JPH01203211A - Hard amorphous carbon film - Google Patents

Abstract

PURPOSE:To obtain a high-hardness amorphous carbon film having excellent adhesive property and lubricity and capable of being appropriately used for a surface protecting layer when deposited on a magnetic disk, etc., by incorporating Si and F into an amorphous carbon film contg. hydrogen. CONSTITUTION:A substrate 3 is set on the substrate holder 2 provided in a vacuum reaction vessel 5, and a DC voltage is impressed between the holder 2 and an electrode 1 set on the side surface. The inside of the vessel 5 is evacuated 4 to about 0.1-50Torr. The raw gas 8-11 obtained by mixing a gaseous hydrocarbon diluted with H2, gaseous SiH4 as Si, and gaseous HP and F is introduced 7 into the vessel 5. Under such conditions, a positive voltage is impressed on the electrode 1, and a negative voltage is impressed on the substrate 3 side to generate a flow discharge. In this case, the strongest glow discharge is generated in the immediate proximity of the electrode 1. However, since the substrate 3 is arranged as described above, the plasma gas of a weak electric field is formed on the substrate 3 in the vicinity of the surface in almost uniform thickness, and the desired amorphous carbon film is obtained.

Description

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

(Prior Art) Magnetic disks and magnetic heads are incorporated into magnetic disk drives and are widely used as information storage devices for computer terminals. Magnetic disks are made of ferrite, iron, cobal+ on aluminum metal plates or plastic substrates.
-, nickel or a compound thereof, or a rare earth metal such as neodymium, samarium, cadrinium, terbium, or an alloy thereof, is used as a magnetic recording medium by depositing it in a thin liquid form by coating or sputtering.

There are various types of magnetic heads, but for example, a thin film magnetic head is a high-density magnetic head in which a coil or yoke is formed in the form of a thin film on a sintered substrate made by molding and sintering mixed grains of aluminum powder and titanium carbide into a plate shape. It is being adopted as a recording head. This magnetic head extracts as a signal changes in magnetic flux according to the direction of magnetization written on the recording medium, and is used as close to the magnetic disk surface as possible. Furthermore, magnetic disks frequently rotate and stop. For this reason, the magnetic head and the magnetic disk surface repeatedly come into contact with and rub against each other, and a protective film is required to protect the recording medium from scratches and the like generated on the recording medium of the magnetic disk.

The key points that a protective film should have are that it has excellent abrasion resistance;
Examples include high adhesion to the substrate or base, 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 because it prevents the protective film from peeling off when the magnetic head contacts or rubs.Since the surface properties of magnetic disk media vary depending on the manufacturing method, select the protective film material and manufacturing method that match the surface properties of the medium. It is necessary.

Conventionally, as this protective film, an oxide or carbon film such as silicon dioxide (SiO□) or alumina (A1203) with a thickness of about 800 Å has been used. Sin□ya＾1□03
It is usually made by coating an organic metal compound of silicon or aluminum dissolved in a solvent, applying a coating, drying and then heat treatment, or by sputtering or vapor deposition in a mixed gas such as argon and oxygen.

A carbon film can be produced by a carbon ion beam deposition method made by discharge using a carbon electrode as described in Japanese Patent Application Laid-Open No. 52-90201, etc., or by a carbon ion beam evaporation method made by discharge using a carbon electrode, as described in Japanese Patent Application Laid-Open No. 52-90201, etc.
al of Non Crystalline 5ol
ids) Vol. 35 & 36, page 435.

(Problems to be Solved by the Invention) However, the various protective film materials mentioned above do not have sufficient hardness, adhesion, and lubricity; for example, the Vickers hardness value of the 5i02 protective film is 2000 k[/ The adhesion of Maro, 2, and alumina was about 3000 kg/s2, and the adhesion of carbon films made by sputtering was about 3000 kg/s2, which could not be said to be good. For example, in a test method for examining the occurrence of scratches caused by abrasion, in which a magnetic head is pressed against a film surface with a load of about 10 g, there is a problem in that abrasion scratches occur within a running distance of about 500 km.

The present invention improves the above-mentioned drawbacks by providing high hardness, especially C.

- To provide a protective film material suitable for application as a magnetic disk surface protective film, which can be deposited on a Ni-P based magnetic recording medium, has excellent wear resistance and adhesion to a substrate, and has good lubricity. .

(Means for solving the problem) The gist of the present invention is to provide high hardness, excellent abrasion resistance, and adhesion.
An object of the present invention is to provide a hard amorphous carbon film material, which is a protective film material suitable for surface protection, and is characterized by further containing silicon and fluorine in an amorphous carbon film containing hydrogen.

The hard amorphous carbon film of the present invention is produced by mixing hydrogen (H2) with methane (CH4) gas in the range of 0,i volume % to 5 volume %. It is synthesized by introducing it into a phase synthesizer.

In FIG. 1, a substrate 3 is placed on a substrate support 2 placed in a vacuum reaction tank 5, and a DC voltage can be applied between it and an electrode 1 placed on the side surface by a DC power supply 6. The inside of the vacuum reactor is evacuated using an exhaust device 4 to maintain a vacuum level of about 0.1 to 50 torr.The raw material gas is the one filled in cylinders 8, 9, 10 and 11. The gas is introduced into the vacuum reactor through the gas supply lower.

Glow discharge is generated in the above pressure range by applying a positive potential to the electrode 1 installed on the side surface and a negative potential to the substrate side. The strongest glow discharge occurs at the portion closest to the side electrode 1, but by arranging it as described above, plasma gas with a weak electric field can be created on the substrate to have a substantially uniform thickness near the surface.

The raw material gas is a hydrocarbon gas diluted with hydrogen, and silicon and fluorine (F) may be mixed in gaseous form, for example, in the form of silane (Si) + 4) and hydrogen fluoride (11F).These mixed gases are On the above substrate, excitation decomposition and ionization occur in the weakly ionized plasma gas generated by DC glow discharge, and it is accelerated in the DC electric field and adheres to the substrate surface, forming an amorphous material containing additive elements uniformly. It becomes a carbon film in poor condition.

(Function) Normally, the film obtained by subjecting a mixed gas of hydrocarbon such as methane and hydrogen to direct current glow discharge is amorphous with about 10%
It contains hydrogen. Hydrogen and fluorine enter the dangling bonds of carbon atoms and fill the carbon bonds, thereby stabilizing the amorphous state.

In order to achieve high hardness, high adhesion to the substrate, and high lubricity of such an amorphous film, the present inventors investigated the effects of adding various metal elements to some of the dangling bonds of carbon atoms. We have been conducting intensive research with the intention of closing with metal elements other than hydrogen, and we have developed a method that is particularly effective in improving adhesion and hardness on Co-N1-P-based magnetic recording media, as well as providing good surface flatness. As a possible method, we have invented a method for synthesizing films to which metal elements are added.

The mechanism of improved adhesion, higher hardness, and higher lubricity due to the addition of metal elements is unclear, but it is likely that chemical bonds are formed between the metal and carbon and between the substrate medium element and the protective film interface. It is thought that this is due to It is said that the lubricity of the film is controlled by the van der Waals force acting between the disk surface and the head due to surface adsorption of moisture, but carbon-fluorine compounds exhibit hydrophobic properties, Since it is thought that water is difficult to adsorb, it is thought that high lubricity is achieved by the effect of fluorine atoms present on the film surface.

In addition, by using such a method, the electric field strength near the substrate can be controlled to an appropriate value because plasma is used at a location away from the main discharge area, and damage to the substrate due to ion bombardment or etching of attached films can be avoided. There are no such problems, and a film with extremely good surface flatness that can be used practically as a magnetic disk protective film can be produced, and also has excellent uniformity.

(Example) An apparatus as shown in FIG. 1 was used to synthesize the hard amorphous carbon film of the present invention. For DC glow discharge, a voltage of several hundred volts was applied using the electrode on the side where the substrate was not installed as the positive electrode. The discharge current density was 1 mA/C112. Methane was used as the reaction gas, and the flow rate was controlled by hydrogen gas so that the amount ranged from 1% by volume to 5% by volume. Silicon is hydrogen 1-2
Silane gas diluted to % by volume was used. Fluorine is hydrogen fluoride (HF) diluted with hydrogen gas to 1-5% by volume.
was used.

The pressure was in the range of 1 Torr to 10 Torr, the temperature of the substrate was about room temperature, and the reaction was carried out for about 5 to 30 minutes.

The resulting film had a thickness of 100 to 100 OA and exhibited a uniform interference color, indicating that it was a film with excellent surface flatness. The contents of carbon, hydrogen, silicon, and fluorine were evaluated using an ion microanalyzer, Loveford backscattering method, and proton recoil detection method.

Hydrogen content is 20 at% to 35 at%, silicon is 1
When the film hardness was evaluated for films containing 00 at. Outside this range, the Vickers hardness decreased significantly.

This value was 2 to 3 times more than that of the conventional amorphous carbon film, indicating extremely high hardness and high adhesion to the Co-N1-P base magnetic recording medium.

The air vibration coefficient of the membrane is A1□03-Ti with a diameter of 5 mm.
Evaluation was made by sliding a sphere made of C alloy on the membrane surface, and the result was 0.
．． The value was 1 or less. As a reference, a similar test was conducted on a film that did not contain 3 fluorine, and the result was approximately 0.5 to 1
．． The value was 0, which was greater than the value of 0.2 or less required for magnetic disks.

(Effects of the Invention) As described above, the hard amorphous carbon film of the present invention has extremely high hardness (and is practically useful as a material suitable for protecting the surface of a Co-N1-P magnetic disk medium.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of the apparatus used in the present invention. In Fig. 1, 1 is an electrode, 2 is a substrate support that will become an electrode, 3 is a substrate, 4 is an exhaust device, 5 is a vacuum reaction tank, 6 is a DC power supply, 7 is a mixed gas supply port, and 8 is a methane gas supply port. 9 is a hydrogen gas cylinder, 10 is a silane gas cylinder diluted with hydrogen, and 11 is a hydrogen fluoride cylinder diluted with hydrogen.

Claims (2)

[Claims] (1) A hard amorphous carbon film characterized by further containing silicon and fluorine in the amorphous carbon film containing hydrogen. (2) In the hard amorphous carbon film according to claim 1, the amount of hydrogen contained is 10 atomic % or more and 35 atomic %.
Hereinafter, a hard amorphous carbon film is characterized in that silicon is contained in an amount of 100 atomic ppm or more and 1 atomic % or less and fluorine is contained in an amount of 1 atomic % or more and 10 atomic % or less.