JP2002269717A - Perpendicular magnetic recording medium and manufacturing method for perpendicular magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise of a perpendicular magnetic recording medium formed by using a rare earth-transition metal amorphous magnetic alloy film as a perpendicularly magnetized film. SOLUTION: The perpendicular magnetic recording medium has a laminated structure having a substrate 2, the perpendicularly magnetized film 3 formed on the substrate 2 and a protective film 4 formed on the perpendicularly magnetized film 3. The perpendicularly magnetized film 3 has the magnetic alloy consisting essentially of a rare earth metal-transition metal alloy as a base material and is a rare earth-transition metal system granular thin film wherein the particles of a non-magnetic material are dispersed in the base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a perpendicular magnetic recording medium used as a magnetic disk or the like in a storage device such as a computer, and a method of manufacturing a perpendicular magnetic recording medium.

[0002]

2. Description of the Related Art In recent years, hard disk drives are used not only for personal computers and workstations but also for hard disk drives.
It has also been used for V equipment and the like, and is required to have a large capacity and a small size. Magnetic disks are required to have a higher recording density. However, in order to achieve a high recording density with the widely used longitudinal magnetic recording method, there is a problem of thermal fluctuation of recording magnetization due to miniaturization of recording bits and a high coercive force that may exceed the recording capability of the recording head. Problems arise. Therefore, a perpendicular magnetic recording system is being studied as a means for resolving these problems and greatly increasing the areal recording density.

As one of the perpendicular magnetic recording media for realizing the perpendicular magnetic recording system, a perpendicular two-layer film comprising a soft magnetic film having a high magnetic permeability and a perpendicular magnetic film having a high perpendicular anisotropy has been proposed.

[0004] Hereinafter, referring to FIG.
The configuration of the layered medium will be described. FIG. 4 is a schematic substrate sectional view of a conventional perpendicular magnetic recording medium. A conventional perpendicular magnetic recording medium 100 is formed by sequentially forming a soft magnetic film 102, a perpendicular magnetization film 103, and a protective film 104 on a substrate 101. For example, the permalloy (N
A cobalt-chromium (Co-Cr) alloy film is used for the i-Fe) film and the perpendicular magnetization film 103, and carbon (C) is used for the protection film 104, respectively. Here, the soft magnetic film 102 operates as a part of the recording head. The magnetic field from the main magnetic pole of the magnetic head passes through the soft magnetic film 102 and the auxiliary magnetic pole to form one closed magnetic path. With such a configuration, the perpendicular magnetic field in the medium can be strengthened, and the recording sensitivity can be improved.
ol. 8, No. 1, 1984, p. 17).

[0005] In the perpendicular magnetic recording system,
There is a problem that noise is large in DC erasure (saturated remanent magnetization) of a perpendicular magnetic recording medium, and a reverse magnetic domain formed in the recording medium is considered as a noise source. In order to reduce the noise caused by the reverse magnetic domains, it is necessary to reduce the reverse magnetic domains and reduce the number of the reverse magnetic domains. Reducing the number of reverse magnetic domains corresponds to increasing the squareness ratio (the ratio of the residual magnetization to the saturation magnetization) in the MH (magnetization-magnetic field) loop perpendicular to the substrate surface of the perpendicular magnetic recording medium. are doing.

As a perpendicular magnetization film having a large squareness ratio, a rare earth metal-transition metal (RE-T
M) -based amorphous alloy films are known. Since it has an amorphous structure, there is little problem of thermal fluctuation due to finer particles, and since it has a large perpendicular magnetic anisotropy, it has attracted attention as a perpendicular magnetic recording medium.

[0007]

However, Co-
Since the microstructure of the Cr-based alloy is an inhomogeneous structure consisting of a ferromagnetic region and a non-magnetic region, pinning of domain wall motion during magnetization reversal was possible, whereas an RE-TM-based amorphous alloy film was Since the whole film is a continuous film of a uniform ferromagnetic material, there is no pinning site of the domain wall, and the magnetic domain becomes unstable.

As described above, in the RE-TM-based amorphous alloy film, the recording magnetization transition region becomes unstable, and transition noise increases with the recording density. is there.

Accordingly, an object of the present invention is to make use of the advantage of the RE-TM film that suppresses DC noise by a high squareness ratio, suppress transitional noise, and realize a high-density perpendicular magnetic recording medium. And a method of manufacturing a perpendicular magnetic recording medium.

[0010]

In order to achieve the above object, a perpendicular magnetic recording medium according to the present invention comprises a substrate, a perpendicular magnetic film provided on the substrate, a protective film provided on the perpendicular magnetic film. Wherein the perpendicular magnetization film is a granular thin film composed of a magnetic alloy containing a rare earth metal-transition metal alloy as a main component and a nonmagnetic material, and a rare earth metal-transition metal alloy as a main component. The magnetic alloy is a base material of the granular thin film, and the nonmagnetic material is particles dispersed in the base material.

According to the above configuration, the nonmagnetic material dispersed in the continuous structure magnetic film can be used as the pinning site of the domain wall. In addition, since there is basically no grain boundary in an amorphous structure, an irregular zigzag structure in a magnetization transition region depending on a crystal grain size can be minimized.
For this reason, noise can be reduced.

The perpendicular magnetic film of the perpendicular magnetic recording medium of the present invention contains at least one of Tb, Gd, and Dy as a rare earth metal, and at least one of Fe and Co as a transition metal. In addition, as a non-magnetic material, Si-
O, Al-O, Zr-O, Mg-O, Si-N, Si-
It is characterized in that at least one of C and C is included.

Further, the method of manufacturing a perpendicular magnetic recording medium according to the present invention comprises a step of forming a non-magnetic material in an island structure on a substrate or a base film provided on the substrate; And a step of forming a magnetic alloy thin film containing a metal alloy as a main component.

According to this method, a perpendicular magnetization film in which non-magnetic particles are dispersed can be formed in a rare earth metal-transition metal magnetic alloy thin film.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a substrate showing an example of a configuration of a perpendicular magnetic recording medium according to an embodiment of the present invention. The perpendicular magnetic recording medium 1 of the present invention is obtained by forming a rare earth-transition metal based granular perpendicular magnetization film 3 and a protective film 4 on a substrate 2 in this order. FIG.
FIG. 3 is a schematic view of the fine structure of the perpendicular magnetization film in the perpendicular magnetic recording medium of the present invention. The particles of the non-magnetic material 6 are dispersed in the rare-earth metal-transition metal based magnetic alloy 5.

[0016]

Next, specific examples of the present invention will be described.

(Embodiment 1) This embodiment is one of the embodiments of the perpendicular magnetic recording medium according to the present invention. FIG. 3 is a cross-sectional view of the substrate showing the configuration of the perpendicular magnetic recording medium of this embodiment. The perpendicular magnetic recording medium 7 of the present embodiment includes a substrate 8 having a diameter of 65 mm.
And Ni-Fe with a thickness of 500 nm formed on the substrate 8
And a Tb formed on the soft magnetic film 9
A rare earth-transition metal-based granular perpendicular magnetization film 10 made of Fe—Co and SiO 2, and a carbon protective film 11
And is formed as a laminated structure having:

Hereinafter, a method for manufacturing the perpendicular magnetic recording medium 7 of this embodiment will be described. First, a Ni-F film having a thickness of 500 nm is formed on a substrate 8 having a diameter of 65 mm by sputtering.
A soft magnetic film 9 made of an e film was formed. Next, an 80 nm-thick Tb-F film is formed on the soft magnetic film 9 by a simultaneous sputtering method using a Tb-Fe-Co and SiO2 target.
A rare earth-transition metal-based granular perpendicular magnetization film 10 made of e-Co and SiO2 was formed at room temperature. Si
The volume fraction of O2 was controlled by electric power applied to the target, and was set to 5%. Further, an 8 nm-thick carbon protective film 11 was formed on the rare earth-transition metal-based granular perpendicular magnetization film 10 to produce a perpendicular magnetic recording medium of Example 1. On the other hand, a perpendicular magnetic recording medium in which a perpendicular magnetic film having a thickness of 80 nm was formed using only the Tb-Fe-Co target was used as a comparative example.

(Embodiment 2) This embodiment is one of embodiments of a method for manufacturing a perpendicular magnetic recording medium according to the present invention. The basic medium configuration is the same as that of the first embodiment shown in FIG. 3, except that the rare-earth / transition metal-based granular perpendicular magnetization film 10 is used.
Are different from each other.

Hereinafter, a method for manufacturing the perpendicular recording medium of the present embodiment will be described. First, 65m
A soft magnetic film 9 made of a 500 nm thick Ni-Fe film was formed on a substrate 2 having a diameter of m. Next, on the soft magnetic film 9, S
By sputtering using an iO2 target, SiO2 was deposited to a thickness of 1 nm in terms of a deposition time. At this time, it was confirmed by TEM that SiO2 was not a continuous film but an island structure. Subsequently, using a Tb-Fe-Co target,
A Tb-Fe-Co film having a thickness of 10 nm was formed. The above S
The film formation process of i2 and Tb-Fe-Co was repeated eight times,
A rare earth-transition metal based granular perpendicular magnetization film 10 made of iO2 and Tb-Fe-Co was formed. The volume fraction of SiO2 was set to 5%. Further, an 8 nm-thick carbon protective film 11 was formed on the rare-earth / transition metal-based granular perpendicular magnetic film 10 to produce a perpendicular magnetic recording medium of Example 2.

In order to evaluate the perpendicular magnetic recording medium according to the present invention, recording / reproducing characteristics were measured using a single-pole head for recording signals and an MR head for reading signals. Here, the track width of the single pole head is 0.5 μm,
The main pole film thickness was 2 μm. The reproduction track width of the MR head was 0.3 μm, and the distance between the shields was 0.1 μm. The measurement was performed under the conditions of a peripheral speed of 12.7 m / sec, a flying height of 20 nm, and a noise band band of 45 MHz.

Table 1 shows the medium S / N ratio and the medium noise at a recording density of 250 kFRPI based on a comparative example.

[0023]

[Table 1]

The medium of Example 1 had a higher S / N ratio by 1 dB and a lower noise by 1 dB than the medium of the comparative example.
This is because the ratio of the non-magnetic film material in the magnetic film is low, so that the output does not change, but the noise is reduced by the pinning effect and the S / N ratio is improved.

The medium of Example 2 had a higher S / N ratio by 3 dB and a lower noise by 3 dB than the medium of Comparative Example.
This is because there is no reduction in output because the ratio of the non-magnetic film material in the magnetic film is low, and since the non-magnetic material exists as island-shaped particles, the domain wall is more effective than in Example 1. , The noise is reduced and the S / N ratio is improved.

As described above, by using the perpendicular magnetic recording medium and the method for manufacturing the perpendicular magnetic recording medium of the present invention, it is easy to realize a high recording density.

In the above embodiment, the rare earth-transition metal alloy in the rare earth-transition metal-based granular perpendicular magnetization film 10 is a Tb-Fe-Co alloy,
b-Fe, Tb-Co, Gd-Fe, Gd-Co, Gd
-Fe-Co, Dy-Fe, Dy-Co, Dy-Fe-
Co or the like can be used. Further, as a non-magnetic material, S
In addition to iO2, Al-O, Zr-O, Mg-O, Si
-N, Si-C, C and the like can be used.

Further, according to the present invention, a structure in which a soft magnetic film is provided between a substrate and a perpendicular magnetization film, and a thin film for fixing a domain wall of the soft magnetic film between the substrate and the soft magnetic film are provided. The effect does not change even in the configuration.

[0029]

According to the perpendicular magnetic recording medium of the present invention, by dispersing a non-magnetic material in a magnetic film having a continuous structure, a pinning site of a domain wall can be formed and noise can be reduced. Further, since the ratio of the non-magnetic material can be reduced, a decrease in output can be suppressed. With this effect, a perpendicular magnetic recording medium having excellent recording and reproducing characteristics can be realized.

Further, according to the method of manufacturing a perpendicular magnetic recording medium of the present invention, a small proportion of non-magnetic material can be dispersed in the magnetic film in the form of particles. A perpendicular magnetization film can be formed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the configuration of a perpendicular magnetic recording medium according to the present invention.

FIG. 2 is a schematic view showing a fine structure of a perpendicular magnetization film in the perpendicular magnetic recording medium of the present invention.

FIG. 3 is a sectional view showing an example of an embodiment of the configuration of the perpendicular magnetic recording medium of the present invention.

FIG. 4 is a sectional view showing a configuration of a conventional perpendicular magnetic recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Perpendicular magnetic recording medium 2 Substrate 3 Rare earth-transition metal granular perpendicular magnetization film 4 Protective film 5 Rare earth-transition metal magnetic alloy 6 Non-magnetic material 7 Perpendicular magnetic recording medium 8 Substrate 9 Soft magnetic film 10 Rare earth-transition metal granular Perpendicular magnetic film 11 protective film 100 perpendicular magnetic recording medium 101 substrate 102 soft magnetic film 103 perpendicular magnetic film 104 protective film

Claims (3)

[Claims] 1. A perpendicular magnetic recording medium having at least a substrate, a perpendicular magnetic film provided on the substrate, and a protective film provided on the perpendicular magnetic film, wherein the perpendicular magnetic film is made of a rare earth metal A magnetic thin film comprising a transition metal alloy-based magnetic alloy and a non-magnetic material, wherein the rare earth metal-transition metal alloy-based magnetic alloy is a base material of the granular thin film, and is a non-magnetic material. Is a particle dispersed in a base material. 2. The rare earth metal includes one or more of Tb, Gd, and Dy, the transition metal includes one or more of Fe and Co, and the nonmagnetic material includes Si—O, Al
2. The perpendicular magnetic recording medium according to claim 1, comprising at least one of -O, Zr-O, Mg-O, Si-N, Si-C, and C. 3. A step of forming a non-magnetic material into an island structure on a substrate or a base film provided on the substrate, and forming a magnetic alloy thin film containing a rare earth metal-transition metal alloy as a main component. A method for manufacturing a perpendicular magnetic recording medium, wherein the step of forming is performed repeatedly.