JPH0845215A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To eliminate a difference in level of a magnetic recording medium produced by forming a ground surface layer, magnetic layer and protective layer on a substrate formed with the difference in level by texturing and to prevent flawing and head clash by contact of the medium with a head. CONSTITUTION:The surface of the magnetic recording medium 10 is made flush by controlling film thicknesses in such a manner that the films are formed thicker in the low step part 2a of the difference in level than in the high step part 2B at the time of forming the films. Since the magnetic recording medium is formable to the flush surface without having the difference in level, the generation of the flaws and the head clash by the contact with the magnetic head are eliminated. The surface condition of the substrate by the texturing is sufficiently maintained without being impaired by the adjustment of the film thickness of the film forming layers and, therefore, the magnetic recording medium which has the smooth surface in data regions and excellent magnetic characteristics and has excellent floating characteristics without having a problem of sticking to the head in the CSS region is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having excellent flying characteristics, which has improved surface characteristics by eliminating steps formed on a substrate. is there.

[0002]

2. Description of the Related Art In recent years, with the development of information processing technology for computers and the like, magnetic recording media such as magnetic disks have come to be widely used as external storage devices.

Conventionally, as a magnetic recording medium, an aluminum alloy substrate is subjected to an alumite treatment or a non-magnetic plating treatment such as Ni-P plating, followed by coating an underlayer such as Cr, and then a magnetic thin film layer of a Co-based alloy. What is coated and then coated with a carbonaceous protective film is used.

In such a magnetic recording medium, in recent years,
With the increase in density of magnetic recording media (magnetic disks), the distance between the magnetic disk and the magnetic head, that is, the flying height is becoming smaller and smaller, and recently, the flying height is about 0.15 μm or less. When the flying height of the magnetic head is remarkably reduced in this way, if there is a protrusion on the surface of the magnetic disk, the protrusion and the magnetic head come into contact with each other to cause a head crash and damage the surface of the magnetic disk. Further, even a minute protrusion that does not lead to a head crash is likely to cause various errors when reading and writing information due to contact with the magnetic head.

On the other hand, with respect to the magnetic disk, miniaturization is in progress in parallel with the increase in capacity and density, and the motor for spindle rotation and the like are becoming smaller and smaller. For this reason, the torque of the motor is insufficient, and the phenomenon that the magnetic head does not fly while being fixed to the magnetic disk surface is likely to occur. As a means for preventing the sticking of the magnetic head by reducing the contact between the magnetic head and the surface of the magnetic disk, conventionally, a surface processing treatment for forming fine grooves on the substrate surface of the magnetic disk (referred to as "texture processing"). ) Or etching treatment is performed. In particular, in order to reduce the flying height, the texturing of the data area (area in which the information signal is recorded) is finished as smooth as possible, while the CSS (contact with the magnetic head) area does not stick to the head. , CSS is used for texture processing so that scratches do not occur.

[0006]

However, in the above-mentioned texture processing, different surface processing conditions are formed by adopting different texture processing conditions for the data area and the CSS area of the magnetic disk substrate. Therefore, the data area and C
At the boundary with the SS region, a step is generated in the radial direction.

As described above, the magnetic disk having a step in the radial direction of the surface is rotated to move the magnetic head to the CSS.
From the data area to the CSS when moving from the area to the data area and conversely when stopping the rotation of the magnetic disk.
When the head is moved to the area, the magnetic head comes into contact with a step portion in the radial direction on the surface of the magnetic disk, which causes a problem such as a scratch, a pull, and a head crash.

The present invention solves the above-mentioned problems of the prior art and provides a magnetic recording medium in which a magnetic disk having a textured surface on a substrate eliminates a step in the radial direction of the surface and which has excellent magnetic head flying characteristics. The purpose is to do.

[0009]

A magnetic recording medium of the present invention has a disk-shaped substrate and a film-forming layer including an underlayer, a magnetic layer and a protective layer formed on the plate surface of the substrate. In the magnetic recording medium in which the CSS region of the plate surface of the substrate is a recess that is recessed more than the data region, the thickness of the film formation layer in the CSS region is smaller than the thickness of the film formation layer in the data region. Is also made larger so that the surface of the film formation layer is flush with the CSS region to the data region.

That is, the inventors of the present invention have made diligent studies to solve the above-mentioned inconvenience caused by the texture processing of the substrate surface, and as a result, after performing the texture processing on the substrate, the film formation is performed in the next film forming step. By controlling the film thickness of the layer, the step in the radial direction generated by the texture processing is eliminated, and the surface of the magnetic recording medium is made flush so that scratches and head crashes caused by contact with the magnetic head are eliminated. The inventors have found that they can be achieved and have completed the present invention.

The present invention will be described below in detail with reference to the drawings.

FIG. 1 is an enlarged cross-sectional view of the CSS area and its vicinity of a magnetic disk 10 according to an embodiment of the magnetic recording medium of the present invention.

As the substrate 1 of the magnetic recording medium in the present invention, a disc-shaped (disc-shaped) substrate made of an aluminum alloy is generally used. Usually, as shown in FIG. 1, the aluminum alloy substrate 1 has a predetermined thickness. After processing, the surface is mirror-finished, and then a nonmagnetic metal such as Ni-P alloy or Ni-Cu-P alloy is formed on the surface of the substrate by electroless plating to a film thickness of about 5 to 20 μm. The substrate surface layer 2 is formed by filming.

Next, the substrate 1 having the substrate surface layer 2 formed thereon is subjected to a texture processing. In the present invention, preferably, the specific unevenness and the striation pattern are formed by the following two-step texture processing.

First, in the first step, the average surface roughness (Ra) on the entire surface of the substrate is 10 to 80Å, preferably 15 to 10.
The texture is processed so that it becomes 40Å. Then the second
As a process, only the CSS region of the substrate 1 that has undergone the first process is subjected to texture processing to finish to Ra 40 to 100Å, preferably 50 to 80Å.

The first step of this texture processing is to perform slurry grinding of the substrate surface layer 2 of the substrate 1 under a specific condition using a polishing tape and free abrasive grains, or tape polishing using only a polishing tape. Can be implemented in.
In the second step of the texture processing, a polishing tape and specific loose abrasive grains are used, or only the polishing tape is used, and only the CSS region of the substrate surface that has undergone the first step is ground under specific conditions. , Ra to prevent sticking to the magnetic head and to prevent head crush, and to further remove burrs on the substrate surface and protrusions such as burrs.

Since the texturing is performed at a higher level, it is possible to perform multi-step texturing such as three steps or four steps, if necessary. More preferably, after the above-mentioned texture processing, etching treatment is performed to effectively remove the protrusions, burrs and the like remaining on the substrate surface after the texture processing, and to make the substrate surface have a smooth surface condition, and thus the levitation characteristics and CSS. The characteristics can be greatly improved.

By such two-step texture processing, the CSS region of the substrate surface layer 2 of the substrate 1 is recessed more than the data region, and the CSS region becomes the low step portion 2A and the data region becomes the high step portion 2B. The step S is formed at the boundary between the CSS area and the data area. Normally, the size of the step S is about 100 to 2000Å.

On the surface of the substrate 1 that has been subjected to texture processing or further etching processing, next, as a base layer 3,
Normally, chromium (Cr) is sputtered to produce Cr.
The base layer 3 is formed. The thickness of the Cr underlayer 3 is usually in the range of 50 to 2000Å.

Next, the magnetic layer 4 is formed on the Cr underlayer 3 of the substrate 1. As the magnetic layer 4, Co-Cr,
Co-Ni, Co-Cr-X, Co-Ni-
A thin film layer of a Co-based alloy represented by X, Co-W-X or the like is suitable. Here, X is Li, Si, C
a, Ti, V, Cr, Ni, As, Y, Zr, Nb, M
o, Ru, Rh, Ag, Sb, Hf, Ta, W, Re,
Os, Ir, Pt, Au, La, Ce, Pr, Nd, P
Examples include one or more elements selected from the group consisting of m, Sm, and Eu.

The magnetic layer 4 made of such a Co alloy
Is usually deposited on the underlayer 3 of the substrate 1 by means such as sputtering, and its film thickness is usually 200 to
The range is 2500Å.

The protective layer formed on the magnetic layer 4 is preferably a carbonaceous film, and the carbon protective layer 5 is usually
Diamond-like in a rare gas atmosphere such as argon or He,
It is deposited on the magnetic layer 4 by sputtering using graphite-like or amorphous-like carbon as a target. The thickness of the protective layer 5 is usually 100 to 20.
The range is 00Å.

In this embodiment, the protective layer 5 as described above is used.
The formation of the protective layer 5 is performed in two steps as shown in I or II below, and the thickness of the protective layer 5 is changed between the CSS area and the data area, that is, the CSS area. By making the thickness of the protective layer 5 in the data region thicker than the thickness of the protective layer 5 in the data region, the step S of the surface layer 2 of the substrate 1 formed by the texture processing is eliminated,
The magnetic disk 10 has a flat surface.

I As shown in FIG. 1, first, a carbon base layer 5A having a predetermined thickness, for example, 100 to 2000 Å is formed on the magnetic layer 4 of the substrate 1 by sputtering over the entire surface.
Then, having an opening only in a portion corresponding to the CSS area,
Sputtering is performed using a mask plate covering a portion corresponding to the data area, and the thickness is 100 to 2 so that the surface is flush with the surface of the carbon base layer 5A in the data area.
A carbon adjusting layer 5B for eliminating a step difference of about 000Å is formed in the CSS region, and the carbon base layer 5A and the carbon adjusting layer 5B form a carbon protective layer 5. This allows
A carbon protective layer 5 having a flush surface is formed.

II First, sputtering is performed using a mask plate having an opening only in a portion corresponding to the CSS region and covering a portion corresponding to the data region, and the surface thereof is the surface of the magnetic layer 4 of the substrate 1 in the data region. A carbon adjustment layer having a thickness of about 100 to 2000 Å is formed on the magnetic layer 4 in the CSS region of the substrate 1 so as to be flush with the above. Next, a carbon surface layer having a predetermined thickness, for example, 100 to
Form to about 2000Å. Also by this method, as a result, the carbon protective layer 5 whose surface is flush with the carbon adjusting layer and the carbon surface layer is formed as in FIG.

The thus-obtained magnetic disk 10 having a flush surface is used by coating the protective layer 5 with a lubricant 6.

In the present invention, the surface of the film formation layer is controlled by controlling the film thickness so that the film formation layer in the CSS region is thicker than the film formation layer in the data region. As long as it is made flush from the region to the data region, the film forming layer for controlling the film thickness is not limited to the carbon protective layer described above, but the film of the chromium underlayer or the magnetic layer. The surface may be made flush by adjusting the thickness. Furthermore, when forming a film forming layer other than the underlayer, the magnetic layer, and the protective layer, for example, a buffer layer, the film thickness of this layer can be adjusted.

[0028]

According to the present invention, the step on the surface of the substrate formed by the texture processing can be easily eliminated by adjusting the film thickness of the film forming layer formed on the substrate, and the surface of the magnetic recording medium can be substantially removed. Since it can be made flush with each other and has no step, the occurrence of scratches and head crash due to contact of the magnetic head is eliminated. Moreover, since the surface condition of the substrate due to the texturing is sufficiently maintained without being damaged by the film thickness adjustment of the film forming layer, the surface is smooth in the data area and the magnetic characteristics are excellent. It is possible to provide a magnetic recording medium which is free from the problem of sticking and is excellent in flying characteristics.

[0029]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 A magnetic disk 10 shown in FIG. 1 was manufactured.

That is, first, Ni-is formed by electroless plating.
The surface of the aluminum alloy disc-shaped substrate 1 on which the P-plated substrate surface layer 2 is applied with a thickness of about 15 μm is polished to a surface having an average surface roughness (Ra) of about 20Å, and then a polishing tape is applied to the entire surface of the substrate. A fine groove is formed by the used texture processing, and further, the texture processing using loose abrasive grains is performed to obtain a surface average roughness (Ra) of about 35.
The surface condition was about Å and maximum protrusion height (Rp) was about 130Å. After that, only the CSS region was subjected to the same treatment as described above to finish the surface state of Ra about 65Å and Rp 270Å.

On the surface of the substrate 1 thus textured, a Cr underlayer (thickness 1000Å) 3 and a magnetic layer (thickness 500Å) made of a Co--Cr--Ta alloy were formed by sputtering according to a conventional method. After sequentially forming 4, the carbon base layer 5A was formed to a thickness of 400 Å. After that, a mask plate having an opening is attached only to a portion corresponding to the CSS region, and a carbon adjusting layer 5B is further formed only on the CSS region with a thickness of 1000 Å to form a carbon protective layer 5 by sputtering, and a lubricant 6 is further applied. Then, as shown in FIG. 1, a magnetic disk 10 having a flush surface was manufactured.

The glide floating characteristics and surface condition of the obtained disk were evaluated by the following methods, and the results are shown in Table 1 and FIG.
It was shown to.

Glide levitation characteristics The collision between the head and the protrusion of the disk was detected by the PZT element using RG550 manufactured by Hitachi DECO, and evaluated as the flying height of the external head.

Observation of surface state (average surface roughness (R
a), maximum protrusion height (Rp)) A surface roughness meter (“ET-30HK” manufactured by Kosaka Laboratory) with a 0.5 μm conical tip has a measuring length of 250 μm.
It was measured in m. As a measuring method, the surface on an arbitrary straight line on the circumference of the substrate was measured in the radial direction, and the surface average roughness (Ra) and the maximum protrusion height (Rp) were obtained.

Comparative Example 1 In the same manner as in Example 1, except that a carbon adjustment layer having a thickness of 1000 Å was not formed in the CSS region, and a carbon base layer having a thickness of 300 Å was formed, and then a lubricant was applied on the carbon base layer. To manufacture the magnetic disk 10A shown in FIG.
The same evaluation was performed and the results are shown in Table 1 and FIG.
2, members having the same functions as those in FIG. 1 are designated by the same reference numerals.

[0037]

[Table 1]

From Table 1 and FIG. 3, according to the present invention, the glide is eliminated by eliminating the step difference on the surface of the magnetic disk for each of the data area and the CSS area without deteriorating the preferable surface state by the texture processing. It is clear that the characteristics can be improved significantly.

In FIG. 3, the values of Example 1 indicated by ▲ and the values of Comparative Example 1 indicated by □ are glide characteristics obtained over the entire surfaces of the magnetic disks obtained in Example 1 and Comparative Example 1, respectively. The CSS area indicated by ∇ and the data area indicated by ∘ are the results of glide characteristics obtained only for the CSS area and the data area of the magnetic disk of the first embodiment, respectively.

[0040]

As described in detail above, according to the magnetic recording medium of the present invention, the data area on the substrate surface is made a smooth surface by the texture processing, and the CSS area is provided with the magnetic head and the magnetic recording medium. In a magnetic recording medium that has a surface roughness that does not stick to it, eliminate the step created by texture processing by controlling the film thickness of the film formation layer on the substrate, and make the surface a flush structure. Thus, when the magnetic recording medium is started or stopped, scratches and head crashes are prevented from occurring at the boundary between the CSS area and the data area due to contact with the magnetic head, and the surface characteristics and the flying characteristics of the magnetic recording medium are prevented. Can be significantly improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of a magnetic recording medium of the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing a conventional magnetic recording medium.

FIG. 3 is a graph showing the measurement results of glide characteristics in Example 1 and Comparative Example 1.

[Explanation of symbols]

 1 Substrate 2 Substrate Surface Layer 2A Low Step 2B High Step 3 Underlayer 4 Magnetic Layer 5 Carbon Protective Layer 5A Carbon Base Layer 5B Carbon Adjustment Layer 6 Lubricant 10 Magnetic Disk S Step

Claims (1)

[Claims] 1. A disk-shaped substrate, and a film-forming layer formed on the plate surface of the substrate, the underlayer, a magnetic layer, and a protective layer, the CSS region of the plate surface of the substrate. In the magnetic recording medium having a recessed portion which is recessed from the data area, the surface of the film-formed layer is increased by making the thickness of the film-formed layer in the CSS area larger than the thickness of the film-formed layer in the data area. A magnetic recording medium having a flat surface from the CSS area to the data area.