JPH0744109B2 - Soft magnetic thin film - Google Patents

Description

The present invention relates to a soft magnetic thin film suitable for use in, for example, a thin film magnetic head.

[Outline of Invention]

The present invention is a soft magnetic thin film of a nitrogen-containing Co-Si-Fe-based composition, and the coercive force Hc is small by specifying the composition, and the magnetic permeability μ
It is intended to obtain a soft magnetic thin film having high corrosion resistance and high corrosion resistance.

[Conventional technology]

In various magnetic recording / reproducing devices, there is an increasing demand for higher density recording and higher frequency, and correspondingly, magnetic recording media having high saturation magnetization and high coercive force are used. As this kind of magnetic recording medium, a so-called metal tape using a powder of a ferromagnetic metal such as Fe, Co, or Ni, a so-called vapor deposition tape formed by coating a ferromagnetic metal material on a base film, and the like are used. Has reached.

Accordingly, a magnetic head for this type of magnetic recording medium is required to be made of a head material having a high saturation magnetic flux density and a high magnetic permeability, and has a small magnetic anisotropy and zero magnetostriction, and a coercive force. Is required, and the head material is required to have not only magnetic characteristics but also chemical stability and excellent mechanical characteristics such as high wear resistance and excellent corrosion resistance as a head material.

On the other hand, along with the high density recording, it is required to reduce the recording track width, and hence the track width of the working magnetic gap in the magnetic head, and to meet this requirement, particularly, the mass productivity is remarkably improved in the multi-track magnetic head. As a measure that can be measured, a thin film magnetic head using a thin film technique for forming a magnetic head core of a soft magnetic thin film on a non-magnetic or magnetic substrate is remarkably popularized. As a soft magnetic thin film of this kind, a sendust alloy thin film containing Fe, Al and Si as main components has been attracting attention.

Since this sendust alloy thin film has a high saturation magnetic flux density Bs and a relatively high hardness, it can be applied to a magnetic recording medium having a high residual magnetic flux density such as the metal tape described above. is there.

However, although this sendust alloy thin film has a relatively high hardness, it is inferior in wear resistance and corrosion resistance to, for example, a ferrite material. Further, since this Sendust alloy thin film has a relatively low specific resistance, when it is used as a core of a magnetic head, a decrease in magnetic permeability in a high frequency region due to so-called eddy current loss is a problem, and high frequency There is a problem that sufficient reproduction output may not be obtained in the area.

On the other hand, it is considered to use an amorphous magnetic alloy material having a high saturation magnetic flux density Bs with a small decrease in permeability in the high frequency region instead of the sendust alloy thin film. Amorphous magnetic alloy materials have a difficulty in heat resistance, and their magnetic permeability is greatly deteriorated by long-time heating and thermal cycles, resulting in poor reproduction efficiency. In particular, since there is a high possibility of crystallization, it is not possible to apply a temperature of 500 ° C or higher for a long time, and for this reason, in the manufacturing process of the magnetic head, for example, glass fusion treatment at a temperature of 500 ° C or higher is required. There is a problem that it is not preferable to take the necessary steps.

Under such circumstances, research on soft magnetic materials exhibiting even better soft magnetic properties has been promoted. For example, in Tatsuharu Yamamoto and Kuki Chiba, “Journal of the Japan Institute of Metals”, Volume 14, B, No. 2 (1950). Have reported that an Fe-Co-Si based alloy material containing Fe, Co, and Si as main components exhibits excellent soft magnetic properties.

However, this Fe-Co-Si alloy material is extremely fragile and poor in practicality, and there is a problem in using it as it is as a core material of a magnetic head.

[Problems to be solved by the invention]

The present invention has improved the above-mentioned various problems, and has magnetic characteristics, that is, a large saturation magnetic flux density Bs, a small coercive force Hc, a magnetostriction λs of almost zero, a small magnetic anisotropy, and a mechanical characteristic, that is, high. It is intended to provide a soft magnetic thin film having hardness, excellent wear resistance, thermal stability and high heat resistance, and chemical stability, that is, excellent corrosion resistance.

[Means for solving problems]

The present invention is based on the finding that the above-mentioned problems can be improved by adding nitrogen N to a magnetic thin film containing Fe, Co, and Si as main components without lowering the saturation magnetic flux density. is there.

That is, in the present invention, Fe, Co, and Si are the main components, and the composition is 5 to 15 atom% of Co, 17 to 23 atom% of Si, and 0.01 to N of N.
5 atomic% and balance Fe.

The thickness of the soft magnetic thin film of the present invention having the above composition is preferably 10 Å or more and 1 mm or less, and more preferably 10 Å or more and 100 μm or less.

[Action]

As described above, the soft magnetic thin film according to the present invention is mainly composed of Fe, Co and Si, but is characterized in that it contains nitrogen N, which significantly improves the magnetic permeability and hardness. The specific resistance is improved.

In the soft magnetic thin film according to the present invention, high temperature (for example, 550
When heat-treated at (° C.), It is crystallized and soft magnetic properties are obtained. Therefore, it does not have the thermally unstable property of the amorphous magnetic thin film.

According to the experiments conducted by the present inventors, the magnetic permeability rapidly increases as the content of nitrogen N in the magnetic thin film increases. For example, when the content of nitrogen N is about 1.6 atomic%, nitrogen N is completely eliminated. It was found that the magnetic permeability reached about 1.5 times that of the magnetic thin film that did not contain it. Further, this magnetic permeability rather decreases when the content of nitrogen N contained in the magnetic thin film becomes too large. However, since the specific resistance of this magnetic thin film increases with an increase in the nitrogen N content, the N content is 5 when considering its use in a higher frequency region, for example, in a magnetic head for a digital VTR. Practical use is possible up to about atomic%.

In addition, as the content of N contained in the magnetic thin film increases,
The Vickers hardness also rapidly increased, and it was found that a substantially constant hardness can be secured when the N content exceeds about 2 atomic%.

That is, when the content of nitrogen N contained in the magnetic thin film according to the present invention is less than 0.01 atomic%, no sufficient effect can be expected, and when the content exceeds 5 atomic%, Since the magnetic permeability may decrease and the coercive force Hc may increase, 0.01 to 5 atom% is selected.

In the soft magnetic thin film according to the present invention, the Si content is
Even if it is less than 17 atomic%, or conversely exceeds 23 atomic%, the coercive force Hc of the obtained soft magnetic thin film becomes large, and it cannot be used as the core material of the magnetic head. Even if the Co content is less than 5 at%, vice versa
The coercive force Hc increases even if it exceeds atomic%.
This results in a low coercive force Hc by setting the composition range of Si to 17 to 23 atomic% and Co to 5 to 15 atomic%, but the magnetostriction could be made closer to zero in this region.

Further, when the Si content is too high, the saturation magnetic flux density is lowered. From this point as well, it is preferable to suppress the Si content to about 23 atomic%.

[Example] As a method of manufacturing a soft magnetic thin film according to the present invention, a so-called vapor phase thin film forming technique is preferable. This is because, for example, it is difficult to uniformly introduce a large amount of nitrogen by a general melting method. That is, nitrogen is usually floated as slag during alloy melting and separated from the alloy as impurities.

Therefore, the soft magnetic thin film according to the present invention is preferably manufactured by a vapor deposition method, an ion implantation method, or the like.
Examples of the vapor deposition method include flash vapor deposition, vapor deposition in gas, ion plating, sputtering, cluster ion beam method, and the like, and vapor deposition and ion implantation may be performed simultaneously. As a method of introducing nitrogen N into the magnetic thin film, (1) vapor deposition or the like is performed in an atmosphere containing nitrogen gas, and the content of nitrogen N in the obtained magnetic thin film is adjusted by the concentration of this nitrogen gas. How to introduce.

(2) A method of using a compound of nitrogen N and at least one element of each component, and an alloy of the remaining components as an evaporation source, and introducing nitrogen N into the obtained magnetic thin film, and the like. To be In addition, Fe, Co, Si that compose the magnetic thin film
As a method of adjusting the composition of each component element such as (1) Fe, Co, Si and other additives, substitution metals, etc. are weighed so as to have a predetermined ratio, and these are preliminarily used, for example, in a high frequency melting furnace, etc. A method of using the alloy ingot as an evaporation source by melting the alloy ingot to form an alloy ingot, (2) preparing an evaporation source for each element of each element, and controlling the composition by the number of these evaporation sources, (3) A method of preparing evaporation sources for individual elements of each component and controlling the output (applied voltage) applied to these evaporation sources to control the evaporation speed, and (4) while vapor-depositing an alloy as an evaporation source. A method of implanting another element, and the like are included.

Example 1 Electrolytic iron, electrolytic cobalt, and metallic silicon were used as raw materials, and each of these raw materials was weighed and separated, and then melted in a vacuum using a high-frequency melting furnace, poured into a mold, and molded to have a diameter of 50 mm, An electrode target having a thickness of 1 mm was produced.

Using the above target, sputtering was performed by a magnetron type sputtering device under the following sputtering conditions.

Sputtering conditions RF power 250W Target-substrate distance 35mm Substrate temperature -20 ° C (water cooling) Ultimate vacuum 3 × 10 ^-6 Torr Gas pressure 8 × 10 ^-3 Torr Film thickness 2.8-3.1 μm Inert according to the above sputtering conditions Ar gas was used as a gas, and N ₂ was mixed in this Ar gas for sputtering. Here, the amount of N ₂ mixed was controlled by partial pressure, and sputtering was performed while changing the ratio of N ₂ to form a Fe—Co—Si alloy thin film on the crystallized glass substrate. Obtained Fe-Co
The —Si alloy thin film was heat-treated at 550 ° C. for 1 hour.

In Example 1, the film composition obtained when the partial pressure of the N ₂ gas was changed, the coercive force Hc and the magnetic permeability μ at 5 MHz
_The results of measuring corrosion resistance at _5MHz are shown in the drawing. Incidentally, the measurement of each composition was carried out by the Innertogas diffusion (thermal conductivity) method for N, and EPMA (Electric Probe Micro Anals) for the other.
is). The corrosion resistance was measured by immersing the measurement sample in a 1N NaCl solution for 9 hours and visually observing the rusting state of the surface. The ◎ mark indicates that the mirror surface was kept, and the ◯ mark indicates The surface is fogged, and the mark Δ indicates that thin rust is partially generated.

For comparison, the measurement results are also shown for those containing no N in the table of the same drawing.

As is clear from these measurement results, the N-containing soft magnetic thin film according to the present invention can improve the magnetic permeability and the corrosion resistance without significantly increasing the coercive force Hc as compared with the N-free soft magnetic thin film. I'm sick.

As described above, since the soft magnetic thin film according to the present invention contains nitrogen N as a component thereof,
Although high permeability and corrosion resistance can be achieved, even higher hardness can be achieved and wear resistance can be improved. At this time, deterioration of magnetic properties such as saturation magnetic flux density and coercive force. Can not be seen. In particular, the inclusion of nitrogen N increases the specific resistance and reduces the eddy current loss in the high frequency region.
This is extremely useful for magnetic heads and the like used in the above high frequency range.

Although the details of the role played by nitrogen N in this magnetic thin film are unknown, it is expected that nitridation of Fe and generation of high hardness particles such as silicon nitride will occur because the hardness is remarkably improved.

Further, in the above-mentioned soft magnetic thin film according to the present invention, various elements may be added as an additive in order to further improve various properties such as corrosion resistance and abrasion resistance. The elements used as this additive include Group IVa elements such as Ti, Zr, and Hf, and V and N.
Va group elements such as b and Ta, VI a group elements such as Cr, Mo and W, VI such as Mn
Ia group elements, and further platinum group elements include platinum group elements of the 5th period, that is, Ru, Rh, Rd, platinum group elements of the 6th period, that is, Os, Ir, Pt, etc. One kind or two or more kinds of additives may be combined and added in an amount of 0 to 10% by weight based on the magnetic thin film.

Further, in some cases, oxygen can be contained together with nitrogen N.

〔The invention's effect〕

As described above, according to the soft magnetic thin film of the present invention, the saturation magnetic flux density is reduced and without increasing the coercive force, it has a high magnetic permeability, excellent corrosion resistance, and excellent wear resistance of high hardness,
Furthermore, since it is possible to obtain a soft magnetic thin film having excellent heat resistance without thermal instability as in an amorphous magnetic thin film, it can be used as a thin film magnetic core of a thin film magnetic head for high density recording, and its profit is extremely high. Is large.

[Brief description of drawings]

The figure is a table showing the composition of the soft magnetic thin film and the measurement results of each characteristic.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitaka Ochiai 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Hideki Matsuda 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Hiroshi Iwasaki 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Koichi Aso 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni -Incorporated (56) References JP 54-94428 (JP, A) JP 58-27941 (JP, A)

Claims (1)

[Claims] 1. Co of 5 to 15 atomic%, Si of 17 to 23 atomic%, N
Of 0.01 to 5 atomic% and the balance being Fe.