JP2000298823A - Magnetic storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent destruction of recorded information due to contact of slider of magnetic head with a medium by lowering the surface height of unit recording portion than the surface height of non-recording portion. SOLUTION: A magnetic disc medium 10 includes, on a disc type substrate 12, a number of small unit recording portions 14 arranged concentrically or spirally in the circumference direction and radius direction with an interval and non-recording portion 16 filling the areas between adjacent fine unit recording portions 14. Each small unit recording portion 14 is electrically independent to prevent crosstalk in the adjacent small unit recording portions 14, sets the surface height lower than the surface height of the non-recording portion 16 and recesses the small unit recording portions 14 from the surface of the non- recording portion 16. Accordingly, even if a slider comes in contact with the medium surface, information recorded in the small unit recording portion 14 is not destroyed and adsorption of slider to the whole surface of medium can be prevented because fine roughness exists on the surface of medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic recording medium, and more particularly to, for example, a magnetic disk drive (HD).
The present invention relates to a magnetic recording medium used in a magnetic recording / reproducing apparatus such as a hard disk drive (D), and more particularly to a structure of a magnetic recording medium having a high recording density.

[0002]

2. Description of the Related Art Large-capacity storage devices, especially hard disk drive devices, have been significantly increased in capacity and density in terms of high data transfer speed, high-speed access, high reliability, and low price. Improvement in areal recording density is achieved by miniaturization of recording magnetic domains formed in the magnetic recording layer, which currently exceeds 5 gigabits per square inch to 10 gigabits to 1 gigabits.
The development aiming at 00 gigabit is in progress.

[0003] As a magnetic head for performing recording and reproduction, a composite magnetic head in which an inductive head is used as a recording head and a magnetoresistive head (MR head) is used as a reproducing head is used. Since the output of the MR head is determined by a change in magnetic flux per unit length in the circumferential direction, the output does not decrease in principle even if the track width is reduced. Therefore, by using an MR head, it is possible to reduce the track width. The same can be said for a giant magnetoresistive head (GMR head) where a higher recording density can be expected.

[0004] However, if the track width is too narrow, interference (crosstalk) due to magnetic signals of adjacent recording tracks increases, which causes a problem of deterioration of reproduction signals.

Although the areal recording density can be improved by shortening the recording bit length, if the recording bit length is too short, the interference (partial erasure) of the magnetic signal between adjacent bits increases, and the reproduction signal Deterioration becomes a problem.

In Japanese Patent Application Laid-Open No. 9-297918, a plurality of recording sections each including a rectangular area having a track width and a specified minimum bit length of two sides are provided, and the plurality of recording sections are separated from each other by a gap. A magnetic recording medium which is arranged in such a manner as to store information in a recording unit is described. This medium is a so-called patterned medium. In the case of a patterned medium, it is possible to reduce deterioration of a reproduced signal due to crosstalk and partial erasure.

[0007]

By the way, in order to achieve a high recording density, it is essential to reduce the flying height of a slider on which a magnetic head is mounted. However, when the flying height of the slider is reduced, the frequency at which the slider contacts the magnetic recording medium due to disturbance increases. When the slider comes into contact, the magnetic recording layer may be damaged and the recorded information may be destroyed. However, in a patterned medium, an effective means to avoid destruction of recorded information caused by contact between the slider and the medium is as follows.
Not previously proposed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a so-called patterned medium having a recording track in which unitary recording sections made of a magnetic material are arranged with a non-recording section made of a non-magnetic material interposed therebetween. An object of the present invention is to prevent destruction of recorded information caused by contact with a medium.

[0009]

This and other objects are achieved by the present invention which is defined below as (1) to (4). (1) There is a recording track in which unit recording units made of a magnetic material are arranged with a non-recording unit made of a non-magnetic material interposed therebetween, and the surface height of the unit recording unit is higher than the surface height of the non-recording unit. Even low magnetic recording media. (2) The magnetic recording medium according to (1), wherein the surface height of the unit minute recording portion is 5 to 30 nm lower than the surface height of the non-recording portion. (3) The magnetic recording medium according to (1) or (2), wherein each unit minute recording portion is a single magnetic domain. (4) Co, Co-Cr, Co-C in the unit minute recording portion
The magnetic recording medium according to any one of the above (1) to (3), which is composed of any one of r-Ta and Co-Cr-Pt.

[0010]

In the magnetic recording medium of the present invention, as described above, the surface height of the unit minute recording portion is set lower than the surface height of the non-recording portion. Therefore, even if the slider contacts the surface of the medium during the magnetic recording / reproducing operation, it does not contact the unit minute recording portion. Therefore, even if the flying height of the slider is reduced to improve the recording density, the recorded information is not destroyed.

Conventionally, in order to prevent the slider from being attracted to the medium surface, irregularities are formed on the substrate surface and a magnetic recording layer is formed thereon to form irregularities on the medium surface. . On the other hand, in the medium of the present invention, since irregularities are formed by the unit minute recording portion and the non-recording portion having different surface heights, it is not necessary to provide a special structure for preventing adsorption.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is mainly applied to a magnetic disk medium. FIG. 1 is a perspective view showing a configuration example of the magnetic disk medium of the present invention.

A magnetic disk medium 10 shown in FIG. 1 has a large number of unit minute recording portions 14 arranged concentrically or spirally on a disk-shaped substrate 12 at intervals in a circumferential direction and a radial direction. Adjacent unit micro-recording unit 1
And a non-recording portion 16 that fills the space between the four. The unit minute recording unit 14 is made of a magnetic material that magnetically records information,
The non-recording section 16 is made of a non-magnetic material. Since each unit minute recording unit 14 is almost completely magnetically isolated, crosstalk and partial erasure between adjacent unit minute recording units can be prevented.

In the present invention, the surface height of the unit minute recording portion 14 is set lower than the surface height of the non-recording portion 16. That is, the surface of the unit minute recording section 14 is
It is concave with respect to the surface. Therefore, in the medium of the present invention, even if the slider comes into contact with the medium surface, the information recorded in the unit minute recording section 14 is not destroyed. Further, in the medium of the present invention, since fine irregularities exist on the medium surface, it is possible to prevent the slider from being attracted to the medium surface.

The amount of depression of the surface of the unit minute recording portion 14 with respect to the surface of the non-recording portion 16, that is, the difference between the surface heights of the two is small.
Preferably it is 5 to 30 nm, more preferably 5 to 20 nm. If the dent amount is too small, the effect of the present invention will be insufficient, and if the dent amount is too large, it will be difficult to obtain a sufficient reproduction output.

Each unit minute recording section 14 preferably has a single magnetic domain structure. With a single magnetic domain structure, the crystal grain size constituting the unit minute recording portion can be increased,
Deterioration of magnetization due to thermal disturbance can be suppressed. Also,
With a single domain structure, the switching speed of magnetization can be increased.

The shape of the unit minute recording portion 14 is not particularly limited, but is preferably a shape having a major axis and a minor axis. Specifically, in addition to the rectangular parallelepiped shape as shown in FIG. 1, for example, a shape obtained by cutting a spheroid into approximately half may be used. In order to increase the bit density and obtain a sufficient output, the unit minute recording unit 14 has a shape having a major axis and a minor axis, and the major axis is parallel to the track width direction (disc radial direction). It is preferable that the short axis is arranged in parallel with the track length direction (disc circumferential direction).

Although the size of the unit minute recording portion 14 is not particularly limited, the length of the major axis is usually 0.1 to 1.0 μm, the length of the minor axis is 0.05 to 0.5 μm, and the thickness is 10 μm. ~ 100nm
It is preferable to set the degree.

The magnetic material constituting the unit minute recording portion 14 is not particularly limited, but is preferably Co, Ni, Fe or an alloy containing at least one of these.
In particular, Co, Co-Cr, Co-Cr-Ta or Co
-Cr-Ti is preferred. Note that the present invention is applicable to both in-plane magnetization media and perpendicular magnetization media.

In the magnetic recording medium of the present invention, as shown in FIGS. 3 and 4, between the substrate 12 and the unit micro-recording unit 14, the base layer 1 for controlling the orientation is in contact with the unit micro-recording unit 14.
8 may be formed. The composition of the underlayer 18 may be appropriately determined according to the constituent material of the unit minute recording portion 14 so that a desired orientation is obtained. For example, the unit minute recording unit 1
4 is made of the above-described Co—Cr-based magnetic material, and
When using an in-plane magnetization medium, the underlayer 18 is made of Ti, Ru, G
It is preferable to be composed of any one of e, Zr and Cr. When the present invention is applied to a perpendicular magnetization medium, a soft magnetic underlayer is usually provided between the substrate 12 and the unit minute recording section 14.

In order to protect the surface of the medium from contact with the magnetic head, a protective layer or a lubricating layer may be provided on the surface as in the case of the conventional medium. The protective layer may be made of, for example, C or SiO _2, and may be formed by a sputtering method or the like. The lubricating layer may be composed of a known lubricant, and may be formed by a spin coating method or the like.

The non-magnetic material constituting the non-recording portion 16 includes oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , and Si.
₃ N _4, AlN, nitride such as TiN, carbide TiC or the like,
A boride such as BN and a polymer compound of any of C type, CH type and CF type are used.

The substrate 12 may be made of a usual magnetic disk substrate material such as aluminum alloy, glass, silicon and the like. Usually, the thickness of the substrate 12 may be about 500 to 1000 μm.

Next, an example of a method for manufacturing the magnetic recording medium of the present invention will be described with reference to FIG.

In this method, first, as shown in FIG. 5A, a photoresist layer 100 is formed on the substrate 12 by coating.

Next, the photoresist layer 100 is patterned by photolithography to obtain a shape shown in FIG. In the concave portion formed by this patterning, the photoresist is completely removed, and the surface of the substrate 12 is exposed. The non-recording portion 16 is finally contained in this concave portion.
Is formed. In the above photolithography,
For example, exposure using a mask, exposure using a laser beam whose irradiation position can be controlled, or exposure using an electron beam device can be used.

Next, as shown in FIG. 5C, a non-magnetic substance 106 is deposited on the photoresist layer 100 and the exposed surface of the substrate 12 by sputtering or the like.
At this time, as shown in the figure, it is preferable that the thickness of the nonmagnetic substance 106 attached is smaller than the thickness of the photoresist layer 100. Thereby, removal of the photoresist layer 100 becomes easy.

Next, by removing the photoresist layer 100 with a resist removing liquid, the non-magnetic substance 106 adhered thereon is also removed at the same time. As a result, as shown in FIG. 5D, only the non-magnetic substance 106 attached to the surface of the substrate 12 remains. Note that acetone, MEK, or the like can be used as the resist removing liquid, for example.

Next, on the non-magnetic substance 106 and the substrate 12
The magnetic substance 104 is adhered to the exposed surface of the substrate by sputtering or the like to obtain a state shown in FIG. Subsequently, the magnetic substance 104 attached on the non-magnetic substance 106
Is removed by chemical mechanical polishing. As a result, FIG.
As shown in (f), the magnetic disk medium 10 in which the surface height of the unit minute recording portion 14 is lower than the surface height of the non-recording portion 16
Is obtained. Note that the magnetic substance 104 in FIG.
Is set so that the difference between the surface height of the unit minute recording portion 14 and the surface height of the non-recording portion 16 becomes a desired value after the completion of the chemical mechanical polishing.

Next, another example of the method for manufacturing the magnetic recording medium of the present invention will be described with reference to FIG.

In this method, first, as shown in FIG. 6A, a non-magnetic substance 106 is deposited on the substrate 12 by sputtering or the like, and then a photoresist layer 100 is formed thereon by coating.

Next, the photoresist layer 100 is patterned by photolithography to obtain a shape shown in FIG. In the concave portion formed by this patterning, the photoresist is completely removed, and the nonmagnetic material 10 is removed.
6 Surfaces are exposed.

Next, using the photoresist layer 100 as an etching mask, the nonmagnetic substance 106 is etched by RIE (Reactive Ion Etching) or the like. At this time, as shown in FIG. 6C, the etching of the nonmagnetic substance 106 may be limited to only a part in the height direction.
Etching may be performed until the surface is exposed.

Next, the magnetic substance 104 is deposited on the exposed surface of the non-magnetic substance 106 and on the photoresist layer 100 by sputtering or the like to obtain a state shown in FIG. Subsequently, by removing the photoresist layer 100 with a resist removing liquid, the magnetic substance 104 attached thereon is also removed at the same time. As a result, FIG.
As shown in (e), the magnetic disk medium 10 in which the surface height of the unit minute recording portion 14 is lower than the surface height of the non-recording portion 16
Is obtained. Note that the magnetic substance 104 in FIG.
Is set so that the difference between the surface height of the unit minute recording portion 14 and the surface height of the non-recording portion 16 becomes a desired value.

[0035]

[Example] 1.235 mm length, 1.0 mm width, 0.3 mm height
A composite magnetic head was prepared by mounting a recording head and a reproducing head on a 30% slider (weight 1.5 mg) made of Altic (Al ₂ O ₃ .TiC). The recording head has
An inductive head having a magnetic pole width of 0.1 μm and a gap length of 0.2 μm was used, and an MR head was used as a reproducing head.

The magnetic disk medium was manufactured by the method shown in FIG. The unit minute recording portion 14 is a rectangular parallelepiped, and its size is 0.2 in the recording track width direction.
μm, 0.1 μm in the recording track length direction, thickness 2
It was set to 0 nm. The interval between the adjacent unit minute recording portions 14 (dimension of the non-recording portion 16) is 0.16 μm in the recording track width direction and 0.06 μm in the recording track length direction.
8 μm, and the thickness of the non-recording portion 16 was 40 nm. Therefore, the unit minute recording portion 14 with respect to the surface of the non-recording portion 16
The amount of depression on the surface is 20 nm. The track pitch is 0.36 μm (70 kTPI) and the bit pitch is 0.18
μm (141 kBPI). This recording density is 10 Gb / in ²
Is equivalent to

The unit minute recording section 14 is a single magnetic domain structure made of Co and has a coercive force (Hc) of 750 Oe.
The axis of easy magnetization was oriented in the recording track length direction. The non-recording portion 16 was made of carbon.

Recording was performed on this magnetic disk medium using the above-described composite magnetic head. The rotation speed of the magnetic disk medium is 10,000 rpm, and the flying height of the slider is 2
It was 5 nm. After recording, the magnetization state of the magnetic disk medium is changed to M
Observation with an FM (magnetic force microscope) confirmed that the unit minute recording portion was magnetized according to the recording signal.

Next, CSS (contact start and stop) was repeated 50,000 times using the medium rotation speed and the magnetic head flying height as the above values. As a result, no destruction of recorded information due to adsorption of the slider to the magnetic disk medium was observed.

On the other hand, the unit minute recording unit 14 and the non-recording unit 16
Each of the comparative media was prepared in the same manner as the above-mentioned magnetic disk media, except that both were set to a thickness of 20 nm and the surface heights of both were the same. In this comparison medium,
In order to prevent the slider from being attracted to the surface, a conventional texture treatment was applied to the substrate surface.

When recording was performed on this comparative medium under the above conditions, recording was possible in the same manner as the medium of the present invention. However, when the CSS test was performed, part of the recorded information became unreproducible at 12,000 times. At this time, the CSS test was stopped and the medium surface was observed by MFM. As a result, destruction of recorded information was observed in many unit minute recording portions.

The effects of the present invention are clear from the above examples.

[Brief description of the drawings]

FIG. 1 is a partially enlarged perspective view showing a configuration example of a magnetic recording medium of the present invention.

FIG. 2 is a sectional view of the magnetic recording medium taken along line AA of FIG. 1;

FIG. 3 is a partially enlarged perspective view of a configuration example of a magnetic recording medium of the present invention.

FIG. 4 is a sectional view of the magnetic recording medium taken along line BB of FIG. 3;

FIG. 5 is a sectional view illustrating an example of a method for manufacturing a magnetic recording medium according to the present invention.

FIG. 6 is a cross-sectional view illustrating an example of a method for manufacturing a magnetic recording medium according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic disk medium 12 Substrate 14 Unit minute recording part 16 Non-recording part 18 Underlayer 100 Photoresist layer 104 Magnetic substance 106 Nonmagnetic substance

Claims (4)

[Claims] 1. A recording track in which unitary minute recording portions made of a magnetic material are arranged with a non-recording portion made of a nonmagnetic material interposed therebetween, wherein the surface height of the unitary minute recording portion is the surface of the non-recording portion. A magnetic recording medium that is lower than its height. 2. The magnetic recording medium according to claim 1, wherein the surface height of the unit minute recording portion is lower by 5 to 30 nm than the surface height of the non-recording portion. 3. The magnetic recording medium according to claim 1, wherein each unit minute recording portion is a single magnetic domain. 4. The unit minute recording portion is made of Co, Co-Cr, C
4. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is made of one of o-Cr-Ta and Co-Cr-Pt.