JPH048509B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a material that has high hardness, excellent adhesion, and has both abrasion resistance and lubricity by being attached to the surface of a magnetic disk, magnetic head, etc. The present invention relates to a hard amorphous carbon film suitable for a surface protective layer.

(Prior Art) Magnetic disks and magnetic heads are widely used as magnetic disk devices as information storage devices for computer terminals. Magnetic disks are manufactured by applying or sputtering a magnetic recording medium using ferrite, iron, cobalt, nickel, or their compounds, or rare earth metals such as neodymium, samarium, cadrinium, and terbium, or compounds made of these, onto a substrate such as aluminum metal or plastic. It is used by attaching it in the form of a thin film. There are various types of magnetic heads, but they extract magnetic flux from magnetization written on a recording medium as a signal, and are used as close to the magnetic disk surface as possible. For this reason, the magnetic head and the magnetic disk are susceptible to mutual wear, 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 include excellent abrasion resistance, high adhesion to the substrate, and excellent surface lubricity.

The hardness of the film can be used to evaluate the abrasion resistance, and the higher the hardness, the better the abrasion resistance. Adhesion is important so that the protective film does not peel off when a magnetic head comes into contact with it or when it is rubbed.

Conventionally, oxides such as silicon dioxide (SiO ₂ ) and alumina (Al ₂ O ₃ ) or carbon films with a thickness of about 800 Å have been used for this purpose. SiO ₂ and Al ₂ O ₃ are usually produced by a method in which an organometallic compound of silicon or aluminum is dissolved in a solvent, coated, dried, and then heat treated, sputtered in a mixed gas of argon and oxygen, or vapor-deposited.

Carbon films can be produced using a carbon ion beam deposition method produced by discharging a carbon electrode as described in Japanese Patent Application Laid-Open No. 52-90281, or as described in the Journal of Non-Crystalline Solids published in 1980.
of Crystalline Solids) Vol. 35 & 36, page 435.

(Problems to be Solved by the _Invention ) The various protective film materials mentioned above, however, do not have ^sufficient hardness and adhesion.
3000Kg/mm ² In the case of carbon film, it was about 3000Kg/mm ² .

The present invention is a protective film material that improves the above-mentioned drawbacks and is suitable for use as a magnetic disk surface protective film, which has high hardness, excellent wear resistance, and has excellent adhesion to a substrate mainly composed of NiP, and has good lubricity. Our goal is to provide the following.

(Means for solving the problem) The gist of the present invention is to further add 100 at.ppm to 1 at.% of chromium (Cr) to an amorphous carbon film containing hydrogen as a protective film material suitable for surface protection. An object of the present invention is to provide a hard amorphous carbon film characterized by containing 50 atomic ppm to 500 atomic ppm of phosphorus (P).

The amorphous carbon film of the present invention is produced _by using a parallel plate type three _- pole direct current glow, as shown in Fig. It is synthesized by introducing it into a discharge plasma vapor phase synthesis apparatus. At that time, screen mesh electrode 3
By using chromium (Cr) as
This method utilizes the phenomenon in which the mesh electrode metal element is bombarded with plasma ions and introduced into the amorphous carbon film.

The amount of metal elements introduced is hydrogen 11 and methane 1
It is controlled by the gas pressure of zero, the discharge pressure, and the voltage applied to the screen mesh electrode 3.

A base 5 to which an amorphous carbon film is to be attached is placed on the cathode electrode plate. The pressure during the reaction by direct current glow discharge may be from 0.1 Torr to 10 Torr, and the conditions may be such that the film hardness is high.

Although the screen mesh electrode 3 can be made of chromium metal, it is more practical to make it by coating a stainless steel mesh with chromium by plating or vapor deposition.

To introduce phosphorus (P), add 0.1mg/P into hydrogen gas.
This may be carried out by introducing a gas 12 mixed with phosphine (PH ₃ ) at a ratio of m ³ or less together with the raw material gas.

(Function) The film obtained by direct current glow discharge of a normal mixed gas of methane and hydrogen is amorphous and about 10
% or more of hydrogen. Hydrogen is said to stabilize the amorphous state by entering the Dangling Vold part of the carbon atom and closing the carbon chain.

The present inventors aimed to close some of the dangling bonds of carbon atoms with metal elements other than hydrogen, regarding the effects of adding various metal elements in order to achieve high hardness of such an amorphous film. conducted extensive research and discovered that chromium (Cr) and phosphorus (P) are effective in improving adhesion and increasing hardness. Although there are some unknown points about the mechanism of improvement in adhesion and increase in hardness due to the addition of metal elements, it is thought that the hardness and adhesion of the film are improved by forming bonds between the metal and carbon. The hydrogen content is approximately 20
It is thought that hardness decreases when the content exceeds ~30 atomic %.

(Example) An apparatus as shown in FIG. 1 was used to synthesize a hard amorphous carbon film. For DC glow discharge, a positive or negative DC voltage of several hundred volts was applied to the electrode on the side where the base 5 was not installed, and DC glow plasma was generated between it and the grounded screen mesh 3. The discharge current density was 1 mA/cm ³ . A voltage from +100 volts to -100 volts was applied to the electrode 6 on which the base body 5 was installed. The reaction gas is methane 10 at 1%~
Using hydrogen gas 11 mixed at 5%, the pressure was 1 torr, the temperature of the substrate was about room temperature, and the reaction was carried out for 1 hour. The screen mesh 3 is suitably 20 to 300 meshes, and in this example, 80 meshes were used.
Phosphorus was introduced into the plasma as PH ₃ .

The resulting film had a thickness of approximately 1 μm and exhibited a uniform interference color. Chromium and phosphorus in the film were analyzed by fluorescent X-ray analysis. When the film hardness was evaluated for films with a chromium content of 100 atomic ppm to 1 atomic ppm and a phosphorus content of 50 to 500 atomic ppm, a Vickers hardness of 8000 to 11000 Kg/mm ² was obtained. This value was 2 to 3 times higher than that of conventional amorphous carbon films, indicating extremely high hardness and high adhesion. In addition, in Figure 1, the vacuum chamber, 2 is the electrode, 4 is the gas inlet, and 7 is the vacuum chamber.
is a heater, 8 is a pressure regulator, and 9 is a rotary pump.

(Effects of the Invention) As described above, the hard amorphous carbon film of the present invention has extremely high hardness and is useful as a new protective film suitable for protecting the surface of a magnetic disk. Furthermore, since the adhesion to the substrate can be controlled by the metal element contained, it can be applied to various substrates and is extremely practical.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of the apparatus used in the present invention. In Fig. 1, 1 is a vacuum chamber, 2 is an electrode, 3 is a screen mesh, 4 is a gas inlet, 5 is a substrate,
6 is an electrode, 7 is a heater, 8 is a pressure regulator, 9 is a rotary pump, 10 is CH ₄ gas, 11 is hydrogen gas, and 12 is PH ₃ /H ₂ mixed gas.

Claims (1)

[Claims] 1 Further add 100 at.ppm to 1 at.% of chromium (Cr) and phosphorus (P) to the amorphous carbon film containing hydrogen.
A hard amorphous carbon film containing 50 atomic ppm to 500 atomic ppm.