JP2730318B2 - Manufacturing method of glass magnetic disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a glass magnetic disk using glass as a substrate and having a low coefficient of friction and high CSS (contact start / stop) durability.

[0002]

2. Description of the Related Art In recent years, glass has attracted attention as a substrate of a magnetic disk. Since the glass substrate is excellent in flatness, low flying of the head is possible, and as a result, high density can be achieved. However, if the flatness is excellent, the head will be attracted to the disk. Therefore, in order to prevent this, and to realize a low friction coefficient and high CSS durability, the surface of the disk must be formed appropriately rough.

Conventionally, as a magnetic disk of this type, as shown in Japanese Patent Application Laid-Open No. 62-26623, the surface of a glass substrate is treated with a hydrofluoric acid aqueous solution, There are known a chemical corrosion method by immersion in an aqueous solution or the like, and a method of processing by a chemical polishing method using a combination of the chemical corrosion method and the mechanical polishing method. Further, as a similar magnetic disk, as disclosed in Japanese Patent Application Laid-Open No. 63-160010, a method is known in which a glass substrate is rubbed with a tape or the like to which abrasive grains are attached by a mechanical method. . Further, as described in Japanese Patent Application Laid-Open No. 2-9016, a method is known in which after a non-magnetic metal film is formed on a glass substrate, the surface thereof is polished concentrically in the circumferential direction by machining. Have been.

[0004]

However, in the above-mentioned conventional magnetic disk, the head is roughened by processing the surface of the glass substrate so that the head is not attracted to the surface of the disk. In addition, there is a problem that it is difficult to control the surface roughness of the glass substrate and mass productivity is deteriorated.

Accordingly, it is an object of the present invention to provide a method of manufacturing a glass magnetic disk capable of forming a rough surface so that a head does not stick to the surface with an inexpensive configuration and manufacturing method.

[0006]

According to the present invention, in order to achieve the above object, in manufacturing a magnetic disk on a glass substrate, the gas pressure of argon is 25 to 60 mTorr and the thickness of the layer is reduced on the glass substrate. 0.5 to 0.75 μm
A step of forming a layer for adjusting the surface roughness of the disk by sputtering so that a non-magnetic underlayer is formed on the layer for adjusting the surface roughness, The magnetic layer is formed on the underlayer.

[0007]

Since the present invention has the above-mentioned structure, the surface roughness is adjusted two-dimensionally by appropriately adjusting the thickness and the surface roughness of the layer for adjusting the surface roughness of the disk. The head can be formed with a rough surface so that the head is not attracted to the surface by an inexpensive configuration and manufacturing method.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing one embodiment of a glass magnetic disk according to the present invention, FIG. 2 is a graph showing the relationship between the thickness and gas pressure of the surface roughness adjusting layer of FIG. 1 and the surface roughness,
FIG. 3 is a graph showing the relationship between the film thickness of the surface roughness adjusting layer and the substrate temperature and the surface roughness of FIG. 1, and FIG. 4 is a graph showing the relationship between the film thickness of the surface roughness adjusting layer and the dynamic friction coefficient of FIG. Graph showing, FIG.
Is a graph showing the relationship between the film thickness of the surface roughness adjusting layer of FIG. 1 and the surface roughness of the disk, and FIGS. 6 to 8 are the relationships between the CSS cycle and the change of the dynamic friction coefficient of three examples of the disk of this embodiment, respectively. FIG.

In FIG. 1, the glass magnetic disk of this embodiment has a surface roughness adjusting layer 2, a non-magnetic underlayer 3, a magnetic layer 4, a protective layer 5, and a lubricant layer 6 sequentially laminated on a glass substrate 1. It has been formed. The surface roughness adjusting layer 2 and the nonmagnetic underlayer 3 are formed of, for example, chromium (Cr), and the magnetic layer 4
Is formed of, for example, CoCrTa, the protective layer 5 is formed of, for example, carbon (C), and the lubricant layer 6 is, for example, Fomblin AM2001 manufactured by Montezison.

[0010] As shown in FIG.
Argon (Ar) gas pressure 25, 45, 60 mTorr
r, the chromium film thickness is 0.1, 0.3, 0.
When formed by DC magnetron sputtering so as to have a thickness of 5, 0.6, 0.75, 0.9, and 1.0 μm, the surface roughness of the surface roughness adjusting layer 2 (the average roughness of the center line).
Ra became extremely large when formed to a film thickness of 0.5 μm or more, and became larger as the gas pressure of argon (Ar) was higher.

As shown in FIG. 3, argon (A)
r) The gas pressure was fixed at 60 mTorr and the temperature of the glass substrate 1 was not heated, and the chromium film thickness was formed at 250 ° C. so as to be 0.5, 0.75 and 1.0 μm, respectively. , The surface roughness Ra of the surface roughness adjustment layer 2
Increased when the temperature of the glass substrate 1 was 250 ° C. Therefore, the surface roughness Ra of the surface roughness adjusting layer 2
It was found that chromium was used as the surface roughness adjusting layer 2, and that the larger the gas pressure of argon (Ar) and the higher the temperature of the glass substrate 1, the larger the surface roughness.

When a chromium nonmagnetic underlayer 3 is also laminated on the surface roughness adjusting layer 2, the nonmagnetic underlayer 3 is formed of argon (A) in order to distinguish it from the surface roughness adjusting layer 2.
It is desirable to form the film by lowering the gas pressure of r). Then, as shown in FIG. 4, the gas pressure is 25 mTorr.
(△ mark), 60 mTorr (印 mark) and a film thickness of 0.
A magnetic disk is formed by sequentially laminating a nonmagnetic underlayer 3, a magnetic layer 4, and a protective layer 5 on a surface roughness adjusting layer 2 having a thickness of 3, 0.5, and 0.7 μm, and a dynamic friction coefficient of the surface of the protective layer 5 is formed. Was measured, the dynamic friction coefficient was 0.3 or less when the thickness of the surface roughness adjusting layer 2 was 0.5 μm or more.

Further, when a magnetic disk laminated with the lubricant layer 6 added thereto was formed and the kinetic friction coefficient of the surface was measured, a large difference was found in the kinetic friction coefficient as shown by a black circle and a black triangle in FIG. Did not occur. The dynamic friction coefficient of the disk surface when the surface roughness adjusting layer 2 is not interposed is 1.0.
When the flying height of the head is 0.075 μm, the head does not contact the disk.

When the surface roughness Ra of the disk on which the layers 1 to 6 were laminated was measured, as shown in FIG. 5, as the thickness of the surface roughness adjusting layer 2 increased, the surface roughness Ra of the disk increased. Ra was greatly measured. The surface roughness Ra of the disk is considerably larger than the surface roughness Ra of the surface roughness adjusting layer 2 shown in FIG. 3, but the surface roughness Ra of the surface roughness adjusting layer 2 is smaller than the surface roughness Ra of the disk. The significant effect is apparent from FIG.

Here, the surface roughness Ra of the surface roughness adjusting layer 2
In order to form the layers 3 and 4 having good magnetic properties on the surface roughness adjusting layer 2, it is desirable that the thickness be appropriately small. That is, the surface roughness Ra of the disk increases as the film thickness of the surface roughness adjustment layer 2 increases, but considering the low flying height of the head on the disk, the film thickness and surface roughness of the surface roughness adjustment layer 2 are considered. It is desirable that the degree Ra is appropriately small.

FIGS. 6 to 8 show the surface roughness adjusting layer 2 respectively.
Are 0.3, 0.5, 0.75 μm, the gas pressure during film formation is 60, 60, 25 mTorr, the temperature of the glass substrate 1 is 250 ° C., and the surface roughness Ra of the disk is 6.8. ,
17.2 and 18.8 Angstrom Discs AC
2 shows the relationship between the CSS cycle and the dynamic friction coefficient change.

As shown in FIG. 6, a disk A having a surface roughness adjusting layer 2 having a thickness of 0.3 μm and a disk surface roughness Ra of 6.8 Å has a large dynamic friction coefficient as the CSS cycle increases. As shown in FIGS. 7 and 8, the surface roughness adjusting layer 2 has a thickness of 0.5, 0.7
5 μm, disk surface roughness Ra 17.2, 18.8
The dynamic friction coefficients of Angstroms disks B and C hardly changed.

Therefore, according to the above embodiment, chromium is effective as the surface roughness adjusting layer 2, and as shown in FIG.
75 μm is effective, and the surface roughness Ra of the disc is 1
5 to 25 angstroms is effective.

Japanese Patent Application Laid-Open No. 62-293511 discloses that Ti, Zr, Hf, V,
At least one of Nb, Ta, Cr, Mo, W, and Mn
Interposing an intermediate layer made of a metal oxide containing a kind of element,
It is known that a contact start stop (CSS) characteristic is improved by preventing peeling of a substrate and a metal base layer. However, in this conventional example, an intermediate layer of Cr oxide or the like is interposed to prevent separation of the substrate and the metal underlayer, so that the surface roughness of the disk does not become rough, and the head is adsorbed on the surface of the disk. In this embodiment, since the surface roughness adjusting layer 2 is formed so that the surface roughness of the disk becomes rough, there is an effect that the head does not stick to the surface of the disk.

[0020]

As is apparent from the above description, according to the present invention, the film is formed by appropriately adjusting the thickness and the surface roughness of the layer for adjusting the surface roughness of the disk. In addition, the surface roughness is two-dimensionally isotropic, and the surface can be formed coarsely with an inexpensive configuration and manufacturing method so that the head does not stick to the surface.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a glass magnetic disk according to the present invention.

FIG. 2 is a graph showing the relationship between the thickness and the gas pressure of the surface roughness adjusting layer of FIG. 1 and the surface roughness.

FIG. 3 is a graph showing the relationship between the film thickness of the surface roughness adjusting layer of FIG. 1, the substrate temperature, and the surface roughness.

FIG. 4 is a graph showing the relationship between the film thickness of the surface roughness adjusting layer of FIG. 1 and the dynamic friction coefficient.

5 is a graph showing the relationship between the thickness of the surface roughness adjusting layer of FIG. 1 and the surface roughness of the disk.

FIG. 6 is a graph showing a relationship between a CSS cycle and a change in dynamic friction coefficient of the disk of the embodiment.

FIG. 7 is a graph showing a relationship between a CSS cycle and a change in dynamic friction coefficient of the disk of the present embodiment.

FIG. 8 is a graph showing a relationship between a CSS cycle of the disk of the present embodiment and a change in dynamic friction coefficient.

[Explanation of symbols]

 1 glass substrate 2 surface roughness adjusting layer 3 non-magnetic underlayer

Claims (2)

(57) [Claims] 1. A method of manufacturing a glass magnetic disk comprising a magnetic disk on a glass substrate, wherein a gas pressure of argon is 25 to 60 mTorr and a thickness of a layer is 0.5 to 0. Forming a layer for adjusting the surface roughness of the disk by sputtering so as to have a thickness of 75 μm; forming a non-magnetic underlayer on the layer for adjusting the surface roughness; Forming a magnetic layer on the magnetic underlayer. 2. The method of manufacturing a glass magnetic disk according to claim 1, wherein a layer for adjusting the surface roughness is provided so that the center line average roughness of the surface of the glass magnetic disk is 15 to 25 Å.