the upper shield magnetic body 6.

In the MR head configured as described above, one end 4 d of the MR element 4 is exposed on the ABS surface 7. However, since the MR element 4 is arranged perpendicular to the ABS surface 7, for example, Even if the one edge 4d of the MR element 4 is corroded, the magnetic permeability is between the wiring conductors 2 and 3, so the magnetic permeability is the upper and lower sides of the nonmagnetic metal layer 4a in this MR sensitive part. The ferromagnetic thin films 4b and 4c are sufficiently secured. Therefore, a decrease in the reproduction output can be suppressed.

Also, in this embodiment, the frequency characteristics during reproduction are improved, the S / N ratio is increased up to higher frequencies, and even when the track is narrowed, the reproduction output is greatly improved by the giant magnetoresistance effect. Reduce the thickness of the MR element 4 itself so that the thickness of the magnetic layers 4 b and 4 c is 10 nm or less, and the thickness of the nonmagnetic metal layer 4 a is less than 10 nm (several nm). I do. The above object can be achieved by defining the film thickness of the MR element 4 in this manner for the following reason.

For example, when the MR element 4 is a single film of a Ni—Fe alloy and the film thickness is 3 O nm, the resistance change rate becomes larger as shown in FIG. It will be big. The rate of change in resistance referred to here indicates the ratio of the change in resistance when a magnetic field is applied until the ferromagnetic material is saturated with respect to the resistance value of the ferromagnetic material in the absence of a magnetic field. As can be seen from FIG. 5, the value with a resistance change rate of about 2% at a film thickness of 30 nm rapidly decreases at a thickness of 20 nm or less. The main reason for this is that the resistance increases rapidly as the thickness decreases. Therefore, if the thickness is too thin, for example, 2 O nm or less, it is adopted because the increase in resistance becomes a problem as a head (inductance becomes too high), and the variation in film formation becomes large. Had not been. '' However, in recent years, under the situation of extremely high density, as represented by hard disk drives, the linear recording density and track density have become extremely large, and have exceeded 100 KFCI and 500 TPI or more. The performance must be achieved. At this high density, the reproduction gap must be 0.15 m and the reproduction head width must be 3 zm or less. Here, for example, when the MR element 4 having a laminated film structure in which the thickness of the ferromagnetic thin films 4 b and 4 c is 30 nm and the thickness of the nonmagnetic metal layer 4 a is 10 nm is used, As the film thickness increases, the frequency characteristics during reproduction cannot be extended to high frequencies. Also, the stability of the MR element 4 is degraded. Furthermore, a giant magnetoresistance effect cannot be obtained.

Play effective gap length L in head to MR, as shown in FIG. 6, which is substantially plus the distance t ₂ between the thickness t of the MR element 4, and the MR element 4 shielding magnetic member 6 and Become. However, it is limited to the case where the distance between the shield magnetic bodies 5 and 6 is the same when viewed from the MR element 4. Therefore, if the overall thickness of the MR element 4 is about 7 O nm, the distance between the MR element 4 and the shield magnetic body 6 must be 0.1 zm or less. Difficult to create. For this reason, it is advantageous to make the thickness of the MR element 4 significantly smaller, specifically, 20 nm (0.02 mm) or less. For example, it is desirable that the ferromagnetic thin films 4b and 4c be made to have a thickness of 10 nm using a Ni—Fe alloy, and the nonmagnetic metal layer 4a be made to have a thickness of 2 nm using Cu.

By the way, if the thickness of the ferromagnetic thin films 4b and 4c is about 30 nm, as shown in Fig. 7, the current flowing through the MR element 4 by about 10 mA causes Changes in resistance can sometimes show discontinuous values or cause hysteresis. This poses a problem for stability as a playback head.

Therefore, the ferromagnetic thin films 4 b and 4 forming the MR element 4 are formed to have a thickness of 1 Onm or less, and the intermediate nonmagnetic metal layer 4 a is formed of A 12 12 ₃曆 (4 nm If a layer with a continuity (film formation) with a thickness of about 2 nm, such as Cu or vanadium, is used instead of an element with the same shape, the continuity as shown in Fig. 8 can be obtained. Therefore, stable characteristics without hysteresis can be obtained. This is a necessary condition for obtaining stable characteristics as a reproduction head.

The reason why the MR element 4 is stabilized when the film thickness is reduced is that when the width of the MR element 4 is 3 m or less to 1 zm, the influence of the demagnetizing field due to the thickness and the width increases.

When the thickness of the ferromagnetic thin films 4b and 4c is reduced to 10 nm or less compared to about 30 nm, the rate of change in resistance decreases as shown in FIG. Although it is missing, it is rarely used in the past, but making it thinner is not necessarily a disadvantage. The reason is that the same signal value (current density increases) and the same signal magnetic field When it enters (the magnetic flux density is large), the resistance change increases in proportion to each. (However, it is assumed that the resistance change rate ΔρΖρ has hardly changed.)

In addition, when Cu is used as the nonmagnetic metal layer 4a, a special behavior as shown in FIG. 9 is exhibited. This is generally called a giant magnetoresistance effect. Figure 9 shows the results when Νί-Fe-Co was used as the ferromagnetic thin films 4b and 4c, the film thickness was reduced to 10 nm or less, and Cu was varied from 1 nm or less to 4 nm. It shows the rate of change in resistance. As can be seen from this figure, it can be seen that the resistance change rate changes periodically depending on the thickness of Cu. In the present embodiment, Cu of 2 nm (20 A): Select and read ₀

When the Cu film thickness is 1. Onm and 2. Onm, the magnetization directions of the ferromagnetic thin films 4 b and 4 c where the giant magnetoresistance effect occurs are different. This is because it is easy to use as an MR head, and the film formation stability, thickness, variation, etc. are superior to 1. Onm. Therefore, by making the film thickness of the ferromagnetic thin films 4 b and 4 c 10 nm or less and using less than 1 Onm (several nm or less) of Cu as the nonmagnetic metal layer 4 a, the MR element 4 becomes stable. In addition, a stable track can be obtained even if the track is narrowed. Furthermore, when a head is used, the adverse effect of the MR element thickness is reduced, good frequency characteristics are easily obtained, and the output can be increased by using the giant magnetoresistance effect by using Cu for the nonmagnetic metal layer 4a.

As described above, the specific embodiments to which the present invention is applied have been described. However, the present invention is not limited to the above-described embodiments, and various changes can be made. For example, in the previous example, a dedicated Although the ground conductor 8 is used, a part of the wiring conductor 3 provided on the rear end side is laminated via the insulating layer 9 so as to cross the MR element 4, and electricity is supplied to the conductor crossing the MR element 4. A bias magnetic field may be applied to the MR element 4 by a current. This eliminates the need for the dedicated bias conductor 8, and allows the head to be reduced in size by reducing the number of terminals.

In any case, in the present invention, since the MR element formed by laminating the ferromagnetic thin film via the non-magnetic metal layer is arranged perpendicular to the ABS surface, the MR element facing the ABS surface Even if the edge of the vertical MR head corrodes, the magnetic permeability between the top and bottom electrodes of the vertical MR head is the magnetic sensing part, so the magnetic permeability is the upper and lower ferromagnetic layers provided between the nonmagnetic metal layers. The body thin film is sufficiently ensured, and a decrease in reproduction output can be suppressed. Further, in the present invention, the MR element has a laminated film structure in which a ferromagnetic thin film is laminated via a nonmagnetic metal layer made of Cu, and the film thickness is set to be small. The frequency characteristics at the time are improved, and it is possible to reproduce to a higher frequency with a certain SZN ratio secured. Furthermore, even if the track is narrowed, the MR element can be stabilized and the reproduction output by the giant magnetoresistance effect can be greatly increased.

Claims

The scope of the claims

1. A magnetoresistive element having a laminated film structure in which a pair of ferromagnetic thin films is laminated via a non-magnetic metal layer is disposed in a direction perpendicular to a sliding surface with respect to a magnetic recording medium. A vertical magneto-resistance effect type magnetic head in which the tip electrode laminated on the sliding surface is exposed to the sliding surface, wherein the non-magnetic metal layer is made of Cu. Magnetic head.

2. The magnetoresistive head according to claim 1, wherein the thickness of Cu is less than 1 Onm.

3. The magnetoresistive head according to claim 1, wherein the ferromagnetic thin film has a thickness of 10 nm or less.

4. The magnetoresistance effect type magnetic head according to claim 1, wherein the magnetoresistance effect element is disposed between a pair of shield magnetic bodies.

5. The magnetoresistive magnetic head according to claim 1, wherein the ferromagnetic thin film is a Ni—Fe alloy or a Ni—Fe—Co alloy thin film.