JPH10247607A - Manufacture of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a magnetic recording medium of improved magnetic efficiency which can be manufactured by a simplified process. SOLUTION: In this manufacturing method of magnetic recording medium provided on the substrate 1 of the magnetic recording medium with a yoke 3, where magnetic flux passes through almost in the same direction as the surface of a substrate, and a magnetic recording layer 4 to be formed on the upper surface of the yoke 3, an alloy film, consisting of the integrated and inseparable yoke 3 and the magnetic recording layer 4, are formed on the substrate 1 using a sputtering device provided with two or more kind of alloy targets of different components and by changing the sputtering rate from each target according to the lapse of time. In this case, the alloy film consisting of the magnetic recording layer 4 and the yoke layer 3 has a crystal structure selected from Th2 Zn17 , Th2 Ni17 , TbCu7 , ThMn12 , R3 (Fe, M)29 type, and besides, a protective film 8 is coated on the upper surface of the magnetic recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording device which is an external storage device of a computer and a method of manufacturing a magnetic recording medium used for storing music and images.

[0002]

2. Description of the Related Art Magnetic recording media are widely used not only as recording media for music and image data but also as external storage devices for computers. Considering, for example, an external storage device of a computer, in recent years, various methods have been devised in a recording method and a recording medium in order to enable high-density recording in a magnetic recording device. As an example, as a recording method, a perpendicular recording method has been proposed with respect to the conventional longitudinal recording. Further, in the recording medium, a two-layer or three-layer medium having different materials and magnetic properties is used in part.

[0003]

In the case of a perpendicular recording medium in which a soft magnetic permalloy or the like magnetic film is formed as a lower layer and a hard magnetic Co—Cr based film is formed as an upper layer, the hard magnetic film is Due to the influence of the crystallinity of the lower layer, it is difficult to have perpendicular anisotropy with respect to the film surface. Therefore, the film is formed by strictly controlling the alloy composition and sputtering conditions. Alternatively, a thin buffer layer is provided at the interface between the upper layer and the lower layer in order to eliminate the influence of the lower layer. In any case,
Not only does this increase the number of steps, but also significantly lowers the magnetic efficiency, which is a factor that lowers the recording / reproducing efficiency, the signal-to-noise ratio, and impairs the stability of the recording magnetization state. The present invention has been made in view of the above-mentioned problems, and its purpose is to
An object of the present invention is to provide a novel magnetic recording medium manufacturing method for the purpose of improving magnetic efficiency and simplifying a manufacturing process.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a yoke layer on a substrate of a magnetic recording medium, the magnetic flux passing in substantially the same direction as the substrate surface, and an upper surface of the yoke layer. In a method for manufacturing a magnetic recording medium having a magnetic recording layer formed on a substrate, a sputtering apparatus equipped with two or more alloy targets having different component compositions is used, and the sputtering rate from each target is changed over time. hand,
Provided is a method for manufacturing a magnetic recording medium in which an alloy film composed of an inseparable yoke layer and a magnetic recording layer is formed on the substrate.

The principle of the structure of a magnetic recording medium according to the present invention in which a magnetic recording layer and a yoke layer are integrally formed is as follows. For example, by sputtering, S
forming an Sm ₂ Fe ₁₇ film using an m-Fe target,
An Fe—Ti target is added on the way, and binary simultaneous sputtering with Sm—Fe is performed to form an SmFe ₁₁ Ti film as an upper layer. In this case, C-axis of the soft magnetic Sm ₂ Fe ₁₇ crystal form so that the substrate surface and perpendicular to, the hard magnetic SmFe ₁₁
The Ti upper layer is formed so that the crystal C axis is parallel to the substrate surface, and therefore, the easy magnetization direction of the hard magnetic recording layer is parallel to the film surface. In addition, by appropriately selecting the crystal structure and the component composition of the alloy, it is possible to manufacture a magnetic film in which both hard and soft magnetism and anisotropy are controlled.

The film forming method of the present invention uses a binary sputtering method. As for the components of the alloy film, one or more rare earth elements of the lanthanide genus, iron, and the element M
(Co, Ni, Al, Si, Ti, V, Cr, Mn, Z
r, Nb, Mo, Ga, Sn, Hf, Ta, and W) as an essential element. With respect to the composition range, when the rare earth element is less than 3%, the coercive force is small and the magnetic recording layer is required. High coercive force cannot be obtained. On the other hand, if it exceeds 15%, the saturation magnetization decreases, and the rare earth content increases, so that the oxidation resistance of the film is impaired. Further, by adding one or more elements M, the crystal structure of the alloy can be stabilized and the magnetic characteristics can be adjusted. However, when the total amount of the element M is 0.
If it is less than 02%, the effect of adjusting the magnetic properties is hardly observed, while if it exceeds 20%, the original crystal structure of the alloy cannot be maintained, and the magnetic properties are significantly impaired.

The alloy film of the present invention is made of Th ₂ Zn ₁₇ , T
h ₂ Ni ₁₇ , TbCu ₇ , ThMn ₁₂ , R ₃ (Fe,
M) It is constituted by selecting various compounds such as type ₂₉ . For example, on the C-plane (001) of an alloy having a composition of Sm ₂ Fe ₁₇ having a crystal structure of Th ₂ Zn ₁₇ , Sm ₂ Fe ₁₇ Ti ₂ containing Ti is added.
When an upper alloy film having a composition is formed, the upper layer has a ThMn ₁₂ type crystal structure and its C axis is parallel to the film surface due to the advantage of crystal stacking. In another example, N having a ThMn ₁₂ structure
An upper layer film of NdFe ₁₀ VMo composition having the same crystal structure is formed on the C-plane (001) of the alloy having dFe ₁₁ V composition. In this case, the lower layer shows intermediate magnetism between soft magnetism and hard magnetism,
The upper layer exhibits hard magnetism and has an easy axis of magnetization perpendicular to the film surface.

Since rare-earth iron-based alloys are generally chemically active, in practice, a protective film such as silicon oxide, carbon, or a polymer for preventing oxidation or wear is deposited on the upper part of the alloy film. Let me. The magnetic recording medium configured as described above has excellent smoothness because there is no disturbance at the boundary between the upper and lower layers, and also has no magnetic gap that is observed in the conventional two-layer film. It has high reproduction characteristics and a high signal-to-noise ratio, and is excellent in stability of the recording magnetization state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial sectional view of a magnetic recording medium according to the present invention. In FIG. 1, reference numeral 1 denotes a substrate made of glass or the like. On the upper surface of the substrate 1, a magnetic medium layer 2 is formed. The magnetic medium layer 2 comprises a yoke layer 3 attached on a substrate, a magnetic recording layer 4 on the surface, and a boundary portion 5 formed therebetween.

The substrate 1 is made of SiO ₂ glass having high mechanical strength and small expansion and contraction due to temperature change. The yoke layer 3 is made of a soft magnetic material or a ferromagnetic material whose easy axis of magnetic anisotropy is aligned in the plane direction of the substrate 1, and both pass a magnetic flux in the same direction as the plane of the substrate 1. It is configured to be able to. When the yoke layer 3 is made of a soft magnetic material or when the yoke layer 3 is made of a ferromagnetic material whose axis is aligned in the plane direction of the substrate 1,
Anisotropy in a direction perpendicular to the plane of the substrate 1 can be provided, and when the yoke layer 3 is made of a soft magnetic material, anisotropy can be provided in the plane direction of the substrate 1. The magnetic recording layer exhibits excellent hard magnetic characteristics. The boundary portion 5 is not clearly separated from the yoke layer 3 and the magnetic recording layer 4 by a plane, but is in a state in which both are intermingled. The boundary between the two layers is formed by a configuration in which the composition of the other layer gradually decreases, and the details will be described later. The thickness of the magnetic recording layer is approximately 2 to 50% of the thickness of the entire yoke layer at the boundary between the magnetic recording layers.

The substrate 1 can be made of glass as described above. Alternatively, as shown in FIG. 2, the substrate 6 can be made of aluminum. In this case, the space between the substrate 6 and the magnetic medium layer 2 is formed. It is preferable to form a base film 7 made of a non-magnetic metal to repair defects on the surface of the aluminum substrate and absorb physical strain generated between the magnetic medium layer 2 and the substrate 6 at the same time. Further, the substrate 1 can be made of silicon.

[0012]

【Example】

Embodiment 1 FIG. After performing initial sputtering in an argon gas using an Sm-Fe target, Fe-Ti
With the addition of a target, 2
8.3 at% on silicon substrate
An alloy film having an Sm-5.4 at% Ti-residual Fe composition was formed to obtain a sample (1) of the present invention. In addition, after a permalloy film is formed on a silicon substrate using a Ni—Fe target, Co—C is formed using a Co—Cr—Ta target.
An r-Ta alloy film was formed as a comparative sample (3), and the lower layer of the film had a Th ₂ Zn ₁₇ type crystal structure, an approximate composition of Sm ₂ Fe ₁₇ , and the C axis of the crystal. Was formed perpendicular to the substrate surface. On the other hand, the upper layer has a ThMn ₁₂ type crystal structure, and the approximate composition is SmFe ₁₁ Ti,
The C axis of the crystal was formed parallel to the substrate surface. In addition, as a result of observing the microstructure of the upper layer, it was found that the Sm having a diameter of 20-50 nm
-Ti-Fe main phase of about 10nm to around Fe ₂ Ti nonmagnetic subphase was observed. Further, the lower layer showed soft magnetism, while the upper layer showed hard magnetism, and its anisotropic direction was parallel to the film surface. As shown in FIG. 5, the coercive force of this sample (1) was 2630 Oe for the upper layer and 1.1 Oe for the lower layer.

Using the sample (1) as a medium, recording / reproducing characteristics were evaluated using a single pole head generally used in perpendicular magnetic recording. The track width was 10 μm, the number of coil turns was 26 turns, and the peripheral speed was 10 m / s. As a result, the sample (1) has a reproduction output 74% higher than that of the conventional comparative sample (3), and has a D _{50 which is} a measure of high recording density.
Was found to be 38% higher. Furthermore, the SN ratio is -44
A good value was shown in dB.

In this embodiment, as shown in FIG. 3, the lower layer film is a yoke layer 3 which exhibits soft magnetism and allows a magnetic flux to pass. The upper layer film forms the magnetic recording layer 4 which is hard magnetic and has anisotropy in the direction parallel to the film surface. Further, the yoke layer 3 and the magnetic recording layer 4 are formed integrally and inseparably, and their boundary portions 5
Has a configuration in which the composition of the other layer gradually decreases toward one of the layers. 8 is a protective film.

Embodiment 2 FIG. When performing initial sputtering in argon gas using two types of targets, Nd-Fe and Fe-B, the sputtering rate from the Fe-B target is increased with time, and a film is formed. One on top
An alloy film having a composition of 3.4 at% Nd-8.5 at% B-remaining Fe was formed to obtain a sample (2) of the present invention. This membrane
The lower layer had a TbCu ₇ type crystal structure, and its C axis was formed perpendicular to the substrate surface. On the other hand, the upper layer film containing boron had an Nd ₂ Fe ₁₄ B type crystal structure, and its C axis was formed perpendicular to the substrate surface. The lower film showed soft magnetism, and the upper film showed hard magnetism and had anisotropy in the direction perpendicular to the film surface. The coercive force of this sample (2) was
At 10 Oe, the lower layer was 0.8 Oe.

In this embodiment, as shown in FIG. 4, an upper layer film is formed of a magnetic recording layer 4 which becomes hard magnetic and exhibits anisotropy in a direction perpendicular to the film surface. Become. The intermediate boundary portion 5 has a configuration in which the composition of the other layer gradually decreases toward one of the layers.

Embodiment 3 An NdFe ₇ film is formed on a substrate surface by using a Nd—Fe target by sputtering, and
An e-B target is added and binary simultaneous sputtering is performed to form an Nd ₂ Fe ₁₄ B film as an upper layer. At this time, the soft magnetic NdFe ₇ crystal is formed such that the C plane (001) is parallel to the substrate surface. The hard magnetic Nd ₂ Fe ₁₄ B upper layer exhibits anisotropy in the direction perpendicular to the substrate surface by being formed so that the C axis of the crystal is perpendicular to the substrate surface. Therefore,
As shown in FIG. 4, a soft magnetic yoke layer 3 is formed on the lowermost layer, and a ferromagnetic magnetic recording layer 4 showing anisotropy in a direction perpendicular to the substrate surface is formed on the uppermost layer. The intermediate boundary portion 5 has a configuration in which the composition of the other layer gradually decreases toward one of the layers. The coercive force of this sample was 2530 Oe in the upper layer and 0.9 Oe in the lower layer.

Although the present invention has been described with reference to the above-described embodiments and examples, various modifications and applications are possible within the scope of the present invention, and these modifications and applications are excluded from the scope of the present invention. It does not do.

[0019]

As described above, according to the present invention, a yoke layer for passing a magnetic flux in substantially the same direction as the substrate surface on a substrate of the magnetic recording medium, and a magnetic recording medium formed on the upper surface of the yoke layer A method for manufacturing a magnetic recording medium comprising:
An alloy comprising an inseparable yoke layer and a magnetic recording layer on the substrate by using a sputtering apparatus equipped with two or more alloy targets having different component compositions and changing the sputtering rate from each target over time. Since the film is formed, there is no need to provide a buffer layer between the magnetic recording layer and the yoke layer as in the conventional manufacturing method. Therefore, it has excellent magnetic properties not found in the conventional two-layer film structure, has no disturbance at the boundary surface, has excellent smoothness, and has no magnetic gap. Effective for improvement. Further, since there is no need to form two types of magnetic layers, the manufacturing process can be simplified.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a magnetic recording medium of the present invention.

FIG. 2 is a partial cross-sectional view of another magnetic recording medium of the present invention.

FIG. 3 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 4 is a sectional view showing second and third embodiments of the present invention.

FIG. 5 is a comparative chart of the present invention and a conventional example.

[Explanation of symbols]

 1 ... substrate 2 ... magnetic medium layer 3 ... yoke layer 4 ... magnetic recording layer 5 ... boundary 6 ... substrate 7 .... Undercoat 8 ... Protective film

Claims (7)

[Claims] 1. A method of manufacturing a magnetic recording medium, comprising: a yoke layer on a substrate of a magnetic recording medium, the magnetic flux passing in substantially the same direction as the surface of the substrate; and a magnetic recording layer formed on an upper surface of the yoke layer. In the method, using a sputtering apparatus equipped with two or more alloy targets having different component compositions, changing the sputtering rate from each target with the passage of time, and forming an inseparable yoke layer and a magnetic recording layer on the substrate. A method for manufacturing a magnetic recording medium for forming an alloy film comprising: 2. The method according to claim 1, wherein at least one of the two or more alloy targets has an alloy composition of a rare earth metal and iron. 3. The method according to claim 2, wherein the rare earth metal contained in the alloy is Sm. 4. The method according to claim 2, wherein the rare earth metal contained in the alloy is Nd. 5. At least one of the alloy targets includes Co, Ni, Al, Si, Ti,
V, Cr, Mn, Zr, Nb, Mo, Ga, Sn, H
at least one of f, Ta, and W for 0.02-20 at
2. The method for manufacturing a magnetic recording medium according to claim 1, wherein% is included. 6. An alloy film comprising the magnetic recording layer and the yoke layer is made of Th ₂ Zn ₁₇ , Th ₂ Ni ₁₇ , TbCu ₇ , Th.
2. The method according to claim 1, wherein the magnetic recording medium has a crystal structure of any one of Mn ₁₂ and R ₃ (Fe, M) ₂₉ types. 7. The method for manufacturing a magnetic recording medium according to claim 1, wherein a protective film is provided on an upper surface of said magnetic recording layer.