JPH09330515A - Magnetic recording medium and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a magnetic recording medium, which can form arbitrarily controlled irregularities accurately and economically. SOLUTION: When the manufacture of a recording medium having at least a nonmagnetic substrate 12, a magnetic layer and a lubricant layer is performed by this method, pulse layer is selectively applied on the region including the part, where a magnetic head is brought into contact with the recording medium through the mask having the opening part in a specified shape at the time of the starting and stopping of the recording medium. Then, the surface is made rouph, and many irregularity parts 22 are formed.

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 and a method for manufacturing the same, and more particularly to a magnetic recording medium in which a substrate surface has irregularities of a predetermined shape formed by laser texture and a method for manufacturing the same. .

[0002]

2. Description of the Related Art In a magnetic disk such as a fixed disk used as an external storage device of a computer or the like, a magnetic head is used as one of means for improving its electromagnetic conversion characteristics. A method of reducing the distance between the disk and the magnetic disk, that is, the glide height is used. Therefore, it can generally be said that the surface of the magnetic disk is preferably smooth, but if it is too smooth, the magnetic head sticks to the magnetic disk,
A so-called head suction phenomenon occurs, and the magnetic disk and the magnetic head may be damaged. Therefore, a texture process for making the surface of the magnetic disk an appropriate roughness is generally performed.

As such texture processing, for example,
As described in JP-A-3-272018 and JP-A-6-290452, a method of mechanically polishing the surface of a magnetic disk substrate with a polishing tape or the like,
A method is known in which a surface of a substrate of a magnetic disk is irradiated with a pulse laser to form discrete uneven portions to roughen the surface.

However, in the method of mechanically polishing with the above-mentioned polishing tape or the like, when the substrate is a brittle material,
Micro cracks easily enter the substrate surface during polishing,
As a result, errors easily occur in the obtained magnetic recording medium. It is also difficult to form zone texture. on the other hand,
JP-A-3-272018 and JP-A-6-29045
In the method described in Japanese Patent Publication No. 2, the surface of the substrate is roughened by a single beam laser, so that the productivity is not good. Further, the shape of the uneven portion formed is limited to a circle or an ellipse, and it is difficult to form the uneven portion optimized for improving the wear resistance of the magnetic recording medium.

Accordingly, an object of the present invention is to provide a method of manufacturing a magnetic recording medium capable of forming arbitrarily controlled irregularities accurately and economically. Another object of the present invention is to provide a magnetic recording medium having high durability and abrasion resistance and excellent error characteristics.

[0006]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to achieve the above object, it is possible to selectively irradiate a substrate with a pulse laser through a mask material having an opening of a predetermined shape. As a result, it was found that an uneven portion having a predetermined shape substantially corresponding to the shape of the opening of the mask material is formed on the substrate surface.

The present invention has been made based on the above findings, and in a method for manufacturing a magnetic recording medium having at least a non-magnetic substrate, a magnetic layer and a lubricant layer, the magnetic recording on the non-magnetic substrate is performed. A region including a portion where the magnetic head comes into contact with the magnetic recording medium at the time of starting and stopping the medium is selectively irradiated with a pulse laser through a mask material having an opening of a predetermined shape to roughen the surface. The above object is achieved by providing a method for manufacturing a magnetic recording medium, which is characterized by forming a large number of concavo-convex portions by planarizing.

The present invention also provides, as a preferred magnetic recording medium manufactured by the above method, a magnetic recording medium having at least a non-magnetic substrate, a magnetic layer and a lubricating layer, wherein the magnetic recording is performed on the non-magnetic substrate. A large number of uneven portions are formed in a region including a portion where the magnetic head and the magnetic recording medium come into contact with each other when the medium is started and stopped,
The concavo-convex portion has a concave portion whose lowermost portion is lower than the center line (JIS B0601) in a region where the concavo-convex portion is not formed, and a position which surrounds the concave portion and whose highest portion is higher than the central line. And the convex contour portion in FIG.
The present invention provides a magnetic recording medium having a size of 0 μm ² and a total area of 50 to 99.8% of the area of the region where the irregularities are formed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION First, a preferred embodiment of a method for manufacturing a magnetic recording medium of the present invention will be described with reference to the drawings. Here, FIG. 1 is a schematic view showing an apparatus used in an embodiment of a method for manufacturing a magnetic recording medium of the present invention,
2A to 2C are enlarged plan views showing the shape of the main part of the mask material used in the method of the present embodiment.

In the method of the present embodiment, as shown in FIG. 1, a region (hereinafter referred to as a region) on the non-magnetic substrate 12 including a portion where the magnetic head and the magnetic recording medium come into contact with each other when the magnetic recording medium is started and stopped. This region is referred to as a "head landing zone"), and a pulse laser 32 is selectively irradiated through a mask material 30 having an opening of a predetermined shape to roughen the surface to form a large number of irregularities. Form.

The method of this embodiment will be described in more detail. The pulse laser 3 generated by the laser device 34 is used.
2 passes through the mask material 30 to become a multiple beam. The multi-beam pulse laser 32 is condensed by a lens 36 to have a predetermined beam diameter, and then is irradiated onto the head landing zone of the non-magnetic substrate 12. The non-magnetic substrate 12 is held by one end of a spindle 38 at the center thereof. The other end of the spindle 38 is connected to a rotating means (not shown) so that the non-magnetic substrate 12 can rotate in the circumferential direction at a predetermined rotation speed. As a result, only the head landing zone is irradiated with the pulse laser 32, and only the head landing zone can be selectively roughened to form a large number of uneven portions.

The method of forming the uneven portion on the surface of the non-magnetic substrate 12 will be described in more detail.
Material removal by the energy of the pulse laser 32
It is formed by deformation. That is, a photochemical reaction occurs in the portion irradiated with the pulse laser 32, the bonds between the atoms and molecules in the portion are cut off, and the atoms and molecules are instantaneously dispersed and scattered to form the uneven portion. . As a result, the surface of the non-magnetic substrate 12 can be roughened without generating microcracks.

As the mask material 30 having an opening used in the method of the present embodiment, for example, a mask material in which cross-shaped slits shown in FIG.
A mask material formed with slits (slits formed by three straight lines having the same length at 120 degrees apart from each other and one end located on the same point) shown in FIG.
A mesh mask material as shown in (c) can be used, but is not limited thereto. Then, by using these mask materials, an uneven portion substantially corresponding to the shape of the opening of the mask material is formed on the surface of the non-magnetic substrate.
For example, when the mask material shown in FIG. 2A is used among the mask materials 30 shown in FIG. 2, an uneven portion having a shape shown in FIG. 4 (described later) is formed, and the mask material shown in FIG. When the mask material shown in the figure is used, an uneven portion having a shape shown in FIG. 5 (described later) is formed. Further, when the mask material shown in FIG. 2C is used, a substantially circular or elliptical uneven portion is formed.

The mask material 30 shown in FIGS. 2A and 2B.
Width, size and number of slits in Fig. 2 (c)
There is no particular limitation on the wire diameter, line spacing, etc. in the mask material 30 shown in (4), and it can be appropriately selected depending on the size of the uneven portion to be formed on the surface of the non-magnetic substrate, the degree of overlapping, and the like. The slits in the mask material 30 shown in FIGS. 2A and 2B can be formed by etching a plate-shaped material such as stainless steel using a photoresist. For example, when using the mask material 30 shown in FIG. 2A, the vertical and horizontal lengths of the cross-shaped slits are preferably 0.001 to 100 μm, and more preferably 0.01 to 20 μm. preferable. The width of the slit is preferably 0.001 to 100 μm, more preferably 0.01 to 20 μm.

The laser device used in the method of the present embodiment can be appropriately selected according to the material of the non-magnetic substrate for forming the concavo-convex portion, for example, when a carbon substrate is used as the non-magnetic substrate. For, an excimer laser can be preferably used. Further, the period, output, irradiation number, and the like of the pulse laser in the laser device can be appropriately selected according to the type of the nonmagnetic substrate and the degree of roughening. For example, when the carbon substrate is irradiated with an excimer laser, the pulse cycle is 50
To 200 kHz, and the output (energy) is preferably 0.01 to 1000 mJ.
The irradiation number is preferably 1000 to 1000 × 10 ³ times, and the substrate rotation number is preferably 1 to 100,000 rpm.

In the method of this embodiment, the non-magnetic substrate is irradiated with the pulse laser at a right angle, but the method of the present invention is not limited to this embodiment. For example, the pulse laser may be obliquely irradiated. Good. Further, as the mask material used in the method of the present invention, not only a mask material having only one kind of slit formed but also a mask material having two or more kinds of slits formed may be used. Alternatively,
Two or more mask materials may be used in combination. It should be noted that, for points that are not particularly described in detail regarding the method of the present invention, the description regarding the method for manufacturing a normal magnetic recording medium is appropriately applied.

Next, a preferred embodiment of a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium of the present invention will be described with reference to the drawings. Here, FIG. 3 is a schematic cross-sectional view showing the structure of a preferred embodiment of the magnetic recording medium of the present invention.

The magnetic recording medium 10 of the embodiment shown in FIG.
Includes a non-magnetic substrate 12, and first and second underlayers 13 and 14, a magnetic layer 16, a protective layer 18, and a lubricant layer 20, which are sequentially provided on the non-magnetic substrate 12. In addition,
In the magnetic recording medium 10 of the embodiment shown in FIG. 3, the uneven portion is omitted for simplicity.

Each layer constituting the magnetic recording medium 10 of the present embodiment will be described. First, as the non-magnetic substrate 12, for example, an Al substrate, a NiP plated Al alloy substrate, a strengthened glass substrate, a crystallized glass substrate, a ceramics. A substrate, a Si alloy substrate, a Ti substrate, a Ti alloy substrate, a plastic substrate, a carbon substrate, a substrate made of a composite material of these, or the like can be used. Of these, the carbon substrate, especially the glassy carbon substrate, is advantageous in reducing the diameter / thin plate, is excellent in impact resistance and heat resistance, and is also electrically conductive, so that it is preferably used in the present invention. .

According to the method of the present invention, a region of the non-magnetic substrate 12 including a portion where the magnetic head and the magnetic recording medium come into contact with each other at the time of starting and stopping the magnetic recording medium, that is, the head landing zone is predetermined according to the method of the present invention. By selectively irradiating the pulse laser through the mask material having the opening of the shape, the surface is roughened, and a large number of irregularities are formed.

The shape of the uneven portion will be described with reference to FIG. Here, FIG. 4 is a schematic perspective view showing the shape of the uneven portion. The uneven portion 22 shown in FIG. 4 has a predetermined center line average roughness R by the single pulse of the pulse laser.
It is formed as a single concavo-convex portion on the mirror-finished non-magnetic substrate 12 having a, and its contour is substantially clover-shaped. The concavo-convex portion 22 includes a concave portion 28 and the concave portion 2
And a convex contour portion 24 that surrounds 8 and defines the outer shape of the irregular portion 22. The convex contour portion 24 is
The non-magnetic substrate 12 is raised in a convex shape from the flat portion 26, and its highest portion (ridge line portion) is located higher than the center line of the flat portion 26 (measured in accordance with JIS B 0601). . On the other hand, the concave portion 28 surrounded by the convex contour portion 24 has the non-magnetic substrate 1
The second flat portion 26 is recessed in a concave shape, and the lowest portion thereof is located at a position lower than the center line. Further, in the concave-convex portion 22 shown in FIG. 4, it is also preferable that a protrusion (not shown) protruding in a convex shape is formed at a substantially central portion of the concave portion 28.

The height of the convex contour portion 24 is preferably 10 to 500 Å, more preferably 20 to 200 Å, based on the center line. If the height is less than 10 Å or exceeds 500 Å, the flying posture of the magnetic head fluctuates greatly. On the other hand, the depth of the recess 28 is preferably 10 to 3000 Å, and more preferably 20 to 500 Å, based on the center line.
If the depth is less than 10Å, the centerline average roughness Ra of the uneven portion is the centerline average roughness Ra of the non-magnetic substrate 12.
Therefore, the effect of reducing the contact area with the magnetic head is small, and if it exceeds 3000 Å, the floating stability of the magnetic head may be affected.

The above-mentioned concavo-convex portion 22 has an average area of 0.1 to 500 μm ² , and 0.2 to 100 μm.
m ² is preferred. The average area is 0.1 μm
^If it is less than ² , it is difficult to control the shape of the uneven portion 22, and if it exceeds 500 μm ² , the flying posture of the magnetic head is disturbed and the risk of head crash increases. Further, the area of the uneven portion 22 is at least 0.05 μm ² or more,
The maximum is preferably 900 μm ² or less,
In particular, the minimum is 0.1 μm ² or more, and the maximum is 5
It is preferably 00 μm ² or less. The total area of the uneven portion 22 is 50 to 99.8% and 70 to 98% of the area of the region (that is, the head landing zone) in which the uneven portion 22 is formed. Is preferred. If the total area of the uneven portion 22 is less than 50% of the area of the head landing zone, the effect of reducing the frictional force between the magnetic head and the magnetic recording medium at the time of starting and stopping the magnetic recording medium is small, which is 99.8%. When it exceeds, the contact pressure between the magnetic head and the magnetic recording medium in the convex contour portion 24 becomes large, and the head crash easily occurs. The area of the uneven portion 22 can be measured by SEM (scanning electron microscope), ZYGO (laser light three-dimensional surface structure analysis microscope), or atomic force microscope (AFM) observation.

In the concave-convex portion 22, the projected area ratio between the convex-shaped contour portion 24 and the concave-convex portion 22 [convex-shaped contour portion / (convex-shaped contour portion + recessed portion)] is 2 to 50%. It is preferably 5 to 30%, more preferably 5 to 30%. If the projected area ratio is less than 2%, the sliding durability becomes poor, and if it exceeds 50%, the magnetic head is likely to be attracted, so that it is preferably within the above range. The method of measuring the projected area ratio will be described in detail in Examples described later.

Another shape of the uneven portion 22 will be described with reference to FIG. Here, FIG. 5 is a schematic perspective view (corresponding to FIG. 4) showing another shape of the uneven portion. It should be noted that, for points that are not described in detail in FIG. 5, the description described in detail with reference to FIG. 4 is appropriately applied. Further, in FIG. 5, the same parts as those in FIG. 4 are designated by the same reference numerals. Uneven portion 22 shown in FIG.
Has a substantially triangular outline. Then, the uneven portion 22
Is similar to the uneven portion shown in FIG.
Is raised in a convex shape from the flat portion 26 of the non-magnetic substrate 12, and the recess 28 surrounded by the convex-shaped contour portion 24 is recessed from the flat portion 26 of the non-magnetic substrate 12 in a concave shape. .

In the magnetic recording medium of the present invention, the shape of the uneven portion may be a shape other than the above-mentioned shape, for example, a circular shape or an elliptical shape. From the viewpoint of the desired strength, it is preferable to form the substantially clover-shaped and substantially triangular uneven portions as shown in FIGS. 4 and 5, respectively.

In the magnetic recording medium of the present invention,
It is preferable that the concavo-convex portions 22 as shown in FIG. 4 and FIG. That is, it is preferable that the pulse laser is irradiated as a multiple beam to form a plurality of concavo-convex portions 22, 22, ... As shown in FIG. By forming the uneven portion having such a shape, the contact area with the magnetic head can be reduced, the interval between the convex contour portions can be controlled, and the degree of freedom in texture formation is increased, which is preferable. Further, in the magnetic recording medium of the present invention, a plurality of uneven portions having different shapes may be formed on one substrate. It should be noted that in order to form a shape in which a plurality of concavo-convex portions are overlapped as shown in FIG. 6, an interval between slits in the mask material shown in FIGS. 2A and 2B, and FIG. 2C are shown. It suffices to reduce the distance between the meshes in the mask material.

The head landing zone of the non-magnetic substrate, on which the irregularities are formed, has a center line average roughness (Ra) of 10 to 100 liters from the viewpoint of improving the durability and wear resistance of the magnetic recording medium. It is preferable that the center line average height (Rp) is 20 to 300 Å.

In the magnetic recording medium 10 of the embodiment shown in FIG. 1, the first underlayer 13 provided on the non-magnetic substrate 12 is used for the purpose of further reducing medium noise, and Ti or It is preferably composed of a Ti alloy. On the other hand, the second underlayer 14 provided on the first underlayer 13 is provided for the purpose of improving the magnetostatic characteristics of the magnetic layer 16.
For this purpose, it is preferable to use a material having a lattice constant close to that of the substance forming the magnetic layer 16. In particular, the second underlayer 14 is preferably made of Cr or a binary alloy containing Cr from the viewpoints of improving magnetostatic characteristics and reducing medium noise. Examples of the binary alloy containing Cr include CrTi, CrMo, CrW, CrNb,
Examples thereof include CrSi, CrCo, CrTa, and the like.
The thicknesses of the first underlayer 13 and the second underlayer 14 are preferably 5 to 200 nm and 5 to 150 nm, respectively.

Next, the magnetic layer 16 provided on the second underlayer 14 will be described. As the magnetic layer 16, for example, a metal thin film type formed by PVD (Physical Vapor Deposition) is used. A magnetic layer can be mentioned. As a material for forming the metal thin film type magnetic layer, for example, Co
Cr, CoNi, CoCrX (excluding X = Cr), CoCrPtX (excluding X = Cr and Pt), CoSm, CoSmX (excluding X = Sm), CoNiX (excluding X = Ni) ) And CoW
X (however, X = W is excluded) (where X is Ta, P
t, Au, Ti, V, Cr, Ni, W, La, Ce, P
r, Nd, Pm, Sm, Eu, Li, Si, B, Ca,
As, Y, Zr, Nb, Mo, Ru, Rh, Ag, Sb
And a Co-based magnetic alloy containing Co as a main component represented by (indicating one or more metals selected from the group consisting of Hf and the like) and the like. In use, these can be used individually or in combination of 2 or more types. The magnetic layer 16 has a thickness of 20 to 50 n.
It is preferably m, but not limited to this range.

The protective layer 18 provided on the magnetic layer 16 is used to protect the magnetic layer 16. The protective layer is preferably formed of a material having high mechanical strength from the viewpoint of wear resistance, and for example, Al, Si, Ti, Cr, Zr, Nb, Mo, T.
oxides of metals such as a and W (silicon oxide, zirconium oxide, etc.); nitrides of the metal (boron nitride, etc.); carbides of the metal (silicon carbide, tungsten carbide, etc.); carbon such as diamond-like carbon (carbon ) And boron nitride are preferably used. Among the above materials, carbon, silicon carbide, tungsten carbide, silicon oxide, zirconium oxide, boron nitride or a composite material thereof is preferable, carbon is more preferable, and diamond-like carbon and glassy carbon are particularly preferable. Generally, the thickness of the protective film 18 is preferably 5 to 25 nm. The protective layer 18 can be formed by PVD or the like.

The lubricant layer 18 provided on the protective layer 18 is used to improve the running property and durability of the magnetic recording medium, and has a thickness of 5 to 10, for example.
It is formed by a method of applying a lubricant by spin coating, dip coating, spray coating, or the like so as to be about 0 Å, or a method of vapor phase polymerization (especially photo CVD) of a fluorocarbon compound and oxygen. You can As the lubricant, a fluoropolymer can be preferably used. As the fluorine-based polymer, both those having a polar group in the molecule and those not having a polar group can be used alone or in combination. As the above-mentioned fluoropolymer having a polar group in the molecule, a perfluoropolyether polymer having a molecular weight of 2000 to 4000 and having an aromatic ring or an OH group at a terminal is preferably used. More specifically,-(CF ₂ CF
₂ O) _n- (CF ₂ O) _m -skeleton, an aromatic ring or an OH group at the end, and a molecular weight of 2000 to 4000
Is preferred. Specific examples include Fomblin AM2001 and Fomblin Z-dol (Ausimont). On the other hand, the fluorine-containing polymer having no polar group in the molecule has a molecular weight of 2000 to 10
000 perfluoropolyether polymer,
Those having a perfluoroalkyl group at the terminal are preferably used. More specifically, CF ₃ — (CF ₂ CF
₂ O) _n - is represented by _{(CF 2 O) m -CF 3} , having a molecular weight of 2,000 to 10,000 are preferred. Specific examples include Fomblin Z03 (Ausimont).

In the magnetic recording medium of the present embodiment, since the uneven portion is formed in the head landing zone of the non-magnetic substrate, the uneven portion corresponding to the uneven portion is also formed on the surface of the magnetic recording medium. Is formed. As a result, the magnetic recording medium is excellent in durability and wear resistance.

The magnetic recording medium of the present invention is useful as, for example, a magnetic drum, a magnetic tape, a magnetic card, a magnetic disk, and the like, and is particularly useful as a magnetic disk such as a fixed disk.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to such examples.

Example 1 A magnetic disk having the structure shown in FIG. 3 was manufactured by the following procedure. That is, the density is 1.5 g /
cm ² amorphous carbon substrate (size 2.5 ”)
Was polished to an average surface roughness of 0.5 to 1.0 nm. The surface of this carbon substrate is shown in FIG.
Mask material shown in (c) (wire diameter 0.03 mm, line spacing 0.
08 mm) was used to roughen the surface. A KrF excimer laser (wavelength 248 nm) is used as the laser device 34 in the device shown in FIG. 1, the reduction ratio of the mask material 30 is set to 1/4 by the lens 36, and the irradiation area on the carbon substrate is set to about 2 mm × 4 mm. . Other conditions are shown in Table 1.
According to this, a carbon substrate on which a large number of uneven portions having a substantially circular shape (crater shape) in plan view were formed was obtained. The center line average roughness (Ra) and center line average height (Rp) of this carbon substrate were measured under the following conditions using a stylus type surface roughness meter [manufactured by Tencor Corp .: model P2]. The results are shown in Table 2. Measurement condition : Stylus tip radius: 0.6 μm (needle curvature radius) Stylus pressing pressure: 7 mg Measurement length: 250 μm x 8 points Tracing speed: 2.5 μm / sec Cutoff: 1.25 μm (low pass filter)

The average area (μm ² ) of each of the irregularities and the total area (%) of the irregularities with respect to the area of the head landing zone were measured by the following method. The results are shown in Table 2. SEM (Hitachi, FE-S
EMS-4000), the area where the uneven portion is formed is arbitrarily observed and photographed at three places every 120 degrees, and the maximum value of the area per one of the uneven portion is obtained from the photographic image of each visual field.
The minimum value and the average value were obtained, and the area ratio of the total area of the uneven portion was calculated.

Furthermore, the projected area ratio [the convex contour portion / (the convex contour portion + the concave portion)] of the convex contour portion and the concave and convex portion in the concave and convex portion was measured by the following method. The results are shown in Table 2. A three-dimensional surface structure analysis microscope (manufactured by ZYGO, model MAX2MNT512) is used as a measuring device, and the area 170 μm × 170 μ in which the above-mentioned concavo-convex portion is formed.
m was measured, and the area% at the time of cutting at a depth of 10 Å from the center line (average reference line) in the flat portion where the uneven portion was not formed was obtained and used as the projected area ratio.

After precisely cleaning the carbon substrate, it was loaded on a pallet and set in an in-line type sputtering apparatus having 4 cathodes. Targets of Ti, Cr, CoCr ₁₂ Pt ₆ B ₄ at% and C are installed in the sputtering chamber. The inside of the sputtering chamber is evacuated to a vacuum, and then the above carbon substrate is heated to 200 ° C. by a heater under the condition that Ar gas is introduced into the sputtering chamber at 5 mTorr, and each layer is sequentially formed under the following conditions. I went. (1) First underlayer-Material: Ti-Substrate bias voltage: 0V-Thickness: 50nm (2) Second underlayer-Material: Cr-Substrate bias voltage: 0V-Thickness: 50nm (3) Magnetic layer- _{materials: CoCr 12 Pt 6 B 4 at} % · substrate bias voltage: -100 V, the film thickness: 35 nm (4) protective layer, materials: C-substrate bias voltage: -100 V, thickness: 10 nm

After forming the protective layer, Ar gas was stopped and the carbon substrate was left to stand until the temperature became 50 ° C. or lower. Then, the inside of the sputtering chamber was opened to the atmosphere, and the carbon substrate having the protective layer formed was taken out. Next, tape burnishing was performed on the surface of the protective layer, and then a lubricant Fomblin AM2001 (manufactured by Ausimont) was applied to a thickness of 1.5 nm to obtain a magnetic disk having the configuration shown in FIG. . Each of the obtained magnetic disks was evaluated according to the following [Evaluation criteria for magnetic disks]. The results are shown in Table 2.

[Evaluation Criteria for Magnetic Disks] <CSS Characteristics> Yamaha thin film head (Al ₂ O ₃
TiC slider head) and head load of 3.5
g, head flying height 2.8μ inch, rotation speed 4500rp
The cycle of driving for 5 seconds at m and stopping for 5 seconds was repeated, and the number of times when the coefficient of static friction exceeded 0.6 was 5 to 10
The value of 10,000 times is indicated by A, the value of 1 to 50,000 times is indicated by B, and the value of less than 10,000 times is indicated by C. <GHT characteristics> It was measured with a 50% slider head using MG150T manufactured by PROQUIP. The measurement results are as follows: S with a passing rate of 1.5 μ inch flying height of 90% or more as S, 50 to 90% as A, 30 to 50% as B, and 30% or less as C. displayed. <Error characteristics> Using a 150% slider head and a recording density of 80 KFC using MG150T manufactured by PROQUIP
Evaluation was performed under the conditions of I and a track width of 3.5 μm. The slice level was set to 60%, and for each of the 50 magnetic disks, a missing pulse of continuous 16 bits or less was regarded as one error, and the number of errors was counted and evaluated as follows. A: The number of errors is 0 to 1 in 50% or more of the evaluation disks
There are five. B: 50% or more of the evaluation discs had 16 or more errors
There are 45. C: 50% or more of the evaluation disks have 46 or more errors.

[Examples 2 to 4] A carbon substrate was roughened in the same manner as in Example 1 except that the pulse laser irradiation conditions in Example 1 were changed to those shown in Table 1. Table 2 shows the surface condition of the obtained carbon substrate. After that, the same operation as in Example 1 was performed to obtain a magnetic disk. The magnetic disk thus obtained was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 1 A carbon substrate was prepared in the same manner as in Example 1 except that a polishing tape was used instead of the pulse laser in Example 1 and the surface of the carbon substrate was roughened under the conditions shown in Table 1. Got Table 2 shows the surface condition of the obtained carbon substrate. After that, the same operation as in Example 1 was performed to obtain a magnetic disk. The magnetic disk thus obtained was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2 A carbon substrate was roughened in the same manner as in Example 1 except that the mask material in Example 1 was not used and the conditions shown in Table 1 were used. Table 2 shows the surface condition of the obtained carbon substrate. After that, the same operation as in Example 1 was performed to obtain a magnetic disk. The magnetic disk thus obtained was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0045]

[Table 1]

[0046]

[Table 2]

As is clear from the results shown in Table 2, by selectively irradiating the head landing zone on the carbon substrate with the pulsed laser through the mask material, the surface is roughened and a specific shape is obtained. The magnetic disk of the present invention having a large number of uneven portions (Examples 1 to 1)
4) is CS compared with the magnetic disks of Comparative Examples 1 and 2.
It can be seen that the S characteristic and the GHT characteristic are excellent and the error characteristic is also excellent.

[0048]

According to the method of manufacturing a magnetic recording medium of the present invention, since the irradiation area of the pulse laser can be arbitrarily selected, the zone texture can be easily formed. Further, since it is sufficient to directly irradiate the substrate surface with the pulsed laser, consumables such as a resist and a cleaning liquid are not required, the equipment cost can be reduced, the productivity can be improved, and it is economical. Also,
The magnetic recording medium of the present invention has high durability and abrasion resistance and excellent error characteristics by forming the uneven portion having a specific shape in the head landing zone of the substrate.

[Brief description of drawings]

FIG. 1 is a schematic view showing an apparatus used in an embodiment of a method for manufacturing a magnetic recording medium of the present invention.

2 (a) to 2 (c) are enlarged plan views showing the shape of the main part of the mask material.

FIG. 3 is a schematic cross-sectional view showing the structure of a preferred embodiment of the magnetic recording medium of the present invention.

FIG. 4 is a schematic perspective view showing a shape of an uneven portion.

FIG. 5 is a schematic perspective view (corresponding to FIG. 4) showing another shape of the uneven portion.

FIG. 6 is a schematic cross-sectional view showing a state in which a plurality of uneven portions are overlapped with each other.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic recording medium 12 Non-magnetic substrate 14 Underlayer 16 Magnetic layer 18 Protective layer 20 Lubricant layer 22 Uneven portion 24 Convex contour portion 26 Flat portion 28 Recessed portion 30 Mask material

Claims (6)

[Claims] 1. A method of manufacturing a magnetic recording medium having at least a non-magnetic substrate, a magnetic layer, and a lubricant layer, comprising: a magnetic head and the magnetic recording when starting and stopping the magnetic recording medium on the non-magnetic substrate. To form a large number of irregularities by roughening the surface by selectively irradiating a region including a portion where the medium comes into contact with a pulsed laser through a mask material having an opening of a predetermined shape. And a method for manufacturing a magnetic recording medium. 2. The non-magnetic substrate is a carbon substrate,
The method for manufacturing a magnetic recording medium according to claim 1. 3. A magnetic recording medium having at least a non-magnetic substrate, a magnetic layer, and a lubricating layer, wherein the magnetic head and the magnetic recording medium are in contact with each other when starting and stopping the magnetic recording medium on the non-magnetic substrate. A large number of concavo-convex portions are formed in a region including a region where the concavo-convex portion occurs, and the concavo-convex portion has a lowermost part lower than the center line (JIS B0601) in the region where the concavo-convex portion is not formed. , A convex contour portion surrounding the concave portion and having a highest portion higher than the center line, and the average area per one is 0.1 to 50.
A magnetic recording medium having a size of 0 μm ² and a total area of 50 to 99.8% of the area of the region where the irregularities are formed. 4. The magnetic recording medium according to claim 3, wherein the irregularities have a substantially clover shape or a substantially triangular shape. 5. The magnetic recording medium according to claim 3, wherein the uneven portions are formed so as to overlap each other. 6. A projected area ratio [convex contour portion / (convex contour portion + concave portion)] of the convex contour portion and the uneven portion is 2
The magnetic recording medium according to any one of claims 3 to 5, which is -50%.