JPH0242702A - Soft magnetic thin film and magnetic head using such thin film - Google Patents

Abstract

PURPOSE:To obtain a soft magnetic thin film having high saturation magnetic flux density and having both high durability and high permeability by laminating layers of iron carbide and iron alternately. CONSTITUTION:Layers of iron 12 and layers of iron carbide 11 having a concentration of C in a range corresponding to positive magnetostrictive constants are laminated alternately. According to such an arrangement, even if carbon is incorporated in the iron carbide layers 11 in an amount enough to present sufficient durability at the sacrifice of saturation magnetic flux thereof, the presence of the pure iron layers 12 ensures sufficient saturation magnetic flux and instability of the pure iron layers 12 can be compensated by the adjacent iron carbide layers 11. Further, the negative magnetostriction of the pure iron layers 12 and the positive magnetostriction of the iron carbide layers 11 are cancelled each other, whereby the soft magnetic thin film thus obtained is allowed to have sufficiently high permeability also. Accordingly to the invention, consequently, the soft magnetic thin film having high saturation magnetic flux density is allowed to have both high durability and high permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides excellent recording and reproducing properties for soft magnetic thin films used in magnetic heads, magnetoresistive elements, etc., particularly for high-coercivity, high-density magnetic recording media. The present invention relates to a soft magnetic thin film having a soft magnetic thin film and a magnetic head using the same.

Prior Art Ferrite, a metal oxide, has been widely used as a material for conventional magnetic heads. In recent years, permalloy with higher saturation magnetic flux density, Kkeru iron-based alloy) and Sendust (
Iron-aluminum-silicon alloys) are also used.

More recently, an amorphous material (cobalt-zirconium amorphous alloy) with a saturation magnetic flux density of 1.0 to 1.4 Tesla has been developed and is beginning to be used for heads compatible with metal tapes such as 8 mm VTRs.

In response to demands for increased recording density, magnetic materials with high saturation magnetic flux density have appeared one after another, but advances in media have also been remarkable, and with the advent of metal tapes, the coercive strength of conventional oxide tapes has increased from 600 to 600. 150 for 7005e
Media with coercivity of 0 to 20''000 e can now be obtained.

Next-generation high-capacity magnetic recording media with even higher coercivity are currently being developed, and in order to record sufficiently on such high-coercivity magnetic recording media, it is necessary to have a saturation magnetic flux density of 1.5 Tesla or more. It is said that a magnetic material for magnetic helad core is necessary (for example, Hitachi 1 Vol. 49 No. 8
~9 pages].

An example of a material with a high saturation magnetic flux density is pure iron with a density of 2.2 Tesla. However, pure iron has low magnetic permeability, so it cannot be used as a magnetic head material. Therefore, iron carbide-based multilayer films have been studied, and soft magnetic thin films that have both high saturation magnetic flux density and magnetic permeability have been reported [for example, R Journal Op Apollide Physics Journal
of Applied Physics J Vo 1.
63. No, 8. April.

1988, pp, 3203-3205; r Japan Society of Applied Magnetics JVOI, 12. No. 3, 1988゜pp, 46
0-464]. However, it has not been put into practical use due to problems such as corrosion resistance.

Problems to be Solved by the Invention As mentioned above, there has been a problem in that magnetic materials having a saturation magnetic flux density of 1.5 Tesla or more have not been able to have both high durability and magnetic permeability.

In view of the above problems, the present invention provides a soft magnetic thin film having both high durability and magnetic permeability, and a high saturation magnetic flux density, and a magnetic head using the same.

Means for Solving the Problems In order to solve the above problems, the soft magnetic thin film of the present invention has iron layers and iron carbide layers having a positive magnetostriction constant in the range of 04 degrees arranged alternately, and Single layer thickness of iron is 3~800mm
nm, and the thickness of the iron single layer is 0.5 to 60 nm.

Effect of the present invention With the above-described structure, even if enough carbon is added to the iron carbide layer to provide sufficient durability at the expense of sacrificing the saturation magnetic flux, sufficient saturation magnetic flux can be maintained due to the presence of the pure iron layer. The instability of the layer can be compensated for by the iron carbide layer sandwiching it. The negative magnetostriction of the pure iron layer and the positive magnetostriction of the iron carbide layer roughly cancel each other out, making it possible to have sufficiently high magnetic permeability.

EXAMPLE Hereinafter, a soft magnetic thin film according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing the layered structure of iron carbide and pure iron in soft magnetic thin films of first and second embodiments of the present invention. In Figure 1, 11 is iron carbide and 12 is pure iron.

The soft magnetic yJ film of this example was produced using a three-target high-frequency magnetron sputtering device, and the film thickness of each layer was controlled by the sputtering time, and the total film thickness was 2 nm regardless of the film thickness of each layer. Adjust the number of layers to achieve the desired level.

Furthermore, all the soft magnetic thin films of this example were annealed at 320° C. for 1 hour after film formation.

The characteristics of the soft magnetic III film having the above structure will be explained below using Table 1 and FIGS. 3 to 11.

First, Table 1 shows the soft magnetic thin film of this example in which the thickness of the pure iron layer is 3 nm, the thickness of the iron carbide layer is 30 nm, and the carbon concentration of the iron carbide layer is 9% in molar percentage, and the soft magnetic thin film of pure iron. It is a table comparing the characteristics of a layer film and a single layer film of iron carbide having a carbon concentration of 3% and 27%, respectively, in terms of molar percentage.

In Table 1, the relative magnetic permeability is the value at 20 MHz, and the weather resistance is expressed as the ratio of the saturation magnetic flux density of the thin film after being left in 3% salt water spray for 200 hours to the saturation magnetic flux density before being left.

(Left below) Table 1 As is clear from Table 1, this example realized a soft magnetic thin film that has high saturation magnetic flux density, magnetic permeability, and durability that cannot be obtained with a single layer film. can do.

3, 4, and 5, the thickness of the pure iron layer is fixed at 3 nm, and the thickness of the iron carbide layer is varied from 0.7 nm to 20 nm.
FIG. 3 is a diagram showing changes in saturation magnetic flux density, coercive force, and relative magnetic permeability at 20 MHz when changing it to 00 nm.

At this time, the carbon concentration in the iron carbide layer is 24% in mole percentage, and the magnetostriction constant when the same layer is made as a single layer is 5.
．． It is 2×104.

As is clear from FIGS. 3, 4 and 5, 3n
When a pure iron layer of m and an iron carbide layer with a carbon concentration of 24% in molar percentage are laminated, the thickness of the iron carbide layer is 3 to 800 n.
A magnetic thin film with good soft magnetic properties can be realized when m.

6, 7, and 8, the thickness of the iron carbide layer is fixed at 30 nm, and the thickness of the pure iron layer is varied from 0.5 nm to 2.
FIG. 2 is a diagram showing changes in saturation magnetic flux density, coercive force, and relative magnetic permeability at 20 MHz when changing the magnetic flux density to 000 nm. At this time, the carbon concentration in the iron carbide layer is 24% in molar percentage.
, and the magnetostriction constant when the same material is made in a single layer is:
It is 5.2×104.

As is clear from FIGS. 6, 7, and 8, when an iron carbide layer with a thickness of 30 nm and a carbon concentration of 24% in molar percentage and a layer of pure iron are laminated, pure iron The film thickness of the debris is 0.
When the thickness is 5 to 60 nm, a magnetic thin film with good soft magnetic properties can be realized.

Figures 9 and 10 show the magnetostriction constant of a single layer of iron carbide with a thickness of 1100n when the carbon concentration in the iron carbide is changed, an iron carbide layer with the same thickness of 1100n, and pure iron with a thickness of 3nm, respectively. It is a figure showing the relationship between coercive force and magnetic permeability of a laminated film with layers.

As is clear from FIGS. 9 and 10, the film thickness is 10
When a 0 n rn iron carbide layer and a 3 nm pure iron layer are laminated, the magnetostriction constant of the iron carbide layer is positive, especially from 0.5 to 8.0.
When X104, a magnetic thin film with good soft magnetic properties can be realized.

Figure 11 shows that each thin film, in which the thickness of pure iron scrap was fixed at 3 nm and the thickness of the iron carbide layer was varied from 0.7 nm to 2000 nm, was left in a 3% salt water spray for 200 hours.
FIG. 3 is a diagram showing the ratio of the saturation magnetic flux density of each thin film before being left to stand and the saturation magnetic flux density of each thin film after being left to stand. At this time, the carbon concentration in the iron carbide layer is 24% in mole percentage, and the magnetostriction constant when the same layer is made as a single layer is 5.2x104.

As is clear from FIG. 11, when pure iron scrap with a thickness of 3 nm and an iron carbide layer with a carbon concentration of 24% in molar percentage are laminated, good weather resistance is achieved when the thickness of the iron carbide layer is 3 nm or more. It is possible to realize a magnetic thin film with

From the above results, it is clear that iron layers and iron carbide layers with a positive magnetostriction constant and a C concentration range are arranged alternately, and that each iron carbide layer has a thickness of 3 to 800 nm, and that each pure iron layer has a thickness of 3 to 800 nm. Saga 0.5
By setting the thickness to 60 nm, it is possible to provide a soft magnetic thin film with high saturation magnetic flux density that has both high durability and magnetic permeability.

A magnetic head according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 12 is a cross-sectional view of a portion of a magnetic head according to a second embodiment of the present invention. In FIG. 12, numeral 31 is a ceramic substrate whose surface has been sufficiently polished and cleaned. 32 is a soft magnetic thin film of the present invention, which is a lamination of an iron carbide layer with a thickness of 30 nm and a carbon concentration of 24% in molar percentage, and a layer of pure iron with a thickness of 5 nm, and the number of laminated layers is iron carbide. 91 layers, 9 pure iron layers
It is 01J. Note that the soft magnetic thin film 32 is formed on the ceramic substrate 3.
1 by sputtering, and then patterned into a predetermined magnetic core shape by ion milling, wet etching, or the like. 33, 34
．． 35 is a gap material such as 5i02, an organic insulating layer, and a conductor coil, which are sequentially deposited on the entire surface by a film forming method such as sputtering method, and then patterned into a predetermined shape by ion milling method or wet etching method. It is. 36 has the same soft magnetic thin film as 31 formed in the same number of layers. 37 is a protective film A
An insulating layer such as l2O2 is deposited over the entire surface.

The deposit shown in FIG. 12 constructed as described above is cut into a predetermined shape, and the head tip side 39 is polished to form a magnetic gap 38 to form one thin film magnetic head.

The magnetic properties of the above magnetic head were measured using a thin film formed on another substrate under the same conditions, and the saturation magnetic flux density was 1.
．． 92 Tesla, coercive force in the direction of difficult magnetization is 0.130e,
It was confirmed that the relative magnetic permeability at 29 MHz was 3900, showing excellent characteristics.

Furthermore, when the electromagnetic conversion characteristics of the above head were compared with those of a conventional cobalt-based amorphous alloy thin film head, it was confirmed that the reproduction output was improved by about 25%. Also, Celsius 60゛C1 relative humidity 9
When the reproduction output of a conventional head using a cobalt-based amorphous alloy thin film was left in a room temperature and humidity chamber at 0% until the reproduction output decreased by 30%, there was almost no change in the reproduction output of the magnetic head of this example. was not seen.

As described above, according to this example, by using the soft magnetic thin film of the present invention in the magnetically permeable layer, the saturation magnetic flux density is 1.92.
It is possible to provide a magnetic head that has a high magnetic permeability and corrosion resistance as high as Tesla.

A soft magnetic thin film according to a third embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing a layered structure of iron carbide, pure iron, and a layer of nonmagnetic material such as silicon oxide in a soft magnetic thin film according to a third embodiment of the present invention. In FIG. 2, 21 is iron carbide, 22 is pure iron, and 23 is a nonmagnetic material such as silicon oxide.

In this example, an iron carbide layer with a film thickness of 30 m and a carbon concentration of 24% in molar percentage, a pure iron layer with a film thickness of 5 nm, and a silicon oxide layer with a film thickness of 3 nm are each made of 90 m of iron carbide. A thin-film magnetic head that is exactly the same as the second embodiment is formed by laminating layers one by one, and when comparing the electromagnetic conversion characteristics with the thin-film head of the second embodiment, the reproduction output in the high frequency region is increased by an additional 20%.
It was confirmed that there was an improvement.

Furthermore, when a conventional head using a cobalt-based amorphous alloy thin film was left in a normal temperature and humidity chamber at a relative temperature of 90% at 60° Celsius until its reproduction output decreased by 30%, the magnetic head of this example also showed As with the head of the second example, almost no change was observed in the reproduction output.

Effects of the Invention As described above, the present invention provides a method in which iron layers and iron carbide layers having a positive magnetostriction constant and a C concentration range are arranged alternately, and the thickness of the single iron carbide layer is 3 to 800 nm. , the thickness of the iron single layer is 0
．． By having a configuration of 5 to 60 nm,
Even if enough carbon is added to iron carbide scrap to provide sufficient durability at the expense of saturation magnetic flux, sufficient saturation magnetic flux can be maintained due to the presence of pure Y and N, and the instability of pure iron scrap also prevents this. It is captured by the iron carbide layer. Furthermore, the negative magnetostriction of the pure iron layer and the positive magnetostriction of the iron carbide layer cancel each other out, so that it can also have a sufficiently high magnetic permeability. That is, it is possible to realize a soft magnetic thin film with high saturation magnetic flux density that has both high durability and magnetic permeability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the layered structure of iron carbide and pure iron in a soft magnetic thin film according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the carbonization in the soft magnetic thin film according to the first embodiment of the present invention. Figure 3 is a cross-sectional view showing the layered structure of iron and pure iron, and Figure 4 is a diagram showing the relationship between the thickness of the iron carbide layer and the saturation magnetic flux density when the thickness of pure iron stone is fixed. Figure 5 shows the relationship between the iron carbide layer and coercive force when the thickness of pure iron scrap is fixed, and Figure 5 shows the film thickness and relative permeability of the iron carbide fan when the thickness of pure iron scrap is fixed. Figure 6 is a diagram showing the relationship between the thickness of the pure iron layer and the saturation magnetic flux density when the thickness of iron carbide scrap is fixed, and Figure 7 is a diagram showing the change in the saturation magnetic flux density.
The figure shows the relationship between the thickness of pure iron scrap and coercive force when the thickness of iron carbide scrap is fixed. Figure 8 shows the film of pure iron scrap when the thickness of iron carbide layer is fixed. Figure 9 shows the relationship between thickness and relative magnetic permeability at 20 MHz. Figure 9 shows the magnetostriction constant of a single layer of iron carbide of 100100n when the carbon concentration in iron carbide is changed, and the magnetostriction constant of a single layer of iron carbide of the same thickness of 1100n. Figure 1O shows the relationship between the coercive force and the coercive force of a laminated film of a pure iron layer with a thickness of 3 nm.
The magnetostriction constant of a single layer of iron carbide with a thickness of 1100 nm, the iron carbide layer with the same thickness of 1100 nm, and the film J! Product FipIi with f-3 nm pure iron layer
Figure 11 shows the relationship between magnetic permeability and magnetic permeability of 3.
Figure 12 shows the ratio of the saturation magnetic flux density of each thin film before being left to the saturation magnetic flux density after being left in salt water spray for 200 hours. FIG. 3 is a cross-sectional view of a portion of the magnetic head. 11... Iron carbide, 12... Pure iron, 21
...Iron carbide, 22...Pure iron, 23...
... Non-magnetic material such as silicon oxide, 31 ... Ceramic substrate, 32 ... Soft magnetic thin film of the present invention,
33...Gump material, 34...Group/organic insulating layer, 35...Conductor coil, 36...31
Same soft magnetic thin film as 37...protective film, 38...
...Magnetic gap, 39...Head tip. Name of agent Patent attorney Shigetaka Awano 1 person ε condyle 1% snow No. 3 Fig. 4 IO100/σ0ρ Carbonization 1 thickness (gm) Ward \ N Iron carbide layer thickness (Qippao) Drainage map Carbonization Qin layer moisture (4 慴9 Pure iron layer thickness (1 place p Section 8 Figure 1 O/θO Number (to”) Transparent strain constant (jO″p 11th factor 12I711 Carbonization tvIF4 (desk)

Claims (4)

[Claims] (1) A soft magnetic thin film characterized by alternately laminating iron carbide layers and iron layers. (2) Iron layers and iron carbide layers with a positive magnetostriction constant and a C concentration range are arranged alternately, and each iron carbide layer has a thickness of 3 to 800 nm, and each pure iron layer has a thickness of 3 to 800 nm. 0.5-60nm
A soft magnetic thin film characterized by: (3) Claim (1) or (
A magnetic head characterized in that the soft magnetic thin film according to any one of 2) is used. (4) The magnetic head according to claim (4), characterized in that reproduction efficiency is increased by inserting a nonmagnetic layer into the soft magnetic thin film according to either claim (1) or (2). .