JP2570337B2 - Soft magnetic laminated film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic laminated film, and more particularly, to a soft magnetic laminated film used as a core of a magnetic head exhibiting performance suitable for high-density recording.

[Summary of the Invention]

The present invention relates to a soft magnetic laminated film used as a core of a magnetic head and the like, in which a main magnetic layer made of pure Fe or a crystalline magnetic alloy thin film containing Fe as a main component and an intermediate film made of an amorphous nonmagnetic alloy thin film are used. By laminating the layers, a soft magnetic laminated film having a high saturation magnetic flux density and excellent heat resistance is provided.

[Conventional technology]

For example, in a magnetic recording / reproducing device such as an audio tape recorder or a VTR (video tape recorder),
Higher density and higher quality of recording signals are progressing, and so-called metal tape using ferromagnetic metal powder such as iron as magnetic powder, or ferromagnetic metal material is directly coated on base film by vacuum thin film forming technology. A so-called deposited tape or the like that has been put on the market has been put to practical use.

By the way, in order to make good use of the characteristics of a magnetic recording medium having such a high coercive force to perform good recording and reproduction, the core material of the magnetic head must have a high saturation magnetic flux density and the same magnetic head. In the case where reproduction is to be performed, it is required to additionally have high magnetic permeability.

Various soft magnetic laminated films have been proposed as materials meeting such demands. As a typical example,
A soft magnetic laminated thin film in which an Fe-based crystalline layer and a Co-based amorphous layer are laminated has been known. Each of these is a soft magnetic material, but we aimed to further improve the soft magnetic properties by combining the high saturation magnetic flux density of the Fe-based crystalline layer and the high magnetic permeability of the Co-based amorphous layer. Things.

Also, a soft magnetic laminated film in which a metal magnetic thin film and an oxide-based non-magnetic thin film are laminated has been proposed.

[Problems to be solved by the invention]

However, the soft magnetic laminated film in which the Fe-based crystalline layer and the Co-based amorphous layer are laminated has the following problems. First, the heat resistance of the soft magnetic laminated film is determined by the crystallization temperature of the Co-based amorphous layer, and the limit is about 500 ° C. in many cases. Secondly, in order to impart soft magnetism to the Co-based amorphous layer, it is necessary to form this layer to a certain thickness, but for this reason, the thickness of the Fe-based crystalline layer relatively decreases,
The saturation magnetic flux density when formed as a laminated film cannot be increased so much. Third, induced magnetic anisotropy is present in the Co-based amorphous layer, which adversely affects the soft magnetic properties of the laminated film.

Further, in a soft magnetic laminated film in which a metal magnetic thin film and an oxide-based non-magnetic thin film are laminated, characteristics such as a thermal expansion coefficient and an etching rate of both the thin films are too different, and peeling and workability between the thin films are low. It is the cause of that.

Therefore, an object of the present invention is to provide a soft magnetic laminated film having improved heat resistance and soft magnetic characteristics.

[Means for solving the problem]

The soft magnetic laminated film according to the present invention has been proposed in order to achieve the above-mentioned object, and comprises a main magnetic layer comprising pure Fe or a crystalline magnetic alloy thin film containing Fe as a main component, and an amorphous non-magnetic layer. An intermediate layer comprising an alloy thin film is laminated.

Here, the material of the main magnetic layer is not only pure Fe but also a crystalline magnetic alloy thin film containing Fe as a main component. Alloys that can be used as the latter materials include, for example, FeSi, Sendust, FeGaSi, FeAlGe,
FeCoSi, FeCoSiAl and the like. The film thickness is selected in the range of 10 to 10,000 °, more preferably 50 to 5000 °.

The material of the intermediate layer is an amorphous nonmagnetic alloy thin film, and alloys that can be used as the material include, for example, CoZr, CoH
f, CoTa, CoNb, NiZr, NiHf, CuZr, CuHf and the like. The film thickness is 3
It is selected in the range of Å1000Å, more preferably 5Å50Å.

The above ranges of the thicknesses of the main magnetic layer and the intermediate layer are set from the viewpoint of optimizing the soft magnetic characteristics of the obtained soft magnetic laminated film. Magnetic properties cannot be expected.

The number of layers of the main magnetic layer and the intermediate layer can be appropriately set according to the desired characteristics of the soft magnetic laminated film.

Sputtering is usually performed to create a soft magnetic laminated film as described above, and various methods such as high-frequency magnetron sputtering, DC sputtering, facing target sputtering, ion beam sputtering, etc. can be applied. It can be performed under normal conditions. At this time, as an evaporation source, an alloy target,
An independent target for each component element, a target in which a small amount of element chips are mounted on a target of an element serving as a main component, or the like can be used.

One or both of the crystalline magnetic alloy thin film and the amorphous non-magnetic alloy thin film containing Fe as a main component may contain 0.1 to 10 atomic% of nitrogen or oxygen. In order to introduce nitrogen or oxygen, these gases may be mixed at an appropriate partial pressure in a sputtering atmosphere mainly composed of argon or the like.

[Action]

The soft magnetic laminated film according to the present invention is formed by laminating a crystalline magnetic alloy thin film containing Fe as a main component and an amorphous nonmagnetic alloy thin film. The heat resistance of such a soft magnetic laminated film is determined by the crystallization temperature of the amorphous non-magnetic alloy thin film, and when the amorphous non-magnetic alloy thin film changes to crystalline, the heat resistance between the amorphous magnetic thin film and the crystalline magnetic alloy thin film is reduced. Diffusion occurs and soft magnetic characteristics deteriorate. However, since the amorphous nonmagnetic alloy thin film used here has a high crystallization temperature, it is advantageous to keep the amorphous state and prevent diffusion between the amorphous magnetic thin film and the crystalline magnetic alloy thin film. With such a configuration, a high saturation magnetic flux density can be obtained. further,
Since the soft magnetic laminated film is formed by joining metals, delamination due to heat hardly occurs, and from such a viewpoint, the heat resistance of the soft magnetic laminated film is improved.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

First, the soft magnetic properties of a soft magnetic laminated film having pure Fe as the main magnetic layer and Co ₅₀ Zr ₅₀ (the number represents atomic%; the same applies hereinafter) were examined. First, using a target of pure Fe and a Co ₅₀ Zr ₅₀ alloy, a pure Fe thin film and Co were simultaneously subjected to dual sputtering in a pure argon atmosphere at a flow rate of 20 SCCM and a gas pressure of 2.5 mTorr.
Each film thickness of ₅₀ Zr ₅₀ alloy thin film are alternately laminated on the glass substrate while changing variously to prepare a soft magnetic multilayer film of total thickness 1.8 .mu.m. At this time, the thickness of each thin film was changed by variously selecting the number of revolutions of the glass substrate or the input power to each target. FIG. 1 shows the results of measuring the soft magnetic characteristics of each soft magnetic laminated film thus obtained immediately after sputtering. In this figure, the vertical axis is pure Fe
Thin film having a film thickness of a (Å), the horizontal axis represents Co ₅₀ Zr ₅₀ alloy thin film thickness (Å), respectively. Each point in the drawing indicates a combination of the measured film thicknesses of the respective soft magnetic laminated films, and solid lines connecting these in a substantially arc shape are iso-Hc lines connecting points having the same coercive force Hc. The dotted line is an iso-Bs line connecting points having the same saturation magnetic flux density Bs.
From this figure, it can be seen that an extremely high saturation magnetic flux density of about 20 kG was obtained in a combination in which the thickness of the Fe thin film was about 10 times the thickness of the Co ₅₀ Zr ₅₀ alloy thin film. Further, in the region where the saturation magnetic flux density Bs is 20 kG or more, the coercive force is high, and some of them reach the level of 10 kG.

Next, FIG. 2 shows the result of examining the relationship between the combination of film thicknesses and the specific resistance at room temperature for the above-described soft magnetic laminated film. In this figure, the vertical axis represents the thickness (Å) of the pure Fe thin film,
The horizontal axis indicates the thickness (Å) of the Co ₅₀ Zr ₅₀ alloy thin film.
Each point in the drawing indicates a combination of the measured film thicknesses of the respective soft magnetic laminated films, and a solid line is an iso ρ line connecting points having the same specific resistance ρ (μΩ · cm). From this figure, relatively Co ₅₀ Zr ₅₀ enough to the thickness of the pure Fe thin relative to the thickness of the alloy thin film increases, the specific resistance is seen that tends to decrease.

Next, a soft magnetic laminated film having pure Fe as a main magnetic layer and Ni ₅₀ Zr ₅₀ as an intermediate layer was prepared, and the soft magnetic properties thereof were examined. The sputtering conditions at the time of formation are the same as in the case of forming the above-described soft magnetic laminated film using Co ₅₀ Zr ₅₀ as the intermediate layer, except that the target of the intermediate layer is changed. The result is shown in FIG. In this figure, the vertical axis represents the thickness (Å) of the pure Fe thin film,
The horizontal axis indicates the thickness (Å) of the Ni ₅₀ Zr ₅₀ alloy thin film.
Other items to be described are the same as those in the above-described respective drawings. Also in this case, a tendency similar to the result shown in FIG. 1 was observed.

Next, an example in which a crystalline magnetic alloy thin film containing Fe as a main component is used as the main magnetic layer instead of the pure Fe thin film will be described.
That is, except that the main magnetic layer of the soft magnetic thin film shown in FIG. 1 was an Fe ₉₈ Ti ₂ alloy thin film, a soft magnetic laminated film was prepared in the same manner, and its soft magnetic characteristics were measured. The result is shown in FIG. In this figure, the vertical axis represents the film thickness (Å) of the Fe ₉₈ Ti ₂ alloy thin film, and the horizontal axis represents the film thickness (Å) of the Co ₅₀ Zr ₅₀ alloy thin film. From this figure, the combination of each thin film whose saturation magnetic flux density is 20 kG is the case where the film thickness of the Fe ₉₈ Ti ₂ alloy thin film is about 20 times the film thickness of the Co ₅₀ Zr ₅₀ alloy thin film, and the coercive force is as described above. It tends to be slightly lower than any of the soft magnetic laminated films.

The above is the case where the sputtering atmosphere is pure argon. Next, an example in which oxygen or nitrogen is introduced into this atmosphere will be described.

First, 0.4 SCCM oxygen was introduced into the argon atmosphere at the time of sputtering the soft magnetic laminated film shown in FIG. 4 described above, and a soft magnetic laminated film was prepared at a total gas pressure of 2.5 mTorr.
The soft magnetic properties were measured. The result is shown in FIG. In this figure, the vertical axis represents the film thickness (Å) of the Fe ₉₆ Ti ₂ O ₂ thin film, and the horizontal axis represents the film thickness (Å) of the Co ₅₀ Zr ₅₀ alloy thin film.
From this figure, it can be seen that the coercive force is further reduced than the result shown in FIG. 4, and the change in the coercive force with the change in the film thickness tends to be gentle.

Further, an example in which oxygen was replaced with nitrogen in the above experiment was examined. That is, 0.3 S is applied in the argon atmosphere at the time of sputtering the soft magnetic laminated film shown in FIG.
Oxygen of CCM was introduced, the total gas pressure was set to 2.5 mTorr, a soft magnetic laminated film was formed, and the soft magnetic characteristics were measured. The result is shown in FIG. In this figure, the vertical axis represents the film thickness (Å) of the Fe ₉₆ Ti ₂ N ₂ thin film, and the horizontal axis represents the film thickness (Å) of the Co ₅₀ Zr ₅₀ alloy thin film.
Are respectively shown. This figure shows a tendency similar to that of FIG. 5, but the coercive force is further reduced, and the change of the coercive force with respect to the change of the film thickness is further gentle.

Next, a change in coercive force with respect to a change in the thickness of the main magnetic layer when the thickness of the intermediate layer was made constant was examined. In this experiment,
Fe ₈₆ Si ₁₄ alloy thin films of various thicknesses were deposited on the main magnetic layer,
A soft magnetic laminated film (hereinafter, referred to as a FeSi-NiZr-based soft magnetic laminated film) having a 9 層 thick Ni ₅₀ Zr ₅₀ alloy thin film as an intermediate layer, and Fe ₇₀ Ru ₅ Ga _{10 formed in} various film thicknesses A soft magnetic laminated film (hereinafter, referred to as a FeRuGaSi-CoZr-based soft magnetic laminated film) having an intermediate layer of a Si ₁₅ alloy thin film and a Co ₅₀ Zr ₅₀ alloy thin film having a thickness of 13 ° was used. The result is shown in FIG. In this figure, the ordinate indicates the coercive force (Oe), the abscissa indicates the thickness (Å) of the main magnetic layer, the black circle plot indicates the FeSi—NiZr-based soft magnetic laminated film, and the white circle plot indicates the FeRuGaSi—CoZr-based. It corresponds to the characteristics of the soft magnetic laminated film. In any soft magnetic laminated film, the coercive force is improved as the thickness of the main magnetic layer becomes larger than the thickness of the intermediate layer.
The tendency is remarkable in the case of the FeRuGaSi-CoZr-based soft magnetic laminated film.

By the way, the above soft magnetic properties are all measured immediately after the end of sputtering. However, in the manufacturing process of the magnetic head and the like, the stability of the soft magnetic properties after the heat treatment is also increased because the heat treatment for glass fusing or the like is performed. This is one of the important performances required for the soft magnetic laminated film. Therefore, the film thickness 100
Fe Fe ₉₈ Ti ₂ and 10 Co Co ₅₀ Zr ₅₀ are alternately laminated, and a soft magnetic laminated film having a total thickness of 1.2 μm is heat-treated at 500 ° C.
The frequency dependence of the magnetic permeability was investigated. The result is shown in FIG. In this figure, the vertical axis indicates the magnetic permeability, and the horizontal axis indicates the frequency (MHz). From this figure, it can be seen that good flatness is obtained in a frequency region necessary for practical use.

〔The invention's effect〕

As is clear from the above description, the soft magnetic laminated film according to the present invention has a great advantage that the saturation magnetic flux density is extremely high. Further, since an amorphous non-magnetic alloy having a high crystallization temperature is used as the intermediate layer, the characteristics of the laminated film obtained as in the case of using the conventional Co-based amorphous layer are relatively low. Does not deteriorate. Further, since all of the layers to be laminated are made of metal, the problem of delamination between layers as in the case of laminating a metal and an oxide-based nonmagnetic material is avoided.

If a soft magnetic thin film having such soft magnetic properties is mounted on a magnetic head or the like, magnetization of the magnetic head is prevented, and S / N
Good recording / reproducing with a high ratio becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a characteristic diagram showing soft magnetic characteristics of a soft magnetic laminated film having a pure Fe thin film as a main magnetic layer and a Co ₅₀ Zr ₅₀ alloy thin film as an intermediate layer.
The figure is a characteristic diagram obtained by examining the relationship between the combination of film thicknesses and the specific resistance at room temperature for the same soft magnetic laminated film. Figure 3 is pure
FIG. 4 is a characteristic diagram showing soft magnetic characteristics of a soft magnetic laminated film having an Fe thin film as a main magnetic layer and a Ni ₅₀ Zr ₅₀ alloy thin film as an intermediate layer. Fig. 4
FIG. 4 is a characteristic diagram showing soft magnetic characteristics of a soft magnetic laminated film having a Fe ₉₈ Ti ₂ alloy thin film as a main magnetic layer and a Co ₅₀ Zr ₅₀ alloy thin film as an intermediate layer. FIG. 5 is a characteristic diagram showing soft magnetic characteristics of a soft magnetic laminated film having a Fe ₉₆ Ti ₂ O ₂ thin film as a main magnetic layer and a Co ₅₀ Zr ₅₀ alloy thin film as an intermediate layer. FIG. 6 shows that the Fe ₉₆ Ti ₂ N ₂ thin film is composed of a main magnetic layer and Co ₅₀ Z
The r ₅₀ alloy thin film is a characteristic diagram showing the soft magnetic properties of the soft magnetic multilayer film as an intermediate layer. FIG. 7 is a characteristic diagram showing a change in coercive force with respect to a change in thickness of a typical main magnetic layer when the thickness of the intermediate layer is constant. FIG. 8 is a characteristic diagram showing the frequency dependence of the magnetic permeability after heat treatment of a soft magnetic laminated film having a Fe ₉₈ Ti ₂ alloy thin film as a main magnetic layer and a Co ₅₀ Zr ₅₀ alloy thin film as an intermediate layer.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Aso 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-62-93367 (JP, A) JP-A-63-113907 (JP, A) JP-A-63-254709 (JP, A)

Claims (1)

(57) [Claims] 1. A soft magnetic laminated film comprising a main magnetic layer made of pure Fe or a crystalline magnetic alloy thin film containing Fe as a main component, and an intermediate layer made of an amorphous non-magnetic alloy thin film. .