JPH02174205A - Soft magnetic thin film - Google Patents

Abstract

PURPOSE:To reduce coercive force Hc and improve corrosion-resistance by incorporating 12-25atom% Si, 0.5-10atom% Ru, and remaining Fe as chief ingredients into a material of the title thin film. CONSTITUTION:A soft magnetic thin film is formed on a crystallized glass substrate by RF sputtering by properly disposing two kinds of small pieces of Si and Ru on a pure Fe (3N) target. The soft magnetic thin film incorporates therein as chief ingredients 12-25atom% Si, 0.5-10atom% Ru, and remaining Fe. By the existence of the 0.5-10atom% Ru, coercive force Hc can be reduced and corrosion resistance can be improved. Ru preferably ranges from 1 to 8atom% and more preferably from 2 to 6atom%. Si preferably ranges from 17 to 23atom% when Si is less than 12atom%, for example when Si is 11atom%, the coercive force Hc is increased by addition of Ru, and not preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a soft magnetic thin film suitable as a material for a magnetic head.

[Background of the Invention] For example, in magnetic recording and reproducing devices such as audio tape recorders and VTRs (video tape recorders), the density and quality of recording signals are increasing, and it is necessary to cope with this increase in recording density. Fe is added to magnetic powder as a magnetic recording medium.
, Co, N1, or other metals or alloys were used. A so-called metal tape or a ferromagnetic metal material was deposited directly onto the base film by vacuum thin film formation technology. So-called vapor deposition tapes have been developed and put into practical use in eight different fields.

[Issue 8 to be solved by the prior art and the invention] By the way, in order to exhibit the characteristics of a magnetic recording medium having such a high coercive force, a high saturation magnetic flux density is required as a characteristic of the core material of the magnetic head. If the same magnetic head is to be used for reproduction, it is also required to have high magnetic permeability. For example, ferrite materials, which are commonly used as core materials for conventional magnetic heads, have a low saturation magnetic flux density, and permalloy has problems with wear resistance.

Conventionally, it has been used as a core material that satisfies these various requirements.

Sendust alloys made of Fe-A and g-8t alloys are considered suitable and have already been put to practical use.

However, in materials with excellent soft magnetic properties such as this Sendust alloy, magnetostriction λS and magnetocrystalline anisotropy K
It is desirable that both of these values be around zero, and the material composition that can be used in the magnetic head is determined by taking these two values into consideration. Therefore, the saturation magnetic flux density is also uniquely determined according to this composition.

In the case of Sendust alloy, the limit is 10 to 11 Gauss.

Therefore, instead of the Sendust alloy mentioned above, an amorphous magnetic alloy material (so-called amorphous magnetic alloy material) that has a high saturation magnetic flux density with little decrease in magnetic permeability in the high frequency region has been developed. Even with alloy materials, the saturation magnetic flux density is about 12 Gauss, and since they are thermally unstable and have a high possibility of crystallization, it is not possible to apply temperatures over 500°C for a long time. There are process limitations when using it for magnetic heads that require various heat treatments.

An object of the present invention is to provide a soft magnetic thin film that improves the drawbacks of the above-mentioned conventional techniques.

[Means for Solving the Problems] According to the present invention, 12 to 25 atomic % (at%) of Si
The above object can be achieved by a soft magnetic thin film mainly composed of 0.5 to 10 atomic % Ru and the balance Fe.

[Preferred embodiments and effects] The soft magnetic thin film of the present invention contains 12 to 25 atomic % of Si and 0
．． The main components are 5 to 10 atomic % of Ru and the balance is Fe. Due to the presence of 0.5 to IO atomic % Ru, the coercive force 1
1c can be lowered, and corrosion resistance can be improved. The preferred range of Ru is 1 to 8 at%, more preferably 2 to 6 at%. Ru is 0.5
If it is less than atomic %, it is often difficult to achieve the effects of the presence of Ru, that is, to reduce the coercive force lie and improve corrosion resistance.On the other hand, if it exceeds 10 atomic %, the coercive force He will increase, which is undesirable. .

When the Sl content is 12 atomic % or more, the coercive force He can be reduced by adding Ru. but.

When Sl exceeds 25 at%, the saturation magnetic flux density Bs decreases to less than 12 KG, and Fe-Al-5t system and Fe-
The specific advantage over Ga-5t-Ru soft magnetic material is lost. The preferred range of Si is 17 to 23 atomic %. When Si is less than 12 atomic % 1 For example, Si is 11
In the case of atomic %, the addition of Ru increases the coercive force He, which is not preferable.

The soft magnetic thin film of the present invention can be manufactured by forming the film by a vapor phase deposition method such as RF sputtering, and then heat-treating the film at about 350 to 600°C. The heat treatment may be carried out in two ways, for example,
About 1 hour is sufficient.

If the heat treatment is performed at a temperature of about 300°C or less, H
It is not preferable to manufacture products with e exceeding a predetermined range, and conversely, if the temperature is 2, for example, 800° C. or higher, the characteristics may deteriorate due to reactions with the substrate, etc. The preferred temperature range is approximately 350 to 550°C.

[Example] A crystallized glass substrate (manufactured by Hoya Glass Co., Ltd., trade name: HOYA PEG31) was prepared by RF sputtering by appropriately disposing 2N pieces of St and Ru on a pure Fe (3N) target.
30C), thin films of various components were formed on the top. The sputtering conditions are cathode power 200W, Ar gas pressure 2.0P.
It was a. The thin film was heat-treated at 500° C. for 1 hour to obtain a soft magnetic thin film, and the B-H curve n1 was determined. B-H
The curve was measured by applying a magnetic field of 25 (Oe) at a frequency of 50 Hz, and the coercive force 11c was determined. Also, the saturation magnetic flux density B
s was measured. FIGS. 1 and 2 are plots of the results classified by Si content. According to Figure 1, Hc increases with the addition of Ru in the case of 5il1%, but the Hc increases in the case of 13% or more of Sl.
It can be seen that the addition of u further reduces He, and it can be seen from FIG. 2 that the soft magnetic thin film of the present invention has a large saturation magnetic flux density Bs.

[Effect of the invention] The soft magnetic thin film of the present invention has 12 to 25 at% of St and 0
．． It is mainly composed of 5 to 10 atomic % Ru and the balance Fe, and the presence of Ru can reduce the coercive force He and improve corrosion resistance. Saturation magnetic flux density 111s (12K
G).

Therefore, by using this soft magnetic thin film as a core material of a magnetic head, for example, it is possible to sufficiently cope with the increase in coercive force of a magnetic recording medium, and it becomes possible to achieve higher quality and higher recording density.

[Brief explanation of the drawing]

Fig. 1 shows the coercive force He of the soft magnetic thin film mainly composed of Si Ru (at%), and Fig. 2 shows the saturation magnetic flux density Bs of the soft magnetic thin film Hc ( Oe) This is a diagram shown in the figure.

Claims (1)

[Claims] A soft magnetic thin film mainly composed of 12 to 25 atomic % Si, 0.5 to 10 atomic % Ru, and the balance Fe.