JPH06150300A - Magnetic recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium which has a high CSS (contact start-stop) characteristic, highly stable durability, and excellent electromagnetic conversion characteristic and can be improved in high density recording and over-write characteristic. CONSTITUTION:This recording medium is constituted by successively forming a base metallic layer 2, magnetic layer 3, and protective layer 4 on a nonmagnetic substrate 1. The layer 4 is formed in such a way that the inner peripheral side of the layer 4 with which a magnetic head comes into contact is formed in a thick film area 4a and the part of the layer 4 on the outside of the area 4a corresponding to the data recording area of the magnetic layer 3 is formed in a thin film area 4b. Therefore, an excellent abrasion resistance and high CSS characteristic can be obtained from the thick film area 4a and a high electromagnetic conversion characteristic can be obtained from the thin film area 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a magnetic recording medium such as a magnetic disk, and more particularly to a protective layer formed to protect the magnetic layer of the magnetic recording medium.

[0002]

2. Description of the Related Art In recent years, fixed magnetic disk devices have been widely used as external recording devices for information processing devices such as computers. FIG. 3 shows the configuration of a general magnetic recording medium used in this fixed magnetic disk device.
In this magnetic recording medium, a nonmagnetic metal layer 12 is formed on a nonmagnetic substrate 11 to form a nonmagnetic substrate 1, and a nonmagnetic metal underlayer 2 is laminated on the substrate 1. Then, on the metal underlayer 2, a ferromagnetic alloy body of Co—Cr—
Ta (Cobalt / Chromium / Tantalum) or Co-C
The magnetic layer 3 is laminated in a thin film form of r-Pt (cobalt, chromium, platinum) or the like, and the protective layer 4 made of amorphous carbon or the like is further formed on the magnetic layer 3. Then, a lubricating layer 5 made of a liquid lubricant is provided on the protective layer 4 as needed to form a magnetic recording medium (magnetic disk).

The non-magnetic substrate 1 is, for example, Al.
-N is formed on the non-magnetic substrate 11 of Mg alloy by electroless plating.
Formed i-P plating layer 12, alumite base,
Glass substrates and ceramic substrates are used. Then, the base 1 may be polished as necessary to form irregularities by a texture or the like. While heating the non-magnetic substrate 1 to ˜200 ° C., the non-magnetic metal underlayer 2 made of Cr and Co by sputtering in an Ar atmosphere.
A magnetic layer 3 made of —Cr—Ta or the like and a protective layer 4 made of amorphous carbon are sequentially formed by sputtering. Then, the protective layer 4 is coated with a fluorocarbon liquid lubricant to form the lubricating layer 5.

When the magnetic disk having such a structure is mounted on a hard disk device (fixed magnetic disk device) or the like, the surface of the magnetic disk is repeatedly brought into contact with the magnetic head of the device. This is because, in a hard disk drive, etc., the magnetic head is generally in contact with the surface of the magnetic disk that is stopped when the device is stopped, and when the recording / reproduction is performed from this state, the magnetic head is not This is because a CSS (contact start / stop) method is adopted in which the information is read or written by flying slightly above the surface of the magnetic disk that rotates at a high speed and traveling low. In the CSS method, a head touch with high energy is momentarily generated between the magnetic head and the magnetic disk surface as the power is turned on and off and the seek operation of the magnetic head is performed. Therefore, the magnetic disk needs to have a sufficient sliding property such as lubricity or abrasion resistance and endure the contact with the magnetic head. For this reason, the protective layer 4 is formed on the surface of the magnetic layer 3. , And the lubricating layer 5 is formed as necessary.

[0005]

As described above, the CS
In a magnetic disk to which the S method is applied, C that shows the difficulty of head crash due to repeated CSS
High SS characteristics are required, and sliding characteristics between the disk surface and the magnetic head are important. In order to improve this sliding property, it is effective to reduce the friction coefficient between the magnetic disk surface and the magnetic head. If the substrate 1 is textured to increase the surface roughness, the magnetic disk surface and magnetic Since the coefficient of friction with the head is reduced, it is possible to prevent the magnetic head from adsorbing and the like and improve the sliding characteristics. Further, in order to improve the strength of the protective layer 4 and increase the abrasion resistance, it is conceivable to increase the thickness of the protective layer 4, or to form the protective layer 4 having a compositionally high hardness.

However, improving the sliding characteristics of the magnetic disk hinders the improvement of the electromagnetic conversion characteristics thereof, and the recording density is increased with the increase in the amount of information in recent years, and good overwrite characteristics and reproduction are achieved. There is a problem that output etc. cannot be obtained. That is, in order to improve the electromagnetic conversion characteristics, it is necessary to shorten the distance between the magnetic layer 3 and the magnetic head, but in order to improve the sliding characteristics, unevenness such as texture is introduced to roughen the surface of the magnetic disk. When the height is increased, it is necessary to secure a large flying distance of the magnetic head in order to prevent head crash. The hardness of the protective layer 4 made of amorphous carbon is Al ₂ which is the slider material of the magnetic head.
Since the hardness is lower than that of O ₃ TiC or CaTiO ₃ ,
It is easy to cause abrasion, and it is difficult to thin the protective layer 4.

In view of the above problems, the object of the present invention is to
It is an object of the present invention to provide a magnetic recording medium having high CSS characteristics, stable in durability, excellent in electromagnetic conversion characteristics, capable of achieving high recording density and improvement of overwrite characteristics.

[0008]

In order to solve the above problems, in a magnetic recording medium according to the present invention, that is, a magnetic recording medium having at least a protective layer for protecting a magnetic layer laminated on a non-magnetic substrate. Are characterized in that the protective layer has a thick film region and a thin film region. In this magnetic recording medium, it is preferable that the thick film region is formed on the inner peripheral side of the substrate and the thin film region is formed on the outer peripheral side of the thick film region.

In such a magnetic recording medium, a magnetic recording medium having a protective layer forming step of forming a protective layer by depositing a protective film on the surface of a magnetic layer laminated on a non-magnetic substrate by sputtering is manufactured. In the method, in the step of forming the protective layer, a mask provided on a predetermined region of the magnetic layer is used to temporarily suppress the deposition of the protective film on this region, and the thick film region relative to the protective layer is formed. It can be manufactured by including a protective film deposition suppressing means for forming a thin film region and a thin film region.

[0010]

In general, in a hard disk drive adopting the CSS system, the magnetic head is fixed near the center hole on the inner peripheral side of the magnetic disk (magnetic recording medium) when the apparatus is stopped, and the magnetic head and the surface of the magnetic disk are fixed. It can be said that the contact area of is fixed. Therefore, in the magnetic recording medium according to the present invention, a region where the surface of the magnetic recording medium contacts the magnetic head, that is, a protective layer region on the inner peripheral side of the substrate is formed as a thick film region and is formed on the outer peripheral side of this thick film region. By forming the protective layer as a thin film region, the portion in contact with the magnetic head has a sufficient film thickness with excellent abrasion resistance, and a track is formed, and data reading / writing is actually performed. The protective layer formed on the data recording area of the magnetic layer can be thinned to shorten the distance between the magnetic layer and the magnetic head. As described above, according to the present invention, while maintaining high CSS characteristics with excellent wear resistance,
It is possible to shorten the distance between the magnetic layer and the magnetic head to improve the electromagnetic conversion characteristics, and to obtain a magnetic recording medium having a high recording density and excellent reproduction output and overwrite characteristics.

The protective layer having such a thick film region and a thin film region has a preset predetermined thickness of the magnetic layer in the protective layer forming step of depositing the protective film on the surface side of the magnetic layer to form the protective layer. By using a mask provided on the region to temporarily suppress the deposition of the protective film on this region and adopting a protective film deposition suppressing means for forming a thick film region and a thin film region relative to the protective layer. , Can be easily created in the same process.

[0012]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1A is a plan view showing the structure of a magnetic disk (magnetic recording medium) according to an embodiment of the present invention, FIG.
(B) is the AA 'cross section figure. Note that FIG. 1 (b)
3, the same parts as those of the conventional magnetic disk shown in FIG. 3 are designated by the same reference numerals. In the figure, in the magnetic disk of this example, a Ni-P electroless plating 12 is applied on an Al alloy substrate 11 to form a substrate 1. The base body 1 is textured and further subjected to precision cleaning. Then, a Cr layer having a thickness of about 1000 Å is used to form a base metal layer 2 and a thickness of Co-Cr-Ta of 80.
A 0Å magnetic layer 3 and a protective layer 4 made of carbon are formed. Here, the point to be noted in the magnetic disk of this example is that the thickness of the protective layer 4 is not uniform and the thickness is 300 Å
Is formed having a thick film region 4a and a thin film region 4b having a film thickness of 100Å. Thick film region 4 of protective layer 4
a is formed in a circular shape on the innermost circumference side of the disk-shaped magnetic disk, while the thin film region 4b is formed on the outer circumference side of the thick film region 4a and corresponds to the data recording region of the magnetic layer 3. ing. The boundary between the thick film region 4a and the thin film region 4b has a gentle slope to prevent damage due to head touch. In addition, 20 is a center hall.

Such a protective layer 4 is formed on the surface of the magnetic layer 3 by sputtering using carbon as a target. In the protective layer forming step, first, the thin film region 4b corresponding to the data recording region of the magnetic layer 3 is formed. A mask that suppresses the deposition of the carbon thin film is placed on the formation region and the thick film region 4 is formed.
A predetermined film thickness (about 200Å) is obtained on the formation region of a. At this time, almost no carbon thin film is deposited in the formation region of the thin film region 4b. After removing the mask on the formation region of the thin film region 4b, the carbon thin film is substantially uniformly deposited on the surface of the magnetic layer 3 by performing the subsequent sputtering, so that the thick film region 4a having a film thickness of 300Å, The protective layer 4 having the thin film region 4b having a film thickness of 100Å can be obtained. Since the mask used in this protective layer forming step is a mechanically driven shutter provided in the film forming chamber, the protective layer 4 can be formed while the disc is installed in the film forming chamber. it can.

FIG. 2 shows the CS with the change in the film thickness of the protective layer 4.
The transition of the S characteristic and the overwrite characteristic is shown.
In FIG. 2, the line (a) shows the transition of the CSS characteristics, and the line (b) shows the transition of the overwrite characteristics. As is clear from the figure, the CSS characteristics due to the abrasion of the protective layer 4 improve as the thickness of the protective layer 4 increases. On the other hand, since the overwrite characteristic is determined by the distance between the magnetic layer 3 and the magnetic head, the thinner the protective layer 4 is, the better the characteristic is. This overwrite characteristic is one of the electromagnetic conversion characteristics that determines the reproduction output, resolution, and recording density of the magnetic disk, and the protective layer 4 is thin and the distance between the magnetic layer 3 and the magnetic head is shortened. The magnetic disk tends to have good reproduction output, resolution, and recording density.

In the magnetic disk having the above structure, the inner peripheral side of the surface of the magnetic disk which the magnetic head contacts when the apparatus is stopped is formed as the thick film region 4a of the protective layer 4.
A thin film region 4b is formed on the data recording region of the magnetic layer 3 on the outer peripheral side of the thick film region 4a. Here, the film thickness of the thick film region 4a is 300Å, which shows high CSS characteristics in FIG. Further, the film thickness of the thin film region 4b is 100Å, which shows a good overwrite characteristic (electromagnetic conversion characteristic) in FIG. As described above, in the magnetic disk of this example, since the thickness of the protective layer 4 in the contact area with the magnetic head is sufficient, head crush is less likely to occur, CSS characteristics are excellent, and data recording of the magnetic layer 3 is performed. Since the protective layer 4 on the area is thin and the distance between the magnetic layer 3 and the magnetic head can be shortened, the electromagnetic conversion characteristics of the magnetic disk can be improved. Therefore, according to the present invention, it is possible to construct a magnetic disk that is excellent in both CSS characteristics and electromagnetic conversion characteristics, which have conventionally been in a trade-off relationship, and have good reproduction output and overwrite characteristics at high recording density. In addition, it is possible to provide a permanently stable magnetic disk.

[0017]

As described above, the magnetic recording medium according to the present invention is characterized in that the protective layer has the thick film region and the thin film region. Therefore, according to the present invention, a portion where the magnetic head comes into contact with the surface of the magnetic recording medium when the apparatus is stopped is made to be a thick film area to have sufficient strength for abrasion resistance and to correspond to the data recording area of the magnetic layer. Since it is possible to shorten the distance between the magnetic layer and the magnetic head by using the portion as a thin film region, it is possible to realize a magnetic recording medium that satisfies both the CSS characteristic and the electromagnetic conversion characteristic, which are conventionally in a trade-off relationship. Therefore, it is possible to obtain a magnetic recording medium having a high recording density and stable performance such as reproduction output, resolution and overwrite characteristics.

[Brief description of drawings]

FIG. 1A is a plan view showing a configuration of a magnetic disk (magnetic recording medium) according to an embodiment of the present invention, and FIG. 1B is a sectional view showing a state in which it is cut along the line AA ′. Is.

FIG. 2 is a graph showing changes in CSS characteristics and overwrite characteristics with changes in the thickness of a protective layer.

FIG. 3 is an explanatory diagram showing a configuration of a general magnetic disk (magnetic recording medium).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Metal underlayer 3 ... Magnetic layer 4 ... Protective layer 4a ... Thick film area 4b ... Thin film area 5 ... Lubrication layer 11 ... Non-magnetic substrate 12 ... Non-magnetic metal layer 20 ... Center hole

Claims (3)

[Claims] 1. A magnetic recording medium having at least a protective layer for protecting a magnetic layer laminated on a non-magnetic substrate, wherein the protective layer has a thick film region and a thin film region. Magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the thick film region is formed on an inner peripheral side of the substrate, and the thin film region is formed on an outer peripheral side of the thick film region. 3. A method of manufacturing a magnetic recording medium, comprising a protective layer forming step of forming a protective layer by depositing a protective film on a surface of a magnetic layer laminated on a non-magnetic substrate by sputtering. The forming step temporarily suppresses the deposition of the protective film on a predetermined region of the magnetic layer, which is set on a predetermined region of the magnetic layer, and a thick film region and a thin film relative to the protective layer. A method of manufacturing a magnetic recording medium, comprising: a protective film deposition suppressing means for forming a region.