JP2001006165A - Manufacture for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make crystal particles fine and suppress generation of noises by forming an inorganic compound thin film by ECR sputtering using microwaves. SOLUTION: An inorganic compound thin film 2 is formed on a glass substrate 1 by ECR sputtering. A surface of the obtained inorganic compound thin film 2 is an aggregation of crystal particles having a regular hexagonal honeycomb structure and arranged regularly in two dimensions. In a lattice structure of the inorganic compound thin film, cobalt oxide becomes crystalline and silicon oxide is rendered amorphous. A lattice constant is made nearly equal to a value of Co, and can be controlled by a film form condition and further by adding a metal of a different ion radius to Cod. The number of crystal particles present in the periphery of the crystal particle changes depending on a crystal interval. A solvent substance present between the crystal particles has an important role to provide a structure with a regularity. Using the ECR sputtering can greatly improve the regularity of the structure of the inorganic compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium for storing a large amount of information quickly and accurately, and more particularly to a magnetic recording medium for a magnetic disk having high performance and high reliability. And a method for manufacturing a disk for a magnetic disk.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable progress in the advanced information society, and multimedia in which various forms of information are integrated has rapidly spread. One of the information recording devices that support this is a magnetic disk device. At present, the magnetic disk drive is being downsized while improving the recording density. At the same time, the cost of disk devices has been rapidly reduced. By the way, in order to realize the high density of the magnetic disk, 1) shorten the distance between the disk and the magnetic head, 2) increase the coercive force of the medium,
3) It is an essential technology to devise a signal processing method.

[0003] Above all, in a magnetic recording medium, an increase in coercive force is indispensable in order to realize high-density recording. In addition, in order to achieve a recording density exceeding ²⁰ Gbit / inch ² , the unit in which magnetization reversal occurs must be reduced. For that purpose, it is necessary to reduce the size of the magnetic particles. Further, it has become important to reduce the size distribution of the magnetic particles while minimizing the size distribution of the magnetic particles from the viewpoint of thermal fluctuation. As a method for realizing these, it has been proposed to provide a seed thin film under the magnetic film. One example is USP-4652499.

[0004]

In the above prior art,
There is a limit to the control of the crystal grain size of the magnetic film for information recording.Although the particle size distribution is small even in the magnetic film formed on the seed layer, it is difficult to achieve recording density exceeding ²⁰ Gbit / inch ² Fluctuation could not be sufficiently suppressed.
In order to realize this recording density, it is necessary to further suppress the distribution of fine particles and coarse particles. When recording information (when reversing the magnetization), these particles are affected by the stray magnetic field from surrounding magnetic particles, and conversely, large particles interact with each other.
When performing ultra-high density recording exceeding Gbit / inch ² , stable recording may not be performed.

Therefore, a first object of the present invention is to provide a high-performance magnetic recording medium with reduced noise generation by reducing the crystal grain size 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 suppressing dispersion of crystal grain size. 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. Further, a fourth object of the present invention is to provide a high-density magnetic recording medium because the unit of magnetization reversal at the time of recording or erasing can be reduced by reducing magnetic interaction between magnetic particles. . From the above, 20Gbit / inc
An ultra-high density magnetic recording medium exceeding h ² can be provided.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to deposit at least one oxide selected from cobalt oxide, chromium oxide, iron oxide or nickel oxide as crystal grains, and form silicon oxide, aluminum oxide, ECR using microwaves to produce an inorganic compound having a structure in which at least one oxide selected from titanium, tantalum oxide or zinc oxide is present as a crystal grain boundary phase so as to surround the crystal grains. By performing the sputtering method, the obtained inorganic compound and the crystal particles in the thin film have a hexagonal shape, the aggregate has a honeycomb structure, and the particles are regularly and two-dimensionally formed. It can be realized by forming an aligned inorganic compound and a thin film thereof. In the inorganic compound or its thin film produced by this method, the crystal particles precipitated in the inorganic compound are X-ray crystalline, and the solvent substance present at the grain boundary of the crystal particles is X-ray crystalline. It is amorphous.

[0007] In the structure of the inorganic compound and its thin film produced by the ECR sputtering method, the distribution of the crystal grain size is such that the statistical standard deviation: σ is 10% or less of the grain size, and The regularity of the structure is very high, such as a normal distribution. As described above, the use of the ECR sputtering method is characterized in that the regularity of the structure of the obtained material can be controlled with high accuracy. And
Even if an inorganic compound produced by excitation by the ECR method is formed into a thin film by the ECR sputtering method, the structure and the morphology of the thin film are reduced while maintaining the structure and morphology, and the structure in the thickness direction of the thin film is a columnar structure. preferable.

Considering that this thin film is used as a base film when producing a magnetic film for a magnetic disk, the film thickness is 10
Most preferably, it is not less than nm and not more than 100 nm. In particular, E
When the CR sputtering method is used, a thin film having regularity can be obtained with high accuracy even in a region where the film thickness is small. In addition, this material
The inorganic compound and the crystal particles precipitated in the thin film thereof can be crystallized. The crystal orientation of the inorganic compound thin film and the lattice spacing of the crystal particles can be controlled such that another thin film is epitaxially grown on the crystal particles. Here, the distance between the crystal grains of this thin film (grain boundary distance) is 0.5 nm or more and 2 nm or less,
Can be arbitrarily controlled. In order to control at least one parameter selected from the structure, orientation, and crystal grain size of the inorganic compound and its thin film, selection of the concentration (composition) of the substance forming the crystal grain, the compound constituting the material , A manufacturing method, a manufacturing condition, and the like. Of course, this material may be formed into a plate shape and used as a substrate. In this case, the crystal particles precipitated in the inorganic compound have a columnar structure in the thickness direction of the plate,
Needless to say, the crystal grains have a hexagonal shape, and the crystal grains have a honeycomb structure in which the crystal grains are regularly arranged two-dimensionally.

By the way, when a thin film of an inorganic compound produced by the ECR sputtering method is formed on a substrate, particles grow in a direction perpendicular to the substrate on which the crystal grains in the obtained thin film are formed, and the structure of the thin film is changed. It is preferable to have a columnar structure and have a crystal orientation in a certain direction.

By the way, it is most preferable to apply the inorganic compound and its thin film to a magnetic disk. The magnetic disk has at least a circular disk substrate and a magnetic film for recording information, and at least one type selected from cobalt oxide, chromium oxide, iron oxide or nickel oxide is formed on the circular disk substrate. The oxide was present as crystal grains, and at least one oxide selected from silicon oxide, aluminum oxide, titanium oxide, tantalum oxide or zinc oxide was precipitated at the crystal grain boundaries so as to surround the crystal grains. After forming an inorganic compound having a structure and a thin film thereof, a magnetic film is formed.
The structure and texture of the inorganic compound and the thin film produced in this manner are such that the shape of the crystal particles is hexagonal and the particles have a honeycomb structure in which the particles are regularly arranged two-dimensionally. Most preferably, after the compound is thinned and formed on a circular disk substrate, a magnetic film for magnetic recording is epitaxially grown from crystal grains of the inorganic compound.

Here, the particles precipitated in the inorganic compound thin film are X-ray crystalline, the compound in the grain boundary phase is X-ray amorphous, and the precipitated crystal particles have a certain orientation. Most preferably, the crystal structure of the particles is the same as or similar to the crystal structure or crystal plane spacing of the magnetic recording medium. Further, it is preferable that the precipitated particles of the inorganic compound thin film are crystalline in X-ray, and that the crystal orientation of the crystal particles is positively controlled in a desired direction. In this case, the precipitated particles of the inorganic compound thin film produced by this ECR sputtering method are X-ray crystalline, and the orientation of the crystal orientation of the crystal particles is determined by the crystal structure of the thin film epitaxially grown on the crystal particles. It is most preferable to control them together.

The use of the ECR method is advantageous because it has a honeycomb structure in which hexagonal crystal grains are regularly arranged two-dimensionally, and an amorphous material exists so as to surround the crystal grains. EC in the production of
By performing the production using the R method, it is possible to control the shape, arrangement state and orientation of the crystal grains with high precision, and as a result, the crystal grains precipitated around one crystal grain can be controlled. Focusing on the number, it is 5.8 or more and 6.2 or less.
Then, at least a magnetic disk having an inorganic compound thin film and a magnetic film for recording information and a protective film for protecting the thin film on a circular disk substrate in this order, the inorganic compound prepared by the ECR sputtering method above. A magnetic film is epitaxially grown from the crystal grains in the thin film of (1). As a result, the crystal grains of the inorganic compound thin film control the crystal growth of the magnetic recording medium, and at the same time, the crystal grains of the inorganic compound thin film and their surroundings. The structure of the magnetic film can be controlled by the presence of the amorphous particles. This is because the growth mechanism of the thin film is different between the crystal grains and the amorphous grains, so that the crystal structure and texture of the magnetic film can be suppressed.

In a magnetic disk having a thin film of an inorganic compound, a magnetic film for recording information and a protective film for protecting the thin film on a circular disk substrate, in particular, the thin film of the inorganic compound is formed on the substrate by ECR sputtering. By forming the magnetic film by epitaxial growth from the crystal grains of the inorganic compound thin film after formation, it is effective to make the crystal grains of the magnetic film equal in size to the crystal grains of the inorganic compound thin film. Here, again, the inorganic compound thin film produced by the ECR sputtering method applied to the magnetic disk is a material equivalent to the inorganic compound produced by the previous ECR sputtering method and the thin film, and the inorganic compound thin film is formed on the inorganic compound thin film. This means that the magnetic film has been epitaxially grown. Here, that the crystal structure of the inorganic compound film produced by the ECR sputtering method is similar to the crystal structure of the magnetic film means that the crystal forms of the crystal grains precipitated by the inorganic compound produced by the ECR sputtering method and the crystal form of the magnetic film. (E.g., crystal structure, crystal shape, crystal size, etc.), and the difference between the lattice constant of the crystal particles of the inorganic compound thin film prepared by ECR sputtering and the lattice constant of the magnetic film is within ± 10%. There is a need. Thereby, when the magnetic film is epitaxially grown from the crystal grains of the inorganic compound film, the consistency of the crystal lattice can be ensured. Of course, the difference in lattice spacing is ±
In the case of 10% or more, it goes without saying that one or more layers for adjusting the lattice spacing may be provided between the inorganic compound film and the magnetic film.

By the way, the ECR having the honeycomb structure described above
A material having the same structure as the inorganic compound manufactured by the sputtering method may be used as the substrate. In a magnetic disk having at least a circular substrate, a magnetic film for recording information and a protective film for protecting the same, the material of the disk substrate is selected from cobalt oxide, chromium oxide, iron oxide or nickel oxide. Silicon oxide so as to surround at least one type of oxide crystal particles,
It is an inorganic compound in which at least one oxide selected from aluminum oxide, titanium oxide, tantalum oxide or zinc oxide is present at the grain boundaries of the crystal grains, and the crystal grains of the inorganic compound are subjected to the ECR method. Thus, the crystal grains are regularly arranged two-dimensionally, and the shape of the crystal grains has a honeycomb structure, and a substrate for a disk may be manufactured using this material. In this case as well, excitation using the ECR method for material synthesis has a large effect on particle size and particle shape. In other words, the crystal grains are arranged two-dimensionally and regularly, and the number of crystal grains surrounding the crystal grains of the inorganic compound having a honeycomb structure is 5.8 or more and 6.2 or less. Again,
As the structure of the material, the crystal grains are arranged two-dimensionally and regularly by being manufactured by the ECR method, and the shape of the crystal grains has a honeycomb structure.

Most preferably, the difference between the lattice constant of the inorganic compound and the magnetic film formed on the substrate is ± 10% or less. Conversely, crystal grains produced by the ECR method are regularly arranged two-dimensionally, and the shape of the crystal grains is different from the lattice constant of the inorganic film having a honeycomb structure and the magnetic film formed on the substrate. However, if the ratio is ± 10% or more,
By providing a thin film layer between the inorganic compound substrate and the magnetic film for alleviating the difference in lattice constant between the two layers, which is within ± 10%, the magnetic recording medium can be made to have a crystal in the inorganic compound thin film The epitaxial growth may be promoted from the particle layer.

In a substrate prepared using an inorganic compound constituting an inorganic compound, precipitated crystal grains are X-ray crystalline and the material of the grain boundary phase is X-ray amorphous. Needless to say. In addition, the crystal structure of the precipitated particles must be the same as or similar to the crystal structure of the magnetic crystal particles of the magnetic recording medium formed on the substrate. Here, the expression that the crystal shapes are similar means that the crystal structures are the same and the difference in lattice spacing is within ± 10%.

As a magnetic film used for recording on a magnetic disk, a ferromagnetic thin film of an alloy mainly containing Co and containing at least two elements selected from Cr, Pt, Ta, Nb, Ti and Si is used. Is most preferred. This ferromagnetic thin film is a thin film of an alloy mainly composed of Co and containing at least two kinds of elements selected from Cr, Pt, Ta, Nb, Ti, and Si. Is crystalline. The crystal grains are a Co alloy, which may be epitaxially grown from the inorganic compound produced by the ECR method or the crystal phase of the thin film thereof. This alloy system is a thin film of a magnetic alloy mainly composed of Co and containing at least two kinds of elements selected from Cr, Pt, Ta, Nb, Ti, and Si. At least one element selected from Nb, Ti, and Si is segregated near or at the grain boundaries of Co.

Apart from this material system, the structure of the magnetic film is different, but the magnetic recording medium is composed of two phases, a crystalline phase and an amorphous phase, and the crystalline phase is mainly composed of Co, which contains Nd, Pr, Y, La, Sm, G
d, Tb, Dy, Ho, Pt, a phase containing at least one element selected from Pd, silicon oxide as an amorphous phase,
A magnetic film having a structure in which at least one compound phase selected from zinc oxide, tantalum oxide, and aluminum oxide exists so as to surround the crystal grains may be used. In forming this magnetic film, Co particles and oxides corresponding to the amorphous phase may be deposited and grown on the inorganic compound or the crystalline layer of the thin film prepared by the ECR method. As a result, both the crystal grain size of the inorganic compound and the size of the magnetic film can be made equal. Conversely, both of the above two types of magnetic materials govern the crystal grain size and size distribution because they depend on the structure or texture of the inorganic compound or its thin film. It can be realized by epitaxially growing an inorganic compound produced by the ECR method or crystal grains of a thin film thereof. EC the inorganic compound thin film
By manufacturing by the R sputtering method, it becomes possible to control the crystal grain size and its distribution to a certain value or less.

The above-described inorganic compound or its thin film was used as a substrate or a base film, and a magnetic film and a protective film were formed on the inorganic compound to form a disk. This magnetic disk is used in a magnetic disk device including at least a magnetic disk, a magnetic head, and an electric circuit. Then, information is recorded, reproduced or erased using this magnetic disk device. That is, a magnetic disk device is configured by combining a magnetic disk and a magnetic disk on which such a magnetic recording medium is formed with a magnetic head and an electric circuit. This device records various information such as images, code data, and audio,
Play or erase.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described with reference to embodiments.

Embodiment 1 This embodiment is directed to a case of an inorganic compound thin film formed by an ECR sputtering method. FIG. 1 is a schematic diagram showing a cross-sectional structure of the manufactured sample. An inorganic compound thin film (2) was formed on a glass substrate (1) by ECR sputtering. Pure Ar was used as a discharge gas for a target obtained by mixing and sintering CoO and SiO ₂ at a ratio of 2: 1. The pressure during sputtering is 3 mTorr, and the input microwave power is 1 kW. Further, an RF bias of 500 W was applied to the target. The thickness of the prepared thin film is 30 nm. FIG. 2 shows a schematic diagram of the result of observation of the surface of the obtained inorganic compound thin film (2) by TEM. From this figure, it can be seen that this thin film is an aggregate of crystal grains in which crystal grains having a regular hexagonal honeycomb structure of 10 nm are regularly arranged two-dimensionally.

The distance between the crystal grains was 0.5 to 1.0 nm. This value, the composition of the target (such as the ratio of CoO and SiO ₂₎
, The desired value can be easily and arbitrarily selected. By the way, the maximum grain boundary distance is 2n
It is difficult to make it more than m. The crystal grains are oxides of cobalt, and silicon oxide is present at the crystal grain boundaries.

From observation of the lattice image of the inorganic compound thin film, it was found that the cobalt oxide was crystalline and the silicon oxide was amorphous. When the lattice constant was determined, the value was almost equal to the value of Co. Lattice constants, film formation conditions, further, CoO different metals ionic radius (for example, chromium,
It can be controlled by adding iron or nickel). Alternatively, the same applies to the case where oxides of these metals are added.

When the cross section of this thin film was observed,
A columnar structure was observed in a direction perpendicular to the substrate. It was found that the columnar structure grew without abnormal growth such as an increase in crystal grain size in the middle.

Next, the number of crystal particles existing around one crystal particle was analyzed using the results of TEM observation of the surface of the inorganic compound thin film. First, when the crystal particle size was determined, the average particle size was 10 nm. The particle size distribution is a normal distribution, and the standard deviation is 0.6n
m or less.

Next, the number of crystal particles existing around one crystal particle was determined. When 280 crystal grains were examined, the average was 6.02. This indicates that hexagonal crystal grains of uniform size are regularly arranged two-dimensionally (honeycomb structure). 1
The number of crystal grains existing around one crystal grain changes depending on the crystal grain spacing. That is, when the SiO ₂ concentration of the solvent is reduced, the particle interval becomes narrower (the crystal particles come closer to each other). At the same time, disturbances in the particle shape were observed. Regarding the number of crystal grains existing around one crystal grain, there were about seven grains, and conversely, there were about four to five grains, and the variation became large. In addition, the two-dimensional arrangement was disturbed, and the honeycomb structure was broken.

As described above, the solvent substance existing between the crystal grains has an important role of imparting regularity to the structure. This film was produced by a method other than the ECR sputtering method. Analysis of the structure of the inorganic compound thin film produced by the usual magnetron sputtering method showed that the average particle size was 10 nm, but the particle size distribution was a normal distribution,
When the standard deviation is obtained, the value of σ is 1.2 nm, which indicates that the distribution is large. Further, when the number of crystal particles existing around one crystal particle was determined, and the number of crystal particles was examined on 280 crystal particles, the average was 6.3, indicating that the regularity was slightly lowered. Thus, it can be seen that the use of the ECR sputtering method can greatly improve the regularity of the structure of the inorganic compound.

Finally, the crystal structure of the inorganic compound thin film was analyzed by an X-ray diffraction method. Figure obtained profile
See Figure 3. According to this, CoO (220) around 2θ = 62.5 °
Was observed. No other peak was observed. In this structure, an inorganic compound film having a desired structure can be obtained by controlling film forming conditions and composition.
That is, the orientation can be controlled. Furthermore, μ-EDX
Analysis of the grain boundaries and the crystal grains, the crystal particles are oxides of Co, are you present in the grain boundaries is SiO ₂
Met.

In the above experiment, the target was CoO
And it was used by sintering a mixture of SiO _2. A film obtained by sintering each of these compounds alone may be used as a target to form a film by dual simultaneous sputtering, and does not depend on the film forming method or the type of target. What is important here is to precisely control the energy of sputtered particles by using an ECR sputtering method using microwaves. The film thickness is 5n
Conversely, even at a thickness of about m, no change depending on the film thickness was observed in the structure and structure of the surface and cross section of the obtained film even when the film thickness was increased to 100 nm, the particle size, the size distribution, and the like. Furthermore, no initial growth layer was observed at the beginning of the film formation. When the film thickness is 5 nm or less, it is difficult to stably produce the film due to the convenience of a film forming apparatus, and when the film thickness is 100 nm or more, it takes a long time to form a film, so that there is a limitation in manufacturing.

Embodiment 2 In this embodiment, an inorganic compound thin film manufactured by using the ECR sputtering method is used as a base film,
This is an example of a magnetic disk on which a Co-based alloy magnetic film is epitaxially grown. FIG. 4 shows a sectional structure of the disk. As the substrate (1), a disk was a glass disk having a diameter of 2.5 mm. The glass substrate used here is only one example, and any size disk substrate can be used,
Use of an Al or Al alloy substrate does not affect the effects of the present invention. An inorganic compound thin film (2) was formed thereon by ECR sputtering. Pure Ar was used as a discharge gas for a target obtained by mixing and sintering CoO and SiO ₂ at a ratio of 2: 1. The pressure during sputtering is 3 mTorr, and the input microwave power is 1 kW. Further, an RF bias of 500 W was applied to the target. The thickness of the prepared thin film is 30 nm.

When the surface of the obtained inorganic compound thin film (2) was observed by TEM, the thin film was an aggregate of particles in which crystal particles having a regular hexagonal honeycomb structure of 10 nm were regularly arranged in two dimensions. You can see that. The distance between the crystal grains was 0.6 nm. This value depends on the composition of the target (CoO
The desired value can be selected by changing the ratio of SiO ₂ to SiO ₂ . The crystal grains are oxides of cobalt, and silicon oxide is present at the crystal grain boundaries. From the lattice image observation, the cobalt oxide is crystalline,
The silicon oxide was found to be amorphous. When the lattice constant was determined, it was almost equal to the value of Co. The lattice constant can be controlled by film formation conditions and further by adding a metal (eg, chromium, iron, nickel, or the like) having a different ionic radius to CoO. Alternatively, the same applies to the case where oxides of these metals are added.

When the cross section of this thin film was observed,
A columnar structure was observed in a direction perpendicular to the substrate. It was found that the columnar structure grew without enlarging the crystal grains in the middle. Next, the TEM of the surface of the inorganic compound thin film
Using the observation results, the number of crystal particles existing around a certain crystal particle was analyzed. First, when the crystal particle size was determined, the average particle size was 10 nm. The particle size distribution has a normal distribution, and when the standard deviation is obtained, σ
Was 0.6 nm or less. Next, the number of crystal particles existing around one crystal particle was determined. When 280 crystal grains were examined, it was 6.02. This indicates that hexagonal crystal grains of uniform size are regularly arranged two-dimensionally (honeycomb structure).
The number of crystal grains existing around one crystal grain varies depending on the crystal grain spacing in addition to the grain size distribution and grain shape.

On this, Co ₆₉ Cr ₁₉ Pt was used as a magnetic film (3).
_Twelve films were formed to a thickness of 15 nm by DC sputtering. The substrate was heated to 300 ° C. during the production of the magnetic film. C for target
An o-Cr-Pt alloy was used, and pure Ar was used as a discharge gas. The pressure during sputtering is 3 mTorr. Input DC power is
1kW / 150mmφ. Finally, a C film is formed as a protective film (4).
It was formed to a thickness of 5 nm. The sputtering conditions are as follows: input DC power density is 1 kW / 150 mmφ, and discharge gas pressure is 5 mTorr.
Here, Ar is used as the sputtering gas, but it goes without saying that a gas containing nitrogen may be used. this is,
Since the particles become finer, the resulting film becomes denser and the protection performance can be improved. As for the film quality of this film, in addition to such a sputtering method, since the properties of the obtained film greatly depend on the apparatus, these conditions and methods are not absolute. In addition, when the ECR sputtering method is used as the manufacturing method, the protection performance can be improved, and at the same time, the damage to the magnetic film and the like at the time of film formation can be further reduced.

Next, when the structure of this magnetic film was examined by TEM observation, it had a honeycomb structure reflecting the structure and shape of the inorganic compound thin film. The average particle size of the particles determined from observation of the plane with an electron microscope is 10 nm,
When the particle size distribution was determined, the standard deviation: σ was 0.8 nm or less. Thus, it can be seen that the particles of the magnetic film are finer and have a smaller size distribution, and have the same form as the inorganic compound thin film. Next, the number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure).

Observation of the cross-sectional structure of this film by TEM revealed that a lattice connection was found between the inorganic compound thin film and the magnetic film layer, and that the magnetic film was epitaxially grown from the inorganic compound thin film. . In addition, it was found that the growth mechanism of the magnetic film was different between the crystal phase and the grain boundary phase, and had different metal structures. In particular, a good columnar structure was grown from the crystal grains of the inorganic compound, but no clear structure was observed from the grain boundary phase, and the crystal was an aggregate of polycrystals. Such a tissue is known to exhibit non-magnetic behavior. X-rays show a weak peak near 2θ = 72.5 ° in addition to the peak near 2θ = 62.5 °,
Considering the observation results, this peak is Co (11.0)
Are strongly oriented.

The magnetic properties of the magnetic film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10 ^-16 emu,
S is an index of the squareness of hysteresis in the MH loop
Was 0.8 and S † was 0.86, indicating good magnetic properties. As described above, the index indicating the squareness is large (close to the square shape) because the growth mechanism of the magnetic film is different reflecting the grain boundary layer of the inorganic compound thin film, and the interaction between the magnetic crystal grains is different. Is reduced.

Next, a lubricant was applied to the medium surface of a magnetic disk using a magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated. For recording, a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used as the recording head. Reproduction was performed by a head having a giant magnetoresistance effect. The distance between the head surface and the magnetic film is 20nm
It is. When a signal corresponding to 40 Gbit / inch ² was recorded on this disk and the S / N of the disk was evaluated, a reproduction output of 32 dB was obtained. Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was found to be about three particles from two, which was sufficiently smaller than that of a normal magnetic disk. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium.
In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the distribution of the crystal grain size of the magnetic film is small. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

Here, an example in which a thin film for controlling a crystalline lattice constant is formed on a glass substrate has been described, but a substrate is manufactured using the material on which the thin film is formed, and a magnetic film is formed thereon. It goes without saying that it may be formed. In this example, an example using cobalt oxide as a solute substance was described.
The same effect was obtained by using chromium oxide, iron oxide or nickel oxide. Furthermore, although silicon oxide was used as the oxide of the solvent, similar results were obtained by using aluminum oxide, titanium oxide, tantalum oxide, or zinc oxide. Here, when a mixture of silicon oxide and zinc oxide is used as a solvent molecule, the distance between crystal grains can be controlled by the mixture ratio.

Embodiment 3 In this embodiment, the lattice constant of the crystal grains of the inorganic compound thin film formed on the substrate is different from the lattice constant of the magnetic film by 10% or more. FIG. 5 shows a schematic diagram of a cross-sectional structure of the manufactured magnetic disk. First, a 2.5 ″ diameter glass substrate was used as a substrate for a magnetic disk. The glass substrate used here is only one example, and a disk substrate of any size can be used. Does not affect the effects of the present invention.CoO and ZnO were mixed on the substrate (1) at a ratio of 3: 1 as the inorganic compound thin film (2) under the same conditions as in the first embodiment. Using the target as a target and sputtering
It was formed to a thickness of nm. This film thickness is such that it does not peel off from the substrate in consideration of the internal stress of the entire magnetic recording medium. Observation of the surface of the inorganic compound thin film (2) by TEM revealed that it was an aggregate of 10 nm regular hexagonal crystal particles.

Next, the number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure).

Incidentally, the lattice constant of CoO of the crystal grains was 20% larger than that of the magnetic film. Although the crystal grains are cobalt oxide, which is the same as in Example 1, the lattice constant can be changed in addition to the crystal grain size. The μ-EDX analysis revealed that this was because the solvent substance was dissolved in the crystal particles as the solute substance.

Therefore, as a material having an intermediate lattice constant between the inorganic compound thin film (2) and the magnetic film, a Cr ₈₅ Ti ₁₅ alloy thin film was formed prior to the production of the magnetic film. This material is Ti
By controlling the concentration, the lattice constant can be arbitrarily selected from the lattice constant of Cr.
The difference in lattice constant from (3) can be suppressed within 10%. As this lattice constant control thin film (5), a Cr ₈₅ Ti ₁₅ alloy thin film was formed to a thickness of 50 nm. Cr-Ti alloy for the target,
Pure Ar was used as the discharge gas. The pressure during sputtering is 3 mTorr. The input DC power is 1kW / 150mmφ. On this, a Co ₆₉ Cr ₁₉ Pt ₁₂ film was formed as a magnetic film (3) by 12n.
It was formed to have a thickness of m. A Co-Cr-Pt alloy was used for the target, and pure Ar was used for the discharge gas. The pressure during sputtering is 3 mTorr. The input DC power is 1kW / 150mmφ.
Finally, a C film was formed to a thickness of 5 nm as a protective film (4). The sputtering conditions are as follows: Input DC power density is 1kW / 150mm
φ, discharge gas pressure is 5 mTorr. Here, Ar is used as the sputtering gas, but it goes without saying that a gas containing nitrogen may be used. This is because the particles become finer, and the resulting film becomes denser, and the protective performance can be improved. As for the film quality of this film, in addition to such a sputtering method, since the properties of the obtained film greatly depend on the apparatus, these conditions and methods are not absolute.

Next, FIG. 5 shows the result of examining the structure of this magnetic film by the X-ray diffraction method. As shown in this figure, Co
It can be seen that (11.0) is strongly oriented. From the observation of the medium surface, the average particle diameter of the magnetic film was 10 nm, which was almost the same as the value of the inorganic compound thin film. When the particle size distribution of the particles was determined, it was 0.8 nm or less in σ. in this way,
It can be seen that the crystal grains of the magnetic film are miniaturized and the particle size distribution is small. In addition, cross-sectional observation revealed that the inorganic compound thin film and the magnetic film were epitaxially grown. The structure also had a good columnar structure, and it was found that the crystal grain size did not change from the substrate surface to the medium surface.

The magnetic properties of the magnetic film were measured. The obtained magnetic properties are as follows: coercive force is 3.0 kOe, Isv is 2.5 × 10 ^-16 emu,
S is an index of the squareness of hysteresis in the MH loop
Was 0.81 and S † was 0.85, showing good magnetic properties.

Next, a lubricant was applied to the medium surface of a magnetic disk using a magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated. The configuration of the magnetic disk drive is the same as that of the second embodiment, and is schematically shown in FIG. As the magnetic head (53), a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used for recording. Reproduction was performed by a head having a giant magnetoresistance effect. The magnetic head is controlled by a drive system (54).
The magnetic disk (51) was rotated by the spindle (52), and the distance between the head surface and the magnetic film was kept at 15 nm. On this disc
Record a signal equivalent to 40 Gbit / inch ² and S / N of the disc
As a result, a reproduction output of 32 dB was obtained. Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was found that the size was about 3 particles from 2 and sufficiently small. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium.
In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the distribution of the crystal grain size of the magnetic film is small. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

Here, an example in which a thin film for controlling a crystalline lattice constant is formed on a glass substrate has been described, but a substrate is manufactured using the material on which the thin film is formed, and a magnetic film is formed thereon. It goes without saying that it may be formed. In this example, an example in which cobalt oxide was used as crystal grains was described. However, the same effect was obtained by using iron oxide or nickel oxide in addition to cobalt oxide. further,
Although silicon oxide was used as the oxide present so as to surround the crystal grains, the same effect was obtained by using aluminum oxide, titanium oxide, tantalum oxide or zinc oxide.

Fourth Embodiment In this embodiment, a Co—SiO ₂ granular magnetic film is used as a magnetic film for magnetic recording. The structure of the manufactured magnetic disk is the same as that of the second embodiment, and a schematic diagram of the cross-sectional structure is as shown in FIG.

A 2.5 ″ diameter glass substrate was used as a substrate (1) for a magnetic disk, on which an inorganic compound film (2) having a two-dimensionally ordered honeycomb structure was formed by ECR sputtering. The production conditions were the same as those in Embodiment 2. Subsequently, a Co—SiO ₂ based magnetic film having a granular structure was produced as a magnetic film (3) by ECR sputtering. SiO ₂ system mixture (mixing ratio: Co: Si
O ₂ = 1: 1) A target was used, and Ar was used as a discharge gas. The discharge gas pressure during sputtering is 3 mTorr and the input microwave power is 1 kW.
A bias is applied and the value is 500W. During film formation, the substrate was heated to 300 ° C. The thickness of the formed magnetic film is 10 nm.

The plane and cross section of this film were observed with a high-resolution transmission electron microscope. As a result, the inorganic compound thin film
Co of the magnetic film was epitaxially grown from the crystal phase of (2), and SiO ₂ was grown from the amorphous phase (grain boundary phase) surrounding the crystal phase. The cross section is columnar structure, Co is SiO ₂
, The particles were separated from each other, and the magnetic interaction was greatly reduced. This is a structure of a magnetic film effective for high-density magnetic recording. The unevenness of the surface of the magnetic recording medium is 6 μm in the horizontal direction and 10 nm or less in the vertical direction.
(Below the lower limit of AFM measurement). This unevenness reflects the unevenness of the inorganic compound layer. Here, for the production of the magnetic film
ECR sputtering method was used, but Co-SiO ₂ mixture (or composite)
The magnetron sputtering method or the like may be used using the above target. However, in this case, the crystal grain shape is ECR
It may be slightly deteriorated compared to the case where the sputtering method is used.
On this magnetic film, the same protective film as in the first and second embodiments
(4) was produced by ECR sputtering. The protective film thickness is 2 nm. TEM observation of the surface of the magnetic recording medium after formation of the protective film revealed that the surface was the same as the surface of the magnetic film, and that the surface of the magnetic film was completely covered with the protective film.

The magnetic characteristics of the magnetic recording medium thus manufactured were measured. The obtained magnetic properties show that the coercive force is 4.0k
Oe, Isv is 2.5 × 10 ^-16 emu, S which is an index of the squareness of hysteresis in the MH loop is 0.85, S † is 0.90,
It had good magnetic properties. It can be seen that this is because the crystal grain size of the magnetic film is small and its variation is small, and the result reflects a reduction in magnetic interaction between crystal grains. In addition, since almost no fine crystal particles are present, it is understood that the medium is excellent in heat fluctuation. Further, the magnetic characteristics were compared with a sample in which a protective film was formed without using the ECR sputtering method of the present invention. The technique used is a magnetron type RF sputtering method. The magnetic properties of the magnetic film produced by this method had a coercive force reduced to 2.5 to 1.8 kOe. The coercive force had a large distribution on one magnetic disk. Thus, the ECR sputtering method can suppress damage to the magnetic film in addition to the coverage and the density of the film.

Next, a lubricant was applied to the medium surface of the magnetic disk using the magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the magnetic disk (51) were evaluated. The configuration of the magnetic disk drive is the same as that of the second embodiment, and is schematically shown in FIG. As the magnetic head (53), a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used for recording. Reproduction was performed by a head having a giant magnetoresistance effect. The magnetic head is controlled by a drive system (54). The magnetic disk is rotated by the spindle (52),
The distance between the head surface and the magnetic film is 15 nm. A signal equivalent to 40 Gbit / inch ² was recorded on this disc and the S /
When N was evaluated, a reproduction output of 32 dB was obtained.

Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was about 3 particles from 2 particles.
It turned out to be small enough. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the distribution of the crystal grain size of the magnetic film is small. When the error rate of this disk was measured, the value was 1 × 10 ⁻¹² or less when no signal processing was performed. Here, when the distance between the head and the surface of the magnetic recording medium was set to 15 nm, the head stably floated. However, when a magnetic disk having no inorganic compound layer produced by the ECR sputtering method was driven under the same conditions, a stable reproduction signal could not be obtained or a head crash occurred. The reason why a stable reproduction signal cannot be obtained is that the unevenness of the surface of the recording medium exceeds the range where the distance between the magnetic head and the medium can be controlled to be constant, and the distance between the head and the surface of the magnetic recording medium is not constant. Because.

Here, Co-SiO ₂ was used as the magnetic recording medium, but Pt, Pd, Gd, Sm, Pr, Nd, Tb, Dy, Ho,
It goes without saying that when the magnetic anisotropy is improved by adding an element such as Y or La, the performance is further improved.

Embodiment 5 In this embodiment, the lattice constant of the crystal phase in the inorganic compound thin film is controlled. A schematic diagram of the cross-sectional structure of the manufactured magnetic disk is the same as that of the second embodiment, and is as shown in FIG.

First, as a substrate for a magnetic disk, 2.
A glass substrate with a diameter of 5 ″ was used. The glass substrate used here is only one example, and the effect of the present invention can be obtained by using a disk substrate of any size or using an Al or Al alloy substrate. CoO on this substrate (1)
Inorganic compound thin film (2) was formed by simultaneous sputtering using a mixture of 3: 1 Fe ₂ O ₃ and sintered and a target of ZnO. The sputtering power was adjusted so that the film thickness was 30 nm and the mixture ratio of the two was 2: 1. The pressure during sputtering is 3 mTorr, and the discharge gas is pure Ar. Observation of the surface of the obtained inorganic compound thin film (2) by TEM showed that the surface was the same as in Example 1. This film is an aggregate in which crystal grains of 10 nm regular hexagonal honeycomb structure are regularly arranged. The distance between the crystal grains was 0.5 to 1.0 nm. The crystal grains had iron in the interstices of the lattice of the cobalt oxide. Further, silicon oxide was present at the crystal grain boundaries. When the lattice image was observed, the cobalt oxide was crystalline and the silicon oxide was amorphous.

Next, the number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure). When the lattice constant was determined, it was almost equal to that of CoO. It can be seen that the lattice constant can be controlled by adding iron oxide to the system of cobalt oxide and zinc oxide.

On this, Co ₆₉ Cr ₁₉ Pt was formed as a magnetic film (3).
_Twelve films were formed to a thickness of 12 nm. A Co-Cr-Pt alloy was used for the target, and pure Ar was used for the discharge gas. The pressure during sputtering is 3 mTorr. Input DC power is 1kW / 150mmφ
It is. During film formation, the substrate was heated to 300 ° C. Finally,
As the protective film (4), a C film was formed to a thickness of 5 nm. The sputtering conditions are as follows: input DC power density is 1 kW / 150 mmφ, and discharge gas pressure is 5 mTorr. Here, the sputtering gas is A
Although r was used, it goes without saying that a gas containing nitrogen may be used. This is because the particles obtained are finer and the resulting film is denser, and the protection performance can be improved. As for the film quality of this film, in addition to such a sputtering method, since the properties of the obtained film greatly depend on the apparatus, these conditions and methods are not absolute.

Next, when the structure of this magnetic film was examined by X-ray diffraction, it was found that Co (102) was strongly oriented. Here, the lattice constants of the inorganic compound thin film and the magnetic film were almost the same at 0.402 nm. The average particle diameter was 10 nm from the plane observation by an electron microscope, and the particle diameter distribution was determined. The standard deviation: σ was 2 nm or less. Thus, it can be seen that the particles of the magnetic film are finer and the size distribution is smaller. The number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure). Also, the cross-sectional observation shows that the inorganic compound thin film and the magnetic film are epitaxially grown and have the same size as the crystal phase which is a solute of the inorganic compound thin film. Further, it was found that the structure of the cross section was also a good columnar structure, and the crystal grain size did not change from the substrate surface to the medium surface.

The magnetic properties of the magnetic film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10 ^-16 emu,
S is an index of the squareness of hysteresis in the MH loop
Was 0.8 and S † was 0.86, indicating good magnetic properties.

Next, a lubricant was applied to the medium surface of a magnetic disk using a magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated. The same apparatus as that used in Embodiment 2 was used. For recording, a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used as the recording head. Reproduction was performed by a head having a giant magnetoresistance effect. The distance between the head surface and the magnetic film is 20 nm. When a signal corresponding to ²⁰ Gbit / inch ² was recorded on this disk and the S / N of the disk was evaluated, a reproduction output of 32 dB was obtained. Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was about three particles from two,
It turned out to be small enough. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the distribution of the crystal grain size of the magnetic film is small. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

Here, an example in which a thin film for controlling a crystalline lattice constant is formed on a glass substrate has been described. However, a substrate is manufactured using the material on which the thin film is formed, and a magnetic film is formed thereon. It goes without saying that it may be formed. Also, in this example, an example was described in which iron oxide was contained in cobalt oxide as a solute substance.However, the same effect was obtained even when chromium oxide or nickel oxide was used. The compound to be used, the compound to be added, and the amount of addition may be determined. Furthermore, although zinc oxide was used as the oxide of the solvent, similar results were obtained by using aluminum oxide, titanium oxide, tantalum oxide or silicon oxide.

Embodiment 6 In this embodiment, the spacing between crystal grains is controlled by controlling the material of the solvent phase in the inorganic compound thin film. An inorganic compound layer was formed to a thickness of 30 nm on a glass substrate by using a dual simultaneous sputtering method. For the target, a target obtained by sintering CoO as a solute substance, and ZnO to SiO ₂ as a solvent substance
Two targets mixed and sintered at a ratio of 3: 1 were used. The composition of the inorganic compound film can be controlled by electric power supplied to the dual target. Use pure Ar for discharge gas,
The pressure during sputtering was 3 mTorr. Input RF power is CoO
And the ratio of SiO ₂ -ZnO was adjusted to 2: 1. FIG. 2 is a schematic diagram showing the results of TEM observation of the surface of the obtained inorganic compound layer. From this figure, 10nm hexagonal crystal particles
It can be seen that the (honeycomb structure) is regularly arranged two-dimensionally. A grain boundary phase of about 1 nm was present around the crystal grains. Analysis of the crystal grains and the grain boundary phase by μ-EDX revealed that the crystal grains were oxides of cobalt, a solute substance, and that silicon oxide and zinc oxide as solvents were present at the grain boundaries. .

Next, the number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure).

Incidentally, the distance between crystal grains (grain boundary distance)
Can be changed by controlling the solute concentration (the solvent concentration may be relatively changed) and the composition of the solvent substance (here, the ratio between SiO ₂ and ZnO). For example, C
o As the oxide concentration was reduced, the distance between grain boundaries became shorter. The ratio of solvent: solute = 1: 5 was 0.5 nm.
When the solute concentration was lower than this, the grain boundaries became less clear. At the same time, the honeycomb structure collapsed. From this, it is understood that at least about 15% or more of the solvent substance is necessary to maintain the honeycomb structure. Conversely, when the concentration of the solvent substance was increased, the ratio of solvent: solute = 5: 1 became 3.0 nm.
When the solvent concentration is higher than this, the solvent substance does not exist between the crystal grains but precipitates in a shape close to a circle. Also in this case, the honeycomb structure collapses. In addition, when controlling the distance between crystal grains by changing the composition of the solvent substance, a difference in sputtering speed between materials being mixed is used, or a change in volume due to penetration of atoms having different ionic radii is used. The mechanism is different,
The resulting effect is the same.

Incidentally, it is important to control the distance between crystal grains from the following points. That is, the first embodiment
As shown in FIGS. 1 to 5, when a magnetic film is epitaxially grown on this inorganic compound film to form a magnetic recording medium,
It is important to reduce the magnetic interaction between the magnetic crystal grains. Controlling the distance between crystal grains can change the magnetic interaction. In particular, since the structure and structure of the formed magnetic particles are different between the crystal grains and the grain boundary phase, the magnetic properties of the magnetic particles are completely different. The magnetic particles on the crystal particles reflect the structure of the crystal particles in the inorganic compound layer and have good crystallinity, whereas the grain boundaries are in a random orientation and almost amorphous state. . Thus, it has been found that the magnetic properties of the magnetic film and the magnetic recording medium reflect the film structure of the magnetic film.

Normal hard magnetism is exhibited on the crystal grains, and it becomes almost non-magnetic in the grain boundary phase. Thus, the magnetic interaction could be easily controlled using a simple method. Since the degree of the interaction varies depending on the distance between the grain boundaries, it is important to control the distance between the grains.

Embodiment 7 This embodiment is directed to a case where a disk substrate manufactured by using the regularly arranged inorganic compound having a honeycomb structure of the present invention is used. FIG. 7 shows a schematic diagram of a cross-sectional structure of the manufactured magnetic disk. Here, a 2.5 ″ diameter glass substrate was molded as the magnetic disk substrate (1). The glass substrate used here is only one example, and the disk substrate of the present invention can be used regardless of the size of the disk substrate. It does not affect the effect.
It was fabricated using the ECR method in which O _{2 was} mixed with SiO ₂ and excited by microwaves. The cross section of the obtained substrate was observed by TEM. This substrate is an aggregate in which crystal grains having a regular hexagonal honeycomb structure of 10 nm are regularly arranged. The spacing between the crystal grains was 0.5-0.8 nm. The crystal grains are oxides of cobalt. Silicon oxide is present at the crystal grain boundaries. When the lattice image was observed, the cobalt oxide was crystalline and the silicon oxide was amorphous. Next, the number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, the result was 6.01, which was in good agreement with the value of the inorganic compound thin film of the first embodiment. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly arranged two-dimensionally continuously from the inorganic compound thin film layer.
(Honeycomb structure). When the lattice constant was determined, it was almost equal to that of Co of the magnetic particles of the magnetic recording medium.

On this, Co ₆₉ Cr ₁₉ Pt was formed as a magnetic film (3).
_Twelve films were formed to a thickness of 12 nm. A Co-Cr-Pt alloy was used for the target, and pure Ar was used for the discharge gas. The pressure during sputtering is 3 mTorr. Input DC power is 1kW / 150mmφ
It is. During film formation, the substrate was heated to 300 ° C. Finally,
As the protective film (4), a C film was formed to a thickness of 5 nm. The sputtering conditions are as follows: input DC power density is 1 kW / 150 mmφ, and discharge gas pressure is 5 mTorr. Here, the sputtering gas is A
Although r was used, it goes without saying that a gas containing nitrogen may be used. This is because the particles obtained are finer and the resulting film is denser, and the protection performance can be improved. As for the film quality of this film, in addition to such a sputtering method, since the properties of the obtained film greatly depend on the apparatus, these conditions and methods are not absolute.

Next, the structure of the magnetic film was examined by an X-ray diffraction method. According to this, it is found that Co (11.0) is strongly oriented. The average particle diameter was 10 nm from the plane observation by an electron microscope, and the particle diameter distribution was determined. The standard deviation: σ was 2 nm or less. Thus, it can be seen that the particles of the magnetic film are finer, the shape is the same as that of the disk substrate, and the particle size distribution is smaller. The number of crystal particles existing around one crystal particle was determined. When 250 crystal grains were examined, it was 6.01. This indicates that the magnetic crystal particles having a uniform hexagonal shape are regularly and continuously arranged two-dimensionally from the inorganic compound thin film layer (honeycomb structure). From the cross-sectional observation, it can be seen that the substrate and the magnetic film using the inorganic compound are epitaxially grown and have the same size as the crystal phase which is a solute of the inorganic compound thin film. Further, it was found that the structure of the cross section was also a good columnar structure, and the crystal grain size did not change from the substrate surface to the medium surface.

The magnetic characteristics of the magnetic film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10 ^-16 emu,
S is an index of the squareness of hysteresis in the MH loop
Was 0.8 and S † was 0.86, indicating good magnetic properties. This indicates that the crystal grain size of the magnetic film is small and the variation thereof is small.

Next, a lubricant was applied to the medium surface of a magnetic disk using a magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated using the same apparatus as in the second embodiment. For recording, a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used as the recording head.
Reproduction was performed by a head having a giant magnetoresistance effect. The distance between the head surface and the magnetic film is 20 nm. When a signal corresponding to ²⁰ Gbit / inch ² was recorded on this disk and the S / N of the disk was evaluated, a reproduction output of 32 dB was obtained.
Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was found that the size was about 3 particles from 2 and sufficiently small. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium. In addition, thermal fluctuation and demagnetization due to heat did not occur.
This is because the distribution of the crystal grain size of the magnetic film is small. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ when no signal processing was performed.
It was below.

Here, an example in which this inorganic compound is used for a glass substrate has been described. In this embodiment, an example was described in which cobalt oxide was used as a material to be precipitated as crystal particles and silicon oxide was used as a substance to be present in the grain boundary phase.However, this effect is not limited to cobalt oxide, and chromium oxide and nickel oxide can be used. Similarly, the compound to be added and the amount to be added may be determined based on the lattice constant of crystal grains of the magnetic film to be used. Furthermore, although silicon oxide was used as a substance to be present in the grain boundary phase, similar results were obtained by using aluminum oxide, titanium oxide, tantalum oxide or zinc oxide.

Embodiment 8 In this embodiment, the lattice spacing of the inorganic compound thin film produced by the ECR method is different from the lattice spacing of the information recording magnetic film by 10% or more. FIG. 8 is a schematic diagram showing a cross-sectional structure of the manufactured magnetic disk. As a substrate (1) for a magnetic disk, a 2.5 ″ diameter glass substrate was used. The material and size of the substrate used here are only one example, and a disk substrate of any size can be used. The effect of the present invention does not depend on the material and size of a substrate such as a metal such as aluminum or an aluminum alloy, or a resin such as amorphous polyolefin or polycarbonate. Needless to say, NiP may be formed on the substrate by a plating method.

On this substrate (1), an inorganic compound layer (2) was formed by ECR sputtering using microwaves. NiO and Al
_A mixture of ₂ O ₃ at a ratio of 2: 1 was used as a target, and pure Ar was used as a discharge gas. The pressure at the time of sputtering is 3 mTorr, the input microwave power is 1 kW, and an RF bias for drawing in the microwave is applied, and the value is 500 W. The thickness of the formed inorganic compound layer is 30 nm. Here, NiO
And the Al ₂ O _{3 2:} were mixed in a 1 was used sintered targets, may of course be used a complex target in which paste the NiO on Al ₂ O _3. The composition and sputtering conditions depend on the apparatus and are not absolute. Here, the ECR sputtering method is used because it is easier to control the energy of the sputtered particles as compared with the DC sputtering method and the RF sputtering method. By controlling this energy, the irregularities on the surface of the inorganic compound layer can be controlled to a desired value. In addition, NiO and Al ₂ O ₃
It goes without saying that it may be manufactured by a method of simultaneously sputtering this using an ECR dual source.

The inorganic compound layer (2) thus obtained
Was observed by TEM. Figure 2 shows a schematic diagram of the obtained image.
Shown in From this figure, it can be seen that it is an aggregate (honeycomb structure) of 10 nm regular hexagonal crystal grains, and the grains are regularly arranged. The distance between the crystal grains was 2 nm.
When each layer was analyzed by the μ-EDX method, hexagonal particles were nickel oxide and were crystalline particles. Crystal grain boundaries were formed so as to surround the periphery of the crystal grains, and aluminum oxide was present at the grain boundaries and was amorphous.

The cross section of this film was observed with a high-resolution TEM. According to this, the cross section of the formed inorganic compound film had a columnar structure without growing in a fan-like shape on the way. This indicates that the crystal grain size did not change even when the thin film grew. This change is the same even when the thickness of the inorganic compound thin film is increased. Also, near the substrate surface,
There was no such structure as the initial growth layer. This indicates that a film having a structure as shown in FIG. 2 can be obtained even with an extremely thin film. It can be seen that the surface of this film has irregularities. The convex portions were a crystalline phase, and the concave portions were an amorphous phase. Looking at the height, we focus on a certain mountain and use the AFM to determine the difference in height from the valley closest to that mountain.
Was 10 nm on average. this is,
This is the average value of the results of checking 500 samplings. When statistical processing was performed on the measured values, the standard deviation of the measured values was remarkably small at 0.5 nm or less, which is the lower limit of observation by an electron microscope. The distance between the peak and the valley was 5 nm. Since this thin film has crystal grains arranged two-dimensionally and regularly, and the shape and distribution of the irregularities are good, when used as a substrate for a magnetic disk, it can be used as a textured substrate. Can be. An arbitrary desired value can be obtained for the shape of the unevenness by controlling the film forming temperature, the sputtering speed, and the pressure of the atmosphere gas during the sputtering.

The unevenness of the surface of the substrate on which the inorganic compound thin film (2) was formed was measured. Prior to the measurement, first, the irregularities of the used glass substrate were examined by AFM. As a result, paying attention to the horizontal protrusion, the average of the distance to the closest protrusion is calculated.
(About 500 places), it was 50nm. Further, when the average of the difference in height between the convex portion in the vertical direction and the nearest concave portion was measured (about 500 locations), it was 60 nm. This value is the average of the results of examining several 300 μm squares. The surface irregularities after the formation of the inorganic compound film (2) on this substrate were 6 μm in the horizontal direction and 10 nm or less in the vertical direction (the AFM measurement lower limit or less). Here, the unevenness is even greater (horizontal: 3
Even when formed on a substrate (0 nm, vertical: 100 nm), the surface irregularities were the same, with a horizontal direction of 6 μm and a vertical direction of 10 nm or less (below the AFM measurement lower limit). As described above, by preparing the inorganic compound film (2) by the ECR sputtering method, a flat surface was obtained regardless of the unevenness of the substrate surface.

On this film, a magnetic film (3) and an inorganic compound film
Since the difference in lattice spacing from (2) was 10% or more, Cr was used as the lattice spacing adjusting layer (5) so that the difference was 10% or less.
Magnetic film through a ₉₀ Ti ₁₀ alloy thin film (3) was formed by DC sputtering. A Cr-Ti alloy was used as a target, and pure Ar was used as a discharge gas. The substrate temperature is 300 ° C., the discharge gas pressure is 3 mTorr, and the input DC power density is 1 kW / 150 mmφ. The fabricated film thickness is 75 nm. Subsequently, a magnetic film having a composition of Co ₆₉ Cr ₁₂ Pt ₁₉ was formed as a magnetic film (3) by DC sputtering. Pure Ar for discharge gas, Co ₆₉ Cr for target
_{A 12} Pt ₁₉ alloy target was used for each. The pressure during sputtering is 3 mTorr. The input DC power is 1kW / 150mmφ. During film formation, the substrate was heated to 300 ° C. The thickness of the magnetic film is 15 nm.

When the structure of the surface of the obtained magnetic film was observed by TEM, the structure of the formed magnetic film was found to be inorganic compound.
It had a shape reflecting the structure of (2). That is, Ni was precipitated as crystal particles corresponding to the crystal phase of the inorganic compound layer (2), the shape was a regular hexagon, and the size distribution was similar to that of the inorganic compound film. Further, when the cross-sectional structure was examined, it was found that the magnetic film grew from the inorganic compound layer via the lattice spacing control layer in a crystalline manner, resulting in a columnar structure.

As described above, the crystal grain size of the magnetic film can be controlled by epitaxially growing the magnetic film from the crystal phase of the inorganic compound. Unless the magnetic film was formed via the lattice spacing control layer, the particle size, particle size, particle size distribution, and cross-sectional structure did not depend on the inorganic compound layer. Regarding the orientation of the magnetic film, a columnar structure was not obtained, and the magnetic film was in a polycrystalline state. The magnetic properties of this magnetic film, particularly its coercive force and anisotropy, have been greatly degraded, and it has been difficult to use this magnetic film for ultra-high density magnetic recording exceeding ²⁰ Gbit / inch ² .
Further, the magnetic film formed in the amorphous region existing in the crystal grain boundary had a different structure from the magnetic film grown in the crystalline portion, and no columnar structure like the crystalline portion was observed.
Such a magnetic film has a different magnetism from that of the portion having the columnar structure, and has a semi-hard magnetic property. Thereby, the magnetic coupling between the magnetic particles can be reduced, and together with the reduction of the particle size distribution, the magnetic film is advantageous for high-density recording. In addition, when the magnetic film is manufactured by using the ECR sputtering method, it is possible to precisely control the size and regularity of crystal grains of the magnetic film.

Finally, as a protective film (4), a C film was formed to a thickness of 5 nm by a sputtering method. The sputtering conditions were as follows: input DC power density: 1 kW / 150 mmφ, discharge gas pressure: 5 mTorr
It is. Here, Ar was used as a sputtering gas,
It goes without saying that a gas containing nitrogen or a gas containing nitrogen and hydrogen may be used. This is because the particles obtained are finer and the resulting film is denser, and the protection performance can be improved. As for the film quality of this film, in addition to such a sputtering method, since the properties of the obtained film greatly depend on the apparatus, these conditions and methods are not absolute.

Next, the structure of the magnetic recording medium thus manufactured was examined by an X-ray diffraction method. As a result, 2θ = 6
The diffraction peak observed at around 2.5 ° corresponds to (220) of CoO of the solute in the inorganic compound layer. Also, 2θ =
The peak observed around 73 ° corresponds to (11.0) of Co in the magnetic film. As described above, Co is oriented because of epitaxial growth from the crystal phase in the inorganic compound film.
This is a result reflecting the orientation. When the inorganic compound film (2) does not exist, the (110) plane of Co is not observed,
(002) of Co was observed. This indicates that the inorganic compound film greatly contributes to the control of the orientation of the magnetic film. In addition, there was no change in the diffraction profile.

Next, from the observation of the plane by the electron microscope,
The average particle size of the magnetic film was 10 nm, and the particle size distribution was determined. The standard deviation: σ was 0.7 nm or less, and the particle size distribution was extremely small. This distribution is the same as the value in the inorganic compound film, and the crystal grain size and the distribution of the magnetic film reflect the value in the inorganic compound film. Further, the structure of the magnetic film was a honeycomb structure in which the crystal morphology of the magnetic particles and the crystal morphology of the inorganic compound were regularly arranged in a two-dimensional manner.

Next, the magnetic characteristics of the magnetic film were measured.
The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10
^As an index of the squareness of the hysteresis in the ^-16 emu and MH loops, S was 0.85 and S † was 0.90, indicating good magnetic properties. It can be seen that this is because the crystal grain size of the magnetic film is small and its variation is small, and the result reflects a reduction in magnetic interaction between crystal grains. Further, since there are almost no fine crystal grains, it can be seen that the magnetic recording medium is excellent in heat fluctuation.

Next, a lubricant was applied to the medium surface of the magnetic disk using the magnetic film having such magnetic characteristics, and the recording / reproducing characteristics of the disk (51) were evaluated. FIG. 4 shows an outline of the magnetic disk drive. As the magnetic head (53), a magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used for recording. Reproduction was performed by a head having a giant magnetoresistance effect. The magnetic head is controlled by a drive system (54). The distance between the head surface and the magnetic film is 15 nm. A signal equivalent to 40 Gbit / inch ² was recorded on this disk and the S / N of the disk was evaluated.
Was obtained.

Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), it was about three particles from two,
It turned out to be small enough. At the same time, the zigzag pattern existing in the magnetization transition region was significantly smaller than that of the conventional medium. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the distribution of the crystal grain size of the magnetic film is small. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed. Here, when the distance between the head and the surface of the magnetic recording medium was set to 15 nm, the head stably floated. However, when a magnetic disk having no inorganic compound layer produced by the ECR sputtering method was driven under the same conditions, a stable reproduction signal could not be obtained or a head crash occurred. The reason why a stable reproduction signal cannot be obtained is that the distance between the head and the surface of the magnetic recording medium is not constant because the unevenness of the recording medium surface exceeds the range in which the distance between the magnetic head and the medium can be controlled to be constant. It is.

[0087]

According to the present invention, a magnetic recording medium is epitaxially grown on an inorganic compound substrate or a thin film having a remarkably small particle size distribution, whereby the crystal grains of the magnetic recording medium can be miniaturized, the orientation can be controlled, and the crystallinity can be controlled. It is possible to reduce the distribution of the particle size and to regularly arrange the crystal particles.
In particular, in the arrangement of crystal grains, the number of crystal grains existing around one crystal grain is important. This is because it is possible to determine the two-dimensional arrangement of magnetic crystal particles having a uniform hexagonal shape. This allows
By reducing the crystal grain size of the magnetic film and its distribution, it is effective in reducing noise and reducing thermal fluctuation and thermal demagnetization when a disk is formed. Further, by controlling the orientation of the magnetic film, 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 magnetic crystal grains can be reduced. Accordingly, high-density recording can be performed by reducing medium noise and miniaturizing the size of the magnetic domain to be formed.

By integrating the above technologies, 40 Gbit
Ultra-high density magnetic recording exceeding / inch ² was realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cross-sectional structure of an inorganic compound thin film.

FIG. 2 is a schematic diagram showing the results of TEM observation of an inorganic compound thin film.

FIG. 3 is an X-ray diffraction profile of an inorganic compound thin film.

FIG. 4 is a schematic diagram showing a cross-sectional structure of a magnetic disk.

FIG. 5 is an X-ray diffraction profile of a magnetic recording medium.

FIG. 6 is a configuration diagram of a magnetic disk drive.

FIG. 7 is a schematic diagram showing a cross-sectional structure of a magnetic disk.

FIG. 8 is a schematic diagram showing a cross-sectional structure of a magnetic disk.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 inorganic compound film 3 magnetic film 4 protective film 5 lattice spacing control film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruaki Takeuchi 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Koichiro Wakabayashi 1-1-88 Ushitora, Ibaraki City, Osaka Hitachi Maxell Corporation F-term (reference) 5D006 BB01 BB04 BB07 CA01 CA05 DA03 EA03 FA09 5D112 AA03 AA05 AA24 BB05 BB06 BD03 FA04

Claims (22)

[Claims] 1. A method for manufacturing a magnetic recording medium having at least a substrate, an inorganic compound thin film, a magnetic film, and a protective film,
A method for producing a magnetic recording medium, comprising forming the inorganic compound thin film by an ECR sputtering method using microwaves. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the inorganic compound thin film comprises at least one oxide selected from the group consisting of cobalt oxide, chromium oxide, iron oxide and nickel oxide. An inorganic material having a structure in which at least one oxide selected from silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide is present as a crystal grain boundary phase so as to surround the crystal grains. A method for producing a magnetic recording medium, which is a compound. 3. The method of manufacturing a magnetic recording medium according to claim 2, wherein the inorganic compound thin film further has a hexagonal shape of the crystal grains, and an aggregate thereof has a honeycomb structure, A method for manufacturing a magnetic recording medium, wherein the particles are regularly arranged two-dimensionally. 4. The method for manufacturing a magnetic recording medium according to claim 3, wherein the crystal particles precipitated in the inorganic compound thin film are X-ray crystalline and exist at the grain boundaries of the crystal particles. Wherein the compound is X-ray amorphous. 5. The method for manufacturing a magnetic recording medium according to claim 3, wherein the standard deviation of the size of the crystal grains is 10% or less of the grain size, and the grain size distribution is a normal distribution. A method for manufacturing a magnetic recording medium. 6. The method for manufacturing a magnetic recording medium according to claim 3, wherein the structure of the inorganic compound thin film in the thickness direction is a columnar structure. 7. The method for manufacturing a magnetic recording medium according to claim 3, wherein crystal grains precipitated in the inorganic compound thin film are crystallographically oriented. 8. The method of manufacturing a magnetic recording medium according to claim 3, wherein the inorganic compound thin film has a crystal orientation and a lattice of crystal grains such that the thin film is epitaxially grown on the crystal grains of the inorganic compound thin film. A method for manufacturing a magnetic recording medium, characterized in that a surface distance is controlled. 9. The method for manufacturing a magnetic recording medium according to claim 3, wherein a concentration (composition) of a substance forming the crystal grains is set.
By selecting a solute or / and a solvent substance, selecting a preparation method, and / or selecting a preparation condition,
A method for manufacturing a magnetic recording medium, wherein at least one parameter selected from the structure, orientation, and crystal grain size of the inorganic compound thin film is controlled. 10. The method for manufacturing a magnetic recording medium according to claim 3, wherein the inorganic compound thin film is formed in a plate shape. 11. The method for manufacturing a magnetic recording medium according to claim 10, wherein the crystal grains precipitated in the inorganic compound have a columnar structure in a thickness direction of the plate. Manufacturing method. 12. The method according to claim 3, wherein the inorganic compound thin film is formed on a substrate.
A magnetic recording medium characterized in that grains are grown in a direction perpendicular to the substrate on which the crystal grains in the obtained thin film are formed, and the structure is a columnar structure, and the crystal is oriented in a certain direction. Manufacturing method. 13. The method of manufacturing a magnetic recording medium according to claim 3, wherein the precipitated particles of the solvent substance in the grain boundary phase of the inorganic compound thin film are oriented in a certain direction, and the crystal structure of the particles is the same. A method for manufacturing a magnetic recording medium, wherein the crystal structure or the crystal plane spacing of an inorganic compound thin film is the same or similar. 14. The method for manufacturing a magnetic recording medium according to claim 13, wherein the crystal orientation of crystal grains of the inorganic compound thin film is controlled in a desired direction. 15. The method of manufacturing a magnetic recording medium according to claim 13, wherein the orientation of the crystal orientation of the crystal grains of the inorganic compound thin film is controlled in accordance with the crystal structure of the magnetic film grown thereon. A method for manufacturing a magnetic recording medium, comprising: 16. The method of manufacturing a magnetic recording medium according to claim 13, wherein a magnetic film is epitaxially grown from crystal grains in the inorganic compound thin film, and the growth of the magnetic recording medium is suppressed by the crystal grains. Alternatively, a method of manufacturing a magnetic recording medium, wherein the structure of a film obtained by using crystalline particles and amorphous particles surrounding the crystalline particles is changed. 17. The method for manufacturing a magnetic recording medium according to claim 16, wherein the size of crystal grains of the magnetic film is made equal to the size of crystal grains of the inorganic compound thin film. 18. The method of manufacturing a magnetic recording medium according to claim 13, wherein the inorganic compound thin film and the magnetic film have similar or equal crystal structures and a lattice of crystal grains of the inorganic compound thin film. A method for manufacturing a magnetic recording medium, wherein the difference between the constant and the lattice constant of the magnetic film is within ± 10%. 19. The method for manufacturing a magnetic recording medium according to claim 18, wherein a gap between the inorganic compound thin film and the magnetic film is
The provision of a thin film layer for alleviating the difference in lattice constant between the two layers, which is within 10%, facilitated the magnetic recording medium to epitaxially grow from the crystal grain layer in the inorganic compound thin film. A method for manufacturing a magnetic recording medium, comprising: 20. The method for manufacturing a magnetic recording medium according to claim 13, wherein the magnetic film is mainly composed of Co,
A method for manufacturing a magnetic recording medium, comprising a ferromagnetic thin film of an alloy containing at least two elements selected from r, Pt, Ta, Nb, Ti, and Si. 21. The method for manufacturing a magnetic recording medium according to claim 13, wherein the magnetic film is composed of two phases, a crystalline phase and an amorphous phase, wherein the crystalline phase is mainly composed of Co, and Nd, P
r, Y, La, Sm, Gd, Tb, Dy, Ho, Pt, a phase containing at least one element selected from Pd, as an amorphous phase silicon oxide, zinc oxide, tantalum oxide, A method for producing a magnetic recording medium, wherein at least one compound phase selected from aluminum oxide is present so as to surround crystal grains. 22. The method of manufacturing a magnetic recording medium according to claim 21, wherein the form of the magnetic layer is a magnetic film having the same structure and the same size as the inorganic compound thin film. Manufacturing method.