JPH083883B2 - Thin film magnetic head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head suitable for high density magnetic recording, and more particularly to a thin film magnetic head having good writing characteristics.

[Conventional technology]

The thin film magnetic head is composed of a coil, an insulating layer and a magnetic pole formed on a substrate by a semiconductor process. That is, as shown in FIG. 2 showing the vertical cross-sectional structure of the thin film magnetic head, the insulating layer 2 is laminated on the lower magnetic film layer 1. An insulating layer 3 containing a plurality of coils 5 is formed on the insulating layer 2.
Are stacked. An upper magnetic film layer 6 is laminated on the insulating layer 3. As the magnetic film applied to the thin film magnetic head magnetic pole, a Ni ₈₁ Fe ₁₉ (permalloy) alloy having a thickness of 1 to 2 μm is generally used. Permalloy has the advantages that it has a small magnetostriction constant λs, it is easy to impart uniaxial anisotropy, the coercive force H _CH in the difficult axial direction can be set to 1 oersted or less, and the chemical and thermal stability are good. On the other hand, the saturation magnetic flux density B _S of permalloy is about 10,000 gauss, and there is a limit to decrease the thickness of the thin film magnetic head magnetic pole and increase the recording density. That is, the write magnetic field 9 is reduced by reducing the thickness t _g1 and t _g2 of the lower magnetic film thickness 1 and the upper magnetic film layer 6 of the thin film magnetic head shown in FIG.
The recording density can be increased by making the spatial distribution of the recording medium sharp and the length of the recording bit 11 written on the recording medium 12 short, but the writing magnetic field strength decreases. To compensate for this, the current flowing through the coil 5 is increased, but in Permalloy, as described above, B _S is low and the magnetic pole is saturated, so that the write magnetic field is not sufficiently generated. Was but connexion, high saturation magnetic flux density in the magnetic pole portions amorphous Co-based alloy (B _S = 13000~15000 gauss), crystalline
It is conceivable to apply the Fe-based alloy (B _S = 18000~21000 gauss) or the like. However, amorphous Co-based alloys have problems with thermal stability, and crystalline Fe-based alloys have problems with corrosion resistance.
These issues have not yet been resolved.

Feromagnetism (RMBozorth, Van N, by Hosors, published by Juan Nostrand, 1951)
ostrand1951) pp. 165 and 675, Co-Fe-Ni
It is clear that there is a region where the magnetostriction constant is almost zero and the saturation magnetic flux density is 12000 Gauss or more in the Co main component region in the ternary phase diagram. However, the alloy system in this region has a large magnetic anisotropy constant K ₁ (up to 10 ⁴ erg / cm ³ ), and even if the alloy is used as it is as a magnetic head magnetic pole, the magnetic permeability is low and it is not practical. Conventionally, in order to increase the magnetic permeability, for example, I E E E Transaction on Magnetics MGS 13,1521 (1
977) As shown in IEEE, Trans.Magn.MAG-13,1521 (1977), by using a dielectric material such as Permalloy and Al ₂ O _{3 to} form a multilayer film, and processing it into a strip shape with a width of several 10 μm, It is known that the magnetic susceptibility increases in the high frequency range. This is because the energy loss due to the eddy current generated in the permalloy at the time of high frequency excitation is reduced due to the limitation of the dimensional shape such as thinning and strip processing. Therefore,
A CoNiFe-based metal, which is essentially anisotropic, does not improve the magnetic susceptibility even if it is multilayered as it is. On the other hand, I.E.E.Transaction of Magnetics M.A.G. 166 (1961), IEEE, Trans.Magn.MAG
According to -1,66, (1961), by applying alternating and alternating magnetic fields to the substrate during the deposition of permalloy,
It is known that the uniaxial anisotropy constant of permalloy can be controlled. An example in which this is applied to a shape of a CoNiFe alloy by an electrodeposition method is disclosed in JP-A-61-76642.
According to this conventional example, the anisotropic magnetic field H _K of the CoNiFe alloy is about
It is reduced to 1/6.

Also, forming a CoNiFe alloy by a method such as vacuum deposition is disclosed in Japanese Patent Publication No. 60-82638.

[Problems to be solved by the invention]

However, in the conventional example described in the above-mentioned JP-A-61-76642, the magnetic film formed by the electrodeposition method is deteriorated in magnetic characteristics by the heat treatment that the film receives during the thin film magnetic head forming process. There is a drawback that the coercive force increases.

Further, when the substrate temperature is 350 ° C. and the film deposition rate is 18 Å / sec, which are the formation conditions described in Japanese Patent Publication No. Sho 62-82638, the coercive force of a high Co region having a high saturation magnetic flux density, that is, an alloy having a Co concentration of 70 wt% or more Can not be lowered.

That is, in the above-mentioned prior art, CoFe or CoNiFe alloy having a high saturation magnetic flux density is not considered in terms of high permeability, that is, a small coercive force is formed, and to use these alloys as a magnetic pole for a thin film magnetic head, There were difficulties.

In order to solve such problems, the present invention provides the above
It is an object of the present invention to provide a thin film magnetic head having good reproduction characteristics, which is formed of CoFe or CoNiFe alloy having a small coercive force.

[Means for solving problems]

Before describing the means for solving the problems, the background of the completion of the present invention will be described.

The sputtering method is known as a means for realizing a magnetic thin film having good heat resistance. We have a Co concentration of 70%
An attempt was made to form a sputtering film on a glass substrate using the above CoNiFe alloy as a cathode. As a result, the spattering film with a thickness of about 1 μm applied to the thin film magnetic head magnetic pole has a large coercive force Hc of 300e even if the alloy composition is changed or the spattering power and Ar gas pressure are changed. No uniaxial magnetic anisotropy was also induced. However, it was found that the coercive force H _{CH in} the hard axis direction sharply drops below 0.5 μm when the sputtering film thickness is reduced. Also, the substrate temperature at the time of spattering can be controlled by the film surface.
By keeping the temperature below 100 ° C., the coercive force in the difficult axis direction could be reduced to 20 e or less even with a film thickness of 1 to 1.5 μm.

That is, in the alloy film or the film having a small film thickness formed by keeping the substrate temperature low, the average crystal grain size can be 0.06 μm or less. As a result, it is considered that the coercive force in the hard axis direction was lowered.

The present invention has been made based on such knowledge, and the content thereof is that a first insulating layer is provided on a substrate, and a lower magnetic film layer, a second insulating layer and an upper magnetic film layer are provided on the insulating layer. In a thin-film magnetic head having a coil in which the lower and upper magnetic film layers are in contact with each other at one portion and winding the same portion in a second insulating layer, a part or all of the magnetic film layer is a magnetic alloy. A thin-film magnetic head made of CoFe or CoNiFe, wherein the average grain size of the magnetic alloy is 0.06 μm or less.

In the present invention, the average value of the crystal grain size of the magnetic alloy is
The following methods are available as methods for reducing the thickness to 0.06 μm or less. First, there is a method in which a magnetic alloy layer is formed by a sputtering method and the substrate temperature during film formation is set to 100 ° C. or lower. In addition, the thickness of the magnetic alloy layer is 0.5 μm or less, and another metal alloy or dielectric is sandwiched between the magnetic alloy layers to form a multilayer structure.

It was found that a thick CoNiFe alloy film with a low coercive force can be obtained by this method. This method is advantageous for forming a CoNiFe film by using a mass-production type sputtering device in which the substrate cannot be cooled.

The composition of the CoNiFe alloy or the CoFe magnetic alloy in the present invention is 0 ≦ x ≦ 2 when expressed as Co _100-XFY Ni _X Fe _Y.
0 and ≦ y ≦ 10.

[Action]

The relationship between the average crystal grain size of the CoNiFe or CoFe magnetic alloy layer and the coercive force is shown in FIG. 1, and the relation between the substrate temperature and the average crystal grain size of the magnetic alloy layer is shown in FIG. The relationship between thickness and coercive force is shown in FIG.

As can be seen from FIG. 1, the coercive force can be significantly reduced when the crystal grain size is 0.06 μm or less. The reason why the coercive force of the magnetic alloy film is lowered by setting the crystal grain size to 0.06 μm or less will be described.

It is known that the magnetization of a polycrystalline magnetic alloy is the sum of minute magnetizations that vary for each crystal substance along the average easy axis direction. To rotate the average magnetization direction of this alloy,
When an external magnetic field is applied, the individual crystal grains turn their stable magnetization due to their crystal orientation to a direction with higher energy. This easiness of rotation is expressed by the magnetocrystalline anisotropy energy K _1, which is a high Co concentration Co.
The K ₁ of NiFe or CoFe alloy is 10 ⁴ to 10 ⁵ erg / cm ³ and 100 to 1000 times that of permalloy (10 ² erg / cm ³ ). In a coarse crystal grain and a fine crystal grain having the same volume as that of the coarse crystal grain, the crystal orientations between the crystal grains are different, so that the magnetic anisotropy energy is lowered. That is, the finer the crystallite diameter, the smaller the individual magnetocrystalline anisotropy. It is considered that this is the reason why a low coercive force in the hard axis direction can be realized only with a CoNiFe or CoFe film having a small crystal grain size.

By setting the average crystal grain size to 0.06 μm or less, heat resistance is improved. As a result, during the thin film magnetic head forming process,
The magnetic properties do not deteriorate due to the heat treatment that the film receives,
The coercive force does not increase. This is because grain growth does not occur if the average crystal grain size is sufficiently small.

Next, regarding the relationship between the substrate temperature and the average crystal grain size,
As shown in FIG. 3, in the alloy film formed while the substrate temperature was kept low (100 ° C. or less), the average crystal grain size was 0.06
It can be seen that the thickness is less than μm.

Next, regarding the relationship between the film thickness and the coercive force, as shown in FIG. 4, it can be seen that the coercive force is small when the film thickness is 0.5 μm or less. This is for the following reason. It was found that when a thick CoNiFe alloy film was formed at a high substrate temperature, the crystal grain size in the film thickness direction was fine on the substrate side and coarsened toward the film surface. Therefore, from the relationship between the film thickness and the coercive force shown in FIG. 4, the film thickness may be set to 0.5 μm or less. In this case, another metal, alloy, or dielectric can be sandwiched between the magnetic alloy layers to form a multilayer film. The reason why the coercive force is lowered by forming a multilayer film is considered to be due to the effect that the grain size of the magnetic layer is made 0.06 μm or less by cutting off the growth of CoNiFe crystal grains by another layer.

〔Example〕

Examples of the present invention will be described below. In Table 1,
The sputtering conditions for CoNiFe alloys are shown below.

The CoNiFe sputtering film formed under the above conditions was used as the first layer, and NiFe, Al ₂ O ₃ and SiO ₂ were used as the second layer to form a laminated film, and the magnetic properties thereof are shown in each film thickness and each table.

In the table, NiFe, Al ₂ O ₃ and SiO ₂ were all sputtered in the same sputtering device as CoNiFe using another cathode. This condition is shown in Table 3.

According to this embodiment, the saturation magnetic flux density is 1000 permalloy.
CoNiFe multi-layer film with a coercive force larger than 0 Gauss) and a small coercive force was obtained.

Another embodiment of the present invention will be described. When the substrate was water-cooled and sputtered under the conditions shown in Table 1, the results shown in Table 4 were obtained. The substrate temperature at this time is 50-60
It was ℃.

According to this example, it is found that the film thickness is 0.5 μm or less and the coercive force is small.

Further, a third embodiment of the present invention will be described.

CoNiFe alloy (layer thickness 0.1μm) and A formed according to Table 1
l ₂ with O ₃ (the layer thickness 0.01 [mu] m) multilayer film (thickness 1.1 .mu.m) as the magnetic pole, and a thin film magnetic head having the structure shown in FIG. 2, whereas the thin-film magnetic using permalloy (thickness 1.1 .mu.m) Heads were prepared and their recording and reproducing characteristics were compared. A γ-Fe ₂ O ₃ film was used as the recording medium. The thin-film magnetic head manufactured using the multi-layer film has a reproduction output after recording of about 1.3 times that of the one using Permalloy. It can be seen from this example that a thin film magnetic head with improved resolution can be manufactured by reducing the magnetic pole thickness.

Further, a fourth embodiment of the present invention will be described. When the CoNiFe alloy according to Table 1 was produced, magnetic fields were sequentially applied to the substrate in directions orthogonal to each other to form a film. The conditions are shown in Table 5.

By this sputtering in the switching magnetic field, CoNiFe
The anisotropic magnetic field of the alloy can be reduced from 20 to 12 ersted, and the permeability of the film alone can be improved.

〔The invention's effect〕

As described above, according to the present invention, a magnetic thin film having a higher saturation magnetic flux density, a smaller coercive force, and better heat resistance than a permalloy single-layer film can be produced. There is an effect that it is possible to provide a thin film magnetic head for high recording density magnetic recording which has a high reproducing characteristic.

[Brief description of drawings]

Figure 1 is a graph showing the relationship between CoNiFe crystal grain size and coercive force.
Fig. 2 is a vertical cross-sectional view of the thin film magnetic head and a diagram showing the recording / reproducing principle. Fig. 3 is a graph showing the relationship between crystal grain size and substrate temperature. Fig. 4 is a graph showing the relationship between CoNiFe film thickness and coercive force. Is. 1 ... lower magnetic film layer, 2 ... gear part, 5 ... coil, 6 ... upper magnetic film layer, 9 ... write magnetic field, 10 ... recording magnetic field from medium, 12 ... recording medium.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Narishige 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki 4026, Hitachi Research Institute, Ltd. (72) Koichi Nishioka 4026 Kuji Town, Hitachi City, Ibaraki, Hitachi, Ltd. In Hitachi Research Laboratory (72) Inventor Masanobu Kazono 4026 Kujicho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Inventor Tetsuo Kobayashi 2880 Kokuzu, Odawara City, Kanagawa Hitachi Ltd. Odawara Factory ( 56) References JP-A-62-287410 (JP, A) JP-A-62-243108 (JP, A) JP-A-62-158306 (JP, A)

Claims (1)

[Claims] 1. A first insulating layer on a substrate, a lower magnetic film layer, a second insulating layer and an upper magnetic film layer are sequentially stacked on the insulating layer, and the lower and upper magnetic film layers are partially formed. In a thin film magnetic head having a coil in contact with and winding the same portion in a second insulating layer, a part or all of the magnetic film layer is made of CoFe or CoNiFe which is a magnetic alloy, and a crystal of the magnetic alloy. A thin-film magnetic head having an average grain size of 0.06 μm or less.