JP2001250222A - Magnetic recording medium, its producing method and magnetic recorder using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium capable of high density recording. SOLUTION: The magnetic recording medium has a substrate, a base film formed on the substrate and comprising grains comprising one or more metals or alloys each having a body-centered cubic structure and one or more selected from oxides, nitrides and borides of the groups I-V elements of the periodic table and one or more metals or alloys each having a body-centered cubic structure and one or more selected from oxides, nitrides and borides of the groups I-V elements of the periodic table as components constituting the grain boundaries of the grains and a magnetic film formed on the base film directly or by way of another layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-performance and high-reliability magnetic recording device, a magnetic recording medium for realizing the same, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a highly information-oriented society has been remarkably advanced, and multimedia integrating various forms of information has rapidly spread. One of the information recording devices supporting this is a magnetic recording device such as a magnetic disk device. At present, the recording density and the size of the magnetic disk drive are being improved. Further, the cost of magnetic disk drives has been rapidly reduced.

By the way, in order to realize a higher density of a magnetic disk drive, (1) decrease the distance between the magnetic disk medium and the magnetic head, and (2) increase the coercive force of the magnetic disk medium. And 3) devising a signal processing method is a technical problem.

Among them, the magnetic disk medium has two
In order to realize a recording density exceeding 0 Gb / in ² , in addition to increasing the coercive force, the unit in which the magnetization reversal of the magnetic film occurs must be reduced. Therefore, it is necessary to reduce the size of the magnetic particles constituting the magnetic film.

[0005] Further, it has become important to make the size of magnetic particles finer and to make the size distribution uniform, from the viewpoint of reducing thermal fluctuations.

As a method for controlling the size of magnetic particles and the distribution of the sizes in a magnetic film, US Pat.
As described in US Pat. No. 2,499, it has been proposed to provide a seed thin film under a magnetic film. Further, it has been proposed to separate crystal grains of a magnetic thin film by non-ferromagnetic and non-metallic crystal grain boundaries (Japanese Patent Application Laid-Open Nos. 7-31929 and 11-66533).

[0007]

However, in such a conventional technique, there is a limit in controlling the crystal grain size and the distribution of the crystal grain size of the magnetic film constituting the magnetic disk medium. And coarse particles coexisted. In the magnetic film in such a state, when recording information (when reversing the magnetization), it is affected by a leakage magnetic field from surrounding magnetic particles, and conversely, large magnetic particles interact with each other. When performing high-density recording exceeding ²⁰ Gb / in ² , stable recording may not be performed.

[0008] A first object of the present invention is to provide a high-performance magnetic recording medium in which noise is less generated by reducing the size of magnetic particles in a magnetic film.

A second object of the present invention is to provide a magnetic recording medium having low noise, low thermal fluctuation, and low thermal demagnetization by uniformly controlling the distribution of magnetic particle sizes.

A third object of the present invention is to provide a magnetic recording medium suitable for high-density recording by controlling the crystal orientation of a magnetic film.

A fourth object of the present invention is to provide a magnetic recording medium in which the unit of magnetization reversal during recording or erasing is reduced by reducing the magnetic interaction between magnetic particles.

A fifth object of the present invention is to provide a 20 Gb / in ^2.
It is an object of the present invention to provide a magnetic recording device capable of performing ultra-high density recording exceeding.

A sixth object of the present invention is to provide a material and a method for manufacturing a magnetic recording medium.

[0014]

The gist of the present invention to achieve the above object is as follows.

A substrate, at least one metal or alloy having a body-centered cubic structure formed on the substrate, and at least one of Periodic Tables I to V
Particles of at least one of oxides, nitrides, and borides of group III, at least one of metals or alloys having a body-centered cubic structure constituting grain boundaries of the particles, and Periodic Tables I to V The present invention relates to a magnetic recording medium having a base film made of at least one of oxides, nitrides, and borides of group III and a magnetic film formed directly or through another layer on the base film.

As the metal or alloy having the body-centered cubic structure, Cr or one of Cr alloys is particularly preferable.

The particles of the base film are 65 to 98% by weight of a metal or alloy having a body-centered cubic structure, and one or more of oxides, nitrides and borides of Groups I to V of the periodic table. The grain boundary phase separating the particles is at least one of a metal or alloy having a body-centered cubic structure constituting the particles, and an oxide or nitride of Group I to V of the periodic table. And at least one of boride.

The substance constituting the particles and their grain boundaries and the concentration (composition) can be adjusted by selecting the materials or film forming conditions. At the same time, it is possible to control the orientation of the film, the crystal grain size and the distribution by selecting a material or selecting film forming conditions.

In the magnetic recording medium of the present invention, the undercoat film has a particle size of 15 to 3.5 nm, its standard deviation (σ) is 25% or less of the average particle size,
The major axis is 0.7 to 1, the width of the grain boundary phase separating each particle is 0.1 to 2 nm, and the particles are crystalline (measurable as crystalline by electron beam diffraction). Are regularly arranged two-dimensionally. A structure in which an amorphous grain boundary (a lattice image is not confirmed by a structure analysis of the film surface by a transmission electron microscope) is preferably present at a crystal grain boundary of the particle is present.

Most preferably, the crystal grains are crystal-oriented so that the lattice constant of the magnetic film particles can be easily matched.

The object of the present invention can be achieved when the thickness of the underlayer is 5 to 100 nm. If the thickness is less than 5 nm, the base film is affected by the substrate, and sufficient characteristics as the base film cannot be obtained. On the other hand, if the thickness exceeds 100 nm, there is no problem in the characteristics of the base film itself, but it takes time to form the film, which is not preferable from the viewpoint of production.

As the magnetic film to be formed on the underlayer directly or via another layer, a ferromagnetic thin film containing one or more of Co and an alloy mainly containing Co is used. This magnetic film has Cr, Ta, N at the grain boundaries of crystal grains mainly composed of Co.
b, a structure in which one or more other elements are present, or one or more of Cr, Ta, Nb, and other elements at grain boundaries and oxides, nitrides, borides of Groups I to V of the periodic table ,
Is a structure in which one or more of

A feature of the present invention is that a magnetic film is grown on the underlayer, and the particle size and particle size distribution of the underlayer can be reflected on the particle size and particle size distribution of the magnetic film. It is in the point that found.

Further, a magnetic film is formed by forming at least one element of Cr, Ta, Nb, and other elements and oxides, nitrides of Group I to V of the periodic table on grain boundaries of crystal grains mainly composed of Co, By providing at least one type of boride, a magnetic film can be more reliably grown on the base film while reflecting the form of the base film.

In the present invention, Co or an alloy mainly containing Co can be used as the magnetic particle component of the magnetic film.

In the magnetic recording medium to which the above-described technique of the present invention is applied, the unit in which the magnetization reversal occurs is 100 nm or less,
The coercive force is 2 kOe or more.

The magnetic recording medium of the present invention comprises a target made of a metal or an alloy having a body-centered cubic structure, more preferably one or more of Cr or a Cr alloy, directly on a substrate or through another layer; Forming a base film by simultaneously performing sputtering using a target composed of at least one of oxides, nitrides, and borides of Groups I to V of the periodic table and adjusting the composition on the substrate; A magnetic recording medium can be manufactured by forming a magnetic film by growing magnetic particles directly or through another layer.

A mixture of a metal or alloy having a body-centered cubic structure, more preferably one or more of Cr or a Cr alloy, and one or more of oxides, nitrides, and borides of Groups I to V of the periodic table. A magnetic recording medium can be manufactured by forming a magnetic film by performing sputtering using a target made of a sintered body, forming a base film, and growing magnetic particles on the base film directly or through another layer. .

Further, a metal or an alloy having a body-centered cubic structure, more preferably one or more metals or alloys having a body-centered cubic structure of Cr or a Cr alloy, may have
At least 98% by weight of a sintered body of a metal or alloy having a body-centered cubic structure is melted or sintered with at least one of oxides, nitrides and borides of Groups I to V of the periodic table. A magnetic recording medium in which a base film is formed using a target for forming a base film provided on a sintered body of a metal or an alloy having the body-centered cubic structure, and a magnetic film is formed by growing magnetic particles on the base film. Is also possible.

One or more of Co and a Co alloy may be used in the amount of 65 to 9
8% by weight and 35 to 2% by weight of at least one of oxides, nitrides and borides of Groups I to V of the periodic table, and using a sintered magnetic film forming target, It is also possible to produce a magnetic recording medium on which magnetic particles are grown.

One or more of the Co and Co alloys are melted or sintered with at least one of Co and the Co alloy so that the content of the at least one of the Co and the Co alloy is 65 to 98% by weight in the magnetic film. It is also possible to produce a magnetic recording medium in which magnetic particles are grown on a base film using a target for forming a magnetic film provided with at least one melt or sintered body of oxides, nitrides and borides of group V. is there.

Here, in order to smoothly grow the particles, it is preferable that the crystal structure of the crystal particles in the underlayer is the same as or similar to the structure of the magnetic particles constituting the magnetic film. Note that the similarity means that the difference between the lattice constant of the crystal grains of the base film and the lattice constant of the magnetic particles constituting the magnetic film is preferably within ± 10%. Further, in order to allow the crystal to grow smoothly, it is desirable to be within ± 5%.

As described above, when the magnetic film is grown from the base film via another layer as the case may be, the shapes and sizes of the crystal grains of the base film and the magnetic film become substantially equal. That is, the size of the crystal grains in the magnetic film is determined by the size of the crystal grains in the base film.

Thus, the crystal grains of the magnetic film are miniaturized, and the size distribution becomes uniform. Specifically, the average particle diameter of the crystal particles of the magnetic film is 15 to 3.5 nm,
The average particle diameter can be controlled to 25% or less of the standard deviation σ. In addition, the crystal grains in the underlayer are refined, and the size distribution is uniform and regularly arranged. Therefore, the crystal grains of the magnetic film formed thereon are also refined, and the size thereof is reduced. Is uniform and the particles are regularly arranged. Therefore, noise, thermal fluctuation and thermal demagnetization caused by the magnetic recording medium can be reduced.

As described above, the unit of magnetization reversal and the size thereof can be reduced in the magnetic recording medium. The magnetization reversal unit as used herein means the minimum unit of reversal is the crystal grain 1 of the magnetic film.
It is determined by observing with a magnetic force microscope (MFM) or the like how many crystal grains correspond to the recording or erasing when recording or erasing is performed.

As described above, it is preferable to use a ferromagnetic thin film containing one or more elements of Co or a Co alloy as the magnetic film. Further, the structure of this ferromagnetic thin film is C
At least one of Cr, Ta, Nb, and other elements is segregated at the grain boundaries of the crystal grains of o. In addition, one of oxides, nitrides and borides of groups I to V of the periodic table is formed on the ferromagnetic thin film.
It is effective to add more than seeds.

It is possible to provide a high-density recording magnetic disk device equipped with a drive mechanism for mounting and rotating the magnetic recording medium of the present invention and a magnetic head for recording and reproducing data on and from the magnetic recording medium.

In the magnetic disk drive equipped with the magnetic recording medium of the present invention, the magnetic particles of the magnetic film can be controlled by reflecting the particle size and the particle size distribution of the crystalline particles in the underlayer. The magnetic film that grows on the crystalline grains and on the amorphous grain boundaries has a zigzag pattern existing in the magnetization transition region because the magnetic interaction between the crystal grains constituting the heteromagnetic film is reduced. Can be smaller.

More specifically, the width of the zigzag pattern existing in the magnetization transition region of the track of the magnetic recording medium can be made smaller than the gap length of the recording head. Note that the width of the zigzag pattern does not necessarily have to be equal to or less than the gap length over the entire circumference of the track, but is ideally equal to or less than the gap length over the entire circumference. Thereby, noise of the magnetic recording medium can be reduced. Further, even if the track width is reduced, the influence of noise can be suppressed to a small value, so that the track density can be reduced.

A magnetic recording apparatus using this magnetic recording medium can realize high-density recording exceeding ²⁰ Gbit / in ² . As a result, various information such as images, code data, and audio can be recorded, reproduced, or deleted.

Incidentally, the information recording method of the magnetic recording medium includes:
Broadly, there are an in-plane recording method in which the recording magnetization is formed in the film surface direction, and a perpendicular recording method in which the recording magnetization is formed perpendicular to the film surface.

For the magnetic layer of the longitudinal recording medium, a Co alloy having a hexagonal closest structure is used. Since the Co alloy film has uniaxial anisotropy with the c-axis as the axis of easy magnetization, the c-axis is oriented in the film plane. Further, a Co alloy or the like having a hexagonal closest structure is also used for the perpendicular recording medium. In this case, the c-axis is oriented perpendicular to the film surface.

The orientation of the magnetic film can be controlled by the conditions for forming the underlayer and the magnetic film. Therefore, the technique of the present invention can be used for both the longitudinal recording method and the perpendicular recording method.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.

[Embodiment 1] In this embodiment, by forming a magnetic film on a base film whose grain size is controlled, the grain size and the grain size distribution of the magnetic film are controlled, and the axis of easy magnetization is reduced. A magnetic recording medium and a magnetic recording device perpendicular to the substrate surface will be described.

FIG. 1 shows a cross-sectional structure of a thin film of a magnetic recording medium prepared according to the present invention.

As the substrate 1, a glass substrate having a diameter of 2.5 inches was used. After cleaning the substrate 1, a base film 2 was formed. In this embodiment, a Cr sintered target and a target obtained by mixing silicon oxide (SiO ₂ ) and titanium oxide (TiO ₂ ) at a molar ratio of 1: 1 and sintering them on a substrate 1 as a base film are used. A base film 2 having a thickness of 10 nm was formed by the simultaneous sputtering method.

Pure Ar gas was used as the discharge gas during sputtering, the discharge gas pressure was 5 mTorr, the applied high frequency power was 100 to 400 W / 100 mmφ on the Cr side, and 100 to 1000 W / 100 mmφ on the SiO ₂ and TiO ₂ sides. .

Next, on the base film 2, 12
a Co ₆₉ Cr ₁₉ Pt ₁₂ film (atomic%) with a thickness of 10 nm
Formed. Pure Ar gas was used as a discharge gas during sputtering. Discharge gas pressure is 3mTorr, DC input
The power is 300 W / 100 mmφ.

Next, a carbon (C) film having a thickness of 5 nm was formed as a protective film 4 on the magnetic film 3. The conditions at the time of sputtering were as follows: the discharge gas was Ar, the discharge gas pressure was 5 mTorr,
The input DC power is 800 W / 100 mmφ. Finally, a lubricating film 5 was formed to obtain a magnetic recording medium 6.

Table 1 shows the results. Except for Comparative Example No. 8, the average particle diameter of the base film was 3.5 to 7 nm, the minor axis / major axis of the particles was 0.85 or more, and the standard deviation (σ) / particle diameter × 100.
Was 25% or less.

The values of the average particle diameter, the minor axis / major axis, and the standard deviation (σ) / particle diameter × 100 of the magnetic films formed on the No. 1-No. Was reflected.

[0053]

[Table 1]

FIG. 2 shows the surface of the underlayer No. 3 in Table 1 as TE.
The result observed by M is shown as a representative example. Particles 6 having an average particle diameter of 6.4 nm were regularly arranged. The grain boundaries 7 of the particles 6 were 0.1 to 0.5 nm.

Here, the composition of the grain portion and the grain boundary portion is FE-
EDX of TEM (Field Emission TEM)
(Energy dispersive X-ray spectrometer). The particle portion was measured with a beam diameter of about 5 nm, and the grain boundary portion was measured with a beam diameter of about 0.5 nm. The particles are 65 Cr
９５95% by weight, with the balance being SiO ₂ + TiO ₂ .

The grain boundary was 70% in total of SiO ₂ and TiO _2, and the balance was Cr. Further, when the structure of the underlayer was observed by electron beam diffraction, the grain portion was crystalline and the grain boundary portion was not clear in the electron beam diffraction image.
Since a lattice image indicating that the grain boundary portion was crystalline was not confirmed in a transmission electron microscope (TEM) image, it was found that the grain boundary was amorphous.

The particle diameter of the particles constituting the base film is as follows:
As a representative example, the area of about 300 particles in a TEM observation photograph of the surface of the base film as shown in FIG. 2 was measured, and the area of each particle was approximated by a circle to determine the diameter as the particle diameter.

The crystal orientation of the formed base film was evaluated by X-ray diffraction. The measured X-ray diffraction line is Cr (110)
Since it was only the film, it was found that the film was strongly oriented to (110).

In the X-ray diffraction evaluation of the magnetic film, Co (001)
Since only the magnetic film was measured, the magnetic film was oriented to Co (001), and the axis of easy magnetization was perpendicular to the substrate surface.

The particle size of the crystal particles varies depending on the conditions at the time of sputtering. In this embodiment, the base film is formed under the condition that fine particles having a base film in the range of 3.5 to 7 nm can be formed. The particle size of the magnetic film was controlled by the particle size of the underlying film, and became fine particles.

In this embodiment, the Ar gas is used as the discharge gas, but a gas containing nitrogen may be used instead. As a result, the film can be densified, and the performance can be improved.

As a result of measuring the magnetic characteristics of the magnetic film formed by the above method, the coercive force was 3.0 to 3.8 kOe, and the coercive force squareness ratio S, which is an index of the squareness of hysteresis in the MH loop, was measured. * Was 0.7 to 0.88, indicating good magnetic properties.

Further, after applying a lubricant 5 to the surface of the magnetic recording medium, it was incorporated into a magnetic recording / reproducing apparatus, and the recording / reproducing characteristics were evaluated.

FIG. 3 is a schematic perspective view of the magnetic recording apparatus used in this embodiment. Magnetic recording medium 16, drive unit (rotation) 14 for rotating this, drive unit (recording) 15 for recording on magnetic recording medium 16, signal input to magnetic head 11, and output signal from magnetic head 11 Is a magnetic storage device provided with a recording / reproducing signal processing means for reproducing the data.

The magnetic head 11 comprises a reproducing head and a recording head. The recording head has an upper magnetic core, a lower magnetic core, and a gap film.

Here, the gap film of the recording head has 2.
Using a soft magnetic film having a high saturation magnetic flux density of 1T,
The gap length is 0.15 μm. A magnetic head having a giant magnetoresistance effect was used as a reproducing head.

The distance between the medium facing surface of the magnetic head and the magnetic film of the magnetic recording medium is 20 nm. 20 for magnetic recording media
When a signal corresponding to Gb / in ² was recorded and the S / N was evaluated, a reproduced output of 25 to 36 dB was obtained with the magnetic films formed on the base films Nos. 1 to 7 in Table 1.

On the other hand, No. 8 in Table 1 shown as a comparative example
The reproduction output of 17 dB was obtained from the magnetic film formed on the underlayer.

Here, when the magnetization reversal unit of the magnetic film was measured by a magnetic force microscope (MFM), it was found that the sample of the present invention was about 2 to 3 particles, and was sufficiently small. Also, the region where the zigzag pattern of the magnetization transition region measured by a magnetic force microscope (MFM) exists is 0.1%.
μm and less than the gap length of the recording head, which was extremely small.

Further, neither thermal fluctuation nor demagnetization due to heat occurred. This is because the distribution of the crystal grain size of the magnetic film is small.

The mixing ratio of Cr, SiO ₂ and TiO ₂ can be appropriately selected depending on the film forming conditions as shown in Table 1. Although glass is used as the substrate in this embodiment, an Al or Al alloy substrate or a substrate made of a synthetic resin can be used, and the substrate size can be changed.

Further, a layer for modifying the surface of the substrate such as NiP, CoCrZr or the like may be formed on the substrate.

[Embodiment 2] In this embodiment, the magnetic film formed on the underlayer film whose grain size and orientation is controlled has its grain size and orientation controlled in accordance with the shape of the underlayer film. A magnetic recording medium and a magnetic recording device whose easy axis is parallel to the substrate surface will be described.

The structure of the film is: substrate / base film / magnetic film / protective film / lubricating film. The production method is described below.

First, a glass substrate having a diameter of 2.5 inches was used as a substrate. As a base film 2 on a substrate 1, a Cr sintered target and a target obtained by mixing silicon oxide (SiO ₂ ) and titanium oxide (TiO ₂ ) at a molar ratio of 1: 1 and sintered were used. A base film 2 having a thickness of 20 nm was formed from both targets by a simultaneous sputtering method.

A pure Ar gas was used as a discharge gas at the time of sputtering, the discharge gas pressure was 2 mTorr, the applied high frequency power was 500 to 1000 W / 100 mmφ on the Cr side, SiO ₂
And the TiO ₂ side was 60 to 100 W / 100 mmφ.

Next, 12 .mu.m is formed on the underlying film 2 by sputtering.
a Co ₆₉ Cr ₁₉ Pt ₁₂ film (atomic%) with a thickness of 10 nm
Formed. Co-C for sputtering target
An r-Pt alloy was used, and pure Ar gas was used as a discharge gas.
The discharge gas pressure is 3 mTorr, the input DC power is 300
W / 100 mmφ.

Next, a carbon (C) film having a thickness of 5 nm was formed as a protective film 4 on the magnetic film 3. The conditions at the time of sputtering are as follows: the discharge gas is Ar gas, and the discharge gas pressure is 5 mTorr.
r, DC power input is 800 W / 100 mmφ. Finally, a lubricating film 5 was formed to obtain a magnetic recording medium. Table 2 shows the results of this example.

[0079]

[Table 2]

The average particle diameter of the underlayer film was 8 to 15 nm except for Comparative Example No. 4, the minor / major axis of the particles was 0.85 or more, and the value of standard deviation (σ) / particle diameter × 100 was 25%. It was below. In addition, the average particle diameter of the magnetic films formed on the base films No. 1 to No. 3, the minor axis / major axis of the particles, and the standard deviation (σ) /
The value of particle diameter × 100 well reflected the morphology of the underlying film.
The grain boundary 8, which is the interval between the particles 7, was 0.1 to 0.5 nm.

Here, the composition of the particle portion and the grain boundary portion was FE
-EDX of TEM (Field Emission TEM)
(Energy dispersive X-ray spectrometer). The particle diameter was measured at a beam diameter of about 5 nm, and the grain boundary area was measured at a beam diameter of about 0.5 nm.

Further, the structure of the underlayer was observed by electron beam diffraction. As a result, the grain portion was crystalline, and the grain boundary portion was not clear in the electron diffraction image, but a lattice image showing that the grain boundary portion was crystalline was confirmed in a transmission electron microscope (TEM) image. Since it was not performed, it was found to be amorphous.

The crystal orientation of the formed base film was evaluated by X-ray diffraction. The measured X-ray diffraction line is Cr (100)
The film was strongly oriented. Under the conditions for forming the underlayer,
The differences from the first embodiment are mainly the film thickness, Cr and SiO ₂
+ TiO ₂ composition ratio and gas pressure. By controlling these conditions, the grain size of the underlayer is increased, and the orientation is changed from Cr (110) to Cr (100).
This is a film that is strongly oriented.

In the X-ray diffraction evaluation of the magnetic film formed on the underlayer strongly oriented to Cr (100), the magnetic film was oriented to Co (110), and the axis of easy magnetization was parallel to the substrate surface. Was. In addition, the particle size of the magnetic film was controlled by the particle size of the underlayer, and the particles had a size corresponding to the underlayer.

The characteristics of the magnetic recording medium of the present example thus manufactured were evaluated in the same manner as in Example 1, and good characteristics were recognized.

In the comparative example of No. 4 in Table 2, the average particle size was 19.7 nm, (standard deviation of particle size) / average particle size was 28.6%, etc. The distribution was poorly controlled.

This is because the particle constituting component of the underlayer is 99.5.
% By weight, and it is considered that the grain boundaries could not be sufficiently formed. Including the results of Example 1, the proper composition range of the present invention is as follows.
It is.

[Embodiment 3] Cr target and Si
Using a soda lime-based glass containing O ₂ —Na ₂ O—CaO as a main component, Si ₃ N ₄ , TiN, Fe ₂ B, and CoB as targets, forming a 30-nm-thick base film by simultaneous sputtering of both targets did.

Pure Ar gas was used as a discharge gas during sputtering, the discharge gas pressure was 1 mTorr, the applied high frequency power was 600 W on the Cr side, and 100 W on the target side on the soda lime glass side.

During the film formation, the substrate was heated to 300.degree. Observation of the surface of the base film by TEM revealed that the average particle size was 9.8 to 12.5 nm, that the crystal particles had a minor axis / major axis of 0.7 or more, and that amorphous particles were formed around the crystal grains. It was found that grain boundaries existed. The particles are crystallized, and the particle size distribution (σ) of the particles is 16.8 of the average particle size.
２０20.8%. The thickness of the grain boundary between the crystal grains was 0.5 to 1.0 nm.

Example 4 A glass substrate having a diameter of 2.5 inches was used as a substrate. No. 1 of Example 1 was added to this substrate.
An underlayer was formed under the same conditions as in No.3.

As a magnetic film on the underlayer, a target obtained by mixing and sintering silicon oxide and titanium oxide at a molar ratio of 1: 1 and a Co—Cr—Pt alloy target were simultaneously sputtered to obtain a magnetic film. A film was formed.

A sintered body of 95% by weight of a Co—Cr—Pt alloy and 5% by weight of a powder mixture obtained by mixing silicon oxide and titanium oxide at a molar ratio of 1: 1;
The -Pt alloy 95 wt% and SiO ₂ -Na ₂ O-CaO-based mixture of glass powder 5% by weight of the sintered body as a target,
A magnetic film was formed by sputtering. The thickness of the magnetic film was 10 nm. Table 3 shows the results of this example.

[0094]

[Table 3]

The cross section of the formed magnetic film was observed with a TEM, and a schematic diagram thereof is shown in FIG. As shown, the cross-sectional structure of the underlayer / magnetic film laminate is composed of magnetic crystalline particles 7 'and amorphous grain boundaries 8', and the magnetic film 3 reflects the form of the underlayer well. Was growing.

From these results, it is possible to further control the particle size and distribution of the underlying film by coexisting the magnetic film forming particle component and the grain boundary forming component also in the magnetic film.

Example 5 Cr having an average particle size of 2.3 μm
And Cr-20Ti (at.%) Powder with Na ₂ O—S
iO ₂ -CaO-based glass or a molar ratio of 1: 1 and so as mixtures metered special grade of SiO ₂ and TiO ₂ were prepared in the proportions shown in Table 4.

Ethanol was added to these blends to form a uniform mixture in the form of a slurry, which was dried with a spray dryer and granulated. Thereafter, the pressed body was subjected to hot isostatic press sintering.

Using each sintered body as a target, a 30-nm-thick base film was formed by high-frequency sputtering. Table 4 shows the composition of each target, the crystallinity and average particle diameter and the standard deviation / average particle diameter of the base film formed by each target, and the film composition of this example.

[0100]

[Table 4]

On the base films of Nos. 1 to 10 in Table 4, 10 n
m of magnetic film (Co ₆₉ Cr ₁₉ Pt ₁₂ ) was formed. Using the medium thus obtained, a magnetic disk device was manufactured, and a 20 G
Table 4 shows the S / N ratio when data corresponding to b / in ² is written and read.

No. 1 in Table 4 is a comparative example, in which the amount of Cr in the grain portion in the film was 99%, the width of the grain boundary layer was small,
As the particle size of the underlayer increases, the standard deviation / average particle size also increases. As a result, the particle size of the magnetic film also increases, and
/ N decreased.

No. 7 in Table 4 is also a comparative example.
Contrary to o.1, when the amount of Cr in the film is 63% by weight, the width of the grain boundary layer becomes large and the particle size of the underlayer becomes extremely small, so that the magnetic film can reflect the particle size of the underlayer. However, as a result, it became difficult to control the particle size of the magnetic film, and the S / N ratio was lowered.

No. 12 in Table 4 is also a comparative example, in which the component mixed with Cr-20Ti was SiO ₂ + TiO ₂ . Cr or Cr in the particle portion of the underlayer
In the case where the amount of the constituent particles of Ti is 65 to 98% by weight (Table 4, No. 2 to 6, No. 8 to 11), the S / N ratio is 25 or more, and the composition range in which the characteristics can be obtained. It is desirable that the target for obtaining the above film also has a Cr or Cr alloy content of 65 to 98% by weight.

In this embodiment, Cr and Na ₂ O—S
iO ₂ -CaO based glass, Cr-20Ti and SiO ₂ + T
It is shown for iO ₂ but, Cr or Cr-20Ti
The composition ratio of Cr-Ti is changed instead of
Alternatively, a metal or an alloy thereof having a body-centered cubic structure can expect the same effect.

The same effect can be expected by using an oxide, nitride or boride of Group IV of the periodic table as a substitute for Na ₂ O—SiO ₂ —CaO glass or SiO ₂ + TiO _2. it can.

[0107]

According to the present invention, by growing a magnetic film on a base film having a small crystal grain size distribution, crystal grains of the magnetic film can be made finer and the crystal grain size distribution can be reduced. . Thus, a magnetic recording medium with low noise and reduced thermal fluctuation and thermal demagnetization can be realized.

Also, since the crystal orientation of the magnetic film can be controlled, a magnetic film having an orientation suitable for high-density recording can be obtained.

Further, since the distance between the crystal grains of the magnetic film can be controlled, the interaction between the crystal grains of the magnetic film can be reduced. As a result, a magnetic recording medium having low noise and fine magnetic domains is obtained, and high-density recording becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a TEM photograph showing a typical structure of a base film and a schematic diagram thereof.

FIG. 3 is a schematic perspective view showing a schematic structure of a magnetic recording device according to an embodiment of the present invention.

FIG. 4 is a schematic sectional view of a base film / magnetic film laminate according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Base film, 3 ... Magnetic film, 4 ... Protective film, 5 ...
Lubricating film, 6, 16 magnetic recording medium, 7 particles, 8 grain boundaries, 11 magnetic head, 12 magnetic head arm, 13
... voice coil motor, 14 ... drive unit (rotation), 15
... Drive unit (recording).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/851 G11B 5/851 H01F 10/28 H01F 10/28 (72) Inventor Hiroki Yamamoto Hitachi, Ibaraki 7-1-1, Omikacho Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Mitsutoshi Honda 7-1-1, Omikamachi, Hitachi City, Ibaraki Pref. Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Hirano Tatsumi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Yuzo Kozono 1-1, Omika-cho, Hitachi City, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72 ) Inventor Ken Takahashi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi, Ltd. 4K029 AA09 BA 24 BA46 BA48 BD11 CA05 DC04 DC05 DC09 DC15 DC16 5D006 BB01 BB07 CA01 CA05 EA03 FA09 5D112 AA03 AA05 BB05 BB06 BD01 BD04 FA04 FB02 5E049 AA04 AA09 BA06 DB04 DB12 DB20

Claims (16)

[Claims] 1. A substrate, at least one metal or alloy having a body-centered cubic structure formed on the substrate, and a periodic table I to
Particles of at least one of oxides, nitrides, and borides of group V; at least one of metals or alloys having a body-centered cubic structure constituting grain boundaries of the particles; A magnetic recording comprising: a base film made of at least one of group V oxides, nitrides, and borides; and a magnetic film formed directly or through another layer on the base film. Medium. 2. The magnetic recording medium according to claim 1, wherein the particles are crystalline, and the grain boundaries of the particles are amorphous. 3. The undercoating film comprises one or more metals or alloys having a body-centered cubic structure and an oxide of Group I to V of the periodic table,
Particles composed of one or more of nitrides and borides, and a grain boundary phase of the particles, wherein the particles are 65 to 98% by weight of a metal or alloy having a body-centered cubic structure. At least one of Group III oxides, nitrides and borides is 2 to 35% by weight; and the grain boundary phase is a metal or alloy having a body-centered cubic structure, and an oxide of Group IV to IV of the periodic table. 3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium comprises at least one of a nitride and a boride. 4. The magnetic recording medium according to claim 1, wherein said underlayer is made of Cr or a Cr-based alloy having a body-centered cubic structure. 5. The method according to claim 1, wherein the average particle diameter of the particles constituting the base film is 15
~ 3.5 nm, the standard deviation (σ) of the particle size is 25 times the average particle size.
% Or less, the minor axis / major axis of the particles is 0.7 to 1, the width of the grain boundary phase separating each particle is 0.1 to 2 nm, and the particles are regularly arranged on the substrate surface. The magnetic recording medium according to claim 1, wherein: 6. The magnetic recording medium according to claim 1, wherein the thickness of the underlayer is 5 to 100 nm. 7. The magnetic recording medium according to claim 1, wherein said magnetic film is made of a ferromagnetic thin film made of Co or a Co-based alloy. 8. The magnetic film mainly composed of Co, and Pt, C
8. The magnetic recording medium according to claim 1, comprising at least one of r, Ta, and Nb. 9. The magnetic film is mainly composed of Co, and is composed of Pt, C
The magnetic particles are composed of an alloy containing at least one of r, Ta, and Nb and at least one of oxides, nitrides, and borides of Groups I to V of the periodic table, and the magnetic particles are partitioned by an amorphous grain boundary phase. The magnetic recording medium according to any one of claims 1 to 8, wherein 10. The crystal grains constituting the magnetic film have an average particle diameter of 15 to 3.5 nm, the standard deviation σ of the crystal particle diameter is 25% or less of the average particle diameter, and the minor axis / major axis of the particles is 10. The magnetic recording medium according to claim 7, 8 or 9, wherein the ratio is from 0.7 to 1. 11. A target made of one of a metal or an alloy having a body-centered cubic structure and a target made of one of an oxide, a nitride, and a boride of Groups I to V of the periodic table on a substrate. A method for manufacturing a magnetic recording medium, comprising: forming a base film by sputtering, and forming a magnetic film by growing magnetic particles on the base film. 12. A metal or alloy having a body-centered cubic structure, and oxides, nitrides, and oxides of Groups I to V of the periodic table on a substrate.
Using a target made of a mixed sintered body containing at least one boride, forming a base film by a sputtering method, and forming a magnetic film by growing magnetic particles on the base film. Manufacturing method of recording medium. 13. An amount of at least one metal or alloy having a body-centered cubic structure of 65 to 98% by weight, and an amount of at least one of oxides, nitrides and borides of Groups I to V of the periodic table of 35 to 2%. A target for forming a base film, wherein the target is mixed and sintered by weight. 14. Co or one or more of Co-based alloys,
A melt or sintered body mixed with the film to be formed in an amount of 65 to 98% by weight; and a melt or sintered body of at least one of oxides, nitrides and borides of Groups I to V of the periodic table. A target for forming a magnetic film, comprising: 15. A magnetic recording apparatus comprising: a drive mechanism for rotatingly driving a magnetic recording medium; and a magnetic head for performing recording and reproduction on the recording medium, wherein the magnetic recording medium has a body-centered cubic structure formed on a substrate. At least one metal or alloy of the periodic table I-
Particles composed of at least one of oxides, nitrides, and borides of Group V, at least one metal or alloy having a body-centered cubic structure constituting a grain boundary phase of the particles, and Periodic Tables I to I Magnetic recording characterized in that a base film containing at least one of oxides, nitrides and borides of group V and a magnetic film formed on the base film directly or via another layer. apparatus. 16. The magnetic recording medium according to claim 15, wherein the magnetic recording medium is formed by growing a magnetic film directly on a base film or via another layer, and has a surface recording density of at least 20 Gb / in ² . Magnetic recording device.