JP2514074B2 - Magnetic recording media - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording medium having excellent surface properties and magnetic recording / reproducing characteristics.

(Prior Art) Conventionally, as a thin film type magnetic recording medium having a high recording density,
NiP electroless plating is applied to the surface of non-magnetic materials such as glass and aluminum, and Co- is applied to the surface of the base formed by texturing in the circumferential direction.
A magnetic disk provided with a magnetic layer (magnetic thin film) of a ferromagnetic metal material such as Ni alloy is generally known.

In such a magnetic recording medium, the magnetic recording medium has magnetic anisotropy in the circumferential direction, and in the magnetic recording medium circumferentially oriented in this way, the orientation direction and the relative traveling direction of the magnetic head coincide with each other. Therefore, it is generally known that the recording and reproducing characteristics are advantageous.

(Problems to be solved by the invention) By the way, in the conventional texturing process for a magnetic disk, a groove-like scratch (scratch scratch) is formed on the surface of a substrate by using an abrasive containing fine coating particles having a particle size of about 1 μm to 2 μm. It was done by attaching.

However, when the texturing process is performed using such an abrasive, burrs 2 are formed at both ends of the groove 1 as shown in FIG. 3, and a protrusion 3 due to uncut portions is inevitably formed.

Here, the flying height of a magnetic head in a recent hard disk drive device is becoming smaller and smaller as the recording density of the device is increased.

When the flying height of the magnetic head is reduced in this way, the burr 2 and the protrusion 3 as described above become a major cause of head crash and the like.

Further, the groove 1 formed by the texturing process using the conventional abrasive may be cut in the middle, or the grooves may cross each other in the middle to form a regular concentric pattern. It has been found that the magnetic recording / reproducing characteristics are adversely affected.

(Means for Solving the Problems) The present invention has been made in view of the above situation, and an object thereof is to provide a magnetic recording medium having excellent surface properties and magnetic recording / reproducing characteristics.

In order to achieve this object, the present invention provides a magnetic recording medium comprising a magnetic layer formed of a magnetic material on the surface of a substrate formed of a non-magnetic material, wherein the surface of the substrate is dry-etched. The present invention provides a magnetic recording medium characterized in that a plurality of concentric circular grooves are formed at a predetermined fine pitch by the method, and the magnetic layer is formed on the surface of the concentric circular grooves.

(Examples) Hereinafter, preferred examples of the magnetic recording medium according to the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of the magnetic disk according to the present embodiment. This magnetic disk has a nonmagnetic chromium layer 6a formed on the surface of a base 5 made of a nonmagnetic material. A plurality of grooves 7 having a predetermined width and depth are concentrically formed with a predetermined fine pitch, another chromium layer 6b is formed again on the surface of this chromium layer 6a, and then a ferromagnetic metal thin film material is formed on the surface. The magnetic layer 8 and the protective film 9 made of carbon are sequentially formed.

Examples of the substrate 5 include well-known materials such as non-magnetic metal materials such as aluminum, ceramic materials such as glass and porcelain, and polymer materials such as polyvinyl chloride, cellulose acetate, polyethylene, polypropylene, polycarbonate, polyimide and polyamide. It is possible to use the disk formed in.

The ferromagnetic metal thin film material forming the magnetic layer 8 is, for example, one or more alloys of cobalt, nickel, iron, or these metals and tantalum, titanium, manganese,
An alloy with chromium, phosphorus, yttrium, samarium, bismuth, or the like can be used, and the magnetic layer 8 can be formed by a known method such as a sputtering method, a vapor deposition method, an ion plating method, or a plating method.

 Hereinafter, the present invention will be described with reference to specific examples.

(Example) This magnetic disk has a width on the surface of a non-magnetic chromium layer 6 formed on the surface of a disk-shaped substrate 5 made of glass.
A plurality of grooves 7 having a thickness of 0.5 μm and an additional thickness of 0.05 μm are concentrically formed at a pitch of 1 μm, and a magnetic layer 8 made of CoCrTa alloy and a protective film 9 made of carbon are sequentially formed on the surface of the grooves 7. .

To make this magnetic disk, first, as shown in FIG. 2 (A), a chromium layer 6a is formed on the surface of the substrate 5.
A film is formed with a thickness of 0.2 μm.

Next, as shown in FIG. 2B, a resist film 10 is applied to the surface of the chrome layer 6a, and laser light is radiated from the surface of the resist film 10 to develop the resist film 10. 2C, a plurality of concentric patterns each having a width of 0.5 μm for forming the groove 7 are formed at a pitch of 1 μm as shown in FIG. 2 (C).

After that, the groove 7 is formed by dry etching so that the depth becomes 0.05 μm as shown in FIG.
Further, the remaining resist film 10 is removed as shown in FIG.

As a result, the surface of the base 5 has a width of 0.5 μm and a depth of 0.05.
A plurality of μm grooves 7 are formed concentrically at a pitch of 1 μm.

Then, as shown in FIG. 2 (F), another chromium layer 6b is again formed on the surface of the substrate 5 having the groove 7 thus formed by 0.05 μm.
formed to a thickness of m, and further, as shown in FIG.
The magnetic layer 8 made of CrTa alloy is formed to a thickness of 0.06 μm by the sputtering method, and the protective film 9 is formed on the surface of the magnetic layer 8 by the sputtering method as shown in FIG. 0.04
It is formed to a thickness of μm.

(Comparative Example) After the NiP electroless plating is applied to the surface of the aluminum substrate that has been generally known to have been conventionally textured, the magnetic layer made of CoCrTa alloy and the carbon layer made of carbon are formed on the surface. A magnetic disk having a protective film sequentially formed by a sputtering method was manufactured.

For each of the above magnetic disks, the coercive force Hc, the squareness ratio Rs, and the coercive force squareness ratio S were measured as the magnetostatic characteristics and are shown in Table 1.

In addition, for each of the above magnetic disks, the number of protrusions of 0.18 μm or more, which is substantially equal to the flying height of the magnetic head, is counted and shown in Table 2.

As is clear from Table 1 above, the magnetic disk of the example has a larger squareness ratio Rs and the squareness ratio S of the coercive force than the magnetic disk of the comparative example, and the magnetostatic characteristics are improved. are doing.

Further, as is clear from Table 2 above, the magnetic disk of the example has a significantly smaller number of protrusions that cause a head crash or the like than the magnetic disk of the comparative example.

Therefore, as is clear from these results, the magnetic disk of the present example has improved surface properties and magnetostatic characteristics as compared with the magnetic disk of the comparative example, and therefore the magnetic recording / reproducing characteristics can be improved.

By the way, in the above-mentioned embodiment, the chromium layer 6 was formed to form the groove 7 on the surface of the substrate 5, and the groove 7 was formed through this chromium layer 6. However, the groove 7 is directly formed on the surface of the substrate 5.
Of course, it may be formed.

Further, as a result of experiments, it was found that if the width of the groove 7 is 5 μm or less, the same effect as that of the above-mentioned embodiment is obtained, and if it is more than 5 μm, the magnetic head attracting phenomenon occurs, which is not preferable.

Further, the depth of the groove 7 is preferably 0.03 μm or more,
It was found that when the thickness was less than that, the unevenness due to the grooves disappeared due to the magnetic layer 8 and the protective film 9.

(Effect of the invention) As is apparent from the above description, according to the present invention, by forming a plurality of grooves on the surface of the substrate by a dry etching method, by forming a magnetic layer on the surface of the plurality of grooves A plurality of regular concentric grooves can be formed at a fine pitch, and burrs and uncut portions unlike the conventional texturing process hardly occur.

Further, since the magnetic layer is formed after the groove is formed by the dry etching method, burrs are not generated and the magnetic characteristics are not deteriorated.

As a result, according to the present invention, the surface properties and magnetic recording / reproducing characteristics of this type of magnetic recording medium can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetic recording medium according to the present invention, FIGS. 2A to 2H are process drawings showing a method of manufacturing a magnetic disk according to this embodiment, and FIG. FIG. 3 is an enlarged cross-sectional view of a main part of a base of the magnetic recording medium of FIG. 5 ... Base, 7 ... Groove, 8 ... Magnetic layer.

Claims (1)

(57) [Claims] 1. A magnetic recording medium in which a magnetic layer is formed of a magnetic material on the surface of a substrate formed of a non-magnetic material, and a plurality of concentric circles are formed on the surface of the substrate by a dry etching method. A magnetic recording medium characterized in that grooves are formed at a predetermined minute pitch, and the magnetic layer is formed on the surfaces of the plurality of concentric grooves.