JP2551008B2 - Soft magnetic thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a soft magnetic thin film, and more particularly to a soft magnetic thin film used as a core or the like of a magnetic head exhibiting performance suitable for high density recording.

[Outline of Invention]

The present invention provides a soft magnetic thin film used as a core of a magnetic head, etc., by adding 0.1 to 5 atomic% Dy to an alloy mainly composed of Fe and / or Co to obtain a high saturation magnetic flux density and a low coercive force. A soft magnetic thin film having:

Further, according to the present invention, by stacking the first soft magnetic thin film layer containing Dy and the second soft magnetic thin film layer having a face-centered cubic structure, it is attempted to achieve further excellent soft magnetic characteristics. It is a thing.

[Conventional technology]

For example, in magnetic recording / reproducing devices such as audio tape recorders and VTRs (video tape recorders), the density and quality of recorded signals are increasing, and so-called metal using ferromagnetic metal powder such as iron as magnetic powder. A tape and a so-called vapor-deposited tape in which a ferromagnetic metal material is directly deposited on a base film by a vacuum thin film forming technique have been put into practical use.

By the way, in order to make good use of the characteristics of the magnetic recording medium having such a high coercive force to perform good recording and reproduction, it is necessary that the core material of the magnetic head has a high saturation magnetic flux density and a low coercive force. is necessary.

Various materials have been developed as soft magnetic materials that meet such requirements, and are used as single-layer films or laminated films.

[Problems to be solved by the invention]

FeCo alloy is one of the materials mentioned above.
Attempts have been made to obtain excellent soft magnetic characteristics by adding various elements such as Si, but there is still much room for research on optimization of various conditions and types of added elements.

Therefore, the present invention aims to improve the soft magnetic properties of FeCo-based alloys, and to provide a soft magnetic thin film having particularly good magnetic properties.

[Means for solving problems]

The soft magnetic thin film according to the present invention has been proposed to achieve the above-mentioned object, and is characterized by mainly containing Fe and / or Co and containing 0.1 to 5 atomic% of Dy. is there.

Further, the soft magnetic thin film according to the present invention is mainly composed of Fe and / or Co and contains Dy in an amount of 0.1 to 5 atomic%.
The soft magnetic thin film layer and the second soft magnetic thin film layer having a face-centered cubic structure are laminated.

Here, the above-mentioned composition range of Dy is set from the viewpoint of soft magnetic characteristics, and good soft magnetic characteristics cannot be expected outside this composition range.

Also, the composition range of Co is 60 atomic% from the viewpoint of soft magnetic characteristics.
Preferably up to.

Furthermore, in order to improve the corrosion resistance and the wear resistance, the soft magnetic thin film may contain Ti, Zr,
At least one of V, Nb, Ta, Cr, Mo, W, B, C, Si, Al, Ge and Ga may be added as the fourth element.

Therefore, the composition of the soft magnetic thin film including the above-mentioned fourth element is Fe _a Co _b Dy _c M _d (where a, b, c, d are composition ratios expressed in atomic%, and M is the The composition range is 0≤b≤60, 0.1≤c≤
5, 0 ≦ d ≦ 5, and a + b + c + d = 100 are satisfied.

In order to form these soft magnetic thin films, sputtering is usually performed, and various methods such as high-frequency magnetron sputtering, direct current sputtering, facing target sputtering, ion beam sputtering, etc. are applicable, and all of them are normal. It can be done under conditions. When adding the above-mentioned fourth element, the alloy of the element to be added and the FeCoDy alloy is used as the target, or the tip of the element to be added is placed on the target made of the FeCoDy alloy and sputtering is performed. I'm fine.

Further, the single-layer film of the soft magnetic thin film mainly has a body-centered cubic structure, but if this is laminated with a magnetic thin film having a face-centered cubic structure such as FeNi alloy or FeCoNi alloy, even better characteristics are obtained. It has been experimentally confirmed that it can be obtained. Here, laminating thin films having different crystal structures is
This is because it is considered to prevent interlayer diffusion and maintain a clear interface even after various manufacturing steps. At this time, the thickness of each thin film and the number of laminated layers may be appropriately selected according to desired magnetic characteristics.

[Action]

In the soft magnetic thin film according to the present invention, 0.1 to 5 atom% of Dy is added to the alloy containing Fe and / or Co as a main component to achieve good magnetic properties even when used as a single-layer film. It becomes possible.

Furthermore, the above-mentioned soft magnetic thin film is used as a first soft magnetic thin film layer,
By stacking this on the second soft magnetic thin film layer, the magnetic characteristics can be further improved.

〔Example〕

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

First, in order to investigate the effect of adding Dy to the FeCo thin film, Fe ₆₀ Co
₄₀ Thin film (numerical values indicate composition in atomic%. The same applies hereinafter), Fe
_{A 60} Co ₃₈ Dy ₂ thin film and, as a comparative example, a thin film (Fe ₆₀ Co ₃₈ Sm ₂ thin film) added with Sm, which belongs to the same lanthanide series as Dy, were formed to have a film thickness of 2 μm, respectively, at the end of sputtering and after the annealing ( The soft magnetic properties at 450 ° C for 1 hour were measured. The results for the Fe ₆₀ Co ₄₀ thin film are shown in FIGS. 1 (A) and 1 (B), and the results for the Fe ₆₀ Co ₃₈ Dy ₂ thin film are shown in FIGS. 2 (A) and 2 (B).
The results for the Fe ₆₀ Co ₃₈ Sm ₂ thin film are shown in FIGS. 3 (A) and 3 (B), respectively. In each of these figures, (A) corresponds to the characteristic at the end of sputtering, and (B) corresponds to the characteristic at the end of annealing.

First, regarding the Fe ₆₀ Co ₄₀ thin film, as can be seen from FIG. 1A, the saturation magnetic flux density is sufficiently high but the coercive force is large at the end of sputtering. After annealing this thin film, as can be seen from FIG. 1 (B), the coercive force decreases, but the saturation magnetic flux density decreases, and the magnetic permeability also decreases. Is a disadvantage.

Next, of the components of the above-mentioned Fe ₆₀ Co ₄₀ thin film,
Looking at the Fe ₆₀ Co ₃₈ Dy ₂ thin film in which Co is replaced by Dy, as can be seen from FIG. 2 (A), the saturation magnetic flux density and magnetic permeability at the end of sputtering are almost the same as those of the Fe ₆₀ Co ₄₀ thin film described above. It was found that the coercive force was effectively reduced while maintaining it. Even after annealing this thin film, as can be seen from FIG. 2 (B), the coercive force was further improved while maintaining the saturation magnetic flux density at a high value.

As a comparative example, looking at a Fe ₆₀ Co ₃₈ Sm ₂ thin film in which Sm is added in an amount of 2 atom% instead of Dy, as can be seen from FIGS. 3 (A) and 3 (B), annealing is completed at the end of sputtering. It was found that the soft magnetic properties did not appear at any of the terminations, and it could not be used as a magnetic material.

As described above, the effect of adding Dy in the single-layer film made of the FeCo alloy was clarified. Next, the FeCoDy thin film was used as the first soft magnetic thin film layer, and this was laminated with the second soft magnetic thin film layer. Was considered.

First, the first soft magnetic thin film layer having the composition of Fe ₆₀ Co ₃₈ Dy _{2 and} the composition of Fe ₁₉ Ni ₈₁ are used as in the example shown in FIGS. 2 (A) and 2 (B). The coercive force at the end of sputtering was measured for a laminated film in which the second soft magnetic thin film layer was laminated with various thicknesses. The results are shown in FIG. The sputtering conditions are gas pressure.
4 mTorr, total thickness of laminated film is 3.6 μm.

In this figure, the vertical axis represents the film thickness (Å) of the Fe ₆₀ Co ₃₈ Dy ₂ thin film, and the horizontal axis represents the film thickness (Å) of the Fe ₁₉ Ni ₈₁ thin film. In the L-shaped region surrounded by the dotted line and these two axes, the film thickness of one thin film is sufficiently larger than the film thickness of the other thin film. It means that the alloy phase is not achieved and almost becomes an alloy phase. Each point in the figure shows a combination of the measured film thickness of each laminated film, and a solid line connecting these in a substantially arc shape is an Hc line connecting points having the same coercive force (Hc). The alternate long and short dash line is an iso-Bs line connecting points with the same saturation magnetic flux density (Bs).

From this figure, it can be seen that Fe ₁₉ Ni is generally compared to Fe ₆₀ Co ₃₈ Dy ₂ thin film.
_It was confirmed that the _81- thick laminated film tended to have lower coercive force.

Next, with respect to the above-mentioned Fe ₆₀ Co ₃₈ Dy ₂ thin film, with respect to Fe ₅₈ Co ₄₀ Dy _{2 in} which the composition of Fe and Co was slightly changed, a laminated film with the Fe ₁₉ Ni ₈₁ thin film was similarly changed while variously changing the film thickness. It was created and the coercive force at the end of sputtering was measured. This result is the fifth
Shown in the figure. The sputtering conditions are gas pressure 2.5 mTo
rr, the total thickness of the laminated film is 1.8 μm.

In this figure, the vertical axis represents the film thickness (Å) of the Fe ₅₈ Co ₄₀ Dy ₂ thin film, and the horizontal axis represents the film thickness (Å) of the Fe ₁₉ Ni ₈₁ thin film. The entries are the same as those in FIG. 4 described above.

From this figure, it was confirmed that the coercive force is low when the two thin films have almost the same film thickness, and the coercive force tends to increase as the film thickness of the Fe ₅₈ Co ₄₀ Dy ₂ thin film increases.

The example of stacking the FeCoDy-based thin film with the FeNi-based thin film has been described above with reference to FIGS. 4 and 5. Next, an example of stacking the FeCoNi-based thin film as the second soft magnetic thin-film layer in place of the FeNi-based thin film investigated. That is, Fe ₅₈ Co shown in FIG.
_{The 40} Dy ₂ thin film and the Fe ₃₀ Co ₃₅ Ni ₃₅ thin film were laminated by changing the combination of film thicknesses, and the coercive force was measured after sputtering. The results are shown in FIG. The gas pressure during sputtering is 2.5 mTorr, and the total thickness of the laminated film is 1.8 μm.

In this figure, the vertical axis represents the film thickness (Å) of the Fe ₅₈ Co ₄₀ Dy ₂ thin film, and the horizontal axis represents the film thickness (Å) of the Fe ₃₀ Co ₃₅ Ni ₃₅ thin film. The value of the coercive force is written above the point indicating the combination of each film thickness. From this figure, the systematic relationship between the film thickness and the coercive force is not clear as in FIGS. 4 and 5 above, but in general, compared with the Fe ₅₈ Co ₄₀ Dy ₂ thin film, Fe ₃₀ Co ₂₅ Ni
It was found that soft magnetic thin films with a large thickness of ₄₅ thin films tend to have low coercive force.

〔The invention's effect〕

As is clear from the above description, the soft magnetic thin film according to the present invention has a sufficiently low coercive force at the end of sputtering, and even when it is used as a single-layer film in a magnetic head or the like, heat treatment such as glass fusion The soft magnetic properties are not impaired in the process.

Further, when the soft magnetic thin film is used as a first soft magnetic thin film layer and is used as a laminated film in which the soft magnetic thin film is laminated with the second soft magnetic thin film layer, the soft magnetic characteristics are further improved.

When a soft magnetic thin film having such soft magnetic properties is applied to a magnetic head, magnetization of the magnetic head is prevented, distortion is small, and good recording / reproduction with a high S / N ratio becomes possible.

[Brief description of drawings]

FIGS. 1 (A) and 1 (B) are characteristic diagrams showing hysteresis curves of Fe ₆₀ Co ₄₀ thin films. FIG. 1 (A) is at the end of sputtering, and FIG. 1 (B) is at the end of annealing. It represents the characteristics of each. 2 (A) and 2
FIG. 2B is a characteristic diagram showing the hysteresis curve of the Fe ₆₀ Co ₃₈ Dy ₂ thin film, and FIG.
FIG. 2B shows the characteristics at the end of annealing. 3A and 3B show Fe ₆₀ Co _38.
FIG. 3 is a characteristic diagram showing a hysteresis curve of an Sm ₂ thin film,
FIG. 3A shows the characteristics at the end of sputtering, and FIG. 3B shows the characteristics at the end of annealing. Figure 4
Fe ₆₀ Co ₃₈ Dy ₂ thin film and Fe ₁₉ Ni ₈₁ characteristic diagram showing the film thickness dependency of the coercive force of the laminated film of the thin film, Fig. 5 Fe ₅₈ Co ₄₀ Dy ₂ thin film and the F
e ₁₉ Ni ₈₁ Characteristic diagram showing film thickness dependence of coercive force of laminated film with thin film, Fig. 6 is film of coercive force of laminated film of Fe ₅₈ Co ₄₀ Dy ₂ thin film and Fe ₃₀ Co ₃₅ Ni ₃₅ thin film It is a characteristic view which shows thickness dependence.

Claims (2)

(57) [Claims] 1. Fe and / or Co as a main component and Dy of 0.1 to
A soft magnetic thin film containing 5 atom%. 2. Fe and / or Co as a main component and Dy of 0.1 to
A soft magnetic thin film comprising: a first soft magnetic thin film layer containing 5 atomic% and a second soft magnetic thin film layer having a face-centered cubic structure.