JP2625652B2 - Memory device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a memory device using a magnetic recording medium, and more particularly to a memory device using a magnetic recording medium having a silicon dioxide thin film and a lubricating layer on a recording magnetic layer.

[0002]

2. Description of the Related Art In recent years, with the development of information processing technology, the amount of information carried by memory devices has increased dramatically, and there has been an increasing demand for large-capacity magnetic recording media such as floppy disks and hard disks. To meet this demand, research and development of magnetic recording media capable of high-density recording have been actively conducted. In particular, for a coating type magnetic recording medium generally used at present, Co-Cr is used as a recording magnetic layer.
Metal thin-film magnetic recording media formed by sputtering or vapor-depositing a metal magnetic thin film such as described above are promising as media suitable for high-density recording.

In the case of a coating type medium, a recording magnetic layer is formed by mixing a magnetic powder with a binder or the like and coating the mixture on a substrate. Therefore, it is easy to mix a lubricant into the magnetic layer. Lubricity between the medium and the magnetic head can be maintained, and sufficient durability of the medium and the head can be obtained.

On the other hand, since it is difficult to mix a lubricant into a recording magnetic layer in a metal thin film medium, when a magnetic head made of a hard material such as ferrite runs over the medium, the medium solidifies and the surface of the head is hardened. Damages such as scratches are more likely to occur. In this case, not only the durability of the medium and the head is impaired, but also the distance between the medium and the head is increased due to the adhesion of wear powder on the medium and the head, and the spacing and the spacing are increased.
The loss increases, and the recording / reproducing frequency characteristics deteriorate significantly.

Therefore, in the case of a metal thin film medium, it is conceivable to apply a lubricant on the recording magnetic layer. However, since the film formed by sputtering or the like has a very good surface property, the lubricant is wet. Therefore, it is difficult to apply the lubricant with sufficient adhesion and evenly thereon, and the above-mentioned problem still remains.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to enable a lubricating layer to be formed uniformly with a sufficient adhesive force even when a recording magnetic layer is formed of a metal thin film. Can significantly increase the durability of
An object of the present invention is to provide a memory device using a magnetic recording medium having good recording and reproduction characteristics.

[0007]

To achieve the above object, according to the solution to ## in this onset bright, it is silicon dioxide thin film is formed on the recording magnetic layer, and the composition formula of the silicon dioxide film was SiO _2-X
X is selected in the range of 0 <X <0.5,
A magnetic recording medium lubricant layer on the silicon dioxide thin film is formed, when recording and reproducing information on the magnetic recording medium
In both, it provides a memory device comprising a kite and a <br/> magnetic head that travels in contact over the magnetic recording medium.

[0008]

It is well known to form a silicon dioxide thin film on a recording magnetic layer of a magnetic recording medium used in a memory device, and it is also known to form a lubricating layer. Is in an oxygen-deficient state to facilitate the application of the lubricating layer. The silicon dioxide thin film having such oxygen deficiency can be easily formed by a method such as sputtering in an oxygen-deficient atmosphere.

Since the lubricating layer is formed via the silicon dioxide thin film in which oxygen deficiency has occurred, a magnetic recording medium having a good and uniform lubricating layer can be provided. This is because, when oxygen deficiency occurs in the silicon dioxide thin film, an arc-shaped electron pair is generated in the silicon atom, which is activated as compared with the silicon dioxide thin film having no oxygen deficiency. This is because the bonding force is strengthened.

Here, the degree of oxygen deficiency in the silicon dioxide thin film is expressed by the following formula when the composition formula of the silicon dioxide thin film is SiO ₂ -X.
Is preferably in the range of 0 <X <0.5. When the silicon dioxide thin film is made to be in an oxygen deficient state so that X falls within this range, the bonding force with the lubricating layer can be very effectively increased while the degree of the silicon dioxide thin film itself is sufficiently maintained.

[0011]

FIG. 1 is a sectional view showing a magnetic recording medium used in a memory device according to an embodiment of the present invention. In the drawing, a substrate 1 is a resin-made film-shaped substrate, and a 0.5 μm-thick Co—Cr alloy thin film 2 is formed as a recording magnetic layer on the substrate 1 by, for example, DC magnetron sputtering. In the case of a perpendicular magnetic recording medium, the Co—Cr alloy thin film 2 is oriented so as to have an easy axis of magnetization in a direction perpendicular to the film surface. A silicon dioxide thin film 3 having a thickness of about 200 Å is formed on the Co—Cr alloy thin film 2, and a liquid lubricating layer 4 is applied and formed on the silicon dioxide thin film 3.

The silicon dioxide thin film 3 is formed by, for example, high frequency sputtering using a silicon dioxide target. In this case, the vacuum chamber for sputtering is previously set to 10 ⁻⁷ Torr.
After evacuating to a vacuum and removing the impurity gas sufficiently, oxygen gas is introduced in a smaller amount than in the case of forming normal silicon dioxide (SiO ₂ ), that is, up to 10 ⁻⁷ to 10 ⁻³ Torr, and then argon gas is introduced. Introduce the total pressure to 10 ^-2 To
This was performed at about rr. The silicon dioxide thin film 3 thus formed is in an oxygen deficient state, and its composition formula is S
iO _2-X . In this case, the value of X can be arbitrarily controlled within a range larger than 0 by the oxygen partial pressure of the sputtering atmosphere and the thin film speed. The value of X is measured, for example, on a (100) Si wafer by using S
It can be performed by forming iO _2-X and performing analysis by RBS (Rutherford back scattering). Since the silicon dioxide thin film 3 thus formed is activated due to the state of oxygen deficiency, when the liquid lubricant is applied thereon to form the lubrication layer 4, it is necessary to uniformly apply the lubricant with good wettability. Can be. Further, the bonding force between the silicon dioxide thin film 3 and the lubricating layer 4 is also increased. Therefore, it can greatly contribute to the improvement of the durability of the magnetic recording medium and the magnetic head.

Table 1 shows the experimental results of examining the change in durability when the value of X is changed depending on the oxygen partial pressure ratio in the sputtering atmosphere and the film forming rate. However, in the experiment, the magnetic recording medium with the above configuration was created in the form of a floppy disk,
While rotating this disc at 300 revolutions per minute,
The test was performed by bringing a ferrite magnetic head into contact with the same track on the disk. Here, the durability is the medium (disk)
And the number of passes (pass) until at least one of the heads is significantly damaged. In the case of a medium, significant damage refers to a state where at least a part of the silicon dioxide thin film 3 and the Co—Cr alloy thin film 2 is displaced, and the surface of the base 1 is exposed.

[0014]

[Table 1] From the above results, it can be seen that when the value of X is larger than zero, that is, when the number of oxygen atoms constituting the silicon dioxide thin film 3 is less than twice the number of silicon atoms, the durability is significantly improved. Particularly, it is preferable that the value of X is in the range of 0.1 <X <0.3. When the value of X is in this range, the durability is improved to 3,000,000 passes or more, which is one digit or more as compared with the case where X is zero. At the maximum, a value exceeding 3,000,000 passes can be obtained. The required degree of durability varies depending on the application and the like, but if the number of passes is 500,000 or more, the memory device can be almost practically used. Therefore, it is particularly desirable that the value of X be in the range of 0.1 <X <0.3 described above.

When the value of X exceeds 0.5, the durability decreases from the peak because the adhesion of the lubricating layer 4 is improved in the oxygen-deficient state, but the hardness of the silicon dioxide thin film 3 itself decreases. Because it goes. However, the reason why the durability is lower than when X is zero is that the value of X is very large, for example, close to 2, as inferred from the above experimental results, and the silicon dioxide thin film 3 Since it loses its properties and becomes closer to silicon, in that state the name itself of the silicon dioxide thin film no longer holds.

As described above, according to the present invention, when the composition formula of the silicon dioxide thin film is SiO _{2 -X} , X is 0 <X <
By selecting an oxygen deficiency state in the range of 0.5, the adhesion of the lubricating layer formed thereon can be increased, and the durability of the magnetic recording medium itself and the magnetic head can be significantly increased. In addition, the uniform formation of the lubricating layer reduces the reduction and fluctuation of the signal reproduction output, thereby reducing the error rate. Such an effect is not limited to the above-described floppy disk, but can be applied to a memory device using another magnetic recording medium such as a hard disk.

FIG. 2 shows a magnetic recording medium used in a memory device according to another embodiment of the present invention.
A Cr alloy thin film 12 is formed, a silicon dioxide thin film 13 is formed thereon by, for example, magnetron sputtering, and a solid lubricating layer 14 is further formed thereon by sputtering. Since the silicon dioxide thin film 13 is formed by sputtering in an argon atmosphere having an oxygen partial pressure of about 10% of the argon partial pressure, the silicon dioxide thin film 13 is also in an oxygen deficient state. In the magnetic recording medium thus formed, excellent durability can be obtained as in the magnetic recording medium described in the above embodiment.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist thereof. For example, as the recording magnetic layer, Co
Although a -Cr alloy thin film has been exemplified, a Co-Cr-Ni alloy thin film may be used. In particular, the present invention is effective for a magnetic recording medium in which a metal thin film on which a lubricating layer must be formed on the surface is used as a recording magnetic layer. Further, various materials for the base and the lubricating layer can be selected. Further, the present invention can be applied not only to a perpendicular magnetic recording medium but also to a longitudinal magnetic recording medium.

[0019]

As described above, according to the present invention, C
Even in a magnetic recording medium using a metal thin film such as an o-Cr alloy thin film as a recording magnetic layer, the lubrication between the medium and the magnetic head is sufficiently performed.
Damage is significantly reduced and durability is greatly improved.

When a liquid lubricant is applied as the lubricating layer, for example, the lubricant can be applied to a uniform thickness with good wettability between the silicon dioxide thin film and the lubricant, so that the spacing loss is reduced. As a result, output reduction and output fluctuation during signal reproduction are reduced, and the error rate is also reduced. Therefore,
Recording and reproduction characteristics are improved.

Further, since the silicon dioxide thin film is harder than a magnetic metal thin film such as a Co—Cr alloy film forming a recording magnetic layer, the medium surface is mechanically protected to prevent scratches and the like from entering. However, it goes without saying that shielding the recording magnetic layer from the outside air has the effect of improving the corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a sectional view of a magnetic recording medium according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin film-like base | substrate 2 Co-Cr alloy thin film (recording magnetic layer) 3 Silicon dioxide thin film 4 Liquid lubrication layer 11 Non-magnetic base 12 Co-Cr alloy thin film (recording magnetic layer) 13 Silicon dioxide thin film 14 Solid lubrication layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masayuki Sunai 1 Toshiba, Komukai Toshiba-cho, Saisaki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Research Institute, Inc. (56) References JP-A-58-220244 (JP, A) JP-A-52-127203 (JP, A) JP-A-58-185029 (JP, A) JP-B-6-12568 (JP, B2)

Claims (3)

(57) [Claims] 1. A thin film of silicon dioxide is formed on the recording magnetic layer, and the composition formula of the silicon dioxide film was SiO _2-X
X is selected in the range of 0 <X <0.5,
A magnetic recording medium lubricant layer on the silicon dioxide thin film is formed, when recording and reproducing information on the magnetic recording medium
In both, the memory device comprising a kite and a <br/> magnetic head that travels in contact over the magnetic recording medium. 2. The memory device according to claim 1, wherein said recording magnetic layer is a metal thin film. 3. The metal thin film forming the recording magnetic layer,
3. The memory device according to claim 2, wherein the memory device is a Co-Cr alloy.