JPH0744106B2 - 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.

[Summary of the Invention] The present invention is a soft magnetic thin film of a Fe-Al-Ge system containing nitrogen, which has a low coercive force Hc and a high magnetic permeability μ due to the composition of the soft magnetic thin film, and particularly has excellent corrosion resistance and hardness A thin film is obtained.

[Conventional technology]

2. Description of the Related Art In various magnetic recording / reproducing devices, demands for high density recording and high frequency ratio are increasing, 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-term 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 by adding nitrogen N to a magnetic thin film containing Fe, Al and Ge as main components, the above-mentioned problems can be improved without lowering the saturation magnetic flux density. is there.

That is, the present invention is represented by a composition ratio of Fea Alb Gec Nx (provided that a, b, c and x are each represented by atomic%), and each composition range is 55a84 1b31 1c31 0.1x30. And a soft magnetic thin film having a composition of a + b + c + x = 100.

In the above composition, part of Al is Ga and part of Ge is Si.
Can be replaced with. Also, part of Fe is at least 1 of Co or Ru.
It can be replaced by up to 15 atom% of seed.

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

[Action]

The soft magnetic thin film according to the present invention has a higher saturation magnetic flux density than the Sendust alloy, and by containing N, the magnetic permeability is higher and the specific resistance is higher than that of the Fe-Al-Ge based alloy containing no N. Was improved, and the hardness and thus the wear resistance were 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.

In the soft magnetic thin film according to the present invention, with respect to the composition ratio of each element of Fe, Al and Ge, that is, the values of a, b and c, outside the above range, the magnetostriction becomes large and the magnetic characteristics are deteriorated. With respect to the composition ratio of x, that is, the value of x, if this is outside the above range, that is, if x is less than 0.1 atom%, no effect due to addition of N such as specific resistance and hardness is observed, and if x exceeds 30 atom%. On the contrary, the magnetic permeability is lowered, and the coercive force Hc is increased, which causes inconvenience.

Further, in the above composition, when substituting a part of Fe with Co, it is possible to further improve the saturation magnetic flux density Bs and the corrosion resistance, and when substituting a part of Fe with Ru, Ru Despite being a non-magnetic element, it was possible to further improve the corrosion resistance and the wear resistance without impairing the soft magnetic characteristics and hardly causing a decrease in Bs.

〔Example〕

The method for producing the soft magnetic thin film according to the present invention is preferably based on a so-called vapor phase thin film forming technique. 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 produced 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. Further, 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 magnetic thin film obtained by adjusting the concentration of the nitrogen gas is adjusted. 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. To be In addition, Fe, Al, Ge that make up the magnetic thin film
As a method of adjusting the composition of each component element such as (1) Fe, Al, Ge 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. Melt to form an alloy ingot,
A method of using this alloy ingot as an evaporation source, (2) a method of preparing evaporation sources of individual elements of each component and controlling the composition by the number of these evaporation sources, (3) an evaporation source of individual elements of each component Prepared and controlling the output (applied voltage) applied to these evaporation sources to control the evaporation speed to control the composition, (4) a method of implanting another element while depositing an alloy as an evaporation source, and the like. .

Example 1 Metals of iron, aluminum, and germanium were weighed, melted in a vacuum using a high-frequency melting furnace, poured into a mold, and molded to prepare a sputtering target having a diameter of 105 mm and a thickness of 4 mm.

Using this target, sputtering was performed using a planar magnetron type sputtering device under the following sputtering conditions.

Sputtering conditions RF power 300W Target-substrate distance 55mm Substrate temperature Water cooling Ultimate vacuum 3 × 10 ^-6 Torr Gas pressure 5 × 10 ^-3 Torr Film thickness 2.8-3.1 μm Ar gas is used as an inert gas according to the above sputtering conditions. This Ar gas was mixed with N ₂ and sputtering was performed. 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 an Fe-Al-Ge based alloy thin film containing N on the crystallized glass substrate. The obtained Fe-Al-Ge alloy thin film containing N 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 1 MHz
_The results of measuring the corrosion resistance at _1MHz are shown in the drawing. Here, the corrosion resistance is 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 a mirror surface even after being immersed in the above-mentioned NaCl for 48 hours. ◯ mark was clouded on the surface under the same conditions and was a mirror surface after 48 hours in city water, △ mark was clouded on the film surface after immersion in city water for 48 hours, × The mark indicates that a thin red rust occurred on the film surface after immersion in city water for 48 hours.

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

The measurement of each composition was carried out by the Innertogas diffusion (thermal conductivity) method for N, and EPMA (Electric Probe Micro Ana) for the other.
lsis).

As is clear from these measurement results, the N
The contained soft magnetic thin film is improved in magnetic permeability and corrosion resistance without increasing the coercive force Hc as compared with the soft magnetic thin film not containing N.

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 is also observed. I can't. Particularly, by containing nitrogen N, the specific resistance increases, and the eddy current loss in the high frequency region decreases, so that the frequency characteristic of the magnetic permeability is improved and the magnetic head used in the high frequency region of 10 MHz or more, etc. Will be extremely useful for

Although the details of the role played by nitrogen N in this magnetic thin film are unknown, it is expected that high hardness particles such as Fe nitrides will be generated since 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. As the element used as this additive, Ti, Zr, IVa group elements such as Hf, V, Nb,
Va group element such as Ta, VIa group element such as Cr, Mo, W, VIIa group element such as Mn, and platinum group element of the fifth period as a platinum group element,
That is, Rh, Rd, platinum group element of the 6th period, that is, Os, I
r, Pt, etc. may be mentioned, and one or more of these additives may be combined and added in the range of 0 to 10 atomic% with respect to 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) Reference JP-A-58-27941 (JP, A)

Claims (1)

[Claims] 1. Fea Alb Gec Nx (where a, b, c and x are
The soft magnetic thin film is characterized in that each composition range is 55a84 1b31 1c31 0.1x30, and a + b + c + x = 100.