JPH10283632A - Magnetic disk, magnetic disk device and generating method of molding stamper for magnetic disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a stable floating attitude during the movement of a head slider by forming a projecting and recessed section on the surface of a medium to record information, forming projecting pit columns at the inner or the outer peripheral sections of the projecting and recessed section and making the heights of the section above and the pit columns to be different. SOLUTION: In a CSS zone 3d, rectangular shaped pit columns 3p are formed in a concentric circular ring shape. In a data zone 3b, a projecting and recessed section, i.e., projecting shaped data tracks 3t and recessing shaped guard bands 3g are formed in a concentric circular ring shape. In order to make the floating height of the head slider to be 50 nm, the ratio of the area of the projecting section formed in the zone 3b of a magnetic disk and the area of the recessed sections to be 2:1. In order to eliminate the change in the attitude of the head slider while it is moving from the zone 3a to the zone 3b, the heights of the pits 3p are made higher than the heights of the tracks 3t for the amount of 10 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk for recording and reproducing information by a magnetic recording method, a magnetic disk drive using the magnetic disk, and a method of forming a stamper for molding a magnetic disk substrate of the magnetic disk. It is.

[0002]

2. Description of the Related Art The density of magnetic disks has been increasing year by year, and has recently been increasing at a rate of 60% / year. This increase in density is due to the MR head
This is possible by adopting a head or improving the material of the magnetic medium of the magnetic disk. In addition, the distance (spacing) between the magnetic disk and the magnetic head is reduced, for example, a value smaller than 50 nm. This is also possible.

In order to achieve such spacing, the surface of the magnetic disk must have a surface roughness equal to or less than the spacing, for example, a mirror surface. However, a conventional magnetic disk device employs a so-called CSS (contact start / stop) in which the magnetic disk and the head slider on which the magnetic head is mounted are in contact with each other at the time of start and stop. When the surface of the magnetic disk is mirror-finished, the area of true contact between the magnetic disk and the head slider increases, causing stiction.

In order to achieve both the mirror finishing of the magnetic disk and the CSS, a recent magnetic disk device has a magnetic disk and a head slider on which a magnetic head is mounted in addition to an information recording area (data zone). A contact area (CSS zone) for contact is provided. That is, the data zone in which data is read / written is mirror-finished, and the CSS zone in contact with the head slider is roughened (textured) so that stiction does not occur.
The mirroring of the magnetic disk and CSS are compatible. As a texturing method, a polishing method of polishing the surface of the magnetic disk substrate in the CSS zone with a polishing tape is generally used.

However, when this method is used, the average height plane (flying height reference plane) of the CSS zone is lower than the average height plane (flying height reference plane) of the data zone. Therefore, CS
There is a disadvantage that the head slider floating in the S zone may be inclined when moving from the CSS zone to the data zone, or may crash in an extreme case.

In order to solve this drawback, there has been proposed a method in which a magnetic disk substrate is formed of aluminum and the surface of the magnetic disk substrate in the CSS zone is irradiated with a laser beam to form a crater-shaped projection. ("Lase
r Texturing for low-fly-h
right media ", R. Ranjan, JA
ppl. Phys. 69 (8), 15 April 1
991). In this method, the average height surface (flying height reference surface) of the CSS zone is adjusted by adjusting the density of the protrusions.
And the average height plane (flying height reference plane) of the data zone can be adjusted, so that the movement of the head slider from the CSS zone to the data zone can be performed without any obstacle.

However, when a convex portion is formed in the CSS zone of the magnetic disk, it can be applied to a magnetic disk composed of an opaque magnetic disk substrate made of metal or the like which does not transmit laser light. However, there is a problem that the method cannot be applied to a magnetic disk made of a transparent magnetic disk substrate such as glass or resin.

Therefore, as a method for forming a convex portion in a CSS zone even on a magnetic disk formed of a transparent magnetic disk substrate, an injection molding method using a stamper used for an optical disk or the like has been proposed. In this method, first, a concave depression is formed in a region of a stamper corresponding to a region where a convex portion of a CSS zone on a magnetic disk substrate is formed, and a resin is injection-molded using the stamper. As a result, the resin is filled in the concave depression, so that the convex portion (convex pit row) is formed in the CSS zone on the magnetic disk substrate.
Can be formed.

[0009]

The magnetic disk substrate formed by the stamper described above has no problem when applied to a magnetic disk in which the data zone is formed smooth (flat). When the present invention is applied to a discrete type magnetic disk formed as a (discrete) type, there are the following problems. That is, the information is recorded on the largest possible area on the discrete magnetic disk, so that the recording / reproducing accuracy is improved. Therefore, in the data zone, the area of the projection is larger than the area of the recess. Is formed.

[0010] The height of the pits in the CSS zone and the height of the projections in the data zone formed on such a discrete magnetic disk are determined by the thickness of the resist applied when the stamper is formed. Become. Therefore, if the flying height of the head slider in the CSS zone is made equal to the flying height of the head slider in the data zone, the load capacity (the area of the protrusion contributing to the flying of the head slider) is the same in the CSS zone and the data zone. Therefore, there is a problem that the real contact area between the head slider and the pits increases, and the head slider tends to stick.

Conversely, if the area of the pit is reduced in order to prevent sticking of the head slider, the load capacity in the CSS zone is reduced and the flying height of the head slider is reduced, and the head slider moves from the CSS zone to the data zone. There has been a problem that the posture change during movement becomes large, and in extreme cases, the head slider may crash.

The present invention has been made in view of the above-mentioned circumstances, and has a magnetic field having an appropriate contact area of a head slider, and having a small attitude change of the head slider when moving from the contact area to the information recording area. It is an object of the present invention to provide a disk, a magnetic disk device using the magnetic disk, and a method of forming a stamper for molding a magnetic disk substrate of the magnetic disk.

[0013]

According to the present invention, an uneven portion for recording information is formed on a surface, and a convex portion for contacting a head slider with an inner peripheral portion or an outer peripheral portion thereof is provided. A magnetic disk in which a pit row having a shape is formed, which is achieved by making the height of the uneven portion different from that of the pit row.

According to the above configuration, the height of the pit row in the contact area is different from the height of the uneven portion in the information recording area.
When the head slider moves from the contact area to the information recording area, a stable flying attitude can be maintained, and the reliability of the magnetic disk can be improved.

[0015]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 is a perspective view showing a configuration example of a hard disk drive which is an embodiment of the magnetic disk drive of the present invention. The hard disk drive 1 is provided with a spindle motor 9 disposed behind a plane portion of a housing 2 formed of an aluminum alloy or the like, and a magnetic disk 3 driven to rotate at a constant angular velocity by the spindle motor 9. Have been. Further, an arm 4 is swingably attached to the housing 2 around a pivot 4a. A voice coil 5 is attached to one end of the arm 4, and a head slider 6 is attached to the other end of the arm 4.

On the housing 2, magnets 7a and 7b are mounted so as to hold the voice coil 5.
A voice coil motor 7 is formed by the voice coil 5 and the magnets 7a and 7b. Head slider 6
Are formed on both sides of the lower surface thereof with rails acting as air bearing surfaces, and tapered portions are formed on the tip side of these rails. And
A magnetic head 8 is mounted on the rear end surface of one of the rails.

In such a configuration, when the spindle motor 9 is driven, the magnetic disk 3 rotates at a constant angular velocity. Then, when air flows in from the tapered portion on the tip end side of the rail of the head slider 6 with the rotation of the magnetic disk 3, the air flows along the rail. And
When this air flows out from the rear end side of the rail, the head slider 6 flies at a minute interval (floating amount) from the surface of the magnetic disk 3 due to the levitating force. That is, the head slider 6 flies due to an increase in pressure due to the gap between the head slider 6 and the surface of the magnetic disk 3 decreasing from the leading end toward the trailing end in the running direction.

When a current is externally supplied to the voice coil 5, the arm 4 moves around the pivot 4a based on the magnetic field of the magnets 7a and 7b and the force generated by the current flowing through the voice coil 5. Rotate. As a result, the head slider 6 attached to the other end of the arm 4 moves substantially in the radial direction of the magnetic disk 3 while flying above the surface of the magnetic disk 3 as the magnetic disk 3 rotates. Therefore, the magnetic head 8 mounted on the head slider 6 performs a seek operation on the magnetic disk 3 to record and reproduce information.

FIG. 2 is a plan view showing an embodiment of the magnetic disk of the present invention, FIG. 3 is a perspective view of its surface, and FIG.
It is the sectional side view. This magnetic disk 3 uses a magnetic disk substrate made of resin, has an annular CSS zone 3a on the outer peripheral side, and has an annular data zone 3b on the inner peripheral side of the CSS zone 3a. I have.
Then, as shown in FIGS. 3 and 4, the CSS zone 3a
, A row of rectangular convex pits 3p is formed in a concentric annular shape. In the data zone 3b, an uneven portion (discrete), that is, a convex data track 3t is provided.
And a concave guard band 3g is formed in a concentric annular shape. The CSS zone 3a may be provided in an annular shape on the inner peripheral side of the magnetic disk substrate. The shape of the pit 3p can be arbitrarily selected, such as a columnar shape.

The magnetic disk substrate of the magnetic disk 3 can be prepared by an injection molding method using a stamper used for an optical disk or the like. Therefore, since a large number of magnetic disk substrates can be formed from one stamper, there is almost no variation in texture, and the steps of texture inspection and management performed for each sheet can be omitted.

Here, the flying height of the head slider 6 and the height of the magnetic disk 3 are determined in order to determine the formation ratio and height of the unevenness that can ensure the flying stability of the head slider 6 in the CSS zone 3a and the data zone 3b. Ratio between the area of the convex part and the area of the concave part (area of the convex part / area of the concave part)
FIG. 5 shows the result of examining the relationship with. By the way, in order to prevent the head slider 6 from sticking to the CSS zone 3a of the magnetic disk 3, the ratio of the area of the convex portion formed in the CSS zone 3a to the area of the concave portion is 1: 2, that is, the convex portion is formed. Since it is necessary to set the area / area of the concave portion to 1/2,
At this time, the flying height of the head slider 6 is 40 nm.

Since it is desired that the spacing between the magnetic disk 3 and the magnetic head 8 is 50 nm or less, in order to set the flying height of the head slider 6 to 50 nm, the data zone 3b of the magnetic disk 3 must be provided. It is necessary to set the ratio of the area of the convex portion formed to the area of the concave portion to be 2: 1, that is, the area of the convex portion / the area of the concave portion = 2. Therefore, the head slider 6 moves from the CSS zone 3a to the data zone 3b.
In order to eliminate the change in the attitude of the head slider 6 when the head slider 6 moves to the position, the convex portion formed in the CSS zone 3a, that is, the pit 3
The height of p needs to be 10 nm higher than the height of the protrusion formed in the data zone 3b, that is, the height of the data track 3d. For example, when the height of the data track 3d formed in the data zone 3b is 200 nm, the CSS zone 3
The height of the pit 3p formed at a is 210 nm.

As described above, the ratio of the area of the convex portion to the area of the concave portion formed in the region corresponding to the CSS zone 3a in the stamper for producing such a magnetic disk 3 is 2: 1, that is, the ratio of the convex portion Area / area of recess = 2, and the ratio of the area of the projection to the area of the recess formed in the region corresponding to the data zone 3b is 1: 2, ie, the area of the projection / area of the recess = 1/2. Become. The height of the pit 3p formed in the area corresponding to the CSS zone 3a is equal to the height of the data track 3d formed in the area corresponding to the data zone 3b.
10 nm higher than the height of

FIG. 6 shows a stamper forming process for forming the magnetic disk substrate of the magnetic disk 3 described above.
This will be described with reference to FIGS. First, a resist 21 is applied to the surface of a disk-shaped glass master 20 by spin coating or the like.
Coat uniformly with a thickness of 00 nm. This glass master 20
Is mirror-finished, the surface of the applied resist 21 also becomes a mirror surface reflecting the surface properties of the glass master 20 (FIG. 6A).

After applying the resist 21, the resist 21
In the area corresponding to the data zone 3b of the magnetic disk 3 on the surface of the magnetic disk 3, the data track 3t and the guard band 3
A pattern of concave and convex as g is drawn using the laser oscillator 22. At this time, if the resist 21 is a positive type resist, the portion irradiated with the laser beam L flows down upon development, so that the portion serving as the data track 3t is not irradiated with the laser beam L, and the portion of the guard band 3g is not irradiated. The pattern is drawn by irradiating the laser beam L on the
(B)).

Data track 3t and guard band 3g
After drawing a pattern of concavities and convexities, the resist 21 is developed. As a result, the resist 21 at a portion where the laser beam L has not been irradiated remains (FIG. 6C). Resist 21
After the development, Ni (nickel) is electrolessly plated on the surface of the glass master 20 (FIG. 7D). Further, Ni is electrolytically plated on the surface of the electroless plating layer 23 (FIG. 7E). As a result, the surface of the glass master 20 becomes Ni
Is deposited to form a stamper composed of the electroless plating layer 23 and the electrolytic plating layer 24.

Here, the reasons for performing the electroless plating and the electrolytic plating are as follows. Electroless plating has a low deposition rate, but since no bubbles are generated in the plating bath during the plating step, a plating layer having no defects can be formed. On the other hand, in the electrolytic plating, although the deposition rate is high, bubbles are generated in the plating bath during the plating process, so that the bubbles may be involved in the plating layer and defects may occur. Therefore, first, in order to improve the surface transferability when used as a stamper, the electroless plating layer 23 having no defect even if the man-hour is taken is formed, and then the electroless plating layer 23 when used as a stamper is formed. In order to have a thickness that can withstand the molding pressure, the electrolytic plating layer 24 is formed without any man-hour even if there is a defect. Then, the electroless plating layer 23 and the electrolytic plating layer 24 are separated from the glass master 20 to form a stamper 25 (FIG. 7).
(F)).

Next, a resist 21 is formed on the surface of the stamper 25.
a is uniformly applied to a thickness of 500 nm by spin coating or the like (FIG. 8G). Here, the reason why the thickness of the resist 21a is set to 500 nm is that the speed at which the resist 21a is etched and the speed at which the electroless plating layer 23 are etched differ depending on the accelerating voltage. Since the etching speed is higher, it is determined in consideration of the 210 nm etching of the electroless plating layer 23 and other margins.

After the application of the resist 21a, the resist 2
CSS zone 3a of the magnetic disk 3 on the surface 1a
Are drawn using the laser oscillator 22 in the area corresponding to the pattern (3). At this time, if the resist 21a is a positive type resist, the portion irradiated with the laser beam L flows down upon development, so that the portion that becomes the pit 3p is irradiated with the laser beam L, and the portion other than the pit 3p is irradiated with the laser beam L. A pattern is drawn without irradiating L (FIG. 8 (H)). After drawing a pattern of concavities and convexities to become the pits 3p, the resist 21a is developed. This allows
The resist 21a at the portion where the laser beam L has not been irradiated remains (FIG. 8 (I)).

After developing the resist 21a, the exposed electroless plating layer 23 is removed by a physical ion etching apparatus.
Etch 0 nm (FIG. 8 (J)). At this time, the remaining resist 21a is also slightly etched. This physical ion etching apparatus is an apparatus that causes ions accelerated by a voltage to collide with an object to be etched and processes the object to be etched with the collision energy. Therefore, a predetermined processing amount can be obtained by selecting an appropriate acceleration voltage and ion irradiation time. In addition, it can be similarly performed by chemical etching in addition to physical ion etching.
Then, after etching the electroless plating layer 23 (FIG. 9)
(K)), the remaining resist 21a is peeled off with a solvent such as acetone to obtain a final stamper 25a (FIG. 9).
(L)).

FIG. 1 shows an injection molding process of a magnetic disk substrate using the stamper 25a thus produced.
This will be described with reference to FIG. Here, the shape of the magnetic disk substrate is, for example, an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 1.
It has a 2 mm disk shape. As a resin material of the magnetic disk substrate, for example, APO (Amorphus Poly)
(Orefin) -based resin. Further, the injection molding machine includes a fixed mold 26 and a movable mold 27, for example, as shown in FIG. On one end face of the fixed mold 26, a cavity 28 to which a stamper 25a is attached and which is filled with resin is provided. Further, it penetrates from the other end surface of the fixed mold 26 to the center of the cavity 28, and
A gate is provided for guiding the resin into the inside. The movable mold 27 is provided with a cutter 29 for cutting a portion to be a center hole of the magnetic disk substrate.

First, the stamper 2 is placed on the wall of the cavity 28.
5a is attached, and the movable mold 27 is moved to close the cavity 28 (FIG. 11A). Then, the resin 30 is filled into the cavity 28 through the gate (FIG. 11).
(B)). After the resin 30 is filled, the cutter 29 is projected into the cavity 28 to cut the inner diameter of the resin 30 (FIG. 11C). Next, the resin 30 is cooled and solidified (FIG. 11D), the cutter 29 is returned into the movable mold 27, and the movable mold 27 is moved to open the cavity 28 (FIG. 11E). Finally, the magnetic disk substrate 31 and the sprue (portion of the inner diameter of the resin 30 cut by the cutter 29) are taken out of the cavity 28, the magnetic disk substrate 31 is transported to the next step, and the sprue is discarded (FIG. 11 (F)).

The magnetic disk substrate 31 formed as described above reflects the surface shape of the stamper 25a as shown in FIG. That is, CSS zone 3a
, That is, the height (210 nm) of the pits 3p can be formed higher than the height surface of the data zone 3b, ie, the height (200 nm) of the data track 3t.

In this example, the stamper 25a is attached only to the fixed mold 26, but the process for injection molding by attaching it to the movable mold 27 is basically the same as the above process. In this embodiment, the magnetic disk substrate is formed by injection molding a resin. However, a moldable material, for example, glass or a soft metal may be stamped and formed into a magnetic disk substrate.

[0036]

As described above, according to the present invention, it is possible to have an appropriate head slider contact area and to reduce the change in the attitude of the head slider when moving from the contact area to the information recording area. Becomes

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration example of a hard disk drive which is an embodiment of a magnetic disk drive of the present invention.

FIG. 2 is a plan view showing an embodiment of a magnetic disk according to the present invention.

FIG. 3 is an exemplary perspective view showing details of a magnetic disk shown in FIG. 2;

FIG. 4 is a sectional side view showing details of the magnetic disk shown in FIG. 2;

FIG. 5 is a diagram showing a relationship between a flying height of a head slider and an area ratio of unevenness of a magnetic disk.

FIG. 6 is a first view showing a step of forming a stamper for forming a magnetic disk substrate according to an embodiment of the magnetic disk of the present invention.

FIG. 7 is a second view showing a step of forming a stamper for forming a magnetic disk substrate according to the embodiment of the magnetic disk of the present invention;

FIG. 8 is a third view showing a step of forming a stamper for forming a magnetic disk substrate according to the embodiment of the magnetic disk of the present invention;

FIG. 9 is a fourth diagram showing a step of forming a stamper for forming a magnetic disk substrate according to the embodiment of the magnetic disk of the present invention.

FIG. 10 is a cross-sectional side view showing an example of a molded portion for producing an embodiment of the magnetic disk of the present invention.

FIG. 11 is a cross-sectional side view showing a molding process for producing an embodiment of the magnetic disk of the present invention.

FIG. 12 is a cross-sectional side view showing an embodiment of a magnetic disk formed by a stamper for producing a magnetic disk substrate according to the embodiment of the magnetic disk of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hard disk device, 2 ... Housing, 3 ...
Magnetic disk, 3a CSS zone, 3b data zone, 3p pit, 3t data track, 3g guard band, 4 arm, 4a
... Pivot, 5 ... Voice coil, 6 ... Head slider, 7 ... Voice coil motor, 7a, 7b
... magnet, 8 ... magnetic head, 9 ... motor, 10a ... upper cover dimple, 11 ... arm dimple, 12 ... elastic body, 20 ... glass master,
21, 21a: resist, 22: laser oscillator, 23: electroless plating layer, 24: electrolytic plating layer, 25, 25a: stamper, 26: fixed mold, 27 ..Movable molds, 28 ... cavities, 29
... Cutter, 30 ... Resin, 31 ... Magnetic disk substrate

Claims (6)

[Claims] 1. A magnetic disk having a concave and convex portion for recording information on a surface thereof, and a convex pit row for contacting a head slider on an inner peripheral portion or an outer peripheral portion thereof, 2. The magnetic disk according to claim 1, wherein the height of the concave and convex portions is different from the height of the pit row. 2. The magnetic disk according to claim 1, wherein the height of the uneven portion is lower than the height of the pit row. 3. The magnetic disk according to claim 1, wherein the ratio of the area of the projection to the area of the recess in the information recording area is different from the area of the area of the projection to the area of the recess in the contact area. 4. The magnetic disk according to claim 1, wherein the ratio of the area of the projection to the area of the recess in the information recording area is larger than the ratio of the area of the projection to the area of the recess in the contact area. 5. A magnetic head device having a head slider on which a magnetic head for recording / reproducing information is mounted, and a concave / convex portion for recording the information formed on a surface, and the head is provided on an inner or outer peripheral portion thereof. A magnetic disk device, comprising: a pit row having a convex shape for contacting a slider; and a magnetic disk having a height of the concave and convex portions and a height of the pit row different from each other. 6. An uneven portion for recording information is formed on the surface, and a convex pit row for contacting a head slider is formed on an inner peripheral portion or an outer peripheral portion thereof. When forming a stamper for forming a magnetic disk substrate of a magnetic disk in which the heights of the pit rows are different from each other, an uneven portion for forming the uneven portion is formed on a surface portion, and the entire surface is formed. Removing the covering material which is covered with a covering material and covering the surface portion where the concave portion for forming the pit row is formed; removing the covering material for the concave portion for forming the pit row; Forming a stamper for forming a substrate for a magnetic disk, wherein the stamper is formed on the surface portion and the remaining covering material is removed to form a stamper.