JP3331389B2 - Perpendicular magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetization type magnetic head provided in a magnetic disk drive for recording and reproducing digital information. In particular, the present invention relates to a perpendicular magnetic head capable of responding to high-density recording because a reproducible signal can be obtained much larger than a conventional inductive head.

[0002]

2. Description of the Related Art IEEE Trans. Magn, MAG-13 (197
7) As described on page 1272, perpendicular magnetic recording is a recording method in which magnetization is performed in the in-plane perpendicular direction of a magnetic recording medium, and corresponds to a high recording density.

For this perpendicular magnetic recording, a magnetic head different from the conventional one is required.
l. 13 (1989), page 113, JP-A-6-18
No. 0810, etc. However, these perpendicular magnetic heads use the same inductive head as for recording for reproduction, and the intensity of the output signal is not sufficient.

On the other hand, in horizontal magnetic recording widely used at present, IEICE Technical Report MR92-61 (1992),
As in the case of a page, a magnetoresistive read head (MR head) has begun to be used to obtain a higher read output in high-density recording.

Japanese Patent Application Laid-Open No. 4-278210 discloses that a reproduction signal is obtained by using an MR element in a perpendicular magnetic head. However, since the main magnetic pole has a structure separated by an MR element, writing is not possible. Therefore, a large magnetic field could not be generated, and it was only for reproduction.

The MR element of a magnetic head is disclosed in Japanese Patent Laid-Open No. 4-182.
As disclosed in Japanese Patent Application Laid-Open No. 913, a structure in which a magnetic flux flows perpendicular to the film surface has been proposed. However, as described in the specification, NiFe
Obviously, the use of the above is disadvantageous over the structure in which the magnetic flux flows in the film surface direction. In addition, it is a normal horizontal recording head, and its effect is small. On the other hand, in the same way, the structure installed so that magnetic flux flows perpendicular to the film surface is Hall
A magnetic head using an element has been proposed. In this case, even if the magnetic flux flows perpendicular to the film surface due to the Hall effect, the magnetic flux can be detected with high efficiency.

As described above, there are reports on various magnetic head structures, but the reproduction efficiency of the perpendicular magnetic head is further improved.
A major problem remains with respect to an MR magnetic head that uses one main pole for read / write.

[0008]

An MR composite magnetic head that further improves the reproduction efficiency of a perpendicular magnetic head requires a structure different from a normal horizontal recording MR head. That is, because of the extremely high density, the thickness of the write main magnetic pole is as thin as 0.5 μm or less, and it is extremely difficult to perform positioning by using a read-only magnetic pole formed at another position during reproduction. Therefore, it is important to use both the write magnetic pole and the read magnetic pole.
However, in a normal yoke type MR head in which a magnetic pole and a space are provided to allow a current to flow in the MR element, the magnetic field at the time of writing becomes insufficient.

[0009]

SUMMARY OF THE INVENTION Such a perpendicular magnetic MR
It is possible to solve the problems of the head and obtain a high reproduction signal by the following present invention.

(1) A perpendicular magnetic head wherein a magnetic field detecting layer is formed between a main magnetic pole and a yoke magnetic layer magnetically coupled to the main magnetic pole portion.

(2) The specific resistance of the portion of the main magnetic pole magnetic film that is in electrical contact with the magnetic field detection layer is ρ1, the specific resistance of the portion of the yoke magnetic layer that is in electrical contact with the magnetic field detection layer is ρ2, and the magnetic field detection layer is The perpendicular magnetic head according to the above (1), wherein, when the specific resistance of ρ3 is ρ3, ρ1 and / or ρ2 is three times or more of ρ3.

(3) The upper yoke magnetic layer is an alloy film formed by an electroplating method, and the specific resistance of the film on the surface layer of the alloy film is higher than that of an inner portion thereof. The perpendicular magnetic head according to (1) or (2).

(4) The yoke magnetic layer is a NiFeMo-based alloy film formed by electroplating,
The perpendicular magnetic head according to any one of the above (1) to (3), wherein the Mo content of the film on the uppermost surface of the upper yoke is higher than that of the lower portion.

(5) The yoke magnetic layer is an alloy film formed by electroplating, and the film on the outermost surface of the upper yoke is
The perpendicular magnetic head according to any one of the above (1) to (3), which is manufactured by reverse electrolysis.

(6) The perpendicular magnetic head according to any one of (1) to (5), wherein the magnetic field detecting layer is a giant magnetoresistive film.

(7) The perpendicular magnetic head according to any one of (1) to (5), wherein the magnetic field detecting layer is a Hall element.

[0017]

In the present invention, positioning is facilitated by using the main magnetic pole of the vertical head for both reproduction and writing. Further, a magnetic field detecting section is inserted between the main magnetic pole section and the upper yoke section, and at least one side of the magnetic flux inflow section of the magnetic field detecting section is detected in order to promptly introduce a magnetic flux into the magnetic field detecting section. Since the insulating layer is insulated by a magnetic film having a sufficiently large specific resistance of at least three times, preferably at least five times the specific resistance of the layer, a high writing capability and a large reproduction output can be obtained.

[0018]

FIG. 3 is a sectional view of a conventional perpendicular magnetic head. 1 and 2 are sectional views of a perpendicular magnetic head according to the present invention. In both figures, 6 is the main pole, 3 is the upper yoke film, 2
Is a lower yoke film. The main magnetic pole part is permalloy, NiFeMo, FeN, FeYO, FeHfO, C
It is preferable to use a soft magnetic material such as oZr.

A multi-layer high-resistance soft magnetic material as disclosed in Japanese Patent Application Laid-Open No. 5-101930 can also be used. As described above, when the specific resistance of the main magnetic pole material itself is sufficiently higher than the specific resistance of the magnetic field detection layer, an insulating layer for insulation only between the main magnetic pole and the magnetic field detection layer becomes unnecessary. When a material having a small specific resistance such as permalloy is used, it is necessary to provide an insulating layer having a large specific resistance between the material and the magnetic field detecting layer. As the insulating layer, a nonmagnetic material such as alumina can be used, but NiFeMo, FeN, FeYO, Fe
It is preferable to use a soft magnetic material having a high specific resistance, such as HfO, CoZr, and ferrite.

Since the upper yoke and the return yoke are thick, a molybdenum permalloy film or the like formed by electroplating is used in consideration of productivity. This is because not only is the magnetic permeability higher than that of a permalloy film, but also it is easy to increase or decrease the molybdenum content in the film by changing the current density during film formation. As the molybdenum content in the film increases, the soft magnetic properties slightly deteriorate, but the specific resistance of the film dramatically increases as shown in FIG. 5, and a value of 300 μΩcm or more is obtained. Therefore, as described later, it is not necessary to form an electric insulating layer between the magnetic field detecting layer and the upper yoke, which greatly contributes to simplification of the head structure. When a permalloy film is used, the same insulation effect can be obtained by performing reverse electrolysis and dissolving the permalloy plating layer on the surface to form a layer having a high specific resistance with a high sulfur-oxygen content. is there.

When a current is applied to the coil 5, magnetic flux enters the external recording medium from the tip of the main magnetic pole 6 and is magnetized to perform recording. At this time, if the main magnetic pole is disconnected in the middle, a strong magnetic field cannot be generated, the medium cannot be sufficiently magnetized, and the overwrite characteristics and the like deteriorate. For this reason, it is not preferable to divide the main magnetic pole to guide the magnetic flux to the magnetic field detection layer.

In the magnetic field detecting layer of the present invention, a giant magnetoresistive film or a Hall element is used. The giant magnetoresistive film has a much higher sensitivity to magnetic fields than conventional anisotropic magnetoresistive effects such as permalloy, so that sufficient reproduction output can be obtained even when magnetic flux flows in the plane. . Such a giant magnetoresistive film is realized by an artificial lattice film, which has a structure in which thin films having a thickness on the order of the atomic diameter of metal are periodically laminated, and has different characteristics from bulk metal. In recent years, attention has been paid to show As one type of artificial lattice, there is a magnetic multilayer film in which ferromagnetic metal thin films and non-magnetic metal thin films are alternately laminated on a substrate, and magnetic multilayer films such as iron-chromium type and cobalt-copper type have been known. Have been. Among them, iron-chromium type (Fe
/ Cr) is 40 at ultra-low temperature (4.2K).
% Of the magnetoresistive change (Phy
s. Rev. Lett 61, 2472, 1988
Year).

However, in this artificial lattice magnetic multilayer film, the external magnetic field (operating magnetic flux intensity) at which the maximum resistance change occurs is more than ten kOe
Large, up to several tens of kOe, which is not practical. In addition, an artificial lattice magnetic multilayer film of Co / Ag or the like has been proposed, but even in these, the operating magnetic field intensity is too large.

Under such circumstances, a ternary artificial lattice magnetic multilayer film exhibiting a giant MR change due to induced ferrimagnetism in which two magnetic layers having different coercive forces are stacked via a nonmagnetic layer has been proposed. . For example, the magnetic thin films adjacent via the non-magnetic layer have different Hc, and the thickness of each layer is 200 μm.
A or less (Japanese Patent Laid-Open No. 4-218982). Also, a new structure called a spin valve film has been proposed.

This is because two NiFe layers are formed via a non-magnetic layer, and a FeMn layer is formed adjacent to one NiFe layer.
It has a configuration in which layers are arranged. Here, since the FeMn layer and the adjacent NiFe layer are directly coupled by an exchange coupling force, the magnetic spin of the NiFe layer is several tens to several hundreds.
The direction is fixed up to the Oe magnetic field strength. One Ni
The spin of the Fe layer can change its direction freely by an external magnetic field. As a result, a magnetoresistance change rate (MR change rate) of 2 to 5% is realized in a small magnetic field range of about the coercive force of the NiFe layer.

Further, since the Hall element can effectively detect the in-plane perpendicular magnetic flux component, a high reproduction signal can be obtained even with the magnetic head having this structure. InSb as a Hall element,
Materials such as InAs and GaAs can be used.

In the electric insulating layer, the sense current flowing to the magnetic field detecting layer is shunted to prevent a reduction in reproduction efficiency.

If the specific resistance of the electrical insulating layer is at least three times the specific resistance of the magnetic field detecting layer, and particularly preferably at least five times, a decrease in the detection sensitivity due to shunting can be prevented. If the specific resistance is less than three times, the influence of the shunt is large, and as a result, the magnetic field detection sensitivity is reduced and the output is reduced. The upper limit is limited by the material. For example, in the case of a NiFeMo plated film, the specific resistance of the film is about 350 μΩcm so that the soft magnetic characteristics do not deteriorate so much, which is 10 to 15 times that of the magnetic field detecting layer. The current shunt affects not only the specific resistance of the film but also the film thickness. However, when thin films are stacked, the resistance at the interface between the films is greatly affected, and the specific resistance of the film itself has a large effect on the interface resistance. can get.

The electric insulation layer must be provided on both sides of the magnetic field detecting layer. However, the main magnetic pole itself can have the same effect as the electric insulating layer. In this case, the main magnetic pole may be formed only on the upper yoke side as shown in FIG. As shown in FIG. 2, when a molybdenum permalloy film or the like is used as an upper yoke material and the specific resistance of the uppermost layer is set to three times or more, particularly preferably five times or more, the specific resistance of the magnetic field detecting layer, the uppermost layer is substantially In order to effectively function as an electrical insulating layer, plating can be continuously formed from the same apparatus and the same plating bath. As described above, the electric insulating layer according to the present invention is a magnetic film having a specific resistance of three times or more that of the magnetic field detecting layer, and is effectively used for insulating the upper and lower portions of the magnetic field detecting layer. It is preferable to use a material that can also be expected on at least one side.

The molybdenum permalloy plating film is prepared by adding tartaric acid or a salt thereof to a usual permalloy plating bath at 0.1 mol / mol.
A film can be formed by adding an appropriate amount of ammonium molybdate ion from 1 to 1 mol / liter. The bath temperature during film formation is in the range of room temperature to 60 ° C., and the current density is 0.1
A range of A / dm ² to 3 A / dm ² is preferred. When the content of molybdenum ions in the bath is constant, the molybdenum content in the film increases as the current density during film formation decreases. That is, a high permeability molybdenum permalloy film having a molybdenum content of 2 to 5 wt% in the upper yoke film forming step is formed by several μm.
After forming the m film, it is possible to form a high resistivity thin film having a molybdenum content of 5 wt% or more by performing a short-time electrodeposition while reducing the current density. There is no problem if the thickness of the high specific resistance molybdenum permalloy layer as the electric insulating layer is 500 A or more.

In order to obtain a high specific resistance layer by reverse electrolysis of the permalloy plating film, reverse electrolysis is applied in the final stage of ordinary film formation. Reverse electrolysis amounts current density at the time of 0.2 Amps from the time of 0.01 amps is 1A / dm ² from 0.01 A / dm ^2. When the reverse voltage starts to be applied, the bath voltage rises,
It is preferable to determine while looking at the bath voltage.

[0032]

EXAMPLES Examples of the present invention and comparative examples will be described below in detail. <Embodiment 1> An example of the head structure of the present invention is shown as Embodiment 1. 2, the main magnetic pole 6 was formed of a FeYO film having a specific resistance of 150 μΩcm and a magnetic permeability of 1500 formed by a sputtering method. The thickness of the main magnetic pole 6 was 0.1 μm, the width was 10 μm, and the amount of protrusion from the upper yoke was 5 μm. The upper yoke 3 is 15 μm thick and 20 μm wide, and the return yoke 2 is 8 μm thick and 150 μm wide.
Each of them is a molybdenum permalloy film formed by an electroplating method and has a specific resistance ρ of 60 μm with a molybdenum content of 4 wt%.
Ωcm. And 0.1 of the uppermost layer of the upper yoke
μm has a molybdenum content of 18 wt% and a specific resistance of 300 μm
Ωcm. As the magnetic field detection layer, an induction ferrimagnetic artificial lattice film formed by MBE and having a specific resistance of 30 μΩcm was used.

On a substrate, an alumina film was formed on a 3-inch ALTIC (0.5 mm thick) by sputtering.
A film having a thickness of μm was used. The return yoke portion has a current density of 1 A / dm ² by electroplating using a bath having the following composition.
A film was formed at a bath temperature of 40 ° C. and a pH of 4.5 for 30 minutes.

Nickel sulfate 1.25 mol / l Iron sulfate 0.015 mol / l Boric acid 0.4 mol / l Ammonium chloride 0.25 mol / l Saccharin 2 g / l Potassium sodium sodium tartrate 0.5 mol / l Membrane composition Was 79 wt% Ni-17 wt% Fe-4 wt% Mo. A novolak-based photoresist was used as an insulating material for the magnetic core, and the coil was formed by electroplating from a sulfuric acid bath for 60 minutes. The upper yoke was also formed under the same conditions as the return yoke, except that the current density was reduced to 0.1 A / dm ² only for the last 5 minutes.

The magnetic field detecting portion is formed by depositing 50 A of Cr to form an underlayer, and then NiFe (50) -Cu (50) -Co
(50) -Cu (50) -NiFe (50) were repeatedly laminated in order twice to form a magnetic multilayer film. The deposition conditions are
Ultimate pressure 1.3 × 10 ^-10 Torr, deposition pressure 1.2 × 1
0 ^-9 Torr, the substrate temperature is about 35 ° C, and each material is 0.2
Film formation is performed by a vapor deposition method (MBE method) under ultra-high vacuum while applying a magnetic field in the plane of the substrate and in a direction parallel to the measurement current at a film formation rate of about 0.3 A / sec. Thereafter, a pattern of 20 μm × 6 μm is formed, and an electrode having a track width of 3 μm is formed thereon. Then, the main magnetic pole is formed by rf sputtering using oxygen in an atmosphere of 0.2 to 0.1 μm in an argon atmosphere.
A film was formed containing about 5% by volume. 78 at% Fe-9 at
% Y-13 at% O. Finally, after forming a photoresist insulating layer, a coil layer, an alumina protective film, and the like, the head piece was machined and assembled to obtain a perpendicular magnetic head.

This perpendicular magnetic head has a measuring current of 12 mA and a recording medium of 8000 ANiFe / 1000 ACoCr.
Pt / 100 A carbon 1.8 inch diameter vertical disk, recording density 100 kFCI (4 kbit / mm), relative speed 3
Reproduction output of 200μV at m / sec, minus 30d
The overwriting characteristics of B were obtained. In this embodiment, ρ1 / ρ3 = 5 and ρ2 / ρ1 = 10.

Comparative Example 1 A conventional perpendicular magnetic inductive reproducing head having the structure shown in FIG. Example 1
The process was performed under the same conditions except that the magnetic field detection layer and the lead layer were omitted. Example 1 with 36 turns of coil
3 times the number of turns was formed. When measured under the same conditions as in Example 1, only a low output value of 50 μV was obtained.

( Reference Example ) A head using a NiFe thin film having a specific resistance of 20 μΩcm as a main magnetic pole magnetic material in the first embodiment is used as a reference example . In this case, since the specific resistance of the main magnetic pole is lower than that of the magnetic artificial lattice film serving as the magnetic field detecting layer, a layer for the purpose of insulation is required. A 0.1 μm alumina film was used as an electric insulating layer with the magnetic field detecting layer. The upper yoke and the like are exactly the same as in the first embodiment. An output of 195 μV was obtained by the same measurement as in Example 1. (Comparative Example 2)
A head having 0.7 A / dm ² for 2 minutes is referred to as Comparative Example 2.
You. The part of the upper yoke that is in electrical contact with the magnetic field detection layer
The specific resistance ρ2 of the magnetic field detection layer is 75 μΩcm
3 times 2.5. Measured under the same conditions as in Example 1.
In Comparative Example 2, only a low value of 10 μV or less was obtained.
Did not.

[0039]

[0040]

[0041]

Fourth Embodiment A head in which a return yoke and an upper yoke are made of a permalloy plating film (specific resistance ρ2 = 20 μΩcm) will be referred to as a fourth embodiment. Plating bath is Example 1
An ordinary permalloy plating bath was used except that tartaric acid and ammonium molybdate were removed from the bath. However, instead of reducing the current value at the end of the upper yoke film formation, reverse electrolysis with a current density of -0.1 A / dm ² was applied for 5 minutes. Everything else is the same as in the first embodiment. Although it was difficult to measure the specific resistance of the reverse electrolysis layer, it was 20
It was estimated to be about 0 μΩcm. This head has a reproduction output of 140 μV and an overwrite characteristic of minus 30 dB.

As described above, in the embodiment of the present invention, high reproduction output and writing characteristics were obtained, and the effect of the present invention was confirmed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a perpendicular magnetic head according to the present invention.

FIG. 2 shows a sectional view of another example of the perpendicular magnetic head of the present invention.

FIG. 3 is a sectional view of a conventional perpendicular magnetic head.

FIG. 4 is an enlarged view of the vicinity of a main magnetic pole in a cross-sectional view of the perpendicular magnetic head of the present invention.

FIG. 5 shows a relationship between molybdenum content in a film and specific resistance by an electroplating method.

[Explanation of symbols]

Reference Signs List 1 Base film 2 Return yoke lower film 3 Upper yoke film 3 'Upper yoke film uppermost layer 4 Insulating layer 5 Coil 6 Main pole 7 Magnetic field detecting layer 8 Insulating layer a1 Flow of magnetic flux from the medium in the main pole is conceptually shown. A2 Conceptually showing the flow of magnetic flux through the magnetic field detection layer a3 Conceptually showing the magnetic flux flowing through the upper yoke without passing through the magnetic field detection layer

────────────────────────────────────────────────── ─── Continuation of the front page Examiner Shin Baba (56) References JP-A-60-115014 (JP, A) JP-A-62-262213 (JP, A) JP-A-6-236526 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 5/31 G11B 5/39 G11B 5/129

Claims (6)

(57) [Claims] 1. A perpendicular magnetic head having a magnetic field detection layer formed between a main pole and an upper yoke magnetically coupled to the main pole, wherein the magnetic field detection layer is electrically connected to the main pole. Ρ1, the specific resistance of the portion of the upper yoke that is in electrical contact with the magnetic field detection layer is ρ2, and the specific resistance of the magnetic field detection layer is ρ3 . ρ
3. A perpendicular magnetic head, wherein the length is 3 times or more and 15 times or less. 2. The method according to claim 1, wherein the upper yoke is an alloy film formed by an electroplating method, and a specific resistance of a surface portion of the upper yoke that is in electrical contact with the magnetic field detection layer is higher than that of an inner portion. 2. The perpendicular magnetic head according to claim 1, wherein the height is also higher. 3. The upper yoke is an alloy film containing NiFeMo as a main component formed by an electroplating method, and the Mo content of a surface portion of the upper yoke that is in electrical contact with the magnetic field detection layer is: 3. The perpendicular magnetic head according to claim 1, wherein the vertical magnetic head is higher than a lower portion. 4. The upper yoke is an alloy film formed by an electroplating method, and a film of a surface portion of the upper yoke that is in electrical contact with the magnetic field detection layer is formed by reverse electrolysis. The perpendicular magnetic head according to claim 1 or 2, wherein: 5. The perpendicular magnetic head according to claim 1, wherein the magnetic field detecting layer is a giant magnetoresistive film. 6. The perpendicular magnetic head according to claim 1, wherein the magnetic field detecting layer is a Hall element.