JPH11339257A - Manufacture of magnetic record medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the throughput processing capability by providing the mechanism in which two condensing spots are obtained by bisecting laser beams and a bump rack pitch, that is obtained on the surface of a disk in its radial direction, is set arbitrarily. SOLUTION: Laser light beams 2, emitted from a Q switch pulse oscillating type laser oscillator 1, are passed through an expander mirror 3, reflected by a bending mirror 4, made incident on a beam splitter optical system 9, bisected by a half mirror 14, irradiated on a disk 6 as condensed light spots 11 and 10 by processing lenses 18 and 20 and bumps are formed. Thus, the throughput processing capability, that is determined by the repetitive frequency of a Q switch, is practically doubled by bisecting the laser light beams and arbitrarily varying a bump rack pitch Pr. For example, in order to set the bump pitch (radial direction Pr circumferential direction Pθ) to 40 μm/40 μm, an rotating angle θ is adjusted so as to make Pr=40 μm and the amount of the movement for an X stage 8 is set to an 80 μm pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium such as a magnetic disk, and more particularly to a texture processing step using a laser beam for reflecting an uneven surface on a medium surface.

[0002]

2. Description of the Related Art In a fixed magnetic disk drive, when the disk is stopped, the magnetic head slider is in contact with a CSS (contact start / stop) area on the inner peripheral side of the disk. The CSS system which slightly floats from the disk surface by the action and performs an information reading operation or a writing operation in a data area on the outer peripheral side of the disk is mainly adopted.

In the CSS area, head contact sliding, head floating, and head contact sliding are repeatedly performed. Therefore, in order to increase the recording density, it is necessary to rotate the disk at a high speed and reduce the head flying height. In addition, durability and stability of sliding are required. In order to satisfy these requirements, it is required to reduce the coefficient of friction by roughening the disk surface along with the properties of the protective film and the lubricating film on the disk surface.

[0004] The surface roughening treatment of the disk surface is called texture processing, and is to impart a predetermined uneven shape to the substrate surface. Generally, an aluminum substrate is used for a magnetic disk. In recent years, a glass substrate having excellent flatness and rigidity has been used. In the case of an aluminum substrate, mechanical polishing is mainly used as a texture processing method, but in the case of a glass substrate, lithography, etching using a printing technique, or a sputtering technique called a film texture is known. Further, in recent years, dry texturing, which can perform texturing without going through the above-mentioned wet or complicated process, has become the mainstream.

[0005] That is, this dry texture processing is
The laser beam is condensed to form a minute spot, and the surface of the substrate is pulse-irradiated and melted and solidified to generate a bump (uneven portion). A predetermined bump shape can be obtained by selecting a laser type, a wavelength, a laser output, and the like according to the surface material of the substrate. This laser texturing is a technique generally used for an aluminum substrate with a NiP plating film, and various bump shapes can be obtained. FIGS. 3A to 3D are cross-sectional views of various shapes formed with laser bumps. These shapes are determined by a combination of the energy density (or power density) of the laser, the pulse width and wavelength of the laser, the relative speed between the substrate and the laser light, and the like. For example, Ni P
In the case of an aluminum substrate with a plating film, the processing conditions for forming a bump include a laser type of a Q-switch pulse oscillation type of a Nd: YVO ₄ laser, a wavelength of 1.06 μm, a pulse width of 20 to 150 nsec (up to 350 nsec), laser beam focusing spot diameter is 5 to 30 [mu] m, the pulse energy of the laser in the range of 0.5~10μJ / P, the pulse repetition frequency is 10 to 100 kH _Z, a bump diameter phi (FIGS. 3 (a)
In the case of (a), the distance between the protrusion vertices, in the case of FIGS. 3 (b) to (d), the distance between the outermost protrusion vertices) is 4 to 25 μm, and the bump height h (in the case of FIG. 3 (b) to 3 (d), the distance between the substrate surface and the highest protrusion vertex (FIGS. 3 (b) to 3 (d)) is 70 to 1000 °.

FIG. 4 shows a configuration diagram of a conventional laser optical system for performing laser texture at this time. In FIG. 4, 1 is a Q-switch pulse oscillation type laser oscillator, 2 is a laser beam, 3 is an expander lens, 4 is a bend mirror, 5 is a processing lens, 6 is a disk, 7 is a spindle motor, and 8 is an X stage. . A laser beam 2 oscillated from a Q-switch pulse oscillation type laser oscillator 1 passes through an expander lens 3, is converted into a laser beam having an appropriate magnification, is reflected by a bend mirror 4, and is condensed by a processing lens 5. The light is irradiated on the surface of the disk 6 as a minute spot. At this time, the disk 6 is being rotated by the spindle motor 7. At the same time, the spindle motor 7 is moved by the X stage 8 from the inner peripheral side to the outer peripheral side of the disk 6. Thus, the tracks of the bumps are formed by winding the laser bumps obtained by the laser beam irradiation. At this time, the pitch of the bumps in the radial direction and the circumferential direction (distance between the bumps) is usually determined by the moving speed of the X stage 8 and the rotating speed of the disk 6. Here, when forming the bump pitch (radial direction: Pr / circumferential direction: Pθ), for example, the bump diameter φ is 10 μm and the bump height h is
The 230 Å, the bump pitch 40 [mu] m / 50 [mu] m, when it is 70 kH _Z and optimize pulse repetition frequency of the Q switch, the throughput for the laser bump forming the disk, the Q-switched pulse repetition frequency 70
It will determined by the kH _Z. That is, in a fixed CSS region and a constant bump pitch, it depends on how high-speed a pulse is formed. However, in order to increase the throughput, it is necessary to increase the pulse repetition frequency without changing the laser output condition per pulse of the laser. However, in a Q-switch oscillation type laser, when the pulse repetition frequency is increased, the laser output condition is increased. Cannot be easily changed because it changes. In addition, the bump pitch cannot be easily widened due to the friction characteristics and the attraction force characteristics of the CSS region. Usually, the throughput for bump formation is bump height,
Bump diameter, since the determination of the bump pitch has priority (optimum conditions of laser output of bump formation), the pulse repetition frequency of the result in that case is, for example, 30 kH _Z, 70 k
H _Z, determined as that 90 kH _Z. Therefore, 90 k
If _HZ is determined, this is the maximum throughput. Of course, to improve the throughput, it is conceivable to increase the handling speed when exchanging disks, but the handling speed is usually set to the level of the maximum speed that can be processed.

[0007]

As described above, when the laser bump forming conditions are optimized, the throughput throughput is determined by the Q switch pulse repetition frequency. Maximum capacity of pulse repetition frequency of the Q-switch oscillation on the market is a limit 100 kH _Z position,
If the speed is further increased, the stability of the laser output decreases, which is not preferable in bump formation.

In view of the above problems, an object of the present invention is to provide a method of manufacturing a magnetic recording medium which improves throughput in texture processing for forming bumps using a Q-switch pulse oscillation type laser beam. It is in.

[0009]

According to the present invention, there is provided a light splitting optical system for splitting a laser beam from a Q-switch pulse oscillation type laser oscillator into two, and a laser beam splitting the laser light. A laser optical system mechanism for simultaneously obtaining two condensed spots on the surface of the magnetic recording medium substrate to form bumps, and a magnetic recording medium substrate rotating and moving mechanism having a stage for rotating and moving the magnetic recording medium substrate. The laser bumps are formed by providing them. The light splitting optical system includes an optical system that splits a laser beam into two by a half mirror (or a polarizing beam splitter) and condenses the laser beam with two processing lenses, and an optical axis of the laser beam incident on the light splitting optical system. And the other processing lens through the bend mirror by reflecting the half mirror around a basic central axis that is made to coincide with the optical axis of the laser light that has passed through one processing lens through the half mirror. It is possible to arbitrarily rotate and move the optical axis with the distance to the other optical axis passing therethrough as a radius.

As a result, it is possible to substantially double the throughput.

[0011]

FIG. 1 is a block diagram of a laser optical system showing an embodiment of the present invention. In FIG. 1, 9
Is a light splitting optical system, 10 and 11 are condensed spots, 14 is a half mirror, 19 is a bend mirror, 18 and 20 are processed lenses, and other components are the same as those in FIG. is there. The difference from FIG. 4 is that the light splitting optical system 9
Is provided. A laser beam 2 from a Q-switch pulse oscillation type laser oscillator 1 passes through an expander mirror 3, is reflected by a bend mirror 4, enters a light splitting optical system 9, is split into two by a half mirror 14, and is processed into a lens. 1
8 and 20, the condensed spots 11 and 10 on the disc 6
To form a bump.

FIG. 2 is a view showing details of a light splitting optical system according to the present invention. FIG.
(B) is the figure which removed the upper plate and mirror of the outer box seen from just above the outer box. In FIG. 2A, 12 is an outer box,
13 is a hole, 15 is a passing laser beam, 16 is a reflected laser beam,
Reference numeral 17 denotes a basic central axis, and other components are the same as those in FIG. 1 and are denoted by the same reference numerals. The laser beam 2 enters through the hole 13 of the outer box 12 of the light splitting optical system 9 and the half mirror 1
4 (or a polarizing beam splitter) splits the laser beam into a passing laser beam 15 and a reflected laser beam 16. The optical axis of the passing laser light 15 and the optical axis of the laser light 2 coincide with each other and are the same axis, which is referred to as a basic central axis 17. The passing laser light 15 passes through the processing lens 18 and is focused on the disk surface. The reflected laser light 16 is a bend mirror 19,
The light is focused on the disk surface via the processing lens. Here, the outer case 12 is configured to be rotatable about the basic central axis 17 with the radius r between the reflected laser beam 16 from the bend mirror 19 and the basic central axis 17 as the radius.

In FIG. 2B, reference numerals 23 and 24 denote bump tracks, and other components are the same as those in FIG. The condensed spots 11 and 10 condensed by the processing lenses 18 and 20, respectively, form bumps on the bump tracks 23 and 24, respectively. The distance between the bump tracks 23 and 24 forms the radial pitch Pr. This means that the outer case 12 is
Is rotated so that the pitch Pr is set.

As described above, since the laser beam is divided into two and the radial bump rack pitch Pr can be changed arbitrarily, the repetition frequency of the Q switch is determined as in the prior art. The throughput throughput can be substantially doubled. For example, the bump pitch (Pr in the radial direction / Pθ in the circumferential direction) is set to 40 μm /
In the case of setting to 40 μm, the rotation angle θ is adjusted so that Pr = 40 μm, and at the same time, the X stage 8 (see FIG. 1)
May be set so as to have a pitch of 80 μm. Here, the mechanism for adjusting the rotation angle θ of the outer case 12 may be a mechanism combining the gear and the servomotor or a manual gear mechanism with a micrometer as a mechanism centered on the basic central axis 17.

In this embodiment, the laser bump forming method is performed only from one side, but it goes without saying that the present embodiment can be applied as it is even to a simultaneous processing method for both sides of the disk. In addition, even if the processing lens in the light splitting optical system is an autofocus type, it can be handled by using a half mirror and a bend mirror as polarization mirrors.

[0016]

According to the present invention, a laser beam is divided into two parts to obtain two condensed spots with two processing lenses, and at the same time, the radial bump track pitch obtained on the disk surface is reduced. By adopting a mechanism that can be set arbitrarily, the throughput throughput is substantially doubled as compared with the conventional laser bump forming method.

In this embodiment, a Q-switched pulse oscillation type laser oscillator has been described as an example. However, if the advantage of obtaining two condensed spots of two light beams is used, for example, a continuous oscillation type EOM (electrical It is needless to say that high-speed operation can be achieved even by using a pulsed laser oscillator (modulation by optical effect).

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser optical system showing an embodiment of the present invention.

FIG. 2 is a diagram showing details of a light splitting optical system according to the present invention;
(A) is an overall configuration diagram in which a side plate of an outer box is deleted, and (b) is a diagram in which an upper plate and a mirror of the outer box are removed from directly above the outer box.

FIG. 3 is a sectional view of various shapes formed with a laser bump.

FIG. 4 is a configuration diagram of a laser optical system showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Q switch pulse oscillation type laser oscillator, 2 ... Laser light, 3 ... Expander lens, 4,19 ... Bend mirror, 6 ... Disk, 7 ... Spindle motor, 8 ... X stage, 9 ... Light splitting optical system, 10 , 11 ... Condensing spot,
12 ... outer box, 13 ... hole, 14 ... half mirror, 15 ... passing laser light, 16 ... reflected laser light, 17 ... basic central axis,
18, 20: processed lens, 23, 24: bump track.

Claims (2)

[Claims] 1. A light splitting optical system for splitting a laser beam from a Q-switch pulse oscillation type laser oscillator into two, and two condensed spots are simultaneously obtained on the surface of a magnetic recording medium substrate by the split laser light. Magnetic recording medium characterized by forming a laser bump by providing a laser optical system mechanism for forming a bump by means of a magnetic recording medium, and a magnetic recording medium substrate rotating and moving mechanism having a stage for rotating and moving the magnetic recording medium substrate. Manufacturing method. 2. A light splitting optical system, comprising: an optical system for splitting a laser beam into two by a half mirror and condensing the laser beam by two processing lenses; and an optical axis of the laser beam incident on the light splitting optical system. Reflecting the half mirror and passing through the other processing lens through the bend mirror, centering on the basic central axis which is made to coincide with the optical axis of the laser beam transmitted through the half mirror and passing through one processing lens 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium can be arbitrarily rotated and moved with a distance from the other optical axis as a radius.