JP2000048358A - Manufacturing method of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit stable running of a head and to enhance S-N ratio in high density recording by forming an underlayer comprising Cr, Mo, W, Nb, Ta or an alloy based on these in a specified thickness between a nonmagnetic disk substrate and a magnetic layer. SOLUTION: An underlayer comprising Cr, Mo, W, Nb, Ta or an alloy based on these is formed in 5-500 nm thickness on a substrate and crystals are grown under orientation so that the (100) or (110) crystal lattice faces of the underlayer are made parallel to the substrate to enhance magnetic anisotropy in the running direction of a head. A magnetic layer preferably comprises Co, Fe, Ni or an alloy based on these and it is preferable that crystals are grown under orientation so that the (110) crystal lattice faces of the magnetic layer are made almost parallel to the substrate because magnetic anisotropy is enhanced by the growth. When a layer of a carbide such as WC or (W-Mo)C is used as a protective layer, sliding and corrosion resistances can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic drum, a magnetic tape, a magnetic disk, and a magnetic card and a magnetic recording apparatus, and more particularly to a thin film medium suitable for high-density magnetic recording and magnetic recording using the same. Related to the device.

[0002]

2. Description of the Related Art In recent years, as electronic computers have become smaller and faster, there has been an increasing demand for large-capacity and high-speed access to magnetic disk devices and other external storage devices.
In particular, a magnetic disk recording device is an information storage device suitable for high-density and high-speed operation, and the demand for it is increasing. Recording media used in magnetic disk devices include:
A medium in which a powder of an oxide magnetic material is applied on a substrate and a thin film medium in which a thin film of a metal magnetic material is sputter-deposited on a substrate have been developed. This thin film medium is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-78.
As described in JP-A No. 06 and JP-A-60-111323, the density of the magnetic substance contained in the magnetic recording layer is higher than that of the coating type medium, and thus it is suitable for high-density recording and reproduction.

Further, an MR head has been developed in which the reproducing sensitivity is improved from that of a conventional inductive magnetic head by using a magnetoresistive effect (hereinafter abbreviated as MR) element in a reproducing section of the magnetic head (refer to FIG. 1). For example, Japanese Patent Application Laid-Open No. 62-4061
0 and JP-A-63-117309). If this head is used, a sufficient signal S / N can be obtained even if the area of the recording bit is small, so that the recording density of the medium can be dramatically improved.

[0004] Aluminum alloy, glass,
Ceramics or organic resins are used. Also,
On the surface of the disk substrate, for example, a Ni-P plating layer or an anodic oxide film having a thickness of about 10 [mu] m is formed for the purpose of improving workability such as hardness and smoothness or improving magnetic properties. On such a substrate surface, Japanese Patent No. 4735840,
-29418, JP-A-62-146434, JP-A-63-121123, magazine IEEE Trans. Magn., Vol.
MAG-22 (5), p.579, 1986, or IEEE Tra
ns. Magn., vol. MAG-23 (5), p. 3405 A fine groove may be formed in a substantially magnetic head running direction, for example, a substantially circumferential direction, as described in 1987. This groove is called a texture, and is formed by cutting the surface in a substantially circumferential direction using abrasive grains, and the center line average roughness (Ra) of the groove has conventionally been in the range of about 2 nm to 10 nm. By forming such a texture, the frictional force when the magnetic head comes into contact with the medium is reduced, and the problem of the head sticking to the medium surface during a contact start / stop (hereinafter abbreviated as CSS) operation is avoided. When the center line average roughness of the groove, the thickness of the base film, or the film forming conditions of the medium are optimized, the magnetic properties of the magnetic film measured by applying a magnetic field in the running direction of the magnetic head, such as the coercive force Hc, Magnetization Br, coercivity squareness ratio S *, or magnetic anisotropy energy K measured by applying a magnetic field in the substrate and rotating the sample in the substrate surface are improved as compared with the case where no texture is formed. In some cases, the S / N and resolution during recording and reproduction are improved. Furthermore, there is a problem called modulation, in which the magnetic properties in the substantially circumferential direction become non-uniform in the medium surface due to the heating temperature and the transport method at the time of forming the medium, and the reproduction output fluctuates in the medium surface. However, when the depth of the groove, the composition of the base film, the film forming conditions, and the like are optimized, the magnetic properties in the substantially circumferential direction are uniformed in the medium surface, and as a result, the effect of suppressing the modulation has been recognized. .

[0005]

In order to improve the recording density of a thin film medium, it is necessary to minimize the gap between the magnetic head and the recording medium shown in FIG. is important. This is because a steep magnetic field distribution is formed in the medium at the time of recording, and a magnetic flux from the medium can be detected with high sensitivity at the time of reproduction, and loss of the reproduction output can be suppressed. However, when the flying height of the head is reduced in a texture-processed medium, the frequency of contact of the magnetic head with the medium increases as compared to a smooth substrate having no texture. Detailed studies have revealed that this is because irregularities and fine projections are inevitably formed on the medium surface by texture processing, and the projections come into contact with the magnetic head when the flying height is reduced.
On the other hand, as a method for reducing the frequency of contact between the head and the medium, Japanese Patent Laid-Open No. 1-162229 discloses that projections on the substrate surface are removed by a polishing step. However, in this case, the magnetic properties and anisotropic energy of the magnetic film measured by applying a magnetic field in the head running direction are lower than before the protrusion is polished, and the S / N at the time of recording / reproduction is reduced. There was a problem that modulation occurred.

Further, when the depth of the groove is large, the head needs to follow a track on which information is recorded,
The uniformity and S / N of the servo signal recorded on the medium in advance
There was also a problem that the track density could not be increased because it was worse than a smooth substrate without texture.

To solve the problems of head flying characteristics and servo signal deterioration, it is effective to reduce the depth of the groove. However, the magazine IEEE Trans. Magn., Vol. MAG-23 (5), p. 34
05 As described in 1987, when the depth of the groove is reduced, there is a problem that the magnetic characteristics of the magnetic film measured by applying a magnetic field in the head traveling direction are deteriorated. Here, the coercive force Hc (θ) measured by applying a magnetic field in the running direction of the magnetic head
And the coercive force Hc (r) measured by applying a magnetic field in a direction substantially perpendicular to the running direction of the magnetic head in the plane of the substrate, and (Hc
(θ) −Hc (r) / Hc (θ) + Hc (r)) defines the orientation ratio of the coercive force Hc in the running direction of the magnetic head.

The Hc orientation ratio is closely related to the recording / reproducing characteristics of the medium. As a result of detailed experiments, the linear recording density was 5
0 kBPI (BPI = abbreviation of Bits Per Inch), track density 3 kTPI (TPI = Tracks
In order to obtain a reproduction signal S / N of 4 or more at the time of Per Inch (abbreviation of Per Inch), it was found that the orientation ratio of Hc is preferably 0.1 or more and 0.7 or less. Further, the in-plane magnetic anisotropy energy measured by applying a magnetic field to the substrate and rotating the sample within the substrate is 3 × 10 ⁴ J / m ³ or more and 5 × 10 ⁴ J / m ³ or more.
It has been found that the content is preferably ⁵ J / m ³ or less. However, it is not known in the prior art to reduce the size of the groove to control the orientation ratio of Hc within the above range, and the center line average roughness Ra of the groove needs to exceed 3 nm.

In view of the above problems and circumstances, it is a first object of the present invention to provide a medium capable of running a head stably, having high magnetic characteristics in the head running direction, and having a high S / N during high-density recording. It is to provide. That is, when the flying height of the head is 0.1 μm or less, the number of bit errors after 50,000 head seek tests from the inner circumference to the outer circumference is 10 bits / surface or less, the medium modulation is 10% or less, the linear recording density is 50 kBPI, and the track density is An object of the present invention is to provide a magnetic recording medium in which the value of S / N of a reproduced signal at 3 kTPI is 4 or more. Further, a second object is to provide a method for producing such a medium with good reproducibility, and a third object is to
An object of the present invention is to provide a large-capacity and highly reliable magnetic recording apparatus using such a medium.

[0010]

Means for Solving the Problems The present inventors have studied the fine surface shape of a medium, the magnetic characteristics measured by applying a magnetic field in the head running direction, the in-plane magnetic anisotropic energy, the recording / reproducing characteristics, and the head floating. As a result of diligent research into the relationship between the magnetic properties and the in-plane magnetic properties, the above-mentioned object can be achieved by having extremely fine irregularities in the running direction of the head on the medium surface. It has been found that a medium excellent in anisotropic energy and stable flying characteristics of a head can be provided. That is, the center line average roughness Ra of the medium surface measured in a direction substantially perpendicular to the running direction of the magnetic head
It has been found that the range of (r) is 0.3 nm or more and 3 nm or less, and it is possible to provide a medium in which the orientation ratio of Hc is 0.1 or more and 0.7 or less. The surface center line average roughness R measured in a direction substantially perpendicular to the running direction of the magnetic head
The range of a (r) is not less than 0.3 nm and not more than 3 nm, has an axis of easy magnetization in the head running direction, and applies a magnetic field to the substrate surface to rotate the sample in the substrate surface. Anisotropic energy is 3 × 10 ⁴ J / m ³ or more and 5 × 10 ⁵ J / m ³
It has been found that the following media can be provided. At this time,
A distance of 1 μm on the medium surface in a direction substantially perpendicular to the head running direction
It is preferable that the average number of grooves having a depth of 1 nm or more present around 0.5 or more and 100 or less. Further, the range of the value of the ratio Rmax (r) / Ra (r) between the maximum height Rmax (r) and Ra (r) of the medium surface is preferably 10 or more and 30 or less. Also, the ratio of the center line average roughness Ra (θ) measured in the substantially magnetic head running direction to the center line average roughness Ra (r) measured in a direction substantially perpendicular thereto, Ra (r)
/ Ra (θ) is preferably 1.1 or more and 3.0 or less.

Here, the use of "center line average roughness" and "maximum height" is based on the definition prescribed in Japanese Industrial Standards (JIS-B0601). The center line average roughness and the maximum height can be measured by, for example, a stylus or optical surface roughness meter, a scanning tunneling electron microscope, an atomic force microscope, a three-dimensional scanning electron microscope, or a transmission electron microscope. . In order to obtain a measurement result with good reproducibility when using a stylus type surface roughness meter, the tip diameter of the stylus as shown in FIG. 2 should be 0.5 μm or less, preferably 0.2 μm or less. Pressing load of 4mg or less and scanning speed of stylus 1μ
m / s or less, and the cutoff is preferably 0.5 μm or more and 5 μm or less. When a part of the protective film is processed by etching, heating, or the like, the shape of the groove can be measured by scanning the surface of the unprocessed portion with a stylus as shown in FIG. If the surface of the magnetic film is processed, it is preferable to measure only the roughness of the magnetic film surface by removing only the protective film by etching.

An underlayer made of Cr, Mo, W or an alloy containing these as main components is formed on a substrate to a thickness of 5 n.
(100) or (11)
0) It is preferable to grow the crystal so that the crystal lattice plane is parallel to the substrate, because the magnetic anisotropy in the head running direction can be improved. For the magnetic layer, Co, Fe, Ni or an alloy containing these as main components is desirable.
Ni, Co-Cr, Co-Fe, Co-Mo, Co-
Good magnetic properties are observed when alloys such as W, Co-Pt, and Co-Re are the main components. In addition, the magnetic layer
It is preferable that the crystal is oriented and grown so that the (110) crystal lattice plane is substantially parallel to the substrate, since magnetic anisotropy is improved. When excellent corrosion resistance and magnetic properties are required, Cr, Mo, or W is used as a main component for the underlayer, and N
b, Ti, Ta, Pt, Pd, an alloy to which any of Si, Fe, V or P is added, and Co-Ni-Zr, Co-Cr as a magnetic material constituting the magnetic film
It is desirable to use an alloy containing -Pt, Co-Cr-Ta, and Co-Ni-Cr as main components. The magnetic film is made of Cr, Mo, W, V, Ta, Nb, Zr, Ti, B,
It is preferable to use a non-magnetic intermediate layer containing at least one of Be, C, and Ni-P as a main component to reduce the medium noise to two or more layers. Furthermore, by forming carbon as a protective layer of a magnetic film with a film thickness of 10 nm to 50 nm, and further providing a lubricating layer of an adsorbent perfluoroalkyl polyether or the like with a film thickness of 3 nm to 20 nm, high reliability and high density recording are possible. A magnetic recording medium can be obtained. Further, WC as a protective layer, (W-Mo) carbides such as C, (Zr-Nb) -N, Si 3 N nitrides such _4, Si
Oxides such as O ₂ and ZrO ₂ , or B, B ₄ C and Mo
It is preferable to use S ₂ , Rh, or the like because sliding resistance and corrosion resistance can be improved. In particular, these protective films are subjected to plasma etching using a fine mask after film formation to form fine irregularities on the surface, to form projections on the protective film surface using a compound or mixture target, or to perform heat treatment. By forming unevenness on the surface, the contact area between the head and the medium can be reduced, and the problem of the head sticking to the medium surface during the CSS operation is preferably avoided. In forming the magnetic recording medium, the center line average surface roughness R
a is a non-magnetic substrate having a diameter of 2 nm or less;
Preferably, the grooves are formed by polishing in a substantially magnetic head running direction with an abrasive containing abrasive grains of 0.5 μm or less, and then a magnetic layer and a protective layer are formed directly by physical vapor deposition means or via an underlayer. If the range of the surface center line average roughness Ra (r) measured in a direction substantially perpendicular to the running direction of the magnetic head is not less than 0.3 nm and not more than 3 nm, the number of bit errors in the flying height of the head of 0.1 μm or less is reduced. It is preferable because it can be reduced. Further, as another method for forming the magnetic recording medium, a base film formed on a non-magnetic substrate and having a center line average surface roughness Ra of 2 nm or less may be coated with an average particle diameter of 1 μm or less.
Preferably, the grooves are formed as shown in FIG. 2 by polishing substantially in the running direction of the magnetic head with an abrasive containing abrasive grains of 0.5 μm or less, and then the magnetic layer and the protective layer are formed by physical vapor deposition means. The range of surface center line average roughness Ra (r) measured in a direction substantially perpendicular to the running direction of the magnetic head is 0.3 nm.
As described above, the thickness can be set to 3 nm or less. At this time, it is important to optimally control the polishing processing time by the abrasive grains without making the polishing processing time excessively short or long. It is also effective to form the grooves so as to cross each other. This makes it possible to reduce the average number of grooves having a depth of 1 nm or more per 1 μm in a direction substantially perpendicular to the head running direction to 0.5.
More than 100 and less than 100 can be used. Also,
The range of the value of Rmax (r) / Ra (r) can be set to 10 or more and 30 or less. Also, Ra (r) / Ra (θ)
Can be set to 1.1 or more and 3.0 or less, and these effects improve the degree of orientation of Hc and the in-plane magnetic anisotropy energy.

The magnetic recording medium of the present invention has a very small fluctuation of the servo signal due to the unevenness of the surface of the magnetic film and is of high quality, so that the positioning accuracy of the head is improved. Also, M
By combining a magnetic head having an R element and a track width of 5 μm or less, the linear recording density of the medium is reduced to 50 kBPI.
As described above, it is possible to provide a large-capacity, high-reliability magnetic recording device having a recording track density of 3 kTPI or more.

The present inventors set the average particle size to 0.1 to 10 μm.
Ni-P plating Al using liquid or tape-like processing material containing diamond, alumina, ceria abrasive grains
Alloys, glass, Ti, Si, carbon, ZrO ₂ etc.
A non-magnetic substrate having a surface center line average roughness of about 1 nm or less is polished by changing the polishing pressure, time, polishing method, etc., and a fine groove is provided in the head running direction. A film, a protective lubricating film, and the like were formed, and the levitation, magnetic characteristics, and recording / reproducing characteristics were examined. Further, a Cr underlayer is formed on a nonmagnetic substrate having a surface center line average roughness Ra of about 1 nm,
The surface was polished under the above polishing conditions to form fine grooves in the head running direction, and a magnetic film, a protective lubricating film, and the like were formed thereon, and flying characteristics, magnetic characteristics, recording / reproducing characteristics, etc. were examined. As a result, conventionally, in order to increase the magnetic anisotropy in the circumferential direction, it was necessary to increase the Ra of the groove to a large value exceeding 3 nm even at the expense of the flying property of the head. The present inventors have found that even when the roughness of the groove appearing on the surface of the magnetic film is reduced, it is possible to provide a medium having excellent magnetic anisotropy in the head running direction and further excellent flying property. This is due to the operation described below. That is, the average particle size of the processing abrasive grains is 1 μm or less, preferably 0.1 μm.
When the Ra (r) of the magnetic film surface is controlled by the abrasive grain processing time and the abrasive grain processing pressure while controlling the grain size to 5 μm or less, the head traveling direction of the coercive force in the range of 0.3 nm ≦ Ra ≦ 3 nm as shown in FIG. Is improved to 0.1 or more and 0.7 or less. On the other hand, when Ra exceeds 3 nm, the magnetic anisotropy in the head traveling direction and the head flying property decrease. The reason why a high coercive force orientation ratio can be obtained even with a medium having such a small roughness and a fine groove is that the cutting ability of abrasive grains during polishing is most excellent in the initial stage of processing, and the groove density is high. This is because When texture processing is performed on a smooth substrate having a center line average roughness of 1 nm, Ra (r) in a direction substantially perpendicular to the head traveling direction increases remarkably as the processing time increases, as shown in FIG. The change of the surface roughness Ra (θ) is slower than that of Ra (r). As described above, the abrasive grains most effectively act on the polishing in the initial processing time region in which Ra (r) changes abruptly. At this time, a good groove having a high density and a size of about a crystal grain is formed. You. By doing so, the average number of grooves having a depth of 1 nm or more and existing at a distance of 1 μm in a direction substantially perpendicular to the head traveling direction can be set to 0.5 or more and 100 or less. Also, Rm
The value range of ax (r) / Ra (r) can be set to 10 or more and 30 or less. Further, the range of the value of Ra (r) / Ra (θ) can be set to 1.1 or more and 3.0 or less, and by these effects, the degree of orientation of Hc and the in-plane magnetic anisotropy energy are reduced. improves. As in the past, if the processing time is extended by using a large abrasive grain size, abnormal protrusions or burrs appear on the medium surface, leading to a decrease in head buoyancy, and the degree of orientation of Hc and in-plane magnetic anisotropy energy are reduced. descend.

Further, when the crystal is oriented and grown so that the (110) crystal lattice plane of the magnetic layer is substantially parallel to the substrate, the orientation ratio in the head running direction and the in-plane magnetic anisotropy energy are improved, and the underlying film is formed. In the case where the magnetic film is provided, it is preferable to perform the orientation growth so that the (100) or (110) crystal lattice plane is substantially parallel to the substrate because the orientation growth of the magnetic film is promoted. Further, the magnetic film of the medium is made of Cr, Mo, W, V, Ta, N
When a multilayer is formed by a non-magnetic intermediate layer containing at least one of b, Zr, Ti, B, Be, C, and Ni-P as a main component, the thickness of one layer becomes small, and the sum of medium noise from each layer becomes a single layer. Significantly smaller than the noise of the magnetic film of
When a magnetic head having an R reproducing element is used, the S
/ N is preferred because the ratio of N / N is significantly improved. In the medium according to the present invention, the fluctuation of the magnetization in the magnetization transition region is extremely small, so that the medium noise is small and the track width is 5 μm.
50k when recording / reproducing with the following high recording magnetic head
At a high recording density of BPI or higher, a large-capacity magnetic recording apparatus having an S / N of 4 or higher and an overwrite (O / W) characteristic of 26 dB or higher can be obtained. In particular, the unevenness of the surface of the magnetic film is smaller than before, so that the quality of the servo signal is high even at a high recording density of 3 kTPI or more, and good head positioning can be performed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. FIG. 5 schematically shows a cross-sectional structure of the thin film medium according to the present invention. In the figure, reference numeral 51 denotes an Al-Mg alloy, chemically strengthened glass, organic resin,
Substrates made of Ti, Si, carbon, ceramics, or the like;
This is a nonmagnetic plating layer made of iP, Ni-WP, or the like. When an Al-Mg alloy is used as a substrate,
A substrate provided with such a plating layer is used as a substrate. 53 and 53 ′ are Cr, Mo, W, or a metal base film made of an alloy containing any of these as a main component;
54 and 54 'are Co-N layers formed on the underlying film.
i, Co-Cr, Co-Re, Co-Pt, Co-P,
Co-Fe, Co-Ni-Zr, Co-Cr-Pt-
B, Co-Cr-Al, Co-Cr-Ta, Co-Cr
-Pt, Co-Ni-Cr, Co-Cr-Nb, Co-
Ni-P, Co-Ni- Pt, metallic magnetic layer made of Co-Cr-Si or the like, carbon 55 and 55 'are formed on the said magnetic film, _{boron, B 4 C, SiC, SiO} 2,
Non-magnetic protective films made of Si ₃ N ₄ , WC, (W-Mo) C, (W-Zr) C and the like are shown, respectively.

<Example 1> Outer diameter 95 mm, inner diameter 25 m
m, 0.8 mm thick Al-4Mg (the number in front of the atomic symbol indicates the content of the material; the unit of the content is% by weight). The layer was formed to have a thickness of 13 μm. The surface of this non-magnetic substrate was polished smoothly using a lapping machine until the surface center line average roughness Ra became 2 nm, washed, and further dried. Thereafter, by using a tape polishing machine (for example, described in JP-A-62-262227), a polishing tape is passed through a contact roll in the presence of abrasive grains, and pressed against both sides of the disk surface while rotating the disk substrate 51. A substantially circumferential texture was formed on the disk substrate surface. At this time, by controlling the average particle diameter of the abrasive grains, the processing time, and the pressure for pressing the polishing tape with the contact roll, the Ra of the medium surface is controlled.
(r) was changed. Further, dirt such as an abrasive adhered to the substrate was washed and removed, and dried. The disk substrate thus formed is placed in a magnetron sputtering apparatus for 2 hours.
The temperature was raised to 50 ° C. in a vacuum to form a 50 nm-thick Cr underlayer under the conditions of an argon pressure of 2 mTorr.
86Co-10Cr-4Ta (atomic%)
A 30 nm-thick metal magnetic film made of Thereafter, a carbon protective film having a thickness of 30 nm was formed on the magnetic film, and finally a lubricating layer made of adsorbable perfluoroalkyl polyether was formed on the protective film. The magnetic recording medium thus formed was analyzed by X-ray diffraction.
In the underlayer, crystals were oriented and grown so that the (100) or (110) crystal plane was substantially parallel to the substrate. In the magnetic layer, the (110) plane was oriented and grown so as to be substantially parallel to the substrate.

The center line average roughness Ra (θ) measured in the running direction of the magnetic head on the surface of the medium thus formed and the center line average roughness Ra (r) measured in a direction perpendicular to the center line are 0.2 μm in diameter. Using a stylus type surface roughness meter. At this time, the pressing load of the stylus was 4 mg, and the stylus scanning speed was 1 μm.
m / s, and the cutoff was 4.5 μm. Further, the relative velocity of the head medium is 12 m / s, and the flying spacing is 0.08.
In μm, a head seek test from the inner circumference to the outer circumference was performed using an effective gap length of 0.4 μm, a track width of 5 μm, and a read / write separated thin film magnetic head using an MR element.
Number of bit errors after 10,000 times, modulation (Md), linear recording density 50 kBPI, track density 3 kTPI
The value of S / N of the reproduced signal at the time of was obtained. Here, the modulation Md is defined as Md = (HL) / (H + L) by the maximum output H and the minimum output L in the disk surface. The coercive force Hc (θ) when a magnetic field is applied in the running direction of the magnetic head by a vibrating magnetometer (VSM) or a non-destructive magnetometer with a maximum applied magnetic field of 14 kOe.
And a coercive force Hc (r) when a magnetic field was applied in a direction substantially perpendicular to the running direction of the magnetic head in the plane of the substrate. The in-plane magnetic anisotropy energy K was determined by applying a magnetic field within the substrate surface and rotating the sample within the substrate surface using a torque meter with a maximum applied magnetic field of 14 kOe.

As shown in FIG. 3, a texture is formed using abrasive grains having an average particle diameter of 1 μm or less, as compared with a conventional example in which the center line average roughness Ra (r) of the medium surface exceeds 3 nm. The medium with 0.3 nm ≦ Ra (r) ≦ 3 nm had a remarkably high coercive force orientation ratio of 0.1 or more and 0.7 or less. Further, as shown in FIG. 6, a texture is formed using abrasive grains having an average particle diameter of 1 μm or less, and the surface roughness is reduced to 0.3 as compared with a conventional example having a center line average roughness Ra (r) of more than 3 nm.
The medium in which nm ≦ Ra (r) ≦ 3 nm has an in-plane magnetic anisotropy energy K of 3 × 10 ⁴ J / m ³ or more and 5 × 10 ⁵ J /.
m ³ was below the high. The average number of grooves having a depth of 1 nm or more and present at a distance of 1 μm in a direction substantially perpendicular to the head running direction of the medium having such fine grooves is 0.5 or more, 100 or less, and Rmax (r) The range of the value of / Ra (r) is 10 or more and 30 or less, and further, Ra (r) / Ra (θ)
Range was 1.1 or more and 3.0 or less. Further, at a head flying height of 0.08 μm, the number of bit errors after 50,000 times of the head seek test from the inner circumference to the outer circumference is 10 bits / surface or less, the modulation Md of the medium is 10% or less,
When the linear recording density was 50 kBPI and the track density was 3 kTPI, the S / N value was 4 or more. On the other hand, Ra (r) is 3n
m or more of the conventional magnetic recording medium, the head levitation is inferior,
At a head flying height of 0.08 μm, the number of bit errors after 50,000 head seek tests was 15 bits / surface or more.

Using a substrate on which similar fine grooves were formed, a base film made of Cr, Mo, W, Nb, Ta or an alloy containing these as main components was formed with a film thickness of 5 nm or more and 500 nm or less. Similar surface roughness,
Magnetic anisotropy and recording / reproducing characteristics were obtained. Further, as shown in FIG. 2, the magnetic film is made of Cr, Mo, W, V, Ta, N
When a non-magnetic intermediate layer containing at least one of b, Zr, Ti, B, Be, C, and Ni-P as a main component is formed into two or more layers, noise from the medium is a single-layer magnetic layer. It was reduced by 30% as compared with the case where the film was used, and an S / N value of 5 or more was obtained.

<Embodiment 2> Using the same apparatus as in Embodiment 1, the average grain size of the abrasive grains used for forming the texture was set to 0.5 μm, and a polishing tape was applied with a processing time, a processing direction, and a contact roll. By controlling the pressure to be applied, Ra (r) on the medium surface is set to 0.5 μm or more and 1.0 μm or more.
m or less, and the average number N of grooves having a depth of 1 nm or more per 1 μm in the direction perpendicular to the head running direction on the medium surface.
Was changed. The relationship between the average number N of grooves, the coercive force orientation ratio, and the in-plane magnetic anisotropy energy K is shown in FIG.
Shown in When N is 0.5 or more and 100 or less, the orientation ratio is 0.1.
It was 5 or more and 0.7 or less, and the in-plane magnetic anisotropy energy was 4 × 10 ⁴ J / m ³ or more and 5 × 10 ⁵ J / m ³ or less. Rmax (r) / Ra of the medium having such fine grooves formed thereon
The range of the value of (r) is 10 or more and 30 or less, and Ra (r) / Ra
The range of the value of (θ) was 1.1 or more and 3.0 or less. Further, when the head flying height is 0.08 μm, the number of bit errors after 50,000 times of the head seek test from the inner circumference to the outer circumference is 10
Bit / surface or less, medium modulation is 10% or less, linear recording density 50 kBPI, track density 3 kT
The value of S / N at the time of PI was 4 or more.

<Embodiment 3> Outer diameter 65 mm, inner diameter 20 m
m, a thickness of 0.4 mm, a surface roughness of 1 nm on both surfaces of a glass disk substrate, the same sputtering apparatus as in Example 1,
Depending on the conditions and conditions, as shown in FIG.
An underlayer was formed. Further, the surface of the Cr underlayer was polished with a polishing tape containing an abrasive having an average grain diameter of 1 μm or less in a vacuum chamber to form a texture in a substantially circumferential direction.
The Ra on the surface of the Cr underlayer was 0.8 nm, and the average number N of grooves was 0.7. On this, 90Cr-1 having a thickness of 50 nm is formed.
0Ti (atomic%) base film is formed, and the film thickness is further reduced to 15 nm.
84Co-12Cr-4Pt (atomic%) magnetic film, a 2.5 nm thick Cr intermediate film, and a 15 nm thick 84C
An o-12Cr-4Ta (atomic%) magnetic film was formed. Thereafter, a carbon protective film having a thickness of 30 nm was formed. Further, the average distance of the opening is 50 μm on the surface of the carbon protective film.
An etching mask of not less than m and not more than 100 μm was provided, and the carbon protective film in a region not covered by the mask was etched by oxygen plasma etching to a depth of 15 nm. As a result, as shown in FIG.
Island-like irregularities of 0 μm or more and 100 μm or less were formed. Finally, a lubricating layer such as an adsorbent perfluoroalkyl polyether was formed on the protective film. The center line average roughness Ra (r) on the island portion of the protective film of this medium is 1.0 nm, and the in-plane magnetic anisotropy energy K is 3.5 × 10 ⁴ J / m ^3.
Met. In addition, a distance 1 in a direction substantially perpendicular to the head traveling direction 1
The average number of grooves having a depth of 1 nm or more existing per μm is 0.7, the value of Rmax (r) / Ra (r) is 12, and the value of Ra (r) / Ra (θ) is 1 .6. Also,
At a flying height of the head of 0.1 μm, the number of bit errors after 50,000 times of the head seek test from the inner circumference to the outer circumference is 10 bits / surface or less, the modulation Md of the medium is 10% or less, the linear recording density is 90 kBPI, and the track density is 4 kTPI.
The value of S / N at the time of was 4.5. In the load / unload system in which the head does not come in contact with the medium when the medium stops, the medium exhibited the same sliding resistance as the medium described in Embodiment 1, but the head was lifted up by the CSS system. In this case, the adhesion of the head could be reduced as compared with the medium of Example 1, and the reliability was improved.

Example 4 Similar to Example 1, a fine texture was formed on a disk substrate using abrasive grains having an average diameter of 1 μm or less. At this time, by controlling the processing time for forming the texture on the disk substrate and the pressure for pressing the polishing tape with the contact roll, the center line average roughness Ra (θ) measured in the head running direction and the The ratio to the center line average roughness Ra (r) measured in the perpendicular direction, Ra (r) / Ra (θ), was changed. Further, a magnetic film and a protective film were formed on the substrate. Then, in the same manner as in Example 3, an average diameter of 5 μm or more and 10 μm was formed on the protective film.
m or less, island-shaped irregularities having a height of 10 nm were formed. After measuring the magnetic anisotropy, head flying property, and recording / reproducing characteristics of the medium, the protective film was removed by oxygen plasma etching, and Ra (r) / Ra (θ) on the surface of the magnetic film was measured. At this time, Ra
(r) was not less than 0.5 nm and not more than 3 nm. Ra (r) /
FIG. 8 shows the relationship between Ra (θ) and the in-plane anisotropy energy K. When Ra (r) / Ra (θ) is 1.1 or more and 3.0 or less, the in-plane magnetic anisotropy energy K is 3 × 10 ⁴ J / m ³ or more and 5 × 10 ⁵ J / m ^3. It was higher than below. Further, the average number of grooves having a depth of 1 nm or more and existing at a distance of 1 μm in a direction substantially perpendicular to the head traveling direction of the medium is 0.5 or more,
100 or less, and the range of values of Rmax (r) / Ra (r) was 10 or more and 30 or less. Also, at a head flying height of 0.06 μm, the number of bit errors after 50,000 times of the head seek test from the inner circumference to the outer circumference is 10 bits / surface or less, the medium modulation is 10% or less, the linear recording density is 50 kBPI, and the track density is 3 kTPI. The value of S / N at the time of was 4 or more.

<Example 5> As in Example 1, the average particle size of the abrasive grains used for forming the texture on the disk substrate, the processing time, and the pressure for pressing the polishing tape with the contact roll were changed. Of the medium surface
Table 1 shows the number of bit errors, modulation and S / N when (r) and Rmax (r) / Ra (r) were changed.

[0025]

[Table 1]

According to Table 1, Ra (r) on the medium surface is 0.3 nm.
By setting Rmax (r) / Ra (r) to be 10 or more and 30 or less as well as 3 nm or less, the medium of the present embodiment has a smaller number of bit errors and modulation M than the comparative example.
d was small, the in-plane anisotropy energy and S / N were high, the number of bit errors was 10 bits / plane or less, the modulation was 10% or less, and the S / N was 4 or more. At this time, the ratio of Ra (r) / Ra (θ) is not less than 1.1 and not more than 3.0, and the average of grooves having a depth of 1 nm or more, which are present per 1 μm in a direction substantially perpendicular to the head running direction of the medium. The number was not less than 0.5 and not more than 100.

<Embodiment 6> Using the four magnetic recording media shown in Embodiment 3, a Co-Ta-Zr alloy as a recording magnetic pole material, and a composite thin film magnetic element having a magnetoresistive element in a reproducing section. A magnetic recording device having seven heads was fabricated. This apparatus includes components such as a magnetic recording medium 91, a magnetic recording medium driving unit 92, a magnetic head 93, a magnetic head driving unit 96, and a recording / reproducing signal processing system 95 as shown in FIG. Using this magnetic recording device, spacing
When the average time until an error occurred at 08 μm was determined, it was proved that the lifetime was at least 10 times longer than that of the magnetic recording apparatus using the recording medium of the comparative example, and the reliability was extremely high. In addition, the magnetic recording device prototyped in this example has a low head flying height, has a wide phase margin in recording and reproducing signals, and has a high quality servo signal to improve head positioning accuracy. Twice as high as with the example media,
A small, large-capacity magnetic recording device could be provided. When reproduced with an MR head having a track width of 5 μm or less using this apparatus, the S at high recording density of 90 kBPI and 4 kTPI
/ N was 4 or more, and a large capacity magnetic recording apparatus having an overwrite (O / W) characteristic of 26 dB or more was obtained.

In this embodiment, Co-Ta-Zr is used for recording.
The case where a thin-film magnetic head using an alloy as a magnetic pole material has been described, but a recording / reproducing separation type thin-film magnetic head using a Ni-Fe, Co-Fe alloy or the like as a recording magnetic pole material, a Co-Ta-
Similar effects can be obtained when a metal-in-gap (MIG) recording / reproducing separation composite magnetic head, inductive type thin film head or MIG head having Zr, Fe-Al-Si alloy or the like provided in the gap portion is used. It was confirmed.

[0029]

According to the present invention, it is possible to provide a magnetic recording medium capable of high-density recording and a small and large-capacity magnetic recording apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a diagram showing a longitudinal sectional structure of a thin-film magnetic recording medium according to one embodiment of the present invention, and a relationship between the medium and an MR head.

FIG. 2 is a diagram showing a longitudinal sectional structure of a thin-film magnetic recording medium according to one embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the center line average roughness of the medium surface and the degree of orientation of the coercive force according to one embodiment of the present invention.

FIG. 4 is a diagram illustrating a relationship between a head running direction on a medium surface and a center line average roughness measured in a direction perpendicular to the head running direction and a texture processing time according to an embodiment of the present invention.

FIG. 5 is a diagram showing a longitudinal sectional structure of a medium according to an embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the center line average roughness of the medium surface and the in-plane magnetic anisotropy energy of one embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the average number density of grooves on the medium surface, the orientation ratio of coercive force, and the in-plane anisotropic energy according to one embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between the ratio of the center line average roughness measured in the head running direction and the direction perpendicular to the head running direction on the surface of the magnetic film and the in-plane magnetic anisotropic energy according to one embodiment of the present invention.

FIG. 9 is a longitudinal sectional structural view of a magnetic recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

Reference numeral 11: a magnetic head having an MR reproducing element, 12: a protective film, 13: a metal magnetic film, 14: a metal base film, 15: a non-magnetic plating film, 16: a texture groove, 17: a magnetic disk substrate, 20: a stylus, Reference numeral 21: protective film, 22: metal magnetic film, 23: non-magnetic intermediate film, 24: upper metal base film, 25
... lower metal base film, 26 ... texture groove, 27 ... glass disk substrate, 28 ... protective film island part, 29 ... protective film etching part, 51 ... magnetic disk substrate, 52, 52 '...
Non-magnetic plating layer, 53, 53 '... metal base film, 54, 5
4 ′: metal magnetic film, 55, 55 ′: non-magnetic protective film, 91
... magnetic recording medium, 92 ... magnetic recording medium drive unit, 93 ... magnetic head, 94 ... magnetic head drive unit, 95 ... recording / reproducing signal processing system.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Shiroishi 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Masatoshi Takeshita 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Hitachi, Ltd. Within the Central Research Laboratory (72) Inventor Yukio Yoo 1-280 Higashi Koikekubo, Kokubunji City, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Tomio Yamamoto 1-280 Higashi Koikebo, Kokubunji City, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Akira Ozaki 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd.Central Research Laboratories (72) Inventor Kazuki Tanahashi 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Person Jun Fumioka Kozuhara, Odawara City, Kanagawa Prefecture 2880 Address Hitachi Storage Systems Division, Hitachi, Ltd. (72) Inventor Yoshiki Kato 2880 Kozu, Odawara-shi, Kanagawa Prefecture Inside Storage Systems Division, Hitachi, Ltd. (72) Inventor Masaki Ohura 2880, Kofutsu, Odawara-shi, Kanagawa Prefecture Stock Association Hitachi, Ltd. Storage Systems Division

Claims (7)

[Claims] 1. A magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed directly on the non-magnetic disk substrate or via an under film, wherein Cr, The base film made of Mo, W, Nb, Ta or an alloy containing these as main components has a thickness of 5
A method for manufacturing a magnetic recording medium, wherein the magnetic recording medium is formed to have a thickness of 500 nm to 500 nm. 2. A surface of a magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed directly on the non-magnetic disk substrate or via a base film, measured in a direction perpendicular to a circumferential direction of the recording medium. A method for manufacturing a magnetic recording medium, wherein a center line average roughness Ra (r) is in a range of 0.3 nm or more and 3 nm or less. 3. A magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed directly or via an underlayer on the non-magnetic disk substrate, wherein a lower portion between the non-magnetic disk substrate and the magnetic film is provided. On the surface of the ground film, grooves having a depth of 1 nm or more along the circumferential direction of the disk substrate are present at an average of 0.5 or more and 100 or less per 1 μm in a direction perpendicular to the circumferential direction. Of manufacturing a magnetic recording medium. 4. A surface measured in a direction perpendicular to a circumferential direction of a magnetic recording medium in a magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed on the non-magnetic disk substrate directly or via an underlayer. When the ratio of the center line average roughness Ra (r) to the surface center line average roughness Ra (θ) measured in the circumferential direction, Ra (r) / Ra (θ) is 1.1 or more and 3.0 or less. A method for manufacturing a magnetic recording medium, comprising: 5. A magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed on the non-magnetic disk substrate directly or via an underlayer by applying a magnetic field in a circumferential direction of the magnetic recording medium. Coercive force Hc (θ) and the coercive force H measured by applying a magnetic field in a direction substantially perpendicular to the circumferential direction.
c (r), the coercive force orientation ratio ΔHc (θ) −
Hc (r)｝ / {Hc (θ) + Hc (r)} is 0.1 or more, 0.1
7. A method for manufacturing a magnetic recording medium, wherein the number is 7 or less. 6. In a magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed directly on the non-magnetic disk substrate or via an underlayer, a magnetic field is applied to the surface of the substrate and a sample is formed in the surface of the substrate. The method for producing a magnetic recording medium, wherein the magnetic anisotropy energy measured by rotating is not less than 3 × 10 ⁴ J / m ^{3 and not} more than 5 × 10 ⁵ J / m ³ . 7. In a magnetic recording medium having a non-magnetic disk substrate and a magnetic film formed directly on the surface of the non-magnetic disk substrate or via an underlayer, measurement is performed in a direction perpendicular to the circumferential direction of the magnetic recording medium. Surface center line average roughness R
7. The method for manufacturing a magnetic recording medium according to claim 2, wherein the range of a (r) is 0.3 nm or more and 3 nm or less.