JP2001195736A - Manufacturing method of magnetic recording medium - Google Patents

Abstract

(57) [Problem] To provide a method of manufacturing a magnetic recording medium capable of high density recording. SOLUTION: In the method for manufacturing a magnetic recording medium of the present invention,
Plasma is generated by resonance absorption, and a bias voltage is applied to draw the plasma toward the target and draw the target particles toward the substrate. At that time, the kinetic energy of the target particles can be made uniform, and the energy can be precisely controlled. By using this method in the manufacture of a magnetic recording medium, the crystal orientation of the magnetic layer, the orientation of crystal growth, the crystal structure, the particle size, and the like can be controlled, and material diffusion from other layers can be suppressed. The magnetic characteristics of the magnetic layer can be improved. In addition, since the protective layer can form a dense film that uniformly covers the magnetic layer, the thickness can be reduced. Therefore, a magnetic recording medium exceeding 40 Gbits / inch ² can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a magnetic recording medium suitable for high-density recording, and more particularly to a method of manufacturing a magnetic recording medium capable of recording bit information in a very small area of a magnetic layer.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable progress in the advanced information society, and multimedia capable of handling various forms of information has been rapidly spreading. A magnetic recording device mounted on a computer or the like is known as one of multimedia. At present, magnetic recording devices are being developed in the direction of miniaturization while improving recording density.

In order to realize high-density recording of a magnetic recording apparatus, (1) reducing the distance between a magnetic disk and a magnetic head, (2) increasing the coercive force of a magnetic recording medium, (3) signal There is a demand for speeding up the processing method and (4) developing a medium with small thermal fluctuation.

[0004] A magnetic recording medium has a magnetic layer formed by aggregating magnetic particles on a substrate, and information is recorded by several magnetic particles being collectively magnetized in the same direction by a magnetic head. You. Therefore, in order to realize high-density recording, in addition to increasing the coercive force of the magnetic layer, it is necessary to reduce the minimum area that can be magnetized in the same direction at a time in the magnetic layer, that is, the unit area where magnetization reversal can occur. is there. In order to reduce the magnetization reversal unit area, it is necessary to reduce the size of each magnetic particle or to reduce the number of magnetic particles constituting the magnetization reversal unit. For example, 40 Gbits /
In order to achieve a recording density exceeding inch ² (6.20 Gbits / cm ² ), it is necessary to control the magnetic particle diameter to 10 nm or less. In addition, when minimizing the magnetic particles, while reducing the variation of the particle size,
Measures to reduce thermal fluctuations are also needed. Attempts to achieve these are described, for example, in U.S. Pat.
As disclosed in JP-A-52-499, it has been proposed to provide a seed film between a substrate and a magnetic layer.

[0005]

However, in the above-described method of providing a magnetic layer on a substrate via a seed film, there is a limit in controlling the magnetic particle diameter and its distribution in the magnetic layer. For example, in order to obtain magnetic particles of a magnetic layer having a particle diameter of about 10 nm, even if the seed film material, film formation conditions, structure of the seed film, and the like are adjusted, the particle diameter distribution is broad, and is about twice as large as 10 nm. Coarse particles or conversely, 1
Particles fined to about 1/2 of 0 nm were considerably mixed. Among the magnetic particles, a magnetic particle having a particle diameter larger than the average causes an increase in noise during recording / reproducing, and a magnetic particle having a particle diameter smaller than the average causes an increase in thermal fluctuation during recording / reproducing. . In addition, as a result of a mixture of magnetic particles of various sizes, the boundary line between the region where the magnetization reversal has occurred and the region where the magnetization reversal has not occurred exhibits a coarse zigzag pattern as a whole, which also contributes to an increase in noise. I was Further, the number of magnetic particles constituting the magnetization reversal unit in the magnetic layer of the conventional magnetic recording medium was relatively large, from 5 to 10.

[0006] Further, it has been studied to reduce the distance between the magnetic layer of the magnetic head and the magnetic recording medium to 15 nm or less for high-density recording. Generally, scratches and rough irregularities exist on the surface of the substrate, and therefore, rough irregularities derived from the substrate are generated on the surface of the magnetic recording medium manufactured by laminating films on the substrate. If the distance between the magnetic recording medium and the magnetic head is reduced, the magnetic head cannot stably fly due to such rough irregularities, deteriorating the recording / reproducing characteristics, or causing the magnetic head to collide with the magnetic recording medium. The problem that both were damaged occurred. Therefore, there is a demand for a technique for forming a flat film without being affected by the roughness of the substrate surface.

On the other hand, as the distance between the magnetic head and the magnetic layer is reduced, the necessity of protecting the magnetic layer from the impact from the magnetic head and the environment in which the magnetic layer is used increases. therefore,
It is necessary to form a protective film for protecting the magnetic film so as to be more uniform and not to cause defects. However, in order to realize a distance of 15 nm or less between the magnetic head and the magnetic layer, the protective film formed on the magnetic layer must have a thickness of 5 nm.
It is necessary to have the following film thickness. Even if the carbon protective film is formed to a thickness of 5 nm or less by using the conventional DC sputtering method or magnetron sputtering method, the carbon protective film is formed only in an island shape, or defects such as holes and cracks occur in the protective film. In addition, the surface of the magnetic recording medium could not be completely covered with the protective film. Therefore, the magnetic layer may be corroded, or the magnetic layer may be physically damaged due to a head crash or the like.

Accordingly, a first object of the present invention is to provide a magnetic recording medium having low noise, low thermal fluctuation and low thermal demagnetization by reducing the magnetic particle diameter in the magnetic layer and suppressing the dispersion of the magnetic particle diameter. It is to provide a manufacturing method.

A second object of the present invention is to provide a method for manufacturing a magnetic recording medium suitable for high-density magnetic recording by controlling the crystal orientation of the magnetic layer.

A third object of the present invention is to provide a method for manufacturing a magnetic recording medium suitable for high-density recording by reducing the magnetic interaction between magnetic particles to reduce the unit of magnetization reversal during recording or erasing. Is to provide.

A fifth object of the present invention is to provide a magnetic recording medium constituted by laminating flat films, and an ultra-thin protective layer for covering the magnetic layer surface of the magnetic recording medium with a uniform thickness. An object of the present invention is to provide a method for manufacturing a magnetic recording medium.

Further, a sixth object of the present invention is to provide a 40 Gb
It is an object of the present invention to provide a method for manufacturing an ultra-high density magnetic recording medium exceeding it / inch ² .

[0013]

According to a first aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium comprising a magnetic layer for recording information and a protective layer on a rigid substrate. Then, a plasma is generated by resonance absorption, the generated plasma collides with a target to sputter target particles, and a bias voltage is applied between the substrate and the target, whereby the sputtered target particles are deposited on the substrate. A method for manufacturing a magnetic recording medium is provided, wherein at least one of the magnetic layer and the protective layer is formed by depositing while guiding.

FIG. 8 shows a method of manufacturing a magnetic recording medium according to the present invention.
This will be described below with reference to FIG. FIG. 8 shows an ECR (Electron
1 is a schematic sectional view of a (cyclotron resonance) sputtering apparatus 80.

The ECR sputtering apparatus 80 mainly includes a first chamber 81 in which plasma is generated, an annular target 70 connected above the first chamber 81, and a second chamber 83 connected above the target 70. To have. The first chamber 81 is a cylindrical tube made of quartz, and is provided with a pair of coils 64 and 66 circling upward and downward in the axial direction, respectively. A microwave generator 74 is connected to the first chamber 81 via an introduction tube, and the introduction tube is connected between the coils 64 and 66 of the first chamber 81. The second chamber 83 is a vacuum chamber made of metal, on the top of which a substrate 68 for depositing particles hit from the target 70 is installed. Further, a coil 62 for converging (suppressing divergence) the plasma extracted by the applied bias is provided above the second chamber 83. Target 7
0 and the substrate 68 installed in the second chamber 83 are connected to a power supply 90 so that a bias voltage can be applied.

The inside of the first chamber 81, the inside of the target 70 and the inside of the second chamber are communicated with each other and are closed from the outside. During operation of the apparatus, a shared space inside the first chamber 81, inside the target 70 and inside the second chamber 83 is decompressed by a vacuum pump (not shown), and gas is supplied into the first chamber 81 through a gas supply port (not shown). (For example, Ar) is introduced. Next, a constant magnetic field is applied to the inside of the device using the coils 64 and 66. Due to this magnetic field, free electrons existing inside the device perform cyclotron motion clockwise around the magnetic field axis. For example, when the electron density is about 10 ¹⁰ cm ⁻³ , the angular frequency of the electron cyclotron motion is about 10 ⁹ Hz, which is an angular frequency in a microwave region. When the generated microwave is introduced from the microwave generator 74 into this magnetic field, the microwave resonates with the cyclotron motion of the electrons, and the energy of the microwave is absorbed by the electrons (for convenience, here, this phenomenon is referred to as a phenomenon). Called resonance absorption). Due to this resonance absorption, the electrons gain high energy and are accelerated, collide with the gas and cause ionization of the gas, and the high energy E
A CR plasma 76 is generated in the first chamber 81.
Here, since a certain level of energy is given to the electrons by resonance absorption, the energy state of the electrons is also at a certain high energy level. Since such electrons collide with the gas to generate plasma, the particles that make up the plasma have high energy, and the energy of each particle is more uniform than that of normal plasma generated by discharge, etc. A narrow plasma is obtained.
An annular target 70 above the plasma generation position
Since a bias voltage is applied between the substrate and the substrate 68, the generated plasma is drawn out toward the target 70 and collides with the target 70 to strike out target particles. At this time, by changing the bias voltage, it becomes possible to precisely control the kinetic energy of the plasma colliding with the target 70 and, moreover, the kinetic energy of the target particles struck out by the plasma. The target particles whose energy is controlled in this manner are directed to the substrate 68 as a flow 72 of the target particles as shown in the figure, and are deposited on the substrate 68 with a uniform thickness.

When the above-mentioned ECR sputtering method is used for manufacturing a magnetic recording medium, the density, surface flatness, crystal orientation, and crystal growth of a thin film to be formed can be properly selected by selecting a material and film forming conditions. , Crystal structure, and crystal particle diameter can be controlled to desired values. Also, this ECR
When a sputtering method is used, when two or more thin films are formed, material diffusion between the thin films can be suppressed. For example, if a protective layer is formed on a magnetic layer by this method, the magnetic properties of the magnetic layer can be prevented from being impaired by the diffusion of the components of the magnetic particles into the protective layer. In addition, the use of this technique can reduce crystal defects in the formed thin film. For this reason, a dense film can be formed and a crystal which is strongly oriented in a certain direction can be obtained.

In order to excite electrons by resonance absorption, it is possible to use electromagnetic waves in a region other than microwaves, but it is preferable to use microwaves. Further, as a bias power source for controlling the kinetic energy of the plasma and the target particles to a constant value, a radio frequency (R
It is preferable to use the AC power supply or the DC power supply (DC) of F). For example, a DC power supply can be used for conducting ECR sputtering of a conductive material such as carbon, and an RF power supply can be used for carrying out ECR sputtering of a nonconductive material such as silicon oxide.

In the present specification, the resonance absorption means that the angular frequency of a particle that periodically moves at a specific angular frequency under the action of an external force substantially coincides with the frequency of an electromagnetic wave incident from the outside. In this case, a particle that moves in a periodic motion absorbs the energy of the electromagnetic wave, and the amplitude in the periodic motion of the particle, that is, a phenomenon in which the energy of the particle significantly increases.

According to a second aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium comprising an underlayer and a magnetic layer for recording information on a rigid substrate, comprising the steps of: Is generated, and the generated plasma collides with the target to sputter the target particles, and a bias voltage is applied between the substrate and the target, so that the sputtered target particles are deposited while being guided on the substrate. There is provided a method for manufacturing a magnetic recording medium, comprising forming the underlayer.

In the manufacturing method according to the second aspect of the present invention,
Prior to the formation of the magnetic layer, a base layer is formed by using the above-described ECR sputtering method. By forming the magnetic layer on the underlayer, the crystal structure, crystal orientation, crystal grain size,
At least one parameter among the particle size distribution, the density of the formed film and the flatness of the surface can be controlled more precisely. Thereby, a magnetic recording medium capable of ultra-high density recording can be manufactured.

The underlayer is formed by the above-mentioned ECR sputtering method, and is composed of a crystalline portion composed of crystal particles having a uniform particle diameter and an amorphous portion, and the crystal particles have a uniform width. It is possible to have a structure separated by an amorphous portion (a grain boundary portion). As described later, in order to sufficiently suppress the magnetic interaction between magnetic particles in the magnetic layer, the width of the crystal grain boundary is preferably 0.5 to 2 nm. Further, by using the above-mentioned ECR sputtering method, the crystal grains of the underlayer can be oriented in a certain crystal orientation. When the above-described ECR sputtering method is used, the structure of the underlayer can be controlled to a desired structure by changing the material and the film formation conditions to control the crystal grain diameter, the width of the grain boundary, the crystal orientation, and the like. . For example, in an example described later, a base layer in which hexagonal crystal grains were regularly arranged in a honeycomb shape via a crystal grain boundary portion could be formed. The number of crystal particles precipitated around one crystal particle was 5.9 to 6.1, and an underlayer having a very regular honeycomb structure could be formed. Such an underlayer is
Crystal grains are formed of cobalt oxide, chromium oxide, magnesium oxide, iron oxide or nickel oxide, or a combination of these oxides, and the crystal grain boundary portion is silicon oxide, aluminum oxide, titanium oxide, tantalum oxide or zinc oxide, Alternatively, they can be formed using a combination of these oxides. The thickness of such an underlayer is 2 to 50 n.
m is preferred.

As the underlayer, a thin film having a bcc structure or a B2 structure may be used in addition to the layer composed of the above compound. In particular, an inorganic compound such as magnesium oxide, chromium, nickel, a chromium alloy, or a nickel alloy can be used for the underlayer having these structures. These alloys include chromium, titanium, tantalum, vanadium, ruthenium, tungsten, molybdenum, vanadium, niobium, nickel, zirconium or aluminum, or a combination of these elements, in addition to the base element chromium or nickel. It is preferable that the underlayer is oriented in a certain direction. The thickness of such an underlayer is preferably 2 to 10 nm.

In forming the magnetic layer, it is preferable to epitaxially grow the magnetic layer on the underlayer whose structure is controlled as described above. As a result, the obtained magnetic layer reflects the structure of the underlayer, and the magnetic particles grown on the crystal grains of the underlayer are evenly separated by the non-magnetic portions grown on the crystal grain boundaries of the underlayer. Structure. Therefore, the magnetic interaction between the magnetic particles can be reduced, and the unit of magnetization reversal can be reduced. In addition, the particle size of the magnetic particles becomes equal to the crystal particle size of the underlayer, which makes it possible to reduce the size of the magnetic particles and reduce the variation in the particle size. Therefore, a magnetic recording medium with small thermal fluctuation and thermal demagnetization can be obtained. In the examples described later, the standard deviation (σ) in the distribution of the magnetic particle diameter was 8% or less of the average particle diameter, and the dispersion of the particle diameter could be reduced. Furthermore, the crystal grains can be oriented in a certain direction by epitaxially growing the magnetic grains on the crystal grains of the underlayer. In Examples described later, Co (11.0) crystal orientation suitable for high-density recording was obtained for Co in the magnetic layer. further,
When the magnetic layer is formed by the sputtering method using resonance absorption described above, the structure and orientation of the magnetic layer can be more precisely controlled, and the epitaxial growth of the magnetic layer from the underlayer is promoted. It is more suitable for high-density recording than a film formed by a magnetron sputtering method.

The material of the magnetic layer is an alloy mainly composed of cobalt. It preferably contains holmium or europium, or a combination of these elements. If the magnetic layer contains chromium, tantalum, niobium, titanium, silicon, boron or phosphorus, or a combination thereof, those elements precipitate (segregate) near or at the crystal grain boundaries of the cobalt crystal grains. This segregation can also reduce the magnetic interaction between the magnetic particles.

As the magnetic layer, a magnetic film having a granular structure in which metal crystal grains are surrounded by an amorphous phase may be used. The crystal particles are cobalt or an alloy mainly containing cobalt, neodymium, praseodymium,
Yttrium, lanthanum, samarium, gadolinium,
It preferably contains terbium, dysprosium, holmium, platinum or palladium, or a combination of these elements. Further, the amorphous portion existing so as to surround the metal crystal particles is preferably silicon oxide, aluminum oxide, titanium oxide, zinc oxide, silicon nitride, or a combination of these compounds. In the magnetic film having the granular structure, the presence of the amorphous portion can reduce the magnetic interaction between the magnetic particles as in the above-described segregation.

A plurality of underlayers can be provided as necessary. For example, when the difference in lattice constant between the underlayer and the magnetic layer is large, inserting a layer having an intermediate lattice constant between the two layers can promote favorable epitaxial growth of the magnetic layer. In this case, the magnetic layer may be formed via a magnesium oxide layer or an alloy layer mainly composed of chromium or nickel in addition to the underlayer. (In the examples described later, the underlayer and the control layer are described to distinguish a plurality of underlayers.)

Further, in order to shield the magnetic layer from the outside air and protect the magnetic layer from an impact received from the magnetic head, a protective layer is formed on the magnetic layer (the side in contact with the magnetic head) by using the above-mentioned ECR sputtering method. Can be formed. As described above, the thickness of the protective layer has an upper limit for high-density recording, and needs to be 5 nm or less. When the above-described ECR sputtering method is used, the kinetic energy of the target particles can be controlled. Therefore, even if the film thickness is reduced, a dense protective layer that covers the magnetic layer with a uniform thickness can be formed. In order to form a stable protective layer by this method, a film thickness of 1 nm or more is required, which is extremely thin as compared with the conventional 10 nm. When the above-described sputtering method is used when the protective layer is a carbon film, the density of the carbon film is 60% or more of the theoretical density (the density in a state where carbon atoms are deposited without voids),
It becomes possible to form a denser film as compared with the conventional 40 to 50%. The hardness of the film is more than twice that of a film formed by a conventional sputtering method (such as an RF magnetron method).

The protective layer is preferably a carbon thin film. The formation of the protective layer can be performed in a discharge gas atmosphere mainly composed of argon. The protective layer is preferably formed in a mixed gas atmosphere in which argon contains at least one gas selected from nitrogen and hydrogen. When a film is formed using the above mixed gas, nitrogen and hydrogen are contained in the obtained thin film, whereby the densification of the carbon thin film serving as the protective layer can be promoted.

Further, as shown in the measurement results by an atomic force electron microscope (AFM) in an example to be described later, when an underlayer is formed by ECR sputtering, the film can be formed without being affected by scratches or rough irregularities on the substrate surface. The surface can be flattened. On the other hand, on the surface of the magnetic layer, by growing the magnetic layer epitaxially on the underlayer, the growth rate is slightly different between the crystal grains of the underlayer and the crystal grain boundaries. An uneven pattern appears. Further, when a protective layer is formed on this magnetic layer by ECR sputtering,
Since the protective layer covers the surface of the magnetic layer with a uniform thickness, the surface of the protective layer has a shape reflecting a regular uneven pattern of the magnetic layer. This minute concavo-convex pattern is useful as a texture for causing the magnetic head to stably fly above the magnetic recording medium.

According to the method described above, the areal recording density is 4
A magnetic recording medium capable of high-density recording exceeding 0 Gbits / inch ² can be manufactured.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a magnetic recording medium according to the present invention will be specifically described with reference to the following examples. However,
The present invention is not limited to these examples.

[0033]

Embodiment 1 In this embodiment, as shown in FIG.
A method for manufacturing a magnetic disk 10 having a base layer 2, a control layer 3 for matching lattice constant, a magnetic layer 4, and a protective layer 5 in this order, and characteristics of each obtained layer and magnetic disk The measurement result will be described. Underlayer 2,
The control layer 3 and the protective layer 5 are formed using the above-described ECR sputtering method, and the target 7 corresponding to each layer material is used.
The above-described ECR sputtering apparatus 80 provided with a zero was used.

(1) Formation of Underlayer Glass substrate 1 having a diameter of 2.5 inch (6.35 cm)
(68) A CoO—SiO ₂ film was formed as the base layer 2 on the ECR sputtering apparatus 80 shown in FIG. 8 by a reactive ECR sputtering method. C on the target 70
The o-Si alloy was subjected to a reactive ECR sputtering method using an Ar-O ₂ mixed gas as a discharge gas. The gas pressure at the time of sputtering was 3 mTorr (about 399 Pa), and the input microwave power (2.98 GHz) was 1 kW. Further, in order to draw the target particles struck out by the plasma 76 excited by the microwave toward the substrate 1 (68), the RF bias power supply 90 applies an RF bias voltage of 500 W to the target 70 and the substrate 1 (68). Applied in between. By such an ECR sputtering method, a CoO—SiO ₂ film as a base layer was formed to a thickness of 20 nm.

(2) Composition Analysis of Underlayer, Observation by TEM, μ-EDX Analysis and Analysis by X-ray Diffraction The composition of the underlayer formed as described above is determined by quantitative determination of Co and Si using fluorescent X-rays. Analysis showed a 2: 1 ratio of CoO to SiO ₂ .

The planar structure of the CoO—SiO ₂ film 2 was observed in a bright field using a high-resolution transmission electron microscope (TEM). FIG. 2 shows an outline of the observed image. As shown in the figure, the CoO—SiO ₂ thin film was an aggregate of regular hexagonal crystal grains 12, and the crystal grains 12 were regularly arranged two-dimensionally via the crystal grain boundary portions 14. Next, when the cross section of the thin film was observed, it was observed that the regular hexagonal crystal grains 12 had a columnar structure growing in a direction perpendicular to the substrate surface. That is, CoO-SiO
It was found that the entire _two films had a honeycomb structure.
Further, it was found that this columnar structure was epitaxially grown with a uniform particle diameter in the growth direction.

The energy dispersive X in the very small area of this film
Line analysis (μ-EDX analysis) was performed. As a result, the crystal grains were CoO, and SiO ₂ was present at the crystal grain boundaries. The distance between crystal grains (the width of the grain boundary) is 0.5 to
1.0 nm.

In order to examine the structure of the underlayer in more detail, a lattice image was observed. According to this, it was found that CoO was crystalline and SiO ₂ was amorphous. When the lattice constant was determined, it was almost equal to the value of Co.

Next, the TE of the surface of the thin film in the underlayer was determined.
Using the M observation results, the distribution of crystal particle diameters and the number of crystal particles existing around one crystal particle (hereinafter referred to as the number of coordinating particles) were analyzed. First, as for the crystal particle diameter, an average particle diameter was 10 nm when a particle randomly selected in a square having a side of 200 nm was examined. The distribution of the particle diameter was a normal distribution, and the standard deviation was 0.5 nm. Next, the number of coordinating particles was examined on 500 randomly selected crystal particles, and found to be 6.01 on average. This means that there is little variation in the crystal particle size,
This indicates that the regular hexagons of the crystal grains are very regularly arranged in a honeycomb shape in a plane parallel to the substrate surface.

The number of coordinating particles changes depending on the distance between crystal grains. Here, SiO ₂ has an important role to have regularity in the structure, SiO ₂ concentration was found to determine the spacing of the crystal particles forming. A desired value of the distance between the crystal grains can be easily and arbitrarily selected by changing the composition of the target (the ratio of Co to Si or the ratio of CoO to SiO ₂ ). For example, if the SiO ₂ concentration in the CoO—SiO ₂ film is increased, the distance between the crystal grains becomes longer. However, S
If iO ₂ is present in a large amount, the precipitation growth of CoO is suppressed, so that it is difficult to make the thickness more than 2 nm. However, it can be changed by optimizing the film forming process such as raising the substrate temperature. On the other hand, when the SiO ₂ concentration is lowered, the particle spacing becomes narrower (the crystal particles come closer to each other). At the same time, disturbances in the particle shape were observed. The number of coordinating particles was as large as about 7 or as small as 4 to 5 and the dispersion was large. Further, it was observed that the two-dimensional arrangement was disturbed and the honeycomb structure was broken. An appropriate range of the crystal grain interval is 0.5 to 2 nm, and in this embodiment, the SiO ₂ concentration is controlled to realize this.

Further, this CoO—SiO ₂ film was formed by a usual magnetron sputtering method, and compared with a case where the CoO—SiO ₂ film was formed by an ECR sputtering method. The structure of the CoO—SiO ₂ film formed by magnetron sputtering was
Was analyzed in the same manner as in the case of the above-mentioned film formed by the ECR sputtering method using the observation image obtained by the above-mentioned method. As a result, the average particle size was 10
nm and the particle size distribution is normally distributed,
The standard deviation (σ) was 1.2 nm, and the variation in particle diameter was larger than that of 0.7 nm of the film formed by the ECR sputtering method. When the number of coordinating particles was examined for 500 crystal particles, the average was 6.30.
It was found that the regularity was lower than that of 6.01 CoO—SiO ₂ films formed by CR sputtering. As described above, it has been found that the regularity of the structure of the formed underlayer can be greatly improved by using the ECR sputtering method.

Next, the underlayer CoO—SiO ₂
The structure of the film was analyzed by X-ray diffraction. FIG. 3 shows the obtained diffraction profile. According to this, 2θ = 62.
A diffraction peak of (220) of CoO in the underlayer was observed around 5 °. No other peak was observed. This indicates that CoO is crystal-oriented only in one direction in the thin film. This crystal structure can be changed by controlling film forming conditions and composition. That is, the orientation can be controlled.

Also, when the thickness of the underlayer was increased to about 100 nm, the crystal grain diameter was constant as in the case of the thin film. However, of the formed 30 nm underlayer, an initial growth layer having no regular honeycomb structure is observed at 20 nm from the substrate surface, and a film thickness of about 30 nm is required to obtain a stable columnar structure. I understand.
When the film thickness is 3 nm or less, it is difficult to form a stable film due to the convenience of a film forming apparatus.

(3) Formation of Control Layer, Observation by TEM and Analysis by X-ray Diffraction Next, the lattice matching between the underlayer 2 and the magnetic layer 4 is adjusted on the CoO—SiO ₂ film as the underlayer 2. An MgO film was formed by an ECR sputtering method as a control layer 3 for performing the control. MgO was used for the target 70, and Ar was used as the discharge gas. The gas pressure at the time of sputtering was 3 mTorr, and the input microwave power was 1 kW. Further, an RF bias voltage of 500 V was applied between the target 70 and the substrate 1 (68) in order to draw the plasma 76 excited by the microwave toward the target 70 and to attract the target particles toward the substrate 1 (68). . An MgO film was formed to a thickness of 3 nm by such an ECR sputtering method.

In the MgO film formed by the above-described method, no deviation from the stoichiometric composition was observed. In addition, in the surface observation by TEM, the control layer 3 had a honeycomb structure reflecting the CoO—SiO ₂ film as the underlayer 2. Using this observation image, the number of coordinating particles was determined for 500 crystal particles, and the average was 6.01. On the other hand, cross-sectional observation by TEM showed that the MgO film was epitaxially grown from the crystal grains of the underlayer 2. The analysis by X-ray diffraction method shows that MgO (1
Only 10) was observed, indicating that MgO in the control layer 3 was strongly crystallized.

(4) Formation of Magnetic Layer On the MgO film as the control layer 3,
The _{o 69 Cr 18 Pt 1 0 Ta} 3 film was formed by DC sputtering. The substrate was heated to 300 ° C. during the formation of the magnetic layer 4. A Co—Cr—Pt—Ta alloy was used for the target, and Ar was used for the sputtering gas. The gas pressure during sputtering is 3 mTorr, and the input DC power is 1 kW /
It was 150 mmφ. Thus, Co ₆₉ Cr
_{An 18} Pt ₁₀ Ta ₃ film 4 was formed to a thickness of 15 nm.

(5) Observation of the magnetic layer by TEM, lattice image observation, analysis by X-ray diffraction method and measurement of magnetic properties Co ₆₉ Cr ₁₈ which is the magnetic layer 4 formed as described above
The surface of the Pt ₁₀ Ta ₃ film was observed with a TEM. According to this, the Co ₆₉ Cr ₁₈ Pt ₁₀ Ta ₃ film is formed on the CoO—SiO ₂
It was found that the film had a similar honeycomb structure, reflecting the honeycomb structure of the film. The average particle diameter of the magnetic particles determined using this surface observation image was 10 nm, and σ in the particle diameter distribution was 0.6 nm. Thus, the magnetic layer 4
It was found that the magnetic particles of (1) became finer and had a small variation in particle diameter, and had the same form as the underlayer 2. Next, when the number of coordinating particles was determined for 500 magnetic particles, the average was 6.01 and was in good agreement with the value in the MgO film as the control layer 3. This means that the magnetic particles continuously grow upward from the underlayer 2 via the control layer 3 in the form of a regular hexagonal prism, and the regular hexagonal shape is regular on the plane parallel to the substrate surface as shown in FIG. (Honeycomb structure).

Next, Co ₆₉ Cr ₁₈ P which is the magnetic layer 4
After the formation of the t ₁₀ Ta ₃ film, the cross-sectional structure of this laminated body was observed by TEM.
Was observed. As a result, a lattice connection was observed among the underlayer 2, the control layer 3, and the magnetic layer 4, and it was found that the magnetic layer 4 was epitaxially grown from the control layer 3. In particular, the control layer 3
And a good columnar structure had grown up to the magnetic particles in the magnetic layer.

[0049] The magnetic particles of _{Co 69 Cr 18 Pt 1 0 Ta} 3 film as a result of the lattice image observed and described later X-ray diffraction is crystalline, while the interface between the magnetic particles (crystal particles) It was found to be polycrystalline. Here, the crystalline magnetic particles grow from the CoO-SiO ₂ film, which is the base layer 2, from the CoO portions, which are regular hexagonal crystal particles, via the control layer 3. The department is
It was found that it corresponded to the crystal grain boundary part of the CoO—SiO ₂ film.

The boundary (polycrystalline) of the magnetic particles in the Co ₆₉ Cr ₁₈ Pt ₁₀ Ta ₃ film behaves as a non-magnetic material, unlike the magnetic particles. Since this boundary exists between magnetic particles with a width of 0.5 to 1.0 nm, the magnetic interaction between adjacent magnetic particles is weakened. Therefore, individual magnetic particles (crystal particles) are recorded and
It is easy to behave independently at the time of magnetization reversal at the time of erasing, and the number of magnetic particles constituting the unit of magnetization reversal, that is, the magnetic film area can be reduced.

The structure of the laminated body of the underlayer 2, the control layer 3, and the magnetic layer 4 was analyzed by the X-ray diffraction method. FIG. 4 shows the obtained X-ray diffraction profile. 2 as shown
CoO—SiO ₂ that is the underlayer 2 near θ = 62.5 °
In addition to the peaks of CoO in the film and MgO in the control layer 3, a weak peak was observed around 2θ = 72.5 °.
Considering the observation result by TEM, this 2θ =
The peak around 72.5 ° corresponds to Co (11.
0), indicating that Co is strongly oriented. This Co (11.0) is an orientation suitable for high-density magnetic recording, as is well known. That is, in the crystal grains in the magnetic layer, Co is strongly oriented in this direction, indicating that the desired crystal orientation was realized in the magnetic layer.

The magnetic layer 4 of Co ₆₉ Cr ₁₈ Pt
The magnetic properties of the ₁₀ Ta ₃ film were measured. The obtained magnetic properties are as follows: coercive force is 4.0 kOe, Isv is 2.5 × 10
^-16 emu, S, which is an index of the squareness of the hysteresis in the MH loop, was 0.83, and S ^† was 0.89, indicating good magnetic properties. The reason why the index indicating the squareness is large (close to the square shape) is that the magnetic layer 4 passes through the control layer 3 to form the crystal grains and the crystal grain boundaries of the CoO—SiO ₂ thin film as the underlayer 2. This is because a structure in which the interaction between the magnetic particles is reduced is obtained as a result of the growth of the respective structures.

Here, the magnetic layer of Co ₆₉ Cr ₁₈ P
A t ₁₀ Ta ₃ film was formed by ECR sputtering, and analyzed by X-ray diffraction as in the case of the magnetic layer formed by DC sputtering in this example. As a result, the peak of (11.0) of Co near 2θ = 72.5 ° became stronger than when formed by the DC sputtering method, and the half-width of the peak became narrower. Therefore, it was found that the crystallinity of the magnetic layer was improved, and the desired orientation was more strongly obtained. As described above, by combining the ECR sputtering method and the control layer, the crystallinity of the magnetic layer could be greatly improved. As a result, the magnetic anisotropy could be further increased.

Here, in order to further reduce the difference in crystal lattice constant, a Cr layer is formed between the MgO film as the control layer 3 and the magnetic layer 4.
_{When a 90} Ru ₁₀ alloy layer is further provided, Cr ₉₀ Ru
It was found that the crystallinity of the magnetic layer was further improved as compared with the case without the ₁₀ alloy layer. In the same analysis by the X-ray diffraction method as in the case where the Cr ₉₀ Ru ₁₀ alloy layer is not provided, 2θ
= The intensity of the peak indicating (11.0) of Co near 72.5 ° increased, and the peak shape became sharper. In addition, the coercive force increases to 4.0 kOe, and the squareness of S is also increased to 0.4 kOe.
86, S ^† was 0.93. From this, it was found that by providing another control layer, the orientation of the magnetic layer could be more precisely controlled and the coercive force could be increased.
As described above, two or more control layers can be provided depending on the material, structure, and composition of the magnetic layer to be used.

(5) Formation of Protective Layer Finally, as the protective layer 5, a carbon film was formed by ECR sputtering. A ring-shaped carbon target was used for the target 70, and Ar was used for the discharge gas. The gas pressure during sputtering was 3 mTorr, and the input microwave power was 1
kW. Further, in order to draw the plasma 76 excited by the microwave toward the target 70 and draw the target particles toward the substrate 1 (68),
A DC bias voltage of 500 V was applied. Such an E
A carbon film as the protective layer 5 was formed to a thickness of 5 nm by CR sputtering. Thus, a magnetic disk 10 having the structure shown in FIG. 1 was obtained.

Here, the ECR sputtering method is used to form the carbon film, unlike the RF sputtering method or the DC sputtering method, in which an extremely thin film having a thickness of 2 to 3 nm has no pinholes and the magnetic layer is formed uniformly. This is because a dense film covered with the film thickness can be obtained. In addition to this, there is an advantage that damage to the magnetic layer when forming the protective layer is extremely small. In particular, 4
When performing high-density recording exceeding 0 Gbits / inch ² , the thickness of the magnetic layer needs to be 10 nm or less. In this case, the influence of the magnetic layer upon film formation becomes more and more remarkable, and the ECR sputtering method is very effective for forming a protective layer for ultra-high density magnetic recording.

(6) Evaluation of Magnetic Disk Further, a lubricant was applied on the protective layer 5 formed as described above to complete the magnetic disk 10. A plurality of magnetic disks 10 were manufactured by the same process, and these were assembled in a magnetic recording device. FIGS. 5 and 6 show a schematic configuration of the magnetic recording apparatus used in the present embodiment. FIG. 5 is a top view of the magnetic recording device 60, and FIG.
FIG. 3 is a sectional view of the magnetic recording device 60 at A ′. As a recording magnetic head, a thin film magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used. The magnetic gap was 0.12 μm. For reproduction, a magnetic head having a giant magnetoresistance effect of a dual spin valve type was used. The magnetic head for recording and the magnetic head for reproduction are integrated, and are shown as a magnetic head 53 in FIGS. The integrated magnetic head 53 is controlled by a magnetic head drive system 54. The plurality of magnetic disks 10
It is coaxially rotated by the spindle 52 of the rotation drive system 51. The distance between the magnetic head surface and the magnetic disk 10 is 15n
m. 40Gbits / inch on this disc
^When a signal corresponding to ² was recorded 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 number of particles was 2 to 3, which was sufficiently smaller than the conventional 5 to 10 particles. At the same time, the zigzag pattern corresponding to the boundary of the magnetization reversal region was significantly smaller than that of the conventional magnetic disk. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is because the variation of the magnetic particle diameter of the magnetic layer is reduced. When the defect rate of this disk was measured, it was 1 × 10 ⁻⁵ or less as a value when no signal processing was performed.

[0059]

Embodiment 2 In this embodiment, a material different from that of Embodiment 1 is used for the control layer for matching the lattice constant. However, the structure of the magnetic disk to be formed is the structure shown in FIG. Same as Example 1. Here, a Cr-W alloy film was used for the control layer. The ECR sputter device 80
0 is appropriately selected according to the material to be formed, and an apparatus having the same structure as the apparatus used in Example 1 except that the bias power supply 90 is replaced with an RF or DC power supply according to the film formation material. Using.

(1) Formation of Underlayer, Control Layer, Magnetic Layer and Protective Layer On a glass substrate having a diameter of 2.5 inches, the same underlayer as in Example 1 was formed by a reactive ECR sputtering method similar to that in Example 1. CoO-SiO ₂ film was formed. This CoO
On -SiO ₂ film, by ECR sputtering method to form a Cr-W alloy layer as a control layer. Cr-
W alloy was used, and Ar was used as a discharge gas. The gas pressure at the time of sputtering was 3 mTorr, and the input microwave power was 1 kW. A DC bias voltage of 500 V was applied between the substrate and the target in order to draw the plasma excited by the microwaves toward the target and simultaneously draw the target particles struck out by the plasma toward the substrate. Thus, a 3 nm-thick Cr-W alloy film was formed. On this control layer, DC sputtering was used to form Co as a magnetic layer.
_{A 69} Cr ₁₈ Pt ₁₀ Ta ₃ film was formed. The target is a Co-Cr-Pt-Ta alloy, and the discharge gas is Ar
Was used. Gas pressure during sputtering is 3 mTorr
r, the input DC power was 1 kW / 150 mmφ. Thus, a magnetic layer was formed to a thickness of 10 nm. Finally, a carbon film having a thickness of 5 nm was formed as a protective layer by the same ECR sputtering method as in Example 1.

(2) Analysis of magnetic layer by X-ray diffraction method, T
Observation by EM and Measurement of Magnetic Properties From the results of TEM observation of the surface after the formation of the underlayer and the formation of the magnetic layer, Co ₆₉ Cr ₁₈ Pt ₁₀
The average particle diameter of the magnetic particles in the Ta ₃ film is 10 nm,
CoO—SiO as an underlayer formed prior to the magnetic layer
It was found that the average crystal grain size of the _two films was almost the same. Σ in the particle size distribution of the magnetic particles in the magnetic layer was 0.7 nm. As described above, it was found that the magnetic particles of the magnetic layer were finer, and that the dispersion of the particle diameter was small. According to the cross-sectional observation result by TEM, it was found that the magnetic particles in the magnetic layer were epitaxially grown on the crystal grains in the underlayer via the control layer. Further, it was found that the structure of the cross section had a good columnar structure growing vertically upward from the substrate, and that the particle diameter did not change from the substrate surface to the magnetic layer surface.

Next, the magnetic layer of Co ₆₉ Cr ₁₈ P
After the formation of the t ₁₀ Ta ₃ film, the structure of this laminate was examined by X-ray diffraction. As a result, the (11.0)
Was strongly oriented. Further, the peak of Cr in the Cr—W film as the control layer was observed at around 2θ = 62.1 °. Co (11.0) is an orientation required for high-density recording, and it was found that a desired crystal orientation was obtained for Co in the magnetic layer.

The magnetic layer of Co ₆₉ Cr ₁₈
The magnetic properties of the Pt ₁₀ Ta ₃ film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10
^{-1 6} emu, M-H S is indicative of squareness of the hysteresis in the loop 0.85, S ^† is 0.90, had good magnetic properties.

(3) Evaluation of Magnetic Disk A lubricant was applied on the protective layer formed as described above to complete a magnetic disk. The above process was repeated to produce a plurality of magnetic disks, which were mounted on a spindle of a magnetic recording device. The configuration of the magnetic recording apparatus was the same as that of the first embodiment, and had the structure shown in FIGS. The distance between the magnetic head surface and the magnetic layer surface was kept at 15 nm. When a signal corresponding to 50 Gbits / inch ² was recorded on this magnetic disk and the S / N of the magnetic disk was evaluated,
A reproduction output of 32 dB was obtained.

Here, when the magnetization reversal unit was measured by MFM, three magnetic particles 2 were reversed at once with respect to the recording magnetic field applied when recording 1-bit data. This was found to be sufficiently smaller than 5 to 10 conventional magnetization reversal units. Along with this, the portion (zigzag pattern) corresponding to the boundary between adjacent magnetization reversal units was also significantly smaller than the conventional magnetic disk. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is an effect resulting from the small magnetic particle size distribution of the Co ₆₉ Cr ₁₈ Pt ₁₀ Ta ₃ film of the magnetic layer. Also,
When the defect rate of the disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

In this embodiment, the Cr--W alloy is used for the control layer. However, other than this, for example, a Ni--Al alloy or a Ni--T
Even when a Ni alloy such as an alloy a was used, the effect of favorably epitaxially growing the magnetic layer was obtained as in the case of the Cr alloy. In addition, depending on the difference in lattice constant between the magnetic layer and the underlayer, the control layer uses a multilayer film such as Cr / Cr-Ti / Ni-Ta, so that the mismatch of the crystal lattice can be further reduced. Can be improved in magnetic properties. In particular, when the thickness of the magnetic layer becomes an extremely thin film having a thickness of 10 nm or less, such a multi-layer control layer is effective in maintaining or improving magnetic characteristics. Further, when the structure of the control layer in contact with the magnetic layer is a bcc structure, Co has a (11.0) orientation,
The structure of this control layer is Co-Cr-Ru, Co-Cr,
In the case of an hcp structure such as Co-Ru, (112 ^*
0) Orientation. In addition, in this specification, "2 ^* " means 2 with an upper bar. In the case of a B2 structure such as Ni-Al-Cr, the orientation is (112 ^* 0). These are all orientations suitable for high-density recording.

In this embodiment, chromium is used as the crystalline material of the control layer. However, vanadium may be used instead. In order to change the lattice constant of the control layer in accordance with the lattice constants of the underlayer and the magnetic layer, elements such as titanium, aluminum, tantalum, nickel, and molybdenum can be added to vanadium in an amount of 5% to less than 50%.

[0068]

Embodiment 3 In this embodiment, a material different from that of Embodiment 1 was used for the magnetic layer, but the formed magnetic disk had the same structure as that of Embodiment 1 shown in FIG. Except for the magnetic layer, a magnetic disk was formed using the same material and method as in Example 1. In this embodiment, a CoPt—SiO ₂ -based granular magnetic film was used for the magnetic layer. The ECR sputtering device 80
Apparatus having the same structure as the apparatus used in Example 1 except that the target 70 is appropriately selected according to the material to be formed, and the bias power supply 90 is replaced with an RF or DC power supply according to the film formation material. Was used.

(1) Formation of Underlayer, Control Layer, and Magnetic Layer On a glass substrate having a diameter of 2.5 inches, the same underlayer as CoO-Si as in Example 1 was formed by ECR sputtering.
An O ₂ film and an MgO film as a control layer were formed. Next, a CoPt—SiO ₂ based magnetic layer having a granular structure was formed as a magnetic layer by ECR sputtering.
The target is a CoPt-SiO ₂ based mixture (mixing ratio is
CoPt: SiO ₂ = 1: 1. ) A target was used, and Ar was used as a sputtering gas. The discharge gas pressure during sputtering was 3 mTorr, and the input microwave power was 1 kW. In order to draw the plasma excited by the microwave in the direction of the target and at the same time the target particles struck out by the plasma in the direction of the substrate, 500 W
Was applied. The substrate was heated to 300 ° C. during the formation of the magnetic layer. By such an ECR sputtering method, a CoPt—SiO ₂ -based granular magnetic film as a magnetic layer was formed to a thickness of 10 nm.

The reason why the ECR sputtering method was used to form the magnetic layer was that the energy of the sputtered particles was controlled with high precision, so that the crystal grains in the underlayer were oriented through the control layer from the magnetic particles in the magnetic layer. This is because the particles can be favorably grown epitaxially.

(2) TEM observation of magnetic layer, AFM
Measurement of Magnetic Properties and Measurement of Magnetic Properties Using a TEM, the magnetic layer C
The cross section of the oPt—SiO ₂ based granular magnetic film was observed. The cross-sectional observation results show that CoPt, which is a magnetic particle in the magnetic layer, is epitaxially grown from the crystal grains in the underlayer via the control layer, and that a good columnar structure is grown upward from the underlayer. all right. On the other hand, SiO ₂ in the magnetic layer was grown from the amorphous phase (crystal grain boundary) surrounding the crystal grains in the underlayer via the control layer. That is, it was found that the individual magnetic particles composed of CoPt were surrounded by SiO ₂ , the magnetic particles were physically separated from each other with a uniform width, and had a structure capable of greatly reducing magnetic interaction. . This structure of the magnetic layer is effective for performing high-density recording on a magnetic recording medium. In addition, since the magnetic particles of the magnetic layer reflect the crystal particle size distribution of the underlayer, there are almost no magnetic particles that are too small, so that the magnetic particles are excellent in heat fluctuation.

Further, from observation of the surface of the magnetic layer by TEM, it was found that the surface had minute and regular irregularities. This unevenness reflects the unevenness of the underlayer surface,
When measured using an atomic force electron microscope (AFM), the horizontal distance between the peak (convex) and the peak is 6 μm, and the height of the peak, that is, the vertical distance between the peak and the valley (concave) is 10 nm or less ( Below the AFM measurement lower limit).

The magnetic layer Co thus prepared
The magnetic properties of the Pt—SiO ₂ based granular magnetic film were measured. The obtained magnetic properties show that the coercive force is 4.0 kOe and I
sv is 2.5 × 10 ⁻¹⁶ emu, S is an index of the squareness of the hysteresis in the MH loop is 0.85, S is
^† was 0.90, indicating good magnetic properties. This means that the magnetic layer has a small magnetic particle diameter and its variation is small, and furthermore, each magnetic particle has a uniform width S
The separation by iO ₂ indicates that the magnetic interaction between the magnetic particles has been reduced. In addition, it was found that when magnetic particles are formed by adding Pt to Co, the magnetic anisotropy of the magnetic particles increases and the coercive force also increases.

(3) Formation of Protective Layer and Observation by TEM On this CoPt—SiO ₂ -based granular type magnetic film as the magnetic layer, a carbon film as the protective layer was formed by the same ECR sputtering method as in Example 1. Formed. The thickness of the formed carbon film was 3 nm. Thus, a magnetic disk having the structure shown in FIG. 1 was formed. When the surface of the magnetic recording medium after the formation of the carbon film was observed by TEM, it was found that the surface had the same minute irregularities as the surface of the magnetic layer. Moreover, the surface of the magnetic layer was uniformly covered with the protective layer.

Further, in order to compare the magnetic characteristics with the magnetic disk in which each layer was formed by using the ECR sputtering method of this embodiment, a magnetic disk in which a protective layer was formed by using a magnetron type RF sputtering method was manufactured. The magnetic characteristics of the magnetic disk on which the protective layer is formed by this method are as follows.
It had fallen to 1.8 kOe. Moreover, its coercivity is
It was found that large unevenness occurred on one magnetic disk. As described above, when the ECR sputtering method is used to form the protective layer, not only can the magnetic layer be uniformly coated with a high-density carbon film without pinholes and cracks, but also the coercive force is improved as compared with other sputtering methods. It was found that damage to the magnetic layer at the time of forming the protective layer could be suppressed.

(4) Evaluation of Magnetic Disk A lubricant was applied on the carbon film as the protective layer formed as described above to complete the magnetic disk. A plurality of magnetic disks were manufactured by the same steps as described above, and these were assembled in a magnetic recording device. The magnetic recording apparatus had the same configuration as that of the first embodiment shown in FIGS. The distance between the magnetic head surface and the magnetic layer was 12 nm. The recording and reproduction characteristics of these magnetic disks were evaluated under the same conditions as in Example 1. When a signal corresponding to 50 Gbits / inch ² was recorded on the magnetic disk and the S / N of the disk was evaluated, a reproduction output of 30 dB was obtained.

Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), one or two particles were reversed at a time with respect to a recording magnetic field for recording 1-bit data. This is sufficiently smaller than the conventional 5 to 10 pieces.
At the same time, the zigzag pattern corresponding to the boundary between adjacent magnetization reversal units was significantly smaller than the conventional magnetic disk. This indicates that the boundaries of the magnetization reversal regions became smoother because the magnetic particles became finer and the units of magnetization reversal became smaller. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is an effect due to the reduced variation in the magnetic particle diameter of the magnetic layer. When the defect rate of this disk was measured, it was 1 × 10 ⁻⁵ or less as a value when no signal processing was performed.

Here, the distance between the magnetic head and the magnetic layer is 1
At 2 nm, the magnetic head stably floated. However, for comparison with the magnetic disk of this embodiment, the ECR
A magnetic disk having no underlayer formed by a sputtering method was manufactured, and was driven under the same conditions and a magnetic recording device. Then, a stable reproduction signal could not be obtained, or the magnetic head collided with the surface of the magnetic disk to cause damage.
This is because the surface of the magnetic disk has large irregularities and exceeds the range in which the magnetic recording device can control the distance between the magnetic head and the magnetic disk to be constant.

In this embodiment, CoPt is used as the magnetic layer material.
Although SiO ₂ was used, elements such as palladium, gadolinium, samarium, praseodymium, neodymium, terbium, dysprosium, holmium, yttrium, and lanthanum were added to the magnetic layer to improve the magnetic anisotropy of the magnetic particles. can do.

In this embodiment, the ECR sputtering method is used for forming the magnetic layer. However, a film forming method such as a magnetron sputtering method using a Co-SiO ₂ mixed (or composite) target may be used. However, in this case, since the shape of the magnetic particles becomes less uniform than when the ECR sputtering method is used, the magnetic characteristics and the recording / reproducing characteristics may slightly deteriorate. In addition, in a sputtering method other than the ECR sputtering method, material diffusion between the respective layers also occurs. When the magnetic layer is an ultrathin film having a thickness of 10 nm or less, the effect becomes remarkable, and the material diffusion between layers causes deterioration of magnetic characteristics and recording / reproducing characteristics. For these reasons, the method using resonance absorption is an effective method for stably forming a magnetic layer.

In Examples 1 to 3 above, the underlayer Co
When forming an O—SiO ₂ film, Co and S are used as targets.
A sintered body of a mixture with i was used. In addition, an underlayer may be formed by dual simultaneous sputtering using a single sintered body of each of these elements (compounds) as a target. Further, as used in Example 5 described later, an ECR sputtering method using Ar as a discharge gas may be used for a target obtained by mixing and sintering CoO and SiO ₂ at a ratio of 2: 1. A composite target in which CoO is attached on SiO ₂ may be used. In addition, a DC bias voltage may be applied to draw the target particles toward the substrate. By using the ECR sputtering method, the energy of sputtered particles can be precisely controlled, so that a film having a honeycomb structure similar to that of the above embodiment can be obtained using any target and bias voltage. However, reactive sputtering using a sputtering gas mixed with oxygen is an advantageous film forming method from the viewpoint of productivity because the film forming rate is high.

The Co in the underlayer used in Examples 1 to 3
In order to bring the lattice constant of O closer to the lattice constant of the magnetic layer, it is necessary to change the film formation conditions, or to use a metal (for example, chromium, iron, nickel, or the like) having a different ionic radius on CoO,
It can be controlled by adding oxides of these metals and forming a solid solution.

In Examples 1 to 3, CoO was used as the substance used for the crystal phase of the underlayer. However, hexagonal crystal particles similar to CoO can be obtained by using chromium oxide, iron oxide or nickel oxide. Further, although SiO ₂ is used as a material constituting the crystal grain boundary portion, crystal particles similar to SiO ₂ can be formed with a uniform width by using magnesium oxide, aluminum oxide, titanium oxide, tantalum oxide, or zinc oxide. The crystal grain boundary part separated by was obtained.

[0084]

Embodiment 4 The structure of the magnetic disk of the present embodiment is a structure having a base layer, a magnetic layer and a protective layer on a substrate, and is similar to Embodiment 5 described later, and FIG. 7 is a schematic sectional view. In this embodiment, using the MgO-SiO ₂ is a different material from the first to third embodiments the underlying layer. The method of manufacturing this magnetic disk and the measurement results will be described below. The ECR sputtering apparatus 80 is an apparatus used in the first embodiment except that the target 70 is appropriately selected according to the material to be formed, and the bias power supply 90 is replaced with an RF or DC power supply according to the film formation material. An apparatus having the same structure as that described above was used.

(1) Formation of Underlayer An MgO—SiO ₂ film as an underlayer was formed on a glass substrate having a diameter of 2.5 inches by ECR sputtering. A sintered body obtained by mixing MgO and SiO ₂ at a ratio of 3: 1 was used as a target, and Ar was used as a sputtering gas. The gas pressure at the time of sputtering was 3 mTorr, and the input microwave power was 1 kW. Further, an RF bias voltage of 500 W was applied between the substrate and the target in order to draw the plasma excited by the microwave in the direction of the target and simultaneously draw the target particles struck out by the plasma in the direction of the substrate. By such an ECR sputtering method, a MgO—SiO ₂ film was formed to a thickness of 20 nm.

(2) Observation of Underlayer by TEM, μ-E
The surface of the MgO-SiO ₂ film serving as an underlying layer formed as described analysis above by DX analysis and X-ray diffraction method was observed by TEM. Observed images were obtained in Examples 1 to
3 and the structure shown in FIG. From this observation result, it was found that the MgO—SiO ₂ film had a structure in which regular hexagonal crystal particles having a particle diameter of 10 nm were regularly arranged in a honeycomb shape. The distance between the crystal grains (the width of the crystal grain boundary portion) was 0.8 nm on average. A desired value of the distance between the crystal grains can be selected by changing the composition of the target (such as the ratio of MgO to SiO ₂ ).

According to the energy dispersive X-ray analysis (μ-EDX analysis) of the microscopic region, the regular hexagonal crystal particles
In gO, SiO ₂ was present at the grain boundary. Also, from the lattice image observation, MgO is crystalline and S
iO ₂ was found to be amorphous. When the lattice constant of the underlayer was determined, the C included in the constituent material of the magnetic layer was determined.
It was almost equal to the value of o.

Further, this MgO-SiO
_When the cross section of the _two films was observed, a columnar structure that grew upward from the substrate was observed. Therefore, it was found that the hexagonal columnar crystal grains were favorably grown epitaxially without changing the particle diameter.

Next, the number of coordinating particles was analyzed using a surface observation image of the MgO—SiO ₂ film by TEM. At that time, 500 randomly selected crystal grains were used for the analysis. First, when the crystal particle diameter was determined, the average particle diameter was 1
It was 0 nm. The distribution of particle size is normal distribution,
Σ of this distribution was 0.5 nm. Next, when the number of coordinated particles was determined, it was 6.02 on average. The number of coordinating particles changes depending on the width of the crystal grain boundary in addition to the distribution of the particle diameter and the particle shape. The average value of 6.02 indicates that crystal grains having a uniform hexagonal shape are arranged very regularly in a honeycomb shape.

The underlayer MgO—SiO ₂
The films were analyzed by X-ray diffraction. According to the result, 2
A diffraction peak of MgO is observed around θ = 62.5 °,
No other peak was observed. This is because Mg
This indicates that O is strongly oriented in a certain direction.
The MgO-SiO ₂ film formed here did not show any deviation from stoichiometry by using the ECR sputtering method. Therefore, it has been found that since free oxygen does not exist in the underlayer, the metal such as the magnetic layer is not oxidized, and a highly reliable magnetic disk can be obtained.

(3) Formation of Magnetic Layer This underlayer, MgO-SiO₂A magnetic layer on the film
Co₆₈Cr₁₇Pt₁₂Ta₃DC sputtering
It was formed by a method. During the formation of the magnetic layer, the substrate is kept at 300 ° C.
Heated. The target has the same composition as the target film composition
(Co₆₈Cr ₁₇Pt₁₂Ta₃) Co-Cr-P
t-Ta alloy and Ar as discharge gas
Was. The gas pressure during sputtering is 3 mTorr
DC power was 1 kW / 150 mmφ. in this way
Thus, a magnetic layer was formed to a thickness of 10 nm.

(4) Observation of Magnetic Layer by TEM, Analysis by X-ray Diffraction Method, and Measurement of Magnetic Properties The structure of the Co ₆₈ Cr ₁₇ Pt ₁₂ Ta ₃ film as the magnetic layer was observed by TEM. MgO-
Reflecting the structure and shape of the SiO ₂ film, it had a honeycomb structure similar to the underlying layer. The average particle diameter of the magnetic particles determined using this observation image was 10 nm, and σ in the particle diameter distribution was 0.6 nm or less. As described above, it was found that the magnetic particles of the magnetic layer were finer and the variation in the particle diameter was smaller, and the magnetic layer had the same form as the underlayer.
Next, the number of coordinated particles was determined. 500 randomly selected
When the number of magnetic particles was examined, the number of coordinating particles was 6.01 on average, which was in good agreement with the value in the previous underlayer. This indicates that the hexagonal column-shaped magnetic crystal grains having the same size are continuously grown on the crystal grains of the MgO—SiO ₂ film of the underlayer, and are arranged very regularly in a honeycomb shape. I have.

After the formation of the magnetic layer, the cross-sectional structure of the laminate was observed with a TEM. As a result, the MgO-
Co ₆₈ Cr ₁₇ Pt ₁₂ Ta _{3 of} SiO ₂ film and magnetic layer
A lattice connection was observed between the film and the film, and it was found that the magnetic particles in the magnetic layer were epitaxially grown on crystal grains in the underlayer. Further, although the magnetic particles of the magnetic layer grew as a good columnar structure from above the crystal grains of the underlayer, no clear structure was observed in the magnetic layer portion on the crystal grain boundary of the underlayer. It was an aggregate of crystals. Since such a polycrystal is non-magnetic, the magnetic layer grown reflecting the honeycomb structure of the underlayer has hexagonal magnetic particles separated by a non-magnetic portion having a uniform width, and the magnetic property between the particles is high. It was found that the structure had a significant reduction in the dynamic interaction.

Next, the laminate was analyzed by the X-ray diffraction method. As a result, in addition to the MgO peak around 2θ = 62.5 °, a weak peak was observed around 2θ = 72.5 °. This peak was found to be (11.0) of Co in the magnetic layer in consideration of the results of the structural analysis and the TEM observation of the MgO—SiO ₂ film as the underlayer. As is well known, (11.0) of Co is an orientation suitable for high-density recording, and it was found that a strong orientation was obtained in this desired direction.

The magnetic layer of Co ₆₈ Cr ₁₇
The magnetic properties of the Pt ₁₂ Ta ₃ film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10
^{-1 6} emu, M-H S is indicative of squareness of the hysteresis in the loop 0.83, S ^† is 0.89, had good magnetic properties. As described above, the index indicating the squareness is large (close to the square) because the magnetic layer grows reflecting the honeycomb structure of the underlayer, and the magnetic particles in the magnetic layer have a uniform width in the non-magnetic portion. This is because the magnetic interaction between the magnetic particles is reduced.

(5) Formation of protective layer Finally, a carbon film was formed as a protective layer by ECR sputtering. A ring-shaped carbon target was used as a target, and Ar was used as a discharge gas. The gas pressure during sputtering is 3 mTorr, and the input microwave power is 1 k
W (frequency was 2.93 GHz), and the substrate temperature was room temperature. An RF bias voltage of 500 W was applied between the target and the substrate in order to draw the plasma excited by the microwave in the direction of the target and simultaneously draw the target particles struck out by the plasma in the direction of the substrate. By such an ECR sputtering method, a carbon film was formed to a thickness of 3 nm. Thus, a magnetic disk having the same structure as that shown in FIG. 7 was manufactured.

(6) Evaluation of Magnetic Disk A lubricant was applied to the surface of the protective layer formed as described above to complete a magnetic disk, and this process was repeated to obtain a plurality of magnetic disks. These magnetic disks were mounted coaxially on a spindle, and incorporated in a magnetic recording apparatus having the same configuration as in Example 1 and shown in FIGS. Using this magnetic recording device, the recording and reproducing characteristics of the magnetic disk were evaluated. The distance between the magnetic head surface and the magnetic layer was kept at 11 nm. When a signal corresponding to 40 Gbits / inch ² was recorded on this disc and the S / N of the disc was evaluated, a reproduction output of 32 dB was obtained.

Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), two or three magnetic particles were reversed at once with respect to the recording magnetic field applied when recording 1-bit data. This is the conventional magnetization reversal unit 5
It was found to be sufficiently smaller than ten. At the same time, the portion (zigzag pattern) corresponding to the boundary between adjacent magnetization reversal units was significantly smaller than the conventional magnetic disk. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is an effect due to a reduction in the magnetic particle diameter of the magnetic layer and a reduction in the particle diameter. When the defect rate of this disk was measured, it was 1 × 10 ⁻⁶ or less as a value when no signal processing was performed.

In the present embodiment, the underlayer MgO--Si
Although SiO ₂ was used as the oxide present at the crystal grain boundaries of the O ₂ film, other than this, MgO—
As in the case of the SiO ₂ film, a crystal grain boundary part which uniformly separates crystal grains was obtained.

In this embodiment, the DC sputtering method is used for forming the magnetic layer, but the ECR sputtering method may be used. E
The CR sputtering method is more preferable because the crystal particle diameter of the magnetic layer and its distribution can be controlled with high accuracy.

In this embodiment, the RF voltage was applied when the protective layer was formed. However, since carbon is a conductor, a similar carbon film can be formed even when a DC voltage is applied and drawn.

In Examples 1, 2 and 4, the magnetic layer was
Although o-Cr-Pt-Ta was used, Co-
Ternary system such as Cr-Pt or Co-Cr-Ta, Co-Cr
A quinary system such as -Pt-Ta-Si may be used. Also,
Co-Cr-Pt- used in Examples 1, 2 and 4 above
In the Ta-based magnetic layer, any of palladium, terbium, gadolinium, samarium, neodymium, dysprosium, holmium, and europium may be used instead of platinum, and niobium may be used instead of tantalum.
Elements such as silicon, boron, and vanadium may be used,
A plurality of these elements may be included.

[0103]

Embodiment 5 In this embodiment, as shown in FIG.
A magnetic disk 30 was formed by sequentially forming a base layer 22, a magnetic layer 23, and a protective layer 24 on the substrate 1. A Co--Cr--Pt alloy different from that of Example 1 was used for the magnetic layer, but the same material as that of Example 1 was used for the underlayer and the protective layer. less than,
The method of manufacturing the magnetic disk 30 and the results of measuring characteristics will be described. The ECR sputtering apparatus 80 is an apparatus used in the first embodiment except that the target 70 is appropriately selected according to the material to be formed, and the bias power supply 90 is replaced with an RF or DC power supply according to the film formation material. An apparatus having the same structure as that described above was used.

(1) Formation of Underlayer A CoO—SiO ₂ film as the underlayer 22 was formed on a glass substrate 21 having a diameter of 2.5 inches by ECR sputtering. A sintered body obtained by mixing CoO and SiO ₂ at a ratio of 2: 1 was used as a target, and Ar was used as a sputtering gas. The gas pressure at the time of sputtering was 3 mTorr, and the input microwave power was 1 kW. An RF bias voltage of 500 W was applied between the substrate and the target in order to draw the plasma excited by the microwave in the direction of the target, and simultaneously draw the target particles struck out by the plasma in the direction of the substrate. This ECR sputtering method allows CoO-S
An iO ₂ film was formed to a thickness of 30 nm.

(2) TEM observation of the underlayer, μ-E
DX analysis and measurement by AFM CoO—SiO as underlayer 22 formed as described above
The surfaces of the _two films were observed by TEM. The obtained observation image was the same as in Example 1, and the underlayer surface had the same structure as in FIG. As shown in the figure, it was found that the underlayer 22 was an aggregate of regular hexagonal crystal grains, and the grains were regularly arranged in a honeycomb shape. The particle diameter of the crystal grains (the interval between the opposite sides of the regular hexagon) was 10 nm, and the distance between the crystal grains (the width of the crystal grain boundary) was 2 nm.

When the underlayer 22 was analyzed by the μ-EDX method, the hexagonal particles were CoO and were crystalline. A crystal grain boundary portion is formed so as to surround the periphery of the crystal grain, and the grain boundary portion is formed of SiO.
₂ was amorphous.

The cross section of the CoO—SiO ₂ film as the underlayer 22 was observed with a high-resolution TEM. As a result, the cross section of the formed underlayer 22 had a columnar structure grown without changing the particle diameter of the hexagonal crystal particles. This columnar structure was the same even when the thickness of the underlayer increased. In addition, an initial growth layer having no specific structure was observed near the substrate surface.

From the result of observation by TEM, this CoO-
SiO₂It is clear that the surface of the film 22 has irregularities.
won. This unevenness reflects the honeycomb structure,
Are crystal grains, and the concave portions are amorphous portions. Also,
Focusing on one peak (convex), the valley (concave) closest to that peak
Part) with an atomic force electron microscope (AFM).
As a result, the average was 10 nm. This average is
As a result of measuring 500 randomly selected places
And the standard deviation of these measurements is
The minimum value was 0.5 nm or less. Also, with the substrate
The distance between the peak and the valley in the parallel direction was 5 nm. this thing
Indicates that each of the peaks of the unevenness of the underlayer 22 is minute,
This shows that the film as a whole is flat. This Co
O-SiO ₂In the film, crystal grains are regularly arranged in a honeycomb shape.
Lined, and the shape of the unevenness is good and the variation is small.
Therefore, it is useful as a textured substrate. This
The shape of the unevenness depends on the deposition temperature, sputter speed,
By controlling the atmospheric gas pressure
It is possible.

Further, on the underlayer 22, in addition to the fine irregularities reflecting the honeycomb structure, irregularities were observed with a longer period. Therefore, a comparison was made between the unevenness on the substrate and the unevenness of the underlayer having a large period. First, the irregularities of the glass substrate used here were measured by AFM. The measurement was carried out by randomly selecting several squares each having a side of 300 μm, and randomly selecting about 500 squares in each square.
It was carried out about the part. When the distance in the direction parallel to the substrate from one peak (convex portion) to the nearest peak was measured, about 5
The average value at 00 locations was 50 nm. In addition, when the height in a direction perpendicular to the substrate of the valley (concave portion) closest to one peak (convex portion) was measured, the average value at about 500 locations was 60 nm.
Met. According to the same measuring method as that of the substrate, the unevenness of the surface after the formation of the underlayer on the substrate is such that the distance between the peaks in the direction parallel to the substrate is 6 μm and the distance between the peaks and valleys in the direction perpendicular to the substrate is 10 nm. (Lower than the lower limit of AFM measurement).
This unevenness is smaller than the roughness of the substrate surface and indicates that the surface is flat. Here, even if an underlayer is formed on a substrate having even larger irregularities (distance between peaks and valleys in the direction parallel to the substrate: 30 nm, distance between peaks and valleys in the direction perpendicular to the substrate: 100 nm), the irregularities on the surface of the underlayer can be reduced. Was the same as the underlayer on the previous substrate, and the distance between the peaks and the valleys in the direction parallel to the substrate was 6 μm, and the distance between the peaks and the valleys in the direction perpendicular to the substrate was 10 nm or less (the lower limit of AFM measurement). As described above, it was found that a flat surface can be obtained by forming the underlayer by using the ECR sputtering method regardless of the unevenness of the substrate surface.

(3) Formation of Magnetic Layer On the CoO—SiO ₂ film as the underlayer 22, DC
Co ₆₉ Cr _{12 is used} as the magnetic layer 23 by sputtering.
A magnetic layer 23 having a composition of Pt ₁₉ was formed. Ar was used as a discharge gas, and a Co ₆₉ Cr ₁₂ Pt ₁₉ alloy target was used as a target. Gas pressure during sputtering is 3 mTorr, DC power input is 1 kW / 150 mmφ
Met. During the formation of the magnetic layer 23, the substrate 21 is kept at 300 ° C.
Heated. Thus, the magnetic layer 23 has a thickness of 20 nm.
Formed.

(4) Observation of Magnetic Layer by TEM, Analysis by X-ray Diffraction Method and Measurement of Magnetic Properties Co ₆₉ C, which is the magnetic layer 23 obtained as described above,
Observation of the surface structure of the r ₁₂ Pt ₁₉ film by TEM revealed that the structure of the CoO—SiO ₂ film as the underlayer 22 was reflected. That is, Co of the magnetic layer 23 was precipitated as crystal grains on the crystal grains of the underlayer 22, the shape was a regular hexagon, and the particle size distribution was similar to that of the underlayer 22. The average particle size of the magnetic particles was 10 nm, and σ in the particle size distribution was 1.5 nm or less. The appearance of the particle size distribution is almost the same as the value in the underlayer 22 described above, indicating that the magnetic particle size has been reduced and the variation in the particle size has been significantly reduced. Therefore, since there are almost no fine crystal grains, it is possible to form a magnetic disk having excellent heat fluctuation. Observation of the cross-sectional structure showed that the magnetic layer 23 grew from the underlayer 22 with a connection of a crystal lattice and had a columnar structure. Thus, it can be seen that the magnetic particle diameter of the magnetic layer 23 can be controlled by epitaxially growing the magnetic particles of the magnetic layer 23 from the crystal grains of the underlayer 22.

The magnetic layer portion grown on the amorphous region, which is the crystal grain boundary portion, had a different structure from the magnetic particles epitaxially grown on the crystal grains, and no columnar structure was observed. Such a magnetic layer portion has magnetism different from that of the magnetic particle portion, and exhibited semi-hard magnetism. Since the portions having different magnetism separate the magnetic particles with a uniform width, magnetic interaction between the magnetic particles can be reduced. This reduction in magnetic interaction is effective for high-density recording.

As described above, the magnetic layer 23 of Co ₆₉ C
After forming the r ₁₂ Pt ₁₉ alloy film, the structure of the laminate was analyzed by X-ray diffraction. As a result, 2θ = 62.
A diffraction peak was observed at about 5 °, and this peak was due to (220) of CoO in the CoO—SiO ₂ film as the underlayer 22.
It turns out that it corresponds. A diffraction peak is also observed around 2θ = 73 °, and this peak is
_Co 69 _{Cr 1} 2 _{Pt 19} film of Co (11 at.
0). Thus, Co was oriented in a direction suitable for high-density recording because the underlayer 22
This is because the magnetic particles were epitaxially grown from above the middle crystal particles, and the result reflects the orientation of the crystal particles in the underlayer 22. If the magnetic layer is grown without forming the underlayer,
As a result of the same X-ray diffraction analysis, (11.
No (0) plane was observed, and (00.2) of Co was observed. For this reason, the CoO—SiO ₂
It was found that the film greatly contributed to the control of the orientation of Co in the magnetic layer 23.

Next, the Co ₆₉ Cr, which is the magnetic layer 23, is used.
The magnetic properties of the ₁₂ Pt ₁₉ film were measured. The obtained magnetic properties are as follows: coercive force is 3.5 kOe, Isv is 2.5 × 10
^-16 emu, S, which is an index of the squareness of the hysteresis in the MH loop, was 0.85, and S ^† was 0.90, indicating good magnetic properties. This reflects the fact that the magnetic particle diameter of the magnetic layer 23 is small and its variation is small, and furthermore, the result that the magnetic interaction between the magnetic particles is reduced.

(5) Formation of Protective Layer Finally, a carbon film was formed as the protective layer 24 to a thickness of 5 nm by DC sputtering. Ar was used as a sputtering gas. The input DC power density was 1 kW / 150 mmφ, and the gas pressure during sputtering was 5 mTorr. Thus, the magnetic disk 30 having the structure shown in FIG. 7 was formed.

(6) Evaluation of Magnetic Disk Next, a lubricant was applied to the surface of the magnetic disk formed as described above to complete the magnetic disk 30. A plurality of magnetic disks were manufactured by the same process, mounted coaxially on a spindle, and incorporated into a magnetic recording device. The magnetic recording apparatus had the same configuration as that of the first embodiment shown in FIGS. The distance between the magnetic head surface and the magnetic layer was 15 nm. These magnetic disks have 40 Gbits / inc
Evaluation of the disk S / N and record the signal corresponding to h ^2, the reproduction output of 32dB were obtained.

Here, when the magnetization reversal unit was measured by a magnetic force microscope (MFM), two or three magnetic particles were reversed at once with respect to the recording magnetic field for recording 1-bit data. This is a sufficiently small value compared to 5 to 10 conventional magnetization reversal units. At the same time, the zigzag pattern corresponding to the boundary of the magnetization switching region was significantly smaller than that of the conventional medium. In addition, thermal fluctuation and demagnetization due to heat did not occur. This is an effect due to the fineness of the magnetic particles in the magnetic layer and the small variation in the magnetic particle diameter. When the defect rate of the magnetic disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

Here, when the distance between the magnetic head and the surface of the magnetic layer was set to 15 nm, the magnetic head stably floated. However, when a magnetic disk having no underlayer formed by the ECR sputtering method was driven under the same conditions, a stable reproduced signal could not be obtained, or the magnetic head was damaged. The reason for this is that the irregularities formed on the surface of the magnetic disk are so large that the magnetic recording device exceeds the range in which the distance between the magnetic head and the magnetic disk can be controlled to be constant.

In Examples 1, 2, 3, and 5, CoO was used as the crystal particles of the underlayer.
Even when magnesium oxide, iron oxide or nickel oxide was used, hexagonal crystal particles similar to CoO were obtained. Further, although SiO ₂ was used as an oxide constituting the crystal grain boundary portion, other than this, even when aluminum oxide, titanium oxide, tantalum oxide or zinc oxide was used, crystal grains similar to SiO ₂ were uniformly separated. The border was obtained.

In the above Examples 1 to 5, the diameter was 2.5 inc.
h, the size and the material are not limited thereto, and any size may be used.
An alloy or a resin substrate may be used. Also, glass,
A substrate in which a NiP layer is formed on a resin, Al or Al alloy substrate by a plating method may be used.

In the first to fifth embodiments, the example in which the underlayer is formed on the glass substrate has been described. However, the substrate may be formed of the same material as the underlayer, and the formation of the underlayer may be omitted. in this case,
The terms "substrate" and "underlayer" in the claims are to be interpreted as representing the same thing.

In Examples 1 to 5, Ar was used as a sputtering gas when forming the protective layer.
A mixed gas containing nitrogen or hydrogen may be used. When a film is formed using such a mixed gas, nitrogen and hydrogen are contained in the obtained thin film, which can promote the densification of the carbon thin film serving as the protective layer.

[0123]

According to the method for manufacturing a magnetic recording medium of the present invention, the kinetic energies of target particles during film formation are made uniform.
And controllable, the crystal orientation of the magnetic layer,
Structure can be precisely controlled. In particular, when the underlayer is formed using the film forming method according to the present invention and the magnetic layer is epitaxially grown while reflecting the structure of the underlayer, the particle diameter of the magnetic particles can be reduced, and the variation in the particle diameter can be reduced. At the same time, since the magnetic particles can be separated from each other by the non-magnetic portion, the magnetic interaction between the particles can be suppressed, and the unit of magnetization reversal can be reduced. Therefore, a magnetic recording medium with low noise, low thermal fluctuation, and low thermal demagnetization can be manufactured. Further, according to the manufacturing method of the present invention, since the orientation of the magnetic layer can be controlled, a magnetic layer having an orientation suitable for high-density magnetic recording can be formed.

Further, when the film forming method according to the present invention is used, a film having a flat surface can be formed without being affected by rough irregularities on the substrate. Therefore, the magnetic head can run stably. In particular, it is effective for proximity recording where the distance between the head and the medium is 20 nm or less, and is effective for performing ultra-high density magnetic recording.

The carbon film formed by the method of the present invention is a dense thin film having a uniform film thickness without forming an island even if it is an extremely thin film of 5 nm or less, and having high hardness and high hardness. When this carbon film is used as a protective layer on the magnetic layer, it can exhibit a sufficient protective function even though it is an extremely thin film of 5 nm or less, so that the distance between the magnetic head and the magnetic layer can be reduced,
This is effective for improving the recording density. Furthermore, when the ECR sputtering method according to the present invention is used, since the substance diffusion between layers can be suppressed at the time of forming the protective layer, there is also an effect that the magnetic layer is not magnetically damaged.

By combining the above technologies, 40G
The production of a magnetic recording medium capable of ultra-high density magnetic recording exceeding bits / inch ² was realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a cross-sectional structure of a magnetic disk according to a first embodiment.

FIG. 2 is a schematic view showing the surface morphology of an underlayer according to the present invention.

FIG. 3 is an X-ray diffraction profile of an underlayer according to Example 1.

FIG. 4 is an X-ray diffraction profile of an underlayer and a magnetic layer according to Example 1.

FIG. 5 is a schematic configuration diagram of a magnetic recording device that is an example of the present invention.

FIG. 6 is a sectional view of the magnetic recording apparatus taken along line AA ′ of FIG. 5;

FIG. 7 is a schematic diagram illustrating a cross-sectional structure of a magnetic disk according to a fourth embodiment.

FIG. 8 shows an example of a film forming apparatus E used in the method of the present invention.
It is the schematic of the cross section of a CR sputtering apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 21, 68 Substrate 2, 22 Underlayer 3 Control layer 4, 23 Magnetic layer 5, 24 Protective layer 10, 30 Magnetic disk 12 Crystal grain 14 Crystal grain boundary part 51 Rotation drive system 52 Spindle 53 Magnetic head 54 For magnetic head Drive system 60 Magnetic recording device 62, 64, 66 Coil 70 Target 72 Flow of target particles 74 Microwave generator 76 ECR plasma 80 ECR sputtering device 81 First chamber 83 Second chamber 90 Power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruaki Takeuchi 1-1-88 Ushitora, Ibaraki-shi, Osaka Inside Hitachi Maxell Co., Ltd. (72) Tomoko Soya 1-188 Ushitora, Ibaraki-shi, Osaka Hitachi Within Maxell Corporation (72) Inventor Tetsuo Mizumura 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Corporation (72) Koichiro Wakabayashi 1-1-88 Ushitora, Ibaraki City, Osaka Hitachi Maxell (72) Inventor Harumi Sakamoto 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell Co., Ltd. (72) Inventor Tsuyoshi Onuma 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell, Ltd. F term (reference) 5D112 AA03 AA05 AA07 FA04 FB26

Claims (14)

[Claims] 1. A method for manufacturing a magnetic recording medium comprising: a magnetic layer for recording information on a rigid substrate; and a protective layer, comprising: generating a plasma by resonance absorption; The target particles are sputtered by colliding with the target, and a bias voltage is applied between the substrate and the target, whereby the sputtered target particles are deposited on the substrate while being guided, and at least the magnetic layer and the protective layer are deposited. A method for manufacturing a magnetic recording medium, comprising forming one layer. 2. The method according to claim 1, wherein microwaves are used in the resonance absorption. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the bias voltage is applied from a radio frequency AC power supply or a DC power supply. 4. At least one selected from density, surface flatness, crystal orientation, crystal growth direction, crystal structure, and particle diameter of at least one of the magnetic layer and the protective layer formed on the substrate. 4. The method according to claim 1, wherein one of the magnetic recording media is controlled. 5. A magnetic recording medium having an areal recording density of 40
5. The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium exceeds Gbits / inch ² . 6. A method for manufacturing a magnetic recording medium comprising a rigid substrate and an underlayer and a magnetic layer for recording information, comprising: generating a plasma by resonance absorption; The target particles are sputtered by applying a bias voltage between the substrate and the target, whereby the sputtered target particles are deposited while being guided on the substrate to form the underlayer. A method for manufacturing a magnetic recording medium. 7. A method for manufacturing a magnetic recording medium further comprising a protective layer on the magnetic layer, the method comprising: generating plasma by resonance absorption; causing the generated plasma to collide with a target to sputter target particles; 7. The magnetic layer and the protective layer according to claim 6, wherein by applying a bias voltage between the target and the target, the sputtered target particles are deposited while being guided on the substrate to form the magnetic layer and the protective layer. A method for manufacturing a magnetic recording medium. 8. The method according to claim 7, wherein in forming the protective layer, a mixed gas mainly composed of argon and containing at least one of nitrogen and hydrogen is used as a plasma gas. 9. The method for manufacturing a magnetic recording medium according to claim 6, wherein a microwave is used in the resonance absorption. 10. The method for manufacturing a magnetic recording medium according to claim 6, wherein the bias voltage is applied from a radio frequency AC power supply or a DC power supply. 11. The density, surface flatness, crystal orientation, crystal growth orientation, crystal structure, and particle diameter of at least one of an underlayer, a magnetic layer, and a protective layer formed on the substrate. The method for manufacturing a magnetic recording medium according to claim 6, wherein at least one selected one is controlled. 12. The method for manufacturing a magnetic recording medium according to claim 6, wherein the underlayer has two or more layers. 13. The method of manufacturing a magnetic recording medium according to claim 6, wherein said magnetic layer is epitaxially grown from said underlayer. 14. The magnetic recording medium having an areal recording density of 4
The method of manufacturing a magnetic recording medium according to claim 6, wherein the magnetic recording medium has a density exceeding 0 Gbits / inch ² .