JPS63126208A - Texture-modulated magnetically-soft laminated film - Google Patents

Abstract

PURPOSE:To obtain a texture-modulated magnetically-soft laminated film having both excellent-magnetically-soft property and excellent thermal stability by a method wherein magnetically-soft ferromagnetic thin films and magnetically hard ferromagnetic thin films are laminated, and both thin films is formed almost equal in composition. CONSTITUTION:A magnetically-soft ferromagnetic thin film 2 and a magnetically hard ferromagnetic thin film 3 are alternately laminated. The thin films 2 and 3 are formed almost equal in composition. The crystalline ferromagnetic material having Fe as a main component is used as material of the thin films 2 and 3. The film thickness (l) of the thin film 2 is set within the range of 10-1000Angstrom , and the film thickness (m) of the thin film 3 is set in the range 50-1000Angstrom . As a result, a texture-modulated magnetically-soft laminated film having excellent magnetically-soft characteristics and excellent thermal stability can be obtained.

Description

[Detailed Description of the Invention] [Graduation Field of Application] The present invention relates to a soft magnetic laminated film used as a core material of a magnetic head, etc., and particularly for magnetic fields in alloy composition regions where it is difficult to obtain soft magnetic properties with a single layer film. It improves the characteristics.

[1 Summary of the Invention] The present invention provides a soft magnetic laminated film in which magnetically soft ferromagnetic FjI films and magnetically hard ferromagnetic thin films having substantially the same composition are alternately laminated, and the film structure is periodically stacked. The aim is to obtain a soft magnetic laminated film with high saturation magnetic flux density and excellent thermal stability even in a composition range where it is difficult to obtain soft magnetic properties with a single layer film.

[Conventional technology]

In recent years, in magnetic recording and reproducing devices such as VTRs (video tape recorders), there has been active research into increasing the density and frequency of information signals.

Along with the above-mentioned high-density recording, magnetic recording media include so-called metal tapes that use ferromagnetic metal materials such as Fe, Co, and Ni for magnetic powder, and metal tapes that use ferromagnetic metal materials such as Fe, Co, and Ni on a base film. Is the material directly applied using methods such as vapor deposition? After 1H a
m vapor deposition tapes and the like are being put into practical use.

Since this type of magnetic recording medium has high coercive force,
The core material of the magnetic head used for recording and reproduction is required to have a high saturation magnetic flux density.

That is, since the ferrite material, which has conventionally been frequently used as a core material, has a low saturation magnetic flux density, when the coercive force of the recording medium is increased, the recording characteristics deteriorate.

Conventionally, in order to cope with the above-mentioned high coercive force magnetic recording media, a soft magnetic alloy film having a high saturation magnetic flux density was placed on a non-magnetic substrate such as barium titanate or a magnetic substrate such as ferrite as the core material of the head. A composite magnetic head has been put into practical use in which a magnetic gap is formed by abutting these soft magnetic alloy thin films against each other using a composite magnetic material.

For the soft magnetic alloy 1 film, magnetic alloy materials such as Fe-Aβ-3i alloys (so-called sendust) and amorphous alloys have conventionally been used.

[Problem that the invention seeks to solve]

By the way, in order to achieve higher recording density and improve magnetic properties in magnetic recording, it is necessary to use a soft magnetic alloy thin film having a higher saturation magnetic flux density as the core material, and this development is strongly desired. ing.

Under such circumstances, a method of increasing the content of a transition metal element such as Co in a thin film of a non-crystalline soft magnetic alloy such as the above-mentioned amorphous alloy to increase the saturation magnetic flux density has been considered. However, as the content of transition metal elements increases, there is usually a problem in that the refining temperature decreases.
Highly reliable head processing techniques (glass fusion, etc.) will no longer be applicable.

On the other hand, the above Fe-A/! In the case of crystalline soft magnetic alloy thin films (single-layer films) such as -3i alloys, soft magnetic properties can only be obtained within a limited composition range, and the saturation magnetic flux density is thought to be limited to approximately 10 kilogauss. However, the above requirements cannot be met.

Or a thin film of a different kind from the above-mentioned soft magnetic alloy thin film.

For example, a laminated film in which non-magnetic thin films, oxide magnetic thin films, etc. are alternately laminated has been proposed. However, during the production of the laminated film described above, diffusion phenomena tend to occur at the boundary between the soft magnetic alloy thin film and the thin film of a different type, resulting in deterioration of the soft magnetic properties and leaving unsatisfied results as a core material for a head. ing.

Therefore, in order to realize even higher density recording, it is desired to develop a soft magnetic alloy thin film that has a higher saturation magnetic flux density and also has excellent thermal stability.

Therefore, the present invention has been made to meet the above-mentioned requirements, and has a saturation magnetic flux density that exceeds that of a single layer film, excellent soft magnetic properties, and excellent thermal stability, and is a magnetic material for high-density recording. The object of the present invention is to provide a texture-modulated soft magnetic laminated film suitable for the core material of a head.

[Means for solving problems]

As a result of intensive research to achieve the above-mentioned purpose, the present inventors have found that by changing the conditions for producing ferromagnetic thin films, the resulting ferromagnetic thin films exhibit different magnetic properties. We have found that alternately laminated films exhibit high saturation magnetic flux density.

The texture-modulated soft magnetic laminated film (1) of the present invention was proposed based on the above-mentioned findings, and as shown in FIG. (2) and magnetically hard ferromagnetic thin films (hereinafter referred to as hard thin films) (3) are alternately laminated, and these soft thin films (2) and hard thin films (119 (3)
) is characterized by having approximately the same composition as

The above-mentioned soft thin IJi (2) and hard thin film (3) are made of the same components, and the materials for these thin films (2) and (3) are crystalline ferromagnetic materials whose main component is Fe (
(hereinafter abbreviated as Fe1 alloy) is used. in particular,
Fe Al2-3i alloy, Fe-A1! series alloy, F
c-3i alloy, Fe-Ga-3i alloy, Fe-An
-Ge-based alloys, or some of the Fe in these alloys
Examples include Alloy 2, which is substituted with .

Here, the lI thickness e of the above soft thin IIQ (2) is 10
Hard thin film (3
) is set within the range of 50 to 1000 people. At the same time, the ratio (ρ:m) between the film thickness l of the soft 7iv film (2) and the film yLm of the hard thin film (3) is (20:1
) to (1; 1).

Furthermore, the film 1″7L of the tissue-modulated soft laminated film (1)
is preferably within the range of 0.3 μTn to 30 μm.

Note that the number of layers of the soft gI film (2) and the hard thin film (3) may be any number as long as the above requirements are satisfied.

In order to create a film with approximately the same composition but different properties as described above, it can be easily formed by, for example, changing the sputtering pressure during film formation, or by introducing an impure 1h gas such as nitrogen gas or oxygen gas. .

[Effect]

For example, when a Fe-based alloy such as a Fe-Aff-3i alloy is formed into a film using a method such as a sputtering method, a columnar structure along the crystal growth direction appears. This crystal structure changes depending on the conditions during film formation. In particular, in the sputtering method, determining factors 1 of the film structure during sputtering, such as A
It changes greatly depending on the gas pressure PA, or the introduction of impurity gas such as nitrogen gas or oxygen gas.

In other words, as shown in Fig. 2, when a Fe-A7!-3i alloy thin film is sputtered with the Ar gas pressure PAP set to a low pressure, a fine structure (A) appears, and the Ar gas pressure PAP gradually decreases.
As the Ar is increased, a columnar structure becomes unclear but dense (B) at a few mTorr, and a clear but sparse columnar structure develops under a high gas pressure of several tens of mTorr (C).
appears.

On the other hand, the magnetic properties and crystal structure of these thin films are tangentially related.

For example, an Fe-A6-3i alloy thin film (B
), soft magnetic properties can be obtained by applying appropriate heat treatment.

However, Fe-A6-3i alloy thin film (C) with a sparse columnar structure formed at a high gas pressure P~ of several + mTorr is
Soft magnetic properties are lost.

The present invention improves the soft magnetic properties by dividing the layer (2) exhibiting soft magnetic properties using the magnetically hard layer (3) generated under this high gas pressure PAr as a spacer.

The laminated film (1) formed in this way has improved soft magnetic properties due to the crystal structure of the film, so it is essentially different from a laminated film formed by introducing different elements. At the same time, the deterioration of the magnetic properties due to No. 11 is eliminated, and at the same time, a soft magnetic laminated film with excellent thermal stability is obtained.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Otsu ■↓ First, F eqbs! An alloy consisting of lsA llq (composition: atomic %) was high-frequency melted, and then cast to create a cugette for spackling.

Next, a thin film sample was formed on a crystallized glass substrate by high frequency magnetron sputtering R'l using the above target. Film formation conditions (! Look! With input power constant at 300W, and based on the predetermined deposition rate, Ar gas pressure of 21 II TOrr, 0.1 μm, A, r gas pressure of 20 mT
The spuck time was adjusted so that a film of 0.01 μm was deposited at 0.03 m, and 20 layers of each layer were successively laminated.

Next, the laminated film obtained above was heated at 550°C in vacuum.
When annealing was performed for 1 hour, the main resistance of this laminated film was reduced to 0.4 oersted.

Furthermore, when the A and ■ formations of the laminated film before annealing treatment were analyzed by EPMA, F e 7? , IIS i l+1.
A value of OA n q, + was obtained.

Furthermore, the saturated two-flux density at room temperature of the laminated film before annealing was measured using a vibrating sample magnetometer (VSM) and found to be 12.1 kilogauss.

Further, when the structure of the fractured surface of the Ii3 film after the annealing treatment was observed using a SEM (scanning microscope), a clearly divided columnar structure was observed, although the periodicity was not clear.

, comparison - the same target and sputtering V as in the previous example I
Using FF, a 2 μm thin film sample (single layer film) was continuously formed on a crystallized glass substrate under the condition of Ar gas pressure of 2 mTorr.

The obtained single layer film was annealed in the same manner as in Example 1, and the coercive force was measured to be 1.2 oersted.

In addition, the composition of the single layer film before annealing treatment was the same as in Example 1 (
When measured with Asahi, F Ots, +S i 13.
.

A measurement value of Al, . . . was obtained.

Furthermore, when the )jj and 7J films after annealing treatment were observed using SEM, a continuous columnar structure was observed (second
(crystal structure shown in (B) in the figure).

Comparative Example 2 Using the same target and sputtering apparatus as in Example 1, a 2 μm thick thin film sample (single layer film) was continuously formed on a crystallized glass substrate under an Ar gas pressure of 20 mTorr.

The obtained 111-layer film was annealed in the same manner as in Example 1, and the coercive force was determined to be 4.11, but even when a magnetic field of 100 oersted was applied, it was hardly magnetized and was a magnetically extremely hard layer. It turns out that there is something.

In addition, the composition of the single layer film before annealing treatment was the same as in Example 1 (
F e76,,s i 14 when the floodwaters settled down.
．． 08 β7.3 'IAII constant (direct is 14).

Furthermore, when the single layer film after the annealing treatment was observed using a SEM, a clear columnar (frost columnar) structure penetrating from the substrate surface was observed. [Crystal structure shown as (C) in Figure 2]
.

Example 1 and Comparative Example 1 described above. As is clear from Comparative Example 2, the texture-modulated soft magnetic laminated film having a structure in which soft thin films and hard thin films [9] are alternately laminated by changing the Ar gas pressure during sputtering is such that the columnar structure of the soft thin film is different from that of the hard thin film. It was confirmed that the structure was divided by Furthermore, it was found that the coercive force of the texture-modulated soft magnetic laminated film is extremely smaller than that of this single-layer film, and therefore the saturation magnetic flux density is significantly higher than the limit value (10 kilogauss) for a single-layer film.

〃Soup U Cougets of Fe-Ar-5i alloys having various compositions were prepared, and single-layer films were formed in the same manner as in Comparative Example 1. As a result, the composition range in which soft magnetic properties were obtained was found to be It was confirmed that the content is limited within the range of 74 to 75 at%. In addition, the saturation magnetic flux density of the obtained porcelain film is 10
It was confirmed that it was less than a kilogauss.

Therefore, according to the present invention, it has been found that excellent soft magnetic properties can be obtained even in the alloy composition region where it is difficult to obtain soft magnetic properties with the ji'r fF5 film.

When the method shown in Example 1 was applied to a soft magnetic alloy thin film in which a coercive force of less than 1 oersted could not be obtained with a single layer structure, the results shown in Table 1 were obtained. .

Table 1 As is clear from Table 1, by applying the present invention, a low coercive force that could not be obtained with a single layer can be achieved, and a high saturation magnetic flux density (more than 10 kilogauss) can be easily achieved. It becomes possible to obtain a soft magnetic alloy 'fi film.

〔Effect of the invention〕

As is clear from the above, in the structure-modulated soft magnetic laminated film of the present invention, low coercive force is achieved even in the composition range where it is difficult to obtain soft magnetic properties with a single layer, and high saturation magnetic flux 7. Changes (more than IO=F logauss) can be easily achieved.

In addition, since the (11-weave modulated soft magnetic stacked stone film of the present invention) is essentially different from one in which different magnetic elements or non-magnetic elements are incorporated, the magnetic properties may deteriorate due to diffusion during film formation. do not have.

In addition, since the laminated film of the present invention has a crystalline structure, it has excellent thermal stability, making it possible to apply highly reliable head processing techniques such as glass fusion.

Therefore, the Mi texture modulated soft magnetic product TP! of the present invention! When the J film is used as the core material of a magnetic head, it can be said that the practical value of the present invention is extremely high, since the high coercive force also shows good recording characteristics for serious recording media.

[Brief explanation of the drawing]

FIG. 1 shows M! to which the present invention is applied! FIG. 2 is a schematic cross-sectional view showing a configuration example of a Liff modulated soft magnetic laminated film. FIG. 2 is a schematic diagram showing how the crystal structure of a ferromagnetic thin film changes with changes in argon gas pressure.

Claims (1)

[Scope of Claim] A texture-modulated soft magnetic laminated film comprising a magnetically soft ferromagnetic thin film and a magnetically hard ferromagnetic thin film, the compositions of which are substantially equal.