JP2000195036A - Magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which can realize improvement of S/N and high packing density. SOLUTION: This recording medium is provided with a plurality of magnetic particles of regular arrangement. Here, in regard to the magnetic particles 5 included in the minimum magnetic recording cell 7, at least four particles are arranged in the longitudinal direction of track, total half-value width in the distribution of distance between the nearest particles is set to ±40% or less of the average distance between the nearest particles and the total half- value width of particle distribution is set to ±20% or less of the average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic recording medium for magnetically recording / reproducing information and a method for manufacturing the same.

[0002]

2. Description of the Related Art Magnetic recording media are widely used as fixed magnetic disk devices in personal data files, communication servers, files for large-scale computers, etc., and are mainly used as magnetic tape devices for individuals and broadcasting stations. Widely used for image and audio files. This is because the magnetization reversal speed, that is, the recording data transfer speed of the magnetic recording medium, which is an aggregate of magnetic crystal grains, is several hundred Mbps.
This is because the above is remarkably fast, and a high recording density of about several tens Gb / in ² can be achieved. Higher recording density is realized by isolating particles by reducing exchange interaction between magnetic particles and miniaturizing magnetic particles. As the amount of information of magnetic recording media continues to increase dramatically toward the multimedia era, higher speed transfer and higher density are expected.

[0003] Among magnetic recording media, the areal recording density of a fixed magnetic disk drive (HDD), which is particularly increasing in recording density, has shown an average annual rate of improvement of 60% or more over the past five years or more. It has reached several Gb / in ² . Improvements in such areal densities include the adoption of a magnetoresistive effect reproducing method, a higher saturation magnetic flux density of the recording pole material, an improvement in narrow track head processing technology, a narrower magnetic head gap, a smaller slider and a higher precision. Machining, servo high accuracy, PR
This is due to the reform and improvement of various elemental technologies such as the introduction of new modulation and demodulation technologies represented by ML. For the magnetic recording medium itself, the head flying height is reduced by smoothing and flattening the surface, the magnetic transition width is reduced by increasing the coercive force and thinning of the magnetic layer, the exchange interaction between magnetic particles is reduced, and the fineness of the magnetic particles is reduced. Advances in elemental technologies such as media noise reduction due to computerization.

In the above-mentioned conventional so-called multi-particle magnetic medium, if the isolation and miniaturization of the magnetic particles of the medium are promoted to reduce noise, the recording density reaches the limit due to thermal disturbance. I know that.

Hereinafter, the thermal disturbance will be outlined. When the recording density is improved, the size of the recording cell formed on the medium is reduced, and the intensity of the signal magnetic field generated from the medium is reduced.
In order to satisfy the S / N ratio required by the system, noise must be reduced by the reduced signal amount. The medium noise is mainly caused by the fluctuation of the magnetization transition part,
The fluctuation amount of the magnetization transition portion is proportional to the size of the magnetization reversal unit of the magnetic particle. Therefore, in order to reduce the medium noise, the exchange interaction between the magnetic particles is cut off to isolate the magnetic particles (the fluctuation of the magnetization transition portion is reduced to the order of the size of one magnetic particle), and It is necessary to make the particles finer.

[0006] The magnetic energy of one isolated magnetic particle is given by the product of the magnetic anisotropic energy density of the particle and the volume of the particle. Reducing the thickness of the medium to reduce the width of the magnetization transition and reducing the size of the magnetic particles to meet the demand for low noise have resulted in a significant decrease in the volume of the magnetic particles, and the magnetic energy of the particles Is significantly reduced. If the magnetic energy of the particles is several hundred times the thermal energy at the operating temperature (at least room temperature) as a magnetic memory, the resistance to thermal disturbance is considered to be sufficient. However, when the magnetic energy of the particles is less than 100 times the thermal energy, the direction of magnetization of the magnetic particles changes due to thermal agitation, and the recorded information may be lost. This is the thermal disturbance problem, HD
This is the reason that the area density of D is said to reach its limit at about 40 to 50 Gb / in ² .

Several methods have been proposed to overcome the thermal disturbance problem.

One is to use a material having high magnetic anisotropy as the magnetic particle material. However, when the magnetic anisotropy is increased, the recording saturation magnetic field required by the medium increases, and it is necessary to further increase the saturation magnetic flux density of the recording head magnetic pole material. This cannot be a practical method as long as the available soft magnetic film material including the research level is considered.

Another one is photothermal assisted recording. In this method, a recording portion is heated by light irradiation at the time of recording using a material having a high magnetic anisotropy, and the anisotropy of magnetic particles and the recording saturation magnetic field are reduced to perform recording with an available recording head. . However, this method is not practical because it is necessary to provide a light irradiation system in an HDD having little extra space in a drive including between disks. Also,
This method involves an increase in power consumption and a corresponding increase in heat generation.

As another method for solving the thermal disturbance problem, S
Proximity optical recording using IL or evanescent light
It has been proposed as a technology seed for overcoming the recording density limit of DD. However, it is impossible for optical recording to achieve a high transfer rate comparable to magnetic recording unless a heat mode process is employed. Also, a method using a photon mode ultra-high-speed / ultra-high-density material has been proposed, but this method is still in the stage of exploratory research, and the technology is incomplete.

The above method cannot provide an appropriate solution to the problem of thermal agitation of the medium which physically hinders the high density of magnetic recording.

The most effective method for solving the thermal disturbance problem is considered to be a magnetic recording medium having magnetic particles regularly arranged in a non-magnetic matrix (hereinafter referred to as a regular magnetic medium). Particle media),
In addition, a magnetic recording medium having regularly arranged nonmagnetic particles (pores) in a continuous magnetic substance (hereinafter, referred to as a regular nonmagnetic pore medium) is used.

First, the regular magnetic particle medium will be described. Conventional multi-particle magnetic media such as CoCr have a structure in which mainly Cr-rich non-magnetic grain boundaries are precipitated between magnetic particles in order to reduce exchange coupling between magnetic particles. However, since the dispersion of the particle size and the distance between the particles is large, and the particles are irregularly arranged, even if the exchange interaction between the particles is separated and the particles are isolated, the medium noise is sufficiently low. Did not decrease and became a hindrance to the improvement of the recording density.

More specifically, when the variation in the particle size is expressed by the full width at half maximum (FWHM) of the distribution of the particle size, the variation is suppressed by about ± 50% with a typical medium and by devising such as low-speed sputtering. The medium also shows a value of ± 25% or more. For example, a medium having an average particle diameter of 20 nm typically has a large number of particles between 10 nm and 30 nm, and has a particle diameter of 1 nm.
This means that there is a considerable number of particles less than 0 nm and strongly affected by thermal disturbance.

The interparticle variation is more pronounced, typically ± 70% in FWHM and ± 45% in well-tuned examples.
% Or more. That is, a medium having an average distance between particles of 2 nm typically has a large number of particles having a distance between particles of 0.6 nm to 3.4 nm, and a considerable number of particles are connected and exchange-coupled. Means Further, the particle arrangement is random without any regularity.

As an example of a magnetic recording medium having regularly arranged magnetic particles, see, for example, Appl. Phys
s. 76 (10) 6673, 1994. In this method, a sample in which an Au plating seed layer and a resist are coated on a Si wafer is exposed by electron beam (EB) direct writing, and after development, Ni is plated and grown in a plurality of fine holes formed by EB direct writing. Diameter 35
The Ni pillar arrays are regularly formed at intervals of 100 nm.

Although the media described in the above documents have been studied with the application to magnetic recording media in mind,
It does not disclose specifically how to use it. This document merely suggests the possibility of realizing a recording density of 65 Gb / in ² simply because the medium has a pattern at intervals of 100 nm. In other words, in this document, one magnetic particle is regarded as a minimum recording unit, and one magnetic particle is present in the minimum recording cell. However, a magnetic recording and reproducing using such a small recording unit is performed. No description is given of devices such as a head and a servo system.

[0018] In addition to the examples described above, magnetic particles arranged regularly using the EB direct writing method were prepared. Vac. Sci.
Technol. B13 (6) 2850, 1995 and J.A. Vac. Sci. Technol. B12 (6)
3196, 1994. These are the EBs of regularly arranged magnetic particles.
Although the fabrication method other than the direct drawing process is slightly different,
One of them is the minimum recording unit. Also,
These documents do not describe magnetic particle size distribution, intergranular distribution, and the like.

However, although EB direct writing has no problem when used for preparing one sample at a laboratory level, it is not suitable from the viewpoint of cost and productivity when used in a process for manufacturing a magnetic medium industrially. It goes without saying that it is inappropriate.

Further, the method of using one magnetic particle as the minimum recording unit can be achieved by remarkably narrowing the track of the recording / reproducing head, improving the sensitivity of the reproducing head, improving the servo accuracy, etc.
Forcing a significant burden on elements other than the medium. Further, even if a high-resolution head is formed, since one particle constitutes one recording cell, medium noise is high and a sufficient S / N cannot be obtained.

In a conventional magnetic medium, an address pattern or a servo pattern is formed by magnetic recording by a manufacturer of a magnetic disk drive (servo writing). J.
Appl. Phys. 69 (8) 4724, 1991, it is proposed to implement an address pattern and a servo pattern by patterning a thin film. But,
The medium used in this document is not one in which magnetic particles are regularly arranged.

The method of manufacturing a magnetic medium is described in J.
pn. J. Appl. Phys. 30 (2) 282, 1
991, and J.I. Electrochem. So
c. 122 (1) 32, 1975, Porous Almai
A method in which a magnetic material is plated and grown in a substrate is disclosed.
In this method, the medium is preferably a Co-Cr group.
Gold is used to deposit a Cr-rich non-magnetic material at the grain boundaries
To reduce the exchange interaction between crystal grains and reduce noise
It is trying to make it. However, the matrix is Al_TwoO _ThreeLimited to
Co, Co-C which can be plated and grow magnetic material
r, Co-Ni, Fe-Cu, Fe-P, etc.
I have.

Next, a regular non-magnetic pore medium will be described. When recording is performed on a magnetic continuous film, medium noise is extremely large because the shape of the domain wall is greatly disturbed. Therefore, a magnetic continuous film is not used for magnetic recording, and a multi-particle magnetic medium is used instead. By arranging non-magnetic pores regularly in the magnetic continuous film, it is possible to prevent the shape of the domain wall from being disordered.

The above-mentioned thermal disturbance is caused by a decrease in the volume of the magnetic particles accompanying the increase in density. When the magnetic body itself is in a continuous form, such as a regular non-magnetic pore medium, the volume of the magnetic body may be regarded as infinite. Therefore, in a regular non-magnetic pore medium, there is no problem of thermal disturbance even if the non-magnetic pore is miniaturized to increase the density.

An example in which nonmagnetic pores are arranged in a continuous magnetic film is described in IEEE-Trans. Magn. 34 (4), 1
No. 609,1998, which is disclosed as a network medium. This document relates to a noise simulation of a virtual medium in which non-magnetic pores are regularly arranged in a multi-particle magnetic film. This document does not mention non-magnetic pore size, distribution of inter-pore distances, address patterns, and servo patterns at all.

[0026]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a magnetic recording medium capable of improving S / N and realizing high density and a method of manufacturing the same. With the goal.

[0027]

According to the present invention, a plurality of magnetic particles arranged in a continuous non-magnetic film are provided, and the magnetic particles contained in the smallest magnetic recording cell are arranged in the track length direction. The number of particles is at least four, the full width at half maximum of the distribution of the distance between the closest particles is ± 40% or less of the average distance between the nearest particles, and the full width at half maximum of the particle size distribution is There is provided a magnetic recording medium characterized by being ± 20% or less.

Further, according to the present invention, a plurality of non-magnetic pores arranged in a continuous magnetic film are provided, and a magnetic transition portion in the magnetic film is formed of a domain wall connecting the non-magnetic pores. A magnetic recording medium is provided, wherein the grain size is 0.5 to 3 times the average width of the domain wall.

In the present invention, the full width at half maximum of the distribution of the distance between the nearest pores in the smallest magnetic recording cell is preferably ± 40% or less of the average distance between the nearest pores.

According to the present invention, (a) a step of arranging a mask having openings arranged by self-organization on a continuous non-magnetic film; and (b) a step of irradiating an ion beam from above the mask to form a continuous non-magnetic film. A method for manufacturing a magnetic recording medium, comprising: forming a plurality of holes arranged in a magnetic film; and (c) forming a magnetic particle by filling the holes with a magnetic substance. Provided.

According to the present invention, (a) a step of disposing a photosensitive layer on a continuous magnetic film, and (b) a step of disposing a mask having openings arranged by self-organization on the photosensitive layer. (C) irradiating light or electrons from above the mask to expose the photosensitive layer, and then developing the photosensitive layer to form a mask pattern in which a portion corresponding to the opening remains. Manufacturing a magnetic recording medium, comprising: forming a plurality of magnetic particles arranged in a continuous magnetic film according to the mask pattern; and (e) filling a nonmagnetic material between the magnetic particles. A method is provided.

In the present invention, a plurality of magnetic particles arranged in the continuous non-magnetic film by the above-mentioned steps are provided, and the magnetic particles contained in the smallest magnetic recording cell are arranged in the track length direction. The number is at least four,
A magnetic recording medium in which the full width at half maximum of the distribution of the distance between the closest particles is ± 40% or less of the average distance between the nearest particles, and the full width at half maximum of the particle size distribution is ± 20% or less of the average particle size. It is preferred to manufacture.

Further, according to the present invention, (a) a step of arranging a mask having openings arranged by self-organization on a continuous magnetic film, and (b) irradiating an ion beam from above the mask to continuously Manufacturing a magnetic recording medium, comprising: forming a plurality of holes arranged in a magnetic film; and (c) forming a nonmagnetic pore by filling the holes with a nonmagnetic material. A method is provided.

According to the present invention, in each of the above steps, a plurality of non-magnetic pores arranged in a continuous continuous magnetic film are provided, and a magnetic transition portion in the magnetic film comprises a domain wall connecting the non-magnetic pores. It is preferable to manufacture a magnetic recording medium in which the average particle size of the pores is 0.5 to 3 times the average width of the domain wall.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a magnetic recording medium including a regular magnetic particle medium and a regular non-magnetic pore medium, and a method for producing the same.

Both the regular magnetic particle medium and the regular nonmagnetic pore medium have a form in which magnetic particles or nonmagnetic pores having a size of several tens nm or less are regularly arranged.

Hereinafter, the present invention will be described in detail with reference to the drawings. <Configuration of Magnetic Recording Medium According to the Present Invention> (A) Regular Magnetic Particle Medium FIG. 1 is a schematic view showing an example of a regular magnetic particle medium according to the present invention. FIG. FIG. 1B is a sectional view.

In the regular magnetic particle medium shown in FIG. 1, a seed layer 2 is formed on a substrate 1, and a magnetic recording layer 3 is formed on the seed layer 2. The magnetic recording layer 3
It comprises a plurality of magnetic particles 5 regularly arranged in a non-magnetic matrix 4. A protective layer 6 is formed on the magnetic recording layer 3. Here, "arranged regularly" means that the full width at half maximum of the distance distribution between the closest magnetic particles is ± 40% or less of the average distance between the closest magnetic particles.

The material for forming the substrate 1 is glass,
Examples thereof include materials similar to those used for ordinary magnetic media, such as Si or a material obtained by coating NiP on these materials.

The seed layer 2 is a layer for controlling the crystallinity of the magnetic layer 3, but need not be provided. Examples of the seed layer 2 include Cr, a Cr alloy, Cr, and NiFe.

The thickness of the seed layer 2 is preferably from 0 to 200
nm (0 nm is a form without the seed layer 2), more preferably 0 to 100 nm.

The meaning of the seed layer is mainly to control the crystallinity of the recording layer in the case of longitudinal recording, and the main component of the recording layer is Co.
In this case, a Cr-based or V-based alloy having a relatively small lattice constant mismatch with the hcp crystal of Co can be used as the seed layer. The seed layer grows in a cone shape or a column shape on the substrate surface. If the film thickness is too small, the crystallinity of the seed layer itself is insufficient and the effect as the seed layer is insufficient. The crystallinity of the seed layer in the thin film region also depends on the film formation method, and when ultra-high vacuum sputtering is applied, sufficiently good crystallinity is exhibited even at a film thickness of 50 nm or less, for example, 20 nm. Therefore, the lower limit of the thickness of the seed layer in the sense of controlling the crystallinity of the recording layer can be set to 20 nm or less. However, in the magnetic medium of the present invention, the matrix material can function as the seed layer. Therefore, a seed layer having no seed layer (0 nm) and a seed layer having a film thickness of 0 to 20 nm which has insufficient crystallinity but can be used to promote the effect of controlling the crystallinity of the magnetic particles by the matrix are also applicable to the present invention. Can be done. When an amorphous magnetic material such as RE-TM is used as the magnetic particle material, it is not necessary to select a seed layer for controlling crystallinity and a matrix material for controlling crystallinity. When there is no seed layer, the recording layer may be formed directly on the substrate, or may be formed on some underlying layer other than the seed layer. If the seed layer is too thick, the crystal grain size on the surface of the seed layer becomes excessively large, which impairs the miniaturization of the grain size of the recording layer formed thereon. Therefore, the upper limit of the thickness of the seed layer is preferably 200 nm, more preferably 100 n.
m, more preferably 50 nm.

The thickness of the magnetic recording layer 3 is preferably 5 to 5
0 nm, more preferably 10 to 25 nm. Since the lower limit of the film thickness is determined by the resistance to thermal disturbance, it depends on the magnetic material used. For example, in the case of a Co-Cr magnetic material, if the thickness is less than 10 nm, sufficient thermal disturbance resistance cannot be ensured, so the lower limit of the film thickness is 10 nm. Sm-C which shows sufficient thermal agitation resistance up to a film thickness of about 7 nm and has high anisotropy
In the case of an o-based magnetic material, sufficient thermal disturbance resistance is exhibited even at 5 nm. The upper limit is determined by the resolution. Since the index of the resolution is Mrt / Hc in the longitudinal medium, the thickness t of the recording layer can be increased when Hc is high. The upper limit of the recording layer thickness depends on the linear recording density (required value of resolution) and Hc.
nm, more preferably 25 nm.

As the non-magnetic matrix 4, C (carbon), Si--O, Si--N, Si--C, Ti--N, Ti
—C, Al—N, Ta—O, Ta—N, Al—O, IT
O, In-N, In-O, BN, Zr-N, Zr-
Oxides such as O and PTFE, nitrides, carbides, borides,
Wide selection from organics.

The material for forming the magnetic particles 5 should be selected from a wide range of materials such as Co-based alloys, rare earth / transition metal alloys (RE-TM) (RE: rare earth, TM: transition metal), and magnetic oxides. Is possible. As examples of Co-based alloys, Co-Cr, Co-Pt, Co-Fe, C
o-Cr-Ta, Co-Cr-Pt, Co-Cr-Pt
-Ta, Co, Fe, Tb-Fe, Tb-Co, Tb-
Fe-Co, Gd-Tb-Fe-Co, Gd-Dy-F
e-Co, Nd-Fe-Co, Nd-Tb-Fe-C
o, PtMnSb, Co ferrite, Ba ferrite and the like.

Among the above-mentioned magnetic particle materials, particularly preferred materials in the present invention are Co-Pt-based alloys, Co-T
b, Co, Co-Fe, a rare-earth / transition metal alloy, etc., a magnetic material with little segregation.

The magnetic recording medium of the present invention is preferably manufactured by a dry process using an ion beam or the like. Since it is a dry process, the selection range of the magnetic material and the matrix material is wide, and desired magnetic characteristics are easily obtained.

The protective layer 6 may be C or the like, but the protective layer 6 may not be provided.

The thickness of the protective layer 6 is preferably 0 to 20 nm.
(0 nm has no protective layer 6), more preferably 0 to 0 nm.
10 nm. The lower limit is defined by the protective function of the recording layer. In the case of a multi-particle random metal medium having a fine structure in which conventional magnetic particles are surrounded by grain boundaries, the magnetic particles themselves are mechanically
Since the chemical stability is insufficient, the coating of the protective film represented by the C type is essential, and a protective film of at least about 10 nm is required. In the present invention, the protective function of the magnetic particles can be assigned to the matrix material, so that the protective film may not be provided (0 nm). Further, it is more effective to provide a protective film in the range of 0 to 10 nm in order to promote the protective function of the matrix. The upper limit of the protective film thickness is defined by spacing loss. The thicker the protective film thickness, the more the sharpness of the recording magnetic field from the head is impaired, and the more the spatial steepness of the signal magnetic field generated from the medium is impaired. The upper limit of the protective film thickness depends on the linear density, the head structure, the flying height of the head, and the like, but is at most 20 nm, preferably 10 nm.

The crystal magnetic anisotropy and the magnetic properties of the magnetic layer 3 are adjusted by adjusting the crystallinity of the material of the seed layer 2, the thickness of the seed layer 2, the material of the magnetic layer 3, and the thickness of the magnetic layer 3. Can be adjusted.

For example, a relatively thick film of Cr is used for the seed layer 2 and a relatively thin film of Co—Pt, Co—F is used for the magnetic layer 3.
When e is used, the magnetic layer 3 shows in-plane magnetic anisotropy. Further, for example, when relatively thin Cr is used for the seed layer 2, the magnetic layer 3 exhibits three-dimensional random magnetic isotropy. Further, for example, NiFe
The magnetic layer 3 is made of Co-Pt, Co-
When Fe is used, the magnetic layer 3 exhibits magnetic anisotropy in a direction perpendicular to the film surface.

The crystal magnetic anisotropy and magnetic properties of the magnetic layer 3 can be adjusted by adjusting the conditions for forming the seed layer 2 and the magnetic layer 3. In the present invention, the anisotropy and magnetic properties after forming the regular magnetic particles 5 from the magnetic material are more important than the magnetic anisotropy of the continuous film made of the magnetic material.

The inventors simulated magnetic recording medium noise prior to embodying the present invention. As a result of the simulation, it has been found that when the magnetic particles 5 are regularly arranged, the medium noise is greatly reduced and the S / N is improved. Further, it has been found that the reduction effect is remarkable when the variation in the distance between the particles is 40% or less, and more remarkable when the variation in the particle size is 20% or less in FWHM.

In the regular magnetic particle medium of the present invention,
One magnetic particle 5 is not the minimum recording unit. That is,
The minimum recording cell 7 shown in FIG. 1 is not composed of one magnetic particle 5, but is composed of at least four magnetic particles 5 in the track length direction. Note that the minimum recording cell is a recording cell corresponding to the shortest cell length.

If the minimum recording cell 7 is composed of a plurality of magnetic particles 5 according to the present invention, the magnetic recording medium can be designed in accordance with the track width, gap length, servo accuracy, etc. of the head, and the medium noise can be sufficiently reduced. And the S / N can be improved. The number of magnetic particles 5 in the minimum recording cell 7 depends on the recording density and the aspect ratio of the recording cell.

In the present invention, since the nonmagnetic material 4 is basically used between the particles 5, it is not necessary to segregate Cr or the like.

(B) Regular non-magnetic pore medium FIG. 2 is a schematic view showing an example of a regular non-magnetic pore medium according to the present invention. FIG. 2 (a) is a plan view of a minimum recording cell.
FIG. 2B is a cross-sectional view. In the regular non-magnetic pore medium shown in FIG. 2, a seed layer 2 is formed on a substrate 1,
The magnetic recording layer 3 is formed on the seed layer 2. The magnetic recording layer 3 includes a plurality of non-magnetic pores 9 regularly arranged in the continuous magnetic film 8. A protective layer 6 is formed on the magnetic recording layer 3. Here, "arranged regularly" means that the full width at half maximum of the distribution of the distance between the closest nonmagnetic pores is ± 40% or less of the average distance between the closest nonmagnetic pores.

The material for forming the substrate 1, the seed layer 2, and the protective layer 6 is the same as the material for forming the substrate 1, the seed layer 2, and the protective layer 6 of the regular magnetic particle medium shown in FIG. Can be used.

The thickness of the magnetic recording layer 3 in FIG.
Is the same as the film thickness of the magnetic recording layer 3 of the regular magnetic particle medium. The magnetic material forming the continuous magnetic film 8 can be selected from the same magnetic particle materials as those in the regular magnetic particle medium, and can be selected widely from polycrystalline magnetic materials and amorphous magnetic materials. Particularly preferred materials are Co-Pt-based alloys, Co-Tb, Co, and Co-F, which are easy to form a continuous magnetic material and have few pinning sites on the domain wall.
e, a magnetic material such as a rare earth / transition metal alloy (RE-TM) (RE: rare earth, TM: transition metal).

Co-Tb is a material belonging to the RE-TM system and is a material for magneto-optical recording rather than for magnetic recording. However, since it is an amorphous continuous magnetic film, it is free of grain boundaries and has good workability. In addition, Co-Tb has a relatively large saturation magnetization (Ms) in the RE-TM system and can provide a high signal output, has a high Curie point, has excellent operating temperature characteristics, has good corrosion resistance, and has CSS resistance. It has advantages such as being easy.

The nonmagnetic material forming the nonmagnetic pore 9 can be selected from the same materials as those forming the nonmagnetic matrix 4 in the regular magnetic particle medium.

The non-magnetic pores 9 are connected by domain walls 10. The domain wall 10 is a part of the continuous magnetic film 8. For example, when the magnetizations of two adjacent recording cells have directions opposite to each other, the domain wall 10 located between the two cells has a magnetization in a direction intermediate between the two directions. Various types can be applied to the domain wall 10 according to the present invention depending on the type of the magnetic film 8, and there is no particular limitation. For example, the type of the domain wall 10 includes a Bloch domain wall or a Neel domain wall.

In the regular non-magnetic pore medium of the present invention, the regularly arranged non-magnetic pores 9 function as pinning sites of the domain wall 10, and the shape of the domain wall 10 follows the regularity of the pore 9. Therefore, although the magnetic film 8 is continuous, the noise is extremely low as a medium and the S / N is improved. In order for the pore 9 to effectively function as a pinning site of the domain wall 10, the pore size is preferably 0.5 or more of the width of the domain wall 10, and in order to obtain low noise characteristics, the pore size is three times the width of the domain wall 10. The following is preferred.

Normally, when a regular non-magnetic pore medium is formed, the continuous magnetic film portion 8 shows a magnetized state having the domain wall 10 immediately after the formation unless a method such as film formation in a magnetic field is performed. Generally, the pattern of the domain wall 10 appearing in the continuous magnetic film 8 immediately after the film formation is a random maze pattern. However, when the nonmagnetic pore diameter is between 0.5 and 3 times the domain wall width as in the present invention, the domain wall 10 is not in a maze shape, and the nonmagnetic pore 9 as shown in FIG. Here is a regular array that shows

Whether the domain wall 10 connects the nonmagnetic pores 9 depends on a comparison between the domain wall energy and the demagnetizing field energy. That is, when the domain wall energy is larger than the demagnetizing field energy, the domain wall 10 connects the nonmagnetic pores 9 because the nonmagnetic pores 9 are more stable in terms of energy. However, in the opposite case, the domain wall 10 is formed in a portion other than the non-magnetic pore 9 without connecting the non-magnetic pore 9, so that the domain wall 10 is more stable in energy. Is not concatenated.

The present inventors have found that it is preferable to select a magnetic material and a non-magnetic pore array so that the domain wall energy becomes higher than the demagnetizing field energy in order to reduce medium noise and improve S / N. I found it.

That is, the FWHM of the distribution of the distance between the closest pores of the non-magnetic pores constituting the minimum recording cell is adjusted to ± 40% or less of the average distance between the closest pores. It is preferable in terms of reducing

Table 1 below shows the recording density assuming the application of the present invention, and the magnetic particle diameter, magnetic particle spacing, pore diameter, and pore spacing required when the present invention is applied.

[0069]

[Table 1]

Table 1 shows that the aspect ratio of a recording cell is about 20 in a conventional magnetic medium, but that the aspect ratio will be reduced in the future, that is, narrower tracks will progress more rapidly than narrower bit pitches. Since the direction is predicted, the case where the aspect is 10 and the case where the aspect is 1 (proposed as a so-called square bit) are shown. Although the relationship between the bit density and the shortest cell length depends on the signal processing method, Table 1 uses the converted value when the 1/7 modulation method is adopted.

As described above, in the case of a regular magnetic particle medium, since the minimum recording cell is composed of at least four magnetic particles, the most preferable particle size for exhibiting low noise performance is the minimum recording cell length. It is 1/4 or less. Therefore, in Table 1, the particle size is set to 1/4 of the cell length.

The density of the magnetic particles was set to 50% or more in order to obtain a sufficiently large medium signal output, and the particle spacing was set to a particle size of +1 nm so that the exchange interaction between the particles could be completely separated. In Table 1, the number of magnetic particles contained in the minimum recording cell is represented by a value obtained by dividing the product of the track width and the shortest recording cell length by the particle interval.

In a regular non-magnetic pore medium,
Pore density is 50% for obtaining sufficiently large media signal output
It was set as follows. The pore spacing can be substantially used as long as it is equal to or less than the track width. However, in Table 1, the track width of 0.2 was set as a value having sufficient stability of the domain wall (magnetization transition) connecting the pores.

From Table 1, it can be seen that the ordered magnetic particle media of the present invention
It is clear that both regular non-magnetic pore media are useful as candidates for ultra-high density magnetic recording media.

<Method of Manufacturing Mask According to the Present Invention> The regular magnetic particle medium and the regular non-magnetic pore medium according to the present invention can both be manufactured using a mask having regularly arranged openings. . Therefore, a method of manufacturing a process mask having openings arranged regularly will be described first.

The mask for producing a plurality of magnetic particles regularly arranged from the magnetic layer or for producing a plurality of non-magnetic pores regularly arranged from the non-magnetic matrix layer is as follows.
For example, it can be manufactured using a self-assembly process.

The following is an example of the self-organizing process. (A) J.I. Electrochem. Soc. 100,
411, 1953, anodic oxidation of high purity Al. (B) A dispersion precipitation method of oxide microspheres. (C) Vapor deposition of oxide microspheres in gas. (D) Ge or Bi deposition on stearic acid as disclosed in Applied Physics Vol. 52, No. 8, 712, 1983. (E) Heteroepitaxial growth of Cu phthalocyanine on graphite. (F) Appl. Phys. Lett. 64 (2) 19
6, 1994, discloses InA on GaAs.
s dot formation. (G) Appl. Phys. Lett. 64 (4) 42
Au on complex organic materials disclosed in U.S. Pat.
Dot formation. In the present invention, any method of the above-described self-organization process can be applied, and another method that does not use the self-organization process is also applicable.

As an example of a method of manufacturing a mask by using a self-assembly process, a mask is formed by using the above-described (a) anodizing method of high-purity Al and (c) a vapor deposition method of oxide microspheres in gas. The method for manufacturing the will be described.

(A) Method of Manufacturing Mask by Anodic Oxidation of High-Purity Al
It comprises the steps of (1) forming porous alumite, and (2) forming a mask from porous alumite.

Hereinafter, each of the steps will be sequentially described. (1) Step of Forming Porous Alumite This step includes the following steps (a) to (c). (A) A 4N or 5N grade high purity Al plate is mirror-polished. (B) The mirror-polished Al plate is neutralized after chemical polishing with perchloric acid or alkali polishing in a sodium hydroxide solution. (C) After neutralization, the Al plate is immersed in an anodic oxidation solution of several% to several tens%, and a positive voltage is applied to the Al plate using Pt, C, etc. as a negative electrode, and anodized for a predetermined time. I do.

As the anodizing solution, an aqueous solution of oxalic acid, phosphoric acid, sulfuric acid, chromic acid or a mixed acid thereof is used. By anodization, a continuous Al ₂ O ₃ barrier layer is formed on the surface of the Al plate, and porous alumite (Al ₂ O ₃ ) is formed on the barrier layer. Porous alumite has a plurality of unperforated micropores regularly arranged. The formation of such a porous alumite is called self-organization.

FIG. 3 is a schematic sectional view showing a barrier layer formed by anodic oxidation and porous alumite. As shown in FIG. 3, anodized oxidized Al initial growth barrier layer 1
2 is formed thereon, and a porous alumite portion 14 of anodized Al having a plurality of micropores 13 is formed thereon. In FIG. 3, C indicates the unit cell size of porous alumite (corresponding to the micropore interval), P indicates the micropore size, and W indicates the thickness of the alumite wall surrounding the periphery of the micropore.

Such a self-organized porous alumite 1
The formation mechanism of No. 4 is that the anodizing solution contains Al and Al oxide (Al
₂ O ₃ ). That is,
When the raw material Al is immersed in an oxidizing solution and a voltage is applied, A
The anodized Al layer is formed while the surface is dissolved, and a part of the formed Al oxide is dissolved in the solution. Oxidation A after Al oxide is dissolved and flows out into the solution
On the 1 surface, the electric field is concentrated and the current density increases. When the current density increases, micropores 13 are formed because the dissolution of Al oxide is promoted. At the same time, around the micropores 13, dissolved excess Al or Al oxide is supplied,
The growth of Al oxide walls is promoted.

The partial dissolution of Al oxide as described above, that is, local dissolution, occurs selectively in Al itself or in a defect portion of natural Al oxide remaining on the Al surface.
As described above, after the local melting occurs, the micropores 13 are formed.
Is formed, and the wall of Al oxide grows, the electric field weakens.
When the electric field is weakened, a portion having a strong electric field is formed again next to the Al oxide wall to maintain the total electric field strength on the Al oxide surface, and the micro holes 13 are formed.

In the initial stage of the anodic oxidation, the formation of the fine holes 13 is started from the randomly distributed defect portions. However, as described above, since the periodic and regular electric field spatial distribution is generated around the formed minute holes 13, it is considered that the minute holes 13 form a regular array in a self-organizing manner.

As shown in FIG. 3, the Al plate 11 and the Al oxide
At the interface with the barrier layer 12, a concave surface is formed for each unit cell. When the member on which the porous alumite 14 is grown is immersed in a relatively high concentration phosphoric acid or chromic acid solution to remove the porous alumite 14, the Al plate 11 having regularly arranged concave surfaces is obtained. This A
When the above-described anodization is performed again on the l-plate 11, the projections located between the concave surfaces on the Al plate 11 play the role of the above-described defective portions, so that the regularity is better than that of the first anodization. Porous alumite 1 with self-organizing pattern
4 can be obtained.

The growth rate of the porous alumite 14 depends on the anodizing conditions, mainly the anodizing voltage, but is typically several to 100 nm / min. Further, the depth of the micropores 13 can be adjusted by the anodic oxidation time.

In the trial manufacture of the magnetic medium described later, the size of the micropores 13 formed as described above corresponds to the size of the magnetic particles or the size of the nonmagnetic pore, and the interval between the micropores 13 is the size of the magnetic particles or the nonmagnetic pore. Corresponding to Further, the depth of the minute holes 13 is related to the characteristics of the magnetic film processing.
The size of the micropores 13 and the spacing between the micropores 13 depend on the type of acid used for anodic oxidation, the anodic oxidation voltage, and the anodic oxidation bath temperature.

As described above, the pore spacing is C, the pore diameter is P,
Let W be the thickness of the Al oxide wall formed around the hole,
When the voltage applied to 1 is set to E, the following relationship is experimentally obtained. C = 2WE + P (1) The pore diameter P and the thickness W of the Al oxide wall are as follows:
Depends on concentration and bath temperature. The diameter of the micropores 13 can be adjusted by the type, concentration, and bath temperature of the acid.
The interval of 3 can be widely adjusted by the kind of acid, concentration, bath temperature, and applied voltage. The regularity of the arrangement of the micropores 13, that is, the pore size distribution and the pore spacing distribution, depend on the purity of Al, the amount of additives such as Mg in Al, the treatment method before anodizing, the anodizing rate, and the number of times of anodizing. Dependent.

(2) Step of Producing a Mask from Porous Alumite A method of forming a mask from the porous alumite 14 formed on Al is described in, for example, Jpn. J. Appl. Phys
s. 35-2 (1B) L126, 1996.

In this method, the following (a) to (e)
Step is included. (A) Micropores 13 of porous alumite 14 shown in FIG.
An organic resin mold such as a resist is formed on the surface including the. (B) The Al plate 11 is removed by etching. (C) The Al oxide barrier layer 12 is removed. (D) Fill the resin mold with a metal such as platinum. (E) Remove the resin mold. Through the series of steps described above, a metal mask such as platinum having a through hole is manufactured.

Further, Jpn. J. Appl. Phys.
31-2 (12B) L1775, 1992 and S
Science, 268, 1466, 1995 discloses a method in which a resist is buried in porous alumite to form a negative pattern, and then a replica of oxide, platinum (Pt) or the like is formed, and a mask is formed from the replica. I have.

Science, 268, 1466, 19
In the method disclosed in No. 95, in addition to oxide and platinum, SiC, SiO ₂ ,
A CVD growth material such as aC: H can be used. Therefore, the etching resistance and mechanical strength of the mask can be improved as compared with the case where the porous alumite itself is masked.

When a mask is manufactured from a replica as described above, the mask may be manufactured as it is from a porous alumite pattern, but a metal ring made of a metal such as Cu is prepared for mechanical holding, and a metal ring is prepared. After arranging the porous anodized honeycomb pattern in the opening of the ring, a mask may be formed from the porous anodized pattern. When manufactured using a metal ring, the mechanical strength and handleability of the manufactured mask can be significantly improved.

FIG. 4 is a schematic plan view and a schematic sectional view showing an example of a metal ring. Mask is metal ring 1
5 are formed in the openings 16. Fabrication of a mask using the metal ring 15 is described, for example, in Science, 268, 1
466, 95 can be performed by a modified method of the replica method.

(B) Method for Producing a Mask Using Vapor Deposition of Oxide Microspheres This method includes the following steps.

(A) An oxide such as TiO ₂ forming microspheres on the order of 10 nm is placed in, for example, a raw material boat of an electron beam evaporation apparatus, evacuated, and then irradiated with an electron beam to evaporate TiO ₂ . .

(B) The evaporating substance is guided from the passage hole of the partition wall provided in the vapor deposition chamber to another chamber having a high gas pressure. In this separate chamber, TiO ₂ microspheres on the order of 10 nm are formed in the gas phase due to the supercooling of the evaporant.

(C) The formed microspheres are charged by passing them through plasma or spraying an ozonizer on the microspheres, and then the charged microspheres are deposited on a mask substrate. The deposited microspheres are regularly arranged on the substrate while repelling each other by Coulomb force. As a result of the alignment, a regular self-assembled pattern of TiO ₂ spheres having a particle size of 10 nm is formed.

(D) A mask is manufactured from the formed pattern. The production of the mask is performed, for example, as follows. For example, a resist is buried in the formed pattern, and a negative pattern of the resist having regularly arranged concave portions is produced. By subjecting the negative pattern to a transfer process, a mask having the same pattern as the self-assembled pattern can be formed.

Next, a method for manufacturing a magnetic recording medium according to the present invention will be described. First, a method of manufacturing using the mask manufactured as described above will be described. next,
A method for manufacturing a magnetic recording medium without using a mask will be described.

<Method for Producing Magnetic Recording Medium According to the Present Invention Using Mask> Among the masks produced as described above, in particular, the regular magnetic particle medium according to the present invention is produced using a mask produced from porous alumite. And a method of manufacturing a regular non-magnetic pore medium will be described.

(A) Method for Producing Regular Magnetic Particle Medium First, a method for producing a regular magnetic particle medium having a normal pattern will be described. Next, a method for manufacturing a regular magnetic particle medium having a servo pattern will be described.

(A-1) Method for Producing Regular Magnetic Particle Medium with Regular Pattern The regular magnetic particle medium having the structure shown in FIG. 1 is formed on a substrate mounted in a film forming apparatus such as a multi-chamber magnetron sputtering apparatus. Then, the seed layer, the magnetic layer, and the protective layer are sequentially formed by sputtering to be manufactured.

The method basically includes two processes:
The first process and the second process can be applied. Both processes can be used to make the regular magnetic particle media shown in FIG. The first process requires a larger number of processes and a PEP process than the second process, but has the advantage that the self-assembled mask does not undergo any alteration during the process and can be used repeatedly and many times. There is.

FIG. 5 shows the flow of these processes.

(1) First Process (a) A magnetic layer is formed on a substrate. As described above, the seed layer and the protective layer may or may not be formed. (B) A resist is coated on the magnetic layer. (C) A substrate is placed immediately below the self-assembled mask produced as described above.

(D) Light irradiation or electron beam batch irradiation is performed from above the mask to expose the resist. After exposure, the resist is developed. If a positive resist is used, only the exposed portion remains as a pattern on the magnetic layer due to the development process. This resist pattern matches the honeycomb pattern at the opening of the self-assembled mask.

(E) The resist pattern is transferred to the magnetic layer by ion milling or RIE. In the ion milling method, batch milling is performed using an ion source having a larger diameter than a substrate on which a magnetic layer is formed (a disk substrate in the case of HDD application), or the substrate is rotated below a small-diameter ion source. Do it. The milling rates of the resist, the magnetic layer, the seed layer, and the protective layer are checked in advance. If the milling time is set with reference to the investigated rate, only the magnetic layer can be patterned into regular columnar magnetic particles before the resist is milled off. Since the seed layer remains under the magnetic particles, good magnetic properties are maintained. The seed layer between the magnetic particles may be milled.

(F) After patterning the magnetic layer, the resist residue is removed as necessary (using ashing, dipping, etc.).

The regular magnetic particle medium according to the present invention is manufactured by the above steps (a) to (f).

(G) To improve the mechanical strength and corrosion resistance of the medium, a matrix material is further embedded between the magnetic particles produced as described above.

The embedding can be performed by a film forming method such as CVD, sputtering, or vapor deposition. From the viewpoint of embedding the matrix material between the magnetic particles, an anisotropic film forming method such as collimation sputtering is preferable. However, since the embedding depth (a depth equivalent to the thickness of the magnetic particles) is as small as about 10 nm, Whatever technique is used, relatively good embedding can be performed.

(H) After the matrix is embedded, the surface of the medium has an uneven surface. Therefore, if necessary, the surface of the medium is subjected to a surface flattening process. The method of the surface flattening process includes, for example, waffle varnish, tape varnish, CMP, ion polishing, or a combination thereof.

For example, when CVD-C is used as a matrix, and tape burnishing and ion polishing are used for flattening the surface, Ra <1 nm can be realized as the surface roughness.

(I) After the planarization process, if the matrix material covers the top of the magnetic particles, it can be used as a regular magnetic particle medium as it is. When the matrix material does not cover the top of the magnetic particles but exposes the top of the magnetic particles, it is preferable to coat the surface of the medium with a protective film after the planarization process.

(J) Although not shown in FIG. 5, finally, a lubricating layer is coated on the surface of the medium in the same manner as a normal magnetic medium. Since the lubricating layer can be used instead of the protective film, when the magnetic particles are exposed as described above,
A lubricating layer may be coated on the surface of the medium.

(2) Second Process (a) A matrix material is formed on a substrate as a continuous film. As described above, the seed layer and the protective layer may or may not be formed. (B) The substrate is placed immediately below the self-assembly mask. (C) By ion milling or RIE,
The matrix material is patterned according to the self-assembled mask. The patterning forms a plurality of regularly arranged holes in the matrix material.

(D) The magnetic particle material is embedded in the holes formed in the matrix material. It is preferable to apply an anisotropic film forming method such as collimation sputtering in order to maintain good magnetic properties near the side wall of the hole. However, since the buried thickness is about 50 nm at most, a normal isotropic film forming method is used. However, the deterioration of the magnetic characteristics is insignificant, and there is no problem in practical use.

(E) After embedding the magnetic particles, the surface is flattened by a method similar to the first process such as burnishing, CMP, or ion polishing.

In the first process, a magnetic material is disposed on the lower side and a matrix material which is usually harder than the magnetic material is disposed on the upper side. Therefore, it is necessary to strictly control the end point of the flattening process. In (B), since a hard matrix material is disposed on the lower side and a magnetic material is disposed on the upper side, the management of the end point is relatively easy in any planarization process. The process after the planarization can be performed according to the first process.

In both the first process and the second process described above, the adjustment of the magnetic characteristics of the medium can also be performed by adjusting the temperature at which the magnetic material is formed, performing annealing after the formation of the magnetic particles, and the like. .

In both the first process and the second process described above, a plurality of magnetic particles regularly arranged in a continuous non-magnetic film according to the present invention are provided and included in the smallest magnetic recording cell. The number of particles arranged in the track length direction is at least four, and the full width at half maximum of the distribution of the distance between the closest particles is ± 40% or less of the average distance between the closest particles, It is possible to manufacture a magnetic recording medium in which the full width at half maximum of the particle size distribution is ± 20% or less of the average particle size.

(A-2) Method of Manufacturing Regular Magnetic Particle Medium Having Servo Pattern Next, a method of manufacturing a regular magnetic particle medium having a servo pattern will be described. 6A and 6B are schematic diagrams showing an example of a servo pattern of a magnetic disk. FIG. 6A shows an example of an arrangement, and FIG. 6B shows a form of a servo pattern. When the present invention is applied to a magnetic medium having a servo pattern, the following three embodiments can be considered. That is, (i) a mode in which a magnetic particle portion is formed after a servo pattern is formed;
(Ii) a mode in which a servo pattern and a magnetic particle portion are formed simultaneously; and (iii) a mode in which a servo pattern is formed after forming a magnetic particle portion.

Hereinafter, each embodiment will be described. (I) An embodiment in which a magnetic particle portion is formed after a servo pattern is formed is described in, for example, p. 75, the following series of steps can be applied.

(A) Forming a servo pattern with a resist on the substrate (b) Transferring the pattern to the substrate surface using the resist as a mask (c) Embedding a magnetic film for servo in the substrate (d) Lifting off the resist ( e) Flattening the surface After the embedded servo is formed, a regular magnetic particle medium may be formed as described above.

(Ii) A mode in which a servo pattern and regular magnetic particle portions are simultaneously formed can be performed by providing a servo pattern in a part of a self-organizing mask in advance.

Specifically, in a transfer process for forming a mask from porous alumite, for example, a part of the resist negative may be exposed and developed according to a servo pattern.

(Iii) In a mode in which a servo pattern is formed after a regular magnetic particle portion is formed, a resist is patterned on regularly arranged magnetic particles, and a data portion including a plurality of magnetic particles is stored as it is. Then, only the servo portion may be etched as necessary, and the servo magnetic film may be embedded.

(B) Method for Manufacturing Regular Nonmagnetic Pore Medium First, a method for manufacturing a regular nonmagnetic pore medium having a normal pattern will be described. Next, a method of manufacturing a regular non-magnetic pore medium having a servo pattern will be described.

(B-1) Method for Producing Regular Non-Magnetic Pore Medium with Regular Pattern The regular non-magnetic pore medium shown in FIG. 2 can be used, for example, in the method for producing a regular magnetic particle medium shown in FIG. It can be performed according to it. That is, in the process flow of the regular magnetic particle medium shown in FIG. 5, the magnetic layer and the matrix layer, and the magnetic particles and the matrix may be reversed. Also in this method, the first process and the second process as shown in FIG. 5 can be applied.

(1) First Process (a) A non-magnetic matrix layer is formed on a substrate. The seed layer and the protective layer may or may not be formed. (B) A resist is coated on the non-magnetic matrix layer. (C) A substrate is placed immediately below the self-assembled mask produced as described above.

(D) Light irradiation or electron beam batch irradiation is performed from above the mask to expose the resist. After exposure, the resist is developed. If a positive resist is used, only the exposed portion remains as a pattern on the magnetic layer due to the development process. The pattern of the resist coincides with the honeycomb pattern at the opening of the self-assembled mask.

(E) The resist pattern is transferred to a non-magnetic matrix by ion milling or RIE. In the ion milling method, batch milling is performed using an ion source having a larger diameter than a substrate on which a matrix layer is formed (a disk substrate in the case of HDD application), or the substrate is rotated below a small-diameter ion source. Do it. The milling rates of the resist, the nonmagnetic layer, the seed layer, and the protective layer are checked in advance. If the milling time is set with reference to the investigated rate, only the matrix layer can be patterned into regular columnar non-magnetic particles before the resist is milled off. The seed layer remains below the non-magnetic particles. The seed layer between the non-magnetic particles may be milled.

(F) After patterning the non-magnetic layer in this manner, the resist residue is removed (using ashing, dipping, etc.) as necessary.

(G) A magnetic material is embedded between the non-magnetic particles. The embedding can be performed by a film forming method such as CVD, sputtering, or vapor deposition. From the viewpoint of embedding the magnetic material between the non-magnetic particles, an anisotropic film forming method such as collimation sputtering is preferable, but the embedding depth (a depth equivalent to the thickness of the non-magnetic particles) is very small at about 10 nm. Since it is small, relatively good embedding can be performed using any method.

(H) After the magnetic material is embedded, the surface of the medium has an uneven surface. Therefore, the surface of the medium is subjected to a surface flattening process as necessary. Examples of the method of the surface flattening process include waffle varnish, tape varnish, CMP, ion polishing, or a combination thereof.

(I) After the planarization process, the surface of the medium is coated with a protective film. (J) Although not shown in FIG. 5, finally, a lubricating layer such as a lube is coated on the surface of the medium as in a normal magnetic medium. A lubricating layer may be coated on the surface of the medium instead of the protective film.

(2) Second Process (a) A material to be a magnetic layer is formed as a continuous film on a substrate. As described above, the seed layer and the protective layer may or may not be formed. (B) The substrate is placed immediately below the self-assembly mask. (C) By ion milling or RIE,
The magnetic material is patterned according to the self-assembled mask. By patterning, a plurality of holes regularly arranged in the magnetic material are formed.

(D) Non-magnetic particle material is embedded in the holes formed in the magnetic material. It is preferable to apply an anisotropic film forming method such as collimation sputtering for embedding, but since the embedding thickness is about 50 nm at most, there is no practical problem even if ordinary isotropic film forming is used.

(E) After the non-magnetic particles are embedded, the surface is flattened by a method similar to the first process such as burnishing, CMP, or ion polishing.

In the second process, a soft magnetic material is disposed on the lower side, and a non-magnetic matrix material, which is usually harder than the magnetic material, is disposed on the upper side. In the first process, a non-magnetic matrix material is disposed on the lower side, and a magnetic material is disposed on the upper side.
Endpoint management is relatively straightforward in any planarization process. The process after the planarization can be performed according to the first process.

In both the first process and the second process described above, a plurality of non-magnetic pores according to the present invention, which are regularly arranged in the diamagnetic film, are provided, and the magnetization transition portion in the magnetic film is non-magnetic. A magnetic recording medium comprising domain walls connecting magnetic pores, wherein the average particle size of the non-magnetic pores is 0.5 to 3 times the average width of the domain walls, and in addition to these characteristics, the closest pore in the smallest magnetic recording cell It is possible to manufacture a magnetic recording medium in which the full width at half maximum of the distribution of distances between them is ± 40% or less of the average distance between the nearest pores.

In both the first process and the second process described above, the adjustment of the magnetic properties of the medium can also be performed by adjusting the temperature at which the magnetic material is formed, performing annealing after the formation of the magnetic particles, and the like. It is.

(B-2) Production of Regular Non-Magnetic Pore Medium Having Servo Pattern Next, a method for producing a regular non-magnetic pore medium having a servo pattern will be described. As the servo pattern, for example, the pattern shown in FIG. 6 can be used as in the case of the regular magnetic particle medium.

When the present invention is applied to a medium having a servo pattern, the following three embodiments can be considered. That is, (i) a mode in which a non-magnetic pore portion is formed after a servo pattern is formed, (ii) a mode in which a servo pattern and a non-magnetic pore portion are formed simultaneously, and (iii) a mode in which a non-magnetic pore portion is formed. A servo pattern is formed.

Hereinafter, each embodiment will be described. (I) An embodiment in which a non-magnetic pore portion is formed after a servo pattern is formed is described in, for example, p. 75, the following series of steps can be applied.

(A) Forming a servo pattern with a resist on the substrate (b) Transferring the pattern to the substrate surface using the resist as a mask (c) Embedding a magnetic film for servo in the substrate (d) Lifting off the resist ( e) Planarizing the surface After forming the embedded servo, a regular non-magnetic pore medium may be formed as described above.

(Ii) The simultaneous formation of the servo pattern and the non-magnetic pore portion can be performed by providing a servo pattern on a part of the self-organizing mask in advance.

Specifically, for example, in a transfer process of forming a mask from porous alumite, a part of the negative resist may be exposed and developed according to a servo pattern.

(Iii) In a mode in which a servo pattern is formed after a non-magnetic pore portion is formed, a resist is patterned on regularly arranged pores, and a data portion including a plurality of non-magnetic pores is held as it is. Then, only the servo portion may be etched as necessary, and the servo magnetic film may be embedded.

<Method for Manufacturing a Magnetic Recording Medium According to the Present Invention Without Using a Mask> Next, a method for manufacturing a magnetic recording medium according to the present invention without using a mask such as the above-described self-organizing mask will be described. explain. As an example, a method for producing a regular magnetic particle medium according to the present invention without using a mask will be described.

FIG. 7 is a schematic view showing an example of an apparatus for producing a regular magnetic particle medium without using a mask.

The apparatus shown in FIG. 7 is provided with a vacuum vessel 20 for connecting a gas introduction system to an exhaust system.

On the floor of the vacuum vessel 20, an induction heating type evaporation source 21 is arranged. The evaporation source 21 includes a heater 22
Consists of a crucible 23 wound around and a shutter 24 disposed above the crucible 23. The heater 22 is connected to an RF power supply 25 arranged outside the container 20. An evaporating sample 26 for evaporating is placed in the crucible 23.
Is filled.

The ceiling portion of the vacuum vessel 20 has a superconductor section 2
7 are arranged. The superconductor portion 27 includes a cold head 28 suspended from the ceiling, a superconductor 29 mounted on the lower surface of the cold head 28, a magnetic disk substrate 30 mounted on the lower surface of the superconductor 29, It is composed of a magnetic field application coil 31 arranged on the side. The coil 31 is also hung from the ceiling.

Using the apparatus shown in FIG. 7, the following procedure is performed.
Regular magnetic particle media can be manufactured. (A) After evacuating the contents of the vacuum vessel 20 to 10-4 Pa or less, the cold head 28 is operated to cool the superconductor 29 to a temperature at which the superconductive state is developed. (B) Energizing the magnetic field applying coil 31 to cause the superconductor 29
A magnetic field in a direction perpendicular to is applied.

When a magnetic field is applied to the superconductor 29 in the superconducting state, eddy currents in a triangular lattice form regularly arranged inside the superconductor 29 flow. A magnetic field 32 perpendicular to the surface of the superconductor 29 is generated from the center of each eddy current, and no magnetic field 32 is generated in areas other than the center of the eddy current. That is, on the surface of the superconductor 29, a pattern of the magnetic field 32 having a magnetic flux perpendicular to the surface regularly arranged in a triangular lattice is formed.

The interval between the patterns of the magnetic field 32 is
9 types depending on the applied magnetic field strength. For example, when YBCO, which is an oxide high-temperature superconductor, is used as the superconductor 29 and the applied magnetic field is 1 T, the pattern interval of the magnetic field 32 is less than 50 nm, which is a preferable value for implementing the present invention. . Since the interval between the patterns of the magnetic field 32 is inversely proportional to the square root of the applied magnetic field intensity, the pattern interval can be narrowed by increasing the magnetic field intensity. For example, when YBCO is used as the superconductor 29, the pattern interval of the magnetic field 32 is 25 to 50 nm.

(C) Magnetic fine particles (not shown) are deposited on the pattern of the magnetic field 32 formed in a self-organizing manner on the surface of the superconductor 29. For the deposition of the magnetic fine particles, an in-gas deposition method or the like can be applied. For example, a magnetic substance such as CoPt is mixed as a raw material in the evaporation sample 26, and the magnetic substance is evaporated by induction heating. Specifically, when the RF power supply 25 is operated and the induction heating coil 22 is energized with the shutter 24 closed, the magnetic material is heated and evaporated.

(D) Inert gas in vacuum vessel 20
About 0 to several hundred Pa are introduced. By the introduction, the evaporated magnetic material becomes supercooled in the gas phase, and for example, the diameter sub-n
A magnetic cluster of about m to several tens nm is formed.

(E) With the magnetic clusters formed, the shutter 24 is opened to guide the clusters onto the substrate 30 on which a regular magnetic field pattern is formed.

Since the magnetic cluster has almost no kinetic energy, the substrate 3 is randomly arranged up to the vicinity of the substrate 30.
Although it flies toward zero, it is regularly arranged on the substrate in the vicinity of the substrate 30 according to the pattern of the magnetic field 32 that is regularly arranged. Thus, regular magnetic particles can be produced on the substrate 30. (F) The formation process of the medium after obtaining the regular magnetic particles can be performed in the same manner as the above-described formation process of the regular magnetic particle medium. The characteristics of the regular magnetic particle medium obtained by such a method are the same as the characteristics of the regular magnetic particle medium formed by using the self-compositioning mask.

As described in detail above, according to the present invention, it is possible to greatly improve the recording density without particularly burdening elemental technologies other than a magnetic recording medium such as a head, a servo, and a signal processing device. .

Since the medium according to the present invention can be easily combined with another method for increasing the recording density, some examples of the combination will be described.

<Example of Combination of the Present Invention and Other Techniques> The combination of the medium according to the present invention and the perpendicular recording method has already been described in this specification. If the medium of the present invention is used in combination with a single-pole head suitable for perpendicular recording, there is a possibility that the recording density can be further increased.

The combination of the medium according to the present invention and the thermally assisted recording method is also easy. The heat-assisted recording method uses a medium having extremely large magnetic anisotropy at room temperature, improves the resistance to thermal agitation, and enables further finer particles. However, using a recording medium with high magnetic anisotropy requires a large magnetic field to perform magnetic recording.
The burden on the head becomes too large and is not practical. Therefore, in the heat-assisted recording method, only the portion to be recorded is heated using a laser beam or the like, and the anisotropy, that is, the recording magnetic field is reduced only at the moment of recording. If such a method is applied, the particle size can be further reduced even in a multi-particle random medium, so that the density can be increased. Also in the regular magnetic particle medium of the present invention, it is possible to employ a magnetic particle material having high magnetic anisotropy and to perform photothermal assist during magnetic recording. Therefore, by combining the medium according to the present invention and the heat-assisted recording method, a remarkably high recording density can be expected.

In addition to the above, IEEE-Trans. Ma
gn. 34 (4) 1552 and 1555, 1998, a medium using a keeper layer, a combination with a perpendicular medium which attempts to reduce burst noise by using a semi-hard magnetic undercoat instead of a soft magnetic undercoat, etc. Combinations with other technologies are possible without departing from the spirit of the present invention.

[0169]

EXAMPLES <Formation of Porous Alumite> (Example 1) Porous alumite was produced in accordance with the above-described mask manufacturing method by anodic oxidation of high-purity Al. Table 2 below shows the anodizing conditions, and the measurement results of the pore diameter P of the produced porous alumite and the thickness W of the Al oxide wall.

[0170]

[Table 2]

P and W are values obtained by averaging the values of P and W measured for each pore from the processed image after performing SEM observation on the surface of the porous alumite shown in FIG. 3 and performing image processing. The anodic oxidation rate was adjusted to 10 ± 1 nm / min by adjusting the applied voltage.

From Table 2 above, it can be seen that pores having a diameter of several
It can be seen that a wall having a thickness of sub nm to 1 nm has been formed per unit applied voltage.

Next, an experiment was carried out to change the pore size distribution and the pore interval distribution of the micropores by changing the purity of Al, the treatment method before anodic oxidation, and the number of times of anodic oxidation. Table 3 below shows the experimental results.

[0174]

[Table 3]

The FWHM (Pσ) of the pore size distribution and the FWHM (Cσ) of the pore spacing distribution were derived by image processing an SEM observation image of the produced porous alumite. Here, Pσ and Cσ are dispersion amounts with respect to the average pore diameter and average pore interval shown in Table 2, for example, Pσ: 20% is ±
It corresponds to 10%. The processing conditions before anodic oxidation were changed by changing the chemical polishing conditions for buff-polished high-purity Al. Anodizing rate is 10 ± 1n by adjusting applied voltage.
m / min.

In the above table, the sample of b8 having the smallest dispersion of the hole diameter and the hole interval is one in which defective portions as igniters of holes are regularly arranged in advance.

The arrangement of defects was performed as follows. First, a SiC substrate having a flat and smooth surface was set in an EB drawing apparatus. Then, the electron beam was raster-scanned on the surface of the SiC substrate to form a plurality of sub-nm-high protrusions arranged in a lattice on the SiC surface. Next, the SiC substrate on which the projections were formed was taken out of the EB lithography apparatus, and the SiC substrate was pressed against a high-purity Al plate to form a plurality of concave portions arranged in a lattice on the Al surface. Next, the Al plate on which the concave portions were formed was subjected to anodizing treatment under the conditions shown in Table 3.

In the sample of b8, the concave portion on the SiC substrate formed according to the EB drawing pattern before the anodizing treatment acts as an igniter for the hole of the Al plate.
Therefore, the arrangement of the holes follows the EB drawing pattern, and both the hole diameter and the hole interval are extremely small.

By combining the conditions of Tables 2 and 3 and controlling the anodic oxidation voltage, the average pore size was 8 to 40 nm, and the FWH of the pore size distribution was
M: 8 to 120% (120% means ± 60%),
Average pore spacing: 12 to 60 nm, pore spacing distribution FWHM: 1
Porous alumite was prepared in the range of 5-200%.

Even when the anodic oxidation rate was changed in the range of several to about 30 nm / min, P.sigma. And C.sigma. When the anodic oxidation rate is 30 nm / min or more, for samples other than the sample of b8 in Table 2, when the oxidation rate is increased by 10 nm / min, Pσ and Cσ are almost 5
% Increased. Regarding the sample b8, even when the growth rate was increased to 30 nm / min or more, the increase in Pσ and Cσ was not particularly observed.

<Formation of Mask Using Metal Ring> (Embodiment 2) The aforementioned Science, 268, 146
A mask was formed using a metal ring by using a method modified from the replica method disclosed in US Pat.

First, a Cu ring was prepared. Next, the resist on which the porous alumite pattern was copied
It was arranged at the opening of the u-ring. Next, Pt was continuously grown on the Cu ring, and Pt was grown in the opening of the ring according to the resist pattern. Thus, a replica made of Pt having a honeycomb-shaped pattern of porous alumite was formed. A mask was formed from the formed replica.

The opening shape of the mask formed as described above matched the pattern of the porous alumite with an error within 1 nm.

FIG. 8 shows an SEM image of the prototype mask viewed from above. In FIG. 8, a black circle corresponds to a through-hole portion, and white corresponds to a Pt wall portion. The mask shown in FIG. 8 has an average pore size of 20 nm, an average pore interval of 30 nm, and a pore size distribution FWH.
M is adjusted to 30%, and the hole interval distribution FWHM is adjusted to 40%.

The depth of the holes can be adjusted by the Pt growth time during replica formation other than the thickness of the porous alumite before transfer. In this example, the depth was set to 500 nm in consideration of applicability to a magnetic medium process. Depending on the area of the opening of the metal ring, if the inner diameter of the metal ring is several centimeters, the thickness of Pt may be 50 due to the effect of mechanical holding by the metal ring.
Even if the thickness is as thin as about 0 nm, destruction can be prevented if care is taken in handling the replica.

<Preparation of Regular Magnetic Particle Medium> (Example 3) A regular magnetic particle medium according to the present invention was prepared using the mask prepared in Example 2 in accordance with the method for producing a regular magnetic particle medium described above. did.

The thickness of the protective film on the magnetic particles was set to 10 nm, which is the same as that used for the conventional medium, for comparison with the conventional medium. The protective film material was a matrix material or a C film in the first process, and a C film in the second process. In addition, a fluorocarbon-based lubrication layer was formed on the outermost surface of all samples.
３3 nm was applied.

FIG. 9 is an SEM observation image of the regular magnetic particle medium actually manufactured from the top. In FIG. 9, white portions correspond to the non-magnetic matrix 4 and black circles correspond to the magnetic particles 5.

Using various self-assembled masks produced in Example 2, the average particle size was 7 to 42 nm, and the particle size distribution was FW.
HM: 8 to 150% (150% means ± 75%), average grain spacing: 12 to 60 nm, grain spacing distribution FWH
M: A regular magnetic particle medium was prepared in the range of 15 to 250%.

<Evaluation of Regular Magnetic Particle Medium> The regular magnetic particle medium produced in Example 3 was evaluated as follows. Using the VSM, the direction of the easy axis, the product of the remanent magnetization (Mr) and the thickness (t) of the magnetic particle in the easy axis direction, and the coercive force (H
c) The coercivity squareness ratio (S ^* ) was determined. The activation magnetic moment was obtained by fluctuation field measurement. The activation size (Da) of the magnetic particles was determined from the measured values of the magnetic particle volume ratio and the saturation magnetization. Da responds to the minimum reversal size of magnetic particles, which is consistent with the size of one physical particle if there is no exchange interaction between the particles.

From the TEM and SEM observations and the image processing of the observed images, the average particle diameter (D) of the magnetic particles, the average distance between the magnetic particles (C), the FWHM (Dσ) of the particle size distribution, the The FWHM (Cσ) of the distance distribution was determined.

The average particle diameter (D) of the magnetic particles corresponds to the average pore diameter P of the self-assembled mask, but D and P showed slightly different values due to the process of transferring from the mask. FWHM (Dσ) of the particle size distribution corresponds to the pore diameter dispersion Pσ of the self-assembled mask, but Dσ showed a slightly larger value because the dispersion in the transfer process was superimposed on Pσ. The average distance (C) between the magnetic particles is indicated by the same symbol C because there was no significant difference from the average distance (C) between the holes of the self-assembled mask as a result of observation. The distribution of the distance between the particles (C'σ) and the variance of the hole spacing of the self-assembled mask (Cσ) do not completely coincide with each other, reflecting the difference between the particle size variance Dσ and the pore size variance Pσ, and show a slight difference. Was.

The target area on the medium for which the above average value and distribution were examined is 2 μm square, which is a range sufficiently larger than the minimum recording cell size to which the present invention is applied. Therefore,
If the distribution within the 2 μm square of the target area is, for example, 20% or less, the distribution in the smallest recording cell is naturally 20%.
It is as follows.

As a final evaluation, a disk-shaped medium sample was set on a spin stand,
Using an MR head, recording / reproducing characteristics centered on medium noise characteristics were examined. The evaluation results are described below in order.

(Example 4) FIG. 10 is a diagram showing a result of measuring a relationship between an average distance (C) between magnetic particles and a product (Mrt) of a residual magnetization and a film thickness.

For the sample (longitudinal recording medium) having an in-plane easy axis of magnetization, Mrt was determined by a major loop measurement in the in-plane direction. For samples having an easy axis of magnetization in the vertical direction, Mrt was determined by a vertical major loop measurement. Also,
FIG. 10 shows that among the plurality of samples, the average particle diameter D is 9 to 11;
This is the result of selecting and examining a regular magnetic particle medium having a nm, a particle size dispersion Dσ of 30% (± 15%) or less, and an intergranular dispersion Cσ of 60% (± 30%) or less. The measurement was performed on a medium having a magnetic particle thickness of 10 nm.

In FIG. 10, A indicates that the magnetic particle material is Co.
B is the measurement result of the medium of the present invention in which the magnetic particles are Co-Pt, and C is the measurement result of the conventional medium for comparison. Conventional medium C is composed of Cr (100 nm) / CoCrTaPt (10 n
m) / C (10 nm) / multiparticulate random arrangement formed with a lubricant (3 nm). As the conventional medium, two samples having different magnetic particle diameters by changing the temperature at which the magnetic layer was formed by sputtering were prepared.

When the film thickness and the particle size are constant, the magnetic material is particularly inferior.
If not, Mrt is C ^-2Is proportional to Figure 1
In the measurement results of A and B of 0, Mr.
t is C^-2Is proportional to However, the measurement result of the conventional medium
In, is not as the theory.

Further, the value of Mrt for the same C is determined by the amount of the magnetic element in the magnetic particles. Co-Pt of the present invention
And the conventional CoCrTaPt medium, although the magnetic element concentration is almost the same,
t is lower than that of the medium of the present invention. The result is
In the conventional medium, there is a particle that is superparamagnetic due to thermal disturbance due to a wide particle size distribution, and the Mrt is reduced. However, in the regular magnetic particle medium of the present invention, the particle dispersion is small, so that the medium becomes superparamagnetic. This indicates that few particles are present.

Mrt is an amount related to the signal output and the magnetization transition width in terms of magnetic recording characteristics. The signal output is larger as the Mrt is larger. However, when the coercive force is the same, the magnetization transition width is wider as the Mrt is larger. High density recording becomes difficult. Therefore, Mrt is an amount that should be appropriately adjusted according to other magnetic characteristics, noise characteristics, and characteristics of a recording / reproducing system such as a head. As shown in this example, it is understood that Mrt can be appropriately adjusted by adjusting the average distance C between the magnetic particles in the medium of the present invention.

(Example 5) FIG. 11 is a view showing the result of measuring the relationship between the average particle diameter D of magnetic particles and the coercive force Hc. Hc is a measured value of each sample in the easy axis direction. FIG. 11B shows the measurement results of the medium of the present invention using Co—Pt magnetic particles, and C shows the measurement results of the conventional medium used in Example 4. The measurement result of B is the particle size distribution Dσ
Is 30% (± 15%) or less, the average value of the distance between particles is an average particle diameter D + (1-2 nm), and the dispersion of the distance between particles is 60%.
(± 30%) It is a measurement result about the regular magnetic particle medium of the present invention which is below.

The measurement of the coercive force Hc was performed by measuring the VSM major loop at room temperature for 10 minutes or more.
The smaller the particle size of the magnetic particles, the higher the Hc
Will be lower. The effect of thermal disturbance can be estimated from the magnetic anisotropy and particle volume of the particles.

[0203] The solid line in FIG.
It is a theoretical curve of Hc of Pt magnetic particles, which is fitted with Hc when the particle diameter of the magnetic particles is assumed to be sufficiently large. The broken line in FIG. 11 is a theoretical curve of Hc of CoCrTaPt magnetic particles of the conventional medium.
When comparing the curve of the measurement result and the theoretical curve, both curves are consistent in the medium of the present invention having a small particle size dispersion,
In the case of the conventional medium having a large dispersion, the measurement result is lower than the theoretical curve. It is considered that the reason for the decrease is that the conventional medium contains superparamagnetic particles, as in the description of the measurement result of Mrt in Example 3.

Hc is an amount related to the magnetic transition width and the recording sensitivity in the magnetic recording characteristics. If Mrt is the same, H
The larger c is, the narrower the magnetization transition width becomes, which is suitable for high density recording. However, when the coercive force squareness ratio S ^* is the same, the recording sensitivity decreases as Hc increases. Therefore, Hc is also an amount that should be appropriately adjusted according to the recording / reproducing system. As shown in this example, in the medium of the present invention, Hc can be appropriately adjusted by adjusting the average particle size of the magnetic particles.

(Example 6) FIG. 12 is a graph showing the relationship between the dispersion Cσ ′ of the distance between particles (shown as Ｈ of FWHM), the activated size Da of the magnetic particles, and the average particle size D of the magnetic particles. It is a figure which shows the result of having measured the relationship between Da / D which is a ratio.

In FIG. 12, A indicates that the magnetic particle material is Co.
B is the measurement result of the medium of the present invention in which the magnetic particles are Co-Pt, and C is the measurement result of the conventional medium used in Example 4. The measurement of the medium of the present invention shows that the particle size dispersion Dσ is FWHM
The measurement was performed on a medium sample adjusted within 30%.

The measurement results of the medium of the present invention show that Da / D is 1 in a medium in which the dispersion of the distance between particles is adjusted to ± 40% (FWHM: 80%) or less. Da is the minimum magnetization reversal unit, and coincides with the physical grain system D when the exchange interaction between magnetic particles is separated. The reason why Da / D increases with dispersion in a region where the dispersion is 80% or more can be interpreted as follows. That is, when the dispersion of inter-particle distances C′σ is large due to a low degree of completeness of the self-assembled mask or a defect in the manufacturing process of the regular magnetic medium, the particles come into local contact with each other to form large particles. It is considered that Da / D has increased.

In the conventional medium, the dispersion of the distance between the particles shows a value of ± 50% (FWHM: 100%) or more, and Da reflects the local contact between the particles.
/ D shows a value larger than 1, and Da / D is larger than that of the medium of the present invention at the same dispersion amount of the interparticle distance. This is because, in the conventional medium, not only the variance C′σ of the interparticle distance but also the particle size variance Dσ is large, and the local contact between the particles is larger than that of the medium of the present invention. Conceivable.

Da / D is an amount relating to noise caused by exchange interaction between magnetic particles in terms of magnetic recording characteristics, and is preferably 2 or less. According to this example, even in the regular magnetic particle medium of the present invention, the dispersion of the distance between particles was set to ± 65% (FWHM: 130) in order to make Da / D 2 or less.
%) Or less, and most preferably Da /
The dispersion is ± 40% (FWHM: 80) so that D almost shows 1.
%) Is better.

Example 7 FIG. 13 shows the particle size distribution Dσ (F
WHM) and coercivity squareness ratio S ^*
FIG. 9 is a diagram showing the result of measuring the relationship with. S ^* was derived from the VSM major loop measurement result for the longitudinal medium, and was derived by performing demagnetization correction on the measured value of the saturation magnetization for the perpendicular medium. In FIG. 13, the symbols of A, B, and C are
This is the same as the code used in the fifth embodiment.

The medium of the present invention was measured to have an average particle diameter D of 12 to 13 nm and a dispersion Cσ of interparticle distance of ± 30%.
(FWHM: 60%) The measurement was performed on a medium sample of not more than 60%.

The coercive force squareness ratio S ^* is an amount corresponding to the dispersion of Hc of the magnetic particles. The coercivity squareness ratio S ^* reflects the dispersion of the magnetic properties of the particles (eg, the dispersion of the magnetocrystalline anisotropy) in a range where the particle size is sufficiently large, but does not depend on the particle size itself. Further, when the particle size becomes small and the Hc decreases due to room temperature thermal disturbance, S ^* shows the particle size dependency.

As shown in FIG. 13, in the medium of the present invention, even if the average particle diameter D is as small as 12 to 13 nm, the particle diameter dispersion is adjusted to ± 20% (FWHM: 40%). If so, S ^* indicates a large value. From this, conversely, if the particle size dispersion is larger than ± 20%, a magnetic particle component having a small Hc is also generated in the present invention, and S ^*
It turns out that it reduces.

In a conventional medium, the particle size dispersion is ± 25%
From the above, it can be seen that particles having a reduced Hc due to thermal disturbance are considerably contained. In the conventional medium, S ^* shows a smaller value than that of the medium of the present invention at the same particle size distribution. This is because, in the conventional medium, not only the dispersion of the particle diameter but also the dispersion of the distance between the particles is large, and the dispersion of Hc is further increased because it includes a component in which Hc is apparently increased due to contact between particles. It is thought to be possible.

S ^* is an amount related to recording sensitivity in terms of magnetic recording characteristics. When Hc is the same, the recording sensitivity and the overwrite erasure ratio are improved as S ^* is larger. Therefore, S ^* is preferably 0.5 or more, depending on the recording performance of the head. Therefore, from the results shown in FIG. 8, the particle size dispersion is ± 35% or less (70% by FWHM) even in the regular particle medium of the present invention.
It is understood that it is preferable to set the value to ± 20% or less (40% or less in FWHM) at which S ^* shows a high constant value.

(Example 8) The recording / reproducing characteristics of the medium according to the present invention were evaluated using an MR head. The MR head used had a recording track width of 1.3 μm and a reproduction track width of:
This is a prototype having an AMR reproducing section of 1.0 μm and reproduction gap: 0.1 μm. When the guard band width between tracks is 0.15 μm, this head has a capacity of 4.3 Gb.
It has recording / reproducing ability up to / in ^{2 area} density. Although this head is basically designed for longitudinal recording, it goes without saying that it can also be used for recording and reproduction on a perpendicular medium. For a perpendicular medium, particularly a perpendicular medium of the present invention having a structure in which a NiFe soft magnetic film and a NiFeCo semi-hard magnetic film are provided below a magnetic material, it is preferable to perform recording using a single pole head. However, in the evaluation of the medium noise characteristic of the present invention, a ring type head for a longitudinal direction can be used, so that this head is also used for the perpendicular medium of the present invention.

The minimum recording cell size that can be recorded by this head is 1.3 μm × 0.1 μm, that is, the minimum recording cell has an area of 1.3 × 10E5 (nm ² ). In the regular magnetic particle medium of the present invention, since the magnetic particle interval is 12 to 60 nm, the number of magnetic particles contained in the minimum recording cell is 36 to 902.

The measurement conditions of the recording / reproducing characteristics are as follows: disk rotation speed: 1800 rpm, recording radius position: 22 mm, and flying height of the head: 25 nm. Recording was performed while changing the recording frequency, and the normalized medium noise at each frequency was examined. The recording current was a saturation recording current at which the curve erase ratio became −40 dB or more (to the minus side). The normalized medium noise is the medium noise (Nm) integrated over the entire frequency band.
Is divided by the low-frequency signal output (S0), and is a value normalized per unit length of the reproduction track width (1 μm).

FIG. 14 is a diagram showing an example of the result of measuring the relationship between the spatial recording frequency LD of the medium and the normalized medium noise. In FIG. 14, reference numerals A, B, and C are the same as those used in FIG.

The medium of the present invention measured in this example has a magnetic particle having an average particle size of 15 nm and a particle size dispersion of FWH.
M: 25%, average distance between particles is 18 nm, and dispersion of distribution of distance between particles is adjusted to FWHM: 50%.

From FIG. 14, it can be seen that the medium of the present invention has much lower noise than the conventional medium. This is because, in the medium of the present invention, the dispersion of the particle diameter and the dispersion of the distance between the particles are suppressed as compared with the conventional medium, and the magnetic particles are regularly arranged.

As shown in FIG. 14, in the medium of the present invention, the noise was extremely low in both the medium using CoFe particles (curve A) and the medium using CoPt particles (curve B). The medium using CoPt particles (curve B) is the medium using CoFe particles (curve A).
Lower noise than that. This is because, as shown in FIG. 10, the CoPt particle medium (curve B in FIG. 10) has a lower Mrt than the CoFe particle medium (curve A in FIG. 10), and thus has a higher magnetization in the CoPt particle medium. This is probably because the transition width is narrow and a sharper magnetic transition is formed.

(Embodiment 9) FIG. 15 is a view showing the result of examining the relationship between normalized medium noise and average particle diameter D when a magnetic medium according to the present invention was recorded at a spatial recording frequency of 250 kfci. is there.

In the measurement of the medium of the present invention, the particle diameter dispersion is 25% or less by FWHM, the average value of the distance between particles is an average particle diameter D + (1 to 3 nm), and the dispersion of the particle distance is 50% or less by FWHM. Performed for the medium adjusted to

According to FIG. 15, the spatial frequency is 250 kfci.
In other words, when the recording cell length is approximately 0.1 μm, the noise level is extremely low when the average particle diameter is about 25 nm or less, but the noise level sharply increases when the average particle diameter is 25 nm or more.

When the relationship between the normalized medium noise and the spatial recording frequency was measured (measurement results are not shown), even in the regular magnetic particle medium of the present invention, the magnetic particle diameter was larger than 1/4 of the recording cell length. Also increased, the noise level increased. From this result, it can be seen that in order for the low noise effect to be remarkably exhibited in the medium of the present invention, it is preferable that the particle diameter of the magnetic particles be 1/4 or less of the recording cell length. The number of magnetic particles arranged in the track width direction is not limited at all, as long as the track width during recording is not shorter than the shortest recording cell length. Accordingly, it can be seen that the lower limit of the number of magnetic particles in the track width direction in the minimum recording cell is four.
Actually, several tens or more magnetic particles are arranged in the track width direction of the smallest recording cell.

Example 10 FIG. 16 is a view showing the results of measurement of the relationship among the particle size variance Dσ of the magnetic particles, the variance C′σ of the distance between the particles, and the medium noise. In the measurement, the particle diameter was 1/4 or less of the recording cell length, and the distance between particles was particle diameter + (1
３3 nm) and the recording medium of the present invention and the spatial recording frequency were selected.

In FIG. 16, the solid line summarizes the measurement results of the regular magnetic particle medium of the present invention as contour lines of normalized medium noise. The plot in FIG. 16 is a measurement result of a medium having low noise among conventional media.

From the results shown in FIG. 16, in order for the medium of the present invention to clearly show the low noise effect, the dispersion of the particle diameter is ±
It is understood that the dispersion of the distance between particles is preferably 20% or less (40% or less in FWHM) and ± 40% or less (80% or less in FWHM). More preferably, the dispersion of the particle size is ± 10% or less (20% or less in FWHM), and the dispersion of the distance between the particles is ± 20% or less (40% or less in FWHM).
Most preferably, the dispersion of the particle size is ± 5% or less (F
It can also be seen that the dispersion of the distance between the particles is ± 10% or less (20% or less in FWHM).

In FIG. 16, the noise of the conventional medium is higher than that of the medium of the present invention having the same amount of dispersion. This is because the present invention is based on the regular arrangement of magnetic particles and the dispersion indicates the amount of deviation from the regular arrangement position, whereas the conventional medium basically has an irregular arrangement. Conceivable.

The result shown in FIG. 16 is a result measured using a magnetic head that can be prototyped at the present time. Therefore, in the future, when measurement is performed using a magnetic head having a narrower head gap and improved reproduction resolution, the contour line of the normalized medium noise in FIG. 16 is considered to shift to a larger value. Therefore, when recording is performed using such a head, a magnetic medium in which the distribution of the particle size and the distance between the particles is set to be narrower should be used.

<Preparation of Regular Non-magnetic Pore> (Example 11) A regular non-magnetic pore was prepared according to the method for producing a regular non-magnetic pore medium described above. CoPt and TbCo were used as magnetic materials. In the case of CoPt, as in the case of the regular magnetic particle medium, the axis of easy magnetization was set by the seed layer material, the thickness of the seed layer, the thickness of the magnetic layer, and the conditions for forming the magnetic layer. When TbCo was used, a perpendicular magnetization film was formed without providing a seed layer.

<Evaluation of Regular Nonmagnetic Pore> A sample of the produced regular nonmagnetic pore medium was evaluated in accordance with the evaluation of the regular magnetic particle medium. The evaluation of the microstructure of the regular non-magnetic pore medium is based on the average pore diameter (P ') and the FWH of the pore diameter distribution.
M (P'σ), average pore spacing (C), F of pore spacing distribution
This was performed using WHM (C′σ). The values of these parameters are the parameters of the self-assembled mask obtained in Example 1, that is, the average pore size and the FW of the pore size distribution.
The value is obtained by adding the value due to the process variation to the HM, the average hole interval, and the FWHM of the hole interval distribution. The range of P ′, P′σ, C, C′σ in the present embodiment is the average particle diameter D of the regular magnetic particle medium obtained in Example 3, and the FWHM of the particle size distribution.
Dσ, the average distance C between the magnetic particles, and the distribution of the distance between the magnetic particles were almost equal to the range of FWHMC'σ.

(Example 12) First, MFM observation was performed to evaluate a domain wall. As a result of MFM observation, when TbCo is used for the magnetic material, the width of the domain wall depends on the composition ratio and the film thickness.
It was 10-20 nm. When CoPt was used for the magnetic material, the width of the domain wall was 7 to 13 nm. The width of the domain wall becomes narrower as the anisotropic energy becomes larger.
Even when Pt has a composition of Co: 50 at%, the domain wall width is 5
When SmCo having large magnetic anisotropy is used, the width of the domain wall is estimated to be 3 to 6 nm. Thus, it can be seen that the nonmagnetic pore diameter in the present invention can be variously adjusted depending on the type of the magnetic material used.

(Example 13) The relationship between the average spacing C 'between non-magnetic pores and the product (Mrt) of residual magnetization and film thickness was measured. The measurement results showed an inverse correlation to the correlation between C and Mrt for the regular magnetic particle medium shown in FIG. That is, the larger the C ', the greater the occupation ratio of the magnetic material, and thus the Mrt increased. The relationship between Mrt and C ′ was as predicted from the calculation, and it was found that appropriate adjustment of Mrt was easy even in a regular non-magnetic pore medium.

(Example 14) The relationship between the average pore diameter P 'of the nonmagnetic pore and the coercive force Hc was measured. The measurement results showed the same relationship as the relationship between the average particle size D and the coercive force Hc for the regular magnetic particle medium shown in FIG. That is, when P ′ is 以下 or less of the domain wall width, Hc
Fell. This is because when the diameter of the nonmagnetic pore is equal to or more than １ ／ of the domain wall width, the nonmagnetic pore acts as a pinning site of the domain wall, so that a large Hc is developed. Is not pinned by the pores and moves freely, so that Hc decreases.

(Example 15) Dispersion C 'of non-magnetic pore spacing
σ, activated size Da of non-magnetic pore and average pore diameter P ′
And the ratio Da / P ′ was measured. The measurement result showed an extremely large value of Da as compared with Da shown in FIG. This is because the value of Da is very large because the magnetic base material is connected throughout the film surface. From the measurement results, it was clarified that the regular non-magnetic pore medium of the present invention had no influence of thermal disturbance unlike the multi-particle or regular magnetic particle medium.

(Example 16) Dispersion C 'of non-magnetic pore spacing
The relationship between σ and the coercivity squareness ratio S ^* was measured. As a result of the measurement, when the average pore diameter P ′ was small, S ^* decreased as the pore diameter dispersion P′σ increased, as in the case of the regular magnetic particle medium shown in FIG. This is due to the fact that as the pore diameter dispersion P′σ increases, a pore diameter smaller than 未 満 of the domain wall width appears. However, when the average pore diameter P ′ is relatively large, or when the pore diameter dispersion P′σ is sufficiently small, S ^* is 1
It showed a value close to.

(Example 17) The relationship between the spatial recording frequency LD of a non-magnetic pore medium and the normalized medium noise was measured using the MR head used for evaluation of the regular magnetic particle medium. The measurement results show that the pore diameter is adjusted between 1/2 and 3 times the domain wall width, and the variance of the gap between the pores is C'σ of ± 40%.
(80% in FWHM)
As with the measurement results for the regular magnetic particle medium of FIG. 14, low noise performance was exhibited.

(Embodiment 18) FIG. 17 shows the relationship between the normalized medium noise at 250 kfci and the ratio P ′ / δ between the average pore diameter P ′ and the domain wall width δ for a non-magnetic pore medium. It is a measurement result. The measurement was performed using the FWHM of the pore spacing distribution.
This was performed on a medium in which (C′σ) was adjusted to 80% or less.

FIG. 17 shows that when P '/ δ is in the range of 1/2 to 3, the non-magnetic pore medium according to the present invention exhibits good low noise performance. When P ′ / δ is less than 未 満, the noise rises because the domain wall moves without being pinned by the pore, and the position of the domain wall is not determined, and the magnetization transition portion is disturbed. When P ′ / δ is greater than 3, the noise rises because the domain wall is pinned to the pore and the shape of the magnetization transition portion of the domain wall is good, but the pore diameter is too large. This is because the magnetic pore itself becomes a noise source.

(Embodiment 19) FIG. 18 is a measurement result showing the relationship between the normalized medium noise at 250 kfci and the FWHM (C'σ) of the pore interval distribution for a non-magnetic pore medium. The measurement was performed on a non-magnetic medium in which P ′ / δ was adjusted in the range of 1/2 to 3.

As shown in FIG. 18, when C'σ is 8
At 0% or less, noise gradually increases with an increase in C'σ, and when C'σ exceeds 80%, noise rapidly increases.

As a result of SEM observation and MFM observation, if C′σ exceeds 80%, the pore diameter depends on the pore diameter. It has been found that the shape of the magnetization transition is disturbed because the domain walls are connected to each other other than the pores arranged along the magnetization transition.

[0245]

As described in detail above, according to the present invention, a magnetic recording medium capable of improving S / N and realizing high density and a method of manufacturing the same are provided. As a result, a practical thermal agitation resistance at a memory operating temperature and a medium S / N required by the system can be achieved without excessively miniaturizing the magnetic particles and excessively increasing the anisotropic energy of the magnetic particles. Can be compatible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a regular magnetic particle medium according to the present invention.

FIG. 2 is a schematic view showing an example of a regular non-magnetic pore medium according to the present invention.

FIG. 3 is a schematic sectional view showing an example of the anodic oxidation barrier layer and porous alumite according to the present invention.

FIG. 4 is a schematic view showing a metal ring according to the present invention.

FIG. 5 is a process flow chart showing an example of a manufacturing method according to the present invention.

FIG. 6 is a schematic view showing an example of a servo pattern of the magnetic disk according to the present invention.

FIG. 7 is a schematic view showing an example of an apparatus for producing a regular magnetic particle medium according to the present invention.

FIG. 8 shows the SE of a mask experimentally manufactured in the embodiment of the present invention.
The figure which shows an M image.

FIG. 9 is a view showing an SEM image of a regular magnetic particle medium experimentally manufactured in an example of the present invention.

FIG. 10 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 11 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 12 is a diagram showing the results of evaluation of a regular magnetic particle medium in an example of the present invention.

FIG. 13 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 14 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 15 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 16 is a view showing a result of evaluating a regular magnetic particle medium in an example of the present invention.

FIG. 17 is a view showing a result of evaluating a regular non-magnetic pore medium in an example of the present invention.

FIG. 18 is a view showing a result of evaluating a regular non-magnetic pore medium in an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Seed layer 3 ... Magnetic recording layer 4 ... Non-magnetic matrix 5 ... Magnetic particle 6 ... Protective layer 7 ... Minimum recording cell 8 ... Continuous magnetic film 9 ... Non-magnetic pore 10 ... Domain wall 11 ... Al plate 12 ... Barrier layer part 13 ... Micropore 14 ... Porous alumite part 15 ... Metal ring 16 ... Opening part 20 ... Vacuum container 21 ... Induction heating type evaporation source 22 ... Heater 23 ... Crucible 24 ... Shutter 25 ... RF power supply 26 ... Evaporation sample 27 ... Superconductor part 28 Cold head 29 Superconductor 30 Magnetic disk substrate 31 Magnetic field application coil 32 Magnetic field

Claims (8)

[Claims] A plurality of magnetic particles arranged in a continuous non-magnetic film, wherein the number of magnetic particles contained in the smallest magnetic recording cell is at least four arranged in a track length direction; The full width at half maximum of the distribution of the distance between nearest neighbor particles is ± 40% or less of the average distance between the nearest particles, and the full width at half maximum of the particle size distribution is ± 20% or less of the average particle size. Magnetic recording medium. 2. A semiconductor device comprising: a plurality of non-magnetic pores arranged in a continuous magnetic film; wherein a magnetization transition portion in the magnetic film comprises a domain wall connecting the non-magnetic pores; A magnetic recording medium having a width of 0.5 to 3 times the width. 3. The full width at half maximum of the distribution of the distance between the nearest pores in the smallest magnetic recording cell is ± 4 of the average distance between the nearest pores.
3. The magnetic recording medium according to claim 2, wherein the content is 0% or less. 4. A step of (a) disposing a mask having openings arranged by self-assembly on a continuous nonmagnetic film; and (b) irradiating an ion beam from above the mask into the continuous nonmagnetic film. A method for producing a magnetic recording medium, comprising: a step of forming a plurality of arranged holes; and (c) a step of filling the holes with a magnetic substance to form magnetic particles. 5. A step of (a) disposing a photosensitive layer on the continuous magnetic film; (b) a step of disposing a mask having openings arranged by self-assembly on the photosensitive layer; Irradiating the photosensitive layer with light or electrons from above to expose the photosensitive layer, and then developing the photosensitive layer to form a mask pattern in which a portion corresponding to the opening remains; and (d) continuously forming a mask pattern according to the mask pattern. A method for manufacturing a magnetic recording medium, comprising: a step of forming a plurality of magnetic particles arranged in a magnetic film; and (e) a step of filling a nonmagnetic material between the magnetic particles. 6. The method according to claim 1, wherein a plurality of magnetic particles are arranged in the continuous non-magnetic film, and the number of magnetic particles contained in the smallest magnetic recording cell is at least the number of particles arranged in the track length direction. Four, and the full width at half maximum of the distribution of the distance between the closest particles is ± 40 of the average distance between the closest particles.
% Or less, and the full width at half maximum of the particle size distribution is ± 20 of the average particle size.
%. The method for manufacturing a magnetic recording medium according to claim 4, wherein the magnetic recording medium is manufactured at a ratio of not more than 10%. 7. A step of (a) disposing a mask having openings arranged by self-organization on a continuous magnetic film; and (b) irradiating an ion beam from above the mask to be arranged in the continuous magnetic film. Forming a plurality of holes, and (c) forming a non-magnetic pore by filling the holes with a non-magnetic material. 8. The method according to claim 1, wherein each of the steps includes a plurality of non-magnetic pores arranged in the continuous magnetic film, wherein a magnetic transition portion in the magnetic film comprises a domain wall connecting the non-magnetic pores. 8. The method according to claim 7, wherein a magnetic recording medium having a diameter of 0.5 to 3 times the average width of the domain wall is manufactured.