JPH0887715A - Perpendicular magnetic head - Google Patents

Abstract

PURPOSE: To obtain a perpendicular magnetic head which facilitates positioning of a head for reproduction and has a high writing capacity and large reproduced output. CONSTITUTION: A magnetic field detecting layer is formed between the main magnetic pole part of the perpendicular magnetic head and the yoke magnetic layers magnetically coupled to the main magnetic pole part. More preferably, the magnetic head is designed in such a manner that ρ1 and/or ρ2 is made >=3 times ρ3 when the specific resistance of the part of the main magnetic pole magnetic film in electrical contact with the magnetic field detecting layer is defined as ρ1, the specific resistance of the part of the yoke magnetic layer in electrical contact with the magnetic field detecting layer as ρ2 and the specific resistance of the magnetic field detecting layer as ρ3. Positioning is facilitated by commonly using the main magnetic pole of the perpendicular magnetic head for reproducing and writing. Further, a magnetic field detecting part is inserted between the main magnetic pole part and a upper yoke part. In addition, at least the one surface, preferably both surfaces, of the magnetic flux inflow part of the magnetic field detecting part are insulated by magnetic films having the sufficiently large specific resistance of >=3 times, more preferably >=5 times the specific resistance of thc magnetic field detecting layer in order to rapidly effect the magnetic flux inflow to the magnetic field detecting part, by which the high writing capacity and the large reproduced output are obtd.

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 installed in a magnetic disk device for recording and reproducing digital information. In particular, the present invention relates to a perpendicular magnetic head that can handle high density recording because it can obtain a reproduction signal that is significantly larger than that of a conventional inductive head.

[0002]

2. Description of the Related Art IEEE Trans. Magn, MAG-13 (197
7), page 1272, the perpendicular magnetic recording is a recording method in which the magnetic recording medium is magnetized in the in-plane perpendicular direction and is compatible with a high recording density.

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

On the other hand, in the horizontal magnetic recording which is widely used at present, Technical Report of MR92-61 (1992), 7
As in pages, magnetoresistive effect reproducing heads (MR heads) have begun to be used in order to obtain higher reproducing output in high density recording.

Obtaining a reproduction signal by using an MR element in a perpendicular magnetic head is disclosed in Japanese Patent Laid-Open No. 4-278210, but since the main magnetic pole is divided by the MR element, writing is performed. It was not possible to generate a large magnetic field, and it was read-only.

The MR element of the magnetic head is disclosed in Japanese Patent Laid-Open No. 4-182.
As in Japanese Patent No. 913, a structure is also proposed in which the magnetic flux flows perpendicular to the film surface. However, as described in the specification, NiFe is used as a magnetoresistive effect element.
It is obvious that the case where is used is more disadvantageous than the structure in which the magnetic flux flows in the film surface direction. Also, since it is a normal horizontal recording head, its effect is small. On the other hand, in the same way, the structure in which the magnetic flux flows perpendicular to the film surface is Hall
A magnetic head using an element has been proposed. In this case, because of the Hall effect, even if the magnetic flux flows perpendicularly to the film surface, the magnetic flux can be detected with high efficiency.

As described above, various magnetic head structures have been reported, but the reproduction efficiency of the perpendicular magnetic head is further improved.
There has been a big problem with the MR magnetic head in which the two main magnetic poles are shared for reproduction and writing.

[0008]

The MR composite magnetic head for further enhancing the reproducing efficiency of the perpendicular magnetic head is required to have a structure different from that of a normal horizontal recording MR head. That is, because of the extremely high density, the film thickness of the write main pole is as thin as 0.5 μm or less, and positioning is extremely difficult to read by the 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 for passing a current through the MR element, the magnetic field during writing becomes insufficient.

[0009]

[Means for Solving the Problems] Such perpendicular magnetic MR
It is possible to solve various problems of the head and obtain a high reproduction signal by the following invention.

(1) A perpendicular magnetic head characterized in that 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 electrically contacting the magnetic field detection layer is ρ1, the specific resistance of the portion of the yoke magnetic layer electrically contacting the magnetic field detection layer is ρ2, the magnetic field detection layer. The perpendicular magnetic head according to (1) above, wherein ρ1 and / or ρ2 is 3 times or more of ρ3, where ρ3 is the specific resistance of ρ3.

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

(4) The yoke magnetic layer is an alloy film containing NiFeMo as a main component 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 outermost 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 the above (1) to (5), wherein the magnetic field detecting layer is a giant magnetoresistive film.

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

[0017]

In the present invention, the 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, preferably both sides, of the magnetic flux detecting section of the magnetic field detecting section is detected in order to promptly flow the magnetic flux into the magnetic field detecting section. Insulation with a magnetic film having a sufficiently large specific resistance of 3 times or more, preferably 5 times or more, of the specific resistance of the layer makes it possible to obtain high writing ability and large reproduction output.

[0018]

[Specific Structure] 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 magnetic pole, 3 is the upper yoke film, and 2
Is a film under the return yoke. Main magnetic pole part is permalloy, NiFeMo, FeN, FeYO, FeHfO, C
It is preferable to use a soft magnetic material such as oZr.

Further, a multilayer high resistance soft magnetic material as disclosed in JP-A-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 detecting layer, the insulating layer for the purpose of insulation is not necessary between the main magnetic pole and the magnetic field detecting layer. When a material having a low specific resistance such as permalloy is used, it is necessary to provide an insulating layer having a high specific resistance with the magnetic field detection layer. A non-magnetic material such as alumina can be used as the insulating layer, 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 the permalloy film, but it is also easy to increase or decrease the molybdenum content in the film by changing the current density during film formation. When the molybdenum content in the film is increased, the soft magnetic characteristics are slightly deteriorated, but the specific resistance of the film is remarkably increased 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. Even when a permalloy film is used, it is possible to obtain the same insulating effect by performing reverse electrolysis to dissolve the permalloy plating layer on the surface and form a layer having a high specific resistance with a high sulfur oxygen content. is there.

Recording is performed by applying a current to the coil of 5 to cause a magnetic flux to enter the external recording medium from the tip of the main magnetic pole 6 and magnetize it. At this time, if the main magnetic pole is divided halfway, a strong magnetic field cannot be generated, the medium cannot be magnetized sufficiently, and the overwrite characteristics and the like deteriorate. Therefore, it is not preferable to divide the main magnetic pole in order 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 much higher sensitivity to a magnetic field than the conventional anisotropic magnetoresistive effect such as permalloy, so that a sufficient reproduction output can be obtained even when a 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 with a thickness on the order of atomic diameter of metal are periodically stacked, and has characteristics different from those of 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 of iron-chromium type, cobalt-copper type, etc. have been known so far. Has been. Of these, iron-chromium type (Fe
/ Cr) is 40 at ultra low temperature (4.2K)
There is a report that it shows a magnetoresistance change exceeding 100% (Phy
s. Rev. Lett Vol. 61, page 2472, 1988.
Year).

However, in this artificial lattice magnetic multilayer film, the external magnetic field (operating magnetic flux strength) at which the maximum resistance change occurs is more than ten kOe.
~ Large at several tens of kOe, and it is not practical as it is. In addition, artificial lattice magnetic multilayer films of Co / Ag and the like have been proposed, but the operating magnetic field strength of these is too large.

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

In this structure, two NiFe layers are formed via a non-magnetic layer, and FeMn is 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 the exchange coupling force, the magnetic spin of this NiFe layer is several tens to several hundreds.
The direction is fixed up to the magnetic field strength of Oe. One Ni
The spin of the Fe layer can freely change its direction 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, which is about the coercive force of the NiFe layer.

Further, since the Hall element can effectively detect the magnetic flux component perpendicular to the surface, a high reproduction signal can be obtained even in the magnetic head of this structure. InSb as a Hall element,
Materials such as InAs and GaSs can be used.

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

If the specific resistance of the electric insulating layer is 3 times or more, and particularly preferably 5 times or more the specific resistance of the magnetic field detecting layer, a decrease in detection sensitivity due to shunting can be prevented. If the specific resistance is less than 3 times, the effect of shunt current 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 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 detection layer. The shunt of the electric current affects not only the specific resistance of the film but also the film thickness. However, when laminating thin films, the effect of the resistance at the interface between the films is large, and the specific resistance of the film itself has a large effect on this interface resistance. Therefore, by defining the specific resistance of the film, the desired effect can be obtained. can get.

The resistance at the interface between the layers is a heavy electric insulation layer. The electric insulation layers must be provided on both sides of the magnetic field detection layer. However, it is also possible to give the main magnetic pole itself the same effect as the electrical insulating layer, and in this case, it is sufficient to form it only on the upper yoke side as shown in FIG. Further, as shown in FIG. 2, when a molybdenum permalloy film or the like is used as the material of the upper yoke and the specific resistance of the uppermost layer is set to 3 times or more, particularly preferably 5 times or more of the specific resistance of the magnetic field detection layer, the uppermost layer is substantially formed. In order to function as an electric insulation layer, it is possible to continuously form a plating film from the same apparatus and the same plating bath. As described above, the electric insulating layer in the present invention is a magnetic film having a specific resistance three times or more that of the magnetic field detecting layer, which is effectively used for insulating the upper and lower portions of the magnetic field detecting layer, and not only the insulating but also the magnetic flux induction effect. It is preferable to use a material that can also be expected on at least one side.

The molybdenum permalloy plating film contains tartaric acid or its salt in an amount of 0.1 mol / mol in an ordinary permalloy plating bath.
A film can be formed by adding an appropriate amount of 1 to 1 mol / l of ammonium molybdate ion. The bath temperature during film formation is from 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 molybdenum ion content in the bath is constant, the molybdenum content in the film increases as the current density during film formation decreases. That is, in the upper yoke film forming step, a high permeability molybdenum permalloy film having a molybdenum content of 2 to 5 wt% is usually used for 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 reducing the current density and performing electrodeposition for a short time. There is no problem if the thickness of the high resistivity molybdenum permalloy layer as the electric insulating layer is 500 A or more.

In order to obtain a high resistivity layer by reverse electrolysis of the permalloy plating film, reverse electrolysis is applied at the final stage of ordinary film formation. The amount of reverse electrolysis is 0.01 to 0.2 ampere hour, and the current density is 0.01 A / dm ² to 1 A / dm ² . The bath voltage rises when the reverse voltage is applied, so
It is preferable to make the determination while looking at the bath voltage.

[0032]

EXAMPLES Examples of the present invention and comparative examples will be described in detail below. Example 1 An example of the head structure of the present invention will be shown as Example 1. In the structure shown in FIG. 2, the main magnetic pole 6 is formed of a FeYO film having a specific resistance of 150 μΩcm and a magnetic permeability of 1500 formed by a sputtering method, and the protrusion amount from the upper yoke having a thickness of 0.1 μm, a width of 10 μm and 3 is 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.
And each of them is a molybdenum permalloy film formed by electroplating and the specific resistance ρ is 60μ at a molybdenum content of 4 wt%.
It was 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 300μ
It was Ωcm. As the magnetic field detection layer, an induction ferrimagnetic artificial lattice film formed by the MBE method and having a specific resistance of 30 μΩcm was used.

On the substrate, an alumina film 10 is sputtered on a 0.5-inch thick 3-inch ALTIC.
A film having a thickness of μm was used. The return yoke part uses a bath of the following composition by electroplating with a current density of 1 A / dm ² ,
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 / liter Iron sulfate 0.015 mol / liter Boric acid 0.4 mol / liter Ammonium chloride 0.25 mol / liter Saccharin 2 g / liter Potassium sodium tartrate 0.5 mol / liter Membrane composition Was 79 wt% Ni-17 wt% Fe-4 wt% Mo. A novolac photoresist was used as an insulating material for the magnetic core, and a 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, but the current density was reduced to 0.1 A / dm ² only for the last 5 minutes.

The magnetic field detecting portion was formed by depositing 50 A of Cr and using it as an underlayer to form NiFe (50) -Cu (50) -Co.
(50) -Cu (50) -NiFe (50) was sequentially laminated twice to form a magnetic multilayer film. The film forming conditions are
Ultimate pressure 1.3 × 10 ^-10 Torr, film formation pressure 1.2 × 1
0 ^-9 Torr, and the substrate temperature was 35 ° C. C., the materials 0.2
The 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 the film formation rate of 0.3 A / sec. After that, a pattern of 20 μm × 6 μm is formed, an electrode having a track width of 3 μm is formed on the pattern, and then a film of the main magnetic pole is formed by rf sputtering in an argon atmosphere with oxygen of 0.2 to 0.
About 5% by volume was included to form a film. 78 at% Fe-9 at
% Y-13 at% O film composition. Finally, after forming a photoresist insulating layer, a coil layer, an alumina protective film, etc., the head piece was machined and assembled into 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 vertical disk is used, recording density 100 kFCI (4 kbit / mm), relative speed 3
200 mV playback output at m / sec, minus 30 d
The overwrite property of B was 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 trial production was performed under the same conditions except for the process in which the magnetic field detection layer and the lead layer were omitted. The number of turns of the coil is 36, and the first embodiment is used.
3 times the number of turns. When measured under the same conditions as in Example 1, the reproduction output was as low as 50 μV, which was a low value.

Example 2 A head using a NiFe thin film having a specific resistance of 20 μΩcm as the main magnetic pole magnetic material in Example 1 will be referred to as Example 2. In this case, the specific resistance of the main pole is lower than that of the magnetic artificial lattice film, which is the magnetic field detection layer, so that a layer for insulation is required. An alumina film having a thickness of 0.1 μm was used as an electric insulation layer for the magnetic field detection layer. The upper yoke and the like are exactly the same as in the first embodiment. The same measurement as in Example 1 gave an output of 195 μV.

Comparative Example 2 A head in which the last two minutes of forming the upper yoke film was 0.7 A / dm ^{2 in} Example 1 is referred to as Comparative Example 2. The specific resistance ρ2 of the portion of the upper yoke in electrical contact with the magnetic field detection layer was 75 μΩcm, which was 2.5 times the specific resistance ρ3 of the magnetic field detection layer. When measured under the same conditions as in Example 1, in Comparative Example 2, only a low value of 10 μV or less was obtained.

<Example 3>, <Comparative Example 3> The basic structure is the same as that of Example 1, and In is used as a magnetic field detection layer.
A Hall effect head using an Sb film was prototyped. InS
Since the film b has a large specific resistance of 600 μΩcm, 0.1 μm alumina layers were formed above and below the magnetic field detection layer. However, since the Hall effect element has a particularly high magnetic field detection sensitivity in the vertical direction, a good reproduction output of 150 μV was obtained.

Next, when a head using a hard film bias type permalloy film having a CoPt thin film as a hard layer and a magnetic field detecting layer is set as Comparative Example 3, this head has a reproduction output of 50 μm.
I could only get V.

<Embodiment 4> A head in which the return yoke and the upper yoke are made of a permalloy plating film (specific resistance ρ2 = 20 μΩcm) is referred to as Embodiment 4. The plating bath is Example 1
An ordinary permalloy plating bath from which tartaric acid and ammonium molybdate were removed was used. 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 Example 1. It was difficult to measure the specific resistance of the reverse electrolysis layer, but it was 20 from comparison with the sample without reverse electrolysis.
It was estimated to be about 0 μΩcm. This head has a reproduction output of 140 μV and an overwrite characteristic of -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 drawings]

FIG. 1 shows a sectional view of an example of a perpendicular magnetic head of 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 the main pole of a sectional view of a perpendicular magnetic head of the present invention.

FIG. 5 shows the relationship between the molybdenum content in the film and the specific resistance obtained by electroplating.

[Explanation of symbols]

1 Underlayer 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 detection layer 8 Insulating layer a1 Magnetic flux flow from the medium in the main pole was conceptually shown. Thing a2 conceptually showing the flow of magnetic flux through the magnetic field detection layer a3 conceptually showing magnetic flux flowing through the upper yoke without passing through the magnetic field detection layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Sato 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation

Claims (7)

[Claims] 1. A perpendicular magnetic head comprising a magnetic field detecting layer formed between a main magnetic pole and a yoke magnetic layer magnetically coupled to the main magnetic pole portion. 2. A resistivity of a portion of the main magnetic pole magnetic film electrically contacting the magnetic field detecting layer is ρ1, a resistivity of a portion of the yoke magnetic layer electrically contacting the magnetic field detecting layer is ρ2, and a resistivity of the magnetic field detecting layer is When the specific resistance is ρ3, ρ1 and / or ρ2 is ρ3
3. The perpendicular magnetic head according to claim 1, wherein the perpendicular magnetic head is 3 times or more than. 3. The upper yoke magnetic layer is an alloy film formed by an electroplating method, and the specific resistance of the film of the alloy film surface layer is higher than that of an inner part thereof. Item 3. The perpendicular magnetic head according to Item 1 or 2. 4. The yoke magnetic layer is an alloy film containing NiFeMo as a main component formed by an electroplating method, and the Mo content of the film on the outermost surface of the upper yoke is lower than that on the lower side. 4. The perpendicular magnetic head according to claim 1, wherein the height is high. 5. The yoke magnetic layer is an alloy film formed by an electroplating method, and the film on the outermost surface of the upper yoke is formed by reverse electrolysis.
The perpendicular magnetic head according to any one of 1. 6. The perpendicular magnetic head according to claim 1, wherein the magnetic field detection layer is a giant magnetoresistive film. 7. The magnetic field detection layer is a Hall element.
6. The perpendicular magnetic head according to any one of 1 to 5.