JPH1049865A - Method and apparatus for surface treatment of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus which prevent a beam of laser light form being propagated in the air, in which the surface treatment time of a magnetic recording medium is shortened, and in which the magnetic recording medium is treated safely by dividing the beam of laser light from a light source into a plurality of beams of energy light and forming a protrusion via a lens at a specific position. SOLUTION: In a magnetic recording medium, a substrate layer, an intermediate layer and a magnetic layer are formed on a nonmagnetic substrate, and, in addition, a protective film layer and a lubricant layer are formed on the magnetic layer. The substrate and the surface of any arbitrary layer are irradiated with a beam of energy light at a wavelength of 300nm or shorter, a protrusion is formed, and a surface treatment is executed. At this time, the beam of energy light is radiated by a lens 1, and it is output via spectroscopes 3, 31, 32 as dividing means which divide the beam into a plurality of beams of energy light and via optical fibers 21 to 23. Then, a lens 5 is arranged in a position so as to be divided at (a):(b) when the spot diameter of the radiated beam of energy light is designated as (a) and a distance up to a face to be irradiated is designated as (b). As a result, it is possible to prevent the beam of energy light from being propagated in the air, the surface treatment time of the magnetic recording medium can be shortened, and the magnetic recording medium can be treated safely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a magnetic recording medium employing a contact start and stop (CSS) method. In particular, the present invention relates to a surface treatment method and a surface treatment apparatus for a magnetic recording medium that realize sticking characteristics of the magnetic head to the recording medium surface and low flying height of the magnetic head while maintaining good CSS characteristics.

[0002]

2. Description of the Related Art Normally, recording / reproducing of information on a magnetic disk is performed via a magnetic head. At this time, the magnetic disk rotates at a high speed to float the magnetic head. When the magnetic disk is not rotating, the magnetic head is stationary in contact with the magnetic disk in a contact start and stop (CSS) area.

[0003]

In such a magnetic disk, a non-magnetic material such as NiP plating applied to the substrate surface or the substrate surface is used to prevent sticking (sticking) of the magnetic head and to improve magnetic characteristics. In many cases, a surface treatment (hereinafter, referred to as a mechanical texture treatment) for providing a processing mark by mechanical polishing is performed on the surface of the underlayer made of.

However, when the linear recording density and the track density are increased due to the increase in the amount of information and the size and weight of the device, and the area per pit is reduced, the processing marks due to the mechanical texture as in the prior art are reduced. Thus, the probability of causing an error during information reproduction increases.

Therefore, a method has been proposed in which mechanical texture processing is performed only on the CSS area where the magnetic head is stationary, and the information recording area is left as it is. However, in this case, since the surface of the information recording area is higher than the surface of the CSS area, and it is difficult to make the step smooth, the magnetic head crashes when passing through the step. Had the problem of doing

As a surface treatment method other than mechanical texture processing, there has been proposed a method of forming concentric projections having an area ratio of 0.1 to 5% with respect to the entire surface of a magnetic disk by photolithography (see, for example, Japanese Patent Application Laid-Open No. H11-157556). Proceedings of the Japan Society of Lubrication Tribology, 1991-5, A-11 and 1
992-10, B-6).

However, in this method, since the apexes of the projections have a planar shape, the contact area with the magnetic head is large, so that the friction increases with the number of times of sliding of the magnetic head, and it is difficult to industrialize. is there.

On the other hand, a highly uniform surface state can be realized,
As a technique that can be easily controlled, a method of performing texture processing using a laser beam has also been proposed. For example, U.S. Patent Nos. 5,062,021 and 5,108,781
Nos., Etc., with Nid-YAG strong pulse laser light
By locally melting the P layer, the diameter of the concave hole formed by melting and the surrounding NiP raised by surface tension and solidified by the surface tension is 2.5 to 10 mm.
Make a number of crater-shaped irregularities consisting of a 0 μm rim,
Attempts have been made to improve the CSS characteristics with a magnetic head by using an annular convex rim.

The inventors of the present invention have studied a method of manufacturing a magnetic recording medium using an energy beam such as a laser, for example, as disclosed in JP-A-8-77554 and JP-A-8-77554.
Various methods have been proposed as disclosed in US Pat.

[0010] However, these methods are dangerous when energy beams are propagated in the air and are in danger of touching the body by mistake, and many optical components are necessary for polarization and refraction. Had many restrictions. Also, there are restrictions on the division of energy rays, such as the necessity of many optical components for dispersing the energy rays into a plurality of energy rays. Furthermore, when an ultraviolet ray is used as the energy ray, there is a problem that it is particularly difficult to take safety measures.

[0011]

Therefore, the stable flying height of the magnetic head in the data recording area of the magnetic disk can be made sufficiently low as defined by the glide of the data recording area. It is desired that the magnetic head be stopped on a protrusion having an appropriate height so that sticking does not occur.
In addition, there is also a strong demand for safety against energy rays, simplicity of handling, and high-speed processing using a plurality of energy rays.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to a method for manufacturing such a medium for high-density magnetic recording. The gist of the present invention is that at least an underlayer and a magnetic layer are formed on a non-magnetic substrate. A substrate of a magnetic recording medium in which a protective film layer and a lubricating layer are sequentially formed on an intermediate layer and / or a magnetic layer provided between the underlayer and the magnetic layer, or the surface of any of these layers A surface treatment method for forming projections by irradiating energy beams on a magnetic recording medium, wherein the energy rays are divided into a plurality of energy rays and a plurality of projections are simultaneously formed; A magnetic recording system comprising a substrate, at least a base layer and a magnetic layer, and a protective film layer and a lubricating layer formed in that order on an intermediate layer and / or a magnetic layer provided between the base layer and the magnetic layer. Media base Alternatively, in a surface treatment apparatus that forms projections by irradiating the surface of an arbitrary layer with an energy beam, a dividing unit that divides the energy beam into a plurality of energy beams, and a spot diameter of the energy beam at the time of emission from the dividing unit. a, when the spot diameter on the irradiated surface is b, the distance from the exit end of the dividing means to the irradiated surface is a: b
And a means for scanning the plurality of energy rays relative to a surface to be illuminated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, as the substrate of the magnetic recording medium, a non-magnetic substrate such as an aluminum alloy plate or a glass substrate is usually used, but a metal substrate such as copper or titanium, a ceramic substrate, a resin substrate, or a silicon substrate may also be used. it can. The thermal conductivity of the substrate is important from the viewpoint of cooling of heat by irradiation with energy rays, and is preferably 100 Watt /
mK or less. The film thickness is usually 20 to 20 on a non-magnetic substrate.
An underlayer of 0 nm Cr or Cu is provided, and in some cases, the film thickness is usually 100 to 100 mm between the substrate and the above layer.
An underlayer of 20,000 nm made of a nonmagnetic material such as a NiP alloy may be provided.

The underlayer is usually formed by an electroless plating method or a sputtering method. The thermal conductivity of the underlayer and the thickness of the layer are also important from the viewpoint of cooling of heat by irradiation with energy rays. The thermal conductivity is preferably 100 Watt / mK or less, and the layer thickness is preferably 50 to 30,000 n.
m, particularly preferably 100 to 15,000 nm.

The magnetic recording layer is formed by a method such as electroless plating, electroplating, sputtering, or vapor deposition.
P, Co-Ni-P, Co-Ni-Cr, Co-Ni-
Pt, Co-Cr-Ta, Co-Cr-Pt, Co-C
A ferromagnetic alloy thin film such as an r-Ta-Pt-based alloy is formed, and its thickness is usually about 30 to 70 nm.

A protective layer is usually provided on the magnetic recording layer. The protective layer may be formed by a method such as vapor deposition, sputtering, plasma CVD, ion plating, or a wet method. Carbide films such as TiC and SiC, nitride films such as SiN and TiN, etc., SiO, Al
An oxide film of O, ZrO, or the like is formed. Of these, carbon films and hydrogenated carbon films are particularly preferred. Further, the ratio of hydrogen as a main component (H / C, atomic number%) is 0.1 to 40 at%, and particularly 1 to 40 at%. 30at
% Hydrogenated carbon film is preferred.

Further, a lubricant layer is usually provided on the protective layer. However, when a magnetic head having a diamond-like carbon layer on the slider surface is used, it is not always necessary to provide a protective layer because tribological properties with the medium are improved.

The energy ray source used in the manufacturing method of the present invention is not particularly limited, but an Nd: YAG laser or an Ar laser is suitable. The laser is subjected to an electro-optic effect and modulated to obtain a desired pulse width. Alternatively, a desired energy ray is obtained by a method such as conversion to a desired wavelength using an SHG (second harmonic generator), FHG (fourth harmonic generator), or the like.

In the production method of the present invention, such energy rays are irradiated onto the surface of the substrate or any of the above-mentioned layers to form projections having excellent CSS characteristics. When a projection is formed by irradiating the substrate or the underlayer with energy rays, mechanical texture processing may be performed before forming the magnetic layer.

In the present invention, the energy beam from the light source is divided into a plurality of energy beams for use. There are various methods of dividing the energy beam, such as 1) a method of connecting an optical fiber and a spectroscope in multiple stages, 2) a method of using an optical waveguide having one input and multiple outputs, and 3) a method of connecting a spectroscope having optical fibers joined in multiple stages. A method can be adopted.

FIG. 1 is a diagram showing an example of a configuration in which an optical fiber and a spectroscope are connected in multiple stages as energy beam splitting means. This example shows a case where the energy ray is divided into eight. Laser light generated from a light source (not shown) enters the imaging lens 1 and is collected so as to have a spot diameter smaller than the diameter of the optical fiber 2. A 1: 2 spectroscope 3 is connected to the other end of the optical fiber 2, and the laser light is split into two. Optical fibers 21 are connected to the output terminals of the spectroscope 3 respectively. The other end of the optical fiber 21 is further connected to a 1: 2 spectroscope 31 to split the laser light into two again. Similarly, the optical fiber 22, the spectroscope 3
2 and the optical fiber 23 are connected and divided into eight energy rays as a whole.

The end of the optical fiber 23 is attached to a fiber attachment jig 4 for positioning. The imaging lens 5 for condensing the energy ray from the optical fiber 23 for the processing, when the spot diameter of the energy ray emitted from the optical fiber 23 is a and the desired beam diameter is b, from the exit to the imaging lens. And the ratio of the distance B between the imaging lens and the irradiation surface is a: b.

The optical fiber to be used may be any one having a high light-collecting efficiency. The material is not particularly limited, but an optical fiber made of quartz can be suitably used.

FIG. 2 is a diagram showing an example of a configuration using a one-input multi-output optical waveguide as the energy ray dividing means.
Various optical waveguides, such as those formed using a substrate made of a dielectric material, a compound semiconductor, or the like, can be used.

FIG. 2A shows an optical waveguide 1 having one input and eight outputs.
It is a figure showing the example of composition using 0. Laser light from a light source (not shown) is condensed by the imaging lens 1 so that the spot diameter is smaller than that of the entrance of the optical waveguide 10. The condensed laser light is split into eight by the optical waveguide 10 and emitted from the exit of the optical waveguide 10. Then, the light is converged to a desired spot diameter by the imaging lens 5 corresponding to each of the eight laser beams, and reaches the surface to be irradiated.

The imaging lens 5 divides the distance from the exit port to the substrate into a: b, where a is the exit aperture of the optical waveguide, and b is the spot diameter when finally irradiating the surface to be irradiated. Place in position.

In the case of FIG. 2 (a), the output aperture of the optical waveguide is 1
The coupling lens 5 is arranged at a position where the distance from the emission port to the surface to be irradiated is divided 10: 1 so that the laser beam of 0 μm has a diameter of 1 μm on the surface to be irradiated.

In the configuration shown in FIG.
The laser light condensed in step (1) is directly input to the optical waveguide 10 and propagates in the air from the optical waveguide 10 to the imaging lens 5, but between the coupling lens 1 and the optical waveguide 10 and the optical waveguide. An optical fiber may be connected between the imaging lens 10 and the imaging lens 5 (FIG. 2B). When this configuration is adopted, the imaging lens 1 focuses the laser light to a diameter smaller than the diameter of the optical fiber 2. The position of the imaging lens 5 is determined by the ratio of the diameter a of the optical fiber 25 connected to the exit of the optical waveguide 10 to the spot diameter b on the irradiated surface.

FIG. 3 shows an example of the overall configuration of the surface treatment apparatus. That is, the laser light from the light source 50 propagates through the optical fiber or the air and enters the energy beam splitting means 12. The energy beam splitting means 12 is arranged movably, for example, along a rail 14. The substrate 30 to be irradiated is attached to the spindle 11 and rotates at a predetermined rotation speed. Then, the laser beam is applied to the irradiated surface while moving the energy beam splitting means 12 along the rail 14 at a predetermined relative speed with respect to the rotating substrate, and a plurality of projections are simultaneously formed.

In the present invention, there is no particular limitation on the optical fiber that can be used, but it is preferable that the optical fiber has a shape that reduces the attenuation and enhances the light collection efficiency. The material is not particularly limited, but a material made of quartz or the like is preferable.

Hereinafter, specific experimental examples will be described. (Experimental example 1) NiP (thermal conductivity, about 10 Watt / m) having a thickness of 10 μm was formed on a disk-shaped glass substrate having a diameter of 95 mm.
After plating K), the surface was polished so that the surface roughness Ra was 2 nm or less, to obtain a substrate having a NiP underlayer.

Next, an intensity of 163 mW at the time of emission from the light source, an average irradiation time of 0.6 μsec, and an aperture ratio NA of the objective lens used for condensing the laser are 84% (1 / e) of the energy.
² ) A mode-locked Nd: YAG laser having a spot diameter (1.22 × λ / NA) of 1.0 μm where the concentration of the laser beam was concentrated, and a laser beam having a pulse width of 1 ns and a repetition frequency of 10 MHz was taken out.

After the laser light is electro-optically modulated,
By using FHG, a laser beam having a wavelength of 266 nm (ultraviolet region wavelength), a pulse group region of 100 ns, and a repetition period of a pulse existence region and a non-existence region of 1 μs is extracted. Here, the pulse group refers to a collective area of short pulses.

This laser beam was incident on the energy beam splitting means having the structure shown in FIG. 1 and split into eight. The diameter 100 of the optical fiber into which the laser beam is incident is set to 100 μm,
The energy beam was attached to a fiber attachment jig such that the interval between the energy beams was 10 μm. The position was adjusted so that the distance between the imaging lens and the irradiation surface was 1 with respect to the distance 10 between the energy beam outlet and the imaging lens.
1 μm in diameter at a substrate linear velocity of 1714 cm / sec
Are formed at a time, and this is repeated while moving the energy beam dividing means relative to the substrate.
NiP in the CSS area with a radius of 18 to 21 mm on the inner periphery of the substrate
Spirals having a pitch of 10 μm were formed on the base surface.

After the formation of the protrusions, circumferential mechanical texturing was performed using free diamond abrasive grains having a particle size of about 1 μm. FIG. 4 shows a surface profile after laser processing of the textured surface profile by laser interference (“ZYG” manufactured by Zigo USA).
O "). FIG. 4A is a three-dimensional representation, and FIG. 4B is a diagram showing a cross-sectional shape when the projection is cut along a plane passing through the apex and perpendicular to the substrate. FIG. 4 shows that the protrusion is suitable for the CSS characteristics.

Next, a Cr intermediate layer (100 nm), a Co—Cr layer were sequentially formed on the NiP substrate by sputtering.
-A Ta alloy magnetic film (50 nm) was formed. Further, a carbon protective film (20 nm) is formed, and then a fluorine-based liquid lubricant (“DO” manufactured by Monte Edison Co., Ltd.) is formed by an immersion method.
L-2000 ") was applied to a thickness of 2 nm to produce a magnetic recording medium.

(Experimental Example 2) Disc A having a diameter of 95 mm
A magnetic recording medium was prepared in the same manner as in Experimental Example 1 except that the L substrate was used, and the same evaluation was performed. As a result, it was confirmed that the same protrusions as those in Experimental Example 1 were formed.

(Experimental example 3) Experimental example 1 except that the configuration shown in FIG.
A magnetic recording medium was formed in the same manner as described above and evaluated. An optical waveguide made of quartz glass was used. FIG. 5 shows the result of observing the surface shape after texture processing with a surface shape measuring apparatus (“ZYGO” manufactured by Zigo, USA) using laser interference. FIG. 5A is a three-dimensional representation, and FIG. 5B is a diagram illustrating a cross-sectional shape when the protrusion is cut along a plane passing through the apex and perpendicular to the substrate. FIG. 5 shows that the protrusion is suitable for the characteristics of CSS.

(Experimental Example 4) Disk-shaped A having a diameter of 95 mm
A magnetic recording medium was prepared in the same manner as in Experimental Example 3 except that the L substrate was used, and the same evaluation was performed. As a result, it was confirmed that the same protrusions as those in Experimental Example 3 were formed.

(Experimental Example 5) A magnetic recording medium was formed and evaluated in the same manner as in Experimental Example 3 except that the energy ray dividing means having the configuration shown in FIG. 2B was used.
The diameter of the optical fiber was 100 μm on the entrance side and 10 μm on the exit side. As a result, it was confirmed that the same protrusions as those in Experimental Example 3 were formed.

[0041]

As described above, according to the surface treatment method of the present invention, a laser beam emitted from a light source is divided into a plurality of laser beams to form projections, so that the time required for the treatment is greatly reduced. it can. Furthermore, by adopting a configuration in which the laser light is propagated using an optical fiber or an optical waveguide, the laser light can be prevented from propagating in the air as much as possible. In the case of using, for example, there is an effect that a particularly useful surface treatment apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a first view of an energy ray dividing means used in the present invention.
The figure which shows the example of a structure.

FIG. 2 shows a second example of the energy ray dividing means used in the present invention.
The figure which shows the example of a structure.

FIG. 3 is a diagram showing a configuration of a surface treatment apparatus according to the present invention.

FIG. 4 is a view showing a shape of a projection formed by the surface treatment apparatus of the present invention.

FIG. 5 is a view showing a shape of a projection formed by the surface treatment apparatus of the present invention.

[Explanation of symbols]

 1,5 imaging lens 2,21,22,23,25 optical fiber 10 optical waveguide

Claims (6)

[Claims] 1. A protective film layer and a lubricating layer are sequentially formed on at least an underlayer and a magnetic layer on a non-magnetic substrate, and on an intermediate layer and / or a magnetic layer optionally provided between the underlayer and the magnetic layer. In the surface treatment method of irradiating the surface of the substrate of the magnetic recording medium or any of these layers with energy rays to form projections, the energy rays are divided into a plurality of energy rays, and the plurality of projections are simultaneously formed. A method for treating a surface of a magnetic recording medium, comprising: 2. A protective film layer and a lubricating layer are sequentially formed on at least an underlayer and a magnetic layer on a non-magnetic substrate, and optionally on an intermediate layer and / or a magnetic layer provided between the underlayer and the magnetic layer. In a surface treatment apparatus for irradiating a surface of a substrate or an arbitrary layer of a magnetic recording medium formed with an energy beam with an energy beam to form a projection, a dividing device for dividing the energy beam into a plurality of energy beams; Assuming that the spot diameter of the energy ray at the time of the irradiation is a and the spot diameter on the irradiation surface is b, a plurality of positions arranged at positions dividing the distance from the emission end of the dividing means to the irradiation surface are a: b. A surface treatment apparatus for a magnetic recording medium, comprising: an imaging lens; and means for scanning the plurality of energy rays relative to a surface to be irradiated. 3. The energy beam according to claim 2, wherein the energy beam is a laser beam having a wavelength of 300 nm or less.
A surface treatment apparatus for a magnetic recording medium according to claim 1. 4. The apparatus according to claim 2, wherein said dividing means has a configuration in which an optical fiber and a spectroscope are connected in multiple stages. 5. The method according to claim 1, wherein the dividing means has one input and n outputs (n is 2
3. The surface treatment apparatus for a magnetic recording medium according to claim 2, comprising an optical waveguide of (the above integer). 6. An apparatus according to claim 2, wherein said dividing means comprises a beam splitter and a mirror.