JPH04106722A - Magnetic disk - Google Patents

Abstract

PURPOSE:To obtain a surface protective film structure with high hardness and abrasion resistance, having superior in adhesion with a substrate and also good lubricating alility by forming a meta silicified film, a metal oxide film or a metal nitride film on the lower surface of a hard amorphous carbon film. CONSTITUTION:The silicified, oxide or nitride film 14 is provided over approximately the whole surface on a magnetic recording medium 13 of the substrate 12, and on that the hard amorphous carbon film 15 containing hydrogen is further provided, and the protective film is composed of the film 14 and the film 15. To put it concretely, a magnetic disk substrate 25 provided with the film 14 in an RF magnetron spatter method is installed in a vacuum vessel 21, and then a mixed gas is introduced from a methane cylinder 28 and a hydrogen cylinder 29 to form the film 15. At this time, a vacuum degree is specifed as a range of 0.1 - 10 Torr, and a mixing ratio of methane 28 and hydrogen 29 as 0.01 - 0.10, and then a voltage value under regular glow discharge but just prior to generating abnormal glow discharge. By this method, the protective film having a film thickness required for high hardness and superior abrasion resistance and also high density magnetic recording is thus obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a two-magnetic disc with high hardness and low wear. This relates to a magnetic tape that has excellent resistance to wear and slippage, and has a protective film structure on its surface.

[Prior Art] Magnetic disks and magnetic heads are widely used as magnetic disk devices in computer terminal information storage devices.

A magnetic disk is made of ferrite, iron, Kobal 1 to 1,000,000 on a substrate such as an aluminum metal substrate or a plastic substrate. Nickel or a compound thereof, or a rare earth metal such as neodymium, samarium, gadolinium, or terbium, or a compound made of these metals is used as a magnetic recording medium by depositing it in a thin film by the Yasbatta coating method.

There are various types of magnetic heads, and they extract the magnetic flux from the magnetism embedded in the recording medium as a signal, and are used as close to the magnetic disk surface as possible.

As described above, the magnetic head and the magnetic disk are likely to collide and rub against each other, and a protective film is required to protect the recording medium from scratches and the like that occur on the recording medium of the magnetic disk.

The important points that a protective film should have are that it should have good V corrosion resistance, good adhesion to the substrate, and good surface lubrication. The hardness of the film can be used to evaluate wear resistance, and the higher the hardness, the better the wear resistance. Adhesion is important so that the protective film does not peel off when the magnetic head contacts or rubs. Since adhesion depends on the surface properties of the magnetic disk medium, it is necessary to use a protective film material that matches the properties of the medium.

Conventionally, for this purpose, silicon dioxide (Si02), silicon nitride (Si3N4>, alumina (
Oxides and nitrides such as 203), or carbon films are used. S13\4, SiO2 and Af!
203 is usually prepared by dissolving one part of an organometallic compound of silicon or aluminum in a solvent, and then coating it and drying it! ! ! It is produced by a processing method, a sputtering method in nitrogen or a mixed gas of argon and oxygen, or a vapor deposition method.

The carbon film can be produced by a carbon ion beam evaporation method made by discharging a carbon electrode as described in Japanese Patent Application Laid-Open No. 52-90281, or by a carbon ion beam evaporation method made by discharging a carbon electrode as described in Japanese Patent Application Laid-Open No. 52-90281,
Journal of Noncrystalline Solites
of non-crystalline 5olid
s) Vol. 35, l> and Vol. 36, No. 435 (made by methods such as carbon evaporation deposition as described herein).

An example of providing a coating mainly composed of carbon on the surface of a magnetic disk is, for example, as seen in Japanese Patent Application No. 58140/1983, a film mainly composed of carbon is provided on the part where there is no magnetic recording medium. There is also a structure in which the film is thicker in the area where collision friction with the magnetic head is likely to occur, and the film is thinner in the recording area.

At this time, it was necessary to place the film with a brightness of 500 to 10008 in the recording area and a brightness of 1000 to 10000 in the area where the magnetic head would stop.

In recent years, highly developed technology (1 = information processing technology) is increasingly demanding information α (+1) for human appearance, and along with this, high-density magnetic recording media technology is occupying an important position. For this reason, the protective film on the surface of the magnetic disk is required to be even thinner, and a thickness of about 100 to 50 people is also required.

[Problem to be solved by the invention: However, various conventional protective film materials do not have sufficient hardness, adhesion, wear resistance, or corrosion resistance. Kg y't
rtm2, 3000 Kg'#2 for alumina or 30 for I=silicon nitride or conventional sputtering method, etc.
It was about 00 Kg・'m2. The minimum thickness of the protective film is approximately 5,008 mm, and if the thickness is less than this, the hardness, abrasion resistance, and corrosion resistance will be significantly reduced, resulting in fundamental defects.

In addition, because it is a protective film with such a heavy weight, a patent application filed in 1982
As seen in No. 58140, it is necessary to have a special structure, and there is also the problem of high manufacturing costs due to processing technology, and a protective film with good characteristics has not been realized even at a thickness of 50 Å or less.

As a result of various studies regarding the performance of the protective film, the inventors of the present invention discovered that the apparent hardness and abrasion resistance vary greatly depending on the type of base material to which the protective film is attached. This led to the invention.

That is, the object of the present invention is to provide a magnetic disk having a surface protective film structure with high hardness, excellent wear resistance and adhesion to a substrate, and good lubricity, which improves the various drawbacks mentioned above. It is about providing.

[Means for Solving the Problems] The present invention provides a magnetic disk provided with a hard amorphous carbon film on the surface, in which a metal silicide film is provided on the lower surface of the hard amorphous carbon film.
A magnetic disk characterized in that a metal oxide film or a metal nitride film is formed.

In the present invention, metal silicides include molybdenum silicide, tungsten silicide, titanium silicide, cobalt silicide, zirconium silicide, and vanadium silicide.

It is desirable that the material be at least one selected from niobium silicide and tantalum silicide.

Further, the metal oxide is preferably at least one selected from molybdenum oxide, tungsten oxide, titanium oxide, cobalt oxide, zirconium oxide, vanadium oxide, niobium oxide, and tantalum oxide.

Further, the metal nitride is preferably at least one selected from molybdenum nitride, tungsten nitride, titanium nitride, cobalt nitride, zirconium nitride, vanadium nitride, niobium nitride, and tantalum nitride.

The present invention will be explained below based on the drawings. FIG. 1 is a diagram showing the structure of a magnetic disk according to the present invention.

FIG. 1(a) shows a small plan view of the magnetic disk 11, and the first
Figure Cb) is a cross-sectional view taken along line X-X-1 in Figure 1(a). In Figure 1(b), board 1? A silicide, oxide or nitride film 14 is provided over almost the entire surface of the magnetic recording medium layer 13, and a hard amorphous carbon film 15 containing hydrogen is further provided thereon. It is something that Board 1? As such, it is possible to use an organic film, a metal such as aluminum, or an alloy. In short, the material does not matter as long as it holds the magnetic recording medium layer 13. The thickness of the magnetic recording medium layer 13 is usually 10 pm or less, which is necessary to retain recorded information. Silicide, oxide or nitride film 14 and hard amorphous carbon film 15
The two together constitute a protective film. It goes without saying that it is desirable that the thickness of the protective ff1lli be as thin as possible.

The method of forming the silicide, oxide, or nitride film 14 is not limited to any method that can form a uniform film. Particularly good results were obtained using the steaming method, Yasbatta method, plasma vapor phase chemical deposition method, and sputtering method.

The formation method of hard amorphous carbon rPA15 is methane (CH
4> and hydrogen (H2) mixed residue is effective as a method for synthesizing a good film at low temperature. FIG. 2 is a schematic diagram of an example of a device used by someone.

In FIG. 2, which substrate should be formed with a hard amorphous carbon film serving as a cathode in the vacuum 121? 5 and flat plate electrodes parallel to both sides of the substrate 25. Place 2.

A DC power source 23 is connected to the anode electrode 22 to generate glow discharge between the electrodes.

Specifically, a magnetic disk substrate on which a silicide, oxide, or nitride film is formed using the usual RF magnetron sputtering method. 5 in a vacuum chamber? 1, then introduce the mixed waste from 28 into the methane bomb and the mixed waste from 29 into the hydrogen bomb to form a hard amorphous carbon film (1).The quality of the obtained film depends on the degree of vacuum and the mixing ratio of the waste. Since it varies greatly depending on the voltage applied to the electrodes and the voltage applied to the electrodes, it is necessary to select the optimum value.The degree of vacuum is adjusted from 0.1 Torr to 10 Torr using the exhaust pump ?6 and valve 27.

Methane again? 8 and hydrogen? Mixing ratio of 9 or CH4,・'H
Good results are given when the value is in the range of 2-0, 01 to 0.10. On the other hand, the voltage value (t=) is a normal glow discharge and the conditions immediately before the normal glow discharge occurs give relatively good results.

1 Effect] In the conventional protective film mainly composed of carbon,
As seen in No. 2-58140, it is either used by directly attaching it to the recording medium, or with this formation method, as mentioned earlier, the adhesion is poor and the uniformity of the attached carbon film is not likely to be good. Ta. The cause of this is not clear in detail, but it is thought to be related to the bonding force between the blown film and the recording medium.

In the present invention, some kind of chemical bonding force acts between the magnetic recording medium and the silicide, oxide, or nitride film, or the hard amorphous carbon film and the silicide, oxide, or nitride film, resulting in close contact between the bookmarks. It seems to increase the strength.

Furthermore, the hard amorphous carbon film on the surface contains 20 to 30 at.
The hydrogen in this range compensates for the unsaturated bonds in the carbon film, and the mechanism that increases the hardness of the film itself also works effectively.

Owing to the various features of the present invention described above, it is possible to form a good surface protective film for a magnetic disk even with a thin film, that is, a thickness of 500 Å or less, which was previously impossible.

[Example] Examples of the present invention will be described below.

Example 1 An aluminum alloy with a diameter of 5.25 inches and a thickness of 2M was used as a magnetic disk substrate, and a cobalt-chromium-tantalum compound was deposited on this as a recording medium to a thickness of about 20 m by sputtering. Using.

To form the protective film, first, for molybdenum silicide, tungsten silicide, tantalum silicide, titanium silicide, cobalt silicide, zirconium silicide, vanadium silicide, and niobium silicide, a normal RF magnetron sputtering device is used at a vacuum level of 10-3~] The silicide sintered body was used as a target using argon sputtering in the range of 0-2 TOrr, and the film was formed at a very low temperature with a power of 100-150 W. The thickness of the silicide film was varied from 100 to 1000 This was controlled by varying the sputtering time over a range.

The hard amorphous carbon film was formed using the apparatus shown in FIG.

The DC glow discharge was generated by grounding the substrate 25 side and applying a current of up to several hundred volts at a positive voltage to the electrode 22 facing the substrate 25 from the DC power supply 23. The discharge current density is 01~1 mA, ・'In! n? And so. A mixture of methane and hydrogen is used as a reaction residue at a flow rate of CH4,
/'H2=0.01 to 01 to form a hard amorphous carbon film. Pressure during test is 041~20T
orr, and the substrate temperature was set to almost the lowest temperature.

As a result, the thickness of the obtained films was controlled by the reaction time, and the thickness of each film ranged from 100 to 100 io.

It exhibited a uniform interference color. The surface unevenness was less than ±10 A, which is the measurement limit of Talystep.

This carbon film is amorphous, and the hydrogen content in the film is 20~
It was 30 atomic percent. The hardness of this film was approximately 8,000 to 10,000 Kl/#2 in terms of Vickers hardness.

The wear resistance of the print was evaluated by the contact friction test method between a magnetic head and a magnetic disk described below. That is, the magnetic head is made of aluminum and titanium carbide and has a Vickers hardness of 4000 K37. , z is used, and a load of approximately 609 mm is applied to the surface of the magnetic disk. /Cm2 onto the protective film, then rotate the magnetic disk at high speed until the magnetic head floats, stop the rotation after floating, and repeat the process of bringing the head into contact with the disk surface again. A stop (C3S) test was conducted. The end,
It was confirmed that even when silicide was used, no wear occurred even after 100,000 cycles.

In this example, one type of metal silicide was used, or two or more types of metal silicides may be used in combination.

Further, the type of magnetic recording medium is not limited to this embodiment, and various types can be used.

Example 2 A magnetic disk substrate with a diameter of 5.25 inches and a thickness of 2
# aluminum alloy was used, and a cobalt-chromium-tantalum compound was deposited thereon to a thickness of about 20 txt by a sputtering method as a recording medium.

To form a protective film, first, for molybdenum oxide, tungsten oxide, tantalum oxide, titanium oxide, cobalt oxide, zirconium oxide, vanadium oxide, and niobium oxide, a normal RF magnetron battering device is used, and the degree of vacuum is 10-3 to 10-3. Using argon sputtering in the range of 10-2 TOrr, the oxide sintered body was used as a target, and the RF power was 100 to 150 W to form a film at a very low temperature. The thickness of the oxide film was controlled by varying the sputtering time in the range of 100-1000 sputtering.

Next, a hard amorphous carbon film was formed in the same manner as in Example 1. The obtained carbon film had properties similar to those of Example 1.

The abrasion resistance of the odor was evaluated by the contact friction test method between a magnetic head and a magnetic disk described below. In other words, the magnetic head is made of aluminum and titanium carbide and has a Gockers hardness of 4000 K! Using a sintered body of J/mtrt2, press the surface of the magnetic disk onto the protective film with a load of 60 g/cm2, then rotate the magnetic disk at high speed until the magnetic head levitates, and then rotate after levitation. A so-called contact start/stop <CSS> test was conducted in which the disk was stopped and the head was brought into contact with the disk surface again. As a result, it was confirmed that no wear occurred even after 100,000 cycles, no matter which oxide was used.

Note that in this example, one type of each metal oxide was used, but two or more types of metal oxides may be used in combination. Further, the type of magnetic recording medium is not limited to this embodiment, and various types can be used.

Example 3 The magnetic disk substrate has a diameter of 5.25 inches and a thickness of 2
An aluminum alloy of M was used, on which a cobalt-chromium-tantalum compound was deposited to a thickness of about 20 mm by sputtering as a recording medium.

To form the protective film, first, for molybdenum nitride, tungsten nitride, tantalum nitride, titanium nitride, cobalt nitride, zirconium nitride, vanadium nitride, and niobium nitride, use an ordinary RF magnetron sputtering device and reduce the vacuum to 10-3. Using argon sputtering in the range of ~10-2 Torr, the nitride sintered body was used as a target, R[power was set to 100 to 150 W, and the film was formed in a very wet state. The thickness of the nitride film was controlled by varying the sputtering time in the range of 100-1000.

Next, a hard amorphous carbon film was formed in the same manner as in Example]. Obtained/: The carbon film had properties similar to those of Example 1.

The wear resistance of pus was evaluated by the contact friction test method between a magnetic head and a magnetic disk described below. That is, a sintered body made of aluminum and titanium carbide with a Vickers hardness of 4000 KCj, 7 mm2 is used as a magnetic head, and is pressed onto the protective film with a load of 60 g/cm2 on the surface of the magnetic disk, and then the magnetic disk is placed between the magnetic head and the magnetic head. A so-called contact start-stop (C3S) test was conducted in which the disk was rotated at high speed until it levitated, then the rotation was stopped, and the head was brought into contact with the disk surface again. As a result, it was confirmed that even when the nitride was used, no wear occurred even after 10,000 TO cycles.

Incidentally, although one type of metal nitride was used in this embodiment, two or more types of metal nitrides may be used in combination. Further, the type of magnetic recording medium is not limited to this embodiment, and various types can be used.

[Effect of the invention 1 As explained above, the magnetic disk according to the present invention has extremely high hardness and excellent wear resistance, and is equipped with a protective film having a thickness of 500 mm or less required for high-density magnetic recording technology. It is highly practical.

[Brief explanation of the drawing]

FIG. 1 is a plan view and a cross-sectional view of a magnetic disk according to the present invention,
FIG. 2 is a schematic diagram of an example of an apparatus used for forming a hard amorphous carbon film. 11... Magnetic disks 12, 25... Substrate 13... Between magnetic recording media 14... Silicide, oxide or nitride film 15...
Hard amorphous carbon film? 1...Vacuum tank? ? ---Counter electrode 23 ---DC power supply? 4...Scrap inlet? 6-...Exhaust pump 27...Valve 28...Methane cylinder 29...Hydrogen cylinder

Claims (6)

[Claims] (1) A magnetic disk having a hard amorphous carbon film on its surface, characterized in that a metal silicide film is formed on the lower surface of the hard amorphous carbon film. (2) The magnetic disk according to claim 1, wherein the metal silicide is at least one selected from molybdenum silicide, tungsten silicide, titanium silicide, cobalt silicide, zirconium silicide, vanadium nitride, niobium silicide, and tantalum silicide. (3) A magnetic disk having a hard amorphous carbon film on its surface, characterized in that a metal oxide film is formed on the lower surface of the hard amorphous carbon film. (4) The magnetic disk according to claim 3, wherein the metal oxide is at least one selected from molybdenum oxide, tungsten oxide, titanium oxide, cobalt oxide, zirconium oxide, vanadium oxide, niobium oxide, and tantalum oxide. (5) A magnetic disk having a hard amorphous carbon film on its surface, characterized in that a metal nitride film is formed on the lower surface of the hard amorphous carbon film. (6) The magnetic disk according to claim 5, wherein the metal nitride is at least one selected from molybdenum nitride, tungsten nitride, titanium nitride, cobalt nitride, zirconium nitride, vanadium nitride, niobium nitride, and tantalum nitride.